CN101287851B - Oil-tempered wire and process for producing the same - Google Patents
Oil-tempered wire and process for producing the same Download PDFInfo
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- CN101287851B CN101287851B CN2006800288972A CN200680028897A CN101287851B CN 101287851 B CN101287851 B CN 101287851B CN 2006800288972 A CN2006800288972 A CN 2006800288972A CN 200680028897 A CN200680028897 A CN 200680028897A CN 101287851 B CN101287851 B CN 101287851B
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Abstract
An oil-tempered wire which, after nitriding, combines high fatigue strength with toughness; and a spring made from the oil-tempered wire. The oil-tempered wire is one having a tempered martensite structure. When this oil-tempered wire is nitrided, a nitride layer having a lattice constant of 2.870-2.890 AA is formed in a surface part of the wire. This oil-tempered wire is obtained by subjecting a steel wire obtained by wire drawing to a quenching step and a tempering step. The quenching step is conducted after heating the wire at 850-950 DEG C in terms of atmosphere temperature for 30-150 sec, excluding 30 sec, while the tempering step is conducted at 400-600 DEG C.
Description
Technical field
The spring that the present invention relates to a kind of oil-tempered wire and method of manufacture thereof and use oil-tempered wire.Relate to a kind of oil-tempered wire especially, it has the high balance of fatigue strength and flexible when steel wire being carried out spring processing and having carried out nitriding treatment.
Background technology
Recently, corresponding with the low oil consumptionization of automobile, the mover of automobile or the miniaturization and of variator are developed.Accompany with it, the stress of the spring institute load that the valve spring of mover or variator are used continues to increase, and employed spring material also seeks to improve fatigue strength, particularly seeks to have the material of fatigue strength and flexible balance.In the spring of the valve spring of these movers or variator, typically use the oil-tempered wire of silicochromium class.
As the technology relevant, have patent documentation 1 and patent documentation 2 described technology with this oil-tempered wire.
Patent documentation 1 relates to the spring steel line, and it discloses a kind of oil-tempered wire, and it is with hold-time: 0.5～30sec, heat-up rate: 50～2000 ℃/when s quenches and the heating during tempering.Thus,, make the carbide shape fibrosis in the crystal grain, thereby make carbide have the function of reinforcing fiber, realize the raising of safe range of stress through with old austenite crystallization particle diameter granular.
On the other hand, patent documentation 2 relates to spring steel, and it discloses a kind of oil-tempered wire, the chemical ingredients that this oil-tempered wire regulation is suitable, stipulated simultaneously specified dimension cementite near-spherical carbide have density.Thus, can realize the high strength of spring steel, in the thermal treatment after rolling, the carbide shape of control in the steel promptly prevents thickization of cementite class carbide and guarantees the characteristic of reeling.
In addition, patent documentation 3 relates to the spring steel line, and it discloses a kind of method, that is, through making in the oil-tempered wire behind the Q-tempering, the ratio of 0.2% endurance and tensile strength is less than or equal to 0.85%, thereby improves the coiling characteristic.In addition, disclose a kind of method, it rises more than or equal to 300MPa 0.2% endurance after oil-tempered wire was heated with 420 ℃ * 20 minutes,
Thereby can improve resistance to fatigue.
Patent documentation 1: the spy opens the 2002-194496 communique
Patent documentation 2: the spy opens the 2002-180196 communique
Patent documentation 3: the spy opens the 2004-315968 communique
Summary of the invention
But, in the related invention of above-mentioned arbitrary document, all be not disclosed in when steel wire carried out spring processing and carried out nitriding treatment, obtain high-fatigue strength and flexible oil-tempered wire.Under the situation that the requirement of safe range of stress high strength uprises, in recent spring is made, steel wire is carried out carrying out nitriding treatment after the spring processing become main flow.Therefore, importantly how to improve the characteristic of the spring behind this nitriding treatment.
At first, in the spring steel line of patent documentation 1 record,, make carbide shape become fibrous and the raising realization safe range of stress through heating hold-time and the heat-up rate in the regulation quenching and tempering operation.Here so-called carbide shape, expression is carried out the state behind the Q-tempering to steel wire, is not actual shape after carrying out spring processing and carrying out nitriding treatment.Under the situation of considering spring characteristic, the state of the carbide behind the nitriding treatment is very important.In addition, observe the method for manufacture of this steel wire, it is characterized in that carrying out the Q-tempering of short period of time; In this method of manufacture; Be difficult to guarantee the toughness of the oil-tempered wire behind the nitriding treatment, be difficult to make the carbide size behind the nitriding treatment to diminish, thereby be difficult to guarantee high-fatigue strength and toughness.Especially,, need to improve the toughness of steel wire in order to improve the safe range of stress of the spring that uses oil-tempered wire, only also insufficient through being controlled at the carbide shape of separating out in the above-mentioned drawing process, need when austenitizing, dissolve not solid solution carbide fully.But, in patent documentation 1, openly be not used to dissolve this not method of solid solution carbide.
On the other hand; In the spring steel of patent documentation 2 records, the characteristic of this method of manufacture only is, except the component that limits steel; Realize high strength in the thermal treatment after rolling and improve toughness, can't expect to improve the safe range of stress of the spring behind the nitriding treatment by this technology.
In addition, in the technology of patent documentation 3 records, any thermal treatment material behavior afterwards that heats for a long time, is suitable for being equivalent to nitrogenize is not disclosed.In view of long-timeization of the nitriding treatment that recently spring is carried out (420 ℃～500 ℃ 1～4 hour down), the material behavior of carrying out after the thermal treatment of longer time is very important.In addition, the important factor of raising safe range of stress is the absolute value of yielding stress (0.2% endurance).Do not have clear and definite record about this point,, be difficult to further improve fatigue characteristic according to the record of patent documentation 3.
The present invention proposes in view of the above problems, and one of its purpose is, a kind of oil-tempered wire and its method of manufacture are provided, and it has high-fatigue strength and toughness concurrently behind nitriding treatment.
In addition, another object of the present invention is, a kind of spring is provided, and it is processed to form the spring that forms as oil-tempered wire is carried out spring, has high-fatigue strength and toughness concurrently.
(oil-tempered wire and spring)
First of oil-tempered wire of the present invention constitutes; A kind of oil-tempered wire with tempered martensite; It is characterized in that; This oil-tempered wire is being carried out under the situation of nitriding treatment, the lattice parameter of the nitride layer that online surface element forms more than or equal to 2.870
and be less than or equal to 2.890
.
In addition; Second of oil-tempered wire of the present invention constitutes; A kind of oil-tempered wire with tempered martensite; It is characterized in that, make with 420 ℃～500 ℃ heating after 2 hours yielding stress and with the yielding stress of this temperature heating after 4 hours, more than or equal to the yielding stress of this temperature heating after 1 hour.
In addition; Spring of the present invention is a kind of oil-tempered wire with tempered martensite to be carried out the spring after the spring processing; It is characterized in that; This spring has the nitride layer that is formed by nitriding treatment at surface element, the lattice parameter of this nitride layer more than or equal to 2.870
and be less than or equal to 2.890
.
Below, illustrate in greater detail oil-tempered wire of the present invention and spring.
(nitriding treatment)
The oil-tempered wire of first formation of the present invention; Behind Q-tempering, compare with current material at lattice parameter, austenite crystallization particle diameter this respect, there is not special difference; But behind nitriding treatment, the lattice parameter of nitride layer and the carbide size that after tempering process, generates have difference.The nitriding treatment here is that gas soft nitriding is handled, and its condition is for being less than or equal to 500 ℃ more than or equal to 420 ℃.The typical nitriding treatment condition of carrying out after this nitriding treatment condition and the spring processing is suitable.In this nitriding treatment condition, the most important thing is temperature.Have following tendency: if the temperature in the nitriding treatment is high, it is big that the lattice parameter of the nitride layer of stating after then becomes, if this temperature is low, then lattice parameter diminishes.Hold-time in the nitriding treatment for example is 2～4 hours.Gas soft nitriding is handled and in mixed atmosphere, is carried out usually, and this mixed atmosphere is in carburizing property gas or nitrogen atmosphere, to add NH
3Gas obtains, this NH
3The addition of gas for example can select normally used 30%～50%.
