WO2022137697A1 - 温間鍛造用肌焼鋼及びこれを用いて製造した鍛造粗形材 - Google Patents
温間鍛造用肌焼鋼及びこれを用いて製造した鍛造粗形材 Download PDFInfo
- Publication number
- WO2022137697A1 WO2022137697A1 PCT/JP2021/035738 JP2021035738W WO2022137697A1 WO 2022137697 A1 WO2022137697 A1 WO 2022137697A1 JP 2021035738 W JP2021035738 W JP 2021035738W WO 2022137697 A1 WO2022137697 A1 WO 2022137697A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- less
- forging
- hardness
- warm forging
- ferrite
- Prior art date
Links
- 238000005242 forging Methods 0.000 title claims abstract description 77
- 229910000760 Hardened steel Inorganic materials 0.000 title abstract description 4
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 49
- 239000010959 steel Substances 0.000 claims description 49
- 229910000859 α-Fe Inorganic materials 0.000 claims description 44
- 239000000463 material Substances 0.000 claims description 23
- 239000000126 substance Substances 0.000 claims description 15
- 239000000203 mixture Substances 0.000 claims description 14
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 5
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910052719 titanium Inorganic materials 0.000 claims description 4
- 238000005255 carburizing Methods 0.000 description 14
- 239000011572 manganese Substances 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 239000011651 chromium Substances 0.000 description 9
- 238000003754 machining Methods 0.000 description 7
- 238000011156 evaluation Methods 0.000 description 6
- 239000010936 titanium Substances 0.000 description 6
- 238000005520 cutting process Methods 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 5
- 239000010955 niobium Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000005265 energy consumption Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000009661 fatigue test Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000011733 molybdenum Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000013467 fragmentation Methods 0.000 description 1
- 238000006062 fragmentation reaction Methods 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 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
- 230000003287 optical effect Effects 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
- B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
-
- 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
-
- 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
- C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
-
- 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
-
- 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
Definitions
- the present invention relates to a skin-baked steel for warm forging and a forged rough shape material manufactured using the same.
- Steel parts for transmissions represented by gears are often manufactured by subjecting a forged rough shape material obtained by hot forging to machining and surface hardening treatment.
- Hot forging has a problem that energy consumption is relatively large because the forging heating temperature is high, the yield is poor due to the generation of scale on the surface, and it is difficult to secure dimensional accuracy.
- the forged rough shape material after hot forging does not have good machinability as it is due to the improvement in hardness, it is essential to perform heat treatment to reduce the hardness before machining, which also causes a problem of energy consumption. Is.
- warm forging has a lower forging temperature than hot forging, so energy consumption is low, and the amount of scale generated is small, so the yield is good, the dimensional accuracy is good, and the margin for the next process is small.
- Patent Document 1 mentions warm forging and machinability, but does not describe improvement of machinability when cutting is performed after warm forging.
- Patent Document 2 describes warm forging and machinability, the machinability after warm forging has not been evaluated, and the final strength cannot be expected from the viewpoint of chemical composition. Only steel is mentioned.
- Patent Document 3 describes warm forging, subsequent evaluation of machinability has not been made. Therefore, it is not possible to derive from Patent Documents 1 to 3 how it is necessary to devise the chemical composition of steel in order to improve the machinability without applying heat treatment after warm forging.
- Japanese Unexamined Patent Publication No. 2007-321211 Japanese Unexamined Patent Publication No. 2001-131686 Japanese Unexamined Patent Publication No. 60-262941
- the present invention has been made in view of this background, and provides a skin-baked steel having excellent machinability after warm forging and a forged rough shape material having excellent machinability which has been warm-forged using the same. It is something to try.
- One aspect of the present invention is a skin-baked steel for warm forging having a forging temperature of 850 ° C to 1100 ° C.
- C 0.15 to 0.23%
- Si 0.60 to 0.95%
- Mn 0.60 to 1.20%
- P 0.035% or less
- S 0.035. % Or less
- Cr 1.50% or less (excluding 0%)
- Al 0.050% or less
- Ti 0.01 to 0.05%
- B 0.0005 to 0.0050%
- N 0
- Nb 0.01 to 0.05% as an optional element
- the balance has a chemical composition of Fe and unavoidable impurities.
