CN100469934C - High-strength steel product excelling in fatigue strength and process for producing the same - Google Patents
High-strength steel product excelling in fatigue strength and process for producing the same Download PDFInfo
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- CN100469934C CN100469934C CNB2004800010493A CN200480001049A CN100469934C CN 100469934 C CN100469934 C CN 100469934C CN B2004800010493 A CNB2004800010493 A CN B2004800010493A CN 200480001049 A CN200480001049 A CN 200480001049A CN 100469934 C CN100469934 C CN 100469934C
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Abstract
A high-strength and high-fatigue-strength steel having a base metal strength of 1000 MPa or more and a rotating bending fatigue strength of 550 MPa or more is provided. The steel contains 0.3-0.8 percent by mass of C, 0.01-0.9 percent by mass of Si, 0.01-2.0 percent by mass of Mn, and Fe and unavoidable impurities as the remainder. The steel has a ferrite-cementite structure having a grain size of 7 mum or less or a ferrite-cementite-pearlite structure having a grain size of 7 mum or less. A surface metal of the steel after high-frequency induction quenching has a martensite structure having a prior austenite grain size of 12 mum or less. Alternatively, a surface metal of the steel after nitriding has a fine structure having a ferrite grain size of 10 mum or less.
Description
Technical field
The present invention relates to a kind of trolley part that uses bar steel, for example High Strength Steel and manufacture method thereof of the excellent in fatigue strength of constant velocity cardan joint, transmission rod, crank axle, connecting rod and wheel shaft etc. of being applicable to.
Background technology
Goods such as connecting rod and wheel shaft carry out high temperature forging or rolling forming, carry out machining thereafter and make.Goods such as constant velocity cardan joint, transmission rod, crank axle and wheel shaft, after being used to improve the annealing or Spheroidizing Annealing of machinability, carry out high temperature forging or rolling forming, carry out high-frequency quenching to a part or whole part thereafter, perhaps carry out nitriding treatment and make.For the car body lightweight, to the goods requirement high strength and the high fatigue lifeization of this purposes.
In the past, known in order to improve fatigue strength, it was the most effective reducing the maximum diameter of inclusion and the quantity of minimizing inclusion.
For example in patent documentation 1, proposed a kind ofly by suitably adjusting each composition such as Al, N, Ti, Zr and S, and the maximum diameter that makes sulfide makes purity more than 0.05% below 10 μ m, improves the method for fatigue strength.Yet, in high-strength material, be easy to generate intercrystalline failure if existence is subjected to repeated stress, and can not get the problem of target fatigue strength especially.
In addition, for example in patent documentation 2, proposed a kind of in wire or bar-shaped rolling stock, by will with axis parallel and apart from the axle center unit surface 100mm of the position of 1/4 diameter
2Middle oxide compound and the sulfide that exists is controlled at below 20, improves the method for fatigue characteristic and rolling contact fatigue characteristic.Yet in this method, the maximum value of fatigue strength only about 770MPa, can not satisfy recent requirement to bending fatigue strength.
Patent documentation 1: the spy opens flat 11-302778 communique
Patent documentation 2: the spy opens flat 11-1749 communique
Summary of the invention
The present invention develops in view of above-mentioned present situation, its purpose is, tissue is carried out suitable control when carrying out the composition adjustment, a kind of High Strength Steel and favourable manufacture method thereof are proposed, wherein, High Strength Steel intensity has following good intensity and fatigue strength simultaneously: intensity is more than 1000MPa, and rotoflector fatigue strength is more than 550MPa.
In addition, the object of the invention is, by suitably controlling mother metal tissue and skin section tissue, a kind of High Strength Steel and favourable manufacture method thereof are proposed, wherein, High Strength Steel has following good intensity and fatigue strength simultaneously: strength of parent is more than 1000MPa, and the rotoflector fatigue strength behind the high-frequency quenching or after the nitrogenize is more than 800MPa.
Inventors repeatedly attentively study for reaching above-mentioned purpose, and its result obtains following opinion.
(1),, only makes the crystallization particle diameter become fine and can not obtain target fatigue strength of the present invention though can improve intensity and fatigue strength simultaneously if make the crystallization particle diameter of steel become fine.
