ES2963989T3 - Spring wire, clamp formed therefrom and method for producing such a spring wire - Google Patents

Abstract

The invention provides a spring wire that can be easily cold formed even with diameters of at least 9 mm, but which has improved mechanical properties. For this purpose, a spring wire according to the invention is manufactured from a steel which, in % by weight, C: 0.35 - 0.42%, Si: 1.5 - 1.8%, Mn: 0.5 - 0.8%, Cr: 0.05 - 0.25%. , Nb: 0.020 - 0.10%, V: 0.020 - 0.10%, N: 0.0040 - 0.0120%, Al: <= 0.03%, and the rest is made up of iron and inevitable impurities, the content of the sum of impurities being limited to a maximum of 0.2% and the impurities including up to 0.025% of P and up to 0.025% of S. The spring wire according to the invention is particularly suitable for producing a tension clamp with properties optimized usage. The invention also discloses a method that allows the practical production of spring wires according to the invention. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Spring wire, clamp formed therefrom and method for producing such a spring wire

The invention relates to a spring wire, which has been produced from a spring steel with a carbon content of 0.35-0.42% by weight.

Furthermore, the invention relates to a clamp for holding under a rail for rail vehicles at a rail fixing point, which has been formed from such a spring wire, and to a method for the production of a spring wire of the type in question in this case.

At a "rail fixing point" the rail to be fixed in each case is fixed to the substrate, which carries the track to which the rail belongs. The substrate can be formed in this regard by a conventional sleeper, which is made of wood or by sleepers or plates that have been formed from a concrete material or a plastic material. The rail fixing point typically comprises at least one guide plate, which is in lateral contact with the rail and in use deflects the transverse forces acting on the rail on the substrate, and a clamping clip, which is braced against the rail. substratum. The clamping clamp exerts with the end of at least one spring arm on the base of the rail an elastic spring suppression force, by means of which the rail is held pressed on the substrate. The suppression forces can be applied particularly effectively by W-shaped or W-shaped clamping clips, which act with the free ends of their two spring arms on the rail base. Examples of clamping clips formed in this way are the products explained at URL https://www.vossloh.com/de/produkte-undloesungen/produktfinderl (location date August 12, 2019).

The spring wires, which are required for the generation of clamping clips, normally have circular diameters of 9 -15 mm. In this regard, in practical use, the individual sections of a clamp are loaded predominantly in bending or torsion, where to the dominant load in each case more or less strong proportions of the other form of loading can be added in each case. case.

The usual production route for its production includes the work steps "casting a steel melt to give casting blocks", "fully heating the casting blocks" and "hot rolling the casting blocks to give a spring wire ", "cooling the hot-rolled spring wire" and "depositing or winding the spring wire to give a coil", where hot rolling is usually carried out in several stages, comprising pre-rolling, intermediate rolling and rolling complete of the roughing to give the spring wire. The work steps to be followed in this regard and the influencing factors to be taken into account are known to the skilled person (see, for example, Stahl Fibel, 2015, Verlag Stahleisen GmbH, Düsseldorf, ISBN 978-3-514- 00815-1).

The clamping clips are cold formed from the spring wires generated in this way. For this, rods are cut from the spring wires, which are then usually bent in several steps to form the clamping clip. In this way, it is possible to generate clamping clips with a more complex configuration. The clamping clips obtained are finally subjected to heat treatment, in which they are heated to a temperature above Ac3 and then suddenly cooled, to optimize their mechanical properties through curing. In this regard, the objective is the setting of high tensile strengths Rm and high elastic limits Rp0.2. In this regard, the objective is a ratio Rm/Rp0.2 of “ 1, to be able to apply high elastic suppression forces with the clamping forceps on the one hand and to lengthen, on the other hand, the elastic formability range of the clamp. clamping clamp and accompanying this its limit of resistance to fatigue due to vibrations. Normally, the tensile strengths Rm and the elastic limits Rp0.2 in the case of clamps of the type in question in this case are in the range of 1200 - 1400 MPa.

Limits have been set to an increase in strength by, for example, raising the carbon content, in this case by the requirement that the spring wire must still be used in a cold-formed manner. A practically proven steel for the production of spring wires for clamping pliers, standardized in accordance with DIN EN 10089:2002 under the designation "38Si7" and registered under material number 1.5023 in the StahlEisen list is constituted therefore, in % by weight, for 0.35 - 0.42% of C, 1.50 -1.80% of Si, 0.50 - 0.80% of Mn and as a remainder for iron and unavoidable impurities, where unavoidable impurities include up to 0.025% P and up to 0.025% S.

