EP2192201B1 - Gehärteter Federstahl, Federelement und Verfahren zur Herstellung eines Federelements - Google Patents

Gehärteter Federstahl, Federelement und Verfahren zur Herstellung eines Federelements Download PDF

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Publication number
EP2192201B1
EP2192201B1 EP09014562.4A EP09014562A EP2192201B1 EP 2192201 B1 EP2192201 B1 EP 2192201B1 EP 09014562 A EP09014562 A EP 09014562A EP 2192201 B1 EP2192201 B1 EP 2192201B1
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EP
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Prior art keywords
hardness
spring
spring steel
depth
softened
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EP09014562.4A
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German (de)
English (en)
French (fr)
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EP2192201A1 (de
Inventor
Jörg Neubrand
Maik Hartwig
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Muhr und Bender KG
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Muhr und Bender KG
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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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
    • 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
    • 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
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods

Definitions

  • the invention relates to a hardened spring steel, a spring element, and a method for producing a spring element.
  • the service life of spring elements is essentially influenced by the externally impressed stresses, the material, the applied heat treatment and possibly by a shot peening treatment.
  • the aim is to build the highest possible compressive residual stresses down to deep surface areas.
  • the residual stresses change their sign of life-improving pressure to life-deteriorating tensile residual stresses at a depth of about 200 microns to 400 microns below the surface. It forms due to the Hertzian pressure generated by shot peening an internal stress distribution, in which the maximum of the compressive residual stress is depending on the method used at a depth of about 50 microns to 150 microns below the surface of the spring steel.
  • the stresses acting in a spring are maximum at the surface and decrease towards the core.
  • material dwarfings - such as roughness, cracks, tinder, corrosion scars, shallow inclusions, etc. - result in notch stresses that can exceed the macroscopic stresses by a multiple.
  • the higher the hardness of the spring steel the greater the notch stresses are, which is tantamount to decreasing toughness of the spring steel. This removes the susceptibility to damage to, in particular due to stress corrosion cracking due to notch stresses.
  • a method of manufacturing a steel wire for a high strength cold formed coil spring is known. After hardening of the steel wire, it is subjected to heat treatment by means of inductive heating, so that the surface hardness is less than or equal to 550 HV to a predetermined depth and the tensile strength in a core region is greater than or equal to 200 kgf / mm 2 .
  • the spring wire is heated over the entire cross section. The hardness is based on the surface of the spring wire over the entire depth, that is, in the core area, below 590 HV.
  • the DE 198 52 734 A1 describes a spring with improved corrosion fatigue strength.
  • a steel with a certain composition is used for the production of spring steel, which is cured to a hardness of 50.5 to 55.0 HRC (hardness Rockwell C), wherein the curing followed by a shot peening treatment at moderate temperatures.
  • HRC hardness Rockwell C
  • the temperature is chosen such that a hardening waste in the edge area is avoided.
  • the DE 100 32 313 discloses a coil spring made of alloyed steel, wherein the coil spring is hardened and has a core hardness of about 610 HV 0.1 (hardness Vickers). To increase the wear resistance, a diffusion layer with a thickness of about 100 microns is provided, the hardness of which is more than 750 HV 0.1 at a depth of 10 microns.
  • the DE 41 38 991 discloses a method for producing different mechanical properties between the edge and core regions of a steel body.
  • the steel body is subjected to a work hardening treatment and then the edge and core portions are heated to different temperatures.
  • the DD 267 513 A1 discloses a high-strength steel for use in prestressed concrete construction, which has a higher strength in the core area than in the edge zone.
  • a spring and a method of manufacture is known.
  • the spring material is adjusted to a hardness of more than 500 HV and then heated by a heat treatment by means of high-frequency electrical energy of greater than 10 MHz to 500 to 700 ° C.
  • the hardness remains at over 500 HV.
  • From the JP 62 260020 A is also a spring or a process for their preparation is known in which the hardness is adjusted in a range of 10 microns, starting from the surface to a hardness of less than 450 HV.
  • the surface-hardened layer is softened by a heat treatment, which is carried out at 450 ° C to 750 ° C. This achieves a softened edge layer having a depth of up to about 0.1 mm, which has a hardness greater than 520 HV.
