EP2966186B1 - Stärkeelement und herstellungsverfahren dafür - Google Patents

Stärkeelement und herstellungsverfahren dafür Download PDF

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EP2966186B1
EP2966186B1 EP14760929.1A EP14760929A EP2966186B1 EP 2966186 B1 EP2966186 B1 EP 2966186B1 EP 14760929 A EP14760929 A EP 14760929A EP 2966186 B1 EP2966186 B1 EP 2966186B1
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temperature
manufacturing
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French (fr)
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EP2966186A1 (de
EP2966186A4 (de
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Shimpei Kurokawa
Takeshi Suzuki
Kosuke Shibairi
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NHK Spring Co Ltd
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NHK Spring Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
    • 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
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • 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
    • 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
    • C21D2211/004—Dispersions; Precipitations

Definitions

  • the present invention relates to a strength member and to a manufacturing method therefor having superior settling resistance and yield strength.
  • JP 2012-111992 discloses a technique in which larger plastic strain than that of the tempered martensite structure is applied without decreasing the fatigue resistance by forming fine bainite having superior ductility as a main structure after coiling. In this technique, the settling resistance is improved by reducing dislocation density, which has a negative effect on settling resistance, and by effectively fixing the dislocation using strain aging.
  • the above technique also has an advantage in that manufacturing cost can be decreased, because inexpensive material can be used.
  • an object of the present invention is to provide a strength member and a manufacturing method therefor in which settling resistance and yield strength can be substantially improved without reducing cost advantages or adding substantial process changes.
  • the inventors have conducted various research in order to solve the above problems, and consequently, they have found that the martensite generated by water-cooling in the austempering treatment is decomposed into ferrite and cementite by tempering, the dislocation is decreased, and whereby the settling resistance is drastically improved. Additionally, in general, the structure is rapidly softened with the decrease of the dislocation in the martensite, and as a result, the fatigue strength is reduced. However, they have also found that the lowering of the fatigue strength due to the decrease of the hardness is not generated by using fine bainite as a main structure. Furthermore, since in the present invention the settling resistance is improved with increase of the yield strength, the present invention can be applied to screw members such as a bolt, tie rods, or the like, in which high yield strength is required.
  • the strength member according to the present invention was completed based on the above knowledge, and it comprises, by mass %, 0.5 to 0.7 % of C, 1.0 to 2.0 % of Si, 0.1 to 1.0 % of Mn, 0.1 to 1.0 % of Cr, 0.035 % or less of P, 0.035 % or less of S, and the balance of Fe and inevitable impurities, wherein an area ratio of bainite is 65 % or more, and an average dislocation density of a freely selected cross section is 2.0 ⁇ 10 16 m -2 or less.
  • the residual shearing strain is 6.55 x 10 -4 or less and an area ratio of retained austenite is 6.5 % or less and is given by claim 1.
  • the manufacturing method of the strength member according to the present invention given by claim 1 contains a forming process which forms a wire material in a product shape, a heat treatment process which austenizes at a temperature from an Ac3 point to (Ac3 point + 250 degrees C), cools at a cooling rate of 20 degrees C/second or more, maintains a temperature from (Ms point - 20 degrees C) to (Ms point + 60 degrees C) for 400 seconds or more, and cools to room temperature, and a tempering process in which the product after the heat treatment is maintained at a temperature from 350 to 450 degrees C for 25 to 60 minutes, wherein the wire material comprises, by mass %, 0.5 to 0.7 % of C, 1.0 to 2.0 % of Si, 0.1 to 1.0 % of Mn, 0.1 to 1.0 % of Cr, 0.035 % or less of P, 0.035 % or less of S, and the balance of Fe and inevitable impurities and is given in claim 2.
  • the Ac3 point is a boundary temperature in which the material shifts from two-phase area of ferrite and austenite to single-phase area of austenite during heating
  • the Ms point is a temperature at which martensite starts to be generated during cooling.
  • the present invention is not limited to a spring, and it can be applied to screw members such as a bolt or various strength members such as a tie rod which requires such strength.
  • settling resistance and yield strength can be substantially improved without reducing cost advantages or adding substantial process changes, by reducing an average dislocation density on a freely selected cross section.
  • C is an important element which ensures a desired strength, and it is necessary to contain 0.5 % or more in order to obtain such an effect. However, when C is excessively contained, it is difficult to obtain the desired strength since the content of retained austenite which is a soft phase is increased. Therefore, the C content is set to be 0.7 % or less.
  • Si is an element which contributes to solid solution strengthening, and it is necessary to contain 1.0 % or more in order to obtain a desired strength. However, when Si is excessively contained, the strength is reversely decreased since the content of soft retained austenite is increased. Therefore, the Si content is set to be 2.0 % or less.
  • Mn is a deoxidizing element added during refining and is also an element in which the strength can be easily improved by increasing hardenability of steel material, and it is necessary to contain 0.1 % or more in order to obtain a desired strength. In contrast, when Mn is excessively contained, workability is easily decreased by generating segregation. Therefore, the Mn content is set to be 1.0 % or less.
  • Cr is an element in which the strength can be easily improved by increasing hardenability of a steel material. In addition, it also has a function in which pearlite transformation is delayed, and it is necessary to contain 0.1 % or more, since a bainitic structure can be stably obtained (a pearlite structure is suppressed) in cooling after austenitizing heating. However, when Cr is excessively contained, iron carbide is easily produced. Therefore, Cr content is set to be 1.0 % or less.
