CN109790602A - Steel - Google Patents
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- CN109790602A CN109790602A CN201680089493.8A CN201680089493A CN109790602A CN 109790602 A CN109790602 A CN 109790602A CN 201680089493 A CN201680089493 A CN 201680089493A CN 109790602 A CN109790602 A CN 109790602A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
Abstract
The steel that a technical solution of the invention is related to, chemical component contains C:0.15~0.40%, Mn:0.10~1.50%, S:0.002~0.020%, Ti:0.005~0.050%, B:0.0005~0.0050%, Bi:0.0010~0.0100%, P:0.020% or less, N:0.0100% or less, Si:0% more than and less than 0.30%, Cr:0~1.50%, Al:0~0.050%, Mo:0~0.20%, Cu:0~0.20%, Ni:0~0.20% and Nb:0~0.030% as unit of quality %, and surplus includes Fe and impurity.
Description
Technical field
The present invention relates to steel.
Background technique
Cold forging (including rolling forming) can make epidermis and dimensional accuracy of product etc. good, in turn compared with hot forging
Yield rate is also good, therefore the manufacturing method as the more small-sized mechanical part of bolt etc that is widely used.Passing through
Cold forging in the case where manufacturing mechanical part, uses such as JIS G 4051, JIS G 4052, JIS G 4104, JIS G
4105, the mechanical structure carbon steel of the middle carbon of the defineds such as JIS G 4106, steel alloy are as raw material, by for example such as wire rod heat
Rolling-annealing (or spheroidizing)-wire drawing-cold forging-quenching and such manufacturing process is tempered final product is made
The case where it is more.The characteristics of above-mentioned common manufacturing process is the process that attached annealing or spheroidizing before cold forging.
Additional anneal or the reason of spheroidizing are because there is a problem of in manufacture below before cold forging: the carbon steel of middle carbon and
Steel alloy is under rolled the case where (that is, air-cooled without heat treatment after hot rolling), and the hardness of rolling stock is high, cold forging
When mold loss it is significant, therefore manufacturing cost is high；Under rolled, the ductility of raw material is insufficient, is easy to produce in cold forging
Raw crackle, therefore yield rate reduces；Etc..
But since annealing spends great cost, in order to reduce the manufacturing cost of component, needing to develop can be saved
The slightly steel of annealing operation.According to such requirement, the so-called bolt in steel added with micro B was once developed
Boron steel (such as patent document 1 and patent document 3).The characteristics of boron steel, is: being closed by carbon content and Cr, Mo etc. for reducing steel
The additive amount of gold element improves ductility while reducing the hardness of wire rod of rolled, thus without annealing, and benefit
The addition by alloying element is compensated with the effect that the micro B addition bring hardenability by not increasing rolling stock hardness improves
The reduction of hardenability caused by the reduction of amount.
In order to embody the effect improved by micro B addition bring hardenability, need B in austenite in solid solution shape
State.On the other hand, the amount of B (being solid-solution in the B in steel) is dissolved there are BN in the case where the nitrogen of solid solution condition, can be generated in steel
It reduces, the effect for the raising hardenability that thus B has is lost.Therefore, following work are generally carried out: in boron steel, passing through addition
With N there is the Ti of strong affinity in advance to fix the N in steel as TiN, inhibits the generation of BN.For example, in patent document 4
In describe by make Ti/N (quality % ratio) be 4 or more the precipitation to inhibit BN.In principle, if make Ti/N 3.42 with
On, then it is able to suppress the precipitation of BN.
But common boron steel as described above, compared with previous steel, in Quench heating, a part of austenite grain holds
It is also easy to produce abnormal grain length coarsening greatly, that is, be easy to produce so-called coarse grain.The component of coarse grain is produced, can be produced
It is raw by quenching when the heat treatment that generates become larger caused by dimensional accuracy deterioration and impact value, fatigue strength and prolong
The reduction of the characteristics of components such as slow fracture characteristics.Therefore, in the high-strength bolt that especially tensile strength is 800MPa or more, prevent
Only coarse grain generation is big project in practical use.In order to inhibit the generation of such big caused coarse grain of abnormal grain length,
In order to by the Grain boundary pinning of austenite grain, make quantity in tissue more disperse pinning particle (precipitate etc.), that is, make fine
Particle disperse to be effective in large quantities.
The reason of coarse grain is easy to produce in boron steel mainly following two points.
(1) using boron steel as in the case where component materials, since the annealing operation after the cold forging of boron steel is omitted,
Boron steel will directly be heated to austenite region from cold working tissue.In this case, due to the influence because of cold working it is generated due to
The excessive miniaturization and crystal particle diameter of austenite grain it is partial uneven, therefore become a part of crystal grain and be easy to produce
The big state of raw exception grain length.
(2) in above-mentioned boron steel, by the addition of Ti, the N in steel is fixed as TiN, thus without generate with
Toward carbon steel and steel alloy in the AlN that is effectively acted on as pinning particle, also, TiN is coarseer compared with AlN, therefore
Can not imperceptibly it disperse, it is difficult to ensure be the quantity for preventing pinning particle required for coarse grain.
Since annealing operation is omitted, the principal element of above-mentioned (1) is inevitable, therefore, in order to improve the main of (2)
How, factor ensures that the quantity of pinning particle becomes the main points for preventing coarse grain from generating in boron steel.
From such situation, it is proposed that for preventing boron steel from generating the technology of coarse grain.For example, in patent text
It offers and describes in 5 and patent document 6 instead of AlN, TiN and using the precipitate TiC finer than TiN and Ti (CN) as pinning
Particle.In these techniques, in order to ensure for prevent pinning particle required for coarse grain quantity, it is specified that: make to quench
Dispersion total number is 20/100 μm in steel before heating and after hot rolling2Above diameter is 0.2 μm of TiC and Ti below
(CN).By dispersing such nano-precipitation in large quantities, these precipitates in Quench heating
It plays a role as the pinning particle for carrying out pinning to austenite grain boundary.It, can be stable against in boron steel according to the technology
Coarse grain is generated, the steel for applying the technology is widely used as now as that can omit the cheap bolt steel of annealing operation
Material.