(nitride layer)
Nitride layer is the hardened layer that forms carbonitride through above-mentioned nitriding treatment at the surface element of oil-tempered wire or spring.Usually the surface hardness of this nitride layer online (spring) is the highest, and hardness is along with reducing to inside.After the lattice parameter stated obtain through X-ray diffraction, this moment X ray to arrive the degree of depth in the sample be about 2～5 μ m.Thus, obtain the scope of the nitride layer of following lattice parameter, for the surface from line (spring) gets into about inner 5 μ m.
(lattice parameter)
The lattice constant of the nitride layer is greater than or equal to 2.870
and less than or equal to 2.890
.Under the situation that steel wire is used as spring, the shear-stress that online surface action is maximum.Thus, for surface hardness is improved, after the processing of reeling, carry out nitriding treatment usually recently.In the alloying element that in steel wire, adds, elements such as Cr, V, Mo become nitride between α-Fe lattice.The fatigure failure of spring is the repeated stress that is applied by the outside and produce slip distortion partial, that concentrate, thereby produces recess and until destruction at the spring near surface.The nitride that between lattice, forms has the effect that suppresses partial slip distortion.
In addition, the nitride that between lattice, forms increases the lattice parameter of α-Fe.Nitride between lattice is many more, and its effect is big more, and lattice parameter is also big more.The result that the inventor studies through great efforts; Obtain following conclusion: if the lattice parameter of nitride layer more than or equal to 2.870
, the then breakthrough raising of safe range of stress.Thus, with the α-Fe lattice parameter of the nitride layer of the oil-tempered wire behind the nitriding treatment (spring) confirm as more than or equal to 2.870
.But if owing to too much form nitride, then toughness descends, thereby safe range of stress descends.Thus, with the upper limit of lattice parameter be defined as 2.890
.Especially; From improving the viewpoint of safe range of stress, preferably this lattice parameter more than or equal to 2.881
and be less than or equal to 2.890
.For obtain more than or equal to 2.881
and be less than or equal to 2.890
lattice parameter, the temperature in the preferred nitriding treatment is less than or equal to 500 ℃ more than or equal to 450 ℃.
The mensuration of this lattice parameter is carried out through X-ray diffraction, but because the surface of oil-tempered wire or spring is a curved surface, so be difficult to correctly measure lattice parameter.So, in the present invention, make the sample after the vertical cutting of the oil-tempered wire (spring) of suitable length, nitriding treatment is carried out in the longitudinal section of this sample, be determined at the lattice parameter of the nitride layer that forms on the longitudinal section.In addition; The lattice parameter of the nitride layer that obtains for the oil-tempered wire that does not carry out spring processing is carried out nitriding treatment and the oil-tempered wire that does not carry out nitriding treatment carried out carrying out after the spring processing lattice parameter of the nitride layer that nitriding treatment obtains is according to there not being the essence differentiated treatment.In addition, spring carries out carrying out shot peening behind the nitriding treatment more.The lattice parameter of the nitride layer of the spring under this situation can use the compressive residual stress of the nitride layer after the shot peening to infer through computing.In addition, also there is the situation of the spring after the shot peening being carried out stress relieving.In this case, consider that in the stress relieving condition of carrying out usually, before and after stress relieving, lattice parameter does not have substantial variation.
(particle diameter of globular carbide)
Oil-tempered wire of the present invention or spring preferably behind nitriding treatment, make the median size of the globular carbide that line inside generates after tempering process be less than or equal to 40nm.Have the not solid solution carbide when quenching heating in the carbide of steel wire and mainly generate the carbide of growing up in the thermal treatment after tempering, the globular carbide here is the latter.If carry out stress relieving annealing or nitriding treatment after the spring processing, thickization of the globular carbide of then after tempering process, separating out meeting, descending appears in the intensity of steel wire, and safe range of stress is descended.Little in carbide size, or under the situation about separating out in a large number, when applying external stress, can carry out transposition action, have the effect that prevents that carbide from piling up.Thus, the average spherical nitride size after the regulation nitrogenize is less than or equal to 40nm.More preferably spherical nitride size is less than or equal to 30nm, and preferred especially spherical nitride size is less than or equal to 20nm.
In addition; The median size of this spherical nitride; Carry out carrying out after the spring processing situation of nitriding treatment for the situation of the oil-tempered wire that does not carry out spring processing being carried out nitriding treatment with to the oil-tempered wire that does not carry out nitriding treatment, according to there not being substantial variations to handle.In addition; Even carry out under the situation of shot peening, stress relieving in order to the spring behind the nitriding treatment; Consider also that under the stress relieving condition of carrying out usually before and after stress relieving, the median size of globular carbide does not have substantial variations.
(being accompanied by the variation of heat treated yielding stress)
In addition, of the present invention second oil-tempered wire that constitute, with 420 ℃～500 ℃ heating after 2 hours yielding stress and with the yielding stress of this temperature heating after 4 hours, more than or equal to the yielding stress of this temperature heating after 1 hour.
In recent years, oil-tempered wire carried out spring processing after, carry out nitriding treatment and become main flow.Through carrying out nitriding treatment, improve surface hardness relevant with maximum stress when using, thereby realize high strength as spring.Existing oil-tempered wire, if apply the thermal treatment suitable with nitriding treatment, then the yielding stress tensile stress descends together along with the treatment time is elongated.That is, promptly under the situation with 420 ℃～500 ℃ of long-time heating steel wires, the inner hardness of steel wire can reduce and soften in the thermal treatment suitable with nitriding treatment, and generation is the destruction of starting point with inside, becomes the low reason of safe range of stress.Because of the repeated stress that the outside applies, produce slip distortion (viscous deformation) partial, that concentrate, thereby cause fatigure failure.In order to prevent above-mentioned situation, need to improve yielding stress.So the yielding stress after carrying out the thermal treatment suitable with nitrogenize is very important.
So; Oil-tempered wire of the present invention has and is carrying out the thermal treatment suitable with nitriding treatment; During promptly 420 ℃～500 ℃ thermal treatment,, be the yielding stress under 1 hour the situation and equal or exceed the treatment time even elongated yielding stress of treatment time can not descend yet.Therefore, using under the situation of this oil-tempered wire as spring, can have high-fatigue strength and toughness concurrently.
Under the situation of the nitriding treatment that carries out the said temperature scope, oil-tempered wire sometimes of the present invention can not find out in 1 hour treatment time that in less than yielding stress descends.On the other hand, the treatment time of common nitriding treatment is 2～4 hours.Therefore, in the present invention, regulation is that 1 hour yielding stress is a benchmark with the treatment time, and the yielding stress of itself and 2 hours and 4 hours is compared.
Especially, preferably with the yielding stress of 420 ℃～500 ℃ heating after 1 hour compare, the yielding stress that heat after 2 hours is higher, and compares with the yielding stress of this temperature heating after 2 hours, and is higher with the yielding stress that this temperature heated after 4 hours.Promptly; Yielding stress when making it become with the processing of carrying out 1 hour is compared; Treatment time is long more, and the oil-tempered wire that yielding stress is high more can be under the situation of the nitriding treatment of the tendency that has long-timeization in recent years; Improve yielding stress, can generate the oil-tempered wire that the excellent more spring of fatigue strength is used.
(other mechanical characteristics)
The oil-tempered wire of second formation of the present invention; Preferably with the tensile strength of 420 ℃～500 ℃ heating after 1 hour compare; Lower with the tensile strength of this temperature heating after 2 hours, and compare with the tensile strength of this temperature heating after 2 hours, lower with the tensile strength of this temperature heating after 4 hours.Through having the tendency of above-mentioned tensile strength, can behind nitriding treatment, obtain H.T., the development of the crackle that can prevent to begin from the fatigure failure starting point or lose by what inclusion caused.