(2) if carry out the composition adjustment, make structure of steel not only generate fine ferrite, also generate fine cementite, can improve fatigue strength effectively.In addition, because this fine dispersion cementite has the effect that increases uniform elongation, thereby can improve the processibility of material.
(3) in order structure of steel to be become have the tissue of fine ferrite and fine cementite, outside the composition of steel was adjusted, the processing of implementing to be deformed into more than 1.0 550～700 ℃ temperature provinces was effective.
(4),,,, thereby can not get target fatigue strength of the present invention because high-frequency quenching thereafter makes coarsening if only make the crystallization particle diameter become fine though can improve intensity and fatigue strength simultaneously if make the crystallization particle diameter of steel become fine.
(5) if carry out the composition adjustment, make structure of steel not only generate fine ferrite, also generate fine cementite, this fine dispersion cementite and mother metal ferrite crystal boundary, when ratio-frequency heating as the nucleus of austenitizing and act on, owing to produce austenitizing, thereby the also miniaturization of martensitic original austenite particle diameter that finally obtains from a lot of nucleus.Its result also can improve intensity and fatigue strength greatly after high frequency quenches.
(6) when high-frequency quenching, the lower temperature tool effect that has greatly improved.
(7) if make the crystallization particle diameter of steel become fine, though can improve intensity and fatigue strength simultaneously, but thereafter when skin section is implemented nitriding treatment, if only make the crystallization particle diameter become fine, because nitriding treatment thereafter makes coarsening, thereby can not get target fatigue strength of the present invention.
(8) if carry out the composition adjustment, make structure of steel not only generate fine ferrite, also generate fine cementite, this fine dispersion cementite plays the effect of obstruction (pinning) when nitrogenize, suppress ferritic grain growing, therefore, the ferrite particle diameter of the skin section that finally obtains also becomes fine.Its result also can improve intensity and fatigue strength greatly behind nitriding treatment.
Embodiment
That is, main composition of the present invention is as follows.
1. the High Strength Steel of an excellent in fatigue strength, it is characterized in that, contain C:0.3～0.8 quality %, Si:0.01～0.9 quality % and Mn:0.01～2.0 quality %, surplus is the composition of Fe and unavoidable impurities, be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, perhaps ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m.
2. as the High Strength Steel of 1 described excellent in fatigue strength, it is characterized in that, for also containing the composition of Mo:0.05～0.6 quality %.
3. as the High Strength Steel of 2 described excellent in fatigue strength, it is characterized in that, be selected from Al:0.015～0.06 quality %, Ti:0.005～0.030 quality % for also containing, below the Ni:1.0 quality %, below the Cr:1.0 quality %, below the V:0.1 quality %, below the Cu:1.0 quality %, below the Nb:0.05 quality %, below the Ca:0.008 quality % and the composition more than a kind or 2 kinds in below the B:0.004 quality %.
4. as the High Strength Steel of 1,2 or 3 described excellent in fatigue strength, it is characterized in that the per-cent of organizing of cementite is more than the 4 volume %.
5. as the High Strength Steel of 2 described excellent in fatigue strength, it is characterized in that the skin section behind the high-frequency quenching becomes the martensitic stucture of original austenite particle diameter below 12 μ m.
6. as the High Strength Steel of 5 described excellent in fatigue strength, it is characterized in that, be selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
7. as the High Strength Steel of 2 described excellent in fatigue strength, it is characterized in that the ferrite particle diameter of the skin section behind the nitriding treatment is below the 10 μ m, and have the hardened layer that forms by nitriding treatment in the skin section of the steel of this excellent in fatigue strength.
8. as the High Strength Steel of 7 described excellent in fatigue strength, it is characterized in that, be selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
9. as the High Strength Steel of 7 or 8 described excellent in fatigue strength, it is characterized in that the per-cent of organizing of the cementite in the mother metal tissue is more than the 4 volume %.
10. the manufacture method of the High Strength Steel of an excellent in fatigue strength, it is characterized in that, to containing C:0.3～0.8 quality %, Si:0.01～0.9 quality % and Mn:0.01～2.0 quality %, surplus is the former material of steel of the composition of Fe and unavoidable impurities, implements to be deformed into processing more than 1.0 550～700 ℃ of temperature provinces.