  • P and S are elements in which intergranular fracture is promoted by grain boundary segregation.
  • content thereof be as low as possible; however, they are inevitable impurities, and it is necessary to incur additional smelting cost in order to reduce the contents. Therefore, the upper limit is set to be 0.035 %. It is preferable that the contents of P and S be 0.01 % or less.
  • Bainite 65 % or more
  • the bainite is generally a metallic structure in which austenitized steel material is isothermal-transformed at a temperature range from martensitic transformation start temperature to about 550 degrees C, and it is made of bainitic ferrite and iron carbide.
  • the strength can be increased by bainite structure, even if the hardness is decreased by reducing dislocation in martensite, since the bainitic ferrite in matrix has high dislocation density and the iron carbide has a precipitation strengthening effect.
  • the bainite structure has a structure in which iron carbide is finely deposited in fine bainitic ferrite matrix, lowering of the grain boundary strength is small, and lowering of toughness and ductility is small, even if the strength is high. Therefore, the dislocation density can be decreased without generating defects such as cracks which have a negative effect on fatigue resistance, even if large plastic strain is applied.
  • the bainite is an essential structure for obtaining high intensity and high ductility, it is desirable that area ratio thereof be higher, and it is necessary that it be 65 % or more in order to obtain high toughness and high ductility.
  • non-transformed austenite in isothermal holding changes to martensite or retained austenite by cooling to room temperature.
  • the area ratio of bainite of not more than 65 % means that isothermal holding time is too short, and the area ratio of martensite is increased by cooling, since the degree of concentration of C in non-transformed austenite in this condition is low. Therefore, when the area ratio of bainite is not more than 65 %, the strength is increased by increasing the area ratio of martensite; however, since notch sensitivity is remarkably increased, the large plastic strain cannot be applied, and the settling resistance is not improved.
  • an amount of the retained austenite is an index which relates to an amount of the residual shearing strain, and the settling resistance is decreased when the amount of the retained austenite is excessive. It is desirable that the area ratio of the retained austenite be set to be 6.5 % or less from this point of view.
  • Vickers hardness at the center of a freely selected cross section of a product be 450 HV or more in order to ensure strength that can withstand a load required of the product.
  • the hardness is excessively high, an amount of stretch is reduced and the notch sensitivity of steel material is increased, and large plastic strain cannot be applied. Therefore, it is desirable that the Vickers hardness be 650 HV or less.
  • Fig. 1A is a schematic view showing a manufacturing method of an embodiment of the present invention
  • Fig. 1B is a schematic view showing a conventional manufacturing method.
  • the steel material having the above chemical composition is subjected to, for example, a coiling process, and a seat surface grinding process in which both end surfaces of the spring are ground, as necessary, and it is austenitized at a temperature range from an Ac3 point to (Ac3 point + 250 degrees C).
  • a structure of the steel material before heating at an Ac3 point or more is not limited.
  • hot-forged bar steel material or wire-drawn bar steel material can be used. In the following, each process will be explained, and grounds of numerical limitation thereof will be described as necessary.
  • the coiling process is a process which cold forms in a desired coil shape.
  • a forming method may use a method using a spring forming machine (a coiling machine), a method using core metal, or the like.
  • optional springs such as a leaf spring, a torsion bar, a stabilizer, etc., can be applied in addition to the coil spring.
  • This process is carried out as necessary, and it is a process which grinds both end surfaces of the spring so as to form a perpendicular surface to an axial core of the spring.
  • the coiled spring is austenitized, is isothermal-held, and then, is cooled, and therefore, the heat treatment process is completed.
  • a structure of the steel material before austenizing is not limited.
  • hot-forged bar steel material or wire-drawn bar steel material can be used. It is necessary that an austenizing temperature be in a range from an Ac3 point to (Ac3 point + 250 degrees C). When the austenizing temperature is at an Ac3 point or less, a structure of the material is not changed to austenite. In contrast, when it exceeds (Ac3 point + 250 degrees C), there is a problem in that prior austenite grains are easily coarsened and the ductility is lowered.
  • the cooling rate is not more than 20 degrees C/second, pearlite is generated during cooling, and as a result, bainite having an area ratio of 65 % or more cannot be obtained.
  • the isothermal holding temperature be in a range from (Ms point - 20 degrees C) from (Ms point + 60 degrees C), and the temperature is a very important controlling element in a manufacturing method for realizing spring steel material and springs of the present invention.
  • the isothermal holding temperature is not more than (Ms point - 20 degrees C)
  • the isothermal holding temperature exceeds (Ms point + 60 degrees C)
  • the bainite is coarsened, the tensile strength is lowered, and the strength which withstands load as a spring cannot be obtained.
  • fine bainite can be deposited by isothermal holding at a temperature close to the Ms point as described above. By depositing the fine bainite, fine spaces are retained in the austenite, and fine retained austenite grains are formed.
  • the bainite is deposited in the austenite by isothermal-holding. It is necessary that the isothermal holding time be 400 seconds or more, and this time is also a very important controlling element in the manufacturing method of the present invention.
  • the isothermal holding time is not more than 400 seconds, the bainitic transformation is not sufficiently progressed, and as a result, the area ratio of bainite is small and is not more than 65 %.
  • an amount of generated bainite is saturated, even if the isothermal holding time is excessively long, and as a result, production cost is increased. Therefore, it is desirable that the isothermal holding time be set to be 3 hours or less.
  • the tempering process which retains the spring at 350 to 450 degrees C is carried out after the heat treatment process.
