CN107250410B - Time hardening steel and used time hardening steel component manufacturing method - Google Patents
Time hardening steel and used time hardening steel component manufacturing method Download PDFInfo
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- CN107250410B CN107250410B CN201680010678.5A CN201680010678A CN107250410B CN 107250410 B CN107250410 B CN 107250410B CN 201680010678 A CN201680010678 A CN 201680010678A CN 107250410 B CN107250410 B CN 107250410B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 236
- 239000010959 steel Substances 0.000 title claims abstract description 236
- 238000004519 manufacturing process Methods 0.000 title claims description 32
- 230000032683 aging Effects 0.000 claims abstract description 125
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 38
- 239000000203 mixture Substances 0.000 claims abstract description 21
- 239000000126 substance Substances 0.000 claims abstract description 19
- 239000012535 impurity Substances 0.000 claims abstract description 16
- 238000005242 forging Methods 0.000 claims description 52
- 238000001816 cooling Methods 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 20
- 238000003754 machining Methods 0.000 claims description 11
- 230000008569 process Effects 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 abstract description 14
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 9
- 229910052804 chromium Inorganic materials 0.000 abstract description 8
- 229910052748 manganese Inorganic materials 0.000 abstract description 8
- 229910052710 silicon Inorganic materials 0.000 abstract description 6
- 229910052719 titanium Inorganic materials 0.000 abstract description 5
- 229910052782 aluminium Inorganic materials 0.000 abstract description 4
- 229910052758 niobium Inorganic materials 0.000 abstract description 4
- 229910052717 sulfur Inorganic materials 0.000 abstract description 4
- 238000003483 aging Methods 0.000 description 145
- 230000000694 effects Effects 0.000 description 56
- 239000010813 municipal solid waste Substances 0.000 description 34
- 229910052761 rare earth metal Inorganic materials 0.000 description 25
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- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 11
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
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- 150000001875 compounds Chemical class 0.000 description 5
- 238000005098 hot rolling Methods 0.000 description 5
- 150000004767 nitrides Chemical class 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
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- 229910052802 copper Inorganic materials 0.000 description 3
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- 230000018199 S phase Effects 0.000 description 1
- 229910000754 Wrought iron Inorganic materials 0.000 description 1
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- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
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- 230000007812 deficiency Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
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Classifications
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- 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
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
-
- 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
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- 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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- 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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- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
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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
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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- 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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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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Abstract
The time hardening steel of excellent in machinability, the fatigue properties after ageing treatment, toughness and low-cycle fatigue excellent before ageing treatment is provided.A kind of time hardening steel, it is characterized in that, chemical composition are as follows: the C containing specified amount, Si, Mn, S, Cr, Al, V, Nb, Ca and REM, and by P, the content limitation of Ti and N is below the prescribed amount, surplus includes Fe and impurity, the area ratio of bainite structure is 70% or more, and, it is 0.68 or more by the F1 that C+0.3 × Mn+0.25 × Cr is indicated, it is 0.85 or less by the F2 that C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V is indicated, it is 0.00 or more by the F3 that -4.5 × C+Mn+Cr-3.5 × V is indicated, and, it is 0.012~0.08 by the F4 that 10 × Ca+REM is indicated.Furthermore indicate that the symbol of element in the formula of F1~F4 means the content in terms of quality % of the element.
Description
Technical field
The present invention relates to time hardening steel, after being processed into defined shape by machining etc.,
Implement the time hardening steel of age-hardening processing (hereinafter referred to as " ageing treatment ").Moreover, it relates to use this
The manufacturing method of the component of the time hardening steel of sample.
Background technique
From the high output of engine, to improve fuel economy as viewpoints such as the lightweights of target, to automobile, production
The demanding fatigue strength of mechanical part of industry machinery, building machinery etc..About making steel have this project of high fatigue strength,
The hardness of steel is improved by the addition of alloying element, heat treatment etc., thus, it is possible to easily realize.But it is logical first in use
The case where method that hot forging is crossed to shape, then be finish-machined to defined shape of product by machining manufactures mechanical part
Under, also require sufficient machinability.That is, machinability is required to steel, in the rank of final products in the shaping stage of mechanical part
Section requires fatigue strength to steel.
For such requirement, it is proposed that a kind of time hardening steel, wherein in shaping stage can inhibit hardness
To be lower, then implement ageing treatment, can be improved hardness (referring for example to International Publication No. 2010/ in the final product stage
No. 090238 (patent document 1), Japanese Unexamined Patent Publication 2012-246527 bulletin (patent document 2), Japanese Unexamined Patent Publication 2011-241441
Number bulletin (patent document 3), Japanese Unexamined Patent Publication 2012-193416 bulletin (patent document 4) and Japanese Patent No. 5343923
Bulletin (patent document 5)).
Patent document 1 and 2 discloses a kind of manufacturing method, wherein by the cooling velocity after control hot forging forming, inhibits
The generation of tissue other than bainite inhibits the amount of precipitation of the VC in cooling, it is ensured that solid solution V amount, thus, it is possible to obtain adequately
Age hardening capability.But the manufacturing method that patent document 1 and 2 is recorded, when cooling process after hot forging, need to each spy
Fixed temperature region controls cooling velocity, and there are the restrictions of unit etc., furthermore also sometimes cannot on actual production line
Chilling is enough carried out, therefore, it is difficult to steadily manufacture age hardening steel.
Then, in patent document 3~5, it is proposed that not needing to be set as stringent in the cooling process after hot forging
Condition is able to carry out the time hardening steel of material of the cooling realized by air-cooled and air-supply come the mechanical part manufactured.
Summary of the invention
As described previously for the steel of the materials'use as mechanical part, it is desirable that in the fabrication stage of mechanical part, it is cut
Cutting property is excellent, and its fatigue strength is excellent after the completion of mechanical part.It is manufactured using the manufacturing method for including ageing treatment
In the case where mechanical part, above-mentioned requirements can by using have the hardness before ageing treatment it is low, after ageing treatment hardness
The steel of the characteristic of raising reaches.Productivity and all excellent mechanical part of fatigue strength in order to obtain, preferably before ageing treatment
Hardness and ageing treatment after hardness difference it is big (that is, age hardening capability is high).
But it is in the prior art for obtaining the manufacturing method of time hardening steel, it needs to include carrying out chilling to steel
Process.The quenching process can be such that the manufacturing cost of time hardening steel increases.
Additionally, it is known that keeping the toughness for dispersing steel of the fine precipitate to improve intensity in steel big by ageing treatment
Big deterioration.In the case where the toughness of steel deteriorates, the notch sensitivity of steel is improved, thus due to some steel produce
When surface defect, the low-cycle fatigue strength reduction of steel.Low-cycle fatigue intensity is to load imagination more than Hookean region
The characteristic that the steel of stress requires.The manufacturing method of time hardening steel disclosed in patent document 3~5 does not need to increase hot forging
Cooling velocity afterwards has the effect of that manufacturing cost is inhibited to increase, but is difficult to obtain the enough steel of toughness after ageing treatment.
The present invention is in view of such actual situation to complete, and project, which is to provide, does not limit manufacturing condition especially
Fixed, the excellent in machinability before ageing treatment can be such that fatigue strength steadily improves, and can press down by ageing treatment hardening
Make the time hardening steel that the toughness as caused by ageing treatment reduces.
In order to ensure sufficient hardness, fatigue strength and the low-cycle fatigue intensity after ageing treatment, need according to precipitation
The production quantity of the compounds such as carbide and carbonitride that the type suitable control of object is precipitated by ageing treatment.
Here, the present inventor is conceived to item described below.V is dissolved presence in the hot forging carried out with general temperature
Yu Gangzhong.The reason is that since the generation start temperature (Precipitation Temperature) of V carbide or V carbonitride is low.On the other hand, V
The generative capacity of precipitate (V carbide or V carbonitride) in ageing treatment is strong, therefore is effective to ageing treatment hardening
Element.But if N content is more, when cooling after hot forging and before ageing treatment, can generate V nitride, thus in timeliness
Hardness is promoted before handling, and damages machinability.The present inventor is based on these opinions, V carbide or V carbon after having attempted ageing treatment
The inhibition of the promotion of the generation of nitride and the generation of the V nitride before ageing treatment.
In addition, Ti in conjunction with N, C, forms coarse Ti carbonitride, even if content is the micro of 0.005% degree,
Toughness can be made to deteriorate significantly.Then, the present inventor is based on these opinions, has attempted the Ti content for reducing steel.
In addition, heating of the Nb in hot forging, being precipitated in steel as carbide or carbonitride in process, have
The effect for making austenite matrix partial size miniaturize, miniaturize bainite structure in bainitic transformation behind by pinning effect
Fruit.Moreover, a part of Nb in steel exists in hot forging not as carbide or Carbonitride Precipitation, but as Nb is dissolved.