But there are disadvantages for above-mentioned technology.That is, being largely dispersed with fine TiC, Ti (CN) in tissue after hot rolling
In the case where, there are following side effects, that is, due to the precipitation strength by fine precipitate particle generation, causes ferritic
Hardness increases, therefore has the problem of softening effect reduction by boron steel bring hot-finished material.That is, make fine TiC,
In the case that the amount of Ti (CN) increases, though can inhibit the generation of coarse grain, the hardness of rolling stock is due to precipitation strength
Increase, thus the service life reduction of mould for cold forging.On the contrary, if inhibiting the amount of fine TiC, Ti (CN), though it can inhibit to roll
The hardness of prepared material, but generate coarse grain.That is, inhibiting coarse grain using fine TiC, Ti (CN)
It generates and the hardness of the rolling stock before cold forging is inhibited to there is the relationship runed counter to.Therefore, difficult only with above-mentioned technology
To fully achieve rolling stock softening and steadily both inhibition coarse grains.
Also describe in patent document 7 prevents from boron steel from generating the same technology of the technology of coarse grain thinking with above-mentioned
Think.That is, being through the relationship that makes the content of Ti, Nb, Al, N within the scope of some, to make the carbonitride of these elements in steel
Dispersion, prevents the technology of coarse grains.It also describes and is cut by the Bi of 0.01% or more addition to improve in patent document 7
The effect of cutting property.But in patent document 7, as the effect of Bi, the effect for improving machinability is only disclosed.About Bi with
The relationship of the coarsening characteristic of crystal grain is absolutely not recorded.Due to adding Bi for the purpose of machinability improvement effect,
The case where Bi of addition more amount is only had studied in patent document 7.In this case, as documented by patent document 7, load
The reduction of hot-workability caused by the heart is added by Bi.
Patent Document 8 discloses a kind of hardened case processing steel, which, which is handled, uses steel, with
Previous example is compared, though in the case where having carried out carburizing at high temperature, excellent resistance to coarse grains characteristic is also played, also,
Even if also showing excellent cold-workability without soft annealing.But patent document 8 also only proposes: as ensuring resistance to crystalline substance
The means of grain coarsening characteristic, utilize fine Ti carbide and double carbide containing Ti etc..In patent document 8, in order to
Ensure cold-workability and keep hot-rolled temperature extremely low, therefore, compromises the productivity of hardened case processing steel.
Citation
Patent document
Patent document 1: the flat 5-339676 bulletin of Japanese Laid-Open
Patent document 2: Japan's fairness 5-63524 bulletin
Patent document 3: the clear 61-253347 bulletin of Japanese Laid-Open
Patent document 4: the flat 3-47918 bulletin of Japanese Laid-Open
Patent document 5: No. 3443285 bulletin of Japan's patent
Patent document 6: No. 3490293 bulletin of Japan's patent
Patent document 7: Japanese Laid-Open 2000-328189 bulletin
Patent document 8: Japanese Laid-Open 2006-265704 bulletin
Summary of the invention
The project of Cold Forging Steel first is that: in order to improve the forging of steel and the productivity of steel, not after hot rolling and
It is annealed and and is remained steel soft without using the manufacturing condition of damage productivity before cold forging.Cold Forging Steel it is another
Project is: it is high-intensitive in order to be assigned to mechanical part, high hardenability is played after cold forging.Moreover, Cold Forging Steel is another
Project is: the deterioration such as the dimensional accuracy, impact value of mechanical part, fatigue strength and delayed fracture characteristic in order to prevent will press down
Refrigeration forging after quenching when coarse grain generate.As described above, the prior art can not solve all these projects simultaneously.
As the means for inhibiting coarse grain to generate, the scheme using TiC and Ti (CN) proposed in the prior art, due to because being precipitated
Strengthen and make the steel hardening after hot rolling and before cold forging, therefore damages the forging and productivity of steel.
The present invention is completed in view of above-mentioned project.That is, project of the invention is to provide without using TiC and Ti
(CN) etc. thus the generation of coarse grain when Ti carbide and Ti carbonitride but inhibit quenching manufacturing, forging and is quenched
The excellent steel of mechanical property after fire.
The gist of the invention is as follows.
(1) steel that a technical solution of the invention is related to, chemical component as unit of quality % containing C:0.15~
0.40%, Mn:0.10~1.50%, S:0.002~0.020%, Ti:0.005~0.050%, B:0.0005~0.0050%,
Bi:0.0010~0.0100%, P:0.020% or less, N:0.0100% or less, Si:0% are more than and less than 0.30%, Cr:0
~1.50%, Al:0~0.050%, Mo:0~0.20%, Cu:0~0.20%, Ni:0~0.20% and Nb:0~
0.030%, surplus includes Fe and impurity.
(2) steel according to above-mentioned (1), above-mentioned chemical component can be containing selected from Si as unit of quality %:
0.01% more than and less than a kind or two kinds among 0.30%, Cr:0.01~1.50% and Al:0.001~0.050% with
On.
(3) steel according to above-mentioned (1) or (2), above-mentioned chemical component can be containing selected from Mo as unit of quality %:
0.02~0.20%, a kind or two among Cu:0.02~0.20%, Ni:0.02~0.20% and Nb:0.002~0.030%
Kind or more.
(4) according to described in any item steel of above-mentioned (1)~(3), the N fixation index I defined using formula 1 belowFNIt can
Think 0 or more.
IFN=[Ti] -3.5 × [N] ... (formula 1)
Wherein, [Ti] is the Ti content as unit of quality %, and [N] is the N content as unit of quality %.
(5) according to described in any item steel of above-mentioned (1)~(4), the Ti-Nb system precipitate defined using formula 2 below
Generate index IPIt can be 0.0100 or less.
IP=0.3 × [Ti]+0.15 × [Nb]-[N] ... (formula 2)
Wherein, [Ti] is the Ti content as unit of quality %, and [Nb] is the Nb content as unit of quality %, and [N] is
N content as unit of quality %.