11. as the manufacture method of the High Strength Steel of 10 described excellent in fatigue strength, it is characterized in that the former material of steel also contains Mo:0.05～0.6 quality %.
12. as the manufacture method of the High Strength Steel of 11 described excellent in fatigue strength, it is characterized in that the former material of steel is selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % is following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
13. as the manufacture method of the High Strength Steel of 11 described excellent in fatigue strength, it is characterized in that, 550～700 ℃ of temperature provinces the former material of steel is implemented to be deformed into processing more than 1.0, implement high-frequency quenching afterwards.
14. as the manufacture method of the High Strength Steel of 13 described excellent in fatigue strength, it is characterized in that the former material of steel is selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % is following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
15. as the manufacture method of the High Strength Steel of 11 described excellent in fatigue strength, it is characterized in that, 550～700 ℃ of temperature provinces the former material of steel is implemented to be deformed into processing 1.0 or more, afterwards to skin section enforcement nitriding treatment.
16. as the manufacture method of the High Strength Steel of 15 described excellent in fatigue strength, it is characterized in that the former material of steel is selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % is following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
Below, the present invention is specifically described.At first in the present invention, the one-tenth of steel is grouped into the reason that is defined in above-mentioned scope describes.
C:0.3～0.8 quality %
C is the necessary element of cementite that improves the intensity of mother metal and guarantee requirement.At this, if C contains quantity not sufficient 0.3 quality %, then can not get above-mentioned effect, on the other hand,, then can cause machinability, fatigue strength, forging reduction, thereby the C amount is defined in the scope of 0.3～0.8 quality % if surpass 0.8 quality %.
Si:0.01～0.9 quality %
Si not only acts on as reductor, and help to improve intensity, if but contain quantity not sufficient 0.01 quality %, this additive effect deficiency then, on the other hand, if surpass 0.9 quality % then can cause machinability and the reduction of forging property, thereby the Si amount is defined in the scope of 0.01～0.9 quality %.
Mn:0.01～2.0 quality %
Mn not only can improve intensity, and help to improve fatigue strength, if but contain quantity not sufficient 0.01 quality %, this additive effect deficiency then, on the other hand, if surpass 2.0 quality %, then can cause machinability and forging property variation, thereby the Mn amount is defined in the scope of 0.01～2.0 quality %.
More than basal component is illustrated, in the present invention, in addition can also suitably contain the element of the following stated.
Mo:0.05～0.6 quality %
Mo is the useful element of growth to the inhibition ferrite crystal grain, therefore need contain 0.05 quality % at least, if but add above 0.6 quality %, then can cause the machinability variation, thereby the Mo amount is defined in the scope of 0.05～0.6 quality %.
Al:0.015～0.06 quality %
Al is as the reductor of steel and act on.If yet containing quantity not sufficient 0.015 quality %, its additive effect deficiency on the other hand, if surpass 0.06 quality %, then can cause machinability and fatigue strength to reduce, thereby the Al amount is defined in the scope of 0.015～0.06 quality %.
Ti:0.005～0.030 quality %
Ti is because obstruction (pinning) effect of TiN, be to making the useful element of crystal grain miniaturization, in order to obtain this effect, at least to add 0.005 quality %, if but surpass that 0.030 quality % adds then the reduction that can cause fatigue strength, thereby the Ti amount is defined in the scope of 0.005～0.030 quality %.
Below the Ni:1.0 quality %
Ni to improve intensity and crackle when preventing to add Cu effective, if but surpass 1.0 quality % and add, then be easy to generate and hardening crack, thereby be defined in below the 1.0 quality %.
Below the Cr:1.0 quality %
Cr is effective to improving intensity, if but add above 1.0 quality %, then make the carbide stabilization, promote the generation of remaining carbide, grain-boundary strength is reduced, but also cause fatigue strength to reduce, thereby be limited to below the 1.0 quality %.
Below the V:0.1 quality %
V separates out owing to becoming carbide, thereby is the be used for element of organizing micronized effect of performance based on obstruction (pinning), even but add above 0.1 quality %, effect is also saturated, thereby is defined in below the 0.1 quality %.
