WO2012133885A1 - Ressort et procédé de production associé - Google Patents

Ressort et procédé de production associé Download PDF

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Publication number
WO2012133885A1
WO2012133885A1 PCT/JP2012/058876 JP2012058876W WO2012133885A1 WO 2012133885 A1 WO2012133885 A1 WO 2012133885A1 JP 2012058876 W JP2012058876 W JP 2012058876W WO 2012133885 A1 WO2012133885 A1 WO 2012133885A1
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Prior art keywords
spring
residual stress
compressive residual
shot peening
point
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PCT/JP2012/058876
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English (en)
Japanese (ja)
Inventor
真平 黒川
鈴木　健
芳樹 小野
典利 高村
文男 山本
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日本発條株式会社
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Publication of WO2012133885A1 publication Critical patent/WO2012133885A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F35/00—Making springs from wire
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/10—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
    • C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite

Definitions

  • the present invention relates to a spring having a high compressive residual stress layer and a manufacturing method thereof.
  • valve spring materials for automobile engines are JIS standards such as carbon steel oil temper wire (SWO-V), Cr-V steel oil temper wire (SWOCV-V), Si-Cr steel oil temper wire (SWOSC-V), etc.
  • Si—Cr steel oil tempered wires have been widely used from the viewpoint of fatigue resistance and sag resistance.
  • JIS standard oil tempered wires have significantly increased notch susceptibility to defects such as wrinkles or inclusions, which can cause breakage during cold spring forming (coiling) and brittleness during use.
  • the tendency to show a typical form of destruction is a problem.
  • the spring has a tensile residual stress after coiling in the direction of compressive external force during coiling, and a compressive residual stress after coiling in the direction of tensile external force during coiling. These residual stress values tend to increase.
  • One means for this is to apply compressive residual stress that is high and deep inside the surface of the wire.
  • fatigue resistance is widely improved by applying compressive residual stress to the surface layer of the wire by shot peening.
  • by increasing the compressive residual stress of the surface layer by shot peening it is possible to reduce early breakage starting from the surface.
  • the yield strength of the strand increases with increasing hardness, the amount of plastic strain on the surface layer given by shot peening decreases, and the region where compressive residual stress remains (the compressive residual stress becomes zero from the surface of the strand) It is difficult to form a thick (distance in the depth direction to the position).
  • the following methods have been proposed.
  • Patent Document 1 describes a spring having excellent fatigue resistance manufactured using an oil temper steel material in which an element such as V is added to a chemical component of JIS standard steel.
  • an element such as V
  • these additive elements increase the toughness of the steel material by refining crystal grains and contribute to the improvement of fatigue resistance, but the material cost increases.
  • nitriding is expected to improve fatigue resistance due to an increase in surface hardness, it is necessary to completely remove the iron nitride of the surface layer that can cause a decrease in fatigue strength after nitriding treatment, so the manufacturing process becomes complicated, In addition, the nitriding cost is high, resulting in high cost.
  • An object of the present invention is to provide a spring having a high compressive residual stress layer with improved fatigue resistance and a manufacturing method thereof, while reducing the material cost and simplifying the manufacturing process.
  • the present inventors have conducted intensive research on the fatigue strength of high-strength valve springs.
  • the residual stress generated after coiling can be reduced to some extent by adjusting the steel composition and subsequent annealing conditions, but it is fundamentally difficult to eliminate the effect on fatigue strength while maintaining the high strength of the steel. It came to the idea that there was. Therefore, it has been considered that it is effective to substantially reduce the residual stress generated by coiling by heating the coiled spring to the austenitizing temperature.
  • the fatigue resistance of the base material itself is improved by performing austempering treatment on the spring heated to the austenitizing temperature and making the structure excellent in balance between strength, ductility and toughness. .
  • the retained austenite on the wire surface layer is transformed into martensite by processing-induced transformation by subsequent setting and shot peening.
