WO2019124997A1 - High-strength hot-dip galvanized steel sheet having excellent coating property and method for manufacturing same - Google Patents
High-strength hot-dip galvanized steel sheet having excellent coating property and method for manufacturing same Download PDFInfo
- Publication number
- WO2019124997A1 WO2019124997A1 PCT/KR2018/016300 KR2018016300W WO2019124997A1 WO 2019124997 A1 WO2019124997 A1 WO 2019124997A1 KR 2018016300 W KR2018016300 W KR 2018016300W WO 2019124997 A1 WO2019124997 A1 WO 2019124997A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- steel sheet
- hot
- dip galvanized
- galvanized steel
- oxide
- Prior art date
Links
- 229910001335 Galvanized steel Inorganic materials 0.000 title claims abstract description 46
- 239000008397 galvanized steel Substances 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 25
- 239000011248 coating agent Substances 0.000 title claims abstract description 11
- 238000000576 coating method Methods 0.000 title claims abstract description 11
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 164
- 239000010959 steel Substances 0.000 claims abstract description 164
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 45
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 41
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 40
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 135
- 238000007747 plating Methods 0.000 claims description 85
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 55
- 238000000137 annealing Methods 0.000 claims description 47
- 238000001816 cooling Methods 0.000 claims description 21
- 229910052742 iron Inorganic materials 0.000 claims description 17
- 238000005246 galvanizing Methods 0.000 claims description 14
- 239000002131 composite material Substances 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 12
- 238000005097 cold rolling Methods 0.000 claims description 10
- 230000008569 process Effects 0.000 claims description 10
- 239000012298 atmosphere Substances 0.000 claims description 8
- 238000005098 hot rolling Methods 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 8
- 238000003303 reheating Methods 0.000 claims description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 239000010731 rolling oil Substances 0.000 claims description 3
- 238000004804 winding Methods 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 2
- 229920005989 resin Polymers 0.000 claims description 2
- 238000005507 spraying Methods 0.000 claims description 2
- 235000013980 iron oxide Nutrition 0.000 description 54
- 239000011572 manganese Substances 0.000 description 41
- 239000010410 layer Substances 0.000 description 40
- 239000011701 zinc Substances 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 12
- 229910052725 zinc Inorganic materials 0.000 description 12
- 229910001566 austenite Inorganic materials 0.000 description 11
- 230000002829 reductive effect Effects 0.000 description 11
- 230000000694 effects Effects 0.000 description 9
- 239000011651 chromium Substances 0.000 description 8
- 239000010955 niobium Substances 0.000 description 7
- 238000007254 oxidation reaction Methods 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000002344 surface layer Substances 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000005275 alloying Methods 0.000 description 5
- 239000001257 hydrogen Substances 0.000 description 5
- 230000002452 interceptive effect Effects 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000005554 pickling Methods 0.000 description 5
- 230000000717 retained effect Effects 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000010960 cold rolled steel Substances 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 230000006641 stabilisation Effects 0.000 description 4
- 238000011105 stabilization Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910000794 TRIP steel Inorganic materials 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000011946 reduction process Methods 0.000 description 2
- 229910052814 silicon oxide Inorganic materials 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000000443 aerosol Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000010828 elution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
- C22C18/04—Alloys based on zinc with aluminium as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
- C23C2/0222—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating in a reactive atmosphere, e.g. oxidising or reducing atmosphere
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
- C23C2/0224—Two or more thermal pretreatments
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
- C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
- C23C2/29—Cooling or quenching
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
Definitions
- the present invention relates to a high-strength hot-dip galvanized steel sheet excellent in plating ability and a method of manufacturing the same.
- hot-dip galvanized steel is used to extend the life of automobiles, thereby improving corrosion resistance.
- the surface of the steel sheet is plated with a certain amount of metal such as zinc, zinc having a higher oxidation tendency than iron is firstly corroded in the corrosive environment to protect the iron, which is called a sacrificial method.
- the galvanizing is determined by the quality of the surface of the annealed steel sheet immediately before plating, and the quality of the surface is determined by annealing with elements having high oxidation tendency such as Mn, Si, and Al added to secure the physical properties of the high- The plating ability is deteriorated.
- Korean Patent Publication No. 2010-0030627 discloses a method of oxidizing a steel sheet in a direct flame furnace in an oxidizing atmosphere by controlling the air-fuel ratio of air and fuel to 0.80 to 0.95 in an annealing process, , Mn or Al alone or a composite oxide is formed on the surface of the steel sheet, and then the iron oxide is reduced and annealed in a reducing atmosphere, followed by hot-dip galvanizing to provide a hot-dip galvanized or alloyed hot-dip galvanized steel sheet.
- the components having high affinity with oxygen such as Si, Mn, and Al at a predetermined depth from the surface layer of the steel sheet are internally oxidized to inhibit diffusion to the surface layer.
- the single or complex oxides can be reduced, and the wettability with zinc can be improved, which can reduce the plating. That is, when heated under a high oxygen partial pressure that can oxidize iron, the iron is oxidized up to a certain depth of the surface layer to form an iron oxide layer. Elements that are easier to oxidize than iron are no longer diffusing to the surface because they are oxidized and present as oxides under the iron oxide layer.
- the iron oxide is easily reduced to iron in an atmosphere containing a certain amount of hydrogen and is present as a reduced iron layer in the surface layer, and an element or an oxide thereof which interferes with plating is present under the iron layer and is in contact with zinc Since it is not good, it has good wettability with zinc, and the plating ability is improved.
- Si-doped steel Si is concentrated under the iron oxide immediately during the reduction process to form strip-shaped Si oxides, and peeling at the surface layer including the plating layer, namely, at the interface between the reduced iron and the underlying iron There is a problem that it is difficult to secure the adhesion of the plating layer.
- Korean Patent Laid-Open Publication No. 2009-0006881 A discloses a method for manufacturing a steel ingot by oxidizing an alloy component such as Mn, Si, Al, etc. which is easily oxidized by maintaining a high dew point in the annealing furnace, A method is disclosed in which the oxides externally oxidized on the surface of the steel sheet after annealing are reduced to improve the plating ability.
- This method can solve the plating problem due to the external oxidation of Si, which is easily oxidized by internal oxidation, but the effect is insufficient when a large amount of Mn which is relatively difficult to oxidize is added.
- a high-strength hot-dip galvanized steel sheet in which no plating phenomenon occurs and a problem that the surface oxide is excessively concentrated and the plating layer peels off, and a method of manufacturing the same.
- a high strength hot-dip galvanized steel sheet comprises a base steel sheet; A hot dip galvanized layer formed on the base steel sheet; And oxides of at least one element selected from Si, Mn and Al formed on the surface of the base steel sheet and / or the surface of the base steel sheet in an island shape at a depth of 5 mu m or less.
- a method of manufacturing a high strength hot-dip galvanized steel sheet comprising: preparing a steel sheet; Applying iron oxide to the prepared ground steel sheet; Annealing the iron oxide coated steel sheet; And hot dip galvanizing the annealed ground steel sheet.
- the oxide of the elements which interfere with the plating is dispersed and distributed on the surface of the base steel sheet, the problem that the base steel sheet and the hot-dip galvanized layer are not in contact with each other over a large area can be prevented, A hot-dip galvanized steel sheet excellent in adhesion of plating can be provided.
- FIG. 1 is a conceptual diagram comparing the principle (a) in which peeling occurs in a conventional hot-dip galvanized steel sheet and the principle (b) of preventing the peeling of a hot-dip galvanized steel sheet in the present invention.
- FIG. 2 is a process flow chart comparing the principle (a) in which peeling occurs in a conventional hot-dip galvanized steel sheet and the principle (b) of preventing the peeling of a hot-dip galvanized steel sheet in the present invention.
- the content of each element in the present invention is based on weight unless otherwise specified. Also, the content of gas is based on volume unless otherwise specified.
- the size or diameter of the oxide or the like adhered to the steel sheet means that the wide surface of the steel sheet is observed when the steel sheet is viewed from above, unless otherwise specified or otherwise.
- the hot-dip galvanized steel sheet is not excluded from the scope of the hot-dip galvanized steel sheet of the present invention if it is formed of a zinc-based hot-dip galvanized sheet.
- the hot-dip galvanized steel sheet of the present invention may also include a galvannealed (GA) steel sheet.
- GA galvannealed galvanized
- the inventors of the present invention have found out that the oxide layer of Si, Mn or Al (hereinafter simply referred to as "plating interfering element") is widely formed in the film form at the interface between the base steel sheet and the plated layer, And that the bonding of the plated layer is not smooth.
- the plating layer is not fixed to the base steel sheet, and the plating layer is peeled off in a plate shape. Therefore, in the present invention, the oxide of the plating obstructing element is prevented from being formed in a large area, thereby improving the adhesion between the plating layer and the base steel sheet. That is, when the oxide of the interfering elements is formed on the island, even though the adhesion of the plating layer is poor at the position where the oxide on the island is present, the area is not wide and the adhesion strength of the surrounding plating layer is greatly affected The plating layer can be stably fixed to the steel sheet.
- an oxide of interfering elements such as Si, Mn or Al is formed on the island between the base steel sheet and the plating layer.
- the term " island phase " means that the circle-equivalent diameter is 5 mu m or less. The smaller the size of the island-shaped oxide is, the better the adhesion between the steel sheet and the plating layer is improved. Therefore, the lower limit of the size is not particularly limited. However, in one embodiment of the present invention, the lower limit of the size of the island- .
- the formation of an island-shaped oxide between the base steel sheet and the plating layer is considered to include the concept that some of the oxides penetrate even below the surface of the base steel sheet.
- the oxide may be present within a depth of 5 ⁇ m or less from the surface of the base steel sheet.
- the oxide may be present on the surface of the steel sheet as described above.
- the oxides are formed in an island phase, if the intervals are too narrow, they will have a behavior substantially similar to that of one large area oxide, so that the average interval of the island-shaped oxides may be 0.1 ⁇ or more. However, if the average distance between the oxides is increased, the oxides may be integrated in one place to form a large area oxide. Therefore, according to one embodiment of the present invention, the average distance of the oxides can be set to 5 ⁇ or less.
- the mean spacing of the oxides may mean averaging the distance from the nearest oxide to each oxide (hereinafter the same meaning is used).
- the oxides on the island may be an oxide of one element selected from Si, Mn and Al, a complex oxide of two or more of these elements, or a cluster of oxides of the respective elements.
- the term 'complex oxide' means that two or more elements react with oxygen to form one oxide, and the oxide complex means that each individual oxide is simply aggregated.
- Composites also include complexes of complex oxides.
- iron oxide or iron (Fe) particles or a complex thereof may exist between the oxide on the island and the plating layer.
- the iron oxide serves as a site for forming the plating obstruction elements so as to form an island phase.
- iron particles formed by reducing iron oxide or iron oxide or a complex of iron oxide and iron particles are formed do.
- the iron particles do not necessarily need to be reduced from the iron oxide, and may be included in the form of iron particles from the beginning.
- the iron oxide, the iron particles, or the complex thereof may have a size of about 50 nm to 5 ⁇ .
- the size means the circle equivalent diameter.
- the base steel sheet of the present invention is not limited as long as it is a high strength base steel sheet containing a large amount of Si, Mn and Al.
- the high strength in the present invention does not necessarily have to have high strength at the time of hot dip galvanizing, and it is enough to have a high strength by the subsequent heat treatment or the like.
- the base steel sheet of the present invention may contain Si, Mn and Al as a total of at least 3.5% by weight, and in one embodiment Si: not less than 0.5%, Mn: not less than 2.0%, Sol. And Al: 1.0% or more.
- Si not less than 0.5%
- Mn not less than 2.0%
- Al 1.0% or more.
- the base steel sheet of the present invention comprises 0.05 to 0.3% of C, 0.1 to 2.0% of Si, Al: 0.005 to 1.5%, Mn: 1.5 to 8.0%, P: not more than 0.04% (excluding 0%), S: not more than 0.015% (excluding 0%), N: not more than 0.02% Cr: not more than 1.5% (including 0%), Mo: not more than 0.2% (including 0%), Ti: not more than 0.1% (including 0%), Sb: not more than 0.05% 0%), and B: 0.005% or less (including 0%).
- the composition of the steel sheet is not limited thereto.
- Carbon (C) is an important element added for the stabilization of the retained austenite.
- it is preferably added in an amount of 0.05% or more.
- the C content may be controlled to 0.05% or more. However, if the content exceeds 0.3%, there is a problem that the weldability is poor, which is not preferable.
- Si contributes to stabilization of retained austenite as an element which suppresses precipitation of carbide in ferrite and promotes diffusion of carbon in ferrite into austenite.
- Si can be added in an amount of 0.1% or more, but when the rolling property is considered, the upper limit of the content can be limited to 2.0%. Further, when the Si content is limited to 2.0% or less, the Si oxide can be prevented from being formed on the steel surface.
- Aluminum (Al) is an element contributing to stabilization of retained austenite through inhibition of formation of carbide in ferrite, and may be added in an amount of 0.005% or more. However, if the content exceeds 1.5%, it is difficult to produce a sound slab through reaction with the mold flux during casting, and the surface oxidation can be formed to inhibit the molten conversion, so that the Al content is limited to 1.5% or less .
- Manganese (Mn) is an indispensable element in the metamorphic steel for the formation and stabilization of retained austenite and for suppressing ferrite transformation during cooling.
- Mn may be contained in an amount of 1.5% or more.
- the Mn content may be limited to 8.0% or less because there is a problem that the band formation due to segregation caused by the slab and hot rolling process is excessive and hinders the physical properties.
- S is an impurity element in the steel, and is an element that hinders ductility and weldability of a steel sheet.
- the content exceeds 0.015%, the possibility of hindering the ductility and weldability of the steel sheet increases, so that the upper limit is limited to 0.015%.
- Nitrogen (N) is a component effective to stabilize austenite.
- the content exceeds 0.02%, there is a great risk of occurrence of brittleness and excessively precipitates AlN by bonding with Al, As shown in Fig.
- the content of chromium (Cr) is preferably 1.5% or less (including 0%).
- Cr is an element for increasing the hardenability and serves as an element for suppressing the formation of ferrite, and thus helps to secure 5 to 20% retained austenite, so that a small amount of Cr can be added as needed. However, if it exceeds 1.5%, the amount of iron alloy input will be excessive, which may cause cost increase. In one embodiment of the present invention, the Cr may be limited to 0.7% or less.
- Molybdenum (Mo) is an element to be selectively added, and its content can be set to 0.2% or less (including 0%). Mo has a large effect of contributing to the improvement of strength and is effective in securing strength since it does not deteriorate the wettability of molten metal such as zinc. Even if it exceeds 0.2%, there is no problem, but it is not economically preferable since the effect increase is not so large any more. In one embodiment of the present invention, the Mo may be limited to 0.1% or less.
- Ti titanium
- the content of titanium (Ti) is preferably 0.1% or less (including 0%).
- Ti is a nitride-forming element and has an effect of reducing the concentration of N in the steel, so that a small amount of Ti can be added as needed. If it exceeds 0.1%, the carbon concentration and the strength of the martensite are reduced due to the precipitation of additional carbide in addition to the removal of the solid solution N. Therefore, the upper limit can be limited to 0.1%.