- Equation 1 90 ⁇ -120 * C + 20.1 * Si-5.3 * Mn-8.5 * Mo + 96 ⁇ 80
- Equation 2 160 ⁇ 40 * Si + 39 * Mn + 10 * Cr + 30 * Mo + 84 ⁇ 145, (However, the element symbol in the formulas 1 and 2 means the content rate (mass%) of each element.) It is in the skin-baked steel for warm forging that satisfies the content rate (mass%).
- Another aspect of the present invention is a forged rough shape material obtained by performing warm forging at a forging temperature of 850 ° C to 1100 ° C using the above-mentioned skin-baked steel for warm forging.
- the surface hardness is 200 HV or less, It has a metallic structure with a ferrite ratio of 80% to 90%, and has a ferrite ratio of 80% to 90%.
- the skin-baked steel that is within the range of the above-mentioned basic chemical composition and has a specific chemical composition having the above formulas 1 and 2 is heat-treated after being warm forged. It is possible to obtain an excellent rough forged material that can ensure machinability without any problem in manufacturing even if the above is omitted.
- the above-mentioned hard forged steel for warm forging is a steel planned to be subjected to warm forging having a forging temperature of 850 ° C to 1100 ° C. If the forging temperature of warm forging is too low, the deformation resistance during forging will increase and it will be difficult to form the desired shape. Since the effect is reduced, the temperature is set to 1100 ° C or lower.
- This warm forged skin-baked steel has a basic chemical composition of C: 0.15 to 0.23%, Si: 0.60 to 0.95%, Mn: 0.60 to% in mass%. 1.20%, P: 0.035% or less, S: 0.035% or less, Cr: 1.50% or less (excluding 0%), Al: 0.050% or less, Ti: 0.01 to 0 It contains 0.05%, B: 0.0005 to 0.0050%, N: 0.0020 to 0.0200%, and has a chemical composition in which the balance consists of Fe and unavoidable impurities.
- C 0.15 to 0.23%
- C (carbon) is contained in an amount of 0.15% or more in order to secure the necessary strength after quenching and to prevent deterioration of chip disposability.
- the content is set to 0.23% or less.
- Si 0.60 to 0.95%
- Si silicon
- Si (silicon) is an element necessary for ensuring machinability. If the Si content is too low, the ferrite hardness becomes low, the chip dispersibility deteriorates, and the wear of the tool may be promoted. Therefore, the content is 0.60% or more. On the other hand, if the Si content is too high, the hardness may increase too much and the machinability performed after forging may decrease, so the content is set to 0.95% or less.
- Mn 0.60 to 1.20%; Mn (manganese) is contained in an amount of 0.60% or more in order to secure the internal hardness strength after carburizing.
- Mn content is too high, the retained austenite may increase and the hardness of the carburized layer may decrease, and the hardness after forging may increase, resulting in deterioration of machinability. 20% or less.
- P 0.035% or less; If the content of P (phosphorus) is too high, it segregates at the grain boundaries and causes a decrease in fatigue strength, so the content should be 0.035% or less.
- S 0.035% or less; If the content of S (sulfur) is too high, sulfide-based inclusions will increase and cause a decrease in fatigue strength, so the content should be 0.035% or less.
- Cr 1.50% or less (excluding 0%); Cr (chromium) is effective in ensuring internal hardness by improving hardenability, but if the content is too high, the hardness after warm forging may increase and the machinability may decrease. 1.50% or less.
- Al 0.050% or less; If the content of Al (aluminum) is too high, coarse precipitates of AlN may increase and the toughness may deteriorate. Therefore, the content of Al (aluminum) is set to 0.050% or less.
- Ti 0.01-0.05%; Ti (titanium) is contained in an amount of 0.01% or more because it is effective in obtaining an action of consuming N as TiN, a so-called N kill action, in order to prevent N from binding to B.
- Ti titanium
- the content of Ti is too high, there is a concern that the strength may decrease due to the generation of TiN, and abnormal wear of the tool during cutting may be accelerated, so the content is set to 0.05% or less.
- B 0.0005 to 0.0050%
- B (boron) is contained in an amount of 0.0005% or more in order to obtain the effect of improving the strength by strengthening the grain boundaries.
- the upper limit is set to 0.0050%.