In addition to the alloying measures, the mechanical properties of a spring wire intended for the production of spring elements can also be improved by so-called "thermomechanical rolling". In the case of a variant of such a thermomechanical rolling, which relates in particular to spring wire, which is intended for the production of springs loaded by bending, the spring wire is hot rolled in a temperature range in the that its structure has not yet been completely recrystallized, which however is above the Ar3 temperature of steel. In this way, spring wires with a particularly fine structure can be generated, which contributes to high strength and optimized elastic behavior of the clamping clip (DE 19546204 C1). In the case of another variant of a thermomechanical forming, which refers in particular to the spring wire treatment, which is intended for the production of torsionally loaded springs, the starting material in the form of a rod is heated with a heating rate of at least 50 K/s to a temperature above the recrystallization temperature and is then formed to a temperature at which dynamic and/or static recrystallization of the austenite results. The austenite recrystallized in this way from the forming product is quenched and annealed (DE 19839383 A1).

In addition to the state of the art explained above, the spring steel described in document CN 105 112774 A can also be mentioned, which can be hardened by cooling with air and with a comparatively low carbon content and microalloy elements must have high formability. . For this purpose, this known spring steel consists, in % by weight, of 0.15 - 0.50% C, 0.30 -2.00% Si, 0.60 - 2.50% of Mn, up to 0.020% of S, up to 0.025% of P, 0.0005 - 0.0035% of B and the remainder by Fe. After the steel thus composed has been heated to 900 - 1050 °C and has been maintained at this temperature, a structure is obtained by controlled cooling, the main constituent parts of which are bainite and martensite and which may additionally present smaller proportions of residual austenite. The properties of the steel can be further improved by low-temperature annealing. The steel thus treated must have a tensile strength Rm of at least 1350 MPa, a yield strength Rp0.2 of at least 1050 MPa and an elongation A of at least 10%.

Starting from the state of the art explained above, the objective has been to create a spring wire that can be cold-formed, also with diameters of at least 9 mm, but which has improved mechanical properties in this regard.

A spring wire that solves this objective has, according to the invention, at least the characteristics indicated in claim 1.

Furthermore, a clamping clip with optimized properties and a method that would allow the practical generation of spring wires according to the invention had to be indicated.

A clamping clip for holding under rails for vehicles on rails at a rail fixing point, which solves this object, has been formed from a spring wire provided in accordance with the invention.

A procedure, which solves the aforementioned objective, comprises according to the invention at least the work steps and characteristics indicated in claim 14. In this regard it is understood in itself that in carrying out the procedure according to the invention, The expert performs not only the procedural steps mentioned in the claims and explained in this case in detail, but also performs all other steps and activities that are regularly carried out in the practical implementation of procedures of this type in the state of the art. , when there is a need for it.

Advantageous embodiments of the invention are indicated in the dependent claims and are explained in detail below as the general idea of the invention.

In this text, unless expressly indicated otherwise, indications have been made regarding the contents of alloy constituent parts always in % by weight.

A spring wire according to the invention has been produced

constituted, in % by weight, by

C: 0.35 - 0.42%,

Yes: 1.5 - 1.8%,

Mn: 0.5 - 0.8%,

Cr: 0.05 - 0.25%,

Nb: 0.020 - 0.10%,

V: 0.020 - 0.10%,

N: 0.0040 -0.0120%,

Al: <0.03%,

and as a remainder by iron and unavoidable impurities, where the content of the sum of the impurities is limited to a maximum of 0.2% and the impurities belong up to 0.025% of P and up to 0.025% of S.

The alloy concept provided for the spring wire according to the invention is based on the fact that the tensile strength Rm and the yield strength Rp0.2 are raised by adding additional alloying elements. This makes it possible to maintain the carbon content and accompanying cold formability of the spring wire at an optimally low level for practical processing, yet at the same time raise the resistance Rm and the elastic limit Rp0.2 clearly compared to the state of the art. In particular, the individual alloy constituent parts and their contents in the alloy of a spring wire according to the invention have been determined as follows:

Carbon ("C") is present in the spring steel of a spring wire according to the invention in contents of 0.35 - 0.42% by weight, to ensure good formability, high toughness, good corrosion stability and low sensitivity to hydrogen- or stress-induced cracking. In this regard, C contents of at most 0.40% by weight, in particular less than 0.40% by weight, have proven to be particularly successful in terms of optimized ductility and accompanying optimized formability at room temperature.