In accordance with the invention it is possible to which coarse grain when quenching after providing the softening before being able to achieve cold forging and inhibition cold forging produces
Raw steel.Moreover, it relates to steel, will not be cracked in casting and when rolling etc., and can be not to system
Manufacturing apparatus increase burden in the range of under conditions of manufacture, therefore manufacturing is excellent.By the way that steel of the present invention is applied to
Steel wire, the loss of mold when being able to suppress cold forging, improves the service life of mold.In addition, by by steel of the present invention
Applied to steel wire, the die cost of high price can reduce, therefore can aid in especially tensile strength is 800MPa
The reduction of the manufacturing cost of above high-strength bolt.Moreover, the machinability of steel of the present invention is also excellent.Therefore, this hair
Bright contribution industrially is very big.
Specific embodiment
The steel that one embodiment of the present invention is related to is illustrated.Steel of the present embodiment has spy below
Sign.
(a) steel of the present embodiment, chemical component contain C:0.15~0.40%, Mn as unit of quality %:
0.10~1.50%, S:0.002~0.020%, Ti:0.005~0.050%, B:0.0005~0.0050%, Bi:0.0010
~0.0100%, P:0.020% or less, N:0.0100% or less, Si:0% more than and less than 0.30%, Cr:0~1.50%,
Al:0~0.050%, Mo:0~0.20%, Cu:0~0.20%, Ni:0~0.20% and Nb:0~0.030%, surplus include
Fe and impurity.
(b) steel according to above-mentioned (a), above-mentioned chemical component can be containing selected from Si as unit of quality %:
0.01% more than and less than a kind or two kinds among 0.30%, Cr:0.01~1.50% and Al:0.001~0.050% with
On.
(c) according to above-mentioned (a) or (b) described in steel, above-mentioned chemical component as unit of quality % can containing be selected from Mo:
0.02~0.20%, a kind or two among Cu:0.02~0.20%, Ni:0.02~0.20% and Nb:0.002~0.030%
Kind or more.
(d) according to described in any item steel of above-mentioned (a)~(c), the N fixation index I defined using formula 1 belowFNIt can
Think 0 or more.
IFN=[Ti] -3.5 × [N] ... (formula 1)
Wherein, [Ti] is the Ti content as unit of quality %, and [N] is the N content as unit of quality %.
(e) according to described in any item steel of above-mentioned (a)~(d), the Ti-Nb system precipitate defined using formula 2 below
Generate index IPIt can be 0.0100 or less.
IP=0.3 × [Ti]+0.15 × [Nb]-[N] ... (formula 2)
Wherein, [Ti] is the Ti content as unit of quality %, and [Nb] is the Nb content as unit of quality %, and [N] is
N content as unit of quality %.
In addition, by carrying out bolt processing, quenching, tempering, energy using well known method to steel of the present embodiment
Enough bolts for not generated coarse grain with excellent productivity.
The present inventor about unlike the prior art, inhibit coarse grain generate technology studied, it is described existing
Technology is the increase made as causing to generate significant ferrite hardness due to precipitation strength, to generate the increasing of steel hardness
Add, damages the technology of the fine dispersions such as the particle of the cold-workability of steel, TiC and Ti (CN).It is above-mentioned to be characterized in based on this hair
Bright people for obtained from inhibiting the big technology of abnormal grain length of austenite grain when steel Quench heating to carry out a intensive study with
Lower opinion.
(1) inhibit the exception of austenite grain when Quench heating using the Bi of 0.0100% or less such denier
Grain length is big, can obtain the excellent cold working component such as dimensional accuracy and mechanical property.
(2) by the effect of above-mentioned Bi, can independent of utilized in the past as pinning particle precipitate (TiC,
Ti (CN), NbC) (that is, the cold-workability for not damaging steel) and inhibit the abnormal grain length of austenite grain big.Thereby, it is possible to inhibit
The hardness of rolling stock after hot rolling improves the cold-workability of steel.
(3) on the other hand, understand fully: when Bi content is more than 0.0100%, the high-temperature ductility of steel is reduced, thus in steel
Crackle, flaw are easy to produce in manufacturing process's (casting, rolling process etc.), the yield rate of steel reduces.But also understand fully: working as Bi
When content is more than 0.0100%, embrittlement of grain boundaries is generated in steel after quenching, damages the mechanical property of steel.Therefore it also understands fully:
In steel of the present embodiment, although must contain Bi, its content needs to be suppressed in extremely low level.
Hereinafter, steel of the present embodiment is described in detail.
Firstly, being illustrated to the chemical component of steel of the invention.Hereinafter, the unit " % " about chemical component indicates
" quality % ".
[C:0.15~0.40%]
C is to improve the intensity of the steel with tempered martensite and the element that needs.In order to make quenched tension
Intensity is 800MPa or more, needs C content being set as 0.15% or more.The lower limit of preferred C content is 0.17%, 0.19%,
Or 0.23%.
On the other hand, if C content is more than 0.40%, the excessive high hardness of the rolling stock after hot rolling, mould for cold forging
Service life significantly reduces.Therefore, the upper limit of C content is set as 0.40%.The upper limit of preferred C content is 0.35%, 0.34%,
0.33% or 0.30%.
[Mn:0.10~1.50%]
Mn is to the effective element of hardenability for improving steel.In order to ensure for by quench obtain that martensite needs can
Quenching property needs Mn content being set as 0.10% or more.The lower limit of preferred Mn content is 0.20%, 0.35% or 0.40%.
On the other hand, if Mn content is more than 1.50%, the excessive high hardness of the rolling stock after hot rolling and before cold forging, therefore
The service life of the mold of cold forging reduces significantly.Therefore, the upper limit of Mn content is set as 1.50%.The upper limit of preferred Mn content
It is 1.30%, 1.00% or 0.80%.
[S:0.002~0.020%]
S has following effects: as MnS, TiS and Ti2C2S exists in steel, in Quench heating as pinning grain
Son plays a role, and thus inhibits the abnormal grain length of austenite grain big.Therefore, it is necessary to S content is set as 0.002% or more.It is excellent
The lower limit of the S content of choosing is 0.003%.