Solid solution Nb is by that, as Nb carbide or Nb Carbonitride Precipitation, will not incur toughness reduction when ageing treatment after hot forging
And hardness is improved, thus have the effect of realizing the raising of low-cycle fatigue intensity and fatigue strength.The present inventor is based on this
A little opinions have been attempted to inhibit the reduction of the toughness as caused by ageing treatment using Nb.
Moreover, in order to improve fatigue strength steadily, and keep the toughness after ageing treatment also stable without reducing, no
The type and production quantity of the precipitates such as the carbide and carbonitride that only need suitable control to be precipitated by ageing treatment, also need
The form for the field trash for wanting suitable control to be present in steel.
Then, the present inventor is conceived to item described below.REM is that have by forming sulfide-based field trash or oxygen
Compound system field trash makes field trash fine dispersion and makes element of the inclusion morphology as spherical effect.But if
REM content is excessive, then the high-temperature ductility of steel when hot rolling or hot forging can be made to reduce.The present inventor is based on the opinion, seeks REM
Suitableization of content, exploring and having determined can be such that fatigue strength steadily improves by ageing treatment hardening, and in timeliness
Stablize toughness without reduced condition.
The present invention is completed based on such opinion, and main idea is as follows.
[1] a kind of time hardening steel, which is characterized in that chemical composition are as follows: in terms of quality %, containing C:0.05~
0.20%, Si:0.01~0.50%, Mn:1.50~2.50%, S:0.005~0.080%, Cr:0.03~1.60%, Al:
0.005~0.050%, V:0.25~0.50%, Nb:0.010~0.100%, Ca:0.0005~0.0050%, REM:0.001
~0.05%, also, P is restricted to 0.030% hereinafter, Ti is limited to less than 0.005%, N is limited to less than
0.0080%, surplus includes Fe and impurity, and the area ratio of bainite structure is 70% or more, moreover, following indicated by formula (1)
F1 be 0.68 or more, be 0.85 hereinafter, being 0.00 or more by the F3 of formula (3) expression, also, by formula by the F2 that formula (2) indicate
(4) F4 indicated is 0.012~0.08,
F1=C+0.3 × Mn+0.25 × Cr (1)
F2=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V (2)
F3=-4.5 × C+Mn+Cr-3.5 × V (3)
F4=10 × Ca+REM (4)
The symbol of element in above-mentioned formula (1)~(4) means the content in terms of quality % of the element.
[2] a kind of time hardening steel, which is characterized in that chemical composition are as follows: in terms of quality %, containing C:0.05~
0.20%, Si:0.01~0.50%, Mn:1.50~2.50%, S:0.005~0.080%, Cr:0.03~1.60%, Al:
0.005~0.050%, V:0.25~0.50%, Nb:0.010~0.100%, Ca:0.0005~0.0050%, REM:0.001
~0.05%, moreover, meet any of composition condition shown in following < a >~< c > or more,
< a > Mo:0.01~1.0%,
A side or two sides in < b > Cu:0.01~0.30% and Ni:0.01%~0.30%,
< c > Bi:0.01~0.400%,
Also, P is restricted to 0.030% hereinafter, Ti is limited to less than 0.005%, N is limited to less than
0.0080%, surplus includes Fe and impurity, the area ratio of bainite structure is 70% or more, following to be indicated by formula (1 ')
F1 ' is 0.68 or more, is 0.85 hereinafter, being 0.00 or more by the F3 ' that formula (3 ') indicate by the F2 ' that formula (2 ') indicate, also, by
The F4 that formula (4) indicates is 0.012~0.08,
F1 '=C+0.3 × Mn+0.25 × Cr+0.6 × Mo (1 ')
F2 '=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V+0.2 × Mo (2 ')
F3 '=- 4.5 × C+Mn+Cr-3.5 × V-0.8 × Mo (3 ')
F4=10 × Ca+REM (4)
The symbol of element in above-mentioned formula (1 ')~(3 ') and (4) means the content in terms of quality % of the element.
[3] a kind of manufacturing method for the component for having used time hardening steel characterized by comprising forging process, it will
Time hardening steel described in above-mentioned [1] or [2] heats 5~60 minutes at 1200~1250 DEG C, then so that after finish forge
Surface temperature is that 1100 DEG C or more of mode is forged, then, by the average cooling rate of 800~400 DEG C of temperature region
15~60 DEG C/min are set as to be cooled to room temperature；Machining process carries out machining to the steel after forging；At timeliness
Science and engineering sequence, the temperature region by the steel after machining at 540~700 DEG C are kept for 30~1000 minutes.
In accordance with the invention it is possible to provide a kind of time hardening steel, wherein manufacturing condition is not particularly limited, timeliness
Excellent in machinability before processing, by ageing treatment hardening fatigue strength can be made steadily to improve, further, it is possible to inhibit by when
Toughness caused by effect is handled reduces.In addition, being capable of providing productivity as material by using time hardening steel of the invention
Excellent, fatigue strength is excellent and the enough mechanical parts of toughness.
Furthermore time hardening steel of the invention, as the Vickers hardness before the ageing treatment of the index of cutting resistance
For 290Hv or less.It is the generally cylindrical shaped of 35mm that diameter, which is made, in time hardening steel of the invention, and by the temperature of the steel
Kept for carry out ageing treatment within 120 minutes at 620 DEG C, the ascending amount (age-hardening of the Vickers hardness as caused by the ageing treatment
Ability, Δ Hv)) it is 30Hv or more.The fatigue strength of time hardening steel of the invention after ageing treatment is 425MPa or more.
In addition, the time hardening steel of the invention after ageing treatment, is being 2mm and notch bottom using with notch depth
Absorption in the Charpy-type test that the standard sample for the U-shaped notch that portion's radius is 1mm is implemented at 20 DEG C can be 50J or more,
Low-cycle fatigue intensity is 520MPa or more.
In this way, time hardening steel of the invention can very suitably be used as automobile, industrial machine, building machinery etc.
Mechanical part material, the contribution highly significant in industry.
Detailed description of the invention
The figure of the shape of Fig. 1 is that indicate to use in embodiment the be uniaxially stretched fatigue testing specimen of compression-type.Number in figure
Value indicates size (unit: mm).
Specific embodiment
< is so that export the opinion > of the present application
Hereinafter, from the viewpoint of age-hardening, in the chemical composition of time hardening steel of the present embodiment
Important element be illustrated.
Furthermore time hardening steel (hereinafter sometimes referred to simply as " steel of the present embodiment ") of the present embodiment
Main application, be taken as include the mechanical part of the manufacturing method manufacture of hot forging, cutting and ageing treatment etc. material.
Therefore, in order to illustrate the feature of steel of the present embodiment, reference sometimes is implemented after hot forging, cutting and ageing treatment
Steel characteristic.But steel of the present embodiment must not necessarily carry out such processing.That is, present embodiment is related to
Steel purposes be not limited to be hot-forged and cut etc..
Firstly, present inventor have discovered that needing to make 0.25 mass % of V content or more in steel of the present embodiment.
By making 0.25 mass % of V content or more, the carbon nitridation of the carbide or V of the V generated by ageing treatment can be increased
The amount of object etc., the hardness after improving ageing treatment, it is ensured that fatigue strength.
V is once solid-solution in steel, will not be precipitated before steel to be cooled to 850 DEG C nearby, in age-hardening treatment temperature
Under carbide or carbonitride generative capacity it is strong.Moreover, steel of the present embodiment, can also add in the same manner as V
The Precipitation Temperature of carbide is lower, is easily and efficiently used for the Mo of age-hardening.If making the V's containing 0.25 mass % or more
Steel also contains Mo, then will form the double carbide of V and Mo or the compound carbonitride of V and Mo by ageing treatment, because at this time
Treated that hardness further increases for effect.
It is once solid-solution in steel as described above, V has, the property that will not be precipitated before steel to be cooled to 850 DEG C nearby,
It therefore is that can make it in steel with solid solution condition steadily existing element.But V carbide in austenite to ferritic phase
It is easy to be precipitated in phase interface when change.If the amount of precipitation of V carbide increases, it is dissolved the reduction of V amount.That is, if in heat
It is generated in large quantities in cooling after forging and just analyses ferrite, then V carbide can be precipitated in phase interface, therefore can not ensure to pass through it
The solid solution V of amount needed for the precipitation-hardening that ageing treatment afterwards is realized.Therefore, for the time hardening steel before ageing treatment
Inside ensure an adequate amount of solid solution V, needs to make in the tissue after hot forging and before ageing treatment, phase that the area ratio is 70% or more (with
It is known as " main phase " down) become bainite.Also, the manufacturing cost of mechanical part is surging in order to prevent, needs such tissue control
System is not carried out by being hot-forged the control of condition, passes through carrying out at the control being grouped as steel.
