EP2664682A1 - Steel for the production of a steel component, flat steel product comprising same, component comprised of same and method for producing same - Google Patents

Abstract

Steel comprises 0.05-0.15 wt.% of carbon, 0.5-2 wt.% of manganese, 0.01-0.70 wt.% of silicon, 0.01-0.1 wt.% of aluminum, 0.08-0.14 wt.% of titanium, 0.15-0.50 wt.% of chromium = 0.010 wt.% of sulfur and/or optionally one or more elements comprising = 0.1 wt.% of phosphorus, = 0.01 wt.% of nitrogen, = 0.1 wt.% of copper, = 0.1 wt.% of nickel, = 0.1 wt.% of molybdenum, = 0.1 wt.% of vanadium, = 0.0010 wt.% of boron, = 0.25 wt.% of niobium and 0.001-0.0040 wt.% of calcium, iron and unavoidable impurities. Independent claims are included for: (1) a flat steel product, comprising completely or at least in a portion of a constituted steel; (2) a steel component produced by hot-forming and subsequent quenching of the produced flat steel product, comprising the constituted steel having a tensile strength of at least 700 MPa and a structure, which consists of a combination of finely dispersed hard phases (martensite/bainite) and ductile phases (globular ferrite and dislocation-rich bainitic ferrite) and/or an austenite area of maximum of 5% in a fine-grained microstructure with additional precipitation hardening from titanium carbonitrides; and (3) producing the constituted steel component, comprising heating the flat steel product at a temperature of 750-950[deg] C in an oven, transferring the flat steel product from the oven to a tool, hot-forming the flat steel product into the steel component, and quenching the flat steel product at a cooling rate of more than 25[deg] C/seconds.

Description

The invention relates to a steel for the production of a steel component, a flat steel product consisting at least in sections of such a steel, a steel component produced from such a steel flat product by hot forming and quenching and a method for producing such a steel component.

In particular, the present invention relates to the use of steels having a ferritic / pearlitic / bainitic structure in the delivery state with precipitation hardening, for the production of press-hardened components in the strength range of about 700 to 1150 MPa.

The term "flat steel product" here by a rolling process produced steel sheets or steel strips and divided therefrom boards and the like understood.

If alloy contents are stated here only in "%", this always means "% by weight", unless expressly stated otherwise.

The demands on the automotive industry by the legislator have increased in recent years. On the one hand, increased passenger safety is required in the event of a crash. On the other hand, lightweight construction is an important prerequisite for compliance with the statutory CO ₂ limit values and for minimizing the energy required to drive the vehicle. At the same time, users of vehicles are placing ever greater demands on comfort, resulting in an increased share of electronic components in the vehicle and thereby increasing vehicle weight leads. In order to meet these conflicting requirements at the same time, the automotive industry and the upstream flat steel industry strive for lightweight construction in the manufacture of the body structure.

In particular, components which are produced by hot forming and subsequently hardening of flat steel products which consist of a manganese-boron steel have prevailed here for crash-relevant automotive components. By such a term in the jargon also referred to as "hot press hardening" manufacturing components can be produced, which can be used with optimally thin wall thickness and concomitantly minimized weight, for example, as B-pillars, B-pillar reinforcement and bumpers.

A typical example of a manganese-boron steel of the type mentioned above is the steel known in the art as 22MnB5, which has been given the material number 1.5528. Hot forming with subsequent press hardening makes it possible to produce components with complex geometries with optimum properties from steels of this type Create dimensional accuracy. Due to their predominantly martensitic structure, the components obtained by hot-pressing hardening have the highest strengths (Rm approx. 1500 MPa, R _P0 , ₂ approx. 1100 MPa) and thus have an optimized lightweight construction potential. However, as a price for the high strength low ductility (A80 about 5-6%) must be accepted. Therefore, in practice, the sheet thickness of the components is often made stronger for safety reasons than it would be necessary to avoid failure in the event of a crash. As a result, the lightweight potentials are not fully exploited.

One way around these disadvantages is the use of so-called "tailored blanks". Tailored blanks are blanks composed of at least two sheets. The sheets in question differ in at least one property. Thus, for example, in a certain section of the component to be formed from the respective tailored blank, a particularly high strength and at the same time comparatively low toughness can be provided, while in another section a reduced strength but increased toughness is available. For example, a Tailored Blank for a B-pillar may be designed so that, for example, the upper area associated with the roof of the vehicle to which high strength requirements apply is 22MnB5, while the area associated with the B-pillar foot is a steel grade exists, which has an increased ductility after curing. An example of a suitable steel for this purpose is steel H340LAD, to which the material number 1.0933 has been assigned. This steel reaches a Tensile strength of about 500 to 650 MPa at an elongation of about 15% after hot working.

A disadvantage of the solution explained in the preceding paragraph, that in the critical area (in the example chosen here, the B-pillar of a vehicle body, the lower portion of the column) due to the relatively low strength, a higher sheet thickness is necessary, resulting in a correspondingly higher weight for the entire component entails.

Another development towards partner material for tailored blanks is in the WO 2008/132303 Al described. This is a steel plate made of a microalloyed steel with an Al or Zn-based corrosion protection coating. After full austenitization and subsequent press hardening, it has a predominantly ferritic structure (> 75%) with lower levels of martensite (5-20%). and bainite (<10%). Restaustenitanteile in the structure are expressly undesirable. Components made from 0.5 - 4 mm thick steel blanks produced by this hot forming process have tensile strengths in the range of 500-600 MPa at elevated elongation values (> 15%). The improved ductility ensures a higher energy absorption capacity in the event of a crash.

From the DE 10 2006 019 395 A1 In addition, an apparatus and a method for press hardening of blanks of higher and ultrahigh - strength steels are known. The known device allows the control of the tool temperature during the forming process, whereby tailored tempering and hot forging can be performed. At the Tailored tempering only partially heats the dies during hot forming. The targeted temperature control produces locally a mixed structure with reduced strengths but improved ductility. Thus, in the later component in the event of a crash, the kinetic energy inherent in the respective vehicle at the moment of the accident can be dissipated as deformation energy.