In addition; Tensile strength behind the preferred Q-tempering is more than or equal to 2000MPa; With the yielding stress of 420 ℃～500 ℃ heating after 2 hours more than or equal to 1700MPa; Perhaps the tensile strength behind the Q-tempering is more than or equal to 2000MPa, with the yielding stress of 420 ℃～500 ℃ heating after 2 hours more than or equal to 1750MPa.If known with the yielding stress after the temperature suitable, promptly 420 ℃～500 ℃ heating with nitrogenize more than or equal to 1700N/mm
2, perhaps with the yielding stress after 420 ℃～500 ℃ heating more than or equal to 1750N/mm
2, then safe range of stress can produce breakthrough raising.
In addition, preferably with the pull and stretch value of 420 ℃～500 ℃ heating after 2 hours more than or equal to 35%.If the matrix toughness after the nitrogenize is high, the development of the crackle that then can prevent to begin from the fatigure failure starting point or lost by what inclusion caused can improve safe range of stress.
(chemical ingredients of steel wire)
Oil-tempered wire of the present invention or spring; Preferably contain C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, remainder is made up of Fe and unavoidable impurities.Also can also contain Co:0.02～1.00% with quality %.Also can also contain more than a kind or a kind of selection from the crowd that Ni:0.1～1.0%, Mo:0.05～0.50%, W:0.05～0.15%, Nb:0.05～0.15% and Ti:0.01～0.20% constitutes in addition with quality %.
Each becomes shown in the qualification of component the reasons are as follows.
(C:0.50～0.75 quality %)
C is the important element of intensity of decision steel, if because less than 0.50% then can't obtain sufficient intensity, if surpass 0.75% then loss toughness, so be 0.50～0.75%.
(Si:1.50～2.50 quality %)
Si uses as reductor when the dissolving refining.In addition, have solid solution in ferritic and improve thermotolerance, prevent that thermal treatments such as stress relieving or nitriding treatment after the spring processing from causing the effect of the inner decrease of hardness of line.Because in order to keep thermotolerance, need be more than or equal to 1.5%, if surpass 2.5% toughness reduce, so be 1.50～2.50%.
(Mn:0.20～1.00 quality %)
Mn is identical with Si, and the reductor during as the dissolving refining uses.Therefore, as the necessary addition of reductor, be limited to 0.20% down.In addition, if surpass 1.00%, then when lead bath quenching, generate martensite easily, become the reason that when wire drawing, breaks, institute is so that be limited to 1.00% on it.
(Cr:0.70～2.20 quality %)
Because Cr improves the hardenability of steel, increase the softening resistance of the steel wire behind the Q-tempering, so effectively softening during for the thermal treatments such as temper or nitriding treatment that prevent after the spring processing.In addition, in nitriding treatment, combine to form nitride with the nitrogen element, improve surface hardness, increase lattice parameter simultaneously through the Cr that exists among α-Fe.In addition, when austenitizing, have through forming the effect that carbide makes austenite crystal grain granular.If because less than 0.7% then can't produce effect of sufficient; Institute is so that it more than or equal to 0.7%, if surpass 2.20%, then generates martensite easily when lead bath quenching; Become the reason that when wire drawing, breaks, become the toughness main reasons for decrease that makes after the oil tempering simultaneously.So be defined as 0.70～2.20%.
(Co:0.02～1.00 quality %)
Co strengthens parent phase through being solid-solubilized among α-Fe.Co itself does not form carbide, in addition can multiviscosisty in cementite class carbide yet.Co has to discharge to α-Fe because cementite class carbide is grown up, its diffusion delays and have and suppress the effect that cementite class carbide is grown up.In addition, produce following action: delay martensitic recovery, descend through making Cr and the V solid solution limit in parent phase, and in residual transposition, fine separate out Cr carbide and V carbide.More than or equal to obtaining above-mentioned effect at 0.02% o'clock, because cost uprises, institute is so that be limited to 1.00% on it.
(Ni:0.1～1.0 quality %)
Ni has the erosion resistance of raising and flexible effect, when less than 0.1%, can't tell on, if surpass 1.0%, then not only cost uprises, and also can't produce the effect that improves toughness, so be 0.1～1.0%.
(Mo, V:0.05～0.50 quality %, W, Nb:0.05～0.15 quality %)
These elements form carbide when tempering, have the tendency that increases softening resistance.V, Mo through between the lattice of α-Fe, forming nitride, suppress the slip that repeated stress causes when nitriding treatment, help safe range of stress to improve.But, when less than 0.05%, can't tell on.If Mo, V surpass 0.50%, W, Nb surpass 0.15%, toughness is descended.
(Ti:0.01～0.20 quality %)
Ti forms carbide when tempering, have the effect of the softening resistance that increases steel wire.When less than 0.01%, can't tell on,, can form dystectic non-metallic inclusion TiO, toughness is reduced surpassing at 0.20% o'clock.Therefore be 0.01～0.20%.
(method of manufacture)
On the other hand; The method of manufacture of oil-tempered wire of the present invention is for carrying out lead bath quenching, wire drawing, quenching, tempered method, the category-B type of speed of cooling when being divided into heating means that regulation quenches with category-A type that keeps temperature and tempered condition and regulation lead bath quenching substantially and the heat temperature raising speed when quenching.
At first, the category-A type is described, this category-A type further comprises the A-1 type of utilizing atmosphere heating and quenching the heating and utilizes ratio-frequency heating and the A-2 type of the heating of quenching.
At first; The A-1 type is the method for manufacture of the steel wire after the Wire Drawing being carried out the oil-tempered wire of quenching process and tempering process; Above-mentioned quenching process is carried out after heating, and this heating is to utilize the atmosphere heating, and making temperature is 850 ℃～950 ℃; Make the time be less than or equal to 150sec greater than 30sec, above-mentioned tempering process carries out with 400 ℃～600 ℃.
In the case, preferably tempering process is the 2 stages tempering with first tempering process and second tempering process.The temperature of first tempering process is 400 ℃～470 ℃.Second tempering is carried out with first tempering process with the temperature higher than first tempering continuously.And the temperature that makes second tempering process is 450 ℃～600 ℃.
In addition; The A-2 type is the method for manufacture of the steel wire after the Wire Drawing being carried out the oil-tempered wire of quenching process and tempering process, and above-mentioned quenching process is carried out after heating, and this adds the thermal utilization ratio-frequency heating; Making temperature is 900 ℃～1050 ℃, and making the time is 1sec～10sec.In addition, tempering process is the 2 stages tempering with first tempering process and second tempering process.The temperature of first tempering process is 400 ℃～470 ℃.Second tempering is carried out with first tempering process with the temperature higher than first tempering continuously.And the temperature profile of second tempering process is 450 ℃～600 ℃.
(austenitizing condition)
In the austenitizing of the iron and steel tissue that the heating when quenching is carried out, importantly make not solid solution carbide dissolving and raising toughness, make the austenite crystal grain can not thickization simultaneously.Because if the austenite crystal grain is too small, then the solid solution carbide can be not residual, and the toughness of oil-tempered wire reduces, and safe range of stress reduces, so be preferably more than or equal 3.0 μ m and be less than or equal to 7.0 μ m.Make solid solution carbide not fully dissolve and satisfy the condition of above-mentioned crystallization particle diameter; If atmosphere heating; Then Heating temperature is that 850 ℃～950 ℃, time get final product for being less than or equal to 150sec greater than 30sec; If ratio-frequency heating, then temperature is that 900 ℃～1050 ℃, time are that 1sec～10sec gets final product.This Heating temperature is the design temperature of certain heating unit in atmosphere heating and the ratio-frequency heating.
(tempered condition)
Under the situation that is heated to be the atmosphere heating when quenching, tempering can be under stepless continuous temperature, to carry out with 1 stage, also can carry out with 2 stages.In addition, under the situation that is heated to be ratio-frequency heating when quenching, carry out tempering with 2 stages.
Heating when quenching and carrying out under the tempered situation with 1 stage by atmosphere heating; If 400 ℃ of tempering temperature less thaies, then toughness is not enough owing to can't recover martensite fully, thereby safe range of stress is descended; On the contrary; If tempering temperature surpasses 600 ℃,, thereby safe range of stress is descended then because thickization of carbide and strength degradation.