- N 0.0020-0.0200%; Since N (nitrogen) becomes AlN and has an effect of suppressing crystal grain coarsening due to the pinning effect, it is contained in an amount of 0.0020% or more. On the other hand, if the N content is too high, coarse precipitates of AlN may increase and the toughness may deteriorate, so the content should be 0.0200% or less.
- Mo as an optional element: 0.20% or less; Mo (molybdenum) is an optional additive element and does not need to be positively contained.
- the content may be 0%, but it may be contained in a small amount as an impurity. Since Mo is an element effective for improving hardenability due to its content, it can be added in a small amount as needed. On the other hand, if the Mo content is too high, there is a risk of cost increase and deterioration of machinability, so the Mo content is limited to 0.20% or less.
- Nb as an optional element: 0.01-0.05%; Nb (niobium) is an optional additive element and does not need to be positively contained, but the effect of grain refinement can be obtained by containing 0.01% or more. On the other hand, if the Nb content is too high, the carburizing property may deteriorate, so the content is limited to 0.05% or less.
- the ferrite ratio and the ferrite hardness after warm forging can be controlled within the optimum range, whereby the machinability can be ensured.
- Equation 1 90 ⁇ -120 * C + 20.1 * Si-5.3 * Mn-8.5 * Mo + 96 ⁇ 80; Equation 1 is a relational equation effective for estimating the ferrite ratio in the metal structure after warm forging. The value of the equation does not completely match the ferrite ratio as it is, but the larger the value of Equation 1, the higher the ferrite ratio tends to be, and when the value is in the range of 80 or more and 90 or less, after warm forging. It becomes easy to control the ferrite ratio of the above in the optimum range.
- Equation 2 160 ⁇ 40 * Si + 39 * Mn + 10 * Cr + 30 * Mo + 84 ⁇ 145; Equation 2 is a relational equation effective for estimating the ferrite hardness in the metal structure after warm forging.
- the value of the equation does not completely match the ferrite hardness as it is, but the larger the value of the equation 2, the higher the ferrite hardness tends to be, and when the value is in the range of 145 or more and 160 or less, warm forging is performed. It becomes easy to control the later ferrite hardness within the optimum range.
- the forged rough shape material obtained by warm forging at a forging temperature of 850 ° C. to 1100 ° C. using the above-mentioned hot forging skin-baked steel has a surface hardness of 200 HV or less and a ferrite ratio. It has a metal structure of 80% to 90% and has a ferrite hardness of 140 mHV to 160 mHV.
- the surface hardness of the forged rough material that is, the macro hardness, to 200 HV or less, it is possible to perform cutting without performing heat treatment after forging.
- the chip processability is ensured and the tool wear amount is deteriorated.
- the effect of improving machinability can be obtained by suppressing the above.
- the ferrite ratio when the ferrite ratio is lower than the above lower limit, the pearlite area ratio increases, the macro hardness (surface hardness) increases, and the effect of suppressing deterioration of tool wear due to the change from hot forging to warm forging. May decrease. Further, when the ferrite ratio exceeds the above upper limit value, the macro hardness (surface hardness) may become too low and the chip repersibility may deteriorate.
- the chip dispersibility may be deteriorated, and when the ferrite hardness is higher than the above upper limit value, the effect of suppressing deterioration of the tool wear amount may be lowered.
- Example 1 Examples of the warm forged skin-baked steel and the forged rough profile of this example will be described.
- Tables 1 and 2 forged rough shaped materials were prepared using 29 types of steel materials (steel types 1 to 29) having different chemical components, and various evaluations were carried out.
- steel grades 1 to 16 are examples that satisfy the conditions of the present invention
- steel grades 17 to 28 are comparative examples that do not satisfy some conditions
- steel grade 29 is a conventional steel. It is JIS SCr420.
- each forged rough shape material steel ingots obtained by melting various steel materials in an electric furnace are forged to produce billets having a diameter of 65 mm ⁇ , and each of them has a steel grade 1 at the forging temperature shown in Table 3 described later.
- No. 28 was warm forged to obtain a forged rough shape material.
- the warm forged rough forged materials (steel grades 1 to 28) were not heat-treated after forging.
- the steel grade 29 was prepared as a comparison in order to confirm the effect of the component optimization + application of warm forging suitable for warm forging.
- the conventional steel, SCr420 is subjected to hot forging, which has been conventionally performed, and then heat-treated at 900 ° C. for 1 hour in order to improve workability.