In warm forging, the workpiece is heated to a temperature below the recrystallization temperature. The warming temperature for warm forging is typically in the range of 400-650 ° C. An example of a steel which is particularly suitable for hot forging is the steel known as "CP-W 800", which according to DIN EN 10336 is assigned the designation HDT780C. Conventional practice for the 22MnB5 steel subjected to phase transformation during press-hardening requires mold temperatures below 200 ° C to produce a martensitic structure after press-hardening.

Against the background of the prior art explained above, the object of the invention was to provide a steel which is optimally suitable for the production of components by hot-press hardening, a steel flat product also optimally suitable for hot-press hardening, a steel component in which high strength and high ductility are optimally achieved combined, and to provide a method for producing such a component.

With respect to the steel, this object has been achieved according to the invention in that such a steel has the composition specified in claim 1.

With regard to the flat steel product, the solution according to the invention of the abovementioned object is that such a flat steel product consists of a steel according to the invention.

With regard to the component, the above-mentioned object has been achieved according to the invention in that the component has the features specified in claim 11.

Finally, the solution of the above-mentioned object with respect to the method according to the invention is that in the production of a component according to the invention, the operations specified in claim 13 are performed.

Advantageous embodiments of the invention are specified in the dependent claims and are explained below as the general inventive concept in detail.

• C: 0,05 - 0,15 %,
• Mn: 0,5 - 2,0 %,
• Si: 0,01 - 0,70 %,
• Al: 0,01 - 0,1 %,
• Ti: 0,08 - 0,14 %,
• Cr: 0,15 - 0,50 %,
• S: ≤ 0,010 %,
• sowie jeweils optional eines oder mehrere Elemente aus der Gruppe "P, N, Cu, Ni, Mo V, B, Nb, Ca" mit der Maßgabe
  • P: ≤ 0,1 %,
  • N: ≤ 0,01 %,
  • Cu: ≤ 0,1 %,
  • Ni: ≤ 0,1 %,
  • Mo: ≤ 0,1 %,
  • V: ≤ 0,1 %,
  • B: ≤ 0,0010 %,
  • Nb: ≤ 0,25 %,
  • Ca: 0,001 - 0,0040 %.

A steel according to the invention for the production of a steel component by hot working with subsequent hardening accordingly contains, in addition to iron and unavoidable impurities (in% by weight)

• C: 0.05-0.15%,
• Mn: 0.5-2.0%,
• Si: 0.01-0.70%,
• Al: 0.01 - 0.1%,
• Ti: 0.08 - 0.14%,
• Cr: 0.15-0.50%,
• S: ≤ 0.010%,
• and in each case optionally one or more elements from the group "P, N, Cu, Ni, Mo V, B, Nb, Ca" with the proviso
  • P: ≤ 0.1%,
  • N: ≤ 0.01%,
  • Cu: ≦ 0.1%,
  • Ni: ≤ 0.1%,
  • Mo: ≤ 0.1%,
  • V: ≤ 0.1%,
  • B: ≤ 0.0010%,
  • Nb: ≤0.25%,
  • Ca: 0.001-0.0040%.

A flat steel product according to the invention accordingly consists, at least in one section, of a steel according to the invention.

The proviso that the flat steel product according to the invention consists of at least one section of a steel according to the invention includes, of course, the possibility that the flat steel product as a whole is made of a steel according to the invention. In this case, the at least one section of the flat steel product consisting of the steel according to the invention may be formed from a hot-rolled sheet or a sheet produced by conventional cold-rolling.

In particular, the flat steel product according to the invention can be a tailored blank, which is composed of at least two sheet metal parts which are themselves in addition to possibly existing differences in their areal extent in at least one property, such as thickness, strength, toughness, elongation properties, etc., distinguish.

The steel component according to the invention is produced by hot forming and subsequent quenching of a flat steel product according to the invention. In this case, the steel component has a tensile strength of at least 700 MPa in the region in which the steel obtained according to one of claims 1 to 5 has a structure consisting of a combination of finely divided hard phases (martensite / bainite ) and ductile phases (globular ferrite and dislocation-rich bainitic ferrite) and a residual austenite content of at most 5 area% in a fine-grained microstructure with additional precipitation hardening of titanium carbonitrides. At the same time, in the structure of the region of the steel component consisting of the steel according to the invention, the average grain diameter of the globular ferrite or of the bainitic ferrite is 1.5-4.0 μm and the proportion of ductile phases is at least 5 area%.

In the case of the steel component produced by hot forming and hardening of a steel flat product according to the invention, the structure consists of a combination of finely divided hard phases (martensite / bainite) and more ductile phases (bainitic ferrite and globular ferrite) and retained austenite with additional precipitation hardening by titanium carbonitrides. The proportion of ductile phases depends thereby directly from the C content and amounts to at least 5 area%.

The ferrite structure of the steel component according to the invention is extremely fine. The average grain diameter of the ferrite or bainitic ferrite here is 1.5-4.0 microns, which according to DIN EN 643 with a particle diameter of 4.0 microns a particle size index of at least 13 and with a particle diameter of 1.5 microns a grain size number> 15 corresponds.

The fine-grained microstructure means not only small grains but also a high number of phase boundaries in the steel component produced from the steel according to the invention by hot press hardening. These have a stronger effect on the tensile strength than the ferritic grain boundaries alone. The bainitic ferrite also has a high dislocation density. The fine structure and the high dislocation density contribute to the special mechanical and technological properties of the steel according to the invention, of a steel flat product consisting thereof and of a steel component produced therefrom.

• Bereitstellen eines gemäß einem der Ansprüche 6 bis 8 beschaffenen Stahlflachprodukts,
• Erwärmen des Stahlflachprodukts auf eine 750 - 950 °C betragende Erwärmungstemperatur in einem Ofen,
• Transfer des Stahlflachprodukts vom Ofen zu einem Werkzeug,
• in dem Werkzeug erfolgendes Warmumformen des Stahlflachprodukts zu dem Stahlbauteil,
• Abschrecken des Stahlflachprodukts mit einer Abkühlrate von mehr als 25 °C/s.