  • a high strength spring wire having a decarburized surface layer with a reduced hardness is known.
  • the decarburized layer extends to a maximum depth of 200 microns from the wire surface and has a hardness of 420 HV to 50 HV below the hardness inside the wire.
  • a spring steel and a method for producing a spring steel are known.
  • the spring steel is first hardened and then tempered.
  • Hardness and fatigue strength are reported for different spring samples for a scraped, non-scraped and a comparative sample. The fatigue strength is best with the scraped spring sample.
  • the hardness profile increases from outside to inside for all three spring steels to a depth of about 100 microns and then runs constant or decreasing. From a depth of about 100 micrometers, the hardness for all spring steels is over 600 HV.
  • the object of the present invention is to reduce the negative effects of possible critical notch stresses by material dances in an edge region of a spring steel or a spring element.
  • the invention is accomplished by a hardened spring steel made by inductive heating to austenitizing temperature, followed by quenching, and inductive heating to tempering temperature and an external one by inductive heating entognie edge layer having a thickness of at least 500 microns, within which the hardness decreases from the inside outwards, such that the hardness of the edge layer, starting from a surface of the spring steel to a depth of at least 500 microns increases with increasing depth, wherein the surface layer to a depth of at least 500 microns has a maximum hardness of 590 HV; and wherein the spring steel has an unconsolidated core region having a hardness of at least 600 HV beginning at a depth of at least 500 ⁇ m.
  • notch stresses depends on the reason of a surface crack, that is, on a crack tip, on the hardness or toughness of the material, this will slow down or even avoid extension of the crack.
  • the component mass of a spring element can be reduced and / or the life of the spring element can be increased.
  • a hardened spring steel is understood in this context, a spring steel, the mechanical resistance is increased by targeted change and transformation of its microstructure. This is preferably achieved by a heat treatment followed by rapid cooling.
  • a heat treatment should be such spring steels that are subjected to a further treatment after curing, for example, be tempered.
  • Such a heat treatment from hardening and subsequent tempering is also referred to as tempering.
  • a significant advantage of the invention is that can be deformed by the Randentfest Trent also components with higher output strength.
  • the risk of unwanted wire breaks after hardening or quenching is significantly reduced. This is achieved by increasing the ductility in the edge region. Namely, according to the invention, with the same integral tensile strength as compared with conventional components, the ductility increases, which can be up to 15% higher than with non-softened components.
  • Another advantage of the spring steel according to the invention with decreasing hardness from inside to outside is that the wire ductility is increased.
  • Spring steel refers to materials used to make technical springs.
  • a technical spring is a component that can absorb, store and then release the externally applied force.
  • all hardenable steels come into consideration as materials for spring steel.
  • the spring property is achieved with spring steel by the addition of different alloying elements.
  • the elements silicon, manganese, chromium, vanadium or molybdenum come into question.
  • Particularly suitable for the requirements of springs are silicon-chromium steels, silicon-chromium-vanadium steels and chromium-vanadium steels.
  • the spring steel is hardened or tempered in its entire cross section.
  • a through hardening or thorough tempering of the spring steel is softened by a heat treatment.
  • This can preferably be done by a relatively high-frequency inductive heating, which is to be understood as the use of frequencies above 50 kHz or 60 kHz.
  • the inductive heating can be carried out over a relatively short duration.
  • the edge layer Since it has been found that for the life of a spring element critical corrosion scars have a depth in the size range of 300-400 microns, the edge layer has a thickness of at least 500 .mu.m, in particular of at least 800 microns. This ensures that an increase in the toughness of the material and thus a reduction in the negative effects of the notch stress are achieved at the crack tip of a surface crack or at the bottom of a corrosion scar.
  • the surface layer can also be up to 1/4 of the radius of the spring element. In this case, the edge layer may even have a thickness of more than 800 microns and up to 2000 microns in special cases.
  • the edge layer preferably has a maximum hardness of 590 HV to a depth of 500 .mu.m to 800 .mu.m. It can be provided that the hardness of the edge layer starting from a surface of the spring steel with increasing depth increases. In general, the hardness of the spring steel over the depth depends on the integral tensile strength of the spring steel over its cross section. The higher the integral tensile strength, the greater the depth, up to which a maximum hardness of 590 HV can be present. Thus, with low integral tensile strength of the spring steel, the surface layer can even have a maximum hardness of 590 HV up to a depth of up to 1000 ⁇ m.