- Mo which is an optional additive element, was contained as an impurity in a small amount due to the dissolution base material. Therefore, Tables 1 and 2 also show the analytical values of Mo contained as impurities.
- ⁇ Ferrite ( ⁇ ) ratio and ferrite ( ⁇ ) hardness> Assuming the machining of the gear-corresponding part after forging, the cross section near the surface of the forged rough profile corresponding to the gear-corresponding part is subjected to nighttal corrosion, and then observed using an optical microscope, and the area of ferrite is observed. The rate was determined by image analysis, and this value was taken as the ferrite rate. As the ferrite hardness, the value of the micro Vickers hardness measured in the ferrite structure portion of the above cross section was used.
- the tool wear amount was evaluated by measuring the wear amount of the flank of the cutting tool.
- the result of the tool wear amount of the standard SCr20 equivalent steel type 29 heat-treated post-hot forging heat treatment additional treatment product
- passes ( ⁇ ) passes-treated post-hot forging heat treatment additional treatment product
- pass (x) passes-treated post-hot forging heat treatment additional treatment product
- a rough shape material for a test piece is produced by the same manufacturing method as the above-mentioned forged rough shape material, and then a test piece of 12 square ⁇ 110 length is produced by machining (depth 2 mm, angle 60 degrees in the center of the test piece).
- a test piece was prepared by performing a carburizing heat treatment on the notch bottom (with a notch of R1.0) and then finishing the surface by polishing the surface on the notch side by 0.2 mm.
- the carburizing heat treatment conditions were such that carburizing was performed under the conditions of carburizing temperature: 950 ° C. ⁇ 150 min and Cp: 0.85, then oil-cooled and quenched, and then tempered at 150 ° C. ⁇ 1 Hr.
- the strength evaluation test after carburizing was carried out by a 3-point bending fatigue test.
- the fatigue test was carried out under the condition of a frequency of 1 Hz, and was evaluated by obtaining a low-cycle bending fatigue strength that fractures after several 100 repetitions. Then, a case of equality or higher than the result of the steel grade 29 as a standard was evaluated as "pass ( ⁇ )", and a case lower than the standard was evaluated as "fail (x)".
- the steel grade 17 had a low carbon (C) content, so that the strength after carburizing was too low.
- the steel grade 18 Since the steel grade 18 has a high carbon (C) content, the macro hardness becomes too high, and the amount of tool wear deteriorates.
- the silicon (Si) content of the steel grade 19 is low, the ferrite hardness becomes too low, and the chip treatment property deteriorates.
- the steel grade 20 has a high silicon (Si) content, the macro hardness becomes too high, and the amount of tool wear deteriorates.
- the macrohardness increases due to the high carbon (C) and manganese (Mn) contents, the tool wear amount deteriorates, and the carburized layer due to the increase in the retained austenite due to the high Mn content. Due to the decrease in hardness of the manganese, the strength after carburizing was rejected.
- the steel grade 23 has a high molybdenum (Mo) content, the macro hardness increased and the tool wear amount deteriorated.
- the steel grade 24 has a high chromium (Cr) content, the macro hardness increased and the tool wear amount deteriorated.
- the chemical composition did not satisfy the formula 1 and was out of the lower limit, so that the ferrite ratio became low, the macro hardness increased, and the tool wear amount deteriorated.
- the chemical composition did not satisfy the formula 2 and was out of the lower limit, so that the ferrite hardness became low and the chip treatment property deteriorated.
- the chemical composition did not satisfy the formula 1 and the upper limit was exceeded, so that the ferrite ratio became low, the macro hardness became low, and the chip treatment property deteriorated.