  • a compressive residual stress layer reaching deep inside was formed due to volume expansion, and the progress of fatigue cracks could be suppressed and fatigue resistance could be improved.
  • compressive residual stress can be applied to the deeper interior than shot peening, preventing fatigue failure starting from the interior, and fatigue resistance. It was found that can be improved.
  • the compressive residual stress on the strand surface is impaired.
  • the compressive residual stress on the surface of the strand can be recovered by performing shot peening after the usual setting at the end of the spring manufacturing process.
  • this shot peening can remove the microcracks that have occurred in the previous process and improve the surface properties, thus preventing fatigue failure starting from microcracks on the surface and improving fatigue resistance. I found out that I could do it.
  • a low-priced material such as a JIS standard oil tempered wire or a hard-drawn wire of the same composition can be used as a material before coiling, and a complicated setting heat treatment such as quenching and tempering is not used, and normal setting and shot peening are performed. It has been found that a spring having a high compressive residual stress layer can be produced by using it. In addition, the manufacturing cost can be reduced by omitting the conventional nitriding treatment.
  • the manufacturing method of the spring of the present invention is, in mass%, C: 0.5 to 0.7%, Si: 1.0 to 2.0%, Mn: 0.1 to 1.0%, Cr: 0.1 to 1.0%, P: 0.035% or less, S: 0.035% or less, a forming step of forming a spring material into a steel material having a component composed of iron and inevitable impurities, and Ac3 After austenitizing at a temperature of point to (Ac3 point + 250 ° C.), it is cooled at a rate of 20 ° C./second or more and kept isothermal at a temperature of (Ms point ⁇ 20 ° C.) to (Ms point + 60 ° C.) for 400 seconds or more. Next, a heat treatment step for cooling to room temperature at a cooling rate of 20 ° C./second or more, a setting step for imparting permanent strain, and a shot peening step for projecting shots are performed in order.
  • the spring of the present invention is, in mass%, C: 0.5 to 0.7%, Si: 1.0 to 2.0%, Mn: 0.1 to 1.0%, Cr: 0.1 Up to 1.0%, P: 0.035% or less, S: 0.035% or less, the balance having a component composed of iron and inevitable impurities, and in any cross section, bainite is 65% or more in area ratio, It has a structure in which the retained austenite is 4 to 13% and the balance (including 0%) is martensite, and the average carbon concentration in the retained austenite is 0.65 to 1.7%.
  • the compressive residual stress on the surface is 900 to 2000 MPa, the compressive residual stress at a position of 0.3 mm from the surface is 200 MPa or more, and the average Vickers hardness of the core is 550 to 650 HV in an arbitrary cross section. It is characterized by.
  • the equivalent-circle diameter of the cross section of the strand is 1.5 to 5.0 mm.
  • the spring of the present invention is preferably a coil spring. In addition, you may use the spring of this invention for a stabilizer, a leaf
  • a steel wire having a spring steel composition of JIS standard that does not contain an expensive alloying element and is easily available can be highly compressed on the surface layer of the wire without complicated heat treatment and surface hardening treatment.
  • a spring having a residual stress layer and excellent in fatigue resistance can be obtained.
  • the amount of alloying elements is small, the recyclability is excellent, the manufacturing process can be simplified, and the productivity can be improved and the energy can be saved by shortening the processing time.
  • C 0.5-0.7%
  • C is an important element for securing a desired high strength and for obtaining a desired retained austenite ratio at room temperature, and it is necessary to contain 0.5% or more.
  • the C concentration is excessive, the ratio of retained austenite, which is a soft phase, is excessively increased and it becomes difficult to obtain a desired strength. Therefore, the C content is 0.5 to 0.7%.
  • Si 1.0-2.0%
  • bainitic ferrite is generated by isothermal holding, and C is discharged into the austenite.
  • a retained austenite having a high C concentration can be obtained.