But in steel of the present embodiment, inhibit abnormal grain length big due to using Bi, even if S content
It is fewer than the prior art also enough.Moreover, S makes the original austenite crystal boundary of quenched steel when S content is more than 0.020%
Embrittlement reduces delayed fracture resistance characteristics (hydrogen embrittlement resistance).Moreover, because above-mentioned Ti2C2S is the machinability for damaging steel
Particle, therefore when S content is more than 0.020%, it is possible to produce the deterioration of the machinability of steel.Therefore, it is necessary to limit S content
It is 0.020% or less.It is preferred that the upper limit value of S content is 0.015%, 0.010% or 0.005%.[Ti:0.005~
0.050%]
Ti has following effects: compound is formed with C, N, S in steel, as TiN, Ti (CN), TiC, TiS, Ti2C2S etc.
Ti system field trash exists in steel, plays a role in Quench heating as pinning particle, thus inhibits the different of austenite grain
Normal grain length is big.In addition, Ti due to the solid solution N in steel have strong affinity, be in advance using the solid solution N in steel as
TiN is fixed, to the extremely effective element of generation for inhibiting BN.In boron steel, in order to ensure the raising to hardenability is effectively solid
The content of molten B needs to inhibit the generation of BN.Therefore, it is necessary to Ti content is set as 0.005% or more.Under preferred Ti content
It is limited to 0.010%, 0.015% or 0.020%.
But in steel of the present embodiment, due to inhibiting abnormal grain length big using Bi, even if Ti content
It is fewer than the prior art also enough.Moreover, Ti system inclusion particle generates precipitation strength, heat when Ti content is more than 0.050%
The excessive high hardness of rolling stock after rolling, therefore the service life of the mold of cold forging reduces significantly.In order to improve Ti system field trash
The content of particle and the hardness for inhibiting the rolling stock after hot rolling need to keep hot-rolled temperature low, but this is from productivity, Yi Jishe
It is undesirable from the point of view of standby service life etc..Moreover, can largely generate the cutting of damage steel in the case where improving Ti content
The particle Ti of property2C2S generates the deterioration of machinability, therefore becomes difficult to steel application machining of the present embodiment.
Therefore, the upper limit of Ti content is set as 0.050%.Preferred Ti content is 0.040% or less, 0.030% or less, be less than
0.030% or 0.025% or less.[B:0.0005~0.0050%]
B is the element for facilitating the hardenability of steel in the case where containing microly and improving, and can not be made after hot rolling and cold
The hardness of rolling stock before forging, which increases, obtains the effect of hardenability raising, and cold forging and quenched hardness can be made to increase
Greatly.B is especially bolt boron steel necessary element.In addition, B has by strengthening original in original austenite cyrystal boundary segregation
Beginning austenite grain boundary, to inhibit the effect of intercrystalline failure.In the case where to obtain above-mentioned effect, need to set B content
It is 0.0005% or more.It is preferred that the lower limit value of B content is 0.0010%, 0.0012% or 0.0015%.
On the other hand, when B content is more than 0.0050%, effect saturation.Therefore, by B content be set as 0.0050% with
Under.It is preferred that the upper limit value of B content is 0.0030%, 0.0025%, 0.0020% or 0.0018%.
[Bi:0.0010~0.0100%]
Micro Bi about about 0.0010~0.0100% degree when steel is quenched to the influence given of tissue, so far for
The example that only do not studied in detail excessively still.Present inventor have discovered that austenite grain when micro Bi inhibits Quench heating
Abnormal grain length it is big, thus have the effect of preventing coarse grain from generating.In addition, the present inventors have additionally discovered that, due to for inhibit it is different
The Bi content that normal grain length is big and needs is micro, therefore the hardness of the rolling stock after hot rolling can not be made to increase and be inhibited and quench
The effect of the above-mentioned Bi of the generation of coarse grain when fire heating.In the case where to obtain above-mentioned effect, need Bi
Content is set as 0.0010% or more.The lower limit value of Bi content is preferably 0.0020%, 0.0025% or 0.0030%.
On the other hand, when Bi content is more than 0.0100%, not only its effect is saturated, but also the high-temperature ductility of steel reduces,
Therefore crackle, flaw are easy to produce in manufacturing process's (casting, rolling process etc.) of steel, yield rate reduces.Moreover, when Bi contains
When amount is more than 0.0100%, embrittlement of grain boundaries is generated in steel after quenching, damages the mechanical property of steel.Therefore, Bi content is set
It is 0.0100% or less.Bi content is preferably less than 0.0100%, 0.0080% or less or 0.0060% or less.
[P:0.020% or less]
P is impurity, is the member for making original γ embrittlement of grain boundaries, reducing the delayed fracture resistance characteristics (hydrogen embrittlement resistance) of steel
Element.Therefore, it is necessary to P content is limited to 0.020% or less.It is preferred that the upper limit value of P content be 0.015%, 0.013% or
0.010%.
It is not required for the project for solution steel of the present embodiment as P, the lower limit value of P content is
0%.But in order to inhibit the cost of the refining procedure for reducing P content, the lower limit value of P content can also be set as
0.001%.
[N:0.0100% or less]
N is forming compound with B, as BN present in the steel, makes to be dissolved B amount and reduce, damage is by B bring
Improve the effect of hardenability.N is harmful in steel of the present embodiment, therefore the lower limit value of N content is 0%.But in order to
The cost for inhibiting the refining procedure for reducing N content, the lower limit value of N content can also be set as to 0.0001%, 0.0005%,
Or 0.0010%.
In the case where more than the N content, increase for Ti content required for being fixed using the N in steel as TiN, therefore, it is desirable to
N content is reduced as far as possible.Therefore, it is necessary to N content is limited to 0.0100% or less.It is preferred that the upper limit value of N content is
0.0070%, 0.0050% or 0.0040%.