- the chemical composition did not satisfy the formula 2 and exceeded the upper limit, so that the ferrite hardness increased and the tool wear amount deteriorated.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Forging (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
質量%において、C:0.15~0.23%、Si:0.60~0.95%、Mn:0.60~1.20%、P:0.035%以下、S:0.035%以下、Cr:1.50%以下(0%は除く)、Al:0.050%以下、Ti:0.01~0.05%、B:0.0005~0.0050%、N:0.0020~0.0200%を含み、
任意元素としてMo:0.20%以下、任意元素としてNb:0.01~0.05%を含み、
残部がFe及び不可避的不純物からなる化学成分組成を有し、
式1:90≧-120*C+20.1*Si-5.3*Mn-8.5*Mo+96≧80、及び、
式2:160≧40*Si+39*Mn+10*Cr+30*Mo+84≧145、
(ただし、式1及び式2における元素記号は、各元素の含有率(質量%)を意味する。)を満足する、温間鍛造用肌焼鋼にある。
表面硬さが200HV以下であり、
フェライト率が、80%~90%である金属組織を有し、かつ、
フェライト硬さが、140mHV~160mHVである、鍛造粗形材にある。
C(炭素)は、焼き入れ後の必要な強度確保、及び、切り屑処理性悪化防止のために0.15%以上含有させる。一方、C含有率が高すぎると、マクロ硬さが高くなりすぎて鍛造後に行う機械加工性が低下するおそれがあるため、0.23%以下とする。
Si(ケイ素)は被削性確保に必要な元素である。Si含有率が低すぎるとフェライト硬さが低くなり、切り屑処理性が悪化して、工具の摩耗が促進されるおそれがあるため、0.60%以上含有させる。一方、Si含有率が高すぎると、硬さが増加しすぎて鍛造後に行う機械加工性が低下するおそれがあるため、0.95%以下とする。
Mn(マンガン)は、浸炭後の内部硬さ強度を確保するために0.60%以上含有させる。一方、Mn含有率が高すぎると、残留オーステナイトが増加して浸炭層の硬さ低下の懸念が生じるとともに、鍛造後の硬さが上昇し被削性の劣化を招くおそれがあるため、1.20%以下とする。
P(リン)は、含有率が高すぎると、粒界に偏析して疲労強度低下の原因となるため、0.035%以下とする。
S(硫黄)は、含有率が高すぎると、硫化物系介在物が増加して疲労強度低下の原因となるため、0.035%以下とする。
Cr(クロム)は、焼入れ性の向上による内部硬さの確保に有効であるが、含有率が高すぎると、温間鍛造後の硬さが上昇し、被削性低下するおそれがあるため、1.50%以下とする。
Al(アルミニウム)は、含有率が高すぎると、AlNの粗大な析出物が増加して靭性が悪化するおそれがあるため、0.050%以下とする。
Ti(チタン)は、NがBと結びつくのを防止するためTiNとしてNを消費する作用、いわゆるNキル作用を得るのに有効であるため、0.01%以上含有させる。一方、Tiは、含有率が高すぎると、TiN生成による強度低下の懸念、及び、切削時の工具の異常摩耗が早くなるおそれがあるため、0.05%以下とする。
B(ホウ素)は、粒界強化による強度向上効果を得るため、0.0005%以上含有させる。一方、B含有率が高くなりすぎても、前述の効果が飽和するため、上限を0.0050%とする。
N(窒素)は、AlNとなって、ピン止め効果により結晶粒粗大化を抑制する効果があるため、0.0020%以上含有させる。一方、N含有率が高すぎると、AlNの粗大な析出物が増加して靭性が悪化するおそれがあるため、0.0200%以下とする。
Mo(モリブデン)は、任意添加元素であり、積極的に含有させる必要はなく、含有率0%でもよいが、不純物として少量含有する場合もある。そして、Moは、その含有により、焼入れ性向上に有効な元素であるので、必要に応じ少量添加することができる。一方、Mo含有率が高すぎると、コストアップ及び切削加工性劣化のおそれがあるため、0.20%以下に制限する。
Nb(ニオブ)は、任意添加元素であり、積極的に含有させる必要はないが、0.01%以上含有することによって結晶粒微細化の効果を得ることができる。一方、Nb含有率が高すぎると、浸炭性が劣化するおそれがあるため、0.05%以下に制限する。
式1は、温間鍛造後における金属組織中のフェライト率の推定に有効な関係式である。式の値がそのままフェライト率と完全に一致するわけではないが、式1の値が大きいほどフェライト率が高くなる傾向となり、その値が80以上90以下の範囲にある場合に、温間鍛造後のフェライト率を最適な範囲に制御することが容易となる。
式2は、温間鍛造後における金属組織中のフェライト硬さの推定に有効な関係式である。式の値がそのままフェライト硬さと完全に一致するわけではないが、式2の値が大きいほどフェライト硬さが高くなる傾向となり、その値が145以上160以下の範囲にある場合に、温間鍛造後のフェライト硬さを最適な範囲に制御することが容易となる。