  • Si has an effect of suppressing the formation of carbides when C is discharged from bainitic ferrite into austenite, and is an indispensable element for obtaining high C concentration retained austenite as defined in the present invention.
  • Si is an element contributing to solid solution strengthening, and is an effective element for obtaining high strength. In order to obtain these effects, Si is contained by 1.0% or more. However, if the amount of Si is excessive, the ratio of soft retained austenite is increased, and conversely, the strength is decreased, so the content is suppressed to 2.0% or less. For this reason, the Si content is set to 1.0 to 2.0%.
  • Mn 0.1 to 1.0%
  • Mn is added as a deoxidizing element, but is also an element that stabilizes austenite. It is desirable to contain 0.1% or more in order to obtain retained austenite specified in the present invention.
  • the Mn content is set to 0.1 to 1.0%.
  • ⁇ Cr 0.1-1.0% Cr is an element that can enhance the hardenability of the steel material and facilitate high strength. Moreover, since it also has an effect of delaying pearlite transformation and can stably obtain a bainite structure (suppress pearlite structure) at the time of cooling after austenitizing heating, it is contained in an amount of 0.1% or more. However, if it is excessively contained exceeding 1.0%, iron carbide tends to be generated, and retained austenite is hardly generated, so that it is suppressed to 1.0%. Therefore, the Cr content is set to 0.1 to 1.0%.
  • P 0.035% or less and S: 0.035% or less Since P and S are elements that promote grain boundary segregation due to grain boundary segregation, the content is preferably low, and the upper limit is 0.035. %. Preferably, it is 0.01% or less.
  • the forming process is a process of forming a steel material into a desired shape, and is preferably coiling.
  • molding is not specifically limited, In order to suppress manufacturing cost, the cold forming normally performed is preferable.
  • a forming method a method using a spring forming machine (coiling machine), a method using a cored bar, or the like may be used.
  • the formed steel is austenitized and kept isothermal, and then cooled.
  • the structure of the steel material before austenitization is not particularly limited. For example, it is possible to use a strip steel material that has been hot forged or drawn.
  • the austenitizing temperature needs to be from Ac3 point to (Ac3 point + 250 ° C.). If it is less than Ac3 point, it does not become austenite and it becomes difficult to obtain a desired bainite ratio. Moreover, when it exceeds (Ac3 point +250 degreeC), a prior-austenite particle size will become easy to coarsen and there exists a possibility of causing a fall of ductility.
  • a cooling rate of 20 ° C./s or higher, preferably 50 ° C./s or higher.
  • the cooling rate is less than 20 ° C./s, pearlite is generated during cooling, making it difficult to obtain a desired structure.
  • the temperature for isothermal holding needs to be (Ms point ⁇ 20 ° C.) to (Ms point + 60 ° C.), which is a very important control factor for obtaining a desired structure. If it is less than (Ms point ⁇ 20 ° C.), a lot of martensite is generated in the early stage of transformation, so that the improvement of ductility is hindered and it becomes difficult to obtain a desired bainite ratio. On the other hand, when it exceeds (Ms point + 60 ° C.), the tensile strength is lowered, so that the strength is lowered. In addition, the time for performing isothermal holding needs to be 400 seconds or more, which is also a very important control factor.
  • the cooling rate after isothermal holding is preferably as fast as possible to obtain a uniform structure.
  • a cooling rate of 20 ° C./s or higher is required, and preferably 50 ° C./s or higher. Specifically, oil cooling or water cooling is good.
  • the cooling rate is less than 20 ° C./s, a structure (such as pearlite) other than the structure defined in the present invention is generated.
  • the -Setting process Setting is performed in order to significantly improve the elastic limit and reduce permanent deformation by applying plastic strain. Further, by performing setting at 200 to 300 ° C. (warm setting), the sag resistance can be further improved.