In the spring steel that present embodiment is related to, it also can according to need also to contain with aftermentioned range and be selected from
1 kind or two or more among Si, Cr and Al.But since Si, Cr and Al are not required, Si, Cr and Al are respectively
Content lower limit be 0%.
[Si:0% is more than and less than 0.30%]
As described above, in steel of the present embodiment, the lower limit value of Si content is 0%.But Si is to raising
The hardenability of steel, the effective element of temper softening drag for improving martensite.In the case where to obtain above-mentioned effect, preferably
Si content is set as to be greater than 0% or 0.01% or more.The lower limit value of Si content can also be set as 0.05% or 0.15%.
But when Si content becomes 0.30% or more, the hardness of the steel (rolling stock) after hot rolling and before cold forging it is upper
Rising amount becomes larger, therefore the service life reduction of the mold of cold forging.Therefore, Si content is set as less than 0.30%.Preferred Si content
The upper limit be 0.27%, 0.25% or 0.20%.
[Cr:0~1.50%]
As described above, in steel of the present embodiment, the lower limit value of Cr content is 0%.But Cr is to raising
The hardenability of steel, the effective element of temper softening resistance for improving martensite.In the case where to obtain above-mentioned effect, preferably
Cr content is set as to be greater than 0% or 0.01% or more.The lower limit value of Cr content can also be set as 0.10%, 0.20% or
0.30%.
On the other hand, when Cr content is more than 1.50%, the excessive high hardness of the rolling stock after hot rolling and before cold forging, therefore
The service life of the mold of cold forging reduces significantly.Therefore, the upper limit of Cr content is set as 1.50%.The upper limit of preferred Cr content
It is 1.20%, 1.00% or 0.80%.
[Al:0~0.050%]
Al is the effective element of deoxidation to steel, but in the case where carrying out deoxidation using other elements (Si, Ti etc.),
Can also not necessarily it contain.Therefore, the lower limit value of Al content is 0%.But it is excellent in order to obtain by Al bring deoxidation effect
Choosing contains 0.001% or more, 0.005% or more or 0.010% or more.
On the other hand, when Al content is more than 0.050%, coarse field trash can be generated, toughness reduction of steel etc. is asked
Topic becomes significant.Therefore, even if the upper limit of Al content is also set as 0.050% in the case where containing Al.The upper limit of Al content
Preferably 0.040%, 0.030% or 0.025%.
In the spring steel that present embodiment is related to, it also can according to need also to contain with aftermentioned range and be selected from
1 kind or two or more among Mo, Cu, Ni and Nb.But since Mo, Cu, Ni and Nb are not required, Mo,
The lower limit of the respective content of Cu, Ni and Nb is 0%.
[Mo:0~0.20%]
As described above, in steel of the present embodiment, the lower limit value of Mo content is 0%.But Mo is even if it
Content is the element for also contributing to the hardenability of steel on a small quantity and improving.In the case where to obtain above-mentioned effect, preferably Mo is contained
Amount is set as 0.02% or more.The lower limit value of further preferred Mo content is 0.03%, 0.04% or 0.05%.
On the other hand, due to the alloying element that Mo is high price, when Mo content is more than 0.20%, in manufacturing cost
It is upper unfavorable.Therefore, even if Mo content is also set as 0.20% or less in the case where containing Mo.It is preferred that the upper limit value of Mo content
It is 0.16%, 0.13% or 0.10%.
[Cu:0~0.20%]
As described above, in steel of the present embodiment, the lower limit value of Cu content is 0%.But Cu makes steel
The element that corrosion resistance improves.In the case where to obtain above-mentioned effect, Cu content is preferably set as 0.02% or more.Further
It is preferred that the lower limit value of Cu content is 0.05%.
On the other hand, when Cu content is more than 0.20%, the high-temperature ductility of steel is reduced, manufacturing when damaging continuous casting etc.
Problem becomes significant.Therefore, even if Cu content is also set as 0.20% or less in the case where containing Cu.It is preferred that Cu content
Upper limit value is 0.15%, 0.10% or 0.08%.
[Ni:0~0.20%]
As described above, in steel of the present embodiment, the lower limit value of Ni content is 0%.But Ni makes steel
The element that corrosion resistance improves, in addition, being the also effective element of the raising to the toughness of steel.The case where to obtain above-mentioned effect
Under, Ni content is preferably set as 0.02% or more.The lower limit value of further preferred Ni content be 0.03%, 0.04% or
0.05%.
On the other hand, due to the alloying element that Ni is high price, when Ni content is more than 0.20%, in manufacturing cost
It is upper unfavorable.Therefore, even if Ni content is also set as 0.20% or less in the case where containing Ni.It is preferred that the upper limit value of Ni content
It is 0.15%, 0.12%, 0.10% or 0.08%.
[Nb:0~0.030%]
As described above, in steel of the present embodiment, the lower limit value of Nb content is 0%.But Nb is with following
Effect: compound is formed with the C in steel, is existed in steel as the Nb system such as NbC or TiNb (CN) field trash, in Quench heating
Inhibit the abnormal grain length of austenite grain big as pinning particle.In the case where to obtain above-mentioned effect, preferably Nb is contained
Amount is set as 0.002% or more.The lower limit value of further preferred Nb content is 0.003%, 0.005% or 0.006%.
On the other hand, when Nb content is more than 0.030%, not only its effect is saturated, but also Nb system field trash generates precipitation
Strengthen, therefore manufacturing when damage continuous casting.Alternatively, in this case, since Nb system field trash generates precipitation strength, heat
The excessive high hardness of rolling stock after rolling.Therefore, when Nb content is more than 0.030%, the reduction of manufacturing and cold forging
The problems such as significant reduction in the service life of mold, becomes significant.Therefore, even if being also set as Nb content in the case where containing Nb
0.030% or less.It is preferred that the upper limit value of Nb content is 0.015%, 0.013% or 0.010%.
Steel of the present embodiment, containing above-mentioned alloying component, the surplus (rest part) of chemical component includes
Fe and impurity.In the present embodiment, so-called impurity refers to mixed by raw materials such as ore, waste materials when industrialness manufactures steel
Enter and the mixed ingredient due to other factors, is the level for not damaging the function and effect of steel of the present embodiment
Amount ingredient.