  • a hardness of at least 250 HV, preferably 450 HV, in particular of at least 500 HV or 560 HV is provided in the boundary layer from a depth of 50 microns.
  • a core region adjoining the surface layer begins at a depth of at least 500 ⁇ m, in particular of at least 800 ⁇ m.
  • the core area can even begin at a depth of 2000 microns.
  • the hardness of the core area is at least 600 HV.
  • the hardness of the core region can even exceed 730 HV, which can be achieved by a lower tempering temperature.
  • the hardness may be reduced or increased as a result of manufacturing-related microstructural changes, such as segregation.
  • the object is further achieved by a spring element, which is made of a spring steel, as described above.
  • the spring steel is in this case preferably a round material, for example a spring wire, an oval wire or a flat material, for example a spring band.
  • the spring element can be wound into a coil spring.
  • the spring steel may have a softened edge layer only on an inner side of the turns of the round material of the coil spring in order to reduce the effects of notch stresses. Viewed over the remaining circumference of the round material in cross-section, it can be provided that no softened edge layer is provided, ie that the core area extends to the surface.
  • the spring steel on an outer side of the turns of the Round material of the coil spring has a softened edge layer, whereby possible winding breaks in the shaping of the spring can be avoided.
  • the softened edge layer viewed in cross-section, extends over the entire circumference of the round material.
  • the object is achieved by a method for producing a spring steel, wherein the spring steel is first cured by inductive heating to Austenitmaschinestemperatur and subsequent quenching, wherein a core region is cured to a hardness of about 600 HV, then tempered by inductive heating and then a Edge layer of the spring steel over a thickness of at least 500 microns is softened by an inductive heat treatment, such that the hardness of the softened edge layer increases from a surface of the spring steel to a depth of at least 500 microns with increasing depth and maximum 590 HV.
  • the hardening or tempering of the spring steel means, preferably, that the entire cross section is first through hardened. However, the central region of the cross section does not necessarily have to be through hardened.
  • the structure of the spring steel is fine-needle martensitic. This martensitic structure is achieved by relatively rapid cooling after curing. Depending on the cooling rate after curing, a different microstructure of the spring steel can be produced. If the spring steel cooled more slowly, for example, a bainite microstructure can be generated. With even slower cooling, the retention of the ferrite / pearlite microstructure of the spring steel is conceivable.
  • the spring steel is hardened or tempered.
  • the spring steel is first heated to the austenitizing temperature, namely inductively heated, and then quenched.
  • the temperature here are preferably above the Ac 3 Point, especially at 800 or 900 to 1000 ° C.
  • the spring steel is tempered after hardening, to which the spring steel is inductively heated again.
  • the spring steel is preferably heated to a temperature of 400 ° C to 500 ° C or to 550 ° C. This is a tempered spring steel.
  • the spring steel is once again inductively heated for a short time in order to soften the surface layer.
  • the edge detackifying depending on the duration of the heating, preferably at a temperature between 500 ° C and 750 ° C, in particular between 570 ° C and 610 ° C.
  • the core area is set to a hardness of more than 600 HV, in special cases more than 730 HV.
  • the surface layer is softened over a thickness of at least 500 .mu.m, in particular of at least 800 .mu.m, wherein the edge layer is preferably softened to a maximum hardness of 590 HV. In special cases, depending on the integral tensile strength of the spring steel, the surface layer can even be softened over a thickness of more than 800 ⁇ m and up to 2000 ⁇ m.
  • the surface layer is preferably debonded from a depth of 50 microns to a hardness of not less than 250 HV, preferably not below 450 HV, in particular not below 500 HV or 560 HV.
  • a method for producing a spring element made of a spring steel wherein the spring steel is produced by one of the above-mentioned methods.
  • the spring steel is wound into a spring element in the form of a helical spring, wherein the boundary layer can be softened either before the winding of the spring steel or after the winding of the spring steel.
  • FIG. 1 shows a portion of a spring steel according to the invention in the form of a spring wire 1 with a circular cross-section.