Below the Cu:1.0 quality %
Cu is the useful element that intensity is improved by solution strengthening and precipitation strength, and helps to improve hardenability, if but content surpasses 1.0 quality %, then when high temperature process, be easy to generate crackle, and make the difficulty that becomes, thereby be defined in below the 1.0 quality %.
Below the Nb:0.05 quality %
Nb has by separating out the effect of obstruction (pinning) ferrite crystal grain, even but surpass 0.05 quality % and add, its effect is also saturated, thereby is defined in below the 0.05 quality %.
Below the Ca:0.008 quality %
Ca makes inclusion balling, improves the useful element of fatigue characteristic, if but add above 0.008 quality %, then have thickization of inclusion, make the tendency of fatigue characteristic variation on the contrary.Thereby be limited to below the 0.008 quality %.
Below the B:0.004 quality %
B not only improves fatigue characteristic by grain-boundary strengthening, still improves the useful element of intensity, even but add above 0.004 quality %, its effect is also saturated, thereby is limited to below the 0.004 quality %.
More than, be illustrated being fit to composition, but in the present invention, it is not enough only one-tenth being grouped into and being defined in above-mentioned scope, as described below, also very important to the adjustment of structure of steel.
Being organized as particle diameter is following ferrite and cementite tissues of 7 μ m, and perhaps particle diameter is following ferrite, cementite and pearlitic structures of 7 μ m
##
Tissue is if not ferrite below the 7 μ m and cementite tissue, and perhaps particle diameter is following ferrite, cementite and pearlitic structures of 7 μ m, then can not obtain target strength 〉=1000MPa in the present invention.Therefore, the ferrite particle diameter is limited to below the 7 μ m.More preferably below 5 μ m.
The mother metal tissue, be the tissue (be equivalent to the skin section quenching structure behind the high-frequency quenching beyond part) before the high-frequency quenching, if not particle diameter is ferrite and cementite tissue below the 7 μ m, perhaps particle diameter is following ferrite, cementite and pearlitic structures of 7 μ m, then can not obtain as the strength of parent more than the 1000MPa of target in the present invention.In addition, if the ferrite particle diameter not below 7 μ m, when then being suitable for high-frequency quenching thereafter, the original austenite particle diameter that high-frequency quenching is suitable for portion can not change to below the 12 μ m, can not improve fatigue strength.Therefore, the ferrite particle diameter with mother metal is limited to below the 7 μ m.More preferably below 5 μ m.
Mother metal tissue, the tissue before the nitriding treatment (be equivalent to the skin section nitride layer behind the nitriding treatment beyond part) just, if not particle diameter is ferrite and cementite tissue below the 7 μ m, perhaps particle diameter is following ferrite, cementite and pearlitic structures of 7 μ m, then can not obtain as the strength of parent more than the 1000MPa of target in the present invention.In addition, if the ferrite particle diameter not below 7 μ m, when then implementing nitriding treatment thereafter, the ferrite particle diameter of nitride layer can not become below the 10 μ m.Therefore, the ferrite particle diameter with mother metal is limited to below the 7 μ m.More preferably below 5 μ m.
If the ferrite particle diameter becomes below the 2 μ m, also may pearlitic structure disappear, become ferrite-cementite tissue, but this does not hinder to the present invention.
The amount of the cementite of separating out in addition, (tissue per-cent) in volume percent (volume %) preferably more than 4%.Cementite helps to improve fatigue strength, and because a large amount of fine separating out has the increase uniform elongation, improves the effect of the processibility of material.The size of the cementite of here, preferably separating out is greatly below about 1 μ m.More preferably below 0.5 μ m.And the either pearlite occurred of preferably separating out is greatly below 20 volume %.This perlite as mentioned above, also it doesn't matter even all do not separate out.Surplus beyond cementite, the perlite is organized as ferrite.This ferrite content from guaranteeing the viewpoint of processibility, is preferably more than the 40 volume %.In the manufacturing process of steel, in the warm forging operation,, can suitably obtain above-mentioned ferrite and cementite tissue, perhaps ferrite, cementite and pearlitic structure by being out of shape in the processing more than 1.0 550～700 ℃ temperature province.