The method according to the invention for producing a steel component according to the invention comprises the following steps according to the above explanations:

• Providing a flat steel product obtained according to any one of claims 6 to 8,
• Heating the flat steel product to a heating temperature of 750-950 ° C in an oven,
• Transfer of the flat steel product from the furnace to a tool
• hot working the steel flat product into the steel component in the tool;
• Quenching the flat steel product with a cooling rate of more than 25 ° C / s.

In order to reliably avoid the excessively high temperature loss of the steel flat product heated according to the invention to the heating temperature during its transport to the hot forming tool, the transfer from the oven to the tool can be completed within 5 to 12 seconds.

The invention provides a steel and a flat steel product made therefrom which, after hot-pressing hardening, have a tensile strength which, at breaking elongation values A ₈₀ of 6 to 15%, are typically in the range from 700 to 1200 MPa, in particular 700 to 1150 MPa. In this way, the invention closes the gap between the materials with relatively low tensile strength and higher elongation at break (eg H340LAD) and materials with high tensile strength values and low elongation at break (eg 22MnB5). By means of the alloying concept predetermined according to the invention, it is possible to produce a steel component from a flat steel product according to the invention by hot forming with subsequent hardening, which is suitable for the respective conventional production method Requirement has optimal mechanical properties. These mechanical properties are reliably achieved over the entire process window defined by the invention. The stability of the mechanical and technological properties is ensured by the analysis concept of the steel according to the invention.

C is present in a steel according to the invention with a content of at least 0.05% by weight and at most 0.150% by weight, in particular 0.06-0.11% by weight, in order, on the one hand, to ensure that the final one Deterrence, the minimum tensile strength of 700 MPa required for steel components according to the invention forms necessary Martensithärte and on the other hand to avoid an excessive increase in hardness. Also, the C content is limited to a maximum of 0.150 wt .-%, so as not to affect the weldability of the steel component according to the invention. The range of tensile strength prescribed for the steel components according to the invention can be achieved particularly reliably if the C content of the steel is at least 0.08% by weight.

Mn in contents of 0.50-2.0% by weight serves as austenite former in the steel according to the invention by reducing the A _C3 temperature by its presence. The result is a high austenite content even at relatively low heating temperatures. To optimize the weldability of the Mn content can be lowered to a maximum of 1.20 wt .-%.

In amounts of 0.01-0.70 wt.%, Si acts as an oxidizing agent in the steel according to the invention on the one hand On the other hand, it has a positive effect on the mechanical properties. This is the case in particular if at least 0.20% by weight of Si are present in the steel according to the invention. Thus, the presence of Si in the limits specified by the invention increases the yield strength and stabilizes the ferrite and the austenite at room temperature. At the same time, Si prevents unwanted carbide precipitation in austenite during cooling. Excessive Si content causes surface defects.

Al in contents of 0.01-0.1 wt.%, In particular maximally 0.07 wt.%, Stabilizes the ferrite and the austenite at room temperature in steel according to the invention. At the same time, the size of the grains forming in the microstructure of the steel according to the invention can be controlled via the Al content. Accordingly, the formation of a particularly fine-grained microstructure contributes when the Al content of the steel according to the invention is at least 0.020% by weight.

In a steel according to the invention, Ti increases the yield strength and causes the formation of precipitates, which are present, for example, as titanium carbonitrides in a steel according to the invention. In addition, precipitation formation increases tempering resistance and improves toughness by inhibiting grain growth during furnace heating during hot working. In order to reduce possible dispersions of these positive influences by a high precipitation fraction, in particular of carbonitrides, a steel according to the invention contains relatively high Ti contents of 0.08-0.14% by weight, in particular at least 0.09% by weight.

Cr is contained in the steel according to the invention in amounts of 0.15-0.5% by weight in order to promote through-hardenability and thereby minimize the dependence on the cooling rate. In this way, steel according to the invention becomes less sensitive to possible fluctuations of the hot working parameters. However, in order to avoid surface defects on the finished steel component according to the invention, the Cr content must not exceed 0.5% by weight. The positive effects of the presence of Cr in a steel according to the invention can be used particularly reliably if the Cr content is 0.3-0.4% by weight.

The S-content of the steel according to the invention must not exceed 0.010% by weight, because otherwise problems in welding, in surface finishing and in the formation of harmful, elongated MnS precipitates are to be expected. Preferably, therefore, the S content of the steel according to the invention is as low as possible.

In addition to the mandatory ingredients C, Mn, Si, Al, Ti and Cr enumerated above, a steel according to the invention may optionally contain one or more of the elements selected in the group "P, N, Cu, Ni, Mo, V, B, Nb, Ca "are summarized. Each of these elements can have a positive benefit, but is not a compulsory component and can be dispensed with as such in order to be able to produce a steel component with the properties prescribed according to the invention by hot forming and subsequent hardening.

Also optionally in the steel according to the invention P may be present in amounts of up to 0.1 wt .-%. In combination with Si, P increases the stability of austenite. Too high a P content, however, damages the ductility and toughness of the steel.

In amounts of up to 0.01% by weight, N stabilizes the austenite in the steel according to the invention and increases the yield strength. In addition, the presence of N enables the desired formation of titanium carbonitrides according to the invention. If N is not completely bound by Ti and the steel according to the invention additionally contains B, N reacts in combination with boron to boron nitrides, which cause grain refining of the starting structure and thus a refining of the martensitic structure present in the finished steel component after hot working and hardening. In order to safely achieve these positive effects of the presence of N, the N content of the steel according to the invention may be set to at least 0.0025% by weight.

Cu can be used in the steel according to the invention to increase the yield strength. However, at levels above 0.1% by weight, the presence of Cu may affect the hot workability of the steel.

In amounts of up to 0.1% by weight, Ni can improve the yield strength and elongation at break of the steel of the present invention. In addition, contents are avoided for cost reasons.

Mo is optionally present in the steel of the present invention at levels of up to 0.1% by weight. Mo promotes martensite formation and improves toughness. Over 0.1% by weight However, exceeding Mo content may cause cold cracking in the steel according to the invention.

In amounts of up to 0.1% by weight, V increases the yield strength of the steel of the invention by grain refining and improves weldability.