Tissue after hot forging, it is closely related with the content of C, Mn and Cr and Mo for improving hardenability.Human hair of the present invention
It is existing: if becoming specific numerical value or more with the value of the index F1 and F1 ' of the hardenability indicated by following formula (1) or formula (1 ')
Mode controls the content of the element in these formulas, then the cooling procedure after common hot forging (cooling velocity be 15 DEG C/min~
60 DEG C/min) in, the ferritic a large amount of precipitations of harmful just analysis, which are inhibited, to be ensured to solid solution V.That is, of the invention
People's discovery: by controlling F1 and F1 ', structure of steel easily becomes the tissue using bainite as main phase, i.e., comprising in terms of the area ratio
For the tissue of 70% or more bainite, therefore it can ensure an adequate amount of solid solution V.
F1=C+0.3 × Mn+0.25 × Cr (1)
F1 '=C+0.3 × Mn+0.25 × Cr+0.6 × Mo (1 ')
But even if by making structure of steel become true with the tissue of bainite main phase (being calculated as 70% or more by the area ratio)
An adequate amount of solid solution V is protected, the hardness before ageing treatment (using bainite as the hardness of the tissue of main phase) is also got higher sometimes.At this
In the case of, the cutting resistance of the steel after incurring hot forging sometimes rises, and machinability reduces.Present inventors studied solve the problems, such as this
Method.As a result, present inventor have discovered that content about C, Si, Mn, Cr, V and Mo, if with by following formulas (2) or formula
(2 ') value of the index F2 and F2 ' of the hardness before the ageing treatment indicated control this implementation as specific numerical value mode below
The chemical component for the steel that mode is related to can then ensure that the hardness before ageing treatment is lower, is able to suppress the rising of cutting resistance.
F2=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V (2)
F2 '=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V+0.2 × Mo (2 ')
In addition, the present inventor has manufactured following steel, the steel contains the V of 0.25 mass % or more, and about C, Si,
The content of Mn, Cr, Mo and V have carried out composition adjustment so that by above-mentioned formula (1) and formula (2) or formula (1 ') and formula (2 ')
The F1 and F2 or F1 ' and F2 ' found out meets specific numberical range, will implement ageing treatment after steel hot forging, examination is then made
Sample investigates the toughness of the sample.Specifically, being made and having after carrying out hot forging and ageing treatment to above-mentioned steel
The standard sample for the U-shaped notch that notch depth is 2mm and kerf bottom radius is 1mm implements Charpy impact, investigation to the sample
Ingredient is to timeliness treated influence that toughness gives.
The result of above-mentioned investigation is carried out it is found that being able to suppress the reduction of the toughness as caused by ageing treatment in order to obtain
Steel needs to control the content of C, Mn, Cr, V and Mo of steel so that after by following formulas (3) or the ageing treatment of formula (3 ') expression
The value of index F3 and F3 ' of toughness become specific value or more.
F3=-4.5 × C+Mn+Cr-3.5 × V (3)
F3 '=- 4.5 × C+Mn+Cr-3.5 × V-0.8 × Mo (3 ')
In F3 and F3 ' it is big in the case where, deficiency will not occur for the toughness of the steel after ageing treatment.In addition, C, V and Mo's contains
The increase of amount can make F3 and F3 ' it reduces.Therefore, formula (3) or formula (3 ') mean to inhibit the toughness as caused by ageing treatment
It reduces, it is desirable to reduce be the content of C, V and Mo needed for hardness and the fatigue strength after improving ageing treatment.
In turn, it in order to have both intensity and toughness, needs to efficiently use the element other than C, V, Mo, improves ageing treatment
Hardness afterwards, seeks intensity to improve.
In order to inhibit the toughness after ageing treatment to reduce, the miniaturization of tissue is effective.In order to which the shellfish of main phase will be used as
Family name's body tissue is miniaturize, and the miniaturization of the austenite partial size before bainitic transformation is effective.It is fine for austenite partial size
Change, it is effective for so that steel is contained Ti, but cannot use the means in steel of the present embodiment.Present inventor have discovered that
Ti will form the coarse Ti carbonitride for deteriorating the toughness of steel of the present embodiment, therefore even if Ti content is
0.005% degree it is micro, Ti also can be such that the toughness of the steel after ageing treatment deteriorates significantly.Therefore, of the present embodiment
The content of Ti in steel needs to be limited to zero or specific value or less as far as possible.
In addition, cannot be accessed adequately tough if there is the field trash for causing harmful influence on toughness in steel
Property.Need to make the content of S to become specific value or less to the harmful field trash of toughness to inhibit to exist in steel.In addition, S
It is the element for deteriorating toughness, it is therefore necessary to avoid being excessively added for S by conjunction with Mn, forming coarse MnS.Another party
Face, MnS are in order to ensure field trash necessary to sufficient machinability.Therefore, the content for preferably not making S is entirely zero.For
The machinability of steel before improving ageing treatment, and the toughness of the steel as caused by ageing treatment is inhibited to reduce, it needs suitably to control
The content of S processed, it is excessive to avoid the amount of MnS.
Present inventor have discovered that strong as the low-cycle fatigue after the machinability and ageing treatment before abundant raising ageing treatment
The means spent and the toughness as caused by ageing treatment is inhibited to reduce, are effective containing Nb.Nb has in the same manner as Ti by shellfish
The effect of the austenite partial size miniaturization of family name's body before phase change.
Nb is that have the effect of for austenite partial size miniaturizeing, and also have the compound (2 under aging temperature
Secondary phase) generative capacity element.The reason is that Nb Precipitation Temperature compared with V and Mo is high.That is, due to the Precipitation Temperature of Nb
A part of higher therefore contained Nb is precipitated in hot forging as carbide or carbonitride etc., the Nb of the carbide etc.
Precipitate facilitates the miniaturization of austenite partial size.
In the steel for meeting the condition that above-mentioned formula (1) or formula (1 ') become specific range, there are solid solution Nb.This is because
The main phase for meeting the steel of formula (1) or formula (1 ') as described above is bainite structure, and Nb is easy to be solid-solution in the edge in bainite structure
Therefore.Therefore, the steel for becoming specific range for formula (1) or formula (1 '), can make Nb carbide or Nb carbon by ageing treatment
Nitride is precipitated.In addition, the inventors discovered that following characteristics: toughness will not be caused to drop these Nb system precipitates are precipitated
It is low, the hardness of the steel after can be improved ageing treatment.Moreover, the present inventors have additionally discovered that: by containing Nb, can be realized can pass through
The miniaturization and precipitation strength of bainite structure and obtain the steel of excellent low-cycle fatigue intensity.
As described above, the present inventor has obtained about being not particularly limited cutting before the manufacturing condition of Steel material, ageing treatment
The reduced timeliness that cutting property is excellent, can improve fatigue strength by ageing treatment hardening, inhibit the toughness after ageing treatment
The opinion of hardenability steel.But only with above-mentioned opinion, although intensity, toughness after ageing treatment is in the range of desired value
It is interior, but it is sometimes slightly lower.
Therefore, the mechanism that the present inventor conscientiously has studied the fatigue strength after ageing treatment, toughness is lower, as a result, it has been found that being
The coarse field trash as present in steel.That is, specifying: the generation by inhibiting the coarse field trash can be mentioned steadily
Fatigue strength after high ageing treatment, and it is able to suppress the reduction of the toughness after ageing treatment.
In order to inhibit coarse field trash, the present inventor is conceived to REM.REM, which has, forms sulfide-based field trash or oxidation
Object system field trash makes the effect of sulfide-based field trash, oxide system field trash all fine dispersions.But if REM content mistake
It is more, then the high-temperature ductility of steel when hot rolling or hot forging can be made to reduce.
But when only adjusting REM content, sulfide-based field trash, oxide system field trash can not be made all steadily
Fine dispersion.Present inventors understand that arriving: about REM and Ca, needing to control the content of Ca, REM so that by following formula (4) tables
The value of the Con trolling index F4 of the inclusion morphology shown becomes specific range.Present inventor have discovered that by doing so, sulfide-based
Field trash is with spherical fine dispersion, and oxide system field trash also fine dispersion.
F4=10 × Ca+REM (4)
When F4 is 0.012 or more, sulfide-based field trash, oxide system field trash all steadily fine dispersions.In addition, such as
Fruit F4 is more than 0.08 its effect saturation, it is possible to which making the high-temperature ductility of steel reduces, it is therefore desirable to seek the conjunction of Ca, REM content
Suitableization.
Realized the present invention relates to result of study and obtained opinion based on present invention mentioned above people when
Imitate hardenability steel.
Hereinafter, each necessary condition of the time hardening steel of one embodiment of the present invention is described in detail.
< is at being grouped as >
Firstly, being illustrated to the ingredient of time hardening steel of the present embodiment.Furthermore the content of each element
" % " means " quality % ".
(indispensable element)
C:0.05~0.20%
C is element important in the present embodiment.C forms carbide by ageing treatment in conjunction with V, and steel is strengthened.