- the antimony (Sb) is a component selectively added to improve the surface quality of the plating, and the content of Sb is preferably 0.05% or less (including 0).
- Sb is added, Sb is concentrated in the surface layer of the steel sheet, and the surface diffusion of Si, Mn, Al and the like is relatively suppressed, thereby improving the plating performance as a whole.
- it exceeds 0.05% the effect of inhibiting surface diffusion of Si, Mn and Al during annealing is deteriorated, so that it is preferable to be limited to 0.05%.
- Nb 0.1% or less (including 0%)
- Niobium (Nb) is optionally added, and the content of Nb is preferably 0.1% or less. Nb is segregated in the form of carbide in the austenite grain boundaries to suppress the coarsening of the austenite grains during the annealing heat treatment to increase the strength. When the Nb content exceeds 0.1%, the amount of alloy iron is increased due to excessive alloying amount.
- the content of boron (B) is preferably 0.005% or less.
- Steel B can be added selectively to ensure strength. However, when the content of B exceeds 0.005%, the steel is concentrated on the annealed surface and the plating ability is greatly reduced.
- the remainder of the present invention is iron (Fe).
- impurities which are not intended from the raw material or the surrounding environment may be inevitably incorporated, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they are known to any person skilled in the art of steel making.
- the manufacturing method of the high strength hot dip galvanized steel sheet of the present invention is not necessarily limited to the following manufacturing method.
- the base steel sheet 1 when the base steel sheet 1 is simply annealed, the film-like oxide 2 is formed on the surface, so that even if plating is performed on the surface, the plating is not performed or the plating layer is not adhered, Unlike the conventional technique (a) in which the gap 5 is generated and the plating layer 3 is peeled off, in order to manufacture the hot-dip galvanized steel sheet having the above-described excellent plating property in the present invention (b) When iron oxide (2) is applied to the surface and annealing is performed, plating inhibiting elements such as Si, Mn or Al existing in the high-strength steel sheet form oxide (4) on the island near the iron oxide while reducing the iron oxide. . When such a steel sheet is plated, it is possible to prevent the problem that the unplated or the plating layer 3 is peeled off.
- the plating interfering elements diffuse to the surface of the steel sheet to form a wide oxide film, thereby greatly reducing the plating adhesion.
- the oxide is formed on the island because it diffuses near the dispersed iron oxide to form an oxide.
- the manufacturing method of the present invention includes the steps of preparing a base steel sheet; Applying iron oxide to the prepared ground steel sheet; Annealing the iron oxide coated steel sheet; And hot dip galvanizing the annealed ground steel sheet.
- the iron oxide used in one embodiment of the present invention may be one or a mixture of two or more selected from FeO, Fe 3 O 4 and Fe 2 O 3 . According to one embodiment of the present invention, these iron oxides can be used in combination with a rolling oil or a resin, in which case uniform coating and coating may be possible. In one embodiment of the present invention, the size (spherical equivalent diameter) of the iron oxide may be between 50 nm and 5 mu m.
- the size of the iron oxide may be set to 5 ⁇ or less in order to prevent the iron oxide from falling off the steel sheet during annealing to cause a defect in the shape of a steel sheet.
- the average interval of the iron oxide may be set to 0.5 to 5 ⁇ ⁇ .
- the reasons for determining the interval of the iron oxide are as described above.
- the annealing atmosphere it is necessary to control the atmosphere and the temperature at the time of annealing so as to prevent oxidation of Fe in the base steel sheet and to cause oxidation reaction of elements such as Si, Mn, and Al.
- the dew point temperature can be maintained at 10 ° C or less during annealing. Also, considering the ability to maintain the atmosphere in a realistic production line, in one embodiment of the present invention, the dew point temperature during annealing may be set at -60 ⁇ or higher.
- the hydrogen content in the atmospheric gas at the time of annealing can be set to 3% or more by volume. Even if the hydrogen content is increased, there is no particular technical problem. However, in one embodiment of the present invention, the hydrogen content can be set to 70% or less in consideration of economical efficiency.
- the temperature of the steel sheet at the time of annealing may be 600 ° C or higher. However, considering the lifetime of the annealing furnace, the steel sheet temperature may be set at 950 ° C or lower. In one embodiment of the present invention, the steel sheet can be recrystallized within the annealing temperature range.
- the time after reaching the target temperature for annealing may be set to 5 seconds or more.
- the annealing time may be limited to 120 seconds or less in one embodiment of the present invention since the annealing time may be somewhat long, but it may cause a rise in cost. In the case of doubling up to recrystallization annealing, the annealing time may also be helpful in obtaining a uniform recrystallized structure.
- a cooling step may follow.
- cooling can be carried out at an average cooling rate of 5 to 100 DEG C / sec. .
- the cooling may be performed in a primary cooling mode and a secondary cooling mode, and the secondary cooling rate may be greater than the primary cooling rate.
- the primary cooling may be performed to 600 to 700 ⁇ ⁇ , after which secondary cooling may be performed.
- the method may further include a step of cold-rolling the steel sheet before the annealing step. That is, when the steel sheet coated with iron oxide on its surface is cold-rolled, the iron oxide can be inserted right under the surface of the cold-rolled steel sheet, and an element such as Si, Mn or Al forms an oxide around the iron oxide Can be more easily achieved.
- iron oxide may be applied using a separate coating equipment to firmly bond to the surface of the steel sheet. That is, in one embodiment of the present invention, iron oxide may be sprayed onto the surface of a steel sheet by using an apparatus capable of spraying and coating iron oxide such as thermal spray or AD (Aerosol Deposition) coating, In this case, the iron oxide can be firmly bonded to the steel sheet surface without cold rolling after coating.
- a separate coating equipment capable of spraying and coating iron oxide such as thermal spray or AD (Aerosol Deposition) coating
- the method may further include the step of pickling the surface of the steel sheet before applying the iron oxide to the surface of the steel sheet, if necessary.
- the pickling can be done in the usual way and does not limit the conditions in particular.
- the step of hot-dip galvanizing the steel sheet may follow.
- the hot dip galvanizing method is not particularly limited, but in one embodiment of the present invention, when zinc is employed as the metal to be plated, it contains 0.13 to 0.3% of Al and the remainder is composed of Zn and unavoidable impurities, The steel sheet is immersed in a galvanizing bath maintained at a predetermined temperature, and then taken out to regulate the amount of deposited metal, followed by cooling to produce a hot-dip galvanized steel sheet.
- the Al content of the plating bath is less than 0.13%, formation of the Fe-Al alloy phase formed at the interface between the base iron and the plating layer is suppressed and plating separation occurs. Therefore, the lower limit is preferably limited to 0.13%.
- the Al content is more than 0.3%, the Al content in the plating layer increases and the weldability is deteriorated.
- the steel sheet when zinc plating is performed, the steel sheet can be reheated to 400 to 550 ° C before plating. That is, in order to form the alloying suppressing layer formed by elution of Fe without delay, the reheating temperature may be 400 ⁇ or higher. However, if the temperature is too high, a phase transformation may occur in some high-strength steels and the desired material can not be satisfied. Therefore, the upper limit of the reheating temperature may be set to 550 ° C.
- the plating bath temperature is limited to 440 to 500 ° C. Below 440 ⁇ , the viscosity of the zinc increases and the rollability of the roll in the plating bath lowers. When the temperature exceeds 500 ⁇ , the evaporation of zinc increases, which is not preferable.
- iron oxide partially or wholly reduced by Si, Mn, Al or the like is present within 5 ⁇ in the depth direction from the surface of the steel sheet and Si, Mn , Al and the like are concentrated and exist in an oxide form.
- the base steel sheet to which the iron oxide is applied may be a hot-rolled steel sheet or a cold-rolled steel sheet.
- the base steel sheet of the present invention can be produced by conventional hot rolling or cold rolling, and the manufacturing conditions are not particularly limited, but the following is a non-limiting example according to one embodiment of the present invention.
- reheating the steel slab satisfying the composition to a temperature between 1100 and 1300 ° C; Finishing the reheated steel slab to a finish temperature of the finishing hot rolling temperature Ar3 or higher;
- the hot-rolled steel sheet may be manufactured by winding the hot-rolled steel sheet at a temperature of 700 ° C or less. If necessary, the cold-rolled steel sheet may be manufactured by pickling the hot-rolled steel sheet followed by cold rolling.
- the slab satisfying the above composition is reheated to a temperature range of 1100 to 1300 ° C. If the reheating temperature is lower than 1100 ° C, there is a problem that the hot rolling load sharply increases. If the reheating temperature is higher than 1300 ° C, the reheating cost increases and the surface scale amount increases.
- the finishing hot rolling temperature of the reheated slab is limited to not less than Ar3 (the temperature at which ferrite starts to appear when the austenite is cooled), which is below the Ar3, and the ferrite + And there is a fear of problems such as defective shape or sheet breakage due to the fluctuation of the hot rolling load due to this.
- the steel sheet After the hot rolling, the steel sheet is wound. At this time, when the coiling temperature exceeds 700 ⁇ ⁇ , the oxide film on the surface of the steel sheet may be excessively generated to cause defects, so that the coiling temperature is limited to 700 ⁇ ⁇ or less.
- the hot-rolled steel sheet can be obtained by the above-mentioned process, and the hot-dip galvanized steel sheet of the present invention can be obtained by applying the iron oxide on the surface of the hot-rolled steel sheet, annealing and plating the surface.
- the hot-dip galvanized steel sheet of the present invention may be obtained by subjecting the hot-rolled steel sheet to pickling and cold rolling to obtain a cold-rolled steel sheet, coating the surface with iron oxide, annealing and plating.
- the pickling and cold rolling conditions are not particularly limited and ordinary methods can be used.
- the steel having the composition shown in Table 1 below was melted to prepare a slab.
- the produced slab was maintained at 1200 ° C for 1 hour, cooled to 600 ° C at 900 ° C, which is the temperature of Ar3 or higher, and then cooled to 100 ° C by keeping it in a warming furnace for 1 hour to simulate the winding process.
- the cold-rolled hot-rolled steel sheet was pickled at 60 ° C in a 17% by volume HCl solution for 30 seconds to remove the scale of the steel sheet.
- the pickled steel sheet was coated with the following Table 2, and the steel sheet coated with the iron oxide was cold-rolled at a reduction ratio of 50%. It was confirmed that the iron oxide was evenly distributed on the surface of the steel sheet by cold rolling. At this time, iron oxide was mixed with rolling oil to distribute the iron oxide more uniformly.
- the steel sheet was subjected to annealing (conducted in a 5% hydrogen + 95% nitrogen atmosphere) and hot-dip galvanizing under the conditions shown in Table 3.
- the remainder excluding Al was Zn.
- the amount of plating adhered was adjusted to 60 g / m 2 on one side, and the steel sheet was reheated before entering the plating bath to adjust the temperature to 470 ° C.
- the steel composition, annealing and plating conditions of Inventive Examples 1 and 2 and Comparative Example 1 were all applied equally, and Fe oxide was classified into the inventive example and the comparative example depending on whether or not Fe oxide was used.
- Inventive Samples 3, 4 and 5 and Comparative Example 2 were also applied in the same manner for steel composition, annealing condition, plating condition, and the like, but using Fe oxide was set differently.
- the iron oxide was inserted and annealed from the surface of the steel sheet, it was confirmed that the iron oxide was reduced to elements such as Si, Mn and Al after the iron oxide was present within a depth of 5 ⁇ m from the surface of the steel sheet. Therefore, there was a region where the iron oxide was reduced to a depth of 5 ⁇ ⁇ from the surface of the steel sheet, and a complex oxide of Si, Mn and Al was present in the vicinity. Some of the oxides of Si, Mn, and Al are also present on the surface of the steel sheet, but there is no problem that the problem of unplated and adhesion of the plating deteriorates even when hot-dip galvanizing is performed because reduced iron or iron oxide exists thereon.
- oxides such as Si, Mn and Al in the form of film are widely present on the surface of the base steel sheet, and it is difficult to secure the adhesion of the plating layer or the surface quality and the adhesion of the plating layer.
- Comparative Example 1 the surface quality of Comparative Example 1 was not ensured.
- Comparative Example 2 the reason why the surface quality and the adhesion of the plating layer were not ensured was that the content of Si was relatively high in Comparative Example 2 and the annealing temperature was about 60 ° C And the amount of Si and Mn diffusing to the surface during annealing was high.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Coating With Molten Metal (AREA)
Abstract
The present invention relates to a high-strength hot-dip galvanized steel sheet having an excellent coating property and a method for manufacturing the same. A high-strength hot-dip galvanized steel sheet according to an aspect of the present invention may comprise: a base steel sheet; a hot-dip galvanized layer formed on the base steel sheet; and an oxide of at least one element selected from Si, Mn, and Al, formed in an island phase between the base steel sheet and the hot-dip galvanized layer.
Description
본 발명은 도금성이 우수한 고강도 용융아연도금강판 및 그 제조방법에 관한 것이다. The present invention relates to a high-strength hot-dip galvanized steel sheet excellent in plating ability and a method of manufacturing the same.
근래에 자동차용 강재에 고강도 강판을 적용함으로써 안전성 향상 및 두께감소에 의한 경량화를 이루어 왔다. 강도향상을 위해서는 석출강화강, 고용강화강 등이 개발되어 왔으며, 또한 강도향상과 동시에 연신율을 향상시키기 위해 변태유기소성강(Transformation Induced Plasticity Steel, TRIP강)이 개발되었다. 이들 고강도강은 일반강 대비 다양한 합금원소를 첨가하게 되는데, 특히 Mn, Si, Al, Cr등의 산화 경향이 높은 원소를 많이 첨가하게 된다. In recent years, high strength steel sheets have been applied to automotive steels to improve safety and reduce weight by thickness reduction. In order to improve strength, precipitation strengthened steel and solid solution strengthened steel have been developed. Transformation Induced Plasticity Steel (TRIP steel) has been developed to improve the strength and elongation at the same time. These high-strength steels add various alloying elements compared to general steels, and particularly high-oxidation elements such as Mn, Si, Al, and Cr are added in large amounts.
일반적으로 자동차의 수명연장을 위해 용융아연도금강판을 사용하여 내식성을 향상시킨다. 특히, 강판의 표면을 일정량의 아연과 같은 금속으로 용융도금을 하게 되면, 부식환경에서 철보다 산화경향이 높은 아연이 먼저 부식되면서 철을 보호하게 되는데 이를 희생방식이라 한다. Generally, the use of hot-dip galvanized steel is used to extend the life of automobiles, thereby improving corrosion resistance. In particular, if the surface of the steel sheet is plated with a certain amount of metal such as zinc, zinc having a higher oxidation tendency than iron is firstly corroded in the corrosive environment to protect the iron, which is called a sacrificial method.