On the other hand, carry out shown in tempered the reasons are as follows with 2 stages.Carbide precipitation process during tempering has following variation: in 400 ℃～470 ℃, separate out ε-carbide (Fe
2C), in 450 ℃～600 ℃, be changed to cementite class carbide (Fe in addition
3C), if it is with thickization of carbide then become fragile and decrease of hardness is relevant.If making first tempering carries out with 400 ℃～470 ℃ low temperature; At first separate out ε-carbide; Then through the effect of Si or Co etc. in second tempering to the change delay of cementite class carbide, can suppress thickization of the carbide in second tempering process or the nitriding treatment operation.Thus, first tempering is carried out with 400 ℃～470 ℃, second tempering is carried out with 450 ℃～600 ℃, promptly high than first tempering temperature.
If 400 ℃ of the first tempering temperature less thaies, perhaps the second tempering temperature less than is 450 ℃, and then toughness is not enough owing to can't recover martensite fully, thereby safe range of stress is descended.In addition, if first tempering temperature is higher than 470 ℃, perhaps second tempering temperature is higher than 600 ℃, then because thickization of carbide and strength degradation, thereby safe range of stress is descended.Thus, it is 400 ℃～470 ℃ that regulation makes first tempering, and making second tempering is 450 ℃～600 ℃.Especially, under the situation of the heating when quenching, because heat-up rate makes thickization of cementite class carbide soon and easily, so the tempering in 2 stages is more suitable through ratio-frequency heating.
This first tempering and the second tempered temperature head are preferably about 20 ℃～200 ℃.If make this temperature head, then carry out the tempered effect and diminish with 2 stages less than lower value.
The tempered hold-time, for example being about 30～60 seconds under the situation in 1 stage, under the situation in 2 stages, it is about 30～60 seconds that the one the second tempered add up to the hold-time.These hold-times are in order to make oil-tempered wire guarantee that appropriate toughness is necessary.
In addition; The category-B type is the method for manufacture of following oil-tempered wire; It carries out steel wire lead bath quenching operation, the steel wire after the lead bath quenching wire-drawing process and the steel wire after the Wire Drawing carried out quenching process and tempering process; It is characterized in that, arrive when quenching heating in the cooling conditions of (1) lead bath quenching, (2) 600 ℃ heat temperature raising speed, (3) from 600 ℃ to these 3 conditions of the heat-up rate that keeps temperature, satisfy 2 conditions at least.Specifically, further be categorized as following 3 types.
The B-1 type: the lead bath quenching operation does, after with the steel wire austenitizing, through the speed cooling of air cooling with 10 ℃/sec～20 ℃/sec, then, keeps and makes pearlitic transformation with specified temperature.The steel wire that when quenching process, carries out adds to be pined for, make heat temperature raising speed from room temperature to 600 ℃ more than or equal to 20 ℃/sec less than 50 ℃/sec.
The B-2 type: the lead bath quenching operation does, after with the steel wire austenitizing, through the speed cooling of air cooling with 10 ℃/sec～20 ℃/sec, then, keeps and makes pearlitic transformation with specified temperature.The steel wire that when quenching process, carries out adds to be pined for, make from 600 ℃ to the heat-up rate that keeps temperature be 5～20 ℃/sec.
The B-3 type: the steel wire that when quenching process, carries out adds to be pined for, make heat temperature raising speed from room temperature to 600 ℃ more than or equal to 20 ℃/sec less than 50 ℃/sec, from 600 ℃ to the heat-up rate that keeps temperature be 5～20 ℃/sec
(carrying out the cooling conditions behind the austenitizing) through lead bath quenching
Usually lead bath quenching is for piano wire or hard steel line, in order to improve the thermal treatment that wire-drawing workability is implemented through obtaining uniform perlite.In the present invention, make the air cooling that is cooled to behind the austenitizing of lead bath quenching.If carry out air cooling, then can be to make than plumbous stove or the low cost of fluidized-bed.In addition, its speed of cooling is made as 10 ℃/sec～20 ℃/sec, makes the not solid solution carbide solid solution after the quenching through the thickness attenuation with the cementite in the perlite.If the speed of cooling of austenitizing is less than 10 ℃/sec, then the cementite lamella in the perlite is understood thickening, can residual not solid solution carbide after the quenching.In addition, if owing to greater than 20 ℃/sec, then can generate martensite, stringiness reduces, so be the afore mentioned rules scope.
(room temperature～600 before quenching ℃ heat temperature raising speed)
When quenching, heat steel wire in advance.When carrying out this heating, from the temperature-rise period of room temperature to 600 ℃, the cementite in the perlite can balling and thickization.If thickization of cementite can reduce toughness as the solid solution carbide is not residual after then quenching.Here, in order to make the not thickization and lower limit of heat-up rate is made as 20 ℃/sec of cementite.In addition, even because more than or equal to 50 ℃, effect does not have difference yet, so the upper limit is made as less than 50 ℃/sec.
(the heat temperature raising speed of the 600 ℃～maintenance temperature before quenching)
In being accompanied by the temperature-rise period of above-mentioned quenching, if more than or equal to 600 ℃, then the cementite of balling can be to the parent phase solid solution.If make the cementite solid solution fully, then can reduce the not solid solution carbide after the quenching, through strengthening the yielding stress after matrix improves nitriding treatment.Wherein, need delay heat-up rate as much as possible and make not solid solution carbide (cementite) dissolving.Thus, the upper limit of heat-up rate is made as 20 ℃/sec.In addition, owing to be lower than under the situation of 5 ℃/sec at heat-up rate, thickization of austenite crystallization particle diameter meeting is so lower limit is made as 5 ℃/sec.
(other)
Usually, oil-tempered wire obtains through following method: the steel of melting regulation chemical ingredients, and these steel are carried out forge hot, hot rolling and become rolled wire, carry out lead bath quenching, peeling, annealing, Wire Drawing then, quench then, tempering.In this process, can suitably be utilized above-mentioned chemical ingredients by the chemical ingredients of the steel of melting.
In addition, making by oil-tempered wire under the situation of spring, oil-tempered wire is being carried out spring processing, then, for example carrying out low-temperature annealing, nitriding treatment, shot peening, stress relieving in order.
Fig. 1 representes an example of the temperature distribution of making from middle operation to spring in the manufacturing processed of oil-tempered wire.Tempering is carried out here, with first tempering and this 2 stage of second tempering.With first tempering after carry out second tempering continuously, shown in this curve, be meant after first tempering, temporarily do not cool off and proceed second tempering.
The effect of invention
According to oil-tempered wire of the present invention and spring, can have safe range of stress and toughness concurrently.Especially, can generate excellent oil-tempered wire and the spring of safe range of stress behind the nitriding treatment.According to the method for manufacture of oil-tempered wire of the present invention, through the cooling conditions of regulation during lead bath quenching or the intensification condition when quenching heating, or austenitizing condition and the tempered condition of regulation when quenching, can access and have safe range of stress and flexible oil-tempered wire concurrently.
Description of drawings
Fig. 1 is the explanatory view of expression by the temperature distribution of the operation of oil-tempered wire manufacturing spring.
Fig. 2 is the austenitizing condition of the invention material among the expression Test Example 1-2 and has or not the not chart of the relation between the solid solution carbide.
Fig. 3 is the austenitizing condition of the comparative material among the expression Test Example 1-2 and has or not the not chart of the relation between the solid solution carbide.
Fig. 4 is the chart of relation of austenitizing condition and the γ particle diameter of the invention material among the expression Test Example 1-2.
Fig. 5 is the chart of relation of austenitizing condition and the γ particle diameter of the comparative material among the expression Test Example 1-2.
Fig. 6 (A) is that to organize photo, (B) be that the microscope of sample No.2 is organized photo to the microscope of sample No.1.
Fig. 7 is the austenitizing condition of the invention material among the expression Test Example 1-3 and has or not the not chart of the relation between the solid solution carbide.
