TWI815504B - Cold-rolled steel plate, steel parts, manufacturing method of cold-rolled steel plate, and manufacturing method of steel parts - Google Patents
Cold-rolled steel plate, steel parts, manufacturing method of cold-rolled steel plate, and manufacturing method of steel parts Download PDFInfo
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- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 59
- 229910000831 Steel Inorganic materials 0.000 title claims description 76
- 239000010959 steel Substances 0.000 title claims description 76
- 238000004519 manufacturing process Methods 0.000 title claims description 23
- 150000001247 metal acetylides Chemical class 0.000 claims abstract description 74
- 239000002245 particle Substances 0.000 claims abstract description 46
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 26
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 23
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 21
- 239000000203 mixture Substances 0.000 claims abstract description 12
- 238000003763 carbonization Methods 0.000 claims abstract 2
- 238000000137 annealing Methods 0.000 claims description 53
- 238000010791 quenching Methods 0.000 claims description 38
- 230000000171 quenching effect Effects 0.000 claims description 38
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 36
- 238000005496 tempering Methods 0.000 claims description 35
- 238000001816 cooling Methods 0.000 claims description 33
- 238000005097 cold rolling Methods 0.000 claims description 27
- 238000000034 method Methods 0.000 claims description 24
- 238000005098 hot rolling Methods 0.000 claims description 23
- 229910052742 iron Inorganic materials 0.000 claims description 16
- 238000010438 heat treatment Methods 0.000 claims description 13
- 238000005096 rolling process Methods 0.000 claims description 10
- 238000011282 treatment Methods 0.000 claims description 7
- 238000005520 cutting process Methods 0.000 claims description 4
- 239000000835 fiber Substances 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 abstract description 7
- 230000000694 effects Effects 0.000 description 43
- 239000010955 niobium Substances 0.000 description 42
- 239000010936 titanium Substances 0.000 description 29
- 238000005516 engineering process Methods 0.000 description 16
- 230000015572 biosynthetic process Effects 0.000 description 15
- QMQXDJATSGGYDR-UHFFFAOYSA-N methylidyneiron Chemical compound [C].[Fe] QMQXDJATSGGYDR-UHFFFAOYSA-N 0.000 description 13
- 229910052761 rare earth metal Inorganic materials 0.000 description 9
- 150000002910 rare earth metals Chemical class 0.000 description 9
- 239000013078 crystal Substances 0.000 description 7
- 150000004767 nitrides Chemical class 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 239000011159 matrix material Substances 0.000 description 5
- 238000005259 measurement Methods 0.000 description 4
- 229910000677 High-carbon steel Inorganic materials 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000009863 impact test Methods 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000004753 textile Substances 0.000 description 3
- 229910001567 cementite Inorganic materials 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 238000009940 knitting Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- UNASZPQZIFZUSI-UHFFFAOYSA-N methylidyneniobium Chemical compound [Nb]#C UNASZPQZIFZUSI-UHFFFAOYSA-N 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- MTPVUVINMAGMJL-UHFFFAOYSA-N trimethyl(1,1,2,2,2-pentafluoroethyl)silane Chemical compound C[Si](C)(C)C(F)(F)C(F)(F)F MTPVUVINMAGMJL-UHFFFAOYSA-N 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Classifications
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- 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
- 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
-
- 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
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- 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- 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
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- 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
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- 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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- Organic Chemistry (AREA)
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- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Sheet Steel (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
本發明提供：韌性優異的冷軋鋼板。 本發明的冷軋鋼板，係具有：既定的組成分，存在於肥粒鐵粒內之含有Nb、Ti、V的至少其中一種元素的碳化物的平均粒徑為0.10μm以上，並且在前述碳化物中之粒徑為0.10μm以上之粒子的個數密度為100個/mm 2以上。 The present invention provides a cold-rolled steel plate excellent in toughness. The cold-rolled steel sheet of the present invention has a predetermined composition, the average particle size of carbides containing at least one element of Nb, Ti, and V present in the ferrous iron particles is 0.10 μm or more, and the carbonization is The number density of particles with a particle size of 0.10 μm or more in the object is 100 particles/mm 2 or more.
Description
本發明是關於：冷軋鋼板，尤其是關於：可以製造韌性優異的鋼製零件之冷軋鋼板。此外，本發明是關於：使用前述冷軋鋼板之鋼製零件、前述冷軋鋼板的製造方法、以及前述鋼製零件的製造方法。The present invention relates to a cold-rolled steel plate, and in particular to a cold-rolled steel plate capable of producing steel parts with excellent toughness. Furthermore, the present invention relates to steel parts using the cold-rolled steel plate, a method of manufacturing the cold-rolled steel plate, and a method of manufacturing the steel parts.
冷軋鋼板係被廣泛地使用於作為製造各種鋼製零件的素材。其中特別是由高碳鋼組成的冷軋鋼板，因為具有高硬度，因此被使用在以纖維機械用零件、軸承零件、機械用暨家庭用刀具為首之需要具有耐磨損性的用途。Cold-rolled steel sheets are widely used as raw materials for manufacturing various steel parts. Among them, cold-rolled steel sheets made of high-carbon steel are particularly used in applications requiring wear resistance, including textile machine parts, bearing parts, and machine and household knives due to their high hardness.
另一方面，纖維機械用零件、軸承零件、機械用暨家庭用刀具之類的鋼製零件，在使用時會反覆地承受到往復運動所造成的衝擊。因此，對於鋼製零件而言，為了防止往復運動的衝擊所導致的破損，還必須具有優異的韌性。On the other hand, steel parts such as textile machine parts, bearing parts, and machine and household knives are repeatedly subjected to the impact of reciprocating motion during use. Therefore, steel parts must also have excellent toughness in order to prevent damage caused by the impact of reciprocating motion.
但是，金屬材料是硬度愈高愈容易脆化，因而難以兼具有硬度與韌性。例如：一般的作法，是藉由實施淬火暨回火來提高鋼製零件的韌性，但是，實施了淬火暨回火之後，鋼材的硬度會降低，因此，只根據習知技術的淬火暨回火處理，還是無法讓硬度與韌性的兩種特性都達到高水準。However, the higher the hardness of a metal material, the more likely it is to be brittle, so it is difficult to have both hardness and toughness at the same time. For example, a common practice is to improve the toughness of steel parts by performing quenching and tempering. However, after quenching and tempering, the hardness of the steel will decrease. Therefore, only conventional quenching and tempering techniques are used. After processing, it is still impossible to achieve high levels of both hardness and toughness properties.
因此，有人就提出用來兼顧硬度與韌性的兩種特性的各種方法。Therefore, various methods for balancing the two properties of hardness and toughness have been proposed.
例如：專利文獻1、2所揭示的技術，是利用添加Nb元素所導致之結晶粒細微化的效果，來改善高碳冷軋鋼板的韌性之技術。For example, the technologies disclosed in Patent Documents 1 and 2 utilize the effect of crystal grain refinement due to the addition of Nb element to improve the toughness of high-carbon cold-rolled steel sheets.
又，專利文獻3所揭示的技術，是藉由在肥粒鐵相所組成的基質中，高密度地分散著粗大的含Nb的碳化物，來提高冷軋鋼板的耐磨損性，並且利用添加Nb元素所導致之結晶粒細微化的效果，來提高韌性之技術。Furthermore, the technology disclosed in Patent Document 3 improves the wear resistance of cold-rolled steel sheets by dispersing coarse Nb-containing carbides at a high density in a matrix composed of ferrous iron phases, and utilizes A technology that improves toughness by adding Nb element to refine the crystal grains.
專利文獻4所揭示的技術，是藉由在基質中，高密度地分散著粗大的Nb和Ti系的碳化物，並且降低孔洞的個數密度，來提昇冷軋鋼板的耐磨損性與韌性之技術。The technology disclosed in Patent Document 4 improves the wear resistance and toughness of cold-rolled steel sheets by dispersing coarse Nb and Ti-based carbides at high density in the matrix and reducing the number density of holes. technology.
專利文獻5所揭示的技術，是在對於含碳量為0.5～0.7質量%的鋼板實施最終的淬火暨回火之前，先進行退火來提高雪明碳鐵之類的碳化物的球狀化率的結果，是可以提高韌性之技術。The technology disclosed in Patent Document 5 is to anneal a steel plate with a carbon content of 0.5 to 0.7% by mass before performing final quenching and tempering to increase the spheroidization rate of carbides such as snow carbon iron. The result is technology that can improve resilience.
專利文獻6所揭示的技術，是在即將實施最終的淬火暨回火之調質處理之前的階段，先處於已經過最終退火後的狀態，藉以提昇含在素材中之生成孔洞的個數密度，因而可以生成衝孔性優異的軟質高碳鋼板之技術。The technology disclosed in Patent Document 6 is to increase the number density of generated holes contained in the material by placing it in a state that has undergone final annealing before the final quenching and tempering treatment is carried out. This enables the production of soft high-carbon steel plates with excellent punching properties.