아연도금은 도금이 실시되기 직전의 소둔 강판 표면상태에 따라 도금품질이 결정되게 되는데, 고강도강의 물성을 확보하기 위해 첨가된 Mn, Si, Al 등 산화경향이 높은 원소들에 의한 소둔 중 표면산화물 형성으로 인해 도금성이 악화된다. 즉, 소둔과정에서 소둔로 중에 존재하는 미량의 산소 혹은 수증기와 반응하여 강판 표면에 Si, Mn 또는 Al 단독 혹은 복합산화물을 형성함으로서 아연의 젖음성을 방해하여 도금강판 표면에 국부적 혹은 전체적으로 도금금속이 부착되지 않는 미도금이 발생되게 되며, 또한 이러한 산화물들로 인해 용융도금 과정에서 도금층 밀착성 확보에 필요한 합금화 억제층(Fe2Al5) 형성이 미흡하여 도금층 박리를 발생시키는 등 도금강판의 도금품질이 크게 저하된다.The galvanizing is determined by the quality of the surface of the annealed steel sheet immediately before plating, and the quality of the surface is determined by annealing with elements having high oxidation tendency such as Mn, Si, and Al added to secure the physical properties of the high- The plating ability is deteriorated. That is, by reacting with a trace amount of oxygen or water vapor present in the annealing furnace in the annealing process, Si, Mn, or Al alone or complex oxide is formed on the surface of the steel sheet, thereby hindering the wettability of the zinc and thereby locally or entirely plating metal (Fe 2 Al 5 ) necessary for securing the adhesion of the plating layer in the process of hot dip galvanization is insufficient due to such oxides, and the plating quality is deteriorated due to the plating, .
고강도강의 도금품질 향상을 위해 여러가지 기술이 제안되었다. 그 중 한국 특허공개 2010-0030627호는 소둔과정에서 공기와 연료의 공연비를 0.80~0.95로 제어하여, 산화성 분위기의 직접 화염로(Direct Flame Furnace)내에서 강판을 산화시켜, 강판 내부 일정한 깊이까지 Si, Mn 또는 Al 단독 혹은 복합산화물을 포함한 철 산화물을 형성시킨 다음, 환원성 분위기에서 철 산화물을 환원소둔시킨 후 용융아연도금을 실시하여 도금품질이 우수한 용융아연도금 또는 합금화 용융아연도금 강판을 제공한다.Several techniques have been proposed to improve the plating quality of high strength steels. Korean Patent Publication No. 2010-0030627 discloses a method of oxidizing a steel sheet in a direct flame furnace in an oxidizing atmosphere by controlling the air-fuel ratio of air and fuel to 0.80 to 0.95 in an annealing process, , Mn or Al alone or a composite oxide is formed on the surface of the steel sheet, and then the iron oxide is reduced and annealed in a reducing atmosphere, followed by hot-dip galvanizing to provide a hot-dip galvanized or alloyed hot-dip galvanized steel sheet.
이와 같이 소둔공정에서 산화후 환원 방법을 사용하면, 강판 표층에서부터 일정 깊이에 Si, Mn, Al등 산소와 친화력이 큰 성분들이 내부산화되어 표층으로 확산이 억제되어 상대적으로 표층에는 Si, Mn 또는 Al 단독 혹은 복합산화물이 줄어들게 되어 아연과의 젖음성이 개선되어 미도금을 감소시킬 수 있다. 즉 철이 산화될 수 있는 높은 산소 분압하에서 가열하면 표층부 일정 깊이까지 철이 산화되어 철산화물층을 형성한다. 철보다 산화가 쉬운 원소들은 철 산화층 아래에서 산화되어 산화물로 존재하기 때문에 더이상 표면으로 확산하지 못한다. 이후 이어지는 환원공정에서 철산화물은 일정량의 수소가 포함된 분위기 중에서 쉽게 철로 환원되어 표층에는 환원된 철 층으로 존재하고, 도금을 방해하는 원소 또는 이들의 산화물은 철 층 아래에 존재하여 아연과 접촉하지 못하므로 아연과의 젖음성이 좋아 도금성이 개선된다. 하지만 Si이 첨가된 강종의 경우, 환원공정 중에 Si이 산화철 직하에 농화되어 띠형태의 Si 산화물을 형성하게 되어 도금층을 포함한 표층부에서 박리, 즉 환원된 철과 그 아래의 소지철 사이의 계면에서 박리가 발생하여 도금층 밀착성 확보가 어려운 문제가 있다.In the annealing process, if the oxidation-reduction method is used, the components having high affinity with oxygen such as Si, Mn, and Al at a predetermined depth from the surface layer of the steel sheet are internally oxidized to inhibit diffusion to the surface layer. The single or complex oxides can be reduced, and the wettability with zinc can be improved, which can reduce the plating. That is, when heated under a high oxygen partial pressure that can oxidize iron, the iron is oxidized up to a certain depth of the surface layer to form an iron oxide layer. Elements that are easier to oxidize than iron are no longer diffusing to the surface because they are oxidized and present as oxides under the iron oxide layer. In the subsequent reduction process, the iron oxide is easily reduced to iron in an atmosphere containing a certain amount of hydrogen and is present as a reduced iron layer in the surface layer, and an element or an oxide thereof which interferes with plating is present under the iron layer and is in contact with zinc Since it is not good, it has good wettability with zinc, and the plating ability is improved. However, in the case of Si-doped steel, Si is concentrated under the iron oxide immediately during the reduction process to form strip-shaped Si oxides, and peeling at the surface layer including the plating layer, namely, at the interface between the reduced iron and the underlying iron There is a problem that it is difficult to secure the adhesion of the plating layer.
고강도강의 도금성 향상을 위한 또 다른 방법으로 대한민국 공개특허 2009-0006881 A는 소둔로내의 이슬점(Dew Point)을 높게 유지하여 산화가 용이한 Mn, Si, Al 등의 합금성분을 강 내부에 내부산화시킴으로서 소둔후 강판 표면에 외부산화되는 산화물을 감소시켜 도금성을 향상시키는 방법이 게시되어 있다. 이 방법으로는 내부산화가 용이한 Si의 외부산화에 의한 도금성 문제는 해결이 가능하지만, 내부산화가 상대적으로 어려운 Mn이 다량 첨가되어 있는 경우는 그 효과가 미미하다.As another method for improving the plating performance of high-strength steels, Korean Patent Laid-Open Publication No. 2009-0006881 A discloses a method for manufacturing a steel ingot by oxidizing an alloy component such as Mn, Si, Al, etc. which is easily oxidized by maintaining a high dew point in the annealing furnace, A method is disclosed in which the oxides externally oxidized on the surface of the steel sheet after annealing are reduced to improve the plating ability. This method can solve the plating problem due to the external oxidation of Si, which is easily oxidized by internal oxidation, but the effect is insufficient when a large amount of Mn which is relatively difficult to oxidize is added.
본 발명의 한가지 측면에 따르면, 미도금 현상이 발생하지 않음은 물론이고 표면산화물이 지나치 농화되어 도금층이 박리되는 문제점이 해결되는 고강도 용융아연도금강판 및 그 제조방법이 제공될 수 있다.According to one aspect of the present invention, there can be provided a high-strength hot-dip galvanized steel sheet in which no plating phenomenon occurs and a problem that the surface oxide is excessively concentrated and the plating layer peels off, and a method of manufacturing the same.
본 발명의 과제는 상술한 내용에 한정되지 아니한다. 본 발명이 속하는 기술분야에서 통상의 지식을 가지는 자라면 누구라도 본 발명 명세서의 전반적인 내용을 통하여 본 발명의 추가적인 과제를 이해하는데 아무런 문제점이 없을 것이다.The object of the present invention is not limited to the above description. It will be understood by those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or essential characteristics thereof.
본 발명의 한가지 측면에 따른 고강도 용융아연도금강판은 소지강판; 소지강판 위에 형성된 용융아연도금층; 및 상기 소지강판의 표면 및/또는 소지강판의 표면으로부터 깊이 5㎛ 이내에서 아일랜드 상으로 형성된 Si, Mn 및 Al 중에서 선택된 1종 이상의 원소의 산화물을 포함할 수 있다.A high strength hot-dip galvanized steel sheet according to one aspect of the present invention comprises a base steel sheet; A hot dip galvanized layer formed on the base steel sheet; And oxides of at least one element selected from Si, Mn and Al formed on the surface of the base steel sheet and / or the surface of the base steel sheet in an island shape at a depth of 5 mu m or less.
본 발명의 다른 한가지 측면에 따른 고강도 용융아연도금강판의 제조방법은 소지강판을 준비하는 단계; 상기 준비된 소지강판에 철 산화물을 도포하는 단계; 상기 철산화물이 도포된 소지강판을 소둔하는 단계; 및 상기 소둔된 소지강판을 용융아연도금하는 단계를 포함할 수 있다.According to another aspect of the present invention, there is provided a method of manufacturing a high strength hot-dip galvanized steel sheet, comprising: preparing a steel sheet; Applying iron oxide to the prepared ground steel sheet; Annealing the iron oxide coated steel sheet; And hot dip galvanizing the annealed ground steel sheet.
본 발명에 의할 경우, 소지강판 표면에 도금을 방해하는 원소들의 산화물이 분산 분포 되어 있어서 소지강판과 용융아연도금층이 넓은 면적에 걸쳐서 접촉하지 못하는 문제가 방지될 수 있어 합금화 억제층이 균일하게 형성되어 도금 밀착성이 우수한 용융아연도금강판이 제공될 수 있다.According to the present invention, since the oxide of the elements which interfere with the plating is dispersed and distributed on the surface of the base steel sheet, the problem that the base steel sheet and the hot-dip galvanized layer are not in contact with each other over a large area can be prevented, A hot-dip galvanized steel sheet excellent in adhesion of plating can be provided.
도 1은 종래의 용융아연도금강판에서 박리가 일어나는 원리(a)와 본 발명에서 용융아연도금강판의 박리를 방지하는 원리(b)를 비교한 개념도이다.BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram comparing the principle (a) in which peeling occurs in a conventional hot-dip galvanized steel sheet and the principle (b) of preventing the peeling of a hot-dip galvanized steel sheet in the present invention.
도 2는 종래의 용융아연도금강판에서 박리가 일어나는 원리(a)와 본 발명에서 용융아연도금강판의 박리를 방지하는 원리(b)를 비교한 공정흐름도이다.2 is a process flow chart comparing the principle (a) in which peeling occurs in a conventional hot-dip galvanized steel sheet and the principle (b) of preventing the peeling of a hot-dip galvanized steel sheet in the present invention.
이하, 본 발명을 상세히 설명한다. Hereinafter, the present invention will be described in detail.
본 발명에서 각 원소의 함량은 특별히 달리 표현하지 아니하는 한 중량을 기준으로 한다는 점에 유의할 필요가 있다. 또한, 가스의 함량은 특별히 달리 표현하지 아니하는 한 부피를 기준으로 한다. 또한, 본 발명에서 강판에 부착된 산화물 등의 크기 또는 직경이라 함은 특별히 달리 표현하거나 상식에 어긋나지 아니하는 한 강판의 넓은 면을 위에서 내려 보았을 때 관찰되는 것을 의미한다. It should be noted that the content of each element in the present invention is based on weight unless otherwise specified. Also, the content of gas is based on volume unless otherwise specified. In the present invention, the size or diameter of the oxide or the like adhered to the steel sheet means that the wide surface of the steel sheet is observed when the steel sheet is viewed from above, unless otherwise specified or otherwise.
용융아연도금강판은 아연을 주성분으로 용융도금층이 형성된 강판이라면 본 발명의 용융아연도금강판의 범주에서 제외되지 않으며, 본 발명의 한가지 구현례에서는 상기 용융아연도금강판은 아연을 50중량% 이상 포함(소지강판과 합금화된 경우에는 Fe를 제외한 나머지 성분 중에서 50중량% 이상 포함)하는 용융도금강판일 수 있다. 또한, 본 발명의 용융아연도금강판에는 합금화 용융아연도금(Galva-annealed; GA) 강판도 포함될 수 있다. 합금화 용융아연도금(GA) 강판의 경우에는 본 발명의 특징적인 구성을 이용할 경우 미도금이 발생하는 것을 개선시킬 수 있으며, 합금화 온도를 떨어뜨려 소둔재의 연신율을 확보하는데 유리할 수 있다.The hot-dip galvanized steel sheet is not excluded from the scope of the hot-dip galvanized steel sheet of the present invention if it is formed of a zinc-based hot-dip galvanized sheet. In one embodiment of the present invention, the hot- And 50% by weight or more of the other components except Fe in the case of alloying with the base steel). Further, the hot-dip galvanized steel sheet of the present invention may also include a galvannealed (GA) steel sheet. In the case of a galvannealed galvanized (GA) steel sheet, it is possible to improve the occurrence of unplating when the characteristic constitution of the present invention is used, and it may be advantageous to secure the elongation of the annealed material by lowering the alloying temperature.
본 발명의 발명자들은 도금층 박리는 소지강판과 도금층의 계면에서 Si, Mn 또는 Al(이하, 이들을 간략히 '도금방해원소'라고 부르기도 함)의 산화물이 필름형태로 넓게 형성되어, 넓은 면적에서 소지강판과 도금층의 결합이 원활하지 못하다는 것이 주요한 원인으로 작용한다는 것을 발견하게 되었다.The inventors of the present invention have found out that the oxide layer of Si, Mn or Al (hereinafter simply referred to as "plating interfering element") is widely formed in the film form at the interface between the base steel sheet and the plated layer, And that the bonding of the plated layer is not smooth.
즉, 도금층과 소지강판이 접촉하지 못하는 면적이 넓을 경우에는 도금층이 소지강판에 고정되지 못하여, 판 형태로 도금층이 박리되는 문제가 발생한다. 따라서, 본 발명에서는 도금방해원소의 산화물이 넓은 면적으로 형성되지 못하도록 하여 도금층과 소지강판 사이의 밀착성을 개선하고자 한다. 즉, 도금방해원소들의 산화물이 아일랜드(island) 상으로 형성될 경우에는 비록 아일랜드 상의 산화물이 존재하는 위치에서는 도금층의 밀착성이 열악하여도 그 면적이 넓지 않아 주위의 도금층의 밀착 강도에 큰 영향을 주지 못하기 때문에 도금층이 안정적으로 소지강판에 고정될 수 있다.That is, when the area where the plating layer and the base steel sheet are not in contact with each other is large, the plating layer is not fixed to the base steel sheet, and the plating layer is peeled off in a plate shape. Therefore, in the present invention, the oxide of the plating obstructing element is prevented from being formed in a large area, thereby improving the adhesion between the plating layer and the base steel sheet. That is, when the oxide of the interfering elements is formed on the island, even though the adhesion of the plating layer is poor at the position where the oxide on the island is present, the area is not wide and the adhesion strength of the surrounding plating layer is greatly affected The plating layer can be stably fixed to the steel sheet.
도 1을 통하여 종래의 용융아연도금강판에서 박리가 일어나는 원리(a)와 본 발명에서 용융아연도금강판의 박리를 방지하는 원리(b)에 대하여 상세히 설명한다. 도 1에서 볼 수 있듯이, 종래와 같이 소지강판(1)의 표면에 도금방해원소의 산화물(2)이 넓게 필름상으로 형성될 경우, 박리의 원인이 되는 외력이 작용할 때 도금층과 소지철이 결합되어 있는 면적이 좁기 때문에 도금층이 더이상 지탱하지 못하고 박리되어 버리나(a), 만일 산화물이 아일랜드 상으로 미세하게 분산 분포 된다면 도금층과 소지철이 결합되어 있는 부분의 면적이 넓어져서 도금층이 분리되지 않게 된다(b). The principle (a) of peeling in the conventional hot-dip galvanized steel sheet and the principle (b) of preventing the peeling of the hot-dip galvanized steel sheet in the present invention will be described in detail with reference to FIG. As shown in FIG. 1, when the oxide 2 of the plating obstruction element is formed on the surface of the base steel sheet 1 in a wide film-like manner, the plating layer and the base steel are combined when an external force, (A), if the oxide is finely dispersed in the island phase, the area of the portion where the plating layer and the substrate iron are bonded becomes wider and the plating layer is not separated (see ).