Fig. 8 is the austenitizing condition of the comparative material among the expression Test Example 1-3 and has or not the not chart of the relation between the solid solution carbide.
Fig. 9 is the chart of relation of austenitizing condition and the γ particle diameter of the invention material among the expression Test Example 1-3.
Figure 10 is the chart of relation of austenitizing condition and the γ particle diameter of the comparative material among the expression Test Example 1-3.
Figure 11 is the chart of relation of tempered condition and the pull and stretch of the invention material among the expression Test Example 1-4-1.
Figure 12 is the chart of relation of tempered condition and the pull and stretch of the comparative material among the expression Test Example 1-4-1.
Figure 13 is the chart of relation of tempered condition and the carbide size of the invention material among the expression Test Example 1-4-1.
Figure 14 is the chart of relation of tempered condition and the carbide size of the comparative material among the expression Test Example 1-4-1.
Figure 15 is the chart of relation of tempered condition and the pull and stretch of the invention material among the expression Test Example 1-5.
Figure 16 is the chart of relation of tempered condition and the pull and stretch of the comparative material among the expression Test Example 1-5.
Figure 17 is the chart of relation of tempered condition and the carbide size of the invention material among the expression Test Example 1-5.
Figure 18 is the chart of relation of tempered condition and the carbide size of the comparative material among the expression Test Example 1-5.
Figure 19 is the explanatory view of the temperature distribution of the expression operation of making oil-tempered wire.
Embodiment
Below, embodiment of the present invention is described.
(embodiment 1)
(1) through the invention material of the chemical ingredients shown in the table 1 and the steel of comparative material are existed
Melting in the vacuum melting stove, forge hot, hot rolling and form the wire rod of
6.5mm.Then, form the steel wire of
3.5mm through this wire rod being carried out lead bath quenching, peeling, annealing, Wire Drawing.When making lead bath quenching is 7 ℃/sec from austenitizing temperature to the speed of cooling that keeps temperature, and the heat-up rate when quenching heating to keeping temperature to be made as 15 ℃/sec, is identical heat-up rate from room temperature.
(2) carry out Q-tempering and form oil-tempered wire through the steel wire that obtains being stated condition later on.Quenching is through after steel wire heating is made the structure of steel austenitizing, in oil, soaks and carries out, and tempering is through carrying out in the lead of the wire rod after will quenching through fusing.
(3) oil-tempered wire that obtains is carried out nitriding treatment.Nitriding treatment is implemented with 420,450,500 ℃ * 2 hours by gas soft nitriding.
(4) to the oil-tempered wire before the nitriding treatment carry out austenite average crystallite particle diameter mensuration, have or not the not affirmation of solid solution carbide and the mensuration of pull and stretch when quenching heating, mensuration, the fatigue test of the carbide size of the oil-tempered wire behind the nitriding treatment being carried out form after the mensuration, tempering process of lattice parameter of nitride layer of Steel Wire Surface.These determination test projects, after in each Test Example of stating, select as required.
(5) austenite average crystallite particle diameter (γ particle diameter) calculates through the process of chopping of regulation among the JIS G 0552.
(6) process of solid solution carbide is to confirm to have or not: the oil-tempered wire behind the Q-tempering is carried out random shooting with TEM (Transmission Electron Microscopy), (the area 40 μ m in 5 visual fields
2/ visual field) though photo in observe one not under the situation of solid solution carbide, think to have not solid solution carbide, under complete unobserved situation, think not solid solution carbide.
(7) pull and stretch is to utilize No. 9 test films of JIS Z 2201 to carry out the tension test based on JIS Z 2241, and the per-cent % that amasss divided by the initial profile of test film through the difference of the initial profile of long-pending A of the smallest cross sectional of the test film that ruptures at this moment and test film being amassed Ao obtains.The target value of pull and stretch is more than or equal to 40%.
(8) mensuration of lattice parameter uses X-ray diffraction device (the RINT1500X ray diffraction device that リ ガ Network company produces) to measure.Usually, in the micrometric measurement of lattice parameter, use the diffraction peak of the high angle side of diffraction angle 2 θ; But because in this example; Behind nitriding treatment, can't obtain clear and definite diffraction peak, can be so use near all diffracted rays 130 degree of low angle side detection.In addition, as standard test specimen, use the Si powder to carry out the angularity correction of diffraction angle.In addition,, be difficult to measure correct lattice parameter,, measure the lattice parameter of the nitride layer in this longitudinal section so nitriding treatment is carried out in the longitudinal section of oil-tempered wire because the surface of oil-tempered wire is a curved surface.
The process of asking for of the size of the carbide that (9) after tempering process, forms is: based on 5 visual fields (the area 2 μ m by the oil-tempered wire of TEM random picture
2/ visual field) photo carries out image analysis, calculates the area of each carbide, and these carbide are regarded as spherical and calculate mean diameter.
(10) process of fatigue test is: after the oil-tempered wire behind the nitriding treatment is implemented shot peening (0.2SB, 20 minutes), carry out stress relieving (230 ℃ * 30 minutes), village's formula rotation bending fatigue test in implementing then.Safe range of stress is 1 * 10
7Inferior, the safe range of stress of target is more than or equal to 1150MPa.
The Chemical Composition of invention material and comparative material is as shown in table 1.Numerical value in the table 1 all is quality %, "
*" represent to be in outside the one-tenth component of regulation in technical scheme 12 of the present invention or 13.
In addition, after state in each Test Example, oil-tempered wire of the present invention behind Q-tempering, aspect lattice parameter, carbide size with comparative material relatively, do not find out notable difference.
Table 1
(Test Example 1-1: atmosphere heating+2 stages tempering)
Use the steel grade of table 1, make the size of the carbide that forms after the lattice parameter, tempering process of the nitride layer under the situation that the gas soft nitriding condition changes and the mensuration of γ particle diameter, study the result of fatigue test simultaneously.Austenitizing condition during quenching is made as, and utilizes atmosphere heating, and making Heating temperature is 900 ℃, and making heat-up time is 90sec, and tempered condition does, as the tempering of 2 stages, first tempering is 430 ℃ * 30sec, and second tempering is 540 ℃ * 30sec.
Test-results is represented in table 2～4.Table 2 expression gas soft nitriding condition is the test-results under 420 ℃ * 2 hours the situation; Table 3 expression gas soft nitriding condition is the test-results under 450 ℃ * 2 hours the situation, and table 4 expression gas soft nitriding condition is the test-results under 500 ℃ * 2 hours the situation.In addition, in table 2～table 4, "
*" represent to be in outside the prescribed condition of technical scheme 1 or 5.
Table 2
Table 3
Table 4
Can know that from these tables the invention material all demonstrates high safe range of stress under any nitriding temperature.On the other hand; Because comparative material K is in 420 ℃, 450 ℃ nitriding treatment, the lattice parameter of nitride layer is less, in 500 ℃ nitriding treatment; The carbide particle diameter is bigger; The lattice parameter of comparative material L, carbide size are all bigger, and the lattice parameter of comparative material M is less, so safe range of stress reduces.In addition, comparative material J, N are owing to produce martensite when lead bath quenching, so can produce the wire drawing broken string, toughness reduces comparative material O because the addition of V is more, thus in Wire Drawing, can produce broken string, so can't implement fatigue test.
(Test Example 1-2: atmosphere heating+2 stages tempering)
Below; For using invention materials A, comparative material K; Make and utilize atmosphere heating and situation that austenitizing condition when quenching changes, research austenitizing condition with have or not the not relation and the fatigue test results of solid solution carbide, austenitizing condition and γ particle diameter.
The austenitizing condition here is: making Heating temperature is 800 ℃, 860 ℃, 900 ℃, 940 ℃, 1000 ℃, and making heat-up time is 10sec, 40sec, 90sec, 140sec, 180sec.Tempering is as the tempering of 2 stages, and making first tempering is 430 ℃ * 30sec, and making second tempering is 540 ℃ * 30sec.The nitriding treatment condition is 450 ℃ * 2 hours.