  • the spring steel be designed with any cross-sections, for example, as a spring band.
  • the spring wire 1 extends along a longitudinal axis L.
  • the coordinates of the cross section are indicated by X (depth from the surface of) and Y (radius by the depth).
  • X depth from the surface of
  • Y radius by the depth
  • the spring wire 1 has an edge layer 2 and a core region 3, the edge layer 2 forming the surface 4 of the spring wire 1 on the outside.
  • the edge layer 2 and the core region 3 are not to be understood as separate elements, but merely serve to illustrate the different hardness properties.
  • the spring wire 1 is an integral element.
  • the spring wire 1 has a lower hardness in the region of the edge layer 2 than in the core region 3.
  • the softened edge layer 2 is arranged over the entire circumference about the longitudinal axis L viewed in cross section.
  • the softened edge layer 2 can also be provided only partially, so that it extends only partially over the circumference and / or extends only partially over the length.
  • the spring steel is made of a hardenable steel. Particularly suitable for the requirements of springs are silicon-chromium steels, silicon-chromium-vanadium steels and chromium-vanadium steels.
  • FIG. 2 schematically shows the curve 16 of the hardness curve over the entire cross section of the spring wire according to FIG. 1 along the axis X.
  • FIG. 3 shows in an enlarged view schematically the hardness curve in the region of the edge layer along the axis X. On the abscissa, the depth of the surface or the distance from the surface is removed. On the ordinate the hardness is removed.
  • the FIGS. 2 and 3 will be described together below.
  • the hardness of the spring wire increases substantially continuously until a maximum value is reached which is approximately constant in the core region of the spring wire.
  • the hardness may also be different, in particular lower, due to microstructural influences during production, for example due to segregations.
  • the increase in hardness, in each case from outside to inside, is present at all points of the surface of the wire.
  • a hardness of approx. 500 HV hardness Vickers
  • the hardness increases substantially continuously up to a value of approx. 580 HV.
  • This area represents the softened edge layer 2 whose hardness is lower than the hardness of the core area 3. From a depth of 0.6 mm, the hardness profile is constant until the opposite surface area is reached, where the hardness decreases towards the surface again.
  • the hardness should not be lower than a hardness lower limit of 450 HV.
  • the hardness should not exceed a hardness upper limit 18 of 590 HV.
  • the boundary layer 2 can also extend to a greater depth of up to 0.8 mm, in which case the core region can also have higher hardnesses of well over 600 HV.
  • the curve according to the FIGS. 2 and 3 is shown only schematically and represents the desired hardness profile. This is not achievable in reality in the straight line shape shown.
  • FIG. 4 shows measured values of the hardness curve in a region near the surface of a spring steel.
  • two curves are shown, on the one hand a first curve 5, which reproduces the hardness curve of the hardened or tempered spring steel without Entumbleen edge region.
  • a second curve 6 shows the hardness curve as it appears after the softening of the surface layer 2.
  • the edge layer of the spring steel is through a short-term heating softens, so that a hardness profile according to the curve 6 is achieved.
  • the edge layer 2 should have a minimum thickness starting from the surface of 0.3 mm, preferably 0.5 mm, and have a hardness of 450 to at most 590 HV.
  • the curve 6 increases continuously starting from the surface in the direction of the core region 3 and continues to approach the curve 5 of the hardness curve of the hardened or tempered spring steel and merges into it in the core region 3.
  • the core region can thus be defined as that region of the spring steel which is not softened.
  • the softened edge layer in the present example is about 0.6 mm thick and should be softened in this range to a hardness between 450 and 590 HV.
  • a transition region 19 which has also been softened, but has a hardness of more than 590 HV, wherein the hardness of the transition region 19 continues to increase up to the hardness of the core region.
  • a spring element in the form of a helical spring 7 is shown with a geometric spring center line M wherein a detail X is marked.
  • FIG. 6a and 6b show cross sections in the area of the detail X according to FIG. 5 by two embodiments of the spring wire from which the coil spring 7 is made.
  • FIG. 6a shows a core region 8 and an edge layer region 9, which extends only over part of the circumference, wherein the edge layer region 9 is provided on an outer side of the coil spring 9.
  • the softened first boundary layer region 9 is intended to prevent fractures during forming of the spring wire, ie during winding of the helical spring 7.