Silicon ("Si") is present in the steel of a spring wire according to the invention in contents of 1.5 - 1.8% by weight, in particular 1.50 - 1.80% by weight, to ensure high strength through mixed crystal solidification. Furthermore, the high Si content ensures good stability ("relaxation stability") against a decrease in the resistance values of the spring wire during the heat treatment that the clamping clips formed from of the spring wire according to the invention after cold forming. For this, Si contents of at least 1.5% by weight are necessary. However, too high Si contents would reduce toughness, increase the risk of decarburization during heat treatment and would also contribute to the formation of coarse grain. Therefore the Si content according to the invention remains limited to 1.8% by weight.

Manganese ("Mn") is present in the steel of a spring wire according to the invention in contents of 0.5 - 0.8% by weight, to ensure sufficient hardenability of the spring steel. Furthermore, Mn binds to sulfur, which is generally unavoidable due to production, to give MnS and thus prevents its harmful action. This requires at least 0.5% by weight, in particular at least 0.50% by weight, of Mn in the steel, where an optimized action with contents of at least 0.6% in weight, in particular at least 0.60% by weight or at least 0.7% by weight. However, too high Mn contents would worsen the transition temperature from brittle to ductile (Ductile-Brittle-Temperature "DBTT"), therefore the Mn content is limited to a maximum of 0.8% by weight, in particular the 0.80% by weight.

Chromium ("Cr") is present in the spring steel of a spring wire according to the invention in contents of 0.05 - 0.25%, to further improve the hardenability of the steel. In this regard, the presence of Cr in the steel according to the invention guarantees that the structure of a clamping clip formed from a spring wire according to the invention is constituted after hardening to more than 95% in surface by martensite. By having a C content of at least 0.05% by weight, the carbon activity and the risk of marginal layer decarburization during heat treatment can also be reduced. The positive effects of Cr in the spring steel of a spring wire according to the invention can be exploited in this regard especially since a Cr content of at least 0.1% by weight is provided, in particular at least 0.10% by weight or in particular at least 0.18% by weight. In the case of Cr contents above 0.25% by weight, on the other hand, there is a risk that the toughness and relaxation stability of the spring steel would be affected.

Aluminum ("Al") is not required in the steel according to the invention for deoxidation during the generation of the steel, however it can be added to the spring steel optionally in contents of up to 0.03% by weight to promote the manifestation of a fine-grained structure. Higher Al contents would, however, impair, through excessive formation of Al oxides or nitrides, the purity of the steel of a steel according to the invention and accompanying this its toughness.

Niobium ("Nb") is especially important for the invention and is present in the spring steel of a spring wire according to the invention in contents of 0.02 - 0.1% by weight. The Nb reinforces the recrystallization during a thermomechanical rolling carried out in the temperature range of recrystallization stop temperature - Ar3 temperature of the spring steel, by which a particularly fine-grained structure of the spring wire according to the invention is obtained. . At the same time, the grain growth is limited by the presence of Nb, when the spring wire according to the invention is heated during heat treatment of the clamp formed therefrom to the austenitizing temperature and there it keeps. As a result, a clear improvement in strength is achieved by the addition of Nb according to the invention and the resulting manifestation of a particularly fine-grained structure, which is also preserved through the heat treatment that ultimately runs through a clamp. fastening. In order to be able to use the positive action of Nb especially safely, the Nb content of the spring steel of a spring wire according to the invention can be at least 0.0250% by weight, at least 0. 0280% by weight or at least 0.030% by weight. Nb can be used particularly effectively in this regard with contents of up to 0.070% by weight, in particular up to 0.050% by weight.