  • the tempering temperature is not more than 350 degrees C, the martensite is not sufficiently decomposed, and the dislocation is insufficiently decreased.
  • the tempering temperature exceeds 450 degrees C, the inner hardness of the spring is remarkably decreased, and the strength and fatigue strength are reduced.
  • the tempering temperature be 400 degrees C or less in order to prevent the inner hardness of the spring from extremely decreasing.
  • the tempering time be 25 to 60 minutes. When the tempering time is not more than 25 minutes, the tempering is insufficient, and in contrast, when the tempering time exceeds 60 minutes, the tempering is uneconomical.
  • Shot peening is a method in which compressive residual stress is applied to a surface of a spring by striking with shot made of metal, sand, etc., and whereby the fatigue resistance of the spring is remarkably improved.
  • higher and deeper compressive residual stress is formed by strain induced martensitic transformation of retained austenite, in addition to the compressive residual stress obtained by usual shot peening.
  • cut wire, steel balls, high hardness particles made of FeCrB based material, etc., and the like can be used.
  • the compressive residual stress can be adjusted by efficacy, average sphere equivalent diameter, shooting rate, shooting time, and multistep shooting system of the shot.
  • the setting is optionally carried out by applying the plastic strain in order to remarkably improve elastic limit and reduce a settling amount (permanent deforming amount) in using.
  • the settling resistance can be further improved by carrying out the setting (hot setting) at 200 to 300 degrees C.
  • the retained austenite is strain-induced-transformed by setting, and it is expected to form martensite having higher strength. Therefore, the fatigue resistance can be further improved by applying high compressive residual stress due to volume expansion with the transformation.
  • a Si-Cr steel oil tempered wire (diameter: 4.1 mm) made of representative chemical composition described in Table 1 was cold-coiled in a fixed shape by a coiling machine, and then, it was subjected to a heat treatment (an austemper treatment).
  • a heat treatment an austemper treatment
  • a spring was austenitized by retaining at 830 degrees C in a heating furnace for 12 minutes and was water-cooled, and then, it was retained in a salt bath maintained at 300 degrees C for 40 minutes and was cooled.
  • the spring was subjected to tempering at a temperature shown in Table 2. The tempering was carried out for 60 minutes. In addition, in a shot-peening, steel shot having a sphere-equivalent diameter of 0.1 to 1.0 mm were used. Furthermore, the spring was heated at 200 to 300 degrees C, and was subjected to setting. With respect to the obtained spring, the following characteristics were researched in manners described below. Table 2 No.
  • the phases were distinguished in the following manner using structures in samples soaked in 3% nital solution for several seconds.
  • bainite is seen as black or gray in an optical microscope photograph since it is easily corroded by the nital solution, and in contrast, retained austenite is seen as white in an optical microscope photograph since it has high corrosion resistance to the nital solution.
  • total area ratio of the bainite (black and gray portions) and the retained austenite (white portion) was calculated by image processing of the optical microscope photograph.
  • the area ratio of the retained austenite of buffing finished samples was obtained using an X-ray diffraction method.
  • Table 2 residual structure of the bainite and the retained austenite is martensite in Nos. 1 and 2, and it is ferrite and cementite in Nos. 3 to 7.
  • the Vickers hardness was measured at 5 points at the center portion of a cross section of the samples, and an average value thereof was calculated.
  • the average dislocation density ⁇ was calculated by the following Equation 1 using strain ⁇ referring to document (" Evaluation Method of dislocation density using X-ray diffraction" in Material and Process: Iron and Steel Inst. of Japan lecture proceedings 17 (3), pages 396-399 ).
  • ⁇ 14.4 ⁇ 2 / b 2
  • Diffraction peaks of (110), (211) and (220) of ferrite were measured at the center portion of a cross section of the samples, by X-ray diffraction equipment (trade name: D8 DISCOVER produced by Bruker Corporation) using 0.3 mm collimeter, and then, using half width ⁇ of each peak, ⁇ cos ⁇ / ⁇ and sin ⁇ / ⁇ of each diffraction peak was plotted on a vertical axis and a horizontal axis of a graph, according to the following Equation 2, and inclination 2 ⁇ of an approximate curve thereof was obtained, and therefore, the strain ⁇ was calculated.
  • ⁇ is a half value of X-ray diffraction peak position 2 ⁇
  • ⁇ is a wavelength of K ⁇ 1 wave of the tubular bulb which is used as an X-ray emission source
  • D is a size of crystallite.
  • the residual shearing strain is an index which shows settling resistance of a spring. The lower the residual shearing strain, the better the settling resistance.
  • a settling test of the spring the sample was compressed and fixed by adding load so that the maximum shear stress was 1,050 MPa, and it was soaked in silicone oil at 165 degrees C. The sample was taken out from the silicone oil after soaking for 24 hours, and the load was released after cooling to room temperature. The load when the spring was compressed to a given height was measured before and after the above settling test, the load reduction amount ⁇ P was substituted to the following Equation 3, and therefore, the settling amount was obtained.
  • ⁇ 8 D / ⁇ d 3 G ⁇ ⁇ P
  • D is an average coil diameter
  • d is a wire diameter
  • a Si-Cr steel hard-drawn wire rod (diameter: 6.0 mm), made of a representative chemical composition in Table 1, was cut off to a predetermined size, and it was subjected to head forging and thread rolling to form a bolt, and it was subjected to heat treatment (austempering treatment).
  • the bolt was austenitized by retaining in a heating furnace at 830 degrees C for 12 minutes and was water-cooled, and then, it was retained in a salt bath maintained at 300 degrees C for 40 minutes, and was cooled.
  • the present invention can be applied to springs such as a coiled spring, a leaf spring, a torsion bar, and a stabilizer; screw members such as a bolt; or strength members such as a tie rod in which strength is required.
  • springs such as a coiled spring, a leaf spring, a torsion bar, and a stabilizer
  • screw members such as a bolt
  • strength members such as a tie rod in which strength is required.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
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Claims (5)