But if the content of C becomes smaller less than the precipitation driving force of 0.05%, V carbide, it is difficult to V carbide be precipitated, therefore obtain not
To desired strengthening effect.On the other hand, if the content of C is more than 0.20%, the C not in conjunction with V can in conjunction with Fe shape
At carbide (cementite), the toughness of steel can be made significantly to deteriorate.In addition, in the case where the content of C is more than 0.20%, from Austria
Into the way of bainitic transformation, C concentration of denseization in austenite is also got higher family name's body, in the middle part of the tissue after making bainitic transformation
It is mixed into martensite with dividing.In this way, cutting resistance rises in the case where including cementite and/or martensite in steel, machinability drop
It is low.Therefore, the content of C is set as 0.05~0.20%.The content of C is preferably 0.08% or more, and more preferably 0.10% or more.
In addition, the content of C is preferably 0.18% hereinafter, more preferably 0.16% or less.
Si:0.01~0.50%
Deoxidant element when Si is as steel processed is useful, meanwhile, have and is solid-solution in matrix and improves the intensity of steel
Effect.In order to sufficiently obtain these effects, Si needs to be set as 0.01% or more content.But if the content of Si is excessive,
The reduction of the hot-workability of steel and the rising of cutting resistance can then occur, machinability is caused to reduce.Especially if Si content is super
0.50% is crossed, then the reduction of the hot-workability of steel and the rising of cutting resistance become significant.Moreover, Si is possible to promote just to analyse iron
The generation of ferritic does not preferably contain Si excessively to make the bayesian scale of construction reduce, therefore in order to stably obtain bainite.Again
Person, in the case where the fabrication stage of steel produces the just ferritic situation of analysis, as described above, V carbide is in just analysis ferrite and Ovshinsky
The phase interface of body is precipitated, it is difficult to ensure solid solution V needed for the precipitation-hardening generated as ageing treatment, result is there is a possibility that steel
Age hardening capability reduces.Therefore, the content of Si is set as 0.01~0.50%.The content of Si is preferably 0.06% or more.Separately
Outside, the content of Si is preferably 0.45% hereinafter, more preferably less than 0.35%.
Mn:1.50~2.50%
Mn, which has, improves hardenability, and the main phase of tissue is made to become the effect of bainite.Moreover, Mn, which has, makes bainitic transformation
The effect that temperature reduces, thus, it may have miniaturize tissue, improve the effect of the toughness of matrix.Furthermore steel body product will be occupied
Most tissue be known as matrix, the matrix of steel of the present embodiment is bainite.It is formed in steel in addition, Mn has
MnS and reduce cutting resistance, thus make machinability improve effect.In addition, having can in the case where Mn amount is less than 1.50%
It can promote the just ferritic generation of analysis, to cause the reduction of the bayesian scale of construction and the reduction of age hardening capability as described above.
In order to sufficiently obtain these effects, Mn needs to be set as at least 1.50% content.But Mn is to be easy segregation in steel solidification
Element, so if can not then avoid the hardness in the component after being hot-forged containing quantitative change mostly, particularly more than 2.50%
It fluctuates (unevenness).Therefore, the content of Mn is set as 1.50~2.50%.The content of Mn is preferably 1.60% or more, more preferably
1.70% or more.In addition, the content of Mn is preferably 2.30% hereinafter, more preferably 2.10% or less.
S:0.005~0.080%
S forms MnS in steel in conjunction with Mn, reduces cutting resistance, improves machinability.Adequately cutting in order to obtain
Property, need the S containing 0.005% or more.But if the content of S is excessively high, coarse MnS increases, it is possible to make toughness
It is deteriorated with fatigue strength.Especially if the content of S is more than 0.080%, then the reduction of toughness and fatigue strength becomes significant.Cause
This, is set as 0.005~0.080% for the content of S.The content of S is preferably 0.010% or more.In addition, the content of S is preferably
0.050% hereinafter, further preferably 0.030% or less.
Cr:0.03~1.60%
Cr, which has, improves hardenability, and the main phase of tissue is made to become the effect of bainite.Moreover, Cr, which has, makes bainitic transformation
The effect that temperature reduces, thus, it may have make the effect of tissue imperceptibility, the toughness for improving matrix.But the if content of Cr
More than 1.60%, then hardenability is excessive, and according to the size of component, position, hardness before ageing treatment is with Vickers hardness in respect of can
It can exceed that 290Hv, therefore cutting resistance rises sometimes, machinability reduces.Therefore, the content of Cr is set as 0.03~1.60%.
The lower limit of the content of Cr is preferably 0.05% or more, and more preferably 0.10% or more.The upper limit of the content of Cr is preferably 1.00%
Hereinafter, more preferably 0.50% or less.
Al:0.005~0.050%
Al is the element with deoxidation, in order to play the content that the effect needs 0.005% or more.But if
The content of Al is more than 0.050%, then can generate coarse oxide, and the toughness and fatigue strength of steel reduce.Therefore, containing Al
Amount is set as 0.005~0.050%.The content of Al is preferably 0.040% or less.
V:0.25~0.50%
V is the most important element in steel of the present embodiment.V has the effect that by ageing treatment
Fine V carbide is formed in conjunction with C, alternatively, by forming fine V carbonitride in conjunction with C and N, to improve at timeliness
The intensity of steel after reason.It is precipitated compoundly in addition, V also has by ageing treatment and Mo, further increases the age-hardening of steel
The effect of ability.Sufficiently to obtain these effects, V content needs to be 0.25% or more.But if the content of V is excessive, i.e.,
Make also to be easy the carbonitride that residual is not dissolved in the heating in hot forging, leads to the reduction of toughness, especially if its content
More than 0.50%, then the reduction of toughness becomes significant.Moreover, if the content of V is more than 0.50%, sometimes with not being dissolved carbon
The residual of compound, cutting resistance rise, and the machinability of steel is significantly reduced.Therefore, the content of V is set as 0.25~0.50%.V
Content be preferably less than 0.45%, more preferably 0.40% or less.In addition, the content of V is preferably 0.27% or more.
Nb:0.010~0.100%
Nb is one of the important element in steel of the present embodiment.A part of Nb contained in steel is in hot forging
Heating, be precipitated in steel as Nb carbide or Nb carbonitride in process, austenite grain is made by pinning effect
The miniaturization of austenite grain when the hot-working of miniaturization, having in bainitic transformation after hot-working makes bainite
Organize the effect of miniaturization.Moreover, hot forging when steel in Nb a part as solid solution Nb exist, Nb is after hot forging for the solid solution
Ageing treatment when as Nb carbide or Nb Carbonitride Precipitation, thus have and not will lead to toughness reduction, improve hardness, it is real
The effect of the raising of the raising and fatigue strength of existing low-cycle fatigue intensity.Sufficiently to obtain these effects, Nb content needs are
0.010% or more.But if the content of Nb is excessive, the carbon that residual is not dissolved is easy in the heating in hot forging
Nitride, the effect of the hardness after improving ageing treatment and/or the effect saturation for improving the fatigue strength after ageing treatment.And
And if the content of Nb is more than 0.100%, sometimes with the residual of the carbide or carbonitride that are not dissolved, cutting resistance
Rise, the machinability of steel significantly reduces.Therefore, the content of Nb is set as 0.010~0.100%.The content of Nb is preferably less than
0.080%, more preferably 0.050% or less.In addition, the content of Nb is preferably 0.020% or more.
Ca:0.0005~0.0050%
Ca is one of the important element in steel of the present embodiment.Ca contained in steel, by as sulfide
It is that field trash or oxide system field trash are imperceptibly dispersed to precipitate in steel, there is the fatigue strength after improving ageing treatment, suppression
The effect that toughness after ageing treatment processed reduces.Sufficiently to obtain the effect, Ca content needs to be 0.0005% or more.But
If the content of Ca is more than 0.0050%, it will form coarse oxide system field trash instead, make high-temperature ductility, ageing treatment
Fatigue strength afterwards reduces, the effect that the toughness after cannot inhibiting ageing treatment reduces.Therefore, the content of Ca is set as
0.0005~0.0050%.Furthermore the content of Ca is preferably 0.0010% or more, and more preferably 0.0015% or more.
REM:0.001~0.05%
REM is one of the important element in steel of the present embodiment.REM contained in steel, by as sulfide
It is that field trash or oxide system field trash are imperceptibly dispersed to precipitate in steel, there is the fatigue strength after improving ageing treatment, and
The effect that toughness after inhibiting ageing treatment reduces.Sufficiently to obtain the effect, REM content needs to be 0.001% or more.But
It is, if the content of REM is more than 0.05%, to lead to the reduction of high-temperature ductility.Therefore, the content of REM is set as 0.001~
0.05%.The content of REM is preferably 0.003% or more, and more preferably 0.005% or more.
The time hardening steel of present embodiment, chemical composition are as follows: comprising above-mentioned C, Si, Mn, S, Cr, Al, V,
Nb, Ca, REM, surplus include Fe and impurity, P, Ti and N in aftermentioned impurity be restricted to P:0.030% or less, Ti: less than
0.005%, N: less than 0.0080% is in turn 0.68 or more by the F1 that above-mentioned formula (1) indicates, is by the F2 that formula (2) indicate
0.85 hereinafter, be 0.00 or more by the F3 that formula (3) indicate, also, be 0.012 or more and 0.08 or less by the F4 that formula (4) indicate.