Expression is invented the austenitizing condition of materials A, comparative material K and is had or not the not relation of solid solution carbide respectively in Fig. 2 and Fig. 3, and materials A, the austenitizing condition of comparative material B and the relation of γ particle diameter are invented in expression respectively in Fig. 4 and Fig. 5.Size, the mensuration of γ particle diameter and the result of fatigue test of the carbide that in addition, expression is carried out sample No.1～10 among Fig. 2,3 forming after the lattice parameter, tempering process of nitride layer in table 5.
Table 5
Its result, the sample No.2,3,4 of invention materials A demonstrates high safe range of stress, sample No.1, the γ particle diameter of solid solution carbide demonstrate low slightly safe range of stress above the sample No.5 of 7.0 μ m but exist not.The equal less than 2.870 of the lattice parameter of any sample of comparative material K
has the safe range of stress that is lower than as the 1150MPa of target.
In addition, the photo that Fig. 6 (A) expression sample No.1 is taken by TEM, the photo that Fig. 6 (B) expression sample No.2 is taken by TEM.Above-mentioned photo all is the photo of the oil-tempered wire tissue behind the nitriding treatment.In the photo of Fig. 6 (A), black round carbide of solid solution not when quenching heating, the little black round in the photo of Fig. 6 (B) is the carbide of separating out in the drawing process.Can know that from the comparison of two photos the solid solution carbide is not far longer than the carbide of in drawing process, separating out, can distinguish two kinds of carbide clearly.
(Test Example 1-3: ratio-frequency heating+2 stages tempering)
Below, for using invention materials A, comparative material K, the situation of utilizing ratio-frequency heating that the austenitizing condition is changed is studied the austenitizing condition and is had or not the not relation and the fatigue test results of solid solution carbide, austenitizing condition and γ particle diameter.
The austenitizing condition is: make Heating temperature be 850 ℃, 910 ℃,, 970 ℃, 1040 ℃, 1100 ℃, making heat-up time is 0.5sec, 2sec, 5sec, 8sec, 20sec.Tempering is as the tempering in 2 stages, and first tempering is 430 ℃ * 30sec, and second tempering is 540 ℃ * 30sec.The nitriding treatment condition is 450 ℃ * 2 hours.
Expression is invented the austenitizing condition of materials A, comparative material K and is had or not the not relation of solid solution carbide respectively in Fig. 7 and Fig. 8, and materials A, the austenitizing condition of comparative material K and the relation of γ particle diameter are invented in expression respectively in Fig. 9 and Figure 10.Size, the mensuration of γ particle diameter and the result of fatigue test of the carbide that in addition, expression is carried out sample No.11～20 among Fig. 7,8 forming after the lattice parameter, tempering process of nitride layer in table 6.
Table 6
Its result, the sample No.12,13,14 of invention materials A demonstrates high safe range of stress, sample No.11, the γ particle diameter of solid solution carbide demonstrate low slightly safe range of stress above the sample No.15 of 7.0 μ m but exist not.The equal less than 2.870 of the lattice parameter of any sample of comparative material K
has the safe range of stress that is lower than as the 1150MPa of target.
(Test Example 1-4-1: atmosphere heating+2 stages tempering)
Below; For using invention materials A, comparative material K; Utilize atmosphere heating to heat and after quenching with 900 ℃ * 90sec; The situation that tempered condition is changed, relation, first tempered condition and the tempering process of studying the one the second tempering temperatures and pull and stretch be the relation of the carbide size of formation afterwards.
Making first tempering temperature is that 350,410,430,460,520 ℃ * 30sec, second tempering temperature are that 420,480,540,590,650 ℃ * 30sec implements.The nitriding treatment condition is 450 ℃ * 2 hours.
Materials A, the tempered condition of comparative material K and the relation of pull and stretch are invented in expression respectively in Figure 11 and Figure 12, and materials A, the tempered condition of comparative material K and the relation of carbide size are invented in expression respectively in Figure 13 and Figure 14.Expression is to sample No.21～30 among Figure 11,12 in table 7, size, γ particle diameter, the mensuration of pull and stretch and the result of fatigue test of the carbide that carries out forming after the lattice parameter, tempering process of nitride layer.
Table 7
Its result, the sample No.22,23,24 of invention materials A demonstrates high safe range of stress, but sample No.21 is because the pull and stretch behind the Q-tempering is lower, so lacking toughness, sample No.25 is because thickization of carbide, thereby has low slightly safe range of stress.Because No.26,27,28,29, the lattice parameter after 30 nitrogenize of comparative material K are less, in addition because the pull and stretch of sample No.26 is lower, thickization of carbide of sample No.30, thus demonstrate lower safe range of stress.
(Test Example 1-4-2: atmosphere heating+1 stage tempering)
Below; For using invention materials A, comparative material K; Utilize atmosphere heating to heat and after quenching with 900 ℃ * 90sec; The situation that tempered condition is changed, size, γ particle diameter, the mensuration of pull and stretch and the result of fatigue test of the carbide that in table 8, forms after the lattice parameter of demonstration nitride layer, the tempering process.
Tempered condition is 350,480,540,590,650 ℃ * 60sec.The nitriding treatment condition is 450 ℃ * 2 hours.
Table 8
Its result, because the pull and stretch behind the sample No.31 Q-tempering of invention materials A is lower, thickization of carbide of sample No.35 is so have low slightly safe range of stress.Lattice parameter after any sample nitrogenize of comparative material K is all less, has the safe range of stress that is lower than as the 1150MPa of target.
(Test Example 1-5: ratio-frequency heating+2 stages tempering)
Below, be illustrated in and use the invention materials A, comparative material K heats with 970 ℃ * 1sec of ratio-frequency heating and after quenching, make the embodiment under the situation that tempered condition changes.
With first tempering temperature is that 350,410,430,460,520 ℃ * 30sec, second tempering temperature are that 420,480,540,590,650 ℃ * 30sec implements.The nitriding treatment condition is 450 ℃ * 2 hours.
Materials A, the tempered condition of comparative material K and the relation of pull and stretch are invented in expression respectively in Figure 15 and Figure 16, and materials A, the tempered condition of comparative material K and the relation of carbide size are invented in expression respectively in Figure 17 and Figure 18.Expression is for sample No.41～50 among Figure 15,16 in table 9, size, γ particle diameter, the mensuration of pull and stretch and the result of fatigue test of the carbide that carries out forming after the lattice parameter, tempering process of nitride layer.
Table 9
Its result, the invention materials A sample No.42,43,44 demonstrate high safe range of stress, but sample No.41 since Q-tempering after pull and stretch lower, so lacking toughness, sample No.45 is owing to thickization of carbide has low slightly safe range of stress.Because No.46,47,48,49, the lattice parameter after 50 nitrogenize of comparative material K are less, the pull and stretch of sample No.46 is lower in addition, thickization of carbide of sample No.50, thereby demonstrate lower safe range of stress.
(Test Example 1-6: spring)
The oil-tempered wire of sample No.2 among Fig. 2 is carried out spring processing, carry out low-temperature annealing then and make spring.The coil mean diameter of this spring is that 20mm, free length are that 50mm, effective turn are 5, and total number of turns is 7.Low-temperature annealing was carried out with 230 ℃ * 20 minutes.Longitudinal section sample by the spring making spring wire that obtains carried out nitriding treatment with the longitudinal section of this sample with 450 ℃ * 2 hours, was determined at the lattice parameter of the nitride layer that forms on this longitudinal section.Simultaneously, also make the longitudinal section sample, carry out nitriding treatment identically, measure the lattice parameter of the nitride layer that obtains by the oil-tempered wire that does not carry out spring processing.Its result; Arbitrarily lattice parameter all be in more than or equal to 2.870
and be less than or equal to 2.890
scope in, and two lattice parameters do not have evident difference.
(embodiment 2)
(1) forms the wire rod of
6.5mm through steel melting in the vacuum melting stove, forge hot, hot rolling to invention material shown in the above-mentioned table 1 and comparative material.Then; Carry out lead bath quenching through stating condition later on, carry out peeling, annealing, Wire Drawing then and form the steel wire of
3.5mm.