If the skin section behind the high-frequency quenching be the original austenite particle diameter at the martensitic stucture original austenite particle diameter below the 12 μ m not below 12 μ m, then can not get in the present invention as the high bending fatigue strength more than the 800MPa of target.Therefore, the original austenite particle diameter in the tissue behind the high-frequency quenching is limited to below the 12 μ m.Preferably below 5 μ m.
By making mother metal be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, perhaps be ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m, and carry out high-frequency quenching under the following conditions, can obtain the tissue behind the above-mentioned high-frequency quenching.
The ferrite particle diameter of the skin section behind the nitriding treatment is below 10 μ m
If the skin section behind the nitriding treatment, just the ferrite particle diameter of nitride layer then can not get in the present invention as the high bending fatigue strength more than the 800MPa of target not below 10 μ m.Therefore, the ferrite particle diameter in the skin section tissue behind the nitriding treatment is limited to below the 10 μ m.Preferably below 5 μ m.
By making mother metal be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, perhaps be ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m, and carry out nitriding treatment under the following conditions, can obtain the skin section tissue behind the above-mentioned nitriding treatment.
Then, creating conditions of steel of the present invention described.
At first, to after being adjusted to steel that predetermined component forms and carrying out rod rolling, carry out warm forging.With the steel of warm forging as mother metal.To the final processing that the steel of warm forging cut etc., make goods.Perhaps, as required the steel of warm forging are implemented the cold-drawn operation, implement high-frequency quenching afterwards, make goods.Perhaps, as required the steel of warm forging are implemented operations such as cutting, implement nitriding treatment afterwards, make goods.
In above-mentioned warm forging operation, in order to make the ferrite particle diameter below 7 μ m, implementing distortion 550～700 ℃ temperature provinces is favourable in the processing more than 1.0.Here, if processing temperature less than 550 ℃, then the tissue still be the worked structure of former state, do not have miniaturization.On the other hand, if processing temperature surpasses 700 ℃, then the crystallization particle diameter surpasses 7 μ m, also can miniaturization.In addition, if the distortion less than 1.0 of amount of finish is then processed insufficiently, low angle boundary has accounted for most, thereby intensity and fatigue strength all can not improve.
After obtaining above-mentioned mother metal tissue, carry out high-frequency quenching, make the skin section sclerosis.The high-frequency quenching condition of this moment can adopt Heating temperature: 800～1000 ℃, frequency: 0.3～400kHz.If Heating temperature is less than 800 ℃, then austenitizing is insufficient, and on the other hand, if surpass 1000 ℃, then the austenite particle diameter becomes thick.In addition, if the not enough 0.3kHz of frequency then can not obtain rapidly and temperature rising fully, on the other hand, if surpass 400kHz, then depth of hardening shoals, and can not improve bending fatigue strength.
After obtaining above-mentioned mother metal tissue, carry out nitriding treatment, make the skin section sclerosis, improve wearability.The nitriding treatment condition of this moment is the temperature range at 500～650 ℃, keeps in nitriding atmosphere 1～100 hour.When carrying out this nitriding treatment, the raw material of nitrogen can be a gas, also can be liquid.
If nitriding temperature is less than 500 ℃, then nitrogen is difficult to enter in the steel, can not get sufficient nitrogenize.On the other hand, if surpass 650 ℃, the then grain growing of restive mother metal, thickization of ferrite crystal grain.In addition, if nitridation time less than 1 hour, because nitrogen do not enter in the steel fully, thereby nitriding result is little, carries out nitriding treatment even surpass 100 hours on the other hand, and its effect is also saturated.
Embodiment 1
To after becoming one-tenth is grouped into shown in the table 1 steel and carrying out rod rolling, under condition as shown in table 2, carry out warm forging, obtain the goods of 60 * 60 * 120mm.From then on take tension test sheet, rotary bending fatigue test sheet and machinability test sheet on the goods.The result that ferrite crystallization particle diameter, the carburizing scale of construction, either pearlite occurred, tensile strength, rotoflector fatigue strength and the machinability of goods are studied is charged to table 2 in the lump.Deflection during warm forging according to limited element analysis technique, is calculated the frictional coefficient of forging plane as 0.3.In addition, following machinability is estimated: if the SC material of the life tools in the external cutting test and JISG5101 is identical or on it, then be marked with zero, if poorer than the SC material, then be marked with *.