Furthermore so-called impurity refers to when industrially manufacturing steel material, from as the ore of raw material, waste material or from manufacture
The mixed substance such as environment.
P:0.030% or less
P contains as impurity, is undesirable element in steel of the present embodiment.That is, P cyrystal boundary segregation from
And toughness is reduced, especially if its content is more than 0.030%, then the reduction of toughness becomes highly significant.Therefore, by P's
Content is limited to 0.030% or less.It is preferred that the content of P is limited to 0.025% or less.
Furthermore the content lower limit of special provision P can not play the effect of steel of the present embodiment.P content
Lower limit value also can be set to 0%.But will lead to the extreme rising of de- P cost if excessively reducing P, economic aspect not
Benefit, therefore the lower limit of P amount is preferably set as 0.005%.
Ti: less than 0.005%
Ti contains as impurity, is undesirable element in steel of the present embodiment.That is, Ti is in conjunction with N, C
Coarse Ti carbonitride is formed, the reduction of toughness is caused, especially if its content is 0.005% or more, then can make toughness
It deteriorates significantly.Therefore, the content of Ti is limited to less than 0.005%.In order to inhibit the reduction of the toughness as caused by ageing treatment, Ti
Content be preferably limited to 0.0035% hereinafter, being further preferably limited to 0.0015% or less.The lower limit value of Ti content can also
To be set as 0%.
N: less than 0.0080%
N contains as impurity, in steel of the present embodiment, be can by V in the form of VN it is fixed not preferably
Element.That is, being helpless to age-hardening, therefore the precipitation in order to inhibit VN as the VN V being precipitated, it is necessary to reduce the content of N.For
Inhibit the precipitation of VN, the stage before ageing treatment ensures an adequate amount of solid solution V, needs for the content of N to be limited to less than
0.0080%.The upper limit value of N content is preferably 0.0070%, 0.0060% or 0.0050%.The lower limit value of N content is 0%.
Another embodiment of time hardening steel of the present embodiment, chemical composition are as follows: comprising above-mentioned from C
To the element of REM, composition meets either one or two of above-mentioned < a >~< c > or more, and surplus includes Fe and impurity, P, Ti in impurity
P:0.03% or less, Ti: less than 0.005%, N:0.020% are restricted to hereinafter, moreover, above-mentioned indicated by formula (1 ') with N
F1 ' be 0.68 or more, by formula (2 ') indicate F2 ' be 0.85 hereinafter, by formula (3 ') expression F3 ' be 0.00 or more, also,
It is 0.012 or more and 0.08 or less by the F4 that formula (4) indicate.
(optional element)
Hereinafter, to selectively adding in another embodiment of time hardening steel of the present embodiment
The function and effect of arbitrary element shown in < a >~< c > and its restriction reason of content are illustrated.
< a > Mo:0.01~1.0%
Due to must not necessarily contain Mo, the lower limit value of Mo content is 0%.On the other hand, Mo have improve hardenability,
The main phase of the tissue of steel after making hot forging becomes bainite and increases the effect of the area ratio of bainite.Mo is containing
In the steel of 0.25% or more V, it may have with V-arrangement at carbide, increase the effect of the age hardening capability of steel.Therefore, may be used
To contain Mo as needed.But Mo is the very high element of price, so if the manufacturing cost of more then steel containing quantitative change increases
Greatly, and toughness also reduces.Therefore, in the case of containing, the amount of Mo is set as 1.0% or less.In the case of containing, Mo
Amount be preferably 0.50% hereinafter, more preferably 0.40% hereinafter, further preferably less than 0.30%.
On the other hand, in order to stably obtain the effect of above-mentioned Mo, in the case of containing, the amount of Mo is preferably
0.01% or more, more preferably 0.05% or more, further preferably 0.10% or more.
A side or two sides in < b > Cu:0.01~0.30% and Ni:0.01~0.30%
Cu and Ni has the function of improving the fatigue strength of the steel after ageing treatment.Therefore, expect it is bigger tired
In the case where labor intensity, these elements can be contained in following ranges.
Cu:0.01~0.30%
Due to must not necessarily contain Cu, the lower limit value of Cu content is 0%.On the other hand, Cu, which has, improves at timeliness
The effect of the fatigue strength of steel after reason.Therefore, it can according to need containing Cu.But if the content of Cu is more than 0.30%,
Then hot-workability reduces.Therefore, in the case of containing, the amount of Cu is set as 0.30% or less.In the case of containing, Cu
Amount preferably 0.25% or less.
On the other hand, in order to stably obtain above-mentioned Cu raising fatigue strength effect, in the case of containing, Cu
Amount be preferably 0.01% or more, more preferably 0.05% or more, further preferably 0.10% or more.
Ni:0.01~0.3%
Due to must not necessarily contain Ni, the lower limit value of Ni content is 0%.On the other hand, Ni, which has, improves at timeliness
The effect of the fatigue strength of steel after reason.Moreover, Ni also has the function of inhibiting the reduction of the hot-workability as caused by Cu.Cause
This, can according to need containing Ni.But if the content of Ni is more than 0.30%, other than cost increases, said effect
Also it is saturated.Therefore, in the case of containing, the amount of Ni is set as 0.30% or less.In the case of containing, the amount of Ni is preferably
0.25% or less.
On the other hand, in order to stably obtain the effect of above-mentioned Ni, in the case of containing, the amount of Ni is preferably
0.01% or more, more preferably 0.05% or more, further preferably 0.10% or more.
Furthermore about above-mentioned Cu and Ni, can only containing therein any, alternatively, can also it is compound containing this two
Kind element.In the case of containing, it is respective upper limit value that total content of above-mentioned element, which is also possible to the content of Cu and Ni,
In the case of 0.6%.
< c > Bi:0.01~0.400%
Bi has the function of reducing the cutting resistance of the steel before ageing treatment, improves machinability.Therefore, wanting to obtain more
In the case where good machinability, Bi can be contained in following ranges.
Due to must not necessarily contain Bi, the lower limit value of Bi content is 0%.On the other hand, Bi, which has, reduces at timeliness
The effect of the cutting resistance of steel before reason and the effect for improving chip treatability.Therefore, it can according to need to contain Bi.But
It is that, if the content of Bi is more than 0.400%, the reduction of hot-workability can be brought.Therefore, in the case of containing, by Bi's
Amount is set as 0.400% or less.In the case of containing, the amount of Bi is preferably 0.300% or less.
On the other hand, in order to stably obtain above-mentioned Bi reduction cutting resistance effect and improve chip treatability
Effect, in the case of containing, the amount of Bi are preferably 0.010% or more, and more preferably 0.030% or more.
In above-mentioned present embodiment and another embodiment, for Fe and not in remaining quality entity other than above-mentioned element
Evitable impurity, but other elements can be added microly in the range of not damaging function and effect of the invention.
< formula (1)~formula (4) and formula (1 ')~formula (3 ') >
Then, it is indicated for the above-mentioned F1~F4 indicated by formula (1)~formula (4) and by formula (1 ')~formula (3 ')
F1 '~F3 ' is illustrated.
(F1 or F1 ': 0.68 or more)
Time hardening steel of the present embodiment, in the case where being free of the Mo, by
F1=C+0.3 × Mn+0.25 × Cr (1)
The F1 of expression is necessary for 0.68 or more.
On the other hand, time hardening steel of the present embodiment, in the case where containing the Mo, by
F1 '=C+0.3 × Mn+0.25 × Cr+0.6 × Mo (1 ')
The F1 ' of expression is necessary for 0.68 or more.
As has been described, the symbol of element in above-mentioned formula (1) and formula (1 ') mean the element in terms of quality %
Content.
F1 and F1 ' is the index for hardenability.If the amount of each alloying element contained in steel meet above-mentioned range,
And F1 and F1 ' meet above-mentioned condition, and even if there is no then the acceleration for carrying out water cooling etc. cooling after hot forging, the tissue after hot forging
It can become using bainite as the tissue of main phase.
In the case where F1 or F1 ' is less than 0.68, it is mixed into the tissue after hot forging and just analyses ferrite, V carbide is in phase boundary
Face is precipitated, therefore the hardness before ageing treatment rises, and age hardening capability becomes smaller.
F1 and F1 ' is preferably 0.70 or more, and more preferably 0.72 or more.On the other hand, due to the excessive increase of hardenability
The toughness for being likely to result in steel reduces, therefore F1 and F1 ' are preferably 1.00 hereinafter, more preferably 0.98 or less.
(F2 ': 0.85 or less F2 or)
Time hardening steel of the present embodiment, in the case where being free of the Mo, by
F2=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V (2)
The F2 of expression is necessary for 0.85 or less.
On the other hand, time hardening steel of the present embodiment, in the case where containing the Mo, by
F2 '=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V+0.2 × Mo (2 ')
The F2 ' of expression is necessary for 0.85 or less.
As has been described, the symbol of element in above-mentioned formula (2) and formula (2 ') mean the element in terms of quality %
Content.