By adding up to 0.001% by weight of B, the hardenability of the steel according to the invention can be improved. Here, by delaying ferrite transformation during cooling, B prolongs the transformation times and stabilizes the mechanical properties for a wide temperature range of the hot working process in terms of early, homogeneous martensite formation. However, amounts of B exceeding 0.0010% by weight markedly reduce the formability of the steel according to the invention.

Nb in amounts of up to 0.25% by weight increases the yield strength of the steel according to the invention by carbide precipitation and, by austenitic grain refining, produces a fine martensite structure which has a high resistance to crack propagation. These positive properties can be used in particular when the Nb content is at least 0.001% by weight, in particular at least 0.005% by weight.

Ca is optionally alloyed to a steel of the invention at levels of 0.001-0.004 wt%, especially 0.001-0.003 wt%, to allow sulfide form control through the formation of spherical CaS over MnS. In this way, the isotropy of the mechanical properties is improved. By a Ca-treatment of the melt of the Steel according to the invention can also reduce the S content of the steel according to the invention.

The flat steel product according to the invention may have a surface finish for protection against scaling or corrosion. The protective coating concerned can be applied by conventional methods. Preferably, the protective coating is applied in the hot dipping process and can contain zinc or aluminum in a conventional manner as a basic element. The basic elements Zn and Al may optionally be alloyed with each other or additionally each with one or more oxygen-affine elements such as Mg, Si, Ti, Ca, boron, Mn. Typical layer thicknesses of the protective coating are in the range 3-30 μm, preferably between 5-20 μm.

To improve the surface quality and the connection of the coating to the steel surface, the hot dip coating can be preceded by a preoxidation in which a 10 to 1000 nm, preferably 70 to 500 nm, thick oxide layer is produced on the flat steel product to be coated. The generation and adjustment of the oxide layer can take place in an oxidation chamber, as in the WO 2007/124781 A1 is described, the contents of which is included in the present application in this respect. The complete reduction of the iron oxide layer thus formed takes place under a hydrogen-containing atmosphere and is carried out before immersion in the melt or before surface refinement. Oxides of the alloying elements of the steel according to the invention can be present on the steel strip surface.

Alternatively or additionally, it is possible to anneal steel flat products according to the invention in continuous annealing plants and / or in a bell annealing plant and to coat them by means of a downstream off-line surface finishing plant. For this purpose, PVD / CVD processes, processes with electrolytic or electroless or chemical deposition of metallic coatings, in particular coatings based on Zn, Zn-Ni, Zn-Fe and their combinations, as well as processes in which organic, organometallic, inorganic Coatings are applied in coil coating systems in the coil coating, spraying or dipping process can be used.

Steel flat products according to the invention can be produced by casting a molten steel composite according to the invention into slabs or thin slabs, which are subsequently brought to a temperature of 1050.degree.-1260.degree. C., at a hot rolling end temperature of 800.degree.-1000.degree. C. to form a hot strip having a hot strip thickness of to be hot rolled less than 4.5 mm. The resulting hot strip is then coiled at a reel temperature of 450 - 700 ° C to form a coil.

Steel flat products according to the invention which are present as hot strip or sheet metal can produce steel components according to the invention in the same way as steel flat products according to the invention which are present as cold strip or sheet metal. In the case that the flat steel products are to be processed as a cold strip, this can be done following the hot strip production explained above hot rolled strip obtained is cold rolled to a cold strip having a thickness of typically 0.5 to 2.85 mm.

After an optional surface refinement, blanks are separated from the flat steel product then present as a strip. For the production of tailored blanks, these boards can be welded to at least one other board. Alternatively, the boards split off from the flat steel products produced according to the invention can also be processed as one piece into a steel component according to the invention.

For the production of the steel component, the flat steel product, which is now in the form of a single-piece blank or blanked blank, is heated to a heating temperature of 750-950 ° C. This leads to a complete or partial austenitization. The heating in accordance with the invention predetermined range of heating temperatures leads to a hot working and a press hardening to a microstructure, which consists of a combination of finely divided martensite and bainite phases, dislocation rich bainitic ferrite, globular ferrite and retained austenite. In addition, an additional precipitation hardening by titanium carbonitrides. The result is a fine and homogeneous phase distribution, which causes an improvement in the elongation values and an increase in energy absorption at relatively high tensile strength values. At the same time, a small residual austenite content of up to 5% is achieved, which also contributes to the improvement in elongation values. The proportion of ductile phases ferrite and bainitic ferrite is at least 5 area%.

Preferably, the respective flat steel product is heated in the hot forming and curing preceding heating to heating temperatures of up to 900 ° C, in which there is only a partial Austenitisierung. Surprisingly, it has been found that with such a heating after the hot working and the subsequent hardening, the resulting component has further improved strengths, as is the case with a full austenitization, which with a heating in the temperature range> 900 ° C, in particular> 925 ° C. is reached. This effect is due to the high Ti content of the steel according to the invention, which can be supported by the optionally additionally present contents of Nb and V. The presence of a larger amount of these micro-alloying elements, the grain size remains fine even during the heat treatment and hot working. For the grain size of the globular ferrite or the bainitic ferrite of a steel component according to the invention, as already mentioned, a particle size index of at least 13 determined according to DIN EN 643 is guaranteed here. The holding time required for the heating on the heating temperature is typically 2 to 10 minutes, depending on the dimension of the flat steel product to be processed.

After heating to the heating temperature, the heated steel flat product is transferred from the oven used for the heating to the tool in which the flat steel product is hot worked. The thermoforming tool can be designed in such a way that the steel component thermoformed from the flat steel product is still quenched in the tool (single-stage process). Alternatively it is However, it is also possible to quench the resulting steel component outside the thermoforming tool in a separate workstation to produce the desired hardness structure (two-stage process). To avoid excessive cooling of the steel flat product between the heating furnace and the thermoforming tool, the transfer time should be limited to 5 - 12 seconds.

The cooling of the steel component formed from the respective flat steel product preferably takes place in the hot forming tool so rapidly that the component structure after cooling consists of a fine-grained structure of martensite, bainite, dislocation-rich bainitic ferrite, globular ferrite and retained austenite. The required cooling rate is at least 25 ° C / s.