專利文獻7所揭示的技術，是在高碳鋼鋼板中，控制不含鈮碳化物、鈦碳化物、釩碳化物之雪明碳鐵碳化物的生成，並且將雪明碳鐵碳化物的球狀化率、個數密度控制在所期望的數值，藉以提昇衝擊韌性與耐磨損性之技術。 [先前技術文獻] [專利文獻] The technology disclosed in Patent Document 7 controls the formation of snow carbon iron carbide that does not contain niobium carbide, titanium carbide, and vanadium carbide in a high carbon steel plate, and converts the snow carbon iron carbide balls into A technology that controls the transformation rate and number density to the desired values to improve impact toughness and wear resistance. [Prior technical literature] [Patent Document]
專利文獻1：日本特開平05-345952號公報 專利文獻2：日本特開2017-036492號公報 專利文獻3：日本特開2015-190036號公報 專利文獻4：日本特開2017-190494號公報 專利文獻5：日本特開2009-024233號公報 專利文獻6：日本特開2011-012316號公報 專利文獻7：日本特許第6880245號 Patent Document 1: Japanese Patent Application Publication No. 05-345952 Patent Document 2: Japanese Patent Application Publication No. 2017-036492 Patent Document 3: Japanese Patent Application Publication No. 2015-190036 Patent Document 4: Japanese Patent Application Publication No. 2017-190494 Patent Document 5: Japanese Patent Application Publication No. 2009-024233 Patent Document 6: Japanese Patent Application Publication No. 2011-012316 Patent Document 7: Japanese Patent No. 6880245
[發明所欲解決的問題][Problem to be solved by the invention]
專利文獻1、2所揭示的技術，是利用添加Nb元素所導致之結晶粒細微化的效果，來提昇高碳冷軋鋼板的韌性。但是，添加Nb元素所導致之結晶粒細微化的效果，當Nb的含量在0.1質量%的程度時就已經飽和，因此，只依賴結晶粒微細化的效果還是無法得到所需的韌性。The technology disclosed in Patent Documents 1 and 2 improves the toughness of high-carbon cold-rolled steel sheets by utilizing the effect of crystal grain refinement caused by the addition of Nb element. However, the effect of refining the crystal grains due to the addition of Nb element is saturated when the Nb content is around 0.1% by mass. Therefore, it is still impossible to obtain the required toughness only by relying on the effect of refining the crystal grains.
又，專利文獻3所揭示的技術中，也是利用添加Nb元素所導致之結晶粒細微化的效果來提昇韌性。但是，專利文獻3的技術，是為了提昇耐磨損性而利用了含Nb的碳化物，然而，含Nb的碳化物卻是導致降低韌性的主要原因。因此，將會導致添加Nb所獲得的效果與含Nb的碳化物所獲得的效果互相抵消，而無法獲得所需的韌性。In addition, the technology disclosed in Patent Document 3 also utilizes the effect of refining crystal grains due to the addition of Nb element to improve toughness. However, the technology of Patent Document 3 utilizes Nb-containing carbides in order to improve wear resistance. However, Nb-containing carbides are the main cause of reduced toughness. Therefore, the effect obtained by adding Nb and the effect obtained by Nb-containing carbide will cancel each other out, and the required toughness cannot be obtained.
與專利文獻3同樣地，專利文獻4所揭示的技術中，是利用將硬質的Nb和Ti系的碳化物高密度地分散於基質中來提昇耐磨損性的效果。但是，將Nb和Ti系的碳化物高密度地分散於基質中的情況下，在實施冷軋時，會在基質與碳化物之間產生孔洞，其結果會導致韌性降低。因此，專利文獻4的技術，必須藉由限制冷軋時的軋縮率來抑制孔洞的產生。但是，因為這種方法的軋縮率受到限制的緣故，能夠製造之冷軋鋼板的板厚度和機械特性也必然受到限制，無法被稱為根本性的解決方案。Like Patent Document 3, the technology disclosed in Patent Document 4 utilizes the effect of dispersing hard Nb and Ti-based carbides in a matrix at high density to improve wear resistance. However, when Nb and Ti-based carbides are dispersed in a matrix at a high density, holes may be generated between the matrix and the carbides during cold rolling, resulting in reduced toughness. Therefore, the technology of Patent Document 4 must suppress the generation of holes by limiting the reduction ratio during cold rolling. However, because the reduction rate of this method is limited, the thickness and mechanical properties of the cold-rolled steel sheets that can be produced are also inevitably limited, and it cannot be called a fundamental solution.
又，專利文獻5～7所揭示的技術中，韌性依舊還是不夠充分。Furthermore, the technologies disclosed in Patent Documents 5 to 7 still have insufficient toughness.
本發明是有鑑於上述的情事而進行開發完成的，其目的是要針對於：使用Nb等的碳化物來提昇硬度的冷軋鋼板，實現更為優異的韌性。 [解決問題之技術手段] The present invention was developed in view of the above-mentioned circumstances, and its purpose is to achieve more excellent toughness in cold-rolled steel sheets using carbides such as Nb to increase hardness. [Technical means to solve problems]
本發明人等，針對於用來解決上述技術課題的方法進行檢討之後的結果，獲得了下列的兩種創見。As a result of examining methods for solving the above technical problems, the present inventors obtained the following two original ideas.
(1)藉由適當地控制冷軋鋼板中之Nb、Ti、V系的碳化物的大小與密度，可以有效地提昇對於該冷軋鋼板實施淬火暨回火之後的韌性。其結果，就可以製造出硬度與韌性都達到高水準之鋼製零件。(1) By appropriately controlling the size and density of Nb, Ti, and V-based carbides in cold-rolled steel sheets, the toughness of the cold-rolled steel sheets after quenching and tempering can be effectively improved. As a result, steel parts with high levels of hardness and toughness can be produced.
(2)藉由適當地控制所使用之鋼胚料的組成分以及冷軋鋼板的製造條件，就可以適當地控制冷軋鋼板中之Nb、Ti、V系的碳化物的大小與密度。(2) By appropriately controlling the composition of the steel blank used and the manufacturing conditions of the cold-rolled steel plate, the size and density of Nb, Ti, and V-based carbides in the cold-rolled steel plate can be appropriately controlled.
本發明是依據上述的創見而開發完成的，其要旨係如下所述。The present invention was developed based on the above-mentioned original idea, and its gist is as follows.
1.一種冷軋鋼板，其組成分，以質量%計，係含有 C：0.6～1.25%、 Si：0.10～0.55%、 Mn：0.20～2.0%、 P：0.0005～0.05%、 S：0.03%以下、 Al：0.001～0.1%、 N：0.001～0.009%、 Cr：0.1～1.0%、以及 從Ti：0.01～1.0%、Nb：0.05～0.5%及V：0.01～1.0%之中選出的一種或兩種以上， 其餘的組成分是Fe以及不可避免的雜質， 存在於肥粒鐵粒內之含有Nb、Ti、V的至少其中一種元素之碳化物的平均粒徑為0.10μm以上，而且 在前述碳化物中之粒徑為0.10μm以上之粒子的個數密度為100個/mm 2以上。 1. A cold-rolled steel plate whose composition, in mass %, contains C: 0.6~1.25%, Si: 0.10~0.55%, Mn: 0.20~2.0%, P: 0.0005~0.05%, S: 0.03% The following: Al: 0.001 to 0.1%, N: 0.001 to 0.009%, Cr: 0.1 to 1.0%, and one selected from Ti: 0.01 to 1.0%, Nb: 0.05 to 0.5%, and V: 0.01 to 1.0% or two or more, the remaining components are Fe and inevitable impurities. The average particle size of carbides containing at least one element of Nb, Ti, and V present in the fat iron particles is 0.10 μm or more, and the The number density of particles having a particle diameter of 0.10 μm or more in the carbide is 100 particles/mm 2 or more.
2.如上述1所述之冷軋鋼板，前述組成分，以質量%計，還含有：從 Sb：0.1%以下、 Hf：0.5%以下、 REM：0.1%以下、 Cu：0.5%以下、 Ni：3.0%以下、 Sn：0.5%以下、 Mo：1%以下、 Zr：0.5%以下、 B：0.005%以下、以及 W：0.01%以下所組成的群中選出的一種或兩種以上。 2. The cold-rolled steel plate as described in 1 above, the aforementioned components, in mass %, also include: Sb: 0.1% or less, Hf: 0.5% or less, REM: 0.1% or less, Cu: 0.5% or less, Ni: 3.0% or less, Sn: 0.5% or less, Mo: less than 1%, Zr: 0.5% or less, B: 0.005% or less, and W: One or two or more types selected from a group consisting of less than 0.01%.
3.一種鋼製零件，係對於如上述1或2所述之冷軋鋼板實施淬火暨回火處理而製成的。3. A steel part produced by subjecting the cold-rolled steel plate as described in 1 or 2 above to quenching and tempering.
4.如上述3所述之鋼製零件，前述鋼製零件是：纖維機械用零件、軸承零件以及刀具之任一種。4. The steel parts as described in 3 above, which are any of fiber machinery parts, bearing parts, and cutting tools.
5.一種冷軋鋼板的製造方法，係將具有上述1或2所述之組成分的鋼胚料加熱； 將被加熱後之前述鋼胚料，以精軋開始溫度為Ac3點以上的條件，進行熱軋而成為熱軋鋼板； 將前述熱軋鋼板，以從前述熱軋結束起迄冷卻開始的時間為2秒以下、平均冷卻速度為25℃/秒以上、冷卻停止溫度為720℃以下的條件，進行冷卻； 將冷卻後的前述熱軋鋼板進行捲取； 對於前述捲取後的熱軋鋼板，實施：退火溫度為650℃以上且780℃以下、退火時間為3小時以上的條件之第1次退火； 對於前述第1次退火後的熱軋鋼板，反覆地實施兩次以上之軋縮率為15%以上的冷軋以及退火溫度為600～800℃的第2次退火，然後，再實施軋縮率為20%以上的最終冷軋。 5. A method for manufacturing cold-rolled steel plates, which involves heating steel blanks having the composition described in 1 or 2 above; The aforementioned steel blank after being heated is hot-rolled under the condition that the finishing rolling start temperature is Ac3 point or above to become a hot-rolled steel plate; The hot-rolled steel sheet is cooled under conditions such that the time from the end of the hot rolling to the start of cooling is 2 seconds or less, the average cooling rate is 25°C/second or more, and the cooling stop temperature is 720°C or less; Coil the cooled hot-rolled steel plate; For the above-mentioned coiled hot-rolled steel sheet, perform the first annealing under the conditions of an annealing temperature of 650°C or more and 780°C or less, and an annealing time of 3 hours or more; For the hot-rolled steel sheet after the first annealing, cold rolling with a reduction rate of 15% or more and a second annealing with an annealing temperature of 600 to 800°C are repeatedly performed two or more times, and then the reduction rate is performed again. For more than 20% final cold rolling.