  1. Festigkeitsglied aufweisend in Gewichts-%, 0,5 bis 0,7 % an C, 1,0 bis 2,0 % an Si, 0,1 bis 1,0 % an Mn, 0,1 bis 1,0 % an Cr, 0,035 % oder weniger an P, 0,035 % oder weniger an S, und den Rest an Fe und unvermeidbaren Verunreinigungen,
    wobei ein Flächenverhältnis von Bainit 65% oder mehr ist, und eine durchschnittliche Versetzungsdichte eines frei gewählten Querschnitts 2,0 x 1016 m-2 oder weniger ist,
    eine Restschubspannung 6,7 x 10-4 oder weniger ist, und
    ein Flächenverhältnis von Restaustenit 6,5% oder weniger ist,
    wobei die Vickershärte im Zentrum eines frei gewählten Querschnitts des Produkts 450 bis 650 HV ist.
  2. Herstellungsverfahren für ein Festigkeitsglied nach Anspruch 1, aufweisend:
    einen Formprozess, der Drahtmaterial in eine Produktform formt,
    einen Wärmebehandlungsprozess, der bei einer Temperatur von einem Ac3 Punkt bis (Ac3 Punkt + 250 °C) austenitisiert, mit einer Abkühlrate von 20 °C/Sekunde oder mehr kühlt, bei einer Temperatur von (Ms Punkt - 20°C) bis (Ms Punkt + 60°C) für 400 Sekunden oder mehr hält, und auf Raumtemperatur abkühlt, und
    einen Temperprozess, in dem das Produkt nach der Wärmebehandlung für 25 bis 60 Minuten bei einer Temperatur von 350 bis 450 °C gehalten wird,
    wobei das Drahtmaterial in Gewichts-% aufweist, 0,5 bis 0,7 % an C, 1,0 bis 2,0 % an Si, 0,1 bis 1,0 % an Mn, 0,1 bis 1,0 % an Cr, 0,035 % oder weniger an P, 0,035 % oder weniger an S, und den Rest an Fe und unvermeidbaren Verunreinigungen.
  3. Herstellungsverfahren für ein Festigkeitsglied nach Anspruch 2, ferner aufweisend einen Kugelstrahlprozess, in dem eine Kugel auf ein Produkt aufprallt, nach dem Temperprozess.
  4. Herstellungsverfahren für ein Festigkeitsglied nach Anspruch 2 oder 3, wobei eine Abkühlrate beim Kühlen auf Raumtemperatur 20 °C/Sekunde oder mehr ist.
  5. Herstellungsverfahren für ein Festigkeitsglied nach Anspruch 3, ferner aufweisend einen Setzprozess, der eine permanente Verformung auf das Produkt aufbringt, nach dem Kugelstrahlprozess.
EP14760929.1A 2013-03-08 2014-03-07 Stärkeelement und herstellungsverfahren dafür Active EP2966186B1 (de)