[N fixation index IFN: preferably 0 or more]
Brought effect is contained by above-mentioned B in order to obtain, is needed by reducing the N being dissolved in steel (solid solution
N) inhibit the generation of BN.Therefore, it is intended that while reducing the content of the N in steel, and making in steel containing Ti by N with
The form stable of TiN it is fixed, as a result, reduce solid solution N amount.In order to, to obtain above-mentioned effect, preferably will using the fixed N of Ti
The N fixation index I defined using following formula 1FNIt is set as 0 or more.It can also be by N fixation index IFNLower limit value be set as 0.0005,
0.0010,0.0014 or 0.0050.But even if it is not particularly limited N fixation index IFNAs long as Ti content and N content are controlled
In above-mentioned range, then the steel of the present embodiment also softening before cold forging, and it is able to suppress coarse crystalline substance when quenching
The generation of grain.
IFN=[Ti] -3.5 × [N] ... (formula 1)
Furthermore [Ti] and [N] in above-mentioned formula 1 indicates that Ti content and N in the steel as unit of quality % contain
Amount, these elements are denoted as 0% when not containing.
[Ti-Nb system precipitate generates index IP: preferably 0.0100 or less]
As described above, preferably: using Ti to fix N as TiN, reduced to make to be dissolved N amount.But it does not preferably comprise
Content is more than the Ti for being the amount fixing TiN and needing.As described above, Ti also with C and S etc. in conjunction with and form nano-precipitation,
These nano-precipitations are possible to cause adverse effect to the characteristic of steel of the present embodiment.In addition, the inventors discovered that
Also have and Ti similarly effect for Nb.
Specifically, as fine TiC, Ti (CN) of the precipitate present in steel, NbC, TiNb (CN) and
Ti2C2The Ti-Nb such as S system precipitate, with following effects: inhibiting the different of austenite grain as pinning particle in Quench heating
Normal grain length is big, thus inhibits the generation of coarse grain.But precipitate particle is scattered in hot rolling in large quantities in these Ti-Nb systems
In the case where in tissue afterwards, there are following side effects: due to the precipitation strength by fine precipitate particle generation, leading to iron
The hardness of ferritic increases.Therefore, in the case where exceedingly largely dispersion in steel in these Ti-Nb system precipitate particles, hot rolling
The excessive high hardness of rolling stock afterwards, therefore the problems such as service life significant decrease of the mold of cold forging, becomes significant.Moreover, as above
It states like that, Ti2C2S will lead to the generation of machinability deterioration.Therefore, in steel of the present embodiment, these are preferably limited
The amount of Ti-Nb system precipitate particle.
In order to inhibit the hardness after the rolling after hot rolling, it is desirable to which the Ti-Nb system precipitate calculated by following formula 2 is raw
Exponentially IPIt is set as 0.0100 or less.Ti-Nb system precipitate can also be generated into index IPIt is set as 0.0075 or less, is less than
0.0050,0.0045 or less, 0.0040 or less or 0.0035 or less.But it is raw even if being not particularly limited Ti-Nb system precipitate
Exponentially IPAs long as Ti content, Nb content and N content are controlled in above-mentioned range, steel of the present embodiment
The softening before cold forging, and it is able to suppress the generation of coarse grain when quenching.
IP=0.3 × [Ti]+0.15 × [Nb]-[N] ... (formula 2)
Furthermore in above-mentioned formula 2 [Ti], [N] and [Nb], indicate that the Ti content in the steel as unit of quality %, N contain
Amount and Nb content, these elements are denoted as 0% when not containing.
Then, the suitable manufacturing method of the steel of present embodiment is illustrated.
In order to manufacture the steel of present embodiment, the steel of the above-mentioned chemical component of melting in converter, as needed through two
Slab is made by continuous casting in secondary refining procedure.By reheating the slab, and split rolling method is carried out, is made for section
Such as the raw material (steel billet) of the wire rod rolling of 162mm square (long 162mm × wide 162mm).Then, by steel billet 1000~1280
It is heated at a temperature of DEG C degree, then, by carrying out wire rod rolling, is formed as the wire shape of 6~20mm of diameter.Thereafter, exist
Under hot, after coiling into roll-shape using devices for taking-up, it is cooled to room temperature.Thus obtain the steel of present embodiment.
Furthermore in steel of the present embodiment, it is suppressed due to generating the amount of Ti system precipitation particles of precipitation strength,
Therefore in the manufacturing method of steel of the present embodiment, do not need in order to inhibit the hardness of steel and reduce hot-rolled temperature to
It increases burden to equipment of hot rolling, in addition, being difficult to generate the defects of rising caused crackle and flaw by hardness in steel.And
And steel of the present embodiment, it does not anneal after hot rolling, is able to suppress its hardness.Therefore, present embodiment is related to
Steel be also excellent on this point productivity is high.
Steel according to the present embodiment, the production of coarse grain when softening and inhibition before can be realized cold forging quench
It is raw.In addition, the steel of present embodiment, will not crack, manufacturing is excellent in casting, when rolling.
The hardness of steel of the present embodiment is not made special due to can suitably adjust depending on the application
It limits.But in the case where being necessary to ensure that forging, the hardness of steel of the present embodiment, which is set as Hv180 or less, to be advisable,
It is preferably to be set as Hv170 or less or Hv160 or less.The lower limit value of the hardness of steel of the present embodiment, does not limit particularly
It is fixed, but can consider according to its chemical component is essentially about Hv130 or about Hv140.Steel of the present embodiment, even if
Without annealing after hot rolling, also it can make its hardness in above-mentioned optimum range.In addition, steel of the present embodiment is cut
Cutting property is also excellent.
In addition, being kept for 30 points in the temperature for being heated to such as 840 DEG C~1100 DEG C for steel of the present embodiment
It is quenched, and then protected in 150 DEG C~450 DEG C of temperature range heating under conditions of clock, thereafter water cooling or oil are cold
In the case where the tempering held, its tensile strength can be made to reach 800MPa or more.Therefore, steel of the present embodiment,
It is suitable as requiring the material of high-intensitive component.But steel of the present embodiment used as quenching with steel
In the case of, heat treatment condition is not particularly limited, and can be suitable for depending on the application selection.