  • the shear strain acting on the surface of the spring wire is preferably 0.0190 to 0.0220. This is an important control factor for obtaining a thick and high compressive residual stress. If the shear strain acting on the surface of the strand during setting is less than 0.0190, a sufficient compressive residual stress layer cannot be obtained, and a compressive residual stress at a position of 0.3 mm from the surface defined in the present invention can be obtained. Can not. Further, if it exceeds 0.0220, a pre-crack is generated in the surface layer of the wire, the crack progresses at the time of use, and there is a high possibility that it breaks earlier than the desired life.
  • Shot peening is a process in which a shot made of metal or the like is collided with a spring to impart a compressive residual stress to the surface, thereby significantly improving the fatigue resistance of the spring.
  • the residual stress generated by the molding is substantially zero after the heat treatment step, and a compressive residual stress layer that is high and deep inside the spring wire surface can be formed by shot peening.
  • the shot peening process is preferably performed a plurality of times, and the sphere equivalent diameter of the shot used in the shot peening process performed later is preferably smaller than the sphere equivalent diameter of the shot used in the shot peening process performed earlier. Thereby, the surface roughness increased by the shot peening performed previously can be reduced. Moreover, it is preferable to perform one or more shot peening processes before the setting process.
  • high-hardness particles such as cut wires, steel balls, and FeCrB can be used.
  • the compressive residual stress can be adjusted by a shot equivalent sphere diameter, a projection speed, a projection time, and a multi-stage projection method.
  • Bainite 65% or more Bainite is a metal structure obtained by isothermal transformation of austenitic steel at a low temperature, and is composed of bainitic ferrite and iron carbide. Since the base bainitic ferrite has a high dislocation density and the iron carbide has a precipitation strengthening effect, the strength can be increased with a bainite structure. Furthermore, the bainite structure of the present invention is a structure in which iron carbide is finely precipitated on the bainitic ferrite matrix, and the decrease in grain boundary strength is small, and the decrease in ductility and toughness is small even when the strength is high. Thus, bainite is an indispensable structure for obtaining high strength and high ductility. And in order to obtain a desired high strength and high ductility, bainite needs 65% or more by area ratio.
  • untransformed austenite in isothermal holding becomes martensite and retained austenite by cooling to room temperature.
  • bainite area ratio is less than 65%, the C concentration in the untransformed austenite becomes small, so that a lot of martensite is generated by the subsequent cooling.
  • martensite ratio is increased, high strength is obtained, but notch sensitivity is remarkably increased, so that fatigue strength is reduced.
  • bainite is made 65% or more by area ratio.
  • Residual austenite is effective in improving ductility and toughness and reducing notch sensitivity by utilizing the TRIP (Transformation-induced plasticity) phenomenon.
  • the TRIP phenomenon is a phenomenon in which ductility and toughness of a material are remarkably improved by causing a processing-induced transformation accompanied by volume expansion by plastic deformation and generating processing-induced martensite.
  • Residual austenite causes a work-induced martensitic transformation at the stress concentration portion at the crack tip, and the stress concentration can be reduced by its volume expansion.
  • retained austenite undergoes work-induced martensitic transformation by shot peening, it is possible to form a compressive residual stress layer that is high in the surface and reaches deep inside by its volume expansion. For this reason, the retained austenite ratio is set to 4% or more, but if it is excessive, the material strength is remarkably lowered.
  • ⁇ Martensite balance (including 0%) An appropriate amount of martensite may be contained depending on the case where a desired tensile strength is ensured. In addition, the case where the sum of bainite and retained austenite is 100% and martensite is 0% is included.
  • Residual austenite has an effect of reducing notch sensitivity due to high ductility and toughness as a result of higher tensile strain at which processing-induced martensitic transformation starts as the C concentration increases.
  • the volume expansion due to work-induced martensitic transformation of retained austenite increases as the C concentration of retained austenite increases, and promotes relaxation of stress concentration at the crack tip and generation of compressive residual stress that is high and deep inside the surface. Therefore, it is more effective in improving fatigue resistance.