6.如上述5所述之冷軋鋼板的製造方法，其中，前述第2次退火的昇溫速度是50℃/小時以上。6. The method for manufacturing a cold-rolled steel sheet according to 5 above, wherein the temperature rise rate of the second annealing is 50° C./hour or more.
7.一種鋼製零件的製造方法，係將以上述5或上述6所述之製造方法來製造的冷軋鋼板，先以淬火溫度為700℃以上且800℃以下、保持時間為1分鐘以上且少於60分鐘的條件來實施淬火；接下來，以回火溫度為為150～300℃、保持時間為20分鐘以上且3小時以下的條件來實施回火。 [發明之效果] 7. A method of manufacturing steel parts, which is a cold-rolled steel plate manufactured by the manufacturing method described in the above 5 or the above 6, first with a quenching temperature of 700°C or more and 800°C or less, and a holding time of 1 minute or more and Quenching is performed under conditions of less than 60 minutes; next, tempering is performed under conditions such that the tempering temperature is 150 to 300°C and the holding time is 20 minutes or more and 3 hours or less. [Effects of the invention]
根據本發明，係可在使用Nb等的碳化物來提昇硬度之冷軋鋼板中，獲得更優異之淬火暨回火後的韌性。因此，本發明的冷軋鋼板可以極適用於作為以纖維機械用零件、軸承零件以及機械用暨家庭用的刀具為首的各種鋼製零件的素材。因此，根據本發明，係可提供使用前述冷軋鋼板之鋼製零件。According to the present invention, more excellent toughness after quenching and tempering can be obtained in a cold-rolled steel sheet using carbides such as Nb to increase hardness. Therefore, the cold-rolled steel sheet of the present invention is extremely suitable as a material for various steel parts including fiber machine parts, bearing parts, and machine and household knives. Therefore, according to the present invention, it is possible to provide steel parts using the aforementioned cold-rolled steel sheet.
以下將詳細說明本發明。此外，本發明並不限定於這種實施方式。又，本發明是著眼於：存在於肥粒鐵粒內之含有Nb、Ti、V的至少其中一種元素的碳化物。因此，在以下的說明中，有時候也會將「存在於肥粒鐵粒內之含有Nb、Ti、V的至少其中一種元素的碳化物」予以簡稱為「碳化物」。The present invention will be described in detail below. In addition, the present invention is not limited to this embodiment. Furthermore, the present invention focuses on carbides containing at least one element of Nb, Ti, and V present in ferrous iron particles. Therefore, in the following description, "carbide containing at least one element of Nb, Ti, and V existing in ferrous iron particles" is sometimes referred to as "carbide".
[組成分] 本發明的冷軋鋼板是具有上述的組成分。以下，將說明限定其含量之理由。此外，在以下的說明中，作為含量的單位之「%」，如果沒有做特別聲明的話，都是指：「質量%」。 [components] The cold-rolled steel plate of the present invention has the above-mentioned composition. The reasons for limiting the content will be explained below. In addition, in the following description, "%" as the unit of content refers to "mass %" unless otherwise stated.
C：0.6～1.25% C是用來提昇在淬火暨回火之後的硬度所需的元素。此外，C也是用來生成雪明碳鐵、以及與Nb、Ti、V等的元素之碳化物所需的元素。為了生成所需量的碳化物來獲得淬火暨回火之後的強度，必須將C含量設定在0.6%以上。因此，將C含量設定在0.6%以上，更好是在0.7%以上。另一方面，C含量超過1.25%的話，硬度將會過度上昇而導致脆化。又，C含量超過1.25%的話，加熱時的表面鏽皮將會變堅硬，其結果會導致表面性狀惡化。因此，將C含量設定在1.25%以下，更好是在1.20%以下。 C: 0.6～1.25% C is an element required to increase the hardness after quenching and tempering. In addition, C is also an element required to generate carbides with snow carbon iron and elements such as Nb, Ti, and V. In order to generate the required amount of carbides to obtain strength after quenching and tempering, the C content must be set above 0.6%. Therefore, the C content is set to 0.6% or more, preferably 0.7% or more. On the other hand, if the C content exceeds 1.25%, the hardness will increase excessively and lead to embrittlement. In addition, if the C content exceeds 1.25%, the surface scale will harden during heating, resulting in deterioration of surface properties. Therefore, the C content is set to 1.25% or less, preferably 1.20% or less.
Si：0.10～0.55% Si是具有可藉由固溶強化來提高強度的效果之元素。為了獲得前述效果，乃將Si含量設定在0.10%以上，更好是在0.12%以上，更優是在0.14%以上。另一方面，Si含量太多的話，將會生成Si氧化物而導致韌性降低。另一方面，Si含量太多的話，將會促進肥粒鐵的生成以及粒子成長而促進該粒子析出在碳化物的粒界，因而抑制了碳化物析出於肥粒鐵粒內。此外，Si含量太多的話，在進行加熱時，表面鐵鏽會變得堅硬，其結果將會導致表面性狀惡化。因此，將Si含量設定在0.55%以下，更好是在0.50%以下，更優是在0.45%以下。 Si: 0.10～0.55% Si is an element that has the effect of improving strength through solid solution strengthening. In order to obtain the aforementioned effects, the Si content is set to 0.10% or more, preferably 0.12% or more, and more preferably 0.14% or more. On the other hand, if the Si content is too high, Si oxide will be formed, resulting in a decrease in toughness. On the other hand, if the Si content is too high, the formation and particle growth of fat iron will be promoted and the particles will be precipitated at the grain boundaries of carbides, thereby inhibiting the precipitation of carbides in the fat iron particles. In addition, if the Si content is too high, surface rust will harden when heated, resulting in deterioration of surface properties. Therefore, the Si content is set to 0.55% or less, more preferably 0.50% or less, more preferably 0.45% or less.
Mn：0.20～2.0% Mn是可藉由促進淬火並且抑制回火軟化而具有提昇硬度的作用之元素。為了抑制回火軟化，必須抑制C生成為雪明碳鐵，或者是延遲差排恢復原狀，Mn是兼具有這兩種作用，藉由添加Mn，可以在實施回火之後，還維持在高差排密度之高硬度組織。為了獲得前述效果，乃將Mn含量設定在0.20%以上，更好是在0.25%以上。另一方面，Mn含量超過2.0%的話，Mn將會偏析出來而生成帶狀的組織。尤其是在MnS的偏析部位，很容易發生異常的晶粒成長、以及組織的不均質現象，因為在肥粒鐵粒界產生了局部性的析出，因而抑制了在肥粒鐵粒內之碳化物的生成。並且也會成為在進行加工時之發生裂痕和形狀不良的原因。因此，乃將Mn含量設定在2.0%以下，更好是在1.95%以下。 Mn: 0.20～2.0% Mn is an element that has the effect of increasing hardness by promoting quenching and inhibiting temper softening. In order to suppress tempering softening, it is necessary to suppress the formation of C into snow carbon iron or the delayed dislocation from returning to its original state. Mn has both of these effects. By adding Mn, it can be maintained at a high level after tempering. High hardness structure with differential density. In order to obtain the aforementioned effects, the Mn content is set to 0.20% or more, preferably 0.25% or more. On the other hand, if the Mn content exceeds 2.0%, Mn will segregate and form a band-like structure. Especially in the segregation parts of MnS, abnormal grain growth and structural inhomogeneity are easy to occur because local precipitation occurs at the boundaries of the fat iron grains, thereby suppressing the carbide in the fat iron grains. of generation. It may also cause cracks and poor shape during processing. Therefore, the Mn content is set to 2.0% or less, preferably 1.95% or less.
P：0.0005～0.05% 只要微量添加P，即可利用固溶強化來獲得提昇強度的效果。為了獲得前述效果，乃將P含量設定在0.0005%以上，更好是在0.0008%以上。另一方面，P含量超過0.05%的話，將會因為粒界脆化而導致韌性降低。因此，將P含量設定在0.05%以下，更好是在0.045%以下。 P: 0.0005～0.05% As long as a trace amount of P is added, solid solution strengthening can be used to achieve the effect of increasing strength. In order to obtain the aforementioned effects, the P content is set to 0.0005% or more, preferably 0.0008% or more. On the other hand, if the P content exceeds 0.05%, the toughness will decrease due to grain boundary embrittlement. Therefore, the P content is set to 0.05% or less, preferably 0.045% or less.
S：0.03%以下 S是與Mn一起形成硫化物而導致韌性降低。因此，乃將S含量設定在0.03%以下，更好是在0.02%以下。另一方面，基於提昇韌性的觀點考量，S含量是愈低愈好，因此，S含量的下限並未特別限定，也可以是0%。但是，過度地減少S含量的話，將會導致製造成本的增加，所以基於工業性規模的生産之觀點考量，係將S含量設定在0.0005%以上為宜，設定在0.001%以上更好。 S: 0.03% or less S forms sulfide together with Mn, resulting in reduced toughness. Therefore, the S content is set to 0.03% or less, preferably 0.02% or less. On the other hand, from the perspective of improving toughness, the lower the S content, the better. Therefore, the lower limit of the S content is not particularly limited and may also be 0%. However, excessively reducing the S content will lead to an increase in manufacturing costs. Therefore, from the perspective of industrial-scale production, it is appropriate to set the S content to 0.0005% or more, and even better to set it to 0.001% or more.