  • FIG. 6b shows a core region 8 and an edge layer region 10, which also extends over only a portion of the circumference, wherein the edge layer region 10 is provided on an inner side of the coil spring 7.
  • the softened edge layer region 10 is intended to locally reduce the negative effects of the notch stress.
  • the softened edge layer regions 9, 10 are shown sickle-shaped, they may also have other shapes or extend over a larger or smaller area of the circumference. Furthermore, the softened edge layer can extend over the entire length of the spring wire or only over part of the length of the spring wire.
  • FIG. 7 shows schematically the production of a spring steel in the form of a spring wire 1, wherein the softening takes place before the further processing of the spring wire, for example, to a helical spring.
  • the softening of an edge layer can take place even after the forming of the spring wire 1 into a helical spring.
  • the spring wire 1 is first passed through a first induction coil 11 and heated to Austenitmaschinestemperatur. Subsequently, the spring wire 1 is quenched, which takes place in a shower 12. Subsequently, the spring wire 1 is passed through a second induction coil 13 and heated to a tempering temperature.
  • the tempering temperature of the spring wire 1 is preferably 30 ° C lower than conventional inductive remuneration, in particular between 420 ° C and 490 ° C. In this case, the tempering temperature is dependent on the desired final strength of the spring wire 1, which should lie in a favorable manner between 1800 N / mm 2 and 2050 N / mm 2 .
  • the tempering temperature is lower and is preferably 380 ° C to 420 ° C.
  • the temperature of the spring wire is measured behind the second induction coil 13, preferably 50 mm to 90 mm, in particular 70 mm behind the induction coil 13. This staggered measurement, with distance to the induction coil 13, allows determining the core temperature of the spring wire first
  • a third induction coil 14 in which the spring wire 1 is briefly inductively heated to to soften the surface layer.
  • the edge hardening by heating is preferably carried out at a temperature between 500 ° C and 750 ° C, in particular between 570 ° C and 610 ° C. .. By choosing a suitable frequency in this case only the near-surface areas are heated.
  • the induction coils 11, 13, 14 are in FIG. 7 merely schematically illustrated and may of course be formed in various conventional forms for hardening spring wires.
  • a cooling unit can be integrated into the system in order to adjust specific material properties of the spring wire in a targeted manner.
  • the induction coil 14 for softening (directly before or after winding) may be designed in particular sickle-shaped, to allow the spring wire is only partially softened over its circumference.
  • the heating and softening temperatures may also differ from the temperatures mentioned.
  • FIG. 8 shows the relationship between the edge heating and the hardness of the spring wire 1, ie the edge or the core hardness, namely at different edge temperatures. It can be seen that the core strength is dependent on the desired integral tensile strength of the spring wire.
  • the curves of the hardness which are provided with the reference numerals 20, 21, 22, 23, 24, shown for different softening temperatures.
  • the softening is preferably carried out at a temperature between 500 ° C and 750 ° C, in particular between 570 ° C and 610 ° C.
  • the depth of the surface or the distance from the surface, in millimeters is removed.
  • the hardness, in hardness HV1 is removed. It can be seen that the hardness of the spring wire, starting from the surface (depth 0 mm) increases continuously until a maximum value is reached, which is approximately constant in the core region of the spring wire.
  • the hardness in the area of the surface and in the surface layer depends on the edge temperature. At a lower temperature, for example, 570 ° C, the hardness at the surface is particularly high, and here is about 570 HV and increases continuously to a depth of about 0.8 mm to a hardness of about 620 HV. This area of increasing hardness represents the softened edge layer 2 whose hardness is lower than the hardness of the core area 3. From a depth of 0.8 mm, the hardness profile is constant until the opposite surface area is reached where the hardness is towards the surface decreases again.
  • the hardness at the surface is slightly lower, here about 530 HV, and increases continuously to a greater depth of about 1.0 mm where it has a value of about 630 HV. That is, at higher heating temperature to achieve the Randentfestist the hardness in the surface layer decreases more and there is a softening into greater depth.
  • curve 25 shows the hardness curve for a heating at 610 ° C for edge hardening.
  • the hardness at the surface is only about 500 HV and increases continuously to a depth of about 1.25 mm.