The purposes of steel of the present embodiment is not particularly limited, but is preferably applied to through cold forging and quenching system
The high strength machine parts, particularly high-strength bolt made.Using the high steel of the present embodiment of forging as high-strength
In the case where the materials'use for spending mechanical part, the loss of mold when being able to suppress cold forging improves the service life of mold.In addition,
Due to can reduce the cost of the mold of high price, can aid in especially tensile strength is the high-strength of 800MPa or more
Spend the reduction of the manufacturing cost of bolt.
Embodiment
Then, the present invention is illustrated using embodiment, but the present invention is not limited by example below.
Firstly, having the steel of chemical component shown in table 1-1 and table 1-2 using converter melting, and then pass through continuous casting
Slab is made.Furthermore in table 1-1 and table 1-2, about content in impurity level element below, content is with sky
White expression is calculating N fixation index IFNAnd Ti-Nb system precipitate generates index IPWhen, it is considered as " 0 mass % ".In addition,
In table 1-1 and table 1-2, the value other than prescribed limit of the invention has been attached to underscore.Thus obtained slab is confirmed
Whether slab surface crack is produced.When confirming slab surface crack, by notch inspection (check scarf), removing
Casting billet surface is observed after the oxide skin of casting billet surface, investigates crack depth.In the crackle of the surface of slab detection depth 1mm or more
When, it is determined as slab surface crack when " having " continuous casting, and " unqualified " is determined as manufacturing.By manufacturing evaluation result
It is shown in table 2-1 and table 2-2.
Equal heat diffusion treatment, split rolling method are carried out as needed to the slab, obtaining section is 162mm square (long 162mm
× wide 162mm) wire rod rolling raw material (steel billet).Then, by steel billet 1000~1280 DEG C of degree at a temperature of heat,
Then, wire rod rolling is carried out, the wire rod (spring steel) of diameter 10mm is thus made.
The sample of Vickers hardness measurement is cut from the wire rod after rolling.Specifically, parallel relative to rolling direction
Direction cut with the central axis comprising wire rod section sample.After being ground to the section cut, determine from line
Start the Vickers hardness at the 1/4 depth position (1/4) of gauge or diameter of wire in the surface of material.Test load is set as 10kgf, will be to 4
Point is measured obtained average value as " hardness after rolling " and is recorded in table 2-1 and table 2-2, as prediction cold forging
The index in the service life of mold.Hardness for rolling stock is more than the sample of HV180, due to not obtaining mould for cold forging
Service life sufficient improvement, therefore forging is determined as " unqualified ".By forging evaluation result is shown in table 2-1
With table 2-2.
In addition, the influence of wire drawing, cold forging (cold working) when wire rod to be processed into bolt shape in order to simulate, to wire rod into
It after the cold drawing processing that the row contraction percentage of area is 70%, is heated 30 minutes in 840 DEG C~1100 DEG C of temperature, carries out water cooling and quench
Fire, to freeze austenite structure as the original austenite crystal boundary of martensitic structure.Then, the examination for being quenched
Sample is tempered in A1 point temperature region below as needed, is cut in the direction parallel with drawing direction relative to rolling
The sample in the section with the center comprising drawable material.After being ground to the section of the sample cut, shown by corroding
Reveal original austenite crystal boundary, by using optical microphotograph sem observation, to determine the original austenite after quenching and tempering
Grain size.The measurement of original austenite grains degree is carried out according to JIS G0551 standard.About measurement visual field, in multiplying power 400
10 visual fields or more are set as under times, even if original austenite grains degree is No. 5 big crystal grains below there are 1 sample, are also sentenced
Be set to is to produce the sample of coarse grain.It will be by carrying out original austenite grains degree to the sample for being heated to various temperature
Observation and measurement are so that critical (minimum) heating temperature made clear, generation coarse grain is defined as the crystal grain of the sample
Coarsening temperature, and the index as resistance to coarse grains characteristic.Coarse grains temperature is 900 DEG C of samples below, resistance to crystalline substance
Grain coarsening characteristic is poor, therefore, it is determined that being " unqualified ".Coarse grains temperature measuring result is shown in table 2-1 and table 2-2.
It is clear that from table 2-1 and table 2-2, as A1~A32 of example of the present invention, the hardness of the wire rod after rolling is low,
It can expect to make the service life of mould for cold forging to improve, therefore forging is excellent, when Quench heating after cold working, even if heating
Coarse grain is not also generated more than 900 DEG C, moreover, also not generating the face crack of slab in continuous casting, therefore the fragmentation of slab
Rate is low, and therefore, manufacturing is excellent.Furthermore it is above-mentioned for measure original austenite grains degree be heat-treated after this hair
Bright example A1~A32, all tensile strength with 800MPa or more.
In contrast, in the case where comparative example, above-mentioned forging, coarse grain prevent characteristic, some in manufacturing
Item is poor.That is, B1~B4, since Bi additive amount is excessive, high-temperature ductility reduces, manufacturing is poor.B5~B7 is not due to adding
Bi or additive amount are very few, therefore coarse grain prevents characteristic poor.B8, B9 since the additive amount of Ti is excessive, alternatively, relative to
Ti additive amount, N content are a small amount of, Ti-Nb system precipitate generation index IPExcess, therefore the hardness of the wire rod after rolling is high,
Forging is poor.
Table 2-1
Table 2-2
Industrial availability
In accordance with the invention it is possible to coarse crystalline substance when providing softening when being able to achieve cold forging and inhibiting the quenching after cold forging
The steel of the generation of grain.Moreover, it relates to steel, will not be cracked in casting, when rolling, and can be not to system
Manufacturing apparatus increase burden in the range of under conditions of manufacture, therefore manufacturing is excellent.By the way that steel of the present invention is applied to
Steel wire, the loss of mold when being able to suppress cold forging, improves the service life of mold.In addition, by by steel of the present invention
Applied to steel wire, the die cost of high price can reduce, therefore can aid in especially tensile strength is 800MPa
The reduction of the manufacturing cost of above high-strength bolt.Moreover, the machinability of steel of the present invention is also excellent.Therefore, this hair
Bright contribution industrially is very big.