To demonstrate the effects achieved by the invention, three inventive steels E1, E2, E3 and four comparative steels V1, V2, V3, V4 were melted. The compositions of steels E1-E3 according to the invention and comparative steels V1-V4 are given in Table 1. In the case of the comparative melts V1-V4, the alloy contents in which the respective alloy deviates from the specifications according to the invention are identified by underscores. In addition, the respective Ac1 and Ac3 temperatures are indicated in Table 1 for the steels E1 - E3 and V1 - V4.

The molten steels E1 - E3 and V1 - V4 were cast into slabs, which were then hot rolled with a hot rolling end temperature WET to hot strip with a hot strip thickness WBD. The hot strip obtained was then coiled at a reel temperature HAT to a coil. The hot strips obtained after the coiling or optional annealing and coating, which consisted of the steels E2, E3 and V1 - V4, were then cold rolled with a cold rolling grade KG to cold strip with a cold strip thickness KBD. Then, for the cold strips consisting of the steels E2 and V2 - V4, annealing took place at an annealing temperature GT. The annealed cold strips E2 and V4 were then covered with an aluminum-silicon protective layer ("AS coating"), which protects the respective strip against corrosion.

Table 2 shows the hot rolling end temperature WET, the hot strip thickness WBD, the reel temperature HAT, the cold rolling degree KWG, the cold strip thickness KBD and the annealing temperature GT, among the hot and cold strips produced from the steels E1-E3 and V1-V4. Before the subsequent hot forming and hardening were thus produced from the steel E1 band as uncoated hot strip, produced from steel E2 band as annealed and provided with an AS coating cold strip, the bands produced from the steels E3 and V1 as cold rolling cold strips without coating, the strips produced from steels V2 and V3 as annealed cold-rolled strip without coating and the strip produced from steel V4 as annealed cold-rolled strip provided with an AS coating.

Of the 1.15 - 1.5 mm thick hot and cold strips produced from the steels E1 - E3 and V1 - V4, flat steel products in the form of boards intended for hot - press hardening were divided off.

The respective flat steel products were heated in an oven to a heating temperature EWT within a heating time EZ and then placed within a transfer time TZ in a thermoforming mold having a tool temperature WZT. Within the thermoforming tool, the flat steel products are each formed into a steel component and cooled at a cooling rate AKR.

Some of the components thus produced have subsequently been coated with a cathodic dip coating ("KTL coating"). In the case of cathodic dip coating, the associated heat treatment (customary simulation at 170 ° C./20 min.) Results in slight yield strength increases as a result of the so-called bake hardening effect ("BH effect"). It is noteworthy that there was no reduction in the tensile strength of the samples consisting of steels E1-E3 according to the invention. Also, increased mold temperature had no significant impact on the strength properties.

Tables 3 to 8 indicate the heating temperature EWT, the heating time EZ, the transfer time TZ, the cooling rate AKR of the quenching in the thermoforming mold and the tool temperature WZT for the steel components produced in the above-described manner. In addition, it is indicated in Table 3a whether the respective component has been subjected to a cathodic dip coating. Furthermore, in Tables 3 to 8, the average mechanical-technological values yield strength R _p0.2 , tensile strength R _m , uniform elongation Ag, elongation A ₈₀ , the content of the structure F / BF to ferrite and bainitic ferrite, the content of the structure RA of retained austenite, the content M of the microstructure of martensite, the content B of the microstructure of bainite and the ferrite grain size KG determined in accordance with DIN EN 643. In the case that the respective grain size has not been determined or could not be determined due to the extremely fine structure, this is indicated by the entry "---".