Al：0.001～0.1% Al是在進行製鋼時之用來脱氧所需的元素。因此，乃將Al含量設定在0.001%以上。另一方面，Al含量過多的話，將會形成氮化物，而會促進以這種氮化物為起點之裂痕或孔洞的形成，其結果將會導致韌性降低。因此，乃將Al含量設定在0.1%以下，更好是在0.08%以下，更優是在0.06%以下。 Al: 0.001～0.1% Al is an element required for deoxidation during steelmaking. Therefore, the Al content is set above 0.001%. On the other hand, if the Al content is too high, nitrides will be formed, which will promote the formation of cracks or holes starting from these nitrides, resulting in a decrease in toughness. Therefore, the Al content is set to 0.1% or less, preferably 0.08% or less, more preferably 0.06% or less.
N：0.001～0.009% N係可藉由形成細微的氮化物而使得粒徑微細化因而可以提昇韌性之元素。因此，乃將N含量設定在0.001%以上。另一方面，N含量過多的話，將會與Al結合而形成氮化物，而會促進以這種氮化物為起點之裂痕或孔洞的形成，其結果將會導致韌性降低。因此，乃將N含量設定在0.009%以下，更好是在0.008%以下。 N：0.001～0.009% N is an element that can refine the particle size by forming fine nitrides, thereby improving toughness. Therefore, the N content is set above 0.001%. On the other hand, if the N content is too high, it will combine with Al to form nitride, which will promote the formation of cracks or holes starting from this nitride, resulting in a decrease in toughness. Therefore, the N content is set to 0.009% or less, preferably 0.008% or less.
Cr：0.1～1.0% Cr是具有可提高鋼的淬火性而可提昇強度之元素。為了獲得前述效果，乃將Cr含量設定在0.1%以上，更好是在0.12%以上。另一方面，Cr含量太多的話，將會形成粗大的Cr碳化物以及Cr氮化物，並且在前述Cr碳化物以及Cr氮化物的周圍產生了孔洞，其結果將會導致韌性降低。因此，乃將Cr含量設定在1.0%以下，更好是在0.95%以下。 Cr: 0.1～1.0% Cr is an element that can improve the hardenability of steel and increase its strength. In order to obtain the aforementioned effects, the Cr content is set to 0.1% or more, preferably 0.12% or more. On the other hand, if the Cr content is too high, coarse Cr carbides and Cr nitrides will be formed, and holes will be generated around the Cr carbides and Cr nitrides, resulting in a decrease in toughness. Therefore, the Cr content is set to 1.0% or less, preferably 0.95% or less.
上述組成分還含有從Ti：0.01～1.0%、Nb：0.05～0.5%以及V：0.01～1.0%之中所選出的一種或兩種以上。為了獲得所期望之碳化物的個數密度，必須將Ti、Nb以及V中的至少一種元素，依照上述的含量來進行添加。The above-mentioned composition further contains one or two or more types selected from Ti: 0.01 to 1.0%, Nb: 0.05 to 0.5%, and V: 0.01 to 1.0%. In order to obtain the desired number density of carbides, at least one element among Ti, Nb and V must be added according to the above-mentioned content.
Ti：0.01～1.0% Ti是具有可在肥粒鐵粒內形成碳化物來提昇韌性的效果之元素。如果想要添加Ti的話，為了獲得前述效果，必須將Ti含量設定在0.01%以上，更好是在0.015%以上。另一方面，Ti含量太多的話，沃斯田鐵化溫度將會變高，因此，熱軋時的溫度會降低而導致很容易在鋼板的表面生成肥粒鐵。生成在表面的肥粒鐵，在經過後續的冷軋以及退火之後依舊會殘留下來，而優先地讓碳化物生成在肥粒鐵粒界，其結果將會抑制碳化物生成在粒內。因此，乃將Ti含量設定在1.0%以下，更好是在0.9%以下。 Ti: 0.01～1.0% Ti is an element that has the effect of forming carbides in ferrous iron particles to improve toughness. If you want to add Ti, in order to obtain the aforementioned effects, the Ti content must be set to 0.01% or more, preferably 0.015% or more. On the other hand, if the Ti content is too high, the Vostian ironization temperature will increase, so the temperature during hot rolling will decrease and fat particles will easily form on the surface of the steel plate. The fat iron formed on the surface will still remain after subsequent cold rolling and annealing, and carbides are preferentially formed at the boundaries of the fat iron grains, which will inhibit the formation of carbides within the grains. Therefore, the Ti content is set to 1.0% or less, preferably 0.9% or less.
Nb：0.05～0.5% Nb是可將碳化物形成在肥粒鐵粒內，是具有提高韌性的效果之元素。此外，Nb也是具有使結晶粒變細微化的效果很大的元素。如果想要添加Nb的話，為了獲得前述效果，必須將Nb含量設定在0.05%以上。另一方面，Nb含量太多的話，將會在粒界生成碳化物，並且生成在粒內之碳化物的個數密度將會減少。生成在粒界的碳化物將會成為發生孔洞或裂痕之起點，所以韌性會降低。因此，乃將Nb含量設定在0.5%以下，更好是在0.45%以下。 Nb: 0.05～0.5% Nb is an element that can form carbides in ferrous iron particles and has the effect of improving toughness. In addition, Nb is also an element that has a great effect of miniaturizing crystal grains. If you want to add Nb, in order to obtain the aforementioned effects, the Nb content must be set to 0.05% or more. On the other hand, if the Nb content is too high, carbides will be formed at the grain boundaries, and the number density of carbides formed within the grains will be reduced. Carbides generated at grain boundaries will become the starting point for holes or cracks, so the toughness will be reduced. Therefore, the Nb content is set to 0.5% or less, preferably 0.45% or less.
V：0.01～1.0% V是可將碳化物形成在肥粒鐵粒內，是具有提高韌性的效果之元素。此外，V也具有提高淬火性的效果，可以提昇鋼的強度。又，為了抑制回火軟化，必須抑制C生成為雪明碳鐵，或者是延遲差排恢復原狀，V是兼具有這兩種作用，藉由添加V，可以在實施回火之後，還維持著加工組織而可提昇韌性。為了獲得前述效果，乃將V含量設定在0.01%以上。另一方面，V含量太多的話，生成在粒界的碳化物將會粗大化，而生成在粒界的碳化物將會成為發生孔洞或裂痕之起點，所以韌性會降低。因此，乃將V含量設定在1.0%以下，更好是在0.95%以下。 V: 0.01～1.0% V is an element that can form carbides in ferrous iron particles and has the effect of improving toughness. In addition, V also has the effect of improving hardenability and can increase the strength of steel. In addition, in order to suppress tempering softening, it is necessary to suppress the formation of C into crystalline carbon iron, or to delay the dislocation from returning to its original state. V has both of these effects. By adding V, it can be maintained even after tempering. It can improve toughness by processing the structure. In order to obtain the aforementioned effects, the V content is set above 0.01%. On the other hand, if the V content is too high, the carbides formed at the grain boundaries will become coarse, and the carbides formed at the grain boundaries will become the starting point for holes or cracks, so the toughness will be reduced. Therefore, the V content is set to 1.0% or less, preferably 0.95% or less.
本發明的其中一種實施方式的冷軋鋼板的組成分是具有以上的成分之外，其餘的組成分是Fe以及不可避免的雜質。The cold-rolled steel sheet according to one embodiment of the present invention has the above components, and the remaining components are Fe and inevitable impurities.
此外，在本發明的其他實施方式中，上述組成分中還可以含有從Sb：0.1%以下、Hf：0.5%以下、REM：0.1%以下、Cu：0.5%以下、Ni：3.0%以下、Sn：0.5%以下、Mo：1%以下、Zr：0.5%以下、B：0.005%以下、以及W：0.01%以下所組成的群中隨意地選出的一種或兩種以上。In addition, in other embodiments of the present invention, the above-mentioned components may also contain Sb: 0.1% or less, Hf: 0.5% or less, REM: 0.1% or less, Cu: 0.5% or less, Ni: 3.0% or less, Sn : 0.5% or less, Mo: 1% or less, Zr: 0.5% or less, B: 0.005% or less, and W: 0.01% or less, one or two or more randomly selected from the group.
Sb：0.1%以下 Sb雖然是對於提昇耐腐蝕性很有效的元素，但是過度添加的話，將會在熱軋時所生成的鏽皮下方生成富Sb層，而在熱軋後導致鋼板發生表面鱗片狀剝離(剝離痕)。因此，乃將Sb含量設定在0.1%以下。另一方面，Sb含量的下限，雖然並未特別限定，但是基於提高添加效果的觀點考量，將Sb含量設定在0.0003%以上為宜。 Sb: 0.1% or less Although Sb is an element that is very effective in improving corrosion resistance, if it is excessively added, an Sb-rich layer will be formed under the scale generated during hot rolling, which will cause scaly peeling (peeling marks) on the surface of the steel plate after hot rolling. ). Therefore, the Sb content is set below 0.1%. On the other hand, although the lower limit of the Sb content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Sb content to 0.0003% or more.
Hf：0.5%以下 Hf雖然是對於提昇耐腐蝕性很有效的元素，但是過度添加的話，將會在熱軋時所生成的鏽皮下方生成富Hf層，而在熱軋後導致鋼板發生表面鱗片狀剝離(剝離痕)。因此，乃將Hf含量設定在0.5%以下。另一方面，Hf含量的下限，雖然並未特別限定，但是基於提高添加效果的觀點考量，將Hf含量設定在0.001%以上為宜。 Hf: 0.5% or less Although Hf is an element that is very effective in improving corrosion resistance, if it is excessively added, an Hf-rich layer will be formed under the scale generated during hot rolling, which will cause scaly peeling (peeling marks) on the surface of the steel plate after hot rolling. ). Therefore, the Hf content is set below 0.5%. On the other hand, although the lower limit of the Hf content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Hf content to 0.001% or more.