따라서, 본원 발명에서는 소지강판 및 상기 소지강판 위에 형성된 도금층을 포함하는 도금강판에서 소지강판과 도금층 사이에 Si, Mn 또는 Al 등의 도금방해원소들의 산화물을 아일랜드(island) 상으로 형성시킨다. 본 발명에서 아일랜드 상이라 함은 원 상당 직경이 5㎛ 이하인 것을 의미한다. 아일랜드 상 산화물의 크기가 작을수록 소지강판과 도금층의 밀착성은 개선되므로 그 크기의 하한을 특별히 제한할 필요는 없으나, 본 발명의 한가지 구현례에서는 상기 아일랜드 상 산화물의 크기의 하한은 10nm로 정할 수 있다. 본 발명에서 소지강판과 도금층 사이에 아일랜드 상의 산화물이 형성된다는 것은 일부 산화물이 소지강판의 표면 아래에까지 침투하여 형성하는 것까지 포함하는 개념임에 유의할 필요가 있다. 본 발명의 한가지 구현례에 따르면 상기 산화물은 소지강판의 표면으로부터 깊이 5㎛ 이내에까지 존재할 수 있다. 산화물이 소지강판의 표면에 존재할 수 있다는 것은 전술한 바와 같다. Therefore, in the present invention, in the coated steel sheet including the base steel sheet and the plating layer formed on the base steel sheet, an oxide of interfering elements such as Si, Mn or Al is formed on the island between the base steel sheet and the plating layer. In the present invention, the term " island phase " means that the circle-equivalent diameter is 5 mu m or less. The smaller the size of the island-shaped oxide is, the better the adhesion between the steel sheet and the plating layer is improved. Therefore, the lower limit of the size is not particularly limited. However, in one embodiment of the present invention, the lower limit of the size of the island- . In the present invention, the formation of an island-shaped oxide between the base steel sheet and the plating layer is considered to include the concept that some of the oxides penetrate even below the surface of the base steel sheet. According to one embodiment of the present invention, the oxide may be present within a depth of 5 μm or less from the surface of the base steel sheet. The oxide may be present on the surface of the steel sheet as described above.
또한, 산화물들이 아일랜드 상으로 형성된다고 하더라도 그 간격이 너무 좁을 경우에는 실질적으로 하나의 넓은 면적의 산화물과 유사한 거동을 할 것이므로, 아일랜드 상 산화물의 평균 간격은 0.1㎛ 이상일 수 있다. 다만, 산화물의 평균 간격이 커지면 한곳에 산화물이 집적되어 큰 면적의 산화물을 형성시킬 수 있으므로, 본 발명의 한가지 구현례에 따르면 상기 산화물의 평균 간격은 5㎛ 이하로 정할 수 있다. In addition, even if the oxides are formed in an island phase, if the intervals are too narrow, they will have a behavior substantially similar to that of one large area oxide, so that the average interval of the island-shaped oxides may be 0.1 탆 or more. However, if the average distance between the oxides is increased, the oxides may be integrated in one place to form a large area oxide. Therefore, according to one embodiment of the present invention, the average distance of the oxides can be set to 5 탆 or less.
본 발명의 한가지 구현례에서 상기 산화물들의 평균 간격은 산화물 별로 가장 인접한 산화물과의 거리를 평균한 것을 의미할 수 있다(이하, 동일한 의미로 사용함).In one embodiment of the present invention, the mean spacing of the oxides may mean averaging the distance from the nearest oxide to each oxide (hereinafter the same meaning is used).
또한, 본 발명의 한가지 구현례에서 상기 아일랜드 상의 산화물들은 Si, Mn 및 Al 중에서 선택된 하나의 원소의 산화물, 이들 중 둘 이상의 원소들의 복합산화물 또는 각 원소들의 산화물의 복합체(cluster)일 수 있다. 여기서 복합산화물이라 함은 둘 이상의 원소들이 산소와 반응하여 하나의 산화물을 형성하는 것을 의미하며, 산화물 복합체라 함은 각각의 개별 산화물이 단순히 응집하여 존재하는 것을 의미한다. 복합체에는 복합산화물의 복합체도 포함된다.Further, in one embodiment of the present invention, the oxides on the island may be an oxide of one element selected from Si, Mn and Al, a complex oxide of two or more of these elements, or a cluster of oxides of the respective elements. Here, the term 'complex oxide' means that two or more elements react with oxygen to form one oxide, and the oxide complex means that each individual oxide is simply aggregated. Composites also include complexes of complex oxides.
본 발명의 한가지 구현례에 따르면 상기 아일랜드 상의 산화물과 도금층 사이에는 철 산화물 또는 철(Fe) 입자 또는 이들의 복합체가 존재할 수 있다. 철 산화물은 상기 도금방해원소들이 아일랜드 상으로 형성될 수 있도록 형성 사이트(site)를 제공하는 역할을 하며, 그 결과 철 산화물 또는 철 산화물이 환원되어 형성된 철 입자 또는 철 산화물과 철 입자의 복합체가 형성된다. 다만, 상기 철 입자는 반드시 철 산화물로부터 환원된 것일 필요는 없으며, 처음부터 철 입자의 형태로 포함될 수도 있다.According to one embodiment of the present invention, iron oxide or iron (Fe) particles or a complex thereof may exist between the oxide on the island and the plating layer. The iron oxide serves as a site for forming the plating obstruction elements so as to form an island phase. As a result, iron particles formed by reducing iron oxide or iron oxide or a complex of iron oxide and iron particles are formed do. However, the iron particles do not necessarily need to be reduced from the iron oxide, and may be included in the form of iron particles from the beginning.
이러한 역할을 충분히 수행할 수 있도록 하기 위해서 상기 철 산화물, 철 입자 또는 이들의 복합체는 50nm~5㎛ 정도의 크기를 가질 수 있다. 여기서 크기라 함은 원상당 직경을 의미한다. In order to sufficiently perform such a role, the iron oxide, the iron particles, or the complex thereof may have a size of about 50 nm to 5 탆. Here, the size means the circle equivalent diameter.
본 발명의 소지강판은 Si, Mn 및 Al을 다량으로 포함하는 고강도 소지강판이라면 그 종류를 제한하지 않는다. 또한 본 발명에서 고강도라 함은 반드시 용융아연도금시에 높은 강도를 가질 필요는 없으며 이후의 열처리 등에 의하여 높은 강도를 가질 수 있어도 충분하다. The base steel sheet of the present invention is not limited as long as it is a high strength base steel sheet containing a large amount of Si, Mn and Al. The high strength in the present invention does not necessarily have to have high strength at the time of hot dip galvanizing, and it is enough to have a high strength by the subsequent heat treatment or the like.
본 발명의 소지강판은 도금방해원소인 Si, Mn 및 Al을 함량 합계로 3.5중량% 이상 포함할 수 있으며, 한가지 구현례에서는 Si: 0.5% 이상, Mn: 2.0% 이상, Sol. Al: 1.0% 이상 중 1종 이상을 포함할 수 있다. 소지강판이 도금방해원소를 이와 같이 포함할 경우, 본 발명의 구성에 따른 효과를 더욱 유리하게 얻을 수 있다.The base steel sheet of the present invention may contain Si, Mn and Al as a total of at least 3.5% by weight, and in one embodiment Si: not less than 0.5%, Mn: not less than 2.0%, Sol. And Al: 1.0% or more. When the base steel sheet includes the plating interfering element in this way, the effect according to the constitution of the present invention can be obtained more advantageously.
또한, 본 발명의 한가지 구현례에 따르면, 본 발명의 소지강판은 중량%로, C: 0.05~0.3%, Si: 0.1~2.0%, Sol. Al: 0.005~1.5%, Mn: 1.5~8.0%, P: 0.04% 이하(0%는 제외), S: 0.015% 이하(0%는 제외), N: 0.02% 이하(0%는 제외), Cr: 1.5%이하(0%포함), Mo: 0.2% 이하(0% 포함), Ti: 0.1% 이하(0% 포함), Sb: 0.05% 이하(0% 포함), Nb: 0.1% 이하(0% 포함), B: 0.005% 이하(0% 포함) 을 포함하는 조성을 가질 수 있으나, 반드시 소지강판의 조성을 이로 제한하는 것은 아니다.According to one embodiment of the present invention, the base steel sheet of the present invention comprises 0.05 to 0.3% of C, 0.1 to 2.0% of Si, Al: 0.005 to 1.5%, Mn: 1.5 to 8.0%, P: not more than 0.04% (excluding 0%), S: not more than 0.015% (excluding 0%), N: not more than 0.02% Cr: not more than 1.5% (including 0%), Mo: not more than 0.2% (including 0%), Ti: not more than 0.1% (including 0%), Sb: not more than 0.05% 0%), and B: 0.005% or less (including 0%). However, the composition of the steel sheet is not limited thereto.
이하, 본 발명의 일 구현례에서 소지강판의 조성을 정한 이유에 대하여 간략히 설명한다.Hereinafter, the reason why the composition of the ground steel sheet is determined in one embodiment of the present invention will be briefly described.
C: 0.05~0.3%C: 0.05 to 0.3%
탄소(C)는 잔류 오스테나이트 안정화를 위해서 첨가되는 중요한 원소로써, 이를 위해서는 0.05% 이상으로 첨가됨이 바람직하다. 본 발명의 한가지 구현례에 따르면 상기 C 함량은 0.05% 이상으로 제어될 수도 있다. 하지만, 그 함량이 0.3%를 초과하면 용접성이 열위하는 문제가 있으므로 바람직하지 못하다.Carbon (C) is an important element added for the stabilization of the retained austenite. For this purpose, it is preferably added in an amount of 0.05% or more. According to one embodiment of the present invention, the C content may be controlled to 0.05% or more. However, if the content exceeds 0.3%, there is a problem that the weldability is poor, which is not preferable.
Si: 0.1~2.0%Si: 0.1 to 2.0%
실리콘(Si)은 페라이트 내에서 탄화물의 석출을 억제하고, 페라이트 내 탄소가 오스테나이트로 확산하는 것을 조장하는 원소로써 잔류 오스테나이트의 안정화에 기여한다. 이를 위해서는 Si를 0.1% 이상으로 첨가할 수 있으나, 압연성을 고려할 경우 그 함량의 상한을 2.0%로 제한할 수 있다. 또한, Si 함량을 2.0% 이하로 제한하면 강표면에 Si 산화물을 형성하는 것을 방지하는 효과도 거둘 수 있다.Silicon (Si) contributes to stabilization of retained austenite as an element which suppresses precipitation of carbide in ferrite and promotes diffusion of carbon in ferrite into austenite. For this purpose, Si can be added in an amount of 0.1% or more, but when the rolling property is considered, the upper limit of the content can be limited to 2.0%. Further, when the Si content is limited to 2.0% or less, the Si oxide can be prevented from being formed on the steel surface.
Al: 0.005~1.5%Al: 0.005 to 1.5%
알루미늄(Al)은 페라이트 내 탄화물의 생성 억제를 통해 잔류 오스테나이트의 안정화에 기여하는 원소로서, 이를 위해서는 0.005% 이상으로 첨가할 수 있다. 다만, 그 함량이 1.5%를 초과하게 되면 주조시 몰드 플럭스와의 반응을 통하여 건전한 슬래브의 제조가 어려우며, 표면 산화물을 형성하여 용융도금성을 저해할 수 있으므로, Al 함량은 1.5% 이하로 제한될 수 있다.Aluminum (Al) is an element contributing to stabilization of retained austenite through inhibition of formation of carbide in ferrite, and may be added in an amount of 0.005% or more. However, if the content exceeds 1.5%, it is difficult to produce a sound slab through reaction with the mold flux during casting, and the surface oxidation can be formed to inhibit the molten conversion, so that the Al content is limited to 1.5% or less .
Mn: 1.5~8.0%Mn: 1.5 to 8.0%
망간(Mn)은 잔류 오스테나이트의 형성 및 안정화와 더불어 냉각시 페라이트 변태 억제를 위해서 변태 조직강에서 필수적인 원소이다. 또한, 오스테나이트를 충분히 확보하여 강도와 연성을 확보하기 위해서는 Mn은 1.5% 이상 포함될 수 있다. 반면 8.0%를 초과하게 되면 슬라브 및 열연공정에서 유발된 편석에 의한 밴드 형성이 과도해져 물성을 저해하는 문제가 있으므로 Mn 함량은 8.0% 이하로 제한될 수 있다.Manganese (Mn) is an indispensable element in the metamorphic steel for the formation and stabilization of retained austenite and for suppressing ferrite transformation during cooling. In order to sufficiently secure austenite to secure strength and ductility, Mn may be contained in an amount of 1.5% or more. On the other hand, when it exceeds 8.0%, the Mn content may be limited to 8.0% or less because there is a problem that the band formation due to segregation caused by the slab and hot rolling process is excessive and hinders the physical properties.
P: 0.04% 이하(0% 제외)P: 0.04% or less (excluding 0%)
인(P)은 고용강화 원소이나, 그 함량이 0.04%를 초과하면 용접성이 저하되고 강의 취성이 발생할 위험성이 커지기 때문에 그 상한을 0.04%로 한정한다.When phosphorus (P) is solid solution strengthening element, when the content exceeds 0.04%, the weldability is lowered and the risk of brittleness of steel is increased, so the upper limit is limited to 0.04%.
S: 0.015% 이하(0% 제외)S: 0.015% or less (excluding 0%)
황(S)은 강 중 불순물 원소로서, 강판의 연성 및 용접성을 저해하는 원소이다. 그 함량이 0.015%를 초과하면 강판의 연성 및 용접성을 저해할 가능성이 높아지므로, 그 상한을 0.015%로 한정한다.Sulfur (S) is an impurity element in the steel, and is an element that hinders ductility and weldability of a steel sheet. When the content exceeds 0.015%, the possibility of hindering the ductility and weldability of the steel sheet increases, so that the upper limit is limited to 0.015%.
N: 0.02% 이하(0% 제외)N: 0.02% or less (excluding 0%)
질소(N)는 오스테나이트를 안정화시키는데 유효한 작용을 하는 성분이지만, 그 함량이 0.02%를 초과하면 취성이 발생할 위험성이 크고, Al과 결합하여 AlN을 과다 석출시켜서 연주품질을 저하하므로, 0.02% 이하로 가급적 제한하는 것이 바람직하다.Nitrogen (N) is a component effective to stabilize austenite. However, when the content exceeds 0.02%, there is a great risk of occurrence of brittleness and excessively precipitates AlN by bonding with Al, As shown in Fig.