Claims (5)
1. a kind of steel, which is characterized in that chemical component is contained as unit of quality %
C:0.15~0.40%,
Mn:0.10~1.50%,
S:0.002~0.020%,
Ti:0.005~0.050%,
B:0.0005~0.0050%,
Bi:0.0010~0.0100%,
P:0.020% or less,
N:0.0100% or less,
Si:0% more than and less than 0.30%,
Cr:0~1.50%,
Al:0~0.050%,
Mo:0~0.20%,
Cu:0~0.20%,
The and of Ni:0~0.20%
Nb:0~0.030%,
Surplus includes Fe and impurity.
2. steel according to claim 1, which is characterized in that the chemical component is contained as unit of quality % to be selected from
Si:0.01% more than and less than 0.30%,
The and of Cr:0.01~1.50%
Al:0.001~0.050%
Among a kind or two or more.
3. steel according to claim 1 or 2, which is characterized in that the chemical component is contained as unit of quality % to be selected from
Mo:0.02~0.20%,
Cu:0.02~0.20%,
The and of Ni:0.02~0.20%
Nb:0.002~0.030%
Among a kind or two or more.
4. described in any item steel according to claim 1~3, which is characterized in that referred to using the N fixation of formula 1 below definition
Number IFNIt is 0 or more,
IFN=[Ti] -3.5 × [N] ... formula 1
Wherein, [Ti] is the Ti content as unit of quality %, and [N] is the N content as unit of quality %.
5. steel according to any one of claims 1 to 4, which is characterized in that using the Ti-Nb system of formula 2 below definition
Precipitate generates index IPFor 0.0100 hereinafter,
IP=0.3 × [Ti]+0.15 × [Nb]-[N] ... formula 2
Wherein, [Ti] is the Ti content as unit of quality %, and [Nb] is the Nb content as unit of quality %, and [N] is with matter
Measure the N content that % is unit.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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| PCT/JP2016/078558 WO2018061101A1 (en) | 2016-09-28 | 2016-09-28 | Steel |
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| US (1) | US20190256957A1 (en) |
| EP (1) | EP3521469A4 (en) |
| JP (1) | JP6798557B2 (en) |
| KR (1) | KR20190041502A (en) |
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| CN113667906A (en) * | 2021-07-22 | 2021-11-19 | 河钢股份有限公司 | Fine steel for straight weather-resistant high-strength bolt and production method thereof |
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| JP7155644B2 (en) * | 2018-06-18 | 2022-10-19 | 日本製鉄株式会社 | bolt |
| CN111100976A (en) * | 2019-09-20 | 2020-05-05 | 河南中原特钢装备制造有限公司 | Heat treatment process for preventing cracking of steel for glass mold after forging |
| CN114855093B (en) * | 2022-03-28 | 2023-10-03 | 本钢板材股份有限公司 | High-cold-heading formability low-carbon low-silicon aluminum-containing cold-heading steel hot-rolled wire rod and preparation method thereof |
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| JPH05339676A (en) | 1992-06-11 | 1993-12-21 | Nippon Steel Corp | Steel for machine structure excellent in cold workability and its manufacture |
| JP3443285B2 (en) | 1997-07-23 | 2003-09-02 | 新日本製鐵株式会社 | Hot rolled steel for cold forging with excellent crystal grain coarsening prevention properties and cold forgeability, and method for producing the same |
| JP2000328189A (en) | 1999-05-11 | 2000-11-28 | Sumitomo Metal Ind Ltd | Steel for cold forging |
| JP4448047B2 (en) | 2005-03-25 | 2010-04-07 | 株式会社神戸製鋼所 | A steel for skin hardening that has excellent grain coarsening resistance and cold workability, and can omit softening annealing. |
| JP2007239028A (en) * | 2006-03-08 | 2007-09-20 | Honda Motor Co Ltd | Heat treatment method for steel material |
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| JP5821794B2 (en) * | 2012-07-18 | 2015-11-24 | 新日鐵住金株式会社 | Hardened steel, its manufacturing method, and hardened steel |
-
2016
- 2016-09-28 US US16/329,463 patent/US20190256957A1/en not_active Abandoned
- 2016-09-28 JP JP2018541768A patent/JP6798557B2/en active Active
- 2016-09-28 WO PCT/JP2016/078558 patent/WO2018061101A1/en unknown
- 2016-09-28 CN CN201680089493.8A patent/CN109790602B/en not_active Expired - Fee Related
- 2016-09-28 KR KR1020197007851A patent/KR20190041502A/en not_active Application Discontinuation
- 2016-09-28 EP EP16917654.2A patent/EP3521469A4/en not_active Withdrawn
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63216952A (en) * | 1987-03-04 | 1988-09-09 | Daido Steel Co Ltd | Cold forging steel |
| JPH0797656A (en) * | 1993-09-30 | 1995-04-11 | Kobe Steel Ltd | Cold forging steel |
| CN104308089A (en) * | 2012-10-22 | 2015-01-28 | 宁波吉威熔模铸造有限公司 | Method for manufacturing automobile engine support |
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| CN113667906A (en) * | 2021-07-22 | 2021-11-19 | 河钢股份有限公司 | Fine steel for straight weather-resistant high-strength bolt and production method thereof |
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| EP3521469A4 (en) | 2020-03-11 |
| KR20190041502A (en) | 2019-04-22 |
| EP3521469A1 (en) | 2019-08-07 |
| JP6798557B2 (en) | 2020-12-09 |
| WO2018061101A1 (en) | 2018-04-05 |
| US20190256957A1 (en) | 2019-08-22 |
| CN109790602B (en) | 2021-03-02 |
| JPWO2018061101A1 (en) | 2019-07-04 |
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