Tables 3 and 4 relate to steel components produced from the steels E1 (Table 3), E2 and E3 (Table 4) according to the invention, while Tables 5 to 8 consist of the comparative steels V1 (Table 5), V2 (Table 6), V3 (FIG. Table 7) and V4 (Table 8) relate to steel components produced. Table 1 C Si Mn P S al Cr Not a word N Ni Nb Ti B Ca Ac1 ac3 [Wt .-%] [° C] E1 0.073 0.60 1.73 0,015 0.001 0,040 0.34 0,020 0.0042 0.01 0.001 0.116 0.0005 0.0013 715 920 E2 0.067 0.58 1.75 0,010 <0.001 0,030 0.32 0,010 0.0030 0.05 0,010 0,100 0.0007 0.0015 715 920 E3 0.091 0.61 1.71 0.009 <0.001 0.032 0.32 0,006 0.0040 0.05 0, 008 0,100 0.0006 0.0015 715 915 V1 0.083 0.08 1.54 0,010 0,002 0,025 0.08 0,010 0.0047 0.03 0.037 0.001 0.0005 0.0012 735 870 V2 0.156 0.27 1.83 0,012 <0.001 0.033 0.55 0,070 0.0040 0.06 0,004 0,040 0.0013 0.0020 720 875 V3 0.064 0.35 0, 99 0,018 0,004 0.047 0.03 0,002 0.0050 0.02 0.027 0,003 0.0003 0.0040 720 915 V4 0,241 0.24 1.22 0,013 0,002 0,038 0.15 0,002 0.0033 0.02 0,003 0,038 0.0024 0.0001 720 845 Table 2 WBD [mm] KBD [mm] KWG [%] WET [° C] HAS [° C] GT [° C] E1 1.50 ---- --- 895 500 --- E2 2.05 1.50 27 890 500 780 E3 2.40 1.15 52 940 530 --- V1 3.06 1.50 51 865 470 --- V2 2.50 1.20 52 900 560 800 V3 4.04 1.50 63 885 630 810 V4 3.40 1.50 56 850 560 760 Table 3 (RT = room temperature) EWT EZ TZ AKR WZT KTL R _{p0 , 2} R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [ - ] E1 880 6 5 30 RT NO 489 795 8.5 11.5 84.5 1.5 14 > 15 E1 880 6 5 30 RT YES 529 784 7.0 14.2 84.5 1.5 14 > 15 E1 880 6 5 30 200 NO 481 770 8.8 13, 9 85 3.0 12 > 15 E1 880 6 5 30 200 YES 507 768 8.1 13.7 85 3.0 12 > 15 E1 880 6 5 80 RT NO 499 799 7, 6 11.3 91 <1 9 > 15 E1 880 6 5 80 RT YES 563 803 8.6 13, 4 91 <1 9 > 15 E1 880 6 5 80 200 NO 489 762 8.1 13.5 92 2.0 6 15 E1 880 6 5 80 200 YES 515 769 8.1 11.9 92 2.0 6 15 E1 880 6 15 30 RT NO 489 772 7, 6 12, 9 92 1.0 7 15 E1 880 6 15 30 RT YES 532 775 8.1 14, 9 92 1.0 7 15 E1 880 6 15 30 200 NO 482 754 8.3 15.1 91.5 1.5 7 15 E1 880 6 15 30 200 YES 516 768 8, 6 14.5 91.5 1.5 7 15 E1 880 6 15 80 RT NO 478 780 8.5 13.1 91 <1 9 13 E1 880 6 15 80 RT YES 533 780 8.5 13.4 91 <1 9 13 E1 880 6 15 80 200 NO 497 769 7.2 13.1 76 <1 24 14 E1 880 6 15 80 200 YES 527 768 7.8 13.4 76 <1 24 14 E1 925 6 5 30 RT NO 419 756 9, 6 15.4 75 2.0 23 14 E1 925 6 5 30 RT YES 453 755 10.5 14, 9 75 2.0 23 14 E1 925 6 5 30 200 NO 417 736 10.5 15.8 77.5 2.5 20 14 E1 925 6 5 30 200 YES 462 754 9.8 15.4 77.5 2.5 20 14 E1 925 6 5 80 RT NO 523 843 7.3 10.2 77.5 1.5 21 14 E1 925 6 5 80 RT YES 508 792 8.0 12.7 77.5 1.5 21 14 E1 925 6 5 80 200 NO 570 803 6.0 10.1 78 3.0 19 14 E1 925 6 5 80 200 YES 510 786 7.8 12.3 78 3.0 19 14 E1 925 6 15 30 RT NO 365 701 12.7 18.5 88.5 2.5 9 13 E1 925 6 15 30 RT YES 393 698 13.1 18.5 88.5 2.5 9 13 E1 925 6 15 30 200 NO 369 704 12.9 17, 5 87 3.0 10 13 E1 925 6 15 30 200 YES 388 690 12.2 17.4 87 3.0 10 13 E1 925 6 15 80 RT NO 384 708 12.4 17.4 84.5 1.5 14 13 E1 925 6 15 80 RT YES 418 723 11.9 17.2 84.5 1.5 14 13 E1 925 6 15 80 200 NO 378 698 12.0 18.0 83 2.0 15 13 E1 925 6 15 80 200 YES 408 702 12.6 19.2 83 2.0 15 13 Table 4 (RT = room temperature) stole EWT EZ TZ AKR WZT KTL R _p0,2 R _m Ag A ₈₀ F / BF RA M / B KG [° C] [Min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] E2 750 6 7 ≥100 RT NO 885 1053 4.5 7.1 1 68 <1 32 --- E2 750 6 7 ≥100 RT YES 918 1047 4.4 6.3 68 <1 32 --- E2 750 6 7 ≥100 200 NO 842 1026 4, 9 7.1 88 <1 12 --- E2 750 6 7 ≥100 200 YES 889 1023 4, 6 6.5 88 <1 12 --- E2 780 6 7 ≥100 RT NO 777 998 5.2 8th 47 <1 53 --- E2 780 6 7 ≥100 RT YES 829 993 5 7.4 47 <1 53 --- E2 780 6 7 ≥100 200 NO 775 988 5.4 7.5 79 <1 21 --- E2 780 6 7 ≥100 200 YES 824 982 5.4 7.8 79 <1 21 --- E2 880 6 7 ≥100 RT NO 509 813 9, 9 15, 6 58.5 1.5 40 15 E2 880 6 7 ≥100 RT YES 569 806 9.7 15.6 58.5 1.5 40 15 E2 880 6 7 ≥100 200 NO 592 822 8th 12.9 69 1 30 15 E2 880 6 7 ≥100 200 YES 623 816 8.1 13.2 69 1 30 15 E2 925 6 7 ≥100 RT NO 557 830 8.3 13.9 59 1 40 15 E2 925 6 7 ≥100 RT YES 621 831 7.7 13.1 59 1 40 15 E2 925 6 7 ≥100 200 NO 620 840 7.1 11.6 48.5 1.5 50 15 E2 925 6 7 ≥100 200 YES 657 842 6, 6 11.5 48.5 1.5 50 15 E3 880 6 7 ≥100 RT NO 541 958 9.5 13.5 31.5 2.5 66 14-15 E3 880 6 7 ≥100 RT YES 658 948 9.1 12.8 31.5 2.5 66 14-15 E3 880 6 7 ≥100 200 NO 684 982 6.2 9.9 20.5 3.5 76 14-15 E3 880 6 7 ≥100 200 YES 759 985 6, 9 10.5 20.5 3.5 76 14-15 E3 925 6 7 ≥100 RT NO 704 1038 5.4 8th 4.5 1.5 94 > 15 E3 925 6 7 ≥100 RT YES 834 1044 5.1 7.7 4.5 1.5 94 > 15 E3 925 6 7 ≥100 200 NO 757 1019 5.1 8.2 10 3 87 > 15 E3 925 6 7 ≥100 200 YES 819 1021 5.7 8, 6 10 3 87 > 15 Table 5 (RT = room temperature; * = not according to the invention) EWT [ _° C] EZ [min] TZ [s] AKR [° C / s] WZT [° C] KTL YES / NO R _{p0 , 2} R _m Ag A ₈₀ F / BF RA M / B KG stole [MPa] [%] [Area%] [-] V1 * 880 6 5 30 RT NO 382 675 11.5 19.4 75 5 20 15 V1 * 880 6 5 30 RT YES 408 673 13.2 18.4 75 5 20 15 V1 * 880 6 5 30 200 NO 365 650 14.5 19.6 73.5 4.5 22 15 V1 * 880 6 5 30 200 YES 420 653 14, 6 22.3 73.5 4.5 22 15 V1 * 880 6 5 80 RT NO 455 778 10.7 14.7 76.5 4.5 19 15 V1 * 880 6 5 80 RT YES 534 752 9.8 13.6 76.5 4.5 19 15 V1 * 880 6 5 80 200 NO 469 681 8.7 12.7 8.5 2.5 89 --- V1 * 880 6 5 80 200 YES 474 694 10.8 17, 6 8.5 2.5 89 --- V1 * 880 6 15 30 RT NO 326 683 14.7 20.1 86.5 3.5 10 14 V1 * 880 6 15 30 RT YES 388 669 13.3 18.6 86.5 3.5 10 14 V1 * 880 6 15 30 200 NO 316 660 14, 1 20 86.5 4.5 11 14 V1 * 880 6 15 30 200 YES 355 645 14, 6 20.6 86.5 4.5 11 74 V1 * 880 6 15 80 RT NO 