Cr: 1.5% 이하(0% 포함)Cr: 1.5% or less (including 0%)
크롬(Cr)의 함량은 1.5% 이하(0% 포함)가 바람직하다. Cr은 경화능 증가원소로서, 페라이트의 형성을 억제하는 역할을 하는 원소로서,따라서 5~20%의 잔류 오스테나이트를 확보하는데 도움이 되므로 필요에 따라 소량 첨가할 수 있다. 다만, 1.5%를 초과하는 경우에는 합금철 투입량이 과다해져서 원가 상승의 원인이 될 수 있다. 본 발명의 한가지 구현례에서는 상기 Cr은 0.7% 이하로 제한될 수도 있다.The content of chromium (Cr) is preferably 1.5% or less (including 0%). Cr is an element for increasing the hardenability and serves as an element for suppressing the formation of ferrite, and thus helps to secure 5 to 20% retained austenite, so that a small amount of Cr can be added as needed. However, if it exceeds 1.5%, the amount of iron alloy input will be excessive, which may cause cost increase. In one embodiment of the present invention, the Cr may be limited to 0.7% or less.
Mo: 0.2% 이하(0% 포함)Mo: 0.2% or less (including 0%)
몰리브덴(Mo)은 선택적으로 첨가되는 원소로서, 그 함량은 0.2% 이하(0% 포함) 로 정할 수 있다. Mo는 강도향상에 기여하는 효과가 크면서도 아연 등의 용융금속의 젖음성을 떨어뜨리지 않기 때문에 강도확보에 효과적이다. 0.2%를 초과하더라도 문제는 없으나, 더 이상 효과상승이 크지 않으므로 경제적으로 바람직하지 않다. 본 발명의 한가지 구현례에서는 상기 Mo는 0.1% 이하로 제한될 수도 있다.Molybdenum (Mo) is an element to be selectively added, and its content can be set to 0.2% or less (including 0%). Mo has a large effect of contributing to the improvement of strength and is effective in securing strength since it does not deteriorate the wettability of molten metal such as zinc. Even if it exceeds 0.2%, there is no problem, but it is not economically preferable since the effect increase is not so large any more. In one embodiment of the present invention, the Mo may be limited to 0.1% or less.
Ti: 0.1% 이하(0% 포함)Ti: 0.1% or less (including 0%)
티탄(Ti)의 함량은 0.1% 이하(0% 포함)가 바람직하다. Ti은 질화물 형성원소로써 강중 N의 농도를 감소하는 효과가 있으므로 필요에 따라 소량 첨가할 수 있다. 0.1%를 초과하면 고용 N의 제거외에 추가적인 탄화물 석출에 의한 마르텐사이트의 탄소 농도 및 강도 감소가 이루어지므로 그 상한을 0.1%로 제한할 수 있다.The content of titanium (Ti) is preferably 0.1% or less (including 0%). Ti is a nitride-forming element and has an effect of reducing the concentration of N in the steel, so that a small amount of Ti can be added as needed. If it exceeds 0.1%, the carbon concentration and the strength of the martensite are reduced due to the precipitation of additional carbide in addition to the removal of the solid solution N. Therefore, the upper limit can be limited to 0.1%.
Sb: 0.05% 이하(0% 포함)Sb: 0.05% or less (including 0%)
안티몬(Sb)은 도금 표면품질을 향상시키기 위해 선택적으로 첨가되는 성분이며, Sb의 함량은 0.05%이하 (0포함)가 바람직하다. Sb를 첨가하면 소지강판 표층부에 Sb가 농화되어 상대적으로 Si, Mn, Al등의 표면확산을 억제하므로서 전반적으로 도금성이 향상되게 된다. 그러나 0.05%를 초과하면 오히려 소둔중 Si, Mn, Al의 표면확산 억제효과가 떨어지므로 0.05%로 제한함이 바람직하다.The antimony (Sb) is a component selectively added to improve the surface quality of the plating, and the content of Sb is preferably 0.05% or less (including 0). When Sb is added, Sb is concentrated in the surface layer of the steel sheet, and the surface diffusion of Si, Mn, Al and the like is relatively suppressed, thereby improving the plating performance as a whole. However, if it exceeds 0.05%, the effect of inhibiting surface diffusion of Si, Mn and Al during annealing is deteriorated, so that it is preferable to be limited to 0.05%.
Nb: 0.1% 이하(0% 포함)Nb: 0.1% or less (including 0%)
니오븀(Nb)은 선택적으로 첨가되며, Nb의 함량은 0.1%이하가 바람직하다. Nb은 오스테나이트 입계에 탄화물 형태로 편석되어 소둔열처리시 오스테나이트 결정립의 조대화를 억제하여 강도를 증가시키며, 0.1%를 초과하는 경우에는 합금 투입량 과다에 의한 합금철 원가증가로 제한한다. Niobium (Nb) is optionally added, and the content of Nb is preferably 0.1% or less. Nb is segregated in the form of carbide in the austenite grain boundaries to suppress the coarsening of the austenite grains during the annealing heat treatment to increase the strength. When the Nb content exceeds 0.1%, the amount of alloy iron is increased due to excessive alloying amount.
B: 0.005% 이하(0% 포함)B: 0.005% or less (including 0%)
보론(B)의 함량은 0.005%이하가 바람직하다. 강중 B은 강도확보를 위해 선택적으로 첨가할수 있다. 다만, B의 함량이 0.005%를 초과하게 되면 소둔표면에 농화되어 도금성을 크게 떨어뜨린다. The content of boron (B) is preferably 0.005% or less. Steel B can be added selectively to ensure strength. However, when the content of B exceeds 0.005%, the steel is concentrated on the annealed surface and the plating ability is greatly reduced.
본 발명의 나머지 성분은 철(Fe)이다. 다만, 통상의 철강제조과정에서는 원료 또는 주위 환경으로부터 의도되지 않는 불순물들이 불가피하게 혼입될 수 있으므로, 이를 배제할 수는 없다. 이들 불순물들은 통상의 철강제조과정의 기술자라면 누구라도 알 수 있는 것이기 때문에 그 모든 내용을 특별히 본 명세서에서 언급하지는 않는다.The remainder of the present invention is iron (Fe). However, in the ordinary steel manufacturing process, impurities which are not intended from the raw material or the surrounding environment may be inevitably incorporated, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they are known to any person skilled in the art of steel making.
이하에서는 본 발명의 고강도 용융아연도금강판을 제조하는 한가지 구현례에 대해서 설명한다. 다만, 본 발명의 고강도 용융아연도금강판의 제조방법이 반드시 이하의 제조방법으로 한정되는 것은 아니다.Hereinafter, one embodiment of manufacturing the high-strength hot-dip galvanized steel sheet of the present invention will be described. However, the manufacturing method of the high strength hot dip galvanized steel sheet of the present invention is not necessarily limited to the following manufacturing method.
도 2를 통해 알 수 있듯이, 단순히 소지강판(1)을 소둔할 경우 표면에 필름 형상의 산화물(2)이 생성되므로 그 위에 도금을 실시하더라도 도금이 되지 않거나 도금층이 밀착되지 않고 도금층과 산화물 사이에 갭(5)이 발생하여 도금층(3)이 박리되는 등의 문제가 있었던 종래 기술(a)과 달리, 본 발명(b)에서는 상술한 도금성이 우수한 용융아연도금강판을 제조하기 위해, 강판의 표면에 철산화물(2)을 도포하고 소둔을 실시할 경우, 고강도 강판 내부에 존재하던 Si, Mn 또는 Al과 같은 도금방해원소가 철산화물을 환원시키면서 철산화물 근처에서 아일랜드 상의 산화물(4)을 형성시킨다. 이러한 강판에 도금을 실시하면 미도금이나 도금층(3)이 박리되는 문제를 방지할 수 있다.As can be seen from FIG. 2, when the base steel sheet 1 is simply annealed, the film-like oxide 2 is formed on the surface, so that even if plating is performed on the surface, the plating is not performed or the plating layer is not adhered, Unlike the conventional technique (a) in which the gap 5 is generated and the plating layer 3 is peeled off, in order to manufacture the hot-dip galvanized steel sheet having the above-described excellent plating property in the present invention (b) When iron oxide (2) is applied to the surface and annealing is performed, plating inhibiting elements such as Si, Mn or Al existing in the high-strength steel sheet form oxide (4) on the island near the iron oxide while reducing the iron oxide. . When such a steel sheet is plated, it is possible to prevent the problem that the unplated or the plating layer 3 is peeled off.
종래의 경우는 강판에 대하여 소둔을 실시하면 상기 도금방해원소들이 강판 표면으로 확산하여 넓은 산화물 막(film)을 형성하게 되어 도금밀착성이 크게 감소되었던 반면, 본 발명에서는 상기 도금방해원소들이 강판 표면에 분산되어 존재하는 철산화물 근처로 확산하여 산화물을 형성하기 때문에 아일랜드 상의 산화물이 형성되는 것이다. 이와 같이 표면에 아일랜드 상의 산화물이 형성된 도금용 강판에 용융아연도금을 실시할 경우에 이러한 아일랜드 상의 산화물 주변으로 강판 표면의 Fe가 노출되어 도금욕에 침지시 Fe가 용출되고 도금층의 젖음성 및 밀착성에 필수적인 Fe2Al5 합금화 억제층이 형성될 수 있다.In the conventional case, when the steel sheet is subjected to annealing, the plating interfering elements diffuse to the surface of the steel sheet to form a wide oxide film, thereby greatly reducing the plating adhesion. In the present invention, however, The oxide is formed on the island because it diffuses near the dispersed iron oxide to form an oxide. When hot-dip galvanizing is applied to a steel sheet for plating having an island-shaped oxide formed on its surface, the Fe on the surface of the steel sheet is exposed to the vicinity of the island-shaped oxide to dissolve Fe when dipped in a plating bath, An Fe 2 Al 5 alloyation inhibiting layer can be formed.
따라서, 본 발명의 제조방법은 소지강판을 준비하는 단계; 상기 준비된 소지강판에 철 산화물을 도포하는 단계; 상기 철산화물이 도포된 소지강판을 소둔하는 단계; 및 상기 소둔된 소지강판을 용융아연도금하는 단계를 포함한다.Accordingly, the manufacturing method of the present invention includes the steps of preparing a base steel sheet; Applying iron oxide to the prepared ground steel sheet; Annealing the iron oxide coated steel sheet; And hot dip galvanizing the annealed ground steel sheet.
본 발명의 한가지 구현례에서 사용되는 철 산화물은 FeO, Fe3O4, Fe2O3 중에서 선택된 1종 또는 2종 이상의 혼합물일 수 있다. 본 발명의 한가지 구현례에 따르면 이들 철 산화물은 압연유나 수지에 혼합되어 사용될 수 있는데, 이러할 경우 균일한 도포 및 코팅이 가능할 수 있다. 본 발명의 한가지 구현례에서 상기 철 산화물의 크기(구상당 직경)는 50nm 내지 5㎛일 수 있다. 즉, 냉간압연시 철 산화물이 강판 표면 직하로 용이하게 삽입될 수 있도록 하거나, 별도의 코팅 장비를 사용하여 강판에 철 산화물을 부착시키는 경우에 철 산화물이 충분한 속도를 가지고 강판 표면에 충돌할 수 있도록 하기 위하여 50nm 이상의 철 산화물을 사용할 수 있으며, 철 산화물이 소둔시 강판에서 떨어져나와 강판을 찍는 형태의 결함을 유발하는 것을 방지하기 위하여 상기 철 산화물의 크기는 5㎛ 이하로 정할 수 있다.The iron oxide used in one embodiment of the present invention may be one or a mixture of two or more selected from FeO, Fe 3 O 4 and Fe 2 O 3 . According to one embodiment of the present invention, these iron oxides can be used in combination with a rolling oil or a resin, in which case uniform coating and coating may be possible. In one embodiment of the present invention, the size (spherical equivalent diameter) of the iron oxide may be between 50 nm and 5 mu m. That is, when iron oxide can be easily inserted into the steel sheet directly under the surface of the steel sheet during cold rolling or when iron oxide is adhered to the steel sheet using a separate coating equipment, And the size of the iron oxide may be set to 5 탆 or less in order to prevent the iron oxide from falling off the steel sheet during annealing to cause a defect in the shape of a steel sheet.
또한, 본 발명의 한가지 구현례에서는 상기 철 산화물의 평균 간격을 0.5 내지 5㎛로 정할 수 있다. 상기 철 산화물의 간격을 정하는 이유는 전술한 바와 같다.Further, in one embodiment of the present invention, the average interval of the iron oxide may be set to 0.5 to 5 占 퐉. The reasons for determining the interval of the iron oxide are as described above.
본원 발명의 목적을 달성하기 위해서는 소둔 분위기를 제어하는 것이 유리하다. 즉, 본 발명에서는 소지강판 중의 Fe의 산화를 방지하면서도 Si, Mn, Al 등의 원소가 산화 반응을 일으킬 수 있도록, 소둔시의 분위기와 온도를 제어할 필요가 있다.In order to achieve the object of the present invention, it is advantageous to control the annealing atmosphere. That is, in the present invention, it is necessary to control the atmosphere and the temperature at the time of annealing so as to prevent oxidation of Fe in the base steel sheet and to cause oxidation reaction of elements such as Si, Mn, and Al.
본 발명의 한가지 구현례에 따르면, 상기 소지강판에 대한 소둔은 이슬점온도 -60~10℃로 제어된 3~70%H2-나머지N2 가스 분위기의 소둔로에서 600~950℃로 5~120초 동안 유지하는 단계를 포함할 수 있다.According to one implementation example of the invention, annealing for the carrying plate is 3 to 70% by controlling the dew point temperature of -60 ~ 10 ℃ H 2 - in annealed to the rest N 2 gas atmosphere at 600 ~ 950 ℃ 5 ~ 120 Lt; RTI ID = 0.0 > seconds. ≪ / RTI >
즉, 강판의 Fe는 산화되지 않으면서도 Si, Mn 또는 Al 등의 원소는 산화되도록 할 필요가 있는데, 본 발명의 한가지 구현례에서는 이를 위해서는 소둔시 이슬점 온도를 10℃ 이하로 유지할 수 있다. 또한, 현실적인 생산라인에서의 분위기 유지 능력을 고려할 경우, 본 발명의 한가지 구현례에서 상기 소둔시 이슬점 온도는 -60℃ 이상으로 정할 수 있다.That is, it is necessary to oxidize elements such as Si, Mn or Al without oxidizing the Fe of the steel sheet. In one embodiment of the present invention, the dew point temperature can be maintained at 10 ° C or less during annealing. Also, considering the ability to maintain the atmosphere in a realistic production line, in one embodiment of the present invention, the dew point temperature during annealing may be set at -60 캜 or higher.
또한, 철 산화물이 Si, Mn 또는 Al에 의해 환원되면서 이들 원소가 산화되어 산화물을 형성하도록 하기 위해서는 소둔시 분위기 가스중 수소함량을 부피%로 3% 이상으로 정할 수 있다. 수소 함량이 높아진다고 하더라도 특별한 기술적인 문제는 발생하지 아니하나, 본 발명의 한가지 구현례에서는 경제성을 감안하여 상기 수소함량을 70% 이하로 정할 수 있다.Further, in order to oxidize these elements to form oxides while the iron oxide is reduced by Si, Mn or Al, the hydrogen content in the atmospheric gas at the time of annealing can be set to 3% or more by volume. Even if the hydrogen content is increased, there is no particular technical problem. However, in one embodiment of the present invention, the hydrogen content can be set to 70% or less in consideration of economical efficiency.