F2 and F2 ' is the index of the hardness before indicating ageing treatment.Even if steel meets the condition of above-mentioned F1 or F1 ', such as
Fruit F2 or F2 ' be not in appropriate range, then the excessive high hardness before ageing treatment, cutting resistance rise, can not ensure sometimes
Good machinability.
That is, if F2 or F2 ' more than 0.85, the excessive high hardness of bainite structure.Therefore, the rising of cutting resistance sometimes
Unavoidably, it can not ensure good machinability.
F2 and F2 ' is preferably 0.82 hereinafter, more preferably 0.80 or less.On the other hand, in F2 and F2 ' too low situation
Under, the hardness after age-hardening is possible to insufficient, therefore F2 and F2 ' they are preferably 0.55 or more, and more preferably 0.60 or more.
(F3 or F3 ': 0.00 or more)
Time hardening steel of the present embodiment, in the case where being free of the Mo, by
F3=-4.5 × C+Mn+Cr-3.5 × V (3)
The F3 of expression is necessary for 0.00 or more.
On the other hand, time hardening steel of the present embodiment, in the case where containing the Mo, by
F3 '=- 4.5 × C+Mn+Cr-3.5 × V-0.8 × Mo (3 ')
The F3 ' of expression is necessary for 0.00 or more.
As has been described, the symbol of element in above-mentioned formula (3) and formula (3 ') mean the element in terms of quality %
Content.
F3 and F3 ' is the index of the toughness after indicating ageing treatment.That is, even if meeting F1 or F1 ' and F2 or F2 '
Condition can not ensure mesh if F3 or F3 ', not in appropriate range, the toughness of the steel after ageing treatment reduces sometimes
Mark toughness.
That is, the toughness after ageing treatment reduces in the case where F3 or F3 ' is less than 0.00 (for negative).
F3 and F3 ' is preferably 0.01 or more.
Furthermore if F1 be 0.68 or more and F2 be 0.85 hereinafter, if do not need that the upper limit of F3 is particularly limited.
Similarly, if F1 ' be 0.68 or more and F2 ' be 0.85 hereinafter, if do not need to carry out the upper limit of F3 ' it is special
It limits.
(F4:0.012~0.08)
Time hardening steel of the present embodiment, by
F4=10 × Ca+REM (4)
The F4 of expression is necessary for 0.012 or more and 0.08 or less.
As has been described, the symbol of element in above-mentioned formula (4) means the content in terms of quality % of the element.
F4 is the index for indicating the Con trolling index of inclusion morphology.That is, even if steel meet F1 or F1 ' and F2 or F2 ', with
And the condition of F3 or F3 ', if F4 is not in appropriate range, the fatigue strength of the steel after ageing treatment is not stable sometimes
Ground improves, and can not steadily inhibit the reduction of the toughness after ageing treatment.That is, having in the case where F4 is less than 0.012
When can not make sulfide-based field trash, oxide system field trash fine dispersion, the fatigue strength of the steel after ageing treatment does not have
It steadily improves, can not steadily inhibit the reduction of the toughness after ageing treatment.Therefore, F4 is set as 0.012 or more.In order to fill
Get field trash micronized effect, F4 is preferably 0.014 or more.In addition, F4 is more preferably 0.016 or more.
In addition, F4 more increases, field trash micronized effect more can be played, but if F4 is more than 0.08, then instead sometimes
The coarsening that will lead to oxide system field trash leads to the reduction of high-temperature ductility, therefore the upper limit of F4 is 0.08 or less.F4 is preferred
For 0.07 hereinafter, more preferably 0.06 or less.
< structure of steel (microscopic structure) >
In the following, the structure of steel (microscopic structure) to time hardening steel of the present embodiment is illustrated.
As described above, not preferably generating a large amount of just analysis ferrite before ageing treatment.Moreover, from the sight of machinability
Point sets out, and does not also preferably generate a large amount of martensite.Therefore, make the ageing treatment of time hardening steel of the present embodiment
Preceding main phase is that bainite is critically important.
That is, in the tissue before ageing treatment, needing to make the area of bainite to ensure sufficient machinability and being dissolved V
Rate is 70% or more.Furthermore the area ratio of bainite is preferably 80% or more, and most preferably bainite is single-phase, that is to say, that most
It is preferred that the area ratio of bainite is 100%.In the case where the area ratio of bainite is less than 100%, in addition to the shellfish as main phase
Other than family name's body is mutually ferritic phase, pearlitic structrure and martensitic structure etc., and the fewer these phases, tissue the better.
The age hardening capability of < steel and the relationship > of machinability and fatigue strength
It is the generally cylindrical shaped of 35mm that diameter, which is made, in steel, and the temperature of the steel is being maintained 120 minutes at 620 DEG C
In the case of the ascending amount of Vickers hardness of steel when being defined as age hardening capability (age-hardenability) of steel, this reality
The lower limit value of the age hardening capability for the steel that the mode of applying is related to is preferably 30Hv, more preferably 33Hv, 35Hv or 40Hv.Furthermore
It is that age-hardening processing is carried out to steel of the present embodiment to make by the processing of the temperature of steel holding 120 minutes at 620 DEG C
Make common Ageing conditions when mechanical part.In the case where age hardening capability is 30Hv or more, present embodiment
The steel being related to has good machinability before ageing treatment, has good fatigue strength after ageing treatment.
The manufacturing method of < time hardening steel and used time hardening steel (machinery) component manufacturing method >
The manufacturing method of the time hardening steel of present embodiment is not particularly limited, and using general method melting and is adjusted
Whole chemical composition.
Hereinafter, showing the time hardening steel of the present embodiment that will be manufactured as described above as material, to make
Make an example of the method for the mechanical part of automobile, industrial machine, building machinery etc..
Firstly, the steel that above-mentioned range is adjusted to by chemical composition be fabricated for shape components time hardening steel (with
It is known as " intermediate materials " down).
As above-mentioned intermediate materials, can be by steel billet obtained from ingot split rolling method, by continuous casting material split rolling method
Obtained from steel billet or by any material such as rod iron obtained from these hot rolling of steel billet or hot forging.But in intermediate materials
When production, in the case where the temperature region for being easy precipitation V carbide maintains certain time, it is possible to no longer effective hardening energy
Power.For example, the temperature of intermediate materials is tieed up in the range of 540~700 DEG C after split rolling method or after hot rolling or hot forging
In the case where having held 30 minutes or more, it is possible to no longer effective hardening capacity.But if according to general method, in cogging
After rolling or after hot rolling or hot forging, intermediate materials are placed under room temperature environment, then such situation will not occur.
Then, above-mentioned intermediate materials are hot-forged, and then carry out machining to be processed into defined component shape
Shape.
About above-mentioned hot forging, for example, by intermediate materials after 1200~1250 DEG C are heated 5~60 minutes, so that smart
The mode that surface temperature after forging is 1100 DEG C or more is forged, then, by the average cold of 800~400 DEG C of temperature region
But speed is set as 15~60 DEG C/min to be cooled to room temperature.Such average cooling rate can be placed by the steel after forging
Get off in room temperature environment and is readily derived.But in the case where cooling velocity is less than 15 DEG C/min, it is possible in cooling
V carbide is precipitated, so that age hardening capability becomes 30Hv or less.
In this way after cooling, and then machining is carried out, is processed into defined component shape.
Finally, implementing ageing treatment to the thick profile for being configured to defined component shape, obtain having desired characteristic
Automobile, industrial machine, building machinery etc. mechanical part.
Above-mentioned ageing treatment, for example, 540~700 DEG C temperature region, preferably 560~680 DEG C of humidity province
Domain, the temperature region further preferably at 580~660 DEG C carry out.The retention time of the ageing treatment, for example, 30~1000 points
Clock etc., according to the size (quality) of mechanical part come appropriate adjustment.
In the case where aging temperature is less than 540 DEG C, it can not be sufficiently formed V carbide or V carbonitride, obtained not
To desired age hardening capability 30Hv.On the other hand, in the case where aging temperature is more than 700 DEG C, it is formed by V
Carbide or V carbonitride coarsening, therefore be helpless to harden, it cannot get desired age hardening capability 30Hv.Similarly,
In the case where the retention time was less than 30 minutes, it can not be sufficiently formed V carbide or V carbonitride, therefore cannot get institute's phase
The age hardening capability 30Hv of prestige.On the other hand, in the case where the retention time being more than 1000 minutes, it is formed by V carbide
Or V carbonitride coarsening, therefore be helpless to harden, it cannot get desired age hardening capability 30Hv.
It carries out as described above, time hardening steel of the present embodiment can be produced and using it as material
Mechanical part.
Embodiment
Hereinafter, by embodiment 1,2, the present invention will be described in more detail.
Condition in embodiment described below 1,2, be for confirm exploitativeness and effect of the invention and use one
A condition example, the present invention are not limited by this condition example.In addition, without departing from the gist of the invention and this can be reached
The purpose of invention, the present invention can use various conditions.