Vanadium ("V") is present in the spring steel of a spring wire according to the invention in contents of 0.020 - 0.10% by weight. V forms with carbon and nitrogen carbides and nitrides, which are usually found as precipitates of fine, large carbonitrides, for example 8 - 12 nm, in particular about 10 nm, and by precipitation hardening essentially contribute to the increase in strength of a spring wire according to the invention. At the same time, the V thus contributes to the relaxation stability of the spring steel, of which a spring wire according to the invention is constituted. In order to be able to use the positive action of the V especially safely, the V content of the spring steel of a spring wire according to the invention can be at least 0.0250% by weight, at least 0. 0280% by weight or at least 0.030% by weight. V can be used particularly effectively in this regard with contents of up to 0.070% by weight, in particular up to 0.060% by weight.

The combined presence according to the invention of Nb and V results in high tensile strengths Rm and usually approximately equally high yield strengths Rp0.2, so that in the case of a clamp produced from the wire of spring according to the invention the ratio Rm/Rp0.2 is regularly in the optimal range for its useful life and elastic behavior of 1 -1.2.

Nitrogen ("N") is provided in the spring steel of a spring wire according to the invention in contents of 0.0040 - 0.0120% by weight (40 - 120 ppm), to allow the formation of nitrides of vanadium or vanadium carbonitrides. However, too high N contents would favor aging due to deformation of the spring wire according to the invention, which would be diametrically opposed to the toughness of the spring wire according to the invention and to the limit of resistance to vibration fatigue required. by a clamping clamp. Negative effects of the presence of N in the spring steel of a spring wire according to the invention can be particularly reliably excluded because the N content is limited to at most 0.0100% by weight. (100 ppm).

A spring wire consisting of a spring steel composed in accordance with the invention achieves in the hot-rolled state a breaking stress Z determined in the tensile test in accordance with DIN EN ISO 6892-1. at least 55% and is thus generally higher than the breaking stress that can be determined with spring wires that are made of conventionally alloyed 38Si7 steel.

At the same time, in the hot rolled state, it has a fine grain size of its structure, determined in accordance with ASTM E112, of at least ASTM 10. This fineness of the structure largely remains through the cold forming of the spring wire. to give a clamp and subsequent heat treatment of the clamp. Thus, the clamping clips according to the invention, manufactured for mounting on a rail fixing point, regularly have a fineness of their structure, which, as determined by the ASTM E112 standard, corresponds to at least ASTM 8. This corresponds to an improvement of the fine granulation in at least one of the granulation classes indicated in ASTM E112 with respect to a clamping clip, which has been arched from a spring wire, which is constituted by conventional 38Si7 steel .

The method according to the invention for the production of a spring wire provided according to the invention comprises the following working steps:

a) melt a steel, which is made up, in % by weight, of C: 0.35 - 0.42%, Si: 1.5 -1.8%, Mn: 0.50 - 0.80%, Cr : 0.05 - 0.25%, Nb: 0.020 - 0.10%, V: 0.020 - 0.10%, N: 0.0040 - 0.0120%, AI: < 0.03% and as remainder iron and unavoidable impurities, where the content of the sum of the impurities is limited to a maximum of 0.2% and the impurities include up to 0.025% P and up to 0.025% S;

b) strain the steel to give a previous product;

c) hot rolling the previous product to give a hot rolled spring wire with a final diameter of 9 -15 mm, wherein the hot rolling is carried out in at least two partial stages, wherein the spring wire is rolled hot rolling completely in the last partial stage of hot rolling thermomechanically at a temperature that is below the recrystallization arrest temperature of the spring wire steel and above the Ar3 temperature of the spring wire steel ;

d) cooling the hot rolled spring wire completely thermomechanically with a cooling rate of 1 - 5 °C/s to a winding temperature of 550 - 650 °C;

e) depositing or winding the spring wire cooled to the winding temperature to give a coil;

f) cool the spring wire in the coil to room temperature.

According to the invention, the spring wire is therefore subjected during hot rolling to a thermomechanical rolling step, in which it is rolled at temperatures that are below the recrystallization stop temperature and therefore above the Ar3 temperature of the steel. The "recrystallization arrest temperature" is here designated the temperature to which the spring wire has cooled as long as no recrystallization of its previously austenitic structure takes place. By thermomechanical rolling carried out in the predetermined temperature range according to the invention in combination with the alloy selected according to the invention, in particular as a consequence of the simultaneous presence of Nb and V, the fine granulation structure is obtained, which characterizes a spring wire according to the invention in the hot rolled state.

At the same time, by cooling the hot-rolled spring wire with the predetermined cooling rates according to the invention and by maintaining the prescribed winding temperatures according to the invention of 550 - 650 ° C it is ensured that as consequence of precipitation hardening a maximum hardness of the spring wire according to the invention.