또한, 충분한 반응효과를 얻기 위해서는 상기 소둔시의 강판 온도는 600℃ 이상으로 할 수 있다. 다만, 소둔로의 수명을 고려할 경우 상기 강판 온도는 950℃ 이하로 정할 수 있다. 또한, 본 발명의 한가지 구현례에서는 상기 소둔 온도범위 내에서 강판의 재결정을 도모할 수 있다.Further, in order to obtain a sufficient reaction effect, the temperature of the steel sheet at the time of annealing may be 600 ° C or higher. However, considering the lifetime of the annealing furnace, the steel sheet temperature may be set at 950 ° C or lower. In one embodiment of the present invention, the steel sheet can be recrystallized within the annealing temperature range.
충분한 효과를 얻기 위해서 상기 소둔시 목표 온도에 도달한 이후의 시간은 5초 이상으로 정할 수 있다. 소둔시간이 다소 길더라도 큰 문제는 없으나, 비용상승을 초래할 수 있으므로 본 발명의 한가지 구현례에서 상기 소둔시간은 120초 이하로 제한할 수 있다. 재결정 소둔까지 겸하는 경우에는 상기 소둔시간은 균일한 재결정 조직을 얻는데도 도움이 될 수 있다.In order to obtain a sufficient effect, the time after reaching the target temperature for annealing may be set to 5 seconds or more. The annealing time may be limited to 120 seconds or less in one embodiment of the present invention since the annealing time may be somewhat long, but it may cause a rise in cost. In the case of doubling up to recrystallization annealing, the annealing time may also be helpful in obtaining a uniform recrystallized structure.
본 발명이 소둔 단계 이후에는 냉각 단계가 후속할 수 있다. 도금성을 확보하기 위해서 냉각조건을 특별히 제한할 필요는 없으나, 도금강판의 미세조직과 강도 및 연신율을 제어할 경우에는 250~550℃까지 평균 냉각속도 5~100℃/초로 냉각을 실시할 수 있다. 예를 들면, 냉각정지온도가 높거나 냉각속도가 너무 낮으면 강도가 미흡할 수 있으며, 반대로 냉각정지온도가 너무 낮거나 냉각속도가 너무 높으면 연신율이 나빠질 수 있다. 본 발명의 한가지 구현례에서 상기 냉각은 1차 냉각과 2차 냉각으로 나누어 실시할 수 있으며 2차 냉각속도는 1차 냉각속도보다 클 수 있다. 본 발명의 한가지 구현례에서 상기 1차 냉각은 600~700℃까지 수행될 수 있으며, 그 이후부터 2차 냉각이 수행될 수 있다.After the annealing step of the present invention, a cooling step may follow. In order to secure the plating property, there is no particular limitation on the cooling condition, but when controlling the microstructure, strength and elongation of the coated steel sheet, cooling can be carried out at an average cooling rate of 5 to 100 DEG C / sec. . For example, if the cooling stop temperature is high or the cooling speed is too low, the strength may be insufficient. Conversely, if the cooling stop temperature is too low or the cooling speed is too high, the elongation rate may be deteriorated. In one embodiment of the present invention, the cooling may be performed in a primary cooling mode and a secondary cooling mode, and the secondary cooling rate may be greater than the primary cooling rate. In one embodiment of the present invention, the primary cooling may be performed to 600 to 700 占 폚, after which secondary cooling may be performed.
또한, 본 발명의 한가지 구현례에 따르면 소둔 단계 이전에 강판을 냉간압연하는 단계를 더 포함할 수 있다. 즉, 표면에 철 산화물이 도포된 강판을 냉간압연할 경우 상기 철 산화물이 냉연강판의 표면 직하로 삽입될 수 있어서, 이를 통하여 Si, Mn 또는 Al 등의 원소가 철 산화물 주위에서 산화물을 형성하는 것이 더욱 용이할 수 있다. Further, according to one embodiment of the present invention, the method may further include a step of cold-rolling the steel sheet before the annealing step. That is, when the steel sheet coated with iron oxide on its surface is cold-rolled, the iron oxide can be inserted right under the surface of the cold-rolled steel sheet, and an element such as Si, Mn or Al forms an oxide around the iron oxide Can be more easily achieved.
또한, 본 발명의 또한가지 구현례에 따르면 별도의 코팅 장비를 사용하여 철 산화물을 도포하여 강판 표면에 강고하게 결합시킬 수 있다. 즉, 본 발명의 한가지 구현례에서는 용사코팅(thermal spray)이나 AD(Aerosol Deposition) 코팅 등과 같이 철 산화물을 분사하여 코팅할 수 있는 장비를 이용하여 강판 표면에 철 산화물을 분사하여 도포할 수 있으며, 이러할 경우에는 코팅 후에 냉간압연을 실시하지 않아도 철 산화물이 강판 표면에 강고하게 결합될 수 있다.Further, according to further embodiments of the present invention, iron oxide may be applied using a separate coating equipment to firmly bond to the surface of the steel sheet. That is, in one embodiment of the present invention, iron oxide may be sprayed onto the surface of a steel sheet by using an apparatus capable of spraying and coating iron oxide such as thermal spray or AD (Aerosol Deposition) coating, In this case, the iron oxide can be firmly bonded to the steel sheet surface without cold rolling after coating.
또한, 본 발명의 한가지 구현례에서는 필요에 따라 상기 철 산화물을 강판 표면에 도포하기 전에 강판 표면을 산세하는 단계를 더 포함할 수 있다. 산세는 통상의 방법으로 이루어질 수 있으며 특별히 그 조건을 제한하지 아니한다.In one embodiment of the present invention, the method may further include the step of pickling the surface of the steel sheet before applying the iron oxide to the surface of the steel sheet, if necessary. The pickling can be done in the usual way and does not limit the conditions in particular.
상술한 바와 같이, 소둔 단계 이후에는 상기 강판을 용융아연도금하는 단계가 후속할 수 있다. 용융아연도금방법은 특별히 제한하지 아니하나, 본 발명의 한가지 구현례에서 도금되는 금속으로서 아연을 채택할 경우, Al함량이 0.13~0.3% 포함되고 나머지는 Zn과 불가피한 불순물로 구성되고 440~500℃의 온도로 유지된 아연도금욕에 강판을 침지한 후 꺼내어 도금부착량을 조절한 후 냉각하여 융융 아연도금강판을 제조할 수 있다. 도금욕 Al함량이 0.13% 미만일 경우 소지철과 도금층 계면에 형성되는 Fe-Al합금상 형성이 억제되어 도금박리가 발생하기 때문에 하한은 0.13%로 제한함이 바람직하다. 또한 Al함량이 0.3%를 초과하면 도금층내 Al함량이 증가하여 용접성을 떨어뜨리는 문제가 있다.As described above, after the annealing step, the step of hot-dip galvanizing the steel sheet may follow. The hot dip galvanizing method is not particularly limited, but in one embodiment of the present invention, when zinc is employed as the metal to be plated, it contains 0.13 to 0.3% of Al and the remainder is composed of Zn and unavoidable impurities, The steel sheet is immersed in a galvanizing bath maintained at a predetermined temperature, and then taken out to regulate the amount of deposited metal, followed by cooling to produce a hot-dip galvanized steel sheet. When the Al content of the plating bath is less than 0.13%, formation of the Fe-Al alloy phase formed at the interface between the base iron and the plating layer is suppressed and plating separation occurs. Therefore, the lower limit is preferably limited to 0.13%. When the Al content is more than 0.3%, the Al content in the plating layer increases and the weldability is deteriorated.
본 발명의 한가지 구현례에 따르면, 아연 도금을 실시할 경우 강판은 도금 전에 400~550℃로 재가열될 수 있다. 즉, Fe의 용출에 의하여 형성되는 합금화 억제층이 지연없이 형성되도록 하기 위해서는 상기 재가열 온도가 400℃ 이상일 수 있다. 다만, 온도가 너무 높을 경우에는 일부 고강도 강의 경우 상변태가 발생하여 원하는 재질을 충족시킬 수 없으므로, 상기 재가열 온도의 상한은 550℃로 정할 수 있다.According to one embodiment of the present invention, when zinc plating is performed, the steel sheet can be reheated to 400 to 550 ° C before plating. That is, in order to form the alloying suppressing layer formed by elution of Fe without delay, the reheating temperature may be 400 캜 or higher. However, if the temperature is too high, a phase transformation may occur in some high-strength steels and the desired material can not be satisfied. Therefore, the upper limit of the reheating temperature may be set to 550 ° C.
도금욕 온도는 440~500℃로 제한한다. 440℃ 미만에서는 아연의 점도가 증가하여 도금욕내의 롤의 구동성이 떨어지고 500℃를 초과하면 아연의 증발이 증가하기 때문에 바람직하지 않다.The plating bath temperature is limited to 440 to 500 ° C. Below 440 캜, the viscosity of the zinc increases and the rollability of the roll in the plating bath lowers. When the temperature exceeds 500 캜, the evaporation of zinc increases, which is not preferable.
상기와 같은 강성분 및 제조방법으로 제조된 용융아연도금강판은 소지강판 표면으로부터 깊이방향으로 5㎛ 이내에 Si, Mn, Al등에 의해 일부 또는 전부가 환원된 철 산화물이 존재하고 그 근처에서 Si, Mn, Al등이 농화되어 산화물 형태로 존재한다.In the hot-dip galvanized steel sheet produced by the above-described steel component and manufacturing method, iron oxide partially or wholly reduced by Si, Mn, Al or the like is present within 5 탆 in the depth direction from the surface of the steel sheet and Si, Mn , Al and the like are concentrated and exist in an oxide form.
본 발명에서 철 산화물이 도포되는 소지강판은 열연강판 또는 냉연강판일 수 있다. 본 발명이 소지강판은 통상의 열간압연 또는 냉간압연을 통하여 제조될 수 있으며, 특별히 그 제조조건을 제한하지 않으나, 본 발명의 한가지 구현례에 따른 제한적이지 않은 예를 든다면 다음과 같다.In the present invention, the base steel sheet to which the iron oxide is applied may be a hot-rolled steel sheet or a cold-rolled steel sheet. The base steel sheet of the present invention can be produced by conventional hot rolling or cold rolling, and the manufacturing conditions are not particularly limited, but the following is a non-limiting example according to one embodiment of the present invention.
본 발명의 한가지 구현례에서는 상기 조성을 만족하는 강 슬라브를 1100~1300℃의 온도로 재가열하는 단계; 상기 재가열된 강 슬라브를 마무리 열간압연 온도 Ar3이상의 온도로 사상압연을 마무리하는 단계; 상기 열간 압연된 열연강판을 700℃ 이하의 온도로 권취하는 단계에 의하여 열연강판을 제조할 수 있으며, 필요에 따라 상기 열연강판을 산세후 냉간 압연하는 단계에 따라 냉연강판을 제조할 수 있다. 이하, 각 단계별로 상세히 설명한다.In one embodiment of the invention, reheating the steel slab satisfying the composition to a temperature between 1100 and 1300 ° C; Finishing the reheated steel slab to a finish temperature of the finishing hot rolling temperature Ar3 or higher; The hot-rolled steel sheet may be manufactured by winding the hot-rolled steel sheet at a temperature of 700 ° C or less. If necessary, the cold-rolled steel sheet may be manufactured by pickling the hot-rolled steel sheet followed by cold rolling. Hereinafter, each step will be described in detail.
먼저, 상기 조성을 만족하는 슬라브를 1100~1300℃의 온도범위로 재가열한다. 상기 재가열 온도가 1100℃ 미만이면 열간압연 하중이 급격히 증가하는 문제가 발생하며, 1300℃를 초과하는 경우에는 재가열 비용의 상승 및 표면 스케일 양이 증가하므로 1300℃ 이하로 제한한다.First, the slab satisfying the above composition is reheated to a temperature range of 1100 to 1300 ° C. If the reheating temperature is lower than 1100 ° C, there is a problem that the hot rolling load sharply increases. If the reheating temperature is higher than 1300 ° C, the reheating cost increases and the surface scale amount increases.
상기 재가열된 슬라브의 마무리 열간압연 온도를 Ar3(오스테나이트를 냉각시에 페라이트가 출현하기 시작하는 온도)이상으로 한정하는데, 이는 Ar3 미만에서는 페라이트+오스테나이트의 2상역 혹은 페라이트역 압연이 이루어져서 혼립조직이 만들어지며, 이로 인한 열간 압연하중의 변동으로 인한 형상불량이나 판파단 등의 문제가 우려되기 때문이다.The finishing hot rolling temperature of the reheated slab is limited to not less than Ar3 (the temperature at which ferrite starts to appear when the austenite is cooled), which is below the Ar3, and the ferrite + And there is a fear of problems such as defective shape or sheet breakage due to the fluctuation of the hot rolling load due to this.
상기 열간압연을 행한 후 강판을 권취한다. 이때, 권취온도가 700℃를 초과하는 경우에, 강판 표면의 산화막이 과다하게 생성되어 결함을 유발할 수 있으므로 상기 권취온도를 700℃ 이하로 제한한다. After the hot rolling, the steel sheet is wound. At this time, when the coiling temperature exceeds 700 占 폚, the oxide film on the surface of the steel sheet may be excessively generated to cause defects, so that the coiling temperature is limited to 700 占 폚 or less.
상술한 과정에 의하여 열연강판을 얻을 수 있으며 그 표면에 상술한 바와 같이 철 산화물을 도포하여 소둔 및 도금하는 과정에 의하여 본 발명의 용융아연도금강판을 얻을 수 있다. 다만, 필요에 따라서는 상기 열연강판에 산세 및 냉간압연을 실시하여 냉연강판으로 한 후 그 표면에 철 산화물을 도포하여 소둔 및 도금하는 과정에 의하여 본 발명의 용융아연도금강판을 얻을 수도 있다. 산세 및 냉간압연 조건에 대해서는 특별히 제한하지 않으며 통상의 방법을 사용할 수 있다.The hot-rolled steel sheet can be obtained by the above-mentioned process, and the hot-dip galvanized steel sheet of the present invention can be obtained by applying the iron oxide on the surface of the hot-rolled steel sheet, annealing and plating the surface. However, the hot-dip galvanized steel sheet of the present invention may be obtained by subjecting the hot-rolled steel sheet to pickling and cold rolling to obtain a cold-rolled steel sheet, coating the surface with iron oxide, annealing and plating. The pickling and cold rolling conditions are not particularly limited and ordinary methods can be used.
이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명한다. 다만, 하기하는 실시예는 본 발명을 예시하여 구체화하기 위한 것일 뿐, 본 발명의 권리범위를 제한하기 위한 것이 아니라는 점에 유의할 필요가 있다. 본 발명의 권리범위는 청구범위에 기재된 사항 및 이로부터 합리적으로 유추되는 사항에 의하여 결정되는 것이기 때문이다.Hereinafter, the present invention will be described more specifically by way of examples. It should be noted, however, that the following examples are intended to illustrate and specify the present invention and not to limit the scope of the present invention. Since the scope of the present invention is determined by the matters set forth in the claims and the matters reasonably deduced therefrom.