  • the spring element has a hardness of about 650 HV.
  • FIGS. 9 and 10 show two examples of actual measured values of the hardness curve over the entire cross section of two inventive spring wires 1. It shows FIG. 9 the hardness curve for a spring wire with a higher integral tensile strength, amounting to 2086 N / mm 2 , while FIG. 10 the hardness curve for a spring wire with a lower integral tensile strength, in the amount of 2000 N / mm 2 shows. The diameter of the spring wire is 12.05 mm.
  • the two FIGS. 9 and 10 will be described together below.
  • the hardness curve in FIG. 9 is somewhat steeper in the peripheral areas and increases from the surface where there is a hardness of about 550 HV to a depth of about 1.0 mm to a hardness value of about 600 HV largely linear. Further inside, ie from a depth of about 1.0 mm to a depth of 2.0 mm, the hardness continues to increase, albeit not linearly but curvilinearly, up to a maximum value of about 630 HV. Between the depth of 2.0 mm to the core, which is at 6.0 mm, the hardness drops off again slightly and reaches a relative minimum of about 610 HV at about 4.0 mm. The maximum hardness of approximately 650 HV is in the core of the spring wire. This point is identified by the reference numeral 30.
  • the hardness curve which in FIG. 10 is shown is similar. Here, too, the hardness increases steeply in the marginal areas, in order to then assume a flatter slope further inside. At a depth of about 2.0 mm, the maximum hardness is about 610 HV. This point is indicated by the reference 31 '. Further inside, ie from a depth of about 2.0 mm to the core, ie to a depth of 6.0 mm, the hardness drops off again slightly and reaches a relative minimum of about 600 HV in the core 30 '.
  • the starting material defines the strength or hardness of the finished produced spring wire according to the invention.
  • FIG. 9 For example, where a starting material with a higher integral tensile strength of 2086 N / mm 2 was used, the hardness of the finished edge-strengthened spring wire with a maximum hardness of 650 HV is also higher.
  • the hardness of the finished edge-strengthened spring wire is also lower and is about 610 HV.
  • the spring steel according to the invention and the inventive method for producing such a spring steel offers the advantage that can be deformed by the Randentfest Trent also components with higher output strength. Overall, this leads to an increased strength or hardness of the component. This is especially true for spring elements, which are made of the spring steel according to the invention.
  • the peripheral strengthening of the spring wire increases the ductility in the edge region. In this way, the risk of unwanted wire breaks after curing or the remuneration is significantly reduced. In addition, the wire formability is improved.

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EP09014562.4A 2008-11-21 2009-11-23 Gehärteter Federstahl, Federelement und Verfahren zur Herstellung eines Federelements Active EP2192201B1 (de)

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DE102008058516 2008-11-21
DE102009011118A DE102009011118A1 (de) 2008-11-21 2009-03-03 Vergüteter Federstahl, Federelement und Verfahren zur Herstellung eines Federelements

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US10294540B2 (en) 2013-03-12 2019-05-21 Honda Motor Co., Ltd. Steel wire for spring and method for manufacturing same
CN106795576B (zh) * 2014-09-04 2018-11-09 蒂森克虏伯弹簧与稳定器有限责任公司 用于生产冷成型的钢弹簧的方法
DE102017107487A1 (de) 2017-04-07 2018-10-11 Schaeffler Technologies AG & Co. KG Verfahren zur Herstellung einer Torsionsstabfeder und Stabilisator für ein Fahrwerk eines Kraftfahrzeugs
JP2022097327A (ja) * 2020-12-19 2022-06-30 デルタ工業株式会社 トーションバー及びその製造方法
JP7203910B1 (ja) 2021-07-01 2023-01-13 日本発條株式会社 コイルばね、懸架装置およびコイルばねの製造方法
KR20230093723A (ko) 2021-12-20 2023-06-27 주식회사 포스코 내구성이 우수한 고탄소 강판 및 그 제조방법, 산업용 또는 자동차용 부품
DE102022002394A1 (de) 2022-07-03 2024-01-04 LSV Lech-Stahl Veredelung GmbH Verfahren zur Hersteliung eines Werkstücks aus Stahl und durch das Verfahren hergestelltes Werkstück
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