REM：0.1%以下 REM(稀土金屬)是用來提昇鋼的強度之元素。但是，過度添加REM的話，將會延緩雪明碳鐵的球狀化，在進行冷間加工時，將會助長不均質的變形而導致表面性狀惡化。因此，將REM含量設定在0.1%以下。另一方面，REM含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將REM含量設定在0.005%以上為宜。 REM: 0.1% or less REM (Rare Earth Metal) is an element used to increase the strength of steel. However, excessive addition of REM will delay the spheroidization of snow carbon iron and promote heterogeneous deformation during cold working, resulting in deterioration of surface properties. Therefore, the REM content is set to 0.1% or less. On the other hand, although the lower limit of the REM content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the REM content to 0.005% or more.
Cu：0.5%以下 Cu雖然是對於提昇耐腐蝕性很有效的元素，但是過度添加的話，將會在熱軋時所生成的鏽皮下方生成富Cu層，而在熱軋後導致鋼板發生表面鱗片狀剝離(剝離痕)。因此，乃將Cu添加量設定在0.5%以下。另一方面，Cu含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將Cu含量設定在0.01%以上為宜。 Cu: 0.5% or less Although Cu is an element that is very effective in improving corrosion resistance, if it is excessively added, a Cu-rich layer will be formed under the scale generated during hot rolling, which will cause scaly peeling (peeling marks) on the surface of the steel plate after hot rolling. ). Therefore, the Cu addition amount is set below 0.5%. On the other hand, although the lower limit of the Cu content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Cu content to 0.01% or more.
Ni：3.0%以下 Ni是用來提昇鋼的強度之元素。但是，過度添加Ni的話，在進行冷間加工時，將會助長不均質的變形而導致表面性狀惡化。因此，將Ni含量設定在3.0%以下。另一方面，Ni含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將Ni含量設定在0.01%以上為宜。 Ni: 3.0% or less Ni is an element used to increase the strength of steel. However, excessive addition of Ni will promote non-uniform deformation during cold processing, resulting in deterioration of surface properties. Therefore, the Ni content is set to 3.0% or less. On the other hand, although the lower limit of the Ni content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Ni content to 0.01% or more.
Sn：0.5%以下 Sn雖然是對於提昇耐腐蝕性很有效的元素，但是過度添加的話，將會在熱軋時所生成的鏽皮下方生成富Sn層，而在熱軋後導致鋼板發生表面鱗片狀剝離(剝離痕)。因此，乃將Sn含量設定在0.5%以下。另一方面，Sn含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將Sn含量設定在0.0001%以上為宜。 Sn: 0.5% or less Although Sn is an element that is very effective in improving corrosion resistance, if it is excessively added, a Sn-rich layer will be formed under the scale generated during hot rolling, which will cause scaly peeling (peeling marks) on the surface of the steel plate after hot rolling. ). Therefore, the Sn content is set below 0.5%. On the other hand, although the lower limit of the Sn content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Sn content to 0.0001% or more.
Mo：1%以下 Mo是用來提昇鋼的強度之元素。但是，過度添加的話，將會延緩雪明碳鐵的球狀化，在進行冷間加工時會助長不均質的變形而導致表面性狀惡化。因此，乃將Mo含量設定在1%以下。另一方面，Mo含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將Mo含量設定在0.001%以上為宜。 Mo: less than 1% Mo is an element used to increase the strength of steel. However, excessive addition will delay the spheroidization of snow carbon iron and promote heterogeneous deformation during cold working, resulting in deterioration of surface properties. Therefore, the Mo content is set to 1% or less. On the other hand, although the lower limit of the Mo content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Mo content to 0.001% or more.
Zr：0.5%以下 Zr雖然是對於提昇耐腐蝕性很有效的元素，但是過度添加的話，將會在熱軋時所生成的鏽皮下方生成富Zr層，而在熱軋後導致鋼板發生表面鱗片狀剝離(剝離痕)。因此，乃將Zr含量設定在0.5%以下。另一方面，Zr含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，將Zr含量設定在0.01%以上為宜。 Zr: 0.5% or less Although Zr is an element that is very effective in improving corrosion resistance, if it is excessively added, a Zr-rich layer will be formed under the scale generated during hot rolling, which will cause scaly peeling (peeling marks) on the surface of the steel plate after hot rolling. ). Therefore, the Zr content is set below 0.5%. On the other hand, although the lower limit of the Zr content is not particularly limited, from the viewpoint of improving the addition effect, it is appropriate to set the Zr content to 0.01% or more.
B：0.005%以下 B是具有提昇淬火性的作用之元素，可以配合需求進行添加。但是，B含量超過0.005%的話，在進行淬火時，很容易在表面發生裂痕。因此，乃將B含量設定在0.005%以下。另一方面，B含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，想要添加B的情況下，係將B含量設定在0.0001%以上為宜。 B: 0.005% or less B is an element that has the function of improving hardenability and can be added according to needs. However, if the B content exceeds 0.005%, cracks will easily occur on the surface during quenching. Therefore, the B content is set below 0.005%. On the other hand, although the lower limit of the B content is not particularly limited, from the viewpoint of improving the addition effect, when it is desired to add B, it is appropriate to set the B content to 0.0001% or more.
W：0.01%以下 W是具有提昇淬火性的作用之元素，可以配合需求進行添加。但是，W含量超過0.01%的話，在進行淬火時，很容易在表面發生裂痕。因此，乃將W含量設定在0.01%以下。另一方面，W含量的下限雖然並未特別限定，但是基於提高添加效果的觀點考量，想要添加W的情況下，係將W含量設定在0.001%以上為宜。 W: 0.01% or less W is an element that has the function of improving hardenability and can be added according to needs. However, if the W content exceeds 0.01%, cracks will easily occur on the surface during quenching. Therefore, the W content is set below 0.01%. On the other hand, although the lower limit of the W content is not particularly limited, from the viewpoint of improving the addition effect, when adding W, it is appropriate to set the W content to 0.001% or more.
[碳化物] 其次，說明含在本發明的冷軋鋼板中的碳化物。 [carbide] Next, the carbides contained in the cold-rolled steel sheet of the present invention will be described.
平均粒徑為0.10μm以上 個數密度為100個/mm 2以上 在開始進行零件加工的前置工序中的冷軋前的階段，預先製作成已經在肥粒鐵粒內生成了Ti、Nb、V系的碳化物之組織，然後，經過實施冷軋時所生成的加工組織之後，又實施了淬火暨回火處理的話，一部分細微的Ti、Nb、V系的碳化物將會再析出在亞粒界。利用這種組織，能夠增加可對抗因為反覆變形而被導入的應變之阻力，而可提昇最終製品的韌性。為了要獲得這種效果，必須將存在於肥粒鐵粒內之含有Ti、Nb、V之至少其中一種元素的碳化物之平均粒徑設定為0.10μm以上。基於同樣的理由，必須將前述碳化物中之平均粒徑為0.10μm以上的碳化物的個數密度設定為100個/mm 2以上。 The average particle size is 0.10 μm or more and the number density is 100 particles/mm 2 or more. In the pre-processing step before starting the part processing, Ti, Nb, and The structure of V-based carbides, and then after the processed structure generated during cold rolling, is quenched and tempered, some fine Ti, Nb, and V-based carbides will be precipitated again in the sub-surface. Grain boundary. Using this structure can increase the resistance against the strains introduced due to repeated deformation, thereby improving the toughness of the final product. In order to obtain this effect, the average particle diameter of the carbide containing at least one element of Ti, Nb, and V present in the fat iron particles must be set to 0.10 μm or more. For the same reason, the number density of carbides with an average particle diameter of 0.10 μm or more among the aforementioned carbides must be set to 100/mm 2 or more.
如果碳化物的平均粒徑小於0.10μm的話，在淬火暨回火處理之後所析出之細微的Ti、Nb、V系的碳化物之數量不足，無法獲得可提高韌性的效果。此外，如果碳化物的個數密度少於100個/mm 2的話，也是與平均粒徑的情況同樣地，在淬火暨回火處理之後所析出之細微的Ti、Nb、V系的碳化物之數量不足，無法獲得可提高韌性的效果。 If the average particle size of the carbides is less than 0.10 μm, the amount of fine Ti, Nb, and V-based carbides precipitated after the quenching and tempering treatment is insufficient, and the effect of improving toughness cannot be obtained. In addition, if the number density of carbides is less than 100/ mm2 , the same as the case of the average particle size, among the fine Ti, Nb, and V-based carbides precipitated after the quenching and tempering treatment. Insufficient quantities to obtain the toughness-increasing effect.
[板厚度] 前述冷軋鋼板的板厚度，雖然並未特別限定，可以是隨意的厚度，但是以設定在0.1mm以上為宜，設定在0.2mm以上更好。又，板厚度的上限雖然也並未特別限定，但是以設定在2.5mm以下為宜，設定在1.6mm以下更好，設定在0.8mm以下更優。如果板厚度落在0.2mm以上且0.8mm以下的話，可以很適合用來作為針織機用針之類的纖維機械零件用的素材。 [Board thickness] Although the thickness of the cold-rolled steel sheet is not particularly limited and may be any thickness, it is preferably set to 0.1 mm or more, and more preferably 0.2 mm or more. In addition, the upper limit of the plate thickness is not particularly limited, but it is preferably set to 2.5 mm or less, more preferably 1.6 mm or less, and more preferably 0.8 mm or less. If the thickness of the board is between 0.2mm and 0.8mm, it can be used as a material for textile machinery parts such as knitting machine needles.