(실시예)(Example)
하기 표 1의 조성을 갖는 강을 용해하여 슬라브를 제조하였다. 제조된 슬라브는 1200℃에서 1시간 유지후, Ar3 이상의 온도인 900℃에서 마무리 압연후 600℃까지 냉각한 후 권취과정을 모사하기 위해 보온로에서 1시간 동안 유지하여 100℃까지 로냉을 실시하였다.The steel having the composition shown in Table 1 below was melted to prepare a slab. The produced slab was maintained at 1200 ° C for 1 hour, cooled to 600 ° C at 900 ° C, which is the temperature of Ar3 or higher, and then cooled to 100 ° C by keeping it in a warming furnace for 1 hour to simulate the winding process.
냉각이 완료된 열연강판은 60℃, 17vol% HCl 용액으로 30초간 산세를 실시하여 강판의 스케일을 제거하였다.The cold-rolled hot-rolled steel sheet was pickled at 60 ° C in a 17% by volume HCl solution for 30 seconds to remove the scale of the steel sheet.
산세가 완료된 강판에 대하여 하기 표 2을 도포하고, 철 산화물이 도포된 강판을 50%의 압하율로 냉간압연하였다. 냉간압연에 의해 철 산화물이 강판 표면에 고르게 분포되어 있는 것을 확인할 수 있었다. 이때, 철 산화물을 보다 균일하게 분포시키기 위하여 철 산화물을 압연유와 혼합하여 사용하였다.The pickled steel sheet was coated with the following Table 2, and the steel sheet coated with the iron oxide was cold-rolled at a reduction ratio of 50%. It was confirmed that the iron oxide was evenly distributed on the surface of the steel sheet by cold rolling. At this time, iron oxide was mixed with rolling oil to distribute the iron oxide more uniformly.
이후 상기 강판에 대하여, 표 3에 기재된 조건으로 소둔(5%수소+95%질소분위기에서 실시) 및 용융아연도금을 실시하였다. 표 3의 도금욕 조성에서 Al을 제외한 잔부는 Zn으로 하였다. 도금부착량은 편면기준 60g/m2으로 조절하고 도금욕에 인입되기 전 강판을 재가열하여 온도를 470℃로 조절하였다.Then, the steel sheet was subjected to annealing (conducted in a 5% hydrogen + 95% nitrogen atmosphere) and hot-dip galvanizing under the conditions shown in Table 3. In the plating bath composition of Table 3, the remainder excluding Al was Zn. The amount of plating adhered was adjusted to 60 g / m 2 on one side, and the steel sheet was reheated before entering the plating bath to adjust the temperature to 470 ° C.
도금이 완료된 도금강판의 표면의 미도금등 표면품질을 육안으로 관찰하여 표 4에 나타내었다. 표에서 표면품질과 관련하여 직경 2mm를 초과하는 미도금 부위가 관찰되지 않을 경우에는 ○로, 직경 2mm를 초과하는 미도금 부위가 관찰될 경우에는 ×로 나타내었다. 또한 강판의 도금층 밀착성을 평가하기 위해 강판 표면에 자동차 구조용 접착제를 도포하고 건조한 후 90도로 굽힌 후 도금강판이 접착제에 떨어져 나오는지를 확인하여 밀착성을 평가하였다. 도금박리가 없을 경우를 ○로, 관찰될 경우에는 ×로 나타내었다. Surface quality such as uncoated surface of the plated steel sheet after plating was visually observed and shown in Table 4. In the table, when the uncoated portion exceeding 2 mm in diameter was not observed in relation to the surface quality, the symbol was marked as & cir & when the uncoated portion exceeding 2 mm in diameter was observed. In addition, to evaluate the adhesion of the steel sheet to the plating layer, the automotive structural adhesive was applied to the surface of the steel sheet, and after drying, the sheet was bent at 90 degrees, and the adhesion of the steel sheet to the adhesive was evaluated. The case where no plating peeling is observed is indicated by?, And the case where it is observed is indicated by?.
| 강종Steel grade | CC | SiSi | Sol.AlSol.Al | MnMn | PP | SS | NN | CrCr |
Ti | NbNb |
| 강1River 1 | 0.120.12 | 1.11.1 | 0.030.03 | 2.752.75 | 0.0110.011 | 0.0010.001 | 0.0050.005 | 0.0030.003 | 0.0020.002 | |
|
강2 |
0.220.22 | 1.471.47 | 0.030.03 | 2.172.17 | 0.0060.006 | 0.0020.002 | 0.0050.005 | -- | -- |
| 구분division | 강종Steel grade | 철산화물Iron oxide | ||
| 종류Kinds | 크기 분포Size distribution |
평균간격 | ||
| 발명예1Inventory 1 |
강1 |
Fe2O3Fe2O3 |
200nm~800nm200 nm to 800 |
2~3μm2 ~ |
| 발명예2Inventory 2 |
강1 |
Fe3O4Fe3O4 |
200nm~400nm200 nm to 400 |
2~3μm2 ~ 3μm |
| 비교예1Comparative Example 1 | 강1River 1 | -- | -- | -- |
|
발명예3 |
강2 |
Fe2O3Fe2O3 |
200nm~800nm200 nm to 800 |
2~3μm2 ~ 3μm |
| 발명예4Honorable 4 |
강2 |
Fe3O4Fe3O4 |
200nm~400nm200 nm to 400 |
2~3μm2 ~ |
| 발명예5Inventory 5 |
강2 |
Fe2O3Fe2O3 | 200nm~800nm200 nm to 800 nm | 10μm 이상10μm or more |
| 비교예2Comparative Example 2 | 강2River 2 | -- | -- | -- |
| 구분division | 강종Steel grade | 소둔 공정Annealing process | 도금공정Plating process | ||||||
| 소둔로 이슬점 온도(℃)Annealing temperature dew point temperature (℃) | 소둔온도(℃)Annealing temperature (캜) | 유지시간(초)Holding Time (sec) | 냉각정지온도(℃)Cooling stop temperature (℃) | 평균 냉각속도(℃/초)Average cooling rate (° C / sec) | 재가열온도(℃)Reheating temperature (℃) | 도금욕온도(℃)Plating bath temperature (캜) | 도금욕Al 농도(중량%)Plating bath Al concentration (% by weight) | ||
|
발명예1 |
강1River 1 | -50-50 | 790790 | 6565 | 320320 | 2222 | 490490 | 456456 | 0.220.22 |
|
발명예2 |
강1River 1 | -50-50 | 790790 | 6565 | 320320 | 2222 | 490490 | 456456 | 0.220.22 |
| 비교예1Comparative Example 1 | 강1River 1 | -50-50 | 790790 | 6565 | 320320 | 2222 | 490490 | 456456 | 0.220.22 |
|
발명예3 |
강2River 2 | -50-50 | 850850 | 7676 | 320320 | 2626 | 490490 | 456456 | 0.220.22 |
| 발명예4Honorable 4 | 강2River 2 | -50-50 | 850850 | 7676 | 320320 | 2626 | 490490 | 456456 | 0.220.22 |
|
발명예5 |
강2River 2 | -50-50 | 850850 | 7676 | 320320 | 2626 | 490490 | 456456 | 0.220.22 |
| 비교예2Comparative Example 2 | 강2River 2 | -50-50 | 850850 | 7676 | 320320 | 2626 | 490490 | 456456 | 0.220.22 |
| 구분division | 산화물 분석 결과Oxide analysis result | 도금품질Plating quality | 도금밀착성Plating adhesion | |||
| 원상당 직경 분포Circle equivalent diameter distribution | 평균 간격Average spacing | 형태shape |
산화물 종류 | |||
| 발명예1Inventory 1 | 800nm 이하800 nm or less | 2~3㎛2 ~ 3㎛ | 아일랜드Ireland | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ○○ |
|
발명예2 |
400nm 이하400 nm or less | 2~3㎛2 ~ 3㎛ | 아일랜드Ireland | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ○○ |
| 비교예1Comparative Example 1 | 해당없음Not applicable | 해당없음Not applicable | 필름film | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ×× |
|
발명예3 |
800nm 이하800 nm or less | 2~3㎛2 ~ 3㎛ | 아일랜드Ireland | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ○○ |
| 발명예4Honorable 4 | 400nm 이하400 nm or less | 2~3㎛2 ~ 3㎛ | 아일랜드Ireland | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ○○ |
|
발명예5 |
800nm 이하800 nm or less | 10㎛ 이상10 μm or more | 아일랜드+필름 혼합Ireland + film mix | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ○○ | ×× |
| 비교예2Comparative Example 2 | 해당없음Not applicable | 해당없음Not applicable | 필름film | Si,Mn,Al 복합산화물Si, Mn, Al composite oxides | ×× | ×× |
실시예에서 발명예1, 2, 비교예 1의 강 조성, 소둔 및 도금 조건 등은 모두 동일하게 적용하였으며, 단지 Fe 산화물을 사용 여부에 따라 발명예와 비교예로 구분된다. 마찬가지로, 발명예 3, 4, 5 및 비교예 2 역시 강 조성, 소둔 조건, 도금 조건 등을 모두 동일하게 적용하되 Fe 산화물 사용여부를 달리 설정하였다. In the examples, the steel composition, annealing and plating conditions of Inventive Examples 1 and 2 and Comparative Example 1 were all applied equally, and Fe oxide was classified into the inventive example and the comparative example depending on whether or not Fe oxide was used. Likewise, Inventive Samples 3, 4 and 5 and Comparative Example 2 were also applied in the same manner for steel composition, annealing condition, plating condition, and the like, but using Fe oxide was set differently.
발명예에서는 철 산화물이 강판 표면에서부터 삽입되어 소둔되었기 때문에 강판 표면으로부터 깊이 5㎛ 이내에 상기 철 산화물이 존재한 이후 상기 철 산화물을 Si, Mn, Al 등의 원소가 환원을 하게 되는 것을 확인할 수 있었다. 따라서, 강판 표면으로부터 깊이 5㎛ 이내에 철 산화물이 환원된 영역이 존재하였으며, 그 근처에서 Si, Mn 및 Al의 복합 산화물이 존재하고 있었다. 일부 Si, Mn, Al의 산화물 중 일부는 강판 표면에도 존재하나 그 위에 환원된 철이나 철 산화물 등이 존재하고 있기 때문에 용융아연도금하여도 미도금의 문제나 도금 밀착성이 저하되는 문제는 없었다.In the present invention, since iron oxide was inserted and annealed from the surface of the steel sheet, it was confirmed that the iron oxide was reduced to elements such as Si, Mn and Al after the iron oxide was present within a depth of 5 μm from the surface of the steel sheet. Therefore, there was a region where the iron oxide was reduced to a depth of 5 占 퐉 from the surface of the steel sheet, and a complex oxide of Si, Mn and Al was present in the vicinity. Some of the oxides of Si, Mn, and Al are also present on the surface of the steel sheet, but there is no problem that the problem of unplated and adhesion of the plating deteriorates even when hot-dip galvanizing is performed because reduced iron or iron oxide exists thereon.
그러나, 발명예5 와 같이 철 산화물을 적용하여도 철 산화물의 평균 간격이 10㎛ 이상 떨어지면 소둔후 표면산화물의 형태가 아일랜드상과 필름상의 혼합으로 형성되면서 도금층 밀착성이 저하되는 문제가 발생하였다. However, even when iron oxide is applied as in Example 5, if the average spacing of the iron oxide is less than 10 탆, the surface oxide after the annealing is formed as a mixture of the island phase and the film, and the adhesion of the plating layer is deteriorated.
또한, 산화물을 사용하지 않았던 비교예의 경우에는 소지강판의 표면에 필름 형태의 Si, Mn, Al 등의 산화물이 넓게 존재하여, 도금층 밀착성 혹은 표면품질, 도금층 밀착성 모두 확보하기가 어렵다. In the case of the comparative example in which no oxide was used, oxides such as Si, Mn and Al in the form of film are widely present on the surface of the base steel sheet, and it is difficult to secure the adhesion of the plating layer or the surface quality and the adhesion of the plating layer.
표 4에서 비교예 1은 표면품질을 확보하지 못하고 비교예 2는 표면품질과 도금층 밀착성 모두를 확보하지 못한 원인은 비교예 2가 상대적으로 Si의 함량이 많으며 소둔온도도 비교예 1 보다 약 60℃ 높아 소둔중 표면으로 확산되는 Si 및 Mn의 양이 많았기 때문으로 추정된다.In Table 4, the surface quality of Comparative Example 1 was not ensured. In Comparative Example 2, the reason why the surface quality and the adhesion of the plating layer were not ensured was that the content of Si was relatively high in Comparative Example 2 and the annealing temperature was about 60 ° C And the amount of Si and Mn diffusing to the surface during annealing was high.
따라서, 본 발명의 유리한 효과를 확인할 수 있었다.Therefore, the advantageous effects of the present invention can be confirmed.
Claims (24)
- 소지강판;Base steel sheet;소지강판 위에 형성된 용융아연도금층; 및A hot dip galvanized layer formed on the base steel sheet; And상기 소지강판의 표면 및/또는 소지강판의 표면으로부터 깊이 5㎛ 이내에서 아일랜드 상으로 형성된 Si, Mn 및 Al 중에서 선택된 1종 이상의 원소의 산화물을 포함하는 용융아연도금강판.And an oxide of at least one element selected from the group consisting of Si, Mn and Al formed in an island shape at a depth of 5 mu m or less from the surface of the base steel sheet and / or the surface of the base steel sheet.
- 제 1 항에 있어서, 상기 아일랜드 상 산화물의 원상당 직경은 5㎛ 이하인 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 1, wherein the circle equivalent diameter of the island-shaped oxide is 5 占 퐉 or less.
- 제 1 항에 있어서, 상기 아일랜드 상 산화물의 평균 간격이 0.1㎛ 이상인 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 1, wherein the average interval of the island-shaped oxides is 0.1 탆 or more.
- 제 1 항에 있어서, 상기 아일랜드 상의 산화물들은 Si, Mn 및 Al 중에서 선택된 하나의 원소의 산화물, 이들 중 둘 이상의 원소들의 복합산화물 또는 각 원소들의 산화물의 복합체(cluster)인 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 1, wherein the oxides on the island are a composite of an oxide of one element selected from Si, Mn and Al, a composite oxide of two or more of the elements, or an oxide of each element.
- 제 1 항에 있어서, 상기 아일랜드 상의 산화물과 용융아연도금층 사이에는 철 산화물 또는 철(Fe) 입자 또는 이들의 복합체가 존재하는 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 1, wherein iron oxide or iron (Fe) particles or a composite thereof is present between the island-shaped oxide and the hot-dip galvanized layer.
- 제 5 항에 있어서, 상기 철 산화물, 철 입자 또는 이들의 복합체가 50nm~5㎛ 정도의 크기를 가지는 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 5, wherein the iron oxide, iron particles, or a composite thereof has a size of about 50 nm to 5 탆.
- 제 1 항 내지 제 6 항 중 어느 한 항에 있어서, 소지강판이 Si, Mn 및 Al을 함량 합계로 3.5중량% 이상 포함하는 용융아연도금강판.The hot-dip galvanized steel sheet according to any one of claims 1 to 6, wherein the base steel sheet contains Si, Mn and Al in an amount of 3.5 wt% or more in total.
- 제 7 항에 있어서, 소지강판이 Si: 0.5% 이상, Mn: 2.0% 이상, Al: 1.0% 이상 중 1종 이상을 포함하는 용융아연도금강판.The hot-dip galvanized steel sheet according to claim 7, wherein the base steel sheet comprises at least one of Si: at least 0.5%, Mn: at least 2.0%, and Al: at least 1.0%.