(2) condition is carried out lead bath quenching, Q-tempering forms oil-tempered wire through the steel wire that obtains is stated later on.Quenching is through after steel wire heating is made the structure of steel austenitizing, and (room temperature) soaked and carried out in oil, and tempering is through carrying out in the lead of the wire rod after will quenching through fusing.
(3) then, to be equivalent to 420,450,500 ℃ * 1,2,4 hour of nitriding treatment condition, oil-tempered wire is heat-treated.
(4) oil-tempered wire before the imaginary nitrogenize thermal treatment is carried out the mensuration of austenite average crystallite particle diameter, has or not the not affirmation of solid solution carbide when quenching heating, carrying out the mensuration and the fatigue test of the carbide size that oil-tempered wire after this thermal treatment carries out forming after the mensuration, tempering process of yielding stress, tensile strength and pull and stretch.In addition, oil-tempered wire is carried out nitriding treatment, measure the lattice parameter of the nitride layer on line surface.
(5) yielding stress, tensile strength are measured based on JIS Z 2241.Yielding stress is through tension set stress determination method, and making permanent extension is 0.2% to calculate.The target value of pull and stretch is 35%.
(6) process of solid solution carbide is to confirm to have or not: the oil-tempered wire behind the Q-tempering is carried out random shooting with TEM, (the area 40 μ m in 5 visual fields
2/ visual field) though photo in observe one not under the situation of solid solution carbide; Think and have not solid solution carbide; Under the situation of its mean diameter more than or equal to 200nm, be evaluated as *, be evaluated as △ more than or equal to 100nm under the situation less than 200nm, under complete unobserved situation; Thinking does not have not solid solution carbide, is evaluated as zero.
(7) process of fatigue test is: behind Q-tempering; To carry out imaginary nitrogenize thermal treatment in 420,450,500 ℃ * 1,2,4 hour; After implementing shot peening (0.2SB, 20 minutes) then; Carry out stress relieving (230 ℃ * 30 minutes), village's formula rotation bending fatigue test in implementing then.Safe range of stress is 1 * 10
7Inferior, make target more than or equal to 1150MPa.
(8) carbide size, the lattice parameter that form after austenite average crystallite particle diameter, pull and stretch, the tempering process are to obtain with embodiment 1 identical method.
(embodiment 2-1: the lead bath quenching condition and the preceding heat-up rate 1 that quenches)
According to temperature distribution shown in Figure 19, all the components shown in the his-and-hers watches 1 is made oil-tempered wire with following condition." speed of cooling A " among Figure 19 is " speed of cooling in lead bath quenching behind the austenitizing "; " heat-up rate A " among this figure be " the heat temperature raising speed before quenching (room temperature～600 ℃) ", and " the heat-up rate B " among this figure is " the preceding heat temperature raising speed of quenching (600～maintenance temperature) ".The test-results that the oil-tempered wire that obtains is carried out above-mentioned each assessment item is shown in table 10～table 18.In these tables, comparative material J, N produce the wire drawing broken string owing to when lead bath quenching, produce martensite, and toughness reduces comparative material O because the addition of V is more, thus in Wire Drawing, produce broken string, thereby can't obtain oil-tempered wire.
(creating conditions)
Austenitizing condition in the lead bath quenching: 900 ℃ * 60sec
Speed of cooling in the lead bath quenching behind the austenitizing: 15 ℃/sec
Constant temperature phase change conditions: 650 ℃ * 60sec
Heat temperature raising speed before quenching (room temperature～600 ℃): 20 ℃/sec
Heat temperature raising speed before quenching (600～maintenance temperature): 10 ℃/sec
Quenching conditions: atmosphere heating 900 ℃, 90sec
Tempered condition: 430 ℃ * 30sec → 540 ℃ * 30sec (2 stage)
Nitridation conditions: 420,450,500 ℃ * 1,2,4 hour (gas soft nitriding)
Table 10
420 ℃ * 1 hour
[0199]Table 11
420 ℃ * 2 hours
Table 12
420 ℃ * 4 hours
[0205]Table 13
450 ℃ * 1 hour
Table 14
450 ℃ * 2 hours
[0211]Table 15
450 ℃ * 4 hours
Table 16
500 ℃ * 1 hour
[0217]Table 17
500 ℃ * 2 hours
Table 18
500 ℃ * 4 hours
(result)
The invention material of A～I all satisfies yielding stress and the target value of pull and stretch after the carbide size that forms after lattice parameter after the nitrogenize, the quenching process, austenite crystallization particle diameter, the imaginary nitrogenize heat treated, and safe range of stress also demonstrates more than or equal to the 1150MPa as target.
On the other hand, the yielding stress after the lattice parameter after comparative material K, the M nitrogenize, the imaginary nitrogenize heat treated is lower, and comparative material L is owing to bigger, the residual not solid solution of the lattice parameter carbide after the nitrogenize, so safe range of stress descends.
(Test Example 2-2: the lead bath quenching condition and the preceding heat-up rate 2 that quenches)
Use the invention materials A and the comparative material K of table 1, make the cooling conditions behind the austenitizing in the lead bath quenching, preceding heat temperature raising speed, the variation shown in table 19 of Q-tempering condition of quenching, make oil-tempered wire.Then, carry out nitriding treatment with 450 ℃ * 2 hours, implement shot peening (0.2SB, 20 minutes) then after, carry out stress relieving (230 ℃ * 30 minutes), village's formula rotation bending fatigue test in implementing then.Its result is shown in table 20, table 21.In these tables, there not be in 4,10,14 the reason of the condition of record except that the lead bath quench cooling rate to be creating conditions, generation martensite when lead bath quenching and can't carry out pearlitic transformation rightly breaks when wire drawing.In addition, "
*" represent to be in outside the specialized range of the present invention, the hold-time of tempering temperature is: 1 stage: 60sec, 2 stages: each 30sec.
Table 19
[0230]Table 20 invention materials A
[0232]Table 21 comparative material K
Can know from table 20,21; In the invention materials A; Create conditions and 1～20 all satisfy carbide size, the yielding stress after the imaginary nitrogenize heat treated and the target value of pull and stretch that forms after lattice parameter after the nitrogenize, the quenching process, safe range of stress also demonstrates high value.
21 make γ crystallization thickization of particle diameter and yielding stress decline owing to create conditions, thus the 22 residual not solid solution carbide of creating conditions, and its mean diameter is above 200nm, so the toughness of matrix descends and the safe range of stress reduction.
Because the lattice parameter of comparative material K after all making nitrogenize under any condition diminishes; And in thickization of γ crystallization particle diameter in 21 of creating conditions; Yielding stress descends; The 22 residual not solid solution carbide so create conditions, and its mean diameter surpasses 200nm, the result that safe range of stress reduces so produce the toughness decline of matrix.
With reference to reaching specific embodiment in detail the present invention has been described, but for a person skilled in the art, can easily under the situation that does not break away from the spirit and scope of the present invention, have carried out various changes and modification.
In addition, the application proposes based on the Japanese patent application (the special 2005-248468 of hope) of the Japanese patent application (the special 2005-228859 of hope) of on August 5th, 2005 application and application on August 29th, 2005, and foregoing is introduced this paper as a reference.
The industry usability
Oil-tempered wire of the present invention can use in the manufacturing that requires fatigue strength and flexible spring etc.
In addition, the method for manufacture of oil-tempered wire of the present invention can be utilized in the manufacturing field that requires fatigue strength and flexible oil-tempered wire.
In addition, spring of the present invention can suitably be used for the valve spring of motor car engine or the spring of variator etc.