Basically it would be conceivable to carry out the partial hot rolling step "thermomechanical rolling" in a separate work cycle, which is carried out after the actual hot rolling of the spring wire. For this purpose, the provided hot-rolled spring wire is first heated to the austenitizing temperature, then cooled to a temperature that is below the recrystallization stopping temperature, but above the recrystallization temperature. Ar3 of spring steel and at this temperature it is hot rolled with a sufficient degree of deformation. Following this, the cooling and deposition or winding of the spring wire is carried out as indicated in working steps d) and e) of the method according to the invention.

A variant of the process according to the invention, optimized from a technological and economic point of view, however, provides that all partial steps of hot rolling (working step c)) are completed in the continuous cycle, which is therefore a hot rolled spring wire completely also thermomechanically, when the spring wire leaves the hot rolling segments used in each case.

The invention is explained in greater detail below using embodiment examples.

Alloyed E1-E5 melts were melted according to the invention, the compositions of which are indicated in Table 1.

For the comparison, a comparison melt V1 was melted, the contents of C, Si, Mn, P, S and N corresponding to the conditions that apply to the known steel 38Si7, which, however, also still had Cr in an effective content. . Also the composition of the comparison melt V1 is indicated in Table 1.

Casting blocks were cast from the melts E1 - E5, V1, which were also previously and intermediately rolled conventionally to spring wires in several stages, before they were completely hot rolled in a final step. hot rolling stage. This last stage of hot rolling was carried out as thermomechanical rolling. To do this, the spring wire was cooled before entering the last stage of hot rolling to a temperature that was below the recrystallization stopping temperature of steels E1 - E5 and V1, which is at in this case in the range of 850 - 950 °C and above the Ar3 temperature of the steels E1 - E5 and V1, which in this case amounts to approximately 750 - 800 °C.

The recrystallization arrest temperature of the respective spring steel from which the respective spring wire E1 - E5, V1 has been generated, can be determined experimentally in a manner known per se or can be estimated with the help of empirically determined formulas.

Likewise, the temperatures Ar3 and Ar1 of the respective spring steel, from which the respective spring wire E1 - E5, V1 has been generated, can be determined experimentally in a manner known per se, for example by means of dilatometry in a simulator. thermomechanical.

After the end of the hot rolling, the hot-rolled spring wires obtained were cooled with a cooling rate of 1 - 5 °C/s to a winding temperature of 550 - 650 °C, at which they were wound. these to give a coil. The spring wires in the coil were then cooled to room temperature.

In the hot-rolled spring wires obtained, the fine granulation "ASTM_<f>" of the structure has been determined in accordance with the ASTM E112 standard and the breaking necking "Z_< in accordance with the DIN EN ISO 6892-1 standard. f>". The values obtained "ASTM_<f>" and "Z_<f>" are indicated in Table 2 for the spring wires that are made up of steels E1 - E5 and V1.

From the hot-rolled spring wires, which are made up of the spring steels E1 - E5, V1, bars have been cut off, which after pickling and straightening carried out in a conventional manner in several stages have been bent cold, that is, at temperature environment, to give a clamping clamp formed in a conventional way, in the shape of a u>.

After this cold forming, the clamping clips obtained were subjected to heat treatment, in which they were completely heated to an austenitic temperature of 850 - 950 °C, so that their structure was completely austenitic. The collets austenitized in this way were then quenched in water, so that their structure was more than 95% martensitic in surface area.

After sudden cooling, the clamping tongs were annealed, in which they were heated for a period of 60 - 120 min to an annealing temperature of 400 - 450 °C and held there. The clamping clips thus annealed were then cooled in air to room temperature.

In the clamping clips thus obtained, the tensile strength Rm and the elastic limit Rp0.2 have been determined in accordance with the DIN EN ISO 6892-1 standard. Furthermore, the energy absorbed during the KV-20 impact has been determined in accordance with the DIN EN ISO 148-1 standard as a characteristic value of toughness. The measurement values obtained are set out in Table 2. It was shown that not only the tensile strength Rm and the elastic limit Rp0.2 of the clamping clips generated in the manner according to the invention from spring steel The compound according to the invention could be clearly increased with energy absorbed during the impact KV-20 unchanged compared to the clamping clips made from the comparison steel V1, but in this respect the ratio Rm/ Rp0.2.