本例の温間鍛造用肌焼鋼及び鍛造粗形材に係る実施例について説明する。
本例では、表1及び表2に示すごとく、化学成分が異なる29種類の鋼材(鋼種1~29)を用いて鍛造粗形材を作製し、各種評価を実施した。表1、表2に示す鋼のうち、鋼種1~16が、本発明の条件を満足する実施例、鋼種17~28が、一部の条件を満足しない比較例、鋼種29が従来鋼であるJISのSCr420である。
鍛造後の歯車相当部分の機械加工を想定して、歯車相当部分の位置に相当する上記鍛造粗形材の表面近傍の断面をナイタール腐食させた後、光学顕微鏡を用いて観察し、フェライトの面積率を、画像解析により求め、この値をフェライト率とした。フェライト硬さとしては、上記断面のフェライト組織部分において測定したマイクロビッカース硬さの値とした。
鍛造後の歯車相当部分の機械加工を想定して、歯車相当部分の位置に相当する上記鍛造粗形材の表面近傍の断面において測定したビッカース硬さをマクロ硬さとした。
上記鍛造粗形材の表面を以下の条件で切削して旋削性評価を行った。
・切削速度:250m/min
・切込:0.8mm
・送り:0.4mm/rev
・潤滑:wet
上記鍛造粗形材と同じ製造方法により、試験片用粗形材を作製し、その後機械加工にて12角×長さ110の試験片を作製(試験片中央に深さ2mm、角度60度、ノッチ底R1.0のノッチ付き)し、これに浸炭熱処理を実施した後、ノッチ側の面を0.2mm研磨する表面の仕上げ加工をすることにより、試験片を作製した。浸炭熱処理条件は、浸炭温度:950℃×150min、Cp:0.85の条件で浸炭処理した後、油冷して焼入れし、その後、150℃×1Hrの焼き戻し処理を行う条件とした。
Claims (2)
- 鍛造温度が850℃~1100℃である温間鍛造用の肌焼鋼であって、
質量%において、C:0.15~0.23%、Si:0.60~0.95%、Mn:0.60~1.20%、P:0.035%以下、S:0.035%以下、Cr:1.50%以下(0%は除く)、Al:0.050%以下、Ti:0.01~0.05%、B:0.0005~0.0050%、N:0.0020~0.0200%を含み、
任意元素としてMo:0.20%以下、任意元素としてNb:0.01~0.05%を含み、
残部がFe及び不可避的不純物からなる化学成分組成を有し、
式1:90≧-120*C+20.1*Si-5.3*Mn-8.5*Mo+96≧80、及び、
式2:160≧40*Si+39*Mn+10*Cr+30*Mo+84≧145、
(ただし、式1及び式2における元素記号は、各元素の含有率(質量%)を意味する。)を満足する、温間鍛造用肌焼鋼。 - 請求項1に記載の温間鍛造用肌焼鋼を用い、鍛造温度が850℃~1100℃の温間鍛造を施して得られた鍛造粗形材であって、
表面硬さが200HV以下であり、
フェライト率が、80%~90%である金属組織を有し、かつ、
フェライト硬さが、140mHV~160mHVである、
鍛造粗形材。
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202180079319.6A CN116457118A (zh) | 2020-12-22 | 2021-09-29 | 温锻用表面硬化钢以及使用其制造的锻造粗型材 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2020-212173 | 2020-12-22 | ||
JP2020212173A JP7188432B2 (ja) | 2020-12-22 | 2020-12-22 | 温間鍛造用肌焼鋼及びこれを用いて製造した鍛造粗形材 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2022137697A1 true WO2022137697A1 (ja) | 2022-06-30 |
Family
ID=82157478
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2021/035738 WO2022137697A1 (ja) | 2020-12-22 | 2021-09-29 | 温間鍛造用肌焼鋼及びこれを用いて製造した鍛造粗形材 |
Country Status (3)
Country | Link |
---|---|
JP (1) | JP7188432B2 (ja) |
CN (1) | CN116457118A (ja) |
WO (1) | WO2022137697A1 (ja) |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012072427A (ja) * | 2010-09-28 | 2012-04-12 | Kobe Steel Ltd | 肌焼鋼およびその製造方法 |
WO2012046779A1 (ja) * | 2010-10-06 | 2012-04-12 | 新日本製鐵株式会社 | 肌焼鋼及びその製造方法 |
JP2015134949A (ja) * | 2014-01-17 | 2015-07-27 | Jfe条鋼株式会社 | 肌焼鋼および機械構造用部品 |