- 제 8 항에 있어서, 소지강판이 중량%로, C: 0.05~0.3%, Si: 0.1~2.0%, Sol. Al: 0.005~1.5%, Mn: 1.5~8.0%, P: 0.04% 이하(0%는 제외), S: 0.015% 이하(0%는 제외), N: 0.02% 이하(0%는 제외), Cr: 1.5%이하(0%포함), Mo: 0.2% 이하(0% 포함), Ti: 0.1% 이하(0% 포함), Sb: 0.05% 이하(0% 포함), Nb: 0.1% 이하(0% 포함), B: 0.005% 이하(0% 포함) 을 포함하는 조성을 가지는 용융아연도금강판.The steel sheet according to claim 8, wherein the base steel sheet contains 0.05 to 0.3% of C, 0.1 to 2.0% of Si, 0.1 to 2.0% of Si, Al: 0.005 to 1.5%, Mn: 1.5 to 8.0%, P: not more than 0.04% (excluding 0%), S: not more than 0.015% (excluding 0%), N: not more than 0.02% Cr: not more than 1.5% (including 0%), Mo: not more than 0.2% (including 0%), Ti: not more than 0.1% (including 0%), Sb: not more than 0.05% 0%) and B: 0.005% or less (including 0%).
- 소지강판을 준비하는 단계; Preparing a base steel sheet;상기 준비된 소지강판에 철 산화물을 도포하는 단계; Applying iron oxide to the prepared ground steel sheet;상기 철산화물이 도포된 소지강판을 소둔하는 단계; 및 Annealing the iron oxide coated steel sheet; And상기 소둔된 소지강판을 용융아연도금하는 단계를 포함하는 용융아연도금강판의 제조방법.And subjecting the annealed ground steel sheet to hot dip galvanizing.
- 제 10 항에 있어서, 상기 철 산화물은 FeO, Fe3O4, Fe2O3 중에서 선택된 1종 또는 2종 이상의 혼합물인 용융아연도금강판의 제조방법.The method of producing a hot-dip galvanized steel sheet according to claim 10, wherein the iron oxide is one or a mixture of two or more selected from FeO, Fe 3 O 4 , and Fe 2 O 3 .
- 제 11 항에 있어서, 상기 철 산화물은 압연유나 수지에 혼합되어 사용되는 용융아연도금강판의 제조방법.The method of manufacturing a hot-dip galvanized steel sheet according to claim 11, wherein the iron oxide is mixed with a rolling oil or a resin.
- 제 11 항에 있어서, 상기 철 산화물을 도포하는 단계는 철 산화물을 강판 표면에 분사하여 도포하는 단계인 용융아연도금강판의 제조방법.12. The method of manufacturing a hot-dip galvanized steel sheet according to claim 11, wherein the step of applying the iron oxide is a step of spraying and coating an iron oxide on the surface of the steel sheet.
- 제 11 항에 있어서, 상기 철 산화물의 크기가 50nm 내지 5㎛인 용융아연도금강판의 제조방법.12. The method of manufacturing a hot-dip galvanized steel sheet according to claim 11, wherein the iron oxide has a size of 50 nm to 5 占 퐉.
- 제 10 항에 있어서, 상기 철 산화물의 평균 간격이 0.1 내지 5㎛인 용융아연도금강판의 제조방법.11. The method for producing a hot-dip galvanized steel sheet according to claim 10, wherein the average interval of the iron oxide is 0.1 to 5 mu m.
- 제 10 항에 있어서, 상기 소둔은 이슬점온도 -60~10℃로 제어된 3~70%H2-N2 가스 분위기의 소둔로에서 600~950℃로 5~120초 동안 유지하여 수행되는 용융아연도금강판의 제조방법.The method according to claim 10, wherein the annealing is performed in an annealing furnace in a 3 to 70% H 2 -N 2 gas atmosphere controlled at a dew point temperature of -60 to 10 ° C for 5 to 120 seconds at 600 to 950 ° C, A method of manufacturing a plated steel sheet.
- 제 10 항에 있어서, 상기 소둔 단계 이후에 강판을 250~550℃까지 5~100℃/초의 평균 냉각속도로 냉각하는 단계를 더 포함하는 용융아연도금강판의 제조방법.The method of manufacturing a hot dip galvanized steel sheet according to claim 10, further comprising, after the annealing step, cooling the steel sheet to an average cooling rate of from 5 to 100 ° C / second from 250 to 550 ° C.
- 제 10 항에 있어서, 상기 소둔 단계 이전에 강판을 냉간압연하는 단계를 더 포함하는 용융아연도금강판의 제조방법.The method of manufacturing a hot-dip galvanized steel sheet according to claim 10, further comprising a step of cold-rolling the steel sheet before the annealing step.
- 제 10 항에 있어서, 상기 용융아연도금하는 단계는 Al함량이 0.13~0.3% 포함되고 나머지는 Zn과 불가피한 불순물로 구성된 아연도금욕을 사용하여 도금욕 온도 440~500℃로 유지된 도금욕에 침지하여 수행되는 용융아연도금강판의 제조방법.The method of claim 10, wherein the hot dip galvanizing step comprises immersing in a plating bath maintained at a plating bath temperature of 440 to 500 DEG C by using a galvanizing bath comprising 0.13 to 0.3% of Al and the balance of Zn and unavoidable impurities Wherein the hot-dip galvanized steel sheet is a hot-dip galvanized steel sheet.
- 제 10 항에 있어서, 상기 소지강판은The method as claimed in claim 10,강 슬라브를 1100~1300℃의 온도로 재가열하는 단계; Reheating the steel slab to a temperature of 1100 to 1300 占 폚;상기 재가열된 강 슬라브를 마무리 열간압연 온도 Ar3이상의 온도로 사상압연을 마무리하는 단계; 및Finishing the reheated steel slab to a finish temperature of the finishing hot rolling temperature Ar3 or higher; And상기 열간 압연된 열연강판을 700℃ 이하의 온도로 권취하는 단계를The step of winding the hot-rolled steel sheet at a temperature of 700 ° C or less포함하는 과정에 의하여 준비되는 용융아연도금강판의 제조방법.A method of preparing a hot-dip galvanized steel sheet prepared by a process comprising the steps of:
- 제 20 항에 있어서, 상기 과정은 상기 열연강판을 산세후 냉간 압연하는 단계를 더 포함하는 용융아연도금강판의 제조방법.The method of manufacturing a hot-dip galvanized steel sheet according to claim 20, wherein the step further comprises cold picking the hot-rolled steel sheet followed by cold rolling.
- 제 10 항 내지 제 21 항 중 어느 한 항에 있어서, 소지강판이 Si, Mn 및 Al을 함량 합계로 3.5중량% 이상 포함하는 용융아연도금강판의 제조방법.22. The method for producing a hot-dip galvanized steel sheet according to any one of claims 10 to 21, wherein the base steel sheet contains Si, Mn and Al in an amount of 3.5 wt% or more in total.
- 제 22 항에 있어서, 소지강판이 Si: 0.5% 이상, Mn: 2.0% 이상, Al: 1.0% 이상 중 1종 이상을 포함하는 용융아연도금강판의 제조방법.23. The method for producing a hot-dip galvanized steel sheet according to claim 22, wherein the base steel sheet comprises at least 0.5% Si, at least 2.0% Mn and at least 1.0% Al.
- 제 23 항에 있어서, 소지강판이 중량%로, C: 0.05~0.3%, Si: 0.1~2.0%, Sol. Al: 0.005~1.5%, Mn: 1.5~8.0%, P: 0.04% 이하(0%는 제외), S: 0.015% 이하(0%는 제외), N: 0.02% 이하(0%는 제외), Cr: 1.5%이하(0% 포함), Mo: 0.2% 이하(0% 포함), Ti: 0.1% 이하(0% 포함), Sb: 0.05% 이하(0% 포함), Nb: 0.1% 이하(0% 포함), B: 0.005% 이하(0% 포함) 을 포함하는 조성을 가지는 용융아연도금강판의 제조방법.The steel sheet according to claim 23, wherein the base steel sheet contains 0.05 to 0.3% of C, 0.1 to 2.0% of Si, Al: 0.005 to 1.5%, Mn: 1.5 to 8.0%, P: not more than 0.04% (excluding 0%), S: not more than 0.015% (excluding 0%), N: not more than 0.02% Cr: not more than 1.5% (including 0%), Mo: not more than 0.2% (including 0%), Ti: not more than 0.1% (including 0%), Sb: not more than 0.05% 0%), and B: 0.005% or less (including 0%).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020170178926A KR102010076B1 (en) | 2017-12-24 | 2017-12-24 | Hot dip coated steel having good coatability and manufacturing method for the same |
| KR10-2017-0178926 | 2017-12-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2019124997A1 true WO2019124997A1 (en) | 2019-06-27 |
Family
ID=66993574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2018/016300 WO2019124997A1 (en) | 2017-12-24 | 2018-12-20 | High-strength hot-dip galvanized steel sheet having excellent coating property and method for manufacturing same |
Country Status (2)
| Country | Link |
|---|---|
| KR (1) | KR102010076B1 (en) |
| WO (1) | WO2019124997A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023244075A1 (en) * | 2022-06-17 | 2023-12-21 | 주식회사 포스코 | Steel sheet and manufacturing method therefor |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20120075260A (en) * | 2010-12-28 | 2012-07-06 | 주식회사 포스코 | Hot dip plated steel sheet excellent in plating adhesiveness and method for manufacturing the hot dip plated steel sheet |
| KR20130075499A (en) * | 2011-12-27 | 2013-07-05 | 주식회사 포스코 | Zn-coated hot rolled steel sheet having high mn and method for manufacturing the same |
| KR20130077907A (en) * | 2011-12-28 | 2013-07-09 | 주식회사 포스코 | Galvanized steel sheet having excellent surface property and coating adhesion and method for manufacturing the same |
| KR20140081616A (en) * | 2012-12-21 | 2014-07-01 | 주식회사 포스코 | Ultra-high strenth galvinized steel sheet having galvanizing property and adhesion and method for manufacturing the same |
| KR101758485B1 (en) * | 2015-12-15 | 2017-07-17 | 주식회사 포스코 | High strength hot-dip galvanized steel sheet having excellent surface quality and spot weldability, and method for manufacturing the same |
-
2017
- 2017-12-24 KR KR1020170178926A patent/KR102010076B1/en active IP Right Grant
-
2018
- 2018-12-20 WO PCT/KR2018/016300 patent/WO2019124997A1/en active Application Filing
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20120075260A (en) * | 2010-12-28 | 2012-07-06 | 주식회사 포스코 | Hot dip plated steel sheet excellent in plating adhesiveness and method for manufacturing the hot dip plated steel sheet |
| KR20130075499A (en) * | 2011-12-27 | 2013-07-05 | 주식회사 포스코 | Zn-coated hot rolled steel sheet having high mn and method for manufacturing the same |
| KR20130077907A (en) * | 2011-12-28 | 2013-07-09 | 주식회사 포스코 | Galvanized steel sheet having excellent surface property and coating adhesion and method for manufacturing the same |
| KR20140081616A (en) * | 2012-12-21 | 2014-07-01 | 주식회사 포스코 | Ultra-high strenth galvinized steel sheet having galvanizing property and adhesion and method for manufacturing the same |
| KR101758485B1 (en) * | 2015-12-15 | 2017-07-17 | 주식회사 포스코 | High strength hot-dip galvanized steel sheet having excellent surface quality and spot weldability, and method for manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| KR102010076B1 (en) | 2019-08-12 |
| KR20190077179A (en) | 2019-07-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2017105064A1 (en) | High-strength hot-dip galvanized steel sheet having excellent surface quality and spot weldability, and manufacturing method therefor | |
| WO2017111525A1 (en) | Aluminum-iron alloy-coated steel sheet for hot press forming, having excellent hydrogen delayed fracture resistance, peeling resistance, and weldability and hot-formed member using same | |
| WO2015093793A1 (en) | Plated steel sheet for hot press forming having excellent weldability and corrosion resistance, forming member, and manufacturing method thereof | |
| WO2016098964A1 (en) | High-strength cold rolled steel sheet with low material non-uniformity and excellent formability, hot dipped galvanized steel sheet, and manufacturing method therefor | |
| WO2016104880A1 (en) | Hpf molding member having excellent delamination resistance and manufacturing method therefor | |
| WO2020130631A1 (en) | High-strength galvanized steel sheet having excellent electrical resistance spot weldability, and method for producing same | |
| WO2016104879A1 (en) | Hot press-formed member with excellent powdering resistance at time of press forming, and method for manufacturing same | |
| WO2018117543A1 (en) | Hot press forming plated steel sheet having excellent impact property, hot press molding member, and manufacturing method thereof | |
| WO2017111449A1 (en) | High-strength hot-dip zinc plated steel material having excellent plating properties and method for preparing same | |
| WO2015023012A1 (en) | Ultrahigh-strength steel sheet and manufacturing method therefor | |
| WO2016104881A1 (en) | Hot press-formed (hpf) member having excellent bending characteristics and method for manufacturing same | |
| WO2016105115A1 (en) | High-strength hot-dip galvanized steel sheet having excellent surface quality, coating adhesion, and moldability, and production method therefor | |
| WO2013032173A2 (en) | High-manganese steel with superior weldability and method for manufacturing hot-dipped galvanized steel sheet from same | |
| WO2018117724A1 (en) | High strength hot rolled steel sheet and cold rolled steel sheet having excellent continuous productivity, high strength hot dip galvanized steel sheet having excellent surface quality and plating adhesion, and manufacturing method therefor | |
| WO2017111533A1 (en) | High-manganese hot-dip aluminum-coated steel sheet having excellent coating adhesion | |
| WO2018105904A1 (en) | Hot-dip galvanized steel plate with excellent bake hardenability and anti-aging property at room temperature and manufacturing method therefor | |
| WO2019124781A1 (en) | Zinc-based plated steel sheet having excellent room temperature aging resistance and bake hardenability, and method for producing same | |
| WO2019124927A1 (en) | Aluminum alloy-plated steel sheet having excellent resistance to welding liquation brittleness and excellent plating adhesion | |
| WO2019124807A1 (en) | Steel sheet with excellent bake hardening properties and corrosion resistance and method for manufacturing same | |
| WO2019124997A1 (en) | High-strength hot-dip galvanized steel sheet having excellent coating property and method for manufacturing same | |
| WO2018117770A1 (en) | Aluminum-based alloy plated steel sheet having excellent processing part corrosion resistance | |
| WO2017111428A1 (en) | High strength cold-rolled steel sheet excellent in ductility, hole-forming property and surface treatment property, molten galvanized steel sheet, and method for manufacturing same | |
| WO2013100610A1 (en) | High-manganese hot-rolled galvanized steel sheet and manufacturing method thereof | |
| WO2021125901A2 (en) | Aluminum-based alloy-plated steel sheet having excellent workability and corrosion resistance, and manufacturing method therefor | |
| WO2017018659A1 (en) | Hot-dip galvanized steel sheet and hot-dip galvannealed steel sheet with excellent shelf life and bake hardenability, and method for manufacturing same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 18890539 Country of ref document: EP Kind code of ref document: A1 |
|
| 122 | Ep: pct application non-entry in european phase |
Ref document number: 18890539 Country of ref document: EP Kind code of ref document: A1 |