  • the average C concentration of retained austenite is required to be 0.65% or more. Residual austenite is remarkably stabilized when its C concentration becomes too high, and thus acts only as a soft phase, so the upper limit is 1.7%.
  • the compressive residual stress of the spring surface is given by setting and shot peening.
  • a compressive residual stress layer that is higher and deeper on the surface is formed by the processing-induced martensitic transformation of the retained austenite of the wire.
  • the compressive residual stress on the surface is set to 900 to 2000 MPa. If the surface compressive residual stress is less than 900 MPa, it is not possible to prevent crack growth of a microcrack existing on the spring surface, which is insufficient for suppressing fatigue fracture at the surface origin. On the other hand, if the maximum compressive residual stress on the surface is remarkably high, internal fracture tends to occur due to the tensile residual stress caused by the stress balance inside the strand, so 2000 MPa is set as the upper limit.
  • a range of about 200 ⁇ m to D / 4 from the surface is likely to be a starting point of fatigue failure.
  • the compressive residual stress at a depth of 0.3 mm from the surface is less than 200 MPa, it is insufficient to suppress fatigue fracture at the internal origin. For this reason, the compressive residual stress at a depth of 0.3 mm from the surface is set to 200 MPa or more.
  • the average Vickers hardness of the wire core is 550 HV or more in order to ensure the strength that can withstand the required load.
  • the hardness is excessively high, the notch sensitivity of the steel material itself increases, and the fatigue strength may decrease, so the Vickers hardness of the core is suppressed to 650 HV or less.
  • the material cost can be reduced and the manufacturing process can be simplified, and a spring having a high compressive residual stress layer with improved fatigue resistance can be obtained.
  • 1A to 1C show an example of the manufacturing process of the spring of the present invention.
  • C 0.5 to 0.7%
  • Si 1.0 to 2.0%
  • Mn 0.1 to 1.0%
  • Cr 0.1 to 1.0%
  • Cold coiling is performed in a spring shape by a coiling machine using an oil temper steel material having a composition of P: 0.035% or less, S: 0.035% or less, and the balance being iron and inevitable impurities (forming step).
  • the spring-shaped steel material is austenitized at a temperature of Ac3 point to (Ac3 point + 250 ° C.) and then cooled at a rate of 20 ° C./second or more, and (Ms point ⁇ 20 ° C.) to (Ms point + 60 ° C.). ) At a temperature of 400 seconds or more, and then cooled to room temperature at a cooling rate of 20 ° C./second or more (heat treatment step). Thereby, the structure
  • a shot peening process for projecting shots is performed.
  • the shot peening process is performed three times after the setting process.
  • a shot peening process may be performed before the setting process.
  • a round cut wire as a first step a round cut wire with a sphere equivalent diameter smaller than the first step as a second step, and a sphere equivalent diameter smaller than the second step as a third step
  • the residual stress generated by coiling is made substantially zero, a compressive residual stress layer that is higher and deeper on the surface of the strand can be formed by this shot peening.
  • the retained austenite of the wire surface layer is transformed into martensite by processing-induced transformation, so that deep compressive residual stress is formed, which suppresses the growth of fatigue cracks and further improves fatigue resistance. it can.
  • the compressive residual stress on the surface is impaired, but by applying shot peening after setting, the surface roughness can be improved while restoring the compressive residual stress on the wire surface, Fatigue fracture starting from the surface can be prevented, and fatigue resistance can be remarkably improved.
  • the spring of the present invention manufactured by the process as described above has a structure in which the bainite is 65% or more, the retained austenite is 4 to 13%, and the balance (including 0%) is martensite in an arbitrary cross section.
  • the average carbon concentration in the retained austenite is 0.65 to 1.7%
  • the surface has a compressive residual stress of 900 to 2000 MPa in an arbitrary cross section, and is 0.3 mm from the surface.