[冷軋鋼板的製造方法] 其次，說明本發明的其中一種實施方式之冷軋鋼板的製造方法。 [Manufacturing method of cold rolled steel plate] Next, a method for manufacturing a cold-rolled steel plate according to one embodiment of the present invention will be described.
對於具有上述組成分的鋼胚料，依序地實施下列的工序，就可以製造出前述的冷軋鋼板。 (1)加熱 (2)熱軋 (3)冷卻 (4)捲取 (5)第1次退火 (6)冷軋 (7)第2次退火 (8)最終冷軋 並且將上述(6)以及(7)的工序，反覆地實施兩次以上。以下，將針對於各工序進行說明。 For the steel blank with the above composition, the above-mentioned cold-rolled steel plate can be produced by carrying out the following processes in sequence. (1)Heating (2) Hot rolling (3) Cooling (4) Take-up (5) First annealing (6)Cold rolling (7) Second annealing (8) Final cold rolling And the above-mentioned steps (6) and (7) are repeated two or more times. Each step will be described below.
(1)加熱 首先，對於具有上述的組成分之鋼胚料進行加熱。前述鋼胚料的製造方法，並未特別地限定，係可採用任何適合的方法來製造。例如前述鋼胚料的成分調整，係可以利用高爐暨轉爐法來進行調整，也可以利用電爐法來進行調整。此外，從熔鋼鑄造成鋼胚料時，可以利用連續鑄造法，也可以利用分塊輥軋法來進行。 (1)Heating First, the steel blank having the above composition is heated. The manufacturing method of the aforementioned steel blank is not particularly limited, and any suitable method can be used. For example, the composition of the aforementioned steel billet can be adjusted using the blast furnace and converter method, or the electric furnace method. In addition, when casting molten steel into steel blanks, continuous casting method or block rolling method can be used.
前述加熱雖然可以採用任何想用的方法，但是以使用加熱爐為佳。Although any desired method can be used for the aforementioned heating, a heating furnace is preferably used.
使用加熱爐來進行前述加熱的情況下，加熱爐的爐內溫度雖然並未特別地限定，但是基於為了使鋼成分均質化，並且使含在鋼胚料中之偏析以及未固溶碳化物溶解之觀點考量，將爐內溫度設定在1100℃以上為宜。When a heating furnace is used for the above-mentioned heating, the temperature in the heating furnace is not particularly limited. However, it is necessary to homogenize the steel components and dissolve segregation and unsolved carbides contained in the steel blank. From this point of view, it is appropriate to set the temperature in the furnace above 1100°C.
前述加熱時的保持時間雖然並未特別地限定，但是基於為了使未固溶碳化物充分地溶解之觀點考量，將保持時間設定在1小時以上為宜。Although the holding time during the aforementioned heating is not particularly limited, from the viewpoint of fully dissolving the non-solid-soluted carbide, the holding time is preferably set to 1 hour or more.
(2)熱軋 接下來，將加熱後的前述鋼胚料進行熱軋而成為熱軋鋼板。在前述的熱軋過程中，係可依據一般常用的方法來進行粗軋與精軋。 (2) Hot rolling Next, the heated steel blank is hot-rolled to become a hot-rolled steel plate. In the aforementioned hot rolling process, rough rolling and finish rolling can be carried out according to commonly used methods.
精軋入口側溫度為Ac3點以上 在前述熱軋時的精軋入口側溫度如果低於Ac3點的話，將會在熱軋後的鋼板中生成伸展後的肥粒鐵，而這種伸展後的肥粒鐵也會殘留在最終製成的冷軋鋼板中。其結果，將會促進粒界碳化物的生成，且抑制粒內碳化物的生成，因而導致韌性降低。因此，乃將前述熱軋時之精軋入口側溫度設定在Ac3點以上。另一方面，前述精軋入口側溫度的上限雖然並未特別地限定，但是以設定在1200℃以下為宜。 The temperature at the entrance side of finishing rolling is above Ac3 point If the temperature at the entrance side of the finishing rolling during hot rolling is lower than the Ac3 point, stretched fat iron will be generated in the hot-rolled steel plate, and this stretched fat iron will also remain in the final steel sheet. Into the cold-rolled steel plate. As a result, the formation of carbides at grain boundaries is promoted and the formation of carbides within grains is suppressed, resulting in a decrease in toughness. Therefore, the temperature at the entrance side of the finish rolling during the aforementioned hot rolling is set to be above the Ac3 point. On the other hand, the upper limit of the temperature at the entrance side of the finishing rolling is not particularly limited, but it is preferably set to 1200°C or less.
此外，前述Ac3點(℃)可利用下列數式(1)計算出來。 Ac3(℃)=910-(203×C 1/2)+(44.7×Si)-(30×Mn)-(11×Cr)+(400×Ti)+(460×Al)+(700×P)+(104×V)+38 …數式(1) 在上述數式(1)中的元素記號係指：各元素的含量(質量%)，如果未含有該元素的話，就視為含量是零。 In addition, the aforementioned Ac3 point (°C) can be calculated using the following equation (1). Ac3(℃)=910-(203×C 1/2 )+(44.7×Si)-(30×Mn)-(11×Cr)+(400×Ti)+(460×Al)+(700×P )+(104×V)+38…Equation (1) The element symbols in the above equation (1) refer to: the content (mass %) of each element. If the element is not contained, the content is regarded as zero.
(3)冷卻 從熱軋結束起迄冷卻開始的時間為2.0秒以下 其次，將前述熱軋鋼板進行冷卻。這個時候，如果從熱軋結束起迄冷卻開始的經過時間太長的話，將會生成粗大的肥粒鐵粒，並且含有Ti、Nb以及V的至少其中一種元素的將會不均質地析出在粒界。這種不均質的組織，在後續的冷軋及退火過程中也不會變得均質化，且會防礙碳化物生成在粒內。因此，乃將從前述熱軋結束起迄冷卻開始的時間設定為2.0秒以下。另一方面，從上述的觀點得知：從前述熱軋結束起迄冷卻開始的時間愈短愈好，因此，下限並未特別地限定。但是，基於工業性規模的生産之觀點考量，可以是設定在0.5秒以上，也可以是設定在0.8秒以上。 (3) Cooling The time from the end of hot rolling to the start of cooling is 2.0 seconds or less Next, the aforementioned hot-rolled steel plate is cooled. At this time, if the elapsed time from the end of hot rolling to the start of cooling is too long, coarse fat iron particles will be generated, and at least one element containing Ti, Nb, and V will be precipitated unevenly in the particles. boundary. This heterogeneous structure will not become homogenized during the subsequent cold rolling and annealing processes, and will prevent the formation of carbides within the grains. Therefore, the time from the end of the hot rolling to the start of cooling is set to 2.0 seconds or less. On the other hand, from the above-mentioned viewpoint, the shorter the time from the completion of the hot rolling to the start of cooling, the better, and therefore the lower limit is not particularly limited. However, from the viewpoint of industrial-scale production, it may be set to 0.5 seconds or more, or it may be set to 0.8 seconds or more.
平均冷卻速度為25℃/秒以上 如果前述冷卻時的平均冷卻速度低於25℃/秒的話，肥粒鐵粒將會變得粗大化，並且生成的碳化物將會呈局部性的分佈，在後續之反覆實施冷軋和退火處理時，碳化物將會集中生成在粒界，而抑制了粒內碳化物的生成。因此，乃將前述冷卻時的平均冷卻速度設定在25℃/秒以上。另一方面，平均冷卻速度的上限，雖然並未特別地限，但是冷卻速度太快的話，在後續的捲取工序時，將會因為捲取時的變態所導致的體積膨脹而使得捲取形狀變得不佳。因此，基於獲得良好的捲取形狀之觀點考量，係將平均冷卻速度設定在160℃/秒以下為宜，設定在150℃/秒以下更好。 The average cooling rate is more than 25℃/second If the average cooling rate during cooling is lower than 25°C/second, the fat iron particles will become coarser and the generated carbides will be locally distributed. Cold rolling and annealing treatments will be repeated in the subsequent steps. At this time, carbides will be concentrated in the grain boundaries, thus inhibiting the formation of carbides within the grains. Therefore, the average cooling rate during the aforementioned cooling is set to 25°C/second or more. On the other hand, although the upper limit of the average cooling rate is not particularly limited, if the cooling rate is too fast, the coiled shape will be changed due to volume expansion caused by deformation during coiling in the subsequent coiling process. become poor. Therefore, from the viewpoint of obtaining a good coiling shape, it is appropriate to set the average cooling rate to 160°C/second or less, and more preferably to set it to 150°C/second or less.
冷卻停止溫度為720℃ 又，如果在前述冷卻時的冷卻停止溫度太高的話，同樣地，肥粒鐵粒將會變得粗大化，因而在後續之反覆實施冷軋和退火處理時，將會抑制碳化物生成在粒內。因此，乃將冷卻停止溫度設定在720℃以下。另一方面，冷卻停止溫度的下限雖然並未特別地限定，但是冷卻停止溫度太低的話，將會因為後續之捲取時的變態所導致的體積膨脹而使得捲取形狀變得不佳。因此，乃將冷卻停止溫度設定在620℃以上為宜，設定在640℃以上更好。 Cooling stop temperature is 720℃ In addition, if the cooling stop temperature during the aforementioned cooling is too high, the fat iron particles will become coarser. Therefore, when the subsequent cold rolling and annealing treatments are repeatedly performed, the formation of carbides in the particles will be suppressed. within. Therefore, the cooling stop temperature is set to 720°C or lower. On the other hand, although the lower limit of the cooling stop temperature is not particularly limited, if the cooling stop temperature is too low, the coiled shape will become poor due to volume expansion due to subsequent transformation during coiling. Therefore, it is appropriate to set the cooling stop temperature to be above 620°C, and more preferably above 640°C.