366 733 12.8 18 87 3 10 14 V1 * 880 6 15 80 RT YES 578 803 7.1 12.8 87 3 10 14 V1 * 880 6 15 80 200 NO 352 709 11, 9 16.8 87 4 9 14 V1 * 880 6 15 80 200 YES 400 692 10.8 17.2 87 4 9 14 V1 * 925 6 5 30 RT NO 417 722 11.4 16.2 56.5 3.5 40 15 V1 * 925 6 5 30 RT YES 530 731 8, 9 14, 6 56.5 3.5 40 15 V1 * 925 6 5 30 200 NO 407 650 10.4 16.6 51.5 2.5 46 - V1 * 925 6 5 30 200 YES 438 652 10.5 18, 9 51.5 2.5 46 - V1 * 925 6 5 80 RT NO 515 797 7.6 11.7 8.5 1.5 90 - V1 * 925 6 5 80 RT YES 666 829 5.5 8.7 8.5 1.5 90 - V1 * 925 6 5 80 200 NO 479 677 9.3 16 8th 1 91 - V1 * 925 6 5 80 200 YES 524 700 8.2 14.8 8th 1 91 - V1 * 925 6 15 30 RT NO 350 706 12.4 16.4 77.5 2.5 20 13 V1 * 925 6 15 30 RT YES 412 677 8.2 18.4 77.5 2.5 20 13 V1 * 925 6 15 30 200 NO 323 657 11.5 18.1 75 3 22 14 V1 * 925 6 15 30 200 YES 367 662 11.5 18.2 75 3 22 14 Continuation of Table 5 (RT = room temperature; * = not according to the invention) EWT EZ TZ AKR WZT KTL R _p0 , ₂ R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] V1 * 925 6 15 80 RT NO 452 808 9.1 13.2 74 2 24 14 V1 * 925 6 15 80 RT YES 486 755 9, 9 18.2 74 2 24 14 V1 * 925 6 15 80 200 NO 377 727 9.6 13.4 75 3 22 14 V1 * 925 6 15 80 200 YES 496 731 8.2 14.1 75 3 22 14 Table 6 (RT = room temperature; * = not according to the invention) EWT EZ TZ AKR WZT KTL R _p0 , ₂ R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] V2 * 750 6 7 ≥ 100 RT NO 654 1241 7, 1 10.8 19 <1 81 14 V2 * 750 6 7 ≥ 100 RT YES 775 1210 5.2 8, 9 19 <1 81 14 V2 * 750 6 7 ≥ 100 200 NO 621 1200 6.8 10.5 17.5 1.5 81 15 V2 * 750 6 7 ≥ 100 200 YES 734 1195 6.3 10 17.5 1.5 81 15 V2 * 780 6 7 ≥ 100 RT NO 865 1353 5 8.3 10 <1 90 15 V2 * 780 6 7 ≥ 100 RT YES 1045 1346 4.1 1 6.8 10 <1 90 15 V2 * 780 6 7 ≥ 100 200 NO 750 1296 5.4 8.2 11 <1 89 15 V2 * 780 6 7 ≥ 100 200 YES 909 1287 4.8 7, 6 11 <1 89 15 V2 * 880 6 7 ≥ 100 RT NO 1003 1401 4 6.1 0 <1 99 --- V2 * 880 6 7 ≥ 100 RT YES 1148 1380 3.6 5.4 0 <1 99 --- V2 * 880 6 7 ≥ 100 200 NO 999 1369 4.2 6 0 <1 99 --- V2 * 880 6 7 ≥ 100 200 YES 1046 1355 4 5, 4 0 <1 99 --- V2 * 925 6 7 ≥ 100 RT NO 994 1368 3.9 5.9 0 <1 99 --- V2 * 925 6 7 ≥ 100 RT YES 1089 1358 3.7 5, 8 0 <1 99 --- V2 * 925 6 7 ≥ 100 200 NO 972 1339 4 5.7 0 <1 99 --- V2 * 925 6 7 ≥ 100 200 YES 1048 1332 4 5.4 0 <1 99 --- Table 7 (RT = room temperature; * = not according to the invention) EWT EZ TZ AKR WZT KTL R _{p0 , 2} R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] V3 * 880 6 5 30 RT NO 323 561 17.4 23.9 90 3 7 12 V3 * 880 6 5 30 RT YES 316 543 18.2 26.9 90 3 7 12 V3 * 880 6 5 30 200 NO 299 530 16.9 25.2 89.5 3.5 7 12-13 V3 * 880 6 5 30 200 YES 322 522 18, 6 26.1 89.5 3.5 7 12-13 V3 * 880 6 5 80 RT NO 357 608 14, 1 20.3 89 2 9 12-13 V3 * 880 6 5 80 RT YES 372 583 16.1 23.9 89 2 9 12-13 V3 * 880 6 5 80 200 NO 318 554 15.7 24 90 2 8th 12 V3 * 880 6 5 80 200 YES 348 561 14.5 22.4 90 2 8th 12 V3 * 880 6 15 30 RT NO 322 548 18.2 24.8 90.5 3.5 6 12 V3 * 880 6 15 30 RT YES 312 530 19.4 27, 9 90.5 3.5 6 12 V3 * 880 6 15 30 200 NO 307 532 18, 5 23.9 90.5 3.5 6 12 V3 * 880 6 15 30 200 YES 314 521 19 28.2 90.5 3.5 6 12 V3 * 880 6 15 80 RT NO 351 604 15.6 21.6 86 3 11 12-13 V3 * 880 6 15 80 RT YES 340 555 15, 9 23.5 86 3 11 12-13 V3 * 880 6 15 80 200 NO 307 564 17.7 24.1 89 3 8th 12-13 V3 * 880 6 15 80 200 YES 324 541 15.7 24, 9 89 3 8th 12-13 V3 * 925 6 5 30 RT NO 318 589 12, 8 18, 6 81.5 2.5 16 12 V3 * 925 6 5 30 RT YES 326 569 15.3 24.3 81.5 2.5 16 12 V3 * 925 6 5 30 200 NO 291 548 16.8 23.4 80.5 2.5 17 12 V3 * 925 6 5 30 200 YES 304 524 17.3 26.5 80.5 2.5 17 12 V3 * 925 6 5 80 RT NO 364 650 13 18.3 79 2 19 12 V3 * 925 6 5 80 RT YES 378 602 13, 4 21.6 79 2 19 12 V3 * 925 6 5 80 200 NO 332 581 12.9 20.1 84 3 13 12-13 V3 * 925 6 5 80 200 YES 339 566 14 22.1 84 3 13 12-13 V3 * 925 6 15 30 RT NO 291 572 13.9 19.1 92.5 2.5 5 12 V3 * 925 6 15 30 RT YES 288 532 18.5 27.4 92.5 2.5 5 12 V3 * 925 6 15 30 200 NO 271 548 15 20.9 87.5 2.5 10 12 V3 * 925 6 15 30 200 YES 290 538 18.4 26.8 87.5 2.5 10 12 Continuation Table 7 (RT = room temperature; * = not according to the invention) EWT EZ TZ AKR WZT KTL R _p0,2 R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] V3 * 925 6 15 80 RT NO 328 605 15.2 20.3 85 2 13 12 V3 * 925 6 15 80 RT YES 313 561 15.5 24.2 85 2 13 12 V3 * 925 6 15 80 200 NO 299 570 17.7 24, 6 79.5 1.5 19 13 V3 * 925 6 15 80 200 YES 316 559 15, 9 22.8 79.5 1.5 19 13 Table 8 (RT = room temperature; * = not according to the invention) EWT EZ TZ AKR WZT KTL R _p0,2 R _m Ag A ₈₀ F / BF RA M / B KG stole [° C] [min] [s] [° C / s] [° C] YES NO [MPa] [%] [Area%] [-] V4 * 750 6 7 ≥ 100 RT NO 522 1197 6, 6 9 44.5 4.5 51 13 V4 * 750 6 7 ≥ 100 RT YES 553 1153 6, 6 10, 6 44.5 4.5 51 13 V4 * 750 6 7 ≥ 100 200 NO 536 1189 9.1 11.4 42.5 3.5 54 14 V4 * 750 6 7 ≥ 100 200 YES 561 1162 8, 6 11.5 42.5 3.5 54 14 V4 * 780 6 7 ≥ 100 RT NO 775 1378 5, 5 7.8 37.5 2.5 60 14 V4 * 780 6 7 ≥ 100 RT YES 862 1359 5.3 6, 9 37.5 2.5 60 14 V4 * 780 6 7 ≥ 100 200 NO 814 1385 5.7 7.7 24 2 74 14 V4 * 780 6 7 ≥ 100 200 YES 933 1380 4.9 7 24 2 74 14 V4 * 880 6 7 ≥ 100 RT NO 1042 1543 3, 9 5.5 0 1.5 98.5 --- V4 * 880 6 7 ≥ 100 RT YES 1166 1549 3.8 5.6 0 1.5 98.5 --- V4 * 880 6 7 ≥ 100 200 NO 974 1510 4.3 5.9 0 2 98 --- V4 * 880 6 7 ≥ 100 200 YES 1072 1510 4 5.7 0 2 98 --- V4 * 925 6 7 ≥ 100 RT NO 1038 1527 4 5, 9 0 1 99 --- V4 * 925 6 7 ≥ 100 RT YES 1160 1523 3.8 5.9 0 1 99 --- V4 * 925 6 7 ≥ 100 200 NO 1022 1488 4 5.7 0 1 99 --- V4 * 925 6 7 ≥ 100 200 YES 1073 1492 4.2 6, 6 0 1 99 ---