(embodiment 1)
The steel 1~26 of chemical composition shown in table 1 has been refined using 50kg vacuum fusion furnace.
Steel 1~13 in table 1 is steel of the chemical composition in range given to this invention.On the other hand, the steel in table 1
14~26 be the steel that chemical composition is unsatisfactory for condition given to this invention.
Furthermore " < 0.001 " in the column Ti indicates the content of the Ti as impurity lower than the inspection as emission spectrographic analysis
Survey the 0.001% of lower limit value.
After the ingot of each steel heats at 1250 DEG C, it is hot-forged the bar steel at diameter 60mm.Each bar steel being hot-forged out temporarily exists
Natural cooling is cooled to room temperature in atmosphere.Then, and then using the bar steel for being cooled to room temperature it is heated to as intermediate materials
1250 DEG C, the bar steel that processing temperature is set as 950 DEG C or more to be hot-forged into diameter 35mm again.This 2nd time hot forging is for mould
It is quasi- to be forged into component shape and carry out.Bar steel natural cooling in an atmosphere after 2nd hot forging, is cooled to room temperature.2nd heat
Cooling velocity when forging is measured using radiation thermometer.The average cooling rate of 800~400 DEG C of temperature region after hot forging
(" cooling velocity " is denoted as in table 2) is all 50 DEG C/min.
For obtained steel 1~26, a part among the bar steel for the diameter 35mm being hot-forged out, in no implementation timeliness
Under the state (state of i.e. cooling state) of processing, after 100mm is respectively cut away in the both ends of bar steel, cut from remaining central portion
It materialses, the investigation of the area ratio of the bainite in Vickers hardness and tissue before having carried out ageing treatment.
On the other hand, the remainder of the bar steel for the diameter 35mm being hot-forged out is implemented and is kept for 120 minutes at 620 DEG C
Ageing treatment then after 100mm is respectively cut away in the both ends of bar steel, cut sample from remaining center portion, carry out
The investigation of Vickers hardness after ageing treatment.
In addition, sample is cut from the bar steel after ageing treatment, after having carried out ageing treatment for obtained steel 1~26
Charpy-type test in absorb can and low-cycle fatigue intensity and fatigue strength investigation.
Vickers hardness measurement is implemented as described below.
Firstly, will carry out it is crosscutting so that cut surface become detection faces bar steel filled with resin, will test face carry out mirror
It grinds to have prepared sample in face.Then, according to " Vickers hardness test-test method " in JIS Z 2244 (2009), for
Neighbouring 10 points in the portion R/2 (" R " indicate radius) of detection faces, are set as 9.8N for load to implement Determination of Hardness.To above-mentioned 10
The hardness measurements of a point carry out arithmetic average, the Vickers hardness by obtained value as the bar steel.Furthermore in ageing treatment
Preceding Vickers hardness is to be judged as substantially low, as target in 290Hv situation below.In addition, after ageing treatment
In the case that the difference (hereinafter referred to as hardening capacity Δ HV) of Vickers hardness before Vickers hardness and ageing treatment is 30Hv or more, judgement
It is sufficiently high for age hardening capability, as target.
The measurement of the area ratio of bainite in tissue is implemented as described below.
Firstly, the sample nital corruption for having carried out resin landfill and mirror ultrafinish that Determination of Hardness will be used for
Erosion.Tissue is had taken with 200 times of multiplying power using optical microscopy to the sample after corrosion.Image solution is passed through by the photo shot
It analyses to determine the area ratio of bainite.In the case where the area ratio of bainite is 70% or more, it is judged as tissue fully
Bainite, as target.
About toughness, the standard sample with the U-shaped notch that notch depth is 2mm and kerf bottom radius is 1mm is used
Implement.Absorbing at 20 DEG C after the ageing treatment evaluated in its Charpy-type test can be the situation of 50J or more
Under, it is judged as sufficiently high, as target.
About fatigue strength, produces and be uniaxially stretched the fatigue testing specimen of compression-type to be investigated.That is, from the R/2 of bar steel
The diameter of parallel portion shown in FIG. 1 is produced with forging direction parallel (length direction of bar steel) as 3.4mm, the length of parallel portion in portion
Degree is the smooth fatigue testing specimen of the shape of 12.7mm, in room temperature, atmosphere, the item that stress ratio 0.05, test speed are 10Hz
Fatigue test has been carried out under part.Under the conditions described above, number 10 will be applied in stress repetition7What is be not broken under secondary is maximum
Stress is as fatigue strength.In the case where fatigue strength is 425MPa or more, it is judged as that fatigue strength is sufficiently high, as
Target.
Low-cycle fatigue intensity is found out using the following method.
Firstly, in the way of producing position as the portion R/2 of bar steel, with forging direction parallel (length direction of bar steel) from
The length in length and breadth that bar steel produces the face transversal to length direction is respectively 13mm, the cuboid that length is 100mm.Then, into
And the position in the length direction center in a face of above-mentioned cuboid (that is, face with fatigue evaluation position) is provided with radius
The half-circular cutouts of 2mm, to obtain four-point bending sample.Low-cycle fatigue test carries out in room temperature, atmosphere, passes through following sides
Formula carries out: four-point bending fatigue test is carried out the stress ratio 0.1, fulcrum spacing 45mm, test frequency 5Hz under conditions of.?
Under conditions of above-mentioned, apply stress load repeatedly, by 5 × 103Strength definition under secondary is low-cycle fatigue intensity, carries out intensity
Evaluation is judged as that low-cycle fatigue intensity is sufficiently high in the case where low-cycle fatigue intensity is 520MPa or more, as
Target.
Table 2 shows above-mentioned each investigation result.It is 70% by the area ratio of bainite furthermore in " bainite " column
Above, the situation for having reached target is expressed as " GOOD ", and the situation that will be less than 70%, miss the mark is expressed as " BAD ".Separately
Outside, in table 2, " absorption can " in Charpy-type test be expressed as " Charpy impact absorb can ".
As shown in Table 2, " example of the present invention " of test number A1~A13 with chemical composition given to this invention, when
Vickers hardness hv before effect processing is 290 hereinafter, by ageing treatment, and Vickers hardness hardens 30Hv or more, Charpy impact examination
The absorption tested can also be 50J or more, also, fatigue strength is 425MPa or more, and low-cycle fatigue intensity is 520MPa or more,
Target is reached, the fatigue strength and toughness after ageing treatment can have both with the machinability before ageing treatment.
In contrast, it is unsatisfactory for " comparative example " of defined test number B1~B13 of the invention, does not all obtain target
At least a certain item performance in performance.
(embodiment 2)
It has been refined using 50kg vacuum fusion furnace and has changed Ca content, REM relative to the steel 1 of chemical composition shown in table 1
The steel 27~39 of at least one in content and F4 value.
Steel 1 and steel 27,30,33,36~39 in table 3, are steel of the chemical composition in range given to this invention.Separately
On the one hand, the steel 28,29,31,32,34,45 in table 3, is the steel that chemical composition is unsatisfactory for condition given to this invention.
Furthermore " < 0.001 " in the column Ti indicates the content of the Ti as impurity lower than the inspection as emission spectrographic analysis
Survey the 0.001% of lower limit value.
The ingot of each steel is hot-forged the bar steel at diameter 60mm after 1250 DEG C of heating.Each bar steel being hot-forged out, temporarily big
Natural cooling in gas, is cooled to room temperature.Then, and then using the bar steel for being cooled to room temperature 1250 are heated to as intermediate materials
DEG C, the bar steel that processing temperature is set as 950 DEG C or more to be hot-forged into diameter 35mm again.This 2nd time hot forging is to simulate forging
It causes component shape and carries out.Bar steel after 2nd hot forging, natural cooling, is cooled to room temperature in an atmosphere.2nd hot forging
When cooling velocity measured using radiation thermometer.Average cooling rate (the table 4 of 800~400 DEG C of temperature region after hot forging
In be expressed as " cooling velocity ") all for 50 DEG C/min.
For obtained steel 1 and steel 27~39, ageing treatment has been carried out similarly with the method implemented in embodiment 1
Preceding Vickers hardness, the area ratio of the bainite in tissue, the absorption energy in Charpy-type test, low-cycle fatigue intensity and tired
The investigation of labor intensity.Table 4 shows above-mentioned each investigation result.Furthermore each statement in table 4 is same as the statement in table 2.
As shown in Table 4, at least one of Ca content, REM content and F4 value are set as more more suitable than test number A1
Test number A27,30,33,36~39 of value, compared with testing number A1, fatigue strength is high.This is because with test number A1
It compares, sulfide-based field trash or oxide system field trash more imperceptibly dispersed reason.
In contrast, some in Ca content, REM content and F4 value is located at the test other than the range of the present application
" comparative example " of number B28, B29, B31, B32, B34, B35, compared with testing number A1, fatigue strength or toughness are low.This is
Since compared with testing number A1, sulfide-based field trash or oxide system field trash are coarseer, therefore lead to fatigue strength
The reduced reason of reduction or toughness.