(4)捲取 在停止進行前述冷卻之後，將冷卻後的前述熱軋鋼板捲取成鋼帶捲狀。這個時候的捲取溫度，雖然並未特別地限定，但是以設定在600～730℃為宜。藉由設定在這種溫度，可以使其析出板狀的雪明碳鐵而使得鋼帶捲的捲取形狀很穩定。 (4) Take-up After stopping the cooling, the cooled hot-rolled steel sheet is wound into a steel strip roll. The coiling temperature at this time is not particularly limited, but it is preferably set to 600 to 730°C. By setting this temperature, plate-shaped snow carbon iron can be precipitated and the coiling shape of the steel strip coil can be stabilized.
(5)第1次退火 退火溫度為650℃以上且780℃以下 退火時間為3小時以上 對於前述捲取後的熱軋鋼板，以退火溫度為650℃以上且780℃以下、退火時間為3小時以上的條件，來實施第1次退火。捲取後之熱軋鋼板的組織，是板狀的雪明碳鐵與肥粒鐵並列的波來鐵組織。波來鐵組織的熱穩定性很高，如果不在高溫下進行長時間保持的話，將不會形成均質化。為了將波來鐵組織崩解，而能夠藉由後續的冷軋和退火過程使其在粒內生成所期望的碳化物，必須是以650℃以上的退火溫度，3小時以上的退火時間來進行退火處理。另一方面，如果退火溫度高於780℃的話，其中有一部分優先地發生組織變化，而形成局部性之粗大的組織，因為變成了不均質的組織，因而難以獲得粒內碳化物，無法獲得所期望的碳化物個數密度。前述退火時間的上限，雖然並未特別地限定，但是，太長的話，不僅會降低生産性，退火的效果也會趨於飽和。因此，是設定在20小時以下為宜。 (5) First annealing Annealing temperature is 650℃ or above and 780℃ or below Annealing time is more than 3 hours The coiled hot-rolled steel sheet is first annealed under the conditions of an annealing temperature of 650° C. or more and 780° C. or less and an annealing time of 3 hours or more. The structure of the hot-rolled steel sheet after coiling is a plenum structure of plate-shaped snowy carbon iron and fat grain iron juxtaposed. The thermal stability of the Plein iron structure is very high. If it is not maintained at high temperature for a long time, it will not be homogenized. In order to disintegrate the perlite structure and generate the desired carbides in the particles through subsequent cold rolling and annealing processes, the annealing temperature must be above 650°C and the annealing time must be above 3 hours. Annealing treatment. On the other hand, if the annealing temperature is higher than 780°C, some parts of it will undergo structural changes preferentially and form a locally coarse structure. Since it becomes a heterogeneous structure, it is difficult to obtain intragranular carbides and cannot obtain all the desired properties. Desired carbide number density. Although the upper limit of the aforementioned annealing time is not particularly limited, if it is too long, not only will the productivity be reduced, but the annealing effect will also tend to be saturated. Therefore, it is appropriate to set it below 20 hours.
此外，在進行第1次退火之前，先對於熱軋鋼板進行酸洗也是很好的作法。In addition, it is also a good practice to pickle the hot-rolled steel plate before performing the first annealing.
(6)冷軋 (7)第2次退火 在熱軋後的鋼板中生成之板狀的碳化物。這種板狀的碳化物很穩定，所以很容易殘留至後續的工序，最終殘留下來之板狀碳化物也會成為發生孔洞、裂縫的原因，而導致韌性降低。因此，為了使板狀的碳化物利用退火時的加熱而再熔解之後，以粒子形狀的碳化物析出在粒內，乃針對於前述第1次退火之後的熱軋鋼板，反覆實施兩次以上之冷軋和第2次退火。 (6)Cold rolling (7) Second annealing Plate-shaped carbides formed in hot-rolled steel plates. This kind of plate-shaped carbide is very stable, so it is easy to remain in subsequent processes. The remaining plate-shaped carbide will eventually cause holes and cracks, leading to a decrease in toughness. Therefore, in order to precipitate the carbides in the form of particles in the particles after the plate-shaped carbides are re-melted by heating during annealing, this process is repeated two or more times for the hot-rolled steel sheet after the first annealing. Cold rolling and second annealing.
軋縮率為15%以上 前述冷軋時的軋縮率小於15%的話，粒界的碳化物將會變得粗大化，因此，生成在粒內之碳化物的個數密度會降低，並且粒內之碳化物的粒徑會變小。因此，乃將前述軋縮率設定在15%以上。另一方面，前述軋縮率的上限雖然並未特別地限定，但是以設定在70%以下為宜。 The reduction rate is more than 15% If the reduction ratio during cold rolling is less than 15%, the carbides at the grain boundaries will become coarse. Therefore, the number density of carbides generated within the grains will decrease, and the particle size of the carbides within the grains will decrease. will become smaller. Therefore, the aforementioned reduction ratio is set to 15% or more. On the other hand, the upper limit of the reduction ratio is not particularly limited, but it is preferably set to 70% or less.
退火溫度為600～800℃ 如果前述第2次退火時的退火溫度高於800℃的話，粒界的碳化物將會變得粗大化，因此，生成在粒內之碳化物的個數密度會降低，並且粒內之碳化物的粒徑會變小。因此，乃將前述退火溫度設定在800℃以下。另一方面，如果前述第2次退火時的退火溫度低於600℃的話，粒內碳化物的生成受到抑制，無法獲得所期望的粒徑。乃將前述退火溫度設定在600℃以上。 Annealing temperature is 600~800℃ If the annealing temperature during the second annealing is higher than 800°C, the carbides at the grain boundaries will become coarse. Therefore, the number density of carbides generated within the grains will decrease, and the carbides within the grains will The particle size will become smaller. Therefore, the aforementioned annealing temperature is set below 800°C. On the other hand, if the annealing temperature in the second annealing is lower than 600° C., the formation of intragranular carbides is suppressed, and the desired particle size cannot be obtained. The aforementioned annealing temperature is set above 600°C.
前述第2次退火時的昇溫速度雖然並未特別地限定，但是如果昇溫速度太慢的話，碳化物將會很容易生成在肥粒鐵粒界，因而粒內之碳化物的生成受到抑制。因此，基於可以更為提高能夠提昇韌性的效果之觀點考量，乃將前述第2次退火時的昇溫速度設定在50℃/小時以上為宜。另一方面，前述昇溫速度的上限，雖然並未特別地限定，但是以設定在200℃/秒以下為宜。Although the temperature rise rate during the second annealing is not particularly limited, if the temperature rise rate is too slow, carbides will easily be formed in the boundaries of fat iron grains, so the formation of carbides within the grains will be suppressed. Therefore, from the viewpoint of further enhancing the effect of improving toughness, it is appropriate to set the temperature rise rate during the second annealing to 50°C/hour or more. On the other hand, the upper limit of the temperature rise rate is not particularly limited, but it is preferably set to 200° C./second or less.
前述冷軋與第2次退火的反覆次數是設定在兩次以上。藉由將冷軋與退火反覆地實施兩次以上，可以促使碳化物的生成，最終而言，係可獲得所期望的粒內碳化物的大小和個數密度。前述反覆的次數之上限，並未特別地限定。但是，如果反覆次數超過五次的話，效果就已經飽和了，因此，將前述反覆次數設定在五次以下為宜。The number of repetitions of cold rolling and second annealing is set to two or more times. By repeatedly performing cold rolling and annealing two or more times, the formation of carbides can be promoted, and ultimately, the desired size and number density of intragranular carbides can be obtained. The upper limit of the number of repetitions is not particularly limited. However, if the number of repetitions exceeds five times, the effect will be saturated, so it is appropriate to set the number of repetitions to five or less.
(8)最終冷軋 軋縮率為20%以上 以上述的方式，反覆地實施兩次以上的冷軋與第2次退火之後，又實施一次軋縮率為20%以上的最終冷軋。藉由實施軋縮率為20%以上的最終冷軋，可以在進行最終的淬火暨回火時，在粒內析出所期望的個數密度的碳化物，而可以提昇韌性。雖然前述最終冷軋的軋縮率是愈大愈好，但是65%以上的話，鋼板會發生形狀不穩定的情事。因此，將前述軋縮率設定在小於65%為宜。 (8) Final cold rolling The reduction rate is more than 20% In the above manner, cold rolling and second annealing are repeatedly performed two or more times, and then final cold rolling with a reduction rate of 20% or more is performed once. By performing final cold rolling with a reduction rate of 20% or more, carbides with a desired number density can be precipitated in the grains during final quenching and tempering, thereby improving toughness. Although the larger the reduction ratio of the final cold rolling mentioned above is, the better, but if it exceeds 65%, the shape of the steel plate will become unstable. Therefore, it is appropriate to set the aforementioned reduction ratio to less than 65%.
以符合上述的條件來進行製造的話，可以製造出淬火暨回火處理後的韌性優異的冷軋鋼板。此外，對於最終製得的冷軋鋼板，也可以因應需求又實施表面處理。If the above-mentioned conditions are met, a cold-rolled steel plate with excellent toughness after quenching and tempering can be produced. In addition, the final cold-rolled steel plate can also be subjected to surface treatment according to needs.