As table 2 as can be known, according to the present invention, make and be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, it perhaps is the example of ferrite, cementite and pearlitic structure, can obtain the good intensity of Qiang Du ≧ 1000MPa, and the good fatigue strength of rotoflector Pi labor Qiang Du ≧ 550MPa.
Relative therewith, in the comparative example of the No.6 that the deflection when forging is little, ferrite crystal grain is miniaturization not, and rotoflector fatigue strength is low.In addition, in the comparative example of the low No.7 of forging temperature, tissue becomes worked structure, and in the comparative example of the high No.8 of forging temperature, ferrite crystal grain is miniaturization not on the other hand, so rotoflector fatigue strength is low.
In addition, in the comparative example of the superfluous No.13 of Mo amount, machinability reduces.And in the comparative example of the No.14 of C quantity not sufficient, undercapacity on the other hand, in the comparative example of the No.15 of C surplus, causes machinability to reduce.
Embodiment 2
To after becoming one-tenth is grouped into shown in the table 3 steel and carrying out rod rolling, under condition as shown in table 4, carry out warm forging, obtain the mother metal of 60 * 60 * 120mm.From then on take tension test sheet, rotary bending fatigue test sheet and machinability test sheet on the mother metal.Then, in Heating temperature: under 900 ℃, the condition of frequency: 12kHz the rotary bending fatigue test sheet is carried out high-frequency quenching.The result that the rotoflector fatigue strength of the original austenite crystallization particle diameter of the quenching structure behind the ferrite crystallization particle diameter of mother metal, the carburizing scale of construction, either pearlite occurred, tensile strength, machinability, the high-frequency quenching and the test film behind the high-frequency quenching is studied is charged to table 4 in the lump.Deflection during warm forging according to limited element analysis technique, is calculated the frictional coefficient of forging plane as 0.3.In addition, following machinability is estimated: if the life tools in the external cutting test are identical with common SC material or on it, then be marked with zero, if poorer than the SC material, then be marked with *.
As table 4 as can be known, according to the present invention, make mother metal be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, it perhaps is the example of ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m, can obtain the good intensity of strength of parent more than 1000MPa, and the skin section behind the high-frequency quenching organizes and also becomes the fine martensitic stucture of original austenite particle diameter below 12 μ m, can obtain the tired strong good fatigue strength more than 800MPa of rotoflector.
Relative therewith, if the ferrite particle diameter of mother metal surpasses 7 μ m, then strength of parent deficiency, and the original austenite particle diameter behind the high-frequency quenching is thickization also, and rotoflector fatigue strength is also insufficient.
Particularly in the comparative example of the low No.7 of forging temperature, tissue becomes worked structure, on the other hand, in the comparative example of the high No.8 of forging temperature, the ferrite crystal grain miniaturization.In addition, even so thick ferritic structure is carried out high-frequency quenching, the martensitic original austenite particle diameter that obtains is not also below 12 μ m.
In addition, in the comparative example of the No.12 that does not add Mo, though the miniaturization of mother metal ferrite crystal grain, the original austenite particle diameter behind the high-frequency quenching becomes thick.On the other hand, in the comparative example of the superfluous No.13 of Mo amount, machinability reduces.
And, in the comparative example of the No.14 of C quantity not sufficient, do not quench, on the other hand, in the comparative example of the No.15 of C surplus, cause machinability to reduce.
Embodiment 3
To after becoming one-tenth is grouped into shown in the table 5 steel and carrying out rod rolling, under condition as shown in table 6, carry out warm forging, obtain the mother metal of 60 * 60 * 120mm.From then on take tension test sheet, rotary bending fatigue test sheet and machinability test sheet on the mother metal.Then, under the conditions shown in Table 6 the rotary bending fatigue test sheet is implemented nitriding treatment.The ferrite particle diameter of skin section and the result that rotoflector fatigue strength is studied behind the ferrite crystallization particle diameter of mother metal, the carburizing scale of construction, either pearlite occurred, tensile strength, machinability, the nitriding treatment are charged to table 6 in the lump.Deflection during warm forging according to limited element analysis technique, is calculated the frictional coefficient of forging plane as 0.3.In addition, following machinability is estimated: if the life tools in the external cutting test are identical with common SC material or on it, then be marked with zero, if poorer than the SC material, then be marked with *.