Industrial availability
Time hardening steel according to the present invention, the hardness before ageing treatment are 290Hv hereinafter, can expect good cut
Cutting property.Moreover, if passing through the ageing treatment implemented after machining, dimension using time hardening steel of the invention
Family name's hardness hardens 30Hv or more, therefore can obtain the fatigue strength of 425MPa or more.Moreover, if using timeliness of the invention
Hardenability steel, then the absorption at 20 DEG C after ageing treatment can be 50J or more, and the toughness as caused by ageing treatment reduces to obtain
Abundant inhibition.Moreover, if low-cycle fatigue intensity can be made to reach 520MPa using time hardening steel of the invention
More than.Therefore, time hardening steel of the invention can be used as the machine of automobile, industrial machine, building machinery etc. with being well suited for
The material of tool component.
Claims (3)
1. a kind of time hardening steel, which is characterized in that chemical composition are as follows:
In terms of quality %, contain
C:0.05~0.20%,
Si:0.01~0.50%,
Mn:1.50~2.50%,
S:0.005~0.080%,
Cr:0.03~1.60%,
Al:0.005~0.050%,
V:0.25~0.50%,
Nb:0.010~0.100%,
Ca:0.0005~0.0050%,
REM:0.001~0.05%,
Also,
P be restricted to 0.030% hereinafter,
Ti is limited to less than 0.005%,
N is limited to less than 0.0080%,
Surplus includes Fe and impurity,
The area ratio of bainite structure is 70% or more,
Moreover, following F1 indicated by formula (1) are 0.68 or more, the F2 indicated by formula (2) is 0.85 hereinafter, by formula (3) table
The F3 shown is 0.00 or more, also, is 0.012~0.08 by the F4 that formula (4) indicate,
F1=C+0.3 × Mn+0.25 × Cr (1)
F2=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V (2)
F3=-4.5 × C+Mn+Cr-3.5 × V (3)
F4=10 × Ca+REM (4)
The symbol of element in formula (1)~(4) means the content in terms of quality % of the element.
2. a kind of time hardening steel, which is characterized in that chemical composition are as follows:
In terms of quality %, contain
C:0.05~0.20%,
Si:0.01~0.50%,
Mn:1.50~2.50%,
S:0.005~0.080%,
Cr:0.03~1.60%,
Al:0.005~0.050%,
V:0.25~0.50%,
Nb:0.010~0.100%,
Ca:0.0005~0.0050%,
REM:0.001~0.05%,
Moreover, meet any of composition condition shown in following < a >~< c > or more,
< a > Mo:0.01~1.0%,
A side or two sides in < b > Cu:0.01~0.30% and Ni:0.01%~0.30%,
< c > Bi:0.01~0.400%,
Also,
P be restricted to 0.030% hereinafter,
Ti is limited to less than 0.005%,
N is limited to less than 0.0080%,
Surplus includes Fe and impurity,
The area ratio of bainite structure is 70% or more,
Moreover, following F1 ' indicated by formula (1 ') are 0.68 or more, the F2 ' indicated by formula (2 ') is 0.85 hereinafter, by formula
(3 ') F3 ' indicated is 0.00 or more, also, is 0.012~0.08 by the F4 that formula (4) indicate,
F1 '=C+0.3 × Mn+0.25 × Cr+0.6 × Mo ... (1 ')
F2 '=C+0.1 × Si+0.2 × Mn+0.15 × Cr+0.35 × V+0.2 × Mo ... (2 ')
F3 '=- 4.5 × C+Mn+Cr-3.5 × V-0.8 × Mo ... (3 ')
F4=10 × Ca+REM ... (4)
The symbol of element in formula (1 ')~(3 ') and (4) means the content in terms of quality % of the element.
3. a kind of manufacturing method for the component for having used time hardening steel, which is characterized in that including following process:
Forging process: time hardening steel of any of claims 1 or 2 is heated 5~60 minutes at 1200~1250 DEG C, so
It is forged in the way of making 1100 DEG C of the surface temperature after finish forge or more afterwards, then, by 800~400 DEG C of temperature region
Average cooling rate be set as 15~60 DEG C/min to be cooled to room temperature；
Machining process: machining is carried out to the steel after forging；With
Ageing treatment process: the temperature region by the steel after machining at 540~700 DEG C is kept for 30~1000 minutes.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
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| JP2015-070839 | 2015-03-31 | ||
| JP2015070839 | 2015-03-31 | ||
| PCT/JP2016/058585 WO2016158470A1 (en) | 2015-03-31 | 2016-03-17 | Age-hardening steel and method of manufacturing parts using age-hardening steel |
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| Publication Number | Publication Date |
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| CN107250410A CN107250410A (en) | 2017-10-13 |
| CN107250410B true CN107250410B (en) | 2018-12-21 |
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| CN201680010678.5A Expired - Fee Related CN107250410B (en) | 2015-03-31 | 2016-03-17 | Time hardening steel and used time hardening steel component manufacturing method |
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| Country | Link |
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| US (1) | US20180044757A1 (en) |
| EP (1) | EP3279356A4 (en) |
| JP (1) | JP6536673B2 (en) |
| KR (1) | KR101918432B1 (en) |
| CN (1) | CN107250410B (en) |
| WO (1) | WO2016158470A1 (en) |
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| US11814709B2 (en) | 2018-10-31 | 2023-11-14 | Jfe Steel Corporation | Steel for nitrocarburizing and nitrocarburized component, and methods of producing same |
| CN110257713A (en) * | 2019-07-16 | 2019-09-20 | 内蒙古科技大学 | A kind of low-carbon aged steel and preparation method thereof |
| BR112023024874A2 (en) | 2021-06-16 | 2024-02-15 | Arcelormittal | METHOD FOR PRODUCING A STEEL PART AND STEEL PART |
| CN116024495B (en) * | 2022-12-21 | 2024-06-14 | 中国兵器科学研究院宁波分院 | Martensitic precipitation hardening steel and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS5257460Y2 (en) * | 1972-06-30 | 1977-12-27 | ||
| JPS62263922A (en) * | 1986-05-09 | 1987-11-16 | Japan Casting & Forging Corp | Production of forged steel |
| JP3900690B2 (en) * | 1998-06-26 | 2007-04-04 | 愛知製鋼株式会社 | Age-hardening high-strength bainitic steel and method for producing the same |
| JP3440894B2 (en) * | 1998-08-05 | 2003-08-25 | Ｊｆｅスチール株式会社 | High strength hot rolled steel sheet excellent in stretch flangeability and method for producing the same |
| JP4435953B2 (en) * | 1999-12-24 | 2010-03-24 | 新日本製鐵株式会社 | Bar wire for cold forging and its manufacturing method |
| JP4415219B2 (en) * | 2004-07-28 | 2010-02-17 | 大同特殊鋼株式会社 | Age hardened steel |
| JP5123335B2 (en) * | 2010-01-28 | 2013-01-23 | 本田技研工業株式会社 | Crankshaft and manufacturing method thereof |
| JP5343923B2 (en) | 2010-05-18 | 2013-11-13 | 新日鐵住金株式会社 | Method of manufacturing age-hardening steel and machine parts |
| WO2012067181A1 (en) * | 2010-11-17 | 2012-05-24 | 新日本製鐵株式会社 | Steel for nitriding purposes, and nitrided member |
| JP5620336B2 (en) * | 2011-05-26 | 2014-11-05 | 新日鐵住金株式会社 | Steel parts for high fatigue strength and high toughness machine structure and manufacturing method thereof |
| JP5974623B2 (en) * | 2012-05-07 | 2016-08-23 | 大同特殊鋼株式会社 | Age-hardening bainite non-tempered steel |
| JP5825199B2 (en) * | 2012-05-24 | 2015-12-02 | 新日鐵住金株式会社 | Method of manufacturing age-hardening steel and machine parts |
| JP5567747B2 (en) * | 2012-07-26 | 2014-08-06 | Ｊｆｅスチール株式会社 | Soft nitriding steel, soft nitriding component and manufacturing method thereof |
| KR101750643B1 (en) * | 2013-10-02 | 2017-06-23 | 신닛테츠스미킨 카부시키카이샤 | Age hardening steel |
-
2016
- 2016-03-17 EP EP16772353.5A patent/EP3279356A4/en not_active Withdrawn
- 2016-03-17 KR KR1020177020209A patent/KR101918432B1/en active IP Right Grant
- 2016-03-17 CN CN201680010678.5A patent/CN107250410B/en not_active Expired - Fee Related
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| JP6536673B2 (en) | 2019-07-03 |
| EP3279356A4 (en) | 2018-10-03 |
| CN107250410A (en) | 2017-10-13 |
| KR20170097743A (en) | 2017-08-28 |
| WO2016158470A1 (en) | 2016-10-06 |
| EP3279356A1 (en) | 2018-02-07 |
| US20180044757A1 (en) | 2018-02-15 |
| KR101918432B1 (en) | 2018-11-13 |
| JPWO2016158470A1 (en) | 2017-12-21 |
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