[鋼製零件的製造方法] 又，在本發明的其中一種實施方式中，係可對於以上述製造方法所製造的冷軋鋼板，藉由實施淬火及回火來製造鋼製零件。前述淬火及回火的條件雖然並未特別地限定，但是為了獲得更高的韌性，是在淬火溫度為700℃以上且900℃以下、保持時間為1分鐘以上且小於60分鐘的條件下進行淬火，接下來，是在回火溫度為150～400℃、保持時間為20分鐘以上且3小時以下的條件下進行回火為宜。將前述淬火溫度設定在750℃以上且850℃以下更好。又，將前述回火溫度設定在200～300℃更好。 [Manufacturing method of steel parts] Furthermore, in one embodiment of the present invention, steel parts can be produced by quenching and tempering the cold-rolled steel plate produced by the above-mentioned production method. Although the conditions for the aforementioned quenching and tempering are not particularly limited, in order to obtain higher toughness, quenching is performed under the conditions of a quenching temperature of 700°C or more and 900°C or less, and a holding time of 1 minute or more and less than 60 minutes. , Next, it is advisable to perform tempering under the conditions of a tempering temperature of 150 to 400°C and a holding time of 20 minutes or more and 3 hours or less. It is more preferable to set the quenching temperature to 750°C or more and 850°C or less. Furthermore, it is more preferable to set the tempering temperature to 200 to 300°C.
前述淬火的冷卻方法，並未特別地限定，可以採用任何可行的方法。前述冷卻，例如：可以是空冷、水淬火、油淬火的其中任何一種。The cooling method of the aforementioned quenching is not particularly limited, and any feasible method can be used. The aforementioned cooling may be, for example, any one of air cooling, water quenching, and oil quenching.
此外，在實施前述淬火暨回火之前，亦可先進行想要施作的加工來將冷軋鋼板預先做成所期望的形狀。 [實施例] In addition, before performing the aforementioned quenching and tempering, the cold-rolled steel plate may be formed into a desired shape by performing the desired processing. [Example]
以下，為了確認本發明的作用效果，先依照以下所述的步驟製造出冷軋鋼板，然後對於所製得的冷軋鋼板之淬火暨回火之後的韌性進行評比。In the following, in order to confirm the effect of the present invention, a cold-rolled steel plate was first produced according to the steps described below, and then the toughness of the produced cold-rolled steel plate after quenching and tempering was evaluated.
首先，利用轉爐進行熔製具有表1所示的組成分之熔鋼，利用連續鑄造法予以做成鋼胚料。接下來，對於前述鋼胚料，依序地實施：加熱、熱軋、冷卻、捲取、第1次退火、冷軋、第2次退火、以及最終冷軋，而做成最終板厚度為約0.4mm的冷軋鋼板。各工序是在如表2、表3所示的條件下實施的，冷軋以及第2次退火，則是反覆地實施了如表2、表3所示的次數。First, molten steel having the composition shown in Table 1 is melted in a converter, and a steel blank is produced by continuous casting. Next, the above-mentioned steel blank is sequentially implemented: heating, hot rolling, cooling, coiling, first annealing, cold rolling, second annealing, and final cold rolling, so that the final plate thickness is approximately 0.4mm cold rolled steel plate. Each process was performed under the conditions shown in Tables 2 and 3. Cold rolling and second annealing were repeated the number of times shown in Tables 2 and 3.
(碳化物的測定方法) 從所製得的測試用材料採取出：組織觀察用測試片。將前述組織觀察用測試片之輥軋方向的斷面(L斷面)進行研磨之後，使用1～3體積%的硝酸腐蝕液對於前述研磨面進行腐蝕以使組織浮現出來。接下來，使用掃描型電子顯微鏡(Scanning Electron Microscope(SEM))對於前述組織觀察用測試片的表面，以3000倍的倍率進行拍攝而取得組織圖像。利用切斷法從所取得的組織圖像來測定生成在粒內之Nb、Ti、V系的碳化物的粒徑，以及藉由計數位在測定視野內之碳化物的個數來計算出個數密度。並且算出三個測定視野的平均值，來作為前述碳化物之粒徑與個數密度。將測定結果標示於表4和表5。對於Nb、Ti、V系之碳化物的識別，則是採用掃描型電子顯微鏡-X射線能量散布分析(Energy Dispersive x-ray Spectroscopy(SEM-EDS分析))來進行識別。針對於顯微鏡的觀察視野，進行元素標定，將雪明碳鐵與雪明碳鐵以外的碳化物分開，將雪明碳鐵以外的碳化物當成Nb、Ti、V系的碳化物。 (Measurement method of carbide) Take out from the prepared test materials: test pieces for tissue observation. After grinding the cross section (L cross section) of the test piece in the rolling direction of the test piece for structural observation, the polished surface is etched using a nitric acid etching solution of 1 to 3 volume % to expose the structure. Next, a scanning electron microscope (Scanning Electron Microscope (SEM)) was used to photograph the surface of the test piece for tissue observation at a magnification of 3000 times to obtain a tissue image. The particle size of Nb, Ti, and V-based carbides generated in the particles is measured from the obtained tissue image using the cutting method, and the individual is calculated by counting the number of carbides located within the measurement field of view. Number density. And the average value of the three measurement visual fields was calculated as the particle size and number density of the carbide. The measurement results are shown in Table 4 and Table 5. For the identification of Nb, Ti, and V series carbides, scanning electron microscopy-X-ray energy dispersion analysis (Energy Dispersive x-ray Spectroscopy (SEM-EDS analysis)) is used. Based on the observation field of the microscope, element calibration is performed to separate snow carbon iron from carbides other than snow carbon iron, and carbides other than snow carbon iron are regarded as Nb, Ti, and V series carbides.
(淬火暨回火後的韌性) 其次，為了評比對於所製得的冷軋鋼板實施了淬火暨回火之後的韌性，乃依照以下的步驟進行了試驗，來測定了夏比衝擊試驗的衝擊值。首先，對於所製得的冷軋鋼板實施了淬火以及回火。前述淬火，是將該冷軋鋼板在預先加熱到800℃的爐內保持10分鐘之後，再置入溫度為80℃的油內來進行油淬火。前述回火，則是將淬火後的冷軋鋼板在預先加熱到250℃的爐內保持1小時之後，進行空冷。 (Toughness after quenching and tempering) Secondly, in order to evaluate the toughness of the produced cold-rolled steel plates after quenching and tempering, a test was conducted according to the following steps to measure the impact value of the Charpy impact test. First, the produced cold-rolled steel plate was quenched and tempered. The aforementioned quenching is performed by holding the cold-rolled steel sheet in a furnace preheated to 800°C for 10 minutes, and then placing it in oil at a temperature of 80°C for oil quenching. The aforementioned tempering involves holding the quenched cold-rolled steel sheet in a furnace preheated to 250°C for 1 hour and then air-cooling.
然後，進行夏比衝擊試驗來測定了衝擊值。將測定結果標示於表4和表5。在進行前述夏比衝擊試驗時，是使用了從已經過了淬火暨回火後的冷軋鋼板採取出來之U型缺口深度為2.5mm且U型缺口半徑為0.1mm(U型缺口寬度為0.2mm)的試驗片。前述試驗片的U型缺口是利用放電加工而形成的。在本發明中，如果衝擊值達到8J/cm 2以上的話，就予以判斷為淬火暨回火之後的韌性優異。 Then, a Charpy impact test was performed to measure the impact value. The measurement results are shown in Table 4 and Table 5. When conducting the aforementioned Charpy impact test, a U-shaped notch with a depth of 2.5mm and a radius of 0.1mm (a U-shaped notch width of 0.2) taken from a cold-rolled steel plate that has been quenched and tempered was used. mm) test piece. The U-shaped notch in the test piece was formed by electric discharge machining. In the present invention, if the impact value reaches 8 J/cm 2 or more, it is judged that the toughness after quenching and tempering is excellent.
由表1至表5所示的結果可以看出：符合本發明的條件之冷軋鋼板，都是具有優異之淬火暨回火後的韌性。根據本發明，係可以兼具有：因為Nb、Ti、V系的碳化物而獲得的高硬度以及優異的韌性，因此，藉由使用本發明的冷軋鋼板，可以製造出兼具有高水準的硬度及韌性的鋼製零件。因此，本發明的冷軋鋼板可以極適用於作為纖維機械用零件、軸承零件以及刀具之類的各種鋼製零件的素材。From the results shown in Tables 1 to 5, it can be seen that the cold-rolled steel plates that meet the conditions of the present invention all have excellent toughness after quenching and tempering. According to the present invention, it is possible to have both high hardness and excellent toughness due to Nb, Ti, and V-based carbides. Therefore, by using the cold-rolled steel sheet of the present invention, it is possible to produce a cold-rolled steel sheet having both high-quality Hardness and toughness of steel parts. Therefore, the cold-rolled steel sheet of the present invention is extremely suitable as a material for various steel parts such as fiber machinery parts, bearing parts, and cutting tools.
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| JP2017190494A (en) * | 2016-04-13 | 2017-10-19 | 日新製鋼株式会社 | Wear resistant steel sheet excellent in toughness |
| TW202014526A (en) * | 2018-10-02 | 2020-04-16 | 日商日本製鐵股份有限公司 | Steel sheet for carburizing and production method for steel sheet for carburizing being superior in formability and toughness after carburizing |
| WO2021090472A1 (en) * | 2019-11-08 | 2021-05-14 | 株式会社特殊金属エクセル | High-carbon cold-rolled steel sheet and production method therefor, and mechanical parts made of high-carbon steel |
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| JP2015190036A (en) * | 2014-03-28 | 2015-11-02 | 日新製鋼株式会社 | Steel sheet for fiber machine component and manufacturing method therefor |
| JP2017190494A (en) * | 2016-04-13 | 2017-10-19 | 日新製鋼株式会社 | Wear resistant steel sheet excellent in toughness |
| TW202014526A (en) * | 2018-10-02 | 2020-04-16 | 日商日本製鐵股份有限公司 | Steel sheet for carburizing and production method for steel sheet for carburizing being superior in formability and toughness after carburizing |
| WO2021090472A1 (en) * | 2019-11-08 | 2021-05-14 | 株式会社特殊金属エクセル | High-carbon cold-rolled steel sheet and production method therefor, and mechanical parts made of high-carbon steel |
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