As table 6 as can be known, according to the present invention, make mother metal be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, it perhaps is the example of ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m, can obtain the good intensity of strength of parent more than 1000MPa, and the skin section behind the nitriding treatment organizes and also becomes the micro organization of ferrite particle diameter below 10 μ m, can obtain the good fatigue strength of rotoflector Pi Lao Qiang ≧ 800MPa.In addition, machinability is also good.
Relative therewith, if the ferrite particle diameter of mother metal surpasses 7 μ m, also thickization of the ferrite particle diameter behind the nitriding treatment then, rotoflector fatigue strength is also insufficient.
Particularly in the comparative example of the low No.6 of forging temperature, tissue becomes worked structure, on the other hand, at the high No.7 of forging temperature and in the comparative example of the little No.8 of the deflection when forging, not miniaturization of ferrite crystal grain.In addition, even so thick ferritic structure is carried out nitriding treatment, the ferrite particle diameter in nitrogenize zone is not also below 10 μ m.
In addition, in the comparative example of the No.13 that does not add Mo, though the miniaturization of mother metal ferrite crystal grain, it is big that the ferrite particle diameter behind the nitriding treatment becomes, and rotoflector fatigue strength is insufficient.And in the comparative example of the No.1 of C quantity not sufficient, the ferrite particle diameter behind the nitriding treatment becomes thick, and strength of parent and rotoflector fatigue strength are all insufficient.On the other hand, in the comparative example of the NO.4 of C surplus, cause machinability to reduce.In the comparative example of the No.9 that does not implement nitriding treatment, can not get sufficient rotoflector fatigue strength.
The possibility of utilizing on the industry
According to the present invention, can stablize and had simultaneously following superior strength and fatigue strength High strength steel: strength of parent more than 1000MPa, rotoflector fatigue strength is at 550MPa More than or rotoflector fatigue strength more than 800MPa.
Claims (5)
1. the High Strength Steel of an excellent in fatigue strength, it is characterized in that, contain C:0.3～0.8 quality %, Si:0.01～0.9 quality %, Mn:0.01～2.0 quality % and Mo:0.05～0.6 quality %, surplus is the composition of Fe and unavoidable impurities, be organized as ferrite and the cementite tissue of particle diameter below 7 μ m, perhaps ferrite, cementite and the pearlitic structure of particle diameter below 7 μ m, the skin section behind the high-frequency quenching becomes the martensitic stucture of original austenite particle diameter below 12 μ m.
2. the High Strength Steel of excellent in fatigue strength as claimed in claim 1, it is characterized in that, be selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
3. the High Strength Steel of excellent in fatigue strength as claimed in claim 1 or 2 is characterized in that, the per-cent of organizing of the cementite in the mother metal tissue is more than the 4 volume %.
4. the manufacture method of the High Strength Steel of an excellent in fatigue strength, it is characterized in that, to containing C:0.3～0.8 quality %, Si:0.01～0.9 quality %, Mn:0.01～2.0 quality % and Mo:0.05～0.6 quality %, surplus is the former material of steel of the composition of Fe and unavoidable impurities, implement to be deformed into processing 1.0 or more 550～700 ℃ of temperature provinces, afterwards in Heating temperature: enforcement high-frequency quenching under 800～1000 ℃, frequency: 0.3～400kHz.