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JP2013047106 2013-03-08
PCT/JP2014/056057 WO2014136966A1 (ja) 2013-03-08 2014-03-07 強度部材およびその製造方法

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EP2966186A1 EP2966186A1 (de) 2016-01-13
EP2966186A4 EP2966186A4 (de) 2016-11-23
EP2966186B1 true EP2966186B1 (de) 2019-10-16

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EP (1) EP2966186B1 (de)
JP (1) JP6284279B2 (de)
CN (1) CN105008572A (de)
ES (1) ES2765274T3 (de)
WO (1) WO2014136966A1 (de)

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DE102015217399A1 (de) * 2015-09-11 2017-03-16 Thyssenkrupp Ag Rohrfeder für Kraftfahrzeuge und ein Verfahren zum Herstellen einer Rohrfeder
DE102015217401B4 (de) * 2015-09-11 2018-04-05 Thyssenkrupp Ag Rohrfeder für Kraftfahrzeuge und ein Verfahren zum Herstellen einer Rohrfeder
WO2018099819A1 (en) * 2016-11-29 2018-06-07 Tata Steel Ijmuiden B.V. Method for manufacturing a hot-formed article, and obtained article
CN108179355A (zh) * 2018-01-31 2018-06-19 中钢集团郑州金属制品研究院有限公司 一种高强度高韧性弹簧钢丝及其制备工艺
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WO2023120475A1 (ja) * 2021-12-21 2023-06-29 日本発條株式会社 圧縮コイルばねおよびその製造方法
WO2023120491A1 (ja) * 2021-12-21 2023-06-29 日本発條株式会社 圧縮コイルばねおよびその製造方法
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EP2966186A1 (de) 2016-01-13
WO2014136966A1 (ja) 2014-09-12
EP2966186A4 (de) 2016-11-23
JP6284279B2 (ja) 2018-02-28
ES2765274T3 (es) 2020-06-08
CN105008572A (zh) 2015-10-28

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