Claims (7)
1. the method for manufacture of an oil-tempered wire, its steel wire after to Wire Drawing carries out quenching process and tempering process, it is characterized in that,
Above-mentioned quenching process is carried out after heating, and this heating is to utilize the atmosphere heating, and making temperature is 850 ℃～950 ℃, makes the time be less than or equal to 150sec greater than 30sec,
Above-mentioned tempering process carries out with 400 ℃～600 ℃,
Wherein, above-mentioned oil-tempered wire contains C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, and remainder is made up of Fe and unavoidable impurities,
Above-mentioned tempering process has first tempering process and second tempering process, and this second tempering is carried out with first tempering process with the temperature higher than first tempering continuously,
The temperature of first tempering process is 400 ℃～470 ℃, and the temperature of second tempering process is 450 ℃～600 ℃.
2. the method for manufacture of an oil-tempered wire, its steel wire after to Wire Drawing carries out quenching process and tempering process, it is characterized in that,
Above-mentioned quenching process is carried out after heating, and this heating is to utilize ratio-frequency heating, and making temperature is 900 ℃～1050 ℃, and making the time is 1sec～10sec,
Above-mentioned tempering process has first tempering process and second tempering process, and this second tempering is carried out with first tempering process with the temperature higher than first tempering continuously,
The temperature of first tempering process is 400 ℃～470 ℃, and the temperature of second tempering process is 450 ℃～600 ℃,
Wherein, above-mentioned oil-tempered wire contains C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, and remainder is made up of Fe and unavoidable impurities.
3. the method for manufacture of an oil-tempered wire, its carry out steel wire lead bath quenching operation, the steel wire after the lead bath quenching wire-drawing process and to the quenching process and the tempering process of the steel wire after the Wire Drawing, it is characterized in that,
Above-mentioned lead bath quenching operation does, after with the steel wire austenitizing,, then, keeps and makes pearlitic transformation with the temperature of regulation through the speed cooling of air cooling with 10 ℃/sec～20 ℃/sec,
The steel wire that when above-mentioned quenching process, carries out adds to be pined for, make heat temperature raising speed from room temperature to 600 ℃ more than or equal to 20 ℃/sec less than 50 ℃/sec,
Wherein, above-mentioned oil-tempered wire contains C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, and remainder is made up of Fe and unavoidable impurities.
4. the method for manufacture of an oil-tempered wire, its carry out steel wire lead bath quenching operation, the steel wire after the lead bath quenching wire-drawing process and to the quenching process and the tempering process of the steel wire after the Wire Drawing, it is characterized in that,
Above-mentioned lead bath quenching operation does, after with the steel wire austenitizing,, then, keeps and makes pearlitic transformation with the temperature of regulation through the speed cooling of air cooling with 10 ℃/sec～20 ℃/sec,
The steel wire that when above-mentioned quenching process, carries out adds to be pined for, make from 600 ℃ to the heat-up rate that keeps temperature be 5 ℃/sec～20 ℃/sec,
Wherein, above-mentioned oil-tempered wire contains C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, and remainder is made up of Fe and unavoidable impurities.
5. the method for manufacture of an oil-tempered wire, its carry out steel wire lead bath quenching operation, the steel wire after the lead bath quenching wire-drawing process and to the quenching process and the tempering process of the steel wire after the Wire Drawing, it is characterized in that,
The steel wire that when above-mentioned quenching process, carries out adds to be pined for, make heat temperature raising speed from room temperature to 600 ℃ more than or equal to 20 ℃/sec less than 50 ℃/sec, make from 600 ℃ to the heat-up rate that keeps temperature be 5 ℃/sec～20 ℃/sec,
Wherein, above-mentioned oil-tempered wire contains C:0.50～0.75%, Si:1.50～2.50%, Mn:0.20～1.00%, Cr:0.70～2.20%, V:0.05～0.50% with quality %, and remainder is made up of Fe and unavoidable impurities.
6. according to the method for manufacture of any described oil-tempered wire in the claim 1 to 5, it is characterized in that,
Above-mentioned oil-tempered wire also contains Co:0.02～1.00% with quality %.
7. according to the method for manufacture of any described oil-tempered wire in the claim 1 to 5, it is characterized in that,
Above-mentioned oil-tempered wire also with quality % contain from Ni:0.1～1.0%, Mo:0.05～0.50%, W:0.05～0.15%, Nb:0.05～0.15%, and the crowd that constitutes of Ti:0.01～0.20% select more than a kind or a kind.
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| JP2005228859 | 2005-08-05 | ||
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| JP248468/2005 | 2005-08-29 | ||
| JP2005248468A JP2007063584A (en) | 2005-08-05 | 2005-08-29 | Oil tempered wire and manufacturing method therefor |
| PCT/JP2006/314907 WO2007018048A1 (en) | 2005-08-05 | 2006-07-27 | Oil-tempered wire and process for producing the same |
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| CN101287851B true CN101287851B (en) | 2012-09-05 |
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| CN110983192A (en) * | 2019-12-18 | 2020-04-10 | 上海材料研究所 | High-performance fastener elastic strip and manufacturing method and application thereof |
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| CN103131834B (en) * | 2011-11-25 | 2015-03-25 | 上海中国弹簧制造有限公司 | Spring steel wire processing process for increasing fatigue performance of high strength spring steel wire |
| JP6497898B2 (en) * | 2014-11-19 | 2019-04-10 | 日本発條株式会社 | Leaf spring device and production method of leaf spring device |
| KR101745192B1 (en) * | 2015-12-04 | 2017-06-09 | 현대자동차주식회사 | Ultra high strength spring steel |
| JP6617922B2 (en) * | 2016-03-22 | 2019-12-11 | 住友電気工業株式会社 | Oil tempered wire |
| WO2018107473A1 (en) * | 2016-12-16 | 2018-06-21 | 蔡赛 | Annealing and heat treatment method for steel wire |
| CN108676973A (en) * | 2018-06-08 | 2018-10-19 | 铃木加普腾钢丝（苏州）有限公司 | A kind of method of oil-temper spring steel wire destressing |
| US11952650B2 (en) | 2019-10-16 | 2024-04-09 | Nippon Steel Corporation | Steel wire |
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| WO2021075501A1 (en) | 2019-10-16 | 2021-04-22 | 日本製鉄株式会社 | Valve spring |
| MX2022010291A (en) | 2020-02-21 | 2022-10-13 | Nippon Steel Corp | Steel wire. |
| JP7321354B2 (en) * | 2020-02-21 | 2023-08-04 | 日本製鉄株式会社 | valve spring |
| CN115298339B (en) * | 2020-02-21 | 2023-10-24 | 日本制铁株式会社 | Shock absorber spring |
| CN113416834A (en) * | 2021-01-26 | 2021-09-21 | 陈冬英 | Steel wire heat treatment quenching process |
| CN114875213A (en) * | 2022-04-14 | 2022-08-09 | 徐州徐工传动科技有限公司 | Quenching and tempering and nitriding process method for 42CrMo ring gear |
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| JP2003306747A (en) * | 2002-04-16 | 2003-10-31 | Sumitomo Denko Steel Wire Kk | Steel wire and production method therefor, and spring |
| JP2005120479A (en) * | 2004-10-25 | 2005-05-12 | Togo Seisakusho Corp | High strength spring and production method therefor |
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| JP2003213372A (en) * | 2002-01-25 | 2003-07-30 | Sumitomo Denko Steel Wire Kk | Steel wire for spring and spring |
| JP2004190116A (en) * | 2002-12-13 | 2004-07-08 | Sumitomo Denko Steel Wire Kk | Steel wire for spring |
| JP4097151B2 (en) * | 2003-03-28 | 2008-06-11 | 株式会社神戸製鋼所 | High strength spring steel wire and high strength spring with excellent workability |
| JP2004315967A (en) * | 2003-03-28 | 2004-11-11 | Kobe Steel Ltd | Steel for spring having excellent settling resistance and fatigue property |
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| JP2003306747A (en) * | 2002-04-16 | 2003-10-31 | Sumitomo Denko Steel Wire Kk | Steel wire and production method therefor, and spring |
| JP2005120479A (en) * | 2004-10-25 | 2005-05-12 | Togo Seisakusho Corp | High strength spring and production method therefor |
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| CN110983192A (en) * | 2019-12-18 | 2020-04-10 | 上海材料研究所 | High-performance fastener elastic strip and manufacturing method and application thereof |
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