JP2021154387A (ja) * | 2020-03-25 | 2021-10-07 | 愛知製鋼株式会社 | 浸炭用鍛造材の製造方法 |
-
2020
- 2020-12-22 JP JP2020212173A patent/JP7188432B2/ja active Active
-
2021
- 2021-09-29 WO PCT/JP2021/035738 patent/WO2022137697A1/ja active Application Filing
- 2021-09-29 CN CN202180079319.6A patent/CN116457118A/zh active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2012072427A (ja) * | 2010-09-28 | 2012-04-12 | Kobe Steel Ltd | 肌焼鋼およびその製造方法 |
WO2012046779A1 (ja) * | 2010-10-06 | 2012-04-12 | 新日本製鐵株式会社 | 肌焼鋼及びその製造方法 |
JP2015134949A (ja) * | 2014-01-17 | 2015-07-27 | Jfe条鋼株式会社 | 肌焼鋼および機械構造用部品 |
JP2021154387A (ja) * | 2020-03-25 | 2021-10-07 | 愛知製鋼株式会社 | 浸炭用鍛造材の製造方法 |
Also Published As
Publication number | Publication date |
---|---|
JP7188432B2 (ja) | 2022-12-13 |
CN116457118A (zh) | 2023-07-18 |
JP2022098655A (ja) | 2022-07-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5123335B2 (ja) | クランクシャフトおよびその製造方法 | |
JP5862802B2 (ja) | 浸炭用鋼 | |
JP4581966B2 (ja) | 高周波焼入れ用鋼材 | |
KR20120096111A (ko) | 켄칭용 강재 및 그 제조 방법 | |
JP2003129190A (ja) | マルテンサイト系ステンレス鋼およびその製造方法 | |
JP5541418B2 (ja) | ばね鋼およびばね | |
JP4464862B2 (ja) | 耐結晶粒粗大化特性と冷間加工性に優れた軟化焼鈍の省略可能な肌焼用鋼 | |
JP6794012B2 (ja) | 耐結晶粒粗大化特性、耐曲げ疲労強度および耐衝撃強度に優れた機械構造用鋼 | |
JP2010189697A (ja) | クランクシャフトおよびその製造方法 | |
JP3606024B2 (ja) | 高周波焼入部品およびその製造方法 | |
JP4448047B2 (ja) | 耐結晶粒粗大化特性と冷間加工性に優れ、軟化焼鈍の省略可能な肌焼用鋼 | |
WO2018180342A1 (ja) | シャフト部材 | |
JP6057626B2 (ja) | 熱処理変形の小さい機械構造用鋼材 | |
JP2021154387A (ja) | 浸炭用鍛造材の製造方法 | |
CN111083928B (zh) | 钢板及其制造方法 | |
JP2005281857A (ja) | ブローチ加工性に優れた窒化部品用素材及びその素材を用いた窒化部品の製造方法 | |
JP2009191322A (ja) | 浸炭部品用の耐粗粒化特性に優れたはだ焼鋼 | |
JP7188432B2 (ja) | 温間鍛造用肌焼鋼及びこれを用いて製造した鍛造粗形材 | |
CN114000059B (zh) | 热作工具钢及热作工具 | |
JP4997709B2 (ja) | ブローチ加工性に優れた窒化部品用素材及びその製造方法 | |
WO2011155605A1 (ja) | 被削性に優れた高強度鋼、およびその製造方法 | |
KR102142894B1 (ko) | 샤프트 부품 | |
US11702716B2 (en) | Case hardening steel | |
WO2012128222A1 (ja) | 熱処理変形の小さい機械構造用鋼材 | |
JPH09324848A (ja) | 浸炭歯車部品 |
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: 21909855 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 202180079319.6 Country of ref document: CN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2301003596 Country of ref document: TH |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 21909855 Country of ref document: EP Kind code of ref document: A1 |