  • the compressive residual stress is 200 MPa or more
  • the average Vickers hardness of the core is 550 to 650 HV in an arbitrary cross section. Therefore, the spring of the present invention is excellent in fatigue resistance.
  • 1A to 1C show a manufacturing process of the spring of the present invention, and a shot peening process is performed after the setting process and before and after the setting process.
  • FIG. 1D shows a conventional manufacturing process, in which a setting process is performed after the shot peening process.
  • the first shot peening uses a round cut wire with a sphere equivalent diameter of 0.8 mm
  • the second shot peening uses a round cut wire with a sphere equivalent diameter of 0.45 mm
  • the third shot peening uses a sand grain with a sphere equivalent diameter of 0.1 mm.
  • a metal structure was performed as follows, after immersing a sample for several seconds in a 3% nital liquid. Because bainite is easily corroded by nital, it appears black or gray in optical micrographs. On the other hand, martensite and retained austenite appear white in the optical microscope because of their high corrosion resistance to nital. Utilizing this characteristic, the optical micrograph was subjected to image processing to determine the bainite (black and gray part) ratio and the total ratio of martensite and retained austenite (white part). The retained austenite ratio was determined using an X-ray diffraction method after buffing the sample.
  • the martensite ratio was determined by subtracting the retained austenite ratio determined by X-ray diffraction from the total ratio of martensite and retained austenite determined from the optical micrograph.
  • the lattice constant a (nm) obtained from each diffraction peak angle of (111), (200), (220) and (311) of austenite by X-ray diffraction is used. It calculated using the relationship of the following formula
  • equation (1). [Equation 1] a (nm) 0.3573 + 0.0033 ⁇ (mass% C) (1)
  • Samples 1 to 3 had good surface compressive residual stress, and the compressive residual stress at a position 0.3 mm from the surface was also a high value. This is because the compressive residual stress is temporarily lost because the surface of the element wire yields and deforms by setting, but the surface compressive residual stress can be recovered by performing shot peening after the setting step. On the other hand, No. which does not satisfy the conditions of the present invention. Samples 4 to 9 did not satisfy the predetermined compressive residual stress value for the following reason.

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Abstract

L'invention concerne un ressort présentant une couche à contrainte résiduelle de compression élevée dotée d'une résistance accrue à la fatigue, un processus de production à simplicité accrue, ainsi qu'un coût de matières réduit. L'invention concerne également un procédé de production de ce ressort, comprenant : une étape de formation permettant d'obtenir une forme de ressort dans un matériau d'acier contenant comme composants de 0,5 à 0,7% en masse de C, de 1 à 2% en masse de Si, de 0,1 à 1% en masse de Mn, de 0,1 à 1% en masse de Cr, pas plus de 0,035% en masse de P et pas plus de 0,035% en masse de S, le reste étant constitué de fer et d'impuretés inévitables ; une étape de traitement thermique pour obtenir une austénitisation à une température du point Ac3 de (point Ac3 + 250°C), puis un refroidissement à une vitesse d'au moins 20°C/seconde, un maintien isothermique pendant au moins 400 secondes à une température de (point Ms - 20°C) de (point Ms + 60°C), puis un refroidissement à température ambiante à une vitesse de refroidissement d'au moins 20°C/seconde ; une étape de durcissement destinée à conférer une déformation permanente ; et une étape de grenaillage destinée à projeter un tir.
PCT/JP2012/058876 2011-04-01 2012-04-02 Ressort et procédé de production associé WO2012133885A1 (fr)

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JP2011081966A JP2012214859A (ja) 2011-04-01 2011-04-01 ばねおよびその製造方法

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WO2018106606A1 (fr) * 2016-12-05 2018-06-14 Apros Therapeutics, Inc. Composés de pyrimidine contenant des groupes acides
EP4163406A1 (fr) * 2021-10-05 2023-04-12 Sintokogio, Ltd. Procédé de fabrication d'un élément métallique à contrainte résiduelle

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