5. the manufacture method of the High Strength Steel of excellent in fatigue strength as claimed in claim 4, it is characterized in that the former material of steel is selected from for also containing: Al:0.015～0.06 quality %, Ti:0.005～0.030 quality %, Ni:1.0 quality % are following, Cr:1.0 quality % is following, V:0.1 quality % is following, Cu:1.0 quality % is following, Nb:0.05 quality % is following, Ca:0.008 quality % is following and the composition a kind or 2 kind or more of B:0.004 quality % in following.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP009787/2003 | 2003-01-17 | ||
| JP009784/2003 | 2003-01-17 | ||
| JP2003009795A JP4507494B2 (en) | 2003-01-17 | 2003-01-17 | Method for producing high strength steel with excellent fatigue strength |
| JP009795/2003 | 2003-01-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1701127A CN1701127A (en) | 2005-11-23 |
| CN100469934C true CN100469934C (en) | 2009-03-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2004800010493A Expired - Fee Related CN100469934C (en) | 2003-01-17 | 2004-01-07 | High-strength steel product excelling in fatigue strength and process for producing the same |
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| Country | Link |
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| JP (1) | JP4507494B2 (en) |
| CN (1) | CN100469934C (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5135868B2 (en) * | 2007-04-26 | 2013-02-06 | Ｊｆｅスチール株式会社 | Steel plate for can and manufacturing method thereof |
| KR101181028B1 (en) * | 2007-08-01 | 2012-09-07 | 가부시키가이샤 고베 세이코쇼 | High-strength steel sheet excellent in bendability and fatigue strength |
| KR20140046491A (en) * | 2009-10-22 | 2014-04-18 | 신닛테츠스미킨 카부시키카이샤 | Steel for induction hardening, induction-hardened steel parts, and process for production of same |
| CN102330018A (en) * | 2011-05-31 | 2012-01-25 | 黑龙江建龙钢铁有限公司 | Seamless steel tube used for thick-wall petroleum casing collar material and production method thereof |
| WO2013018893A1 (en) * | 2011-08-03 | 2013-02-07 | 新日鐵住金株式会社 | Untempered steel for hot casting, hot-casted untempered article and method for producing same |
| JP5674620B2 (en) * | 2011-10-07 | 2015-02-25 | 株式会社神戸製鋼所 | Steel wire for bolt and bolt, and manufacturing method thereof |
| JP5316634B2 (en) * | 2011-12-19 | 2013-10-16 | Ｊｆｅスチール株式会社 | High-strength steel sheet with excellent workability and method for producing the same |
| JP5835079B2 (en) * | 2012-04-23 | 2015-12-24 | 新日鐵住金株式会社 | Method for producing ferritic heat resistant steel |
| KR101710816B1 (en) * | 2013-01-31 | 2017-02-27 | 제이에프이 스틸 가부시키가이샤 | Electric resistance welded steel pipe |
| KR101717395B1 (en) * | 2013-04-10 | 2017-03-16 | 신닛테츠스미킨 카부시키카이샤 | Rolled round steel material for steering rack bar, and steering rack bar |
| EP3040435B9 (en) | 2013-08-26 | 2018-03-07 | Nippon Steel & Sumitomo Metal Corporation | Rolled round steel material for steering rack bar, and steering rack bar |
| JP2017122500A (en) * | 2016-01-08 | 2017-07-13 | 株式会社神戸製鋼所 | Large-sized crank shaft |
| KR101802424B1 (en) * | 2016-07-01 | 2017-12-28 | 주식회사 일진글로벌 | Bearing steel and manufacturing method of the same |
| WO2018016504A1 (en) * | 2016-07-19 | 2018-01-25 | 新日鐵住金株式会社 | Steel for induction hardening |
| CN107034413B (en) * | 2016-12-12 | 2018-10-16 | 武汉钢铁有限公司 | The wear-resisting strip of low quenching degree and its manufacturing method |
| CN107475614A (en) * | 2017-09-03 | 2017-12-15 | 安徽天裕汽车零部件制造有限公司 | A kind of automobile cage material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3432950B2 (en) * | 1995-04-17 | 2003-08-04 | 新日本製鐵株式会社 | Steel material for induction hardened shaft parts that has both cold workability and torsional fatigue strength characteristics |
| JPH11181543A (en) * | 1997-12-22 | 1999-07-06 | Nippon Steel Corp | Structural steel excellent in toughness at low temperature and fatigue characteristic, and its production |
| JP3842888B2 (en) * | 1998-01-30 | 2006-11-08 | 新日本製鐵株式会社 | Method of manufacturing steel for induction hardening that combines cold workability and high strength properties |
| JP3394439B2 (en) * | 1998-02-17 | 2003-04-07 | 山陽特殊製鋼株式会社 | Bearing steel with excellent machinability |
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- 2003-01-17 JP JP2003009795A patent/JP4507494B2/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| JP2004263201A (en) | 2004-09-24 |
| JP4507494B2 (en) | 2010-07-21 |
| CN1701127A (en) | 2005-11-23 |
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