At the same time, the clamping clips generated from the spring steels E1 - E5 according to the invention had a "ASTM" fine graining of the structure, determined in accordance with the ASTM E112 standard, clearly better than the clamps from fastening that are made of comparison steel V1.

Subsequently, the clamping clamps consisting of the steels E1 -E5 according to the invention and the comparison steel V1 were used in the construction under identical conditions at a fixing point and the suppression forces exerted by them were determined. these in the new state "TLn" and after 3 million load changes "TL3m". The results of this measurement are also shown in Table 2. It is shown that the clamping clips which are made of the spring steels E1 - E5 according to the invention provide not only in the new state a higher clamping force TLn , but this suppression force is only insignificantly reduced even after 3 million load changes, while it decreases by a significantly greater magnitude in the case of the clamping tongs that are made of the comparison steel V1.

Table 1

Table 2

Claims (15)

1. Spring wire produced from a steel that is made up, by weight, of C: 0.35 - 0.42%, Yes: 1.5 - 1.8%, Mn: 0.5 - 0.8%, Cr: 0.05 - 0.25%, Nb: 0.020 - 0.10%, V: 0.020 - 0.10%, N: 0.0040 -0.0120% Al: <0.03%, and as the remainder iron and unavoidable impurities, where the content of the sum of the impurities is limited to a maximum of 0.2% and the impurities belong up to 0.025% of P and up to 0.025% of S. 2. Spring wire according to claim 1, characterized in that its C content amounts to a maximum of 0.40% by weight. 3. Spring wire according to one of the preceding claims, characterized in that its Cr content amounts to at least 0.1% by weight. 4. Spring wire according to claim 2, characterized in that its Cr content amounts to at least 0.18% by weight. 5. Spring wire according to one of the preceding claims, characterized in that its Mn content amounts to at least 0.6% by weight. 6. Spring wire according to claim 5, characterized in that its Mn content amounts to at least 0.7% by weight. 7. Spring wire according to one of the preceding claims, characterized in that its Nb content amounts to at least 0.030% by weight. 8. Spring wire according to one of the preceding claims, characterized in that its Nb content amounts to a maximum of 0.070% by weight. 9. Spring wire according to one of the preceding claims, characterized in that its V content amounts to a maximum of 0.060% by weight. 10. Spring wire according to one of the preceding claims, characterized in that its N content amounts to at least 0.0060% by weight. 11. Spring wire according to one of the preceding claims, characterized in that it achieves a breaking stress Z, determined in the tensile test according to DIN EN<i>S<o>6892-1, of at least 55%. 12. Spring wire according to one of the preceding claims, characterized in that the fine granulation of its structure, determined in accordance with the ASTM E112 standard, corresponds to at least ASTM 10. 13. Clamp for holding under a rail for rail vehicles at a rail fixing point produced from a spring wire provided according to one of the preceding claims. 14. Method for producing a spring wire provided according to one of claims 11 or 12 comprising the following working steps a) melt a steel, which is made up, in % by weight, of C: 0.35 - 0.42%, Si: 1.5 -1.8%, Mn: 0.50 - 0.80%, Cr : 0.05 - 0.25%, Nb: 0.020 - 0.10%, V: 0.020 - 0.10%, N: 0.0040 - 0.0120%, Al: < 0.03% and as remainder iron and unavoidable impurities, where the content of the sum of the impurities is limited to a maximum of 0.2% and the impurities include up to 0.025% P and up to 0.025% S; b) strain the steel to give a previous product; c) hot rolling the previous product to give a hot rolled spring wire with a final diameter of 9 -15 mm, wherein the hot rolling is carried out in at least two partial stages, wherein the spring wire is rolled hot rolling completely in the last partial stage of hot rolling thermomechanically at a temperature that is below the recrystallization arrest temperature of the spring wire steel and above the Ar3 temperature of the spring wire steel ; d) cooling the hot rolled spring wire completely thermomechanically with a cooling rate of 1 - 5 °C/s to a winding temperature of 550 - 650 °C; e) depositing or winding the spring wire cooled to the winding temperature to give a coil; f) cool the spring wire in the coil to room temperature. 15. Method according to claim 14, characterized in that the partial stages of hot rolling (working stage c)) are carried out in the continuous cycle.