Claims (15)

Steel for the manufacture of a steel component by hot forming followed by hardening, containing in addition to iron and unavoidable impurities (in% by weight) C: 0.05-0.15%, Mn: 0.5-2.0%, Si: 0.01-0.70%, Al: 0.01 - 0.1%, Ti: 0.08 - 0.14%, Cr: 0.15-0.50%, S: ≤ 0.010%, and in each case optionally one or more elements from the group "P, N, Cu, Ni, Mo V, B, Nb, Ca" with the proviso P: ≤ 0.1%, N: ≤ 0.01%, Cu: ≦ 0.1%, Ni: ≤ 0.1%, Mo: ≤ 0.1%, V: ≤ 0.1%, B: ≤ 0.0010%, Nb: ≤0.25%, Ca: 0.001-0.0040%. Steel according to claim 1, characterized in that its C content is 0.06 - 0.11 wt .-%. Steel according to one of the preceding claims,
characterized in that its C content is 0.08 - 0.11 wt .-%. Steel according to one of the preceding claims,
characterized in that its Ti content is greater than or equal to 0.09 wt .-%. Steel according to one of the preceding claims,
characterized in that its Cr content is 0.3-0.4% by weight. Flat steel product, by
in that it consists entirely or at least in one section of a steel obtained according to one of claims 1 to 5. Flat steel product according to claim 6, characterized in that it consists entirely of the steel obtained according to one of claims 1 to 5. Flat steel product according to one of claims 6 or 7, characterized in that at least the one according to one of claims 1 to 5 obtained steel existing portion of the flat steel product is formed by a hot rolled sheet. Flat steel product according to either of Claims 6 and 7, characterized in that at least the portion of the flat steel product made from the steel obtained according to one of Claims 1 to 5 is formed by a cold-rolled sheet. Flat steel product according to claims 6 to 9,
characterized in that it is provided at least on one of its surfaces with a protective coating against corrosion or scaling. A steel component produced by hot working and subsequent quenching of a flat steel product produced according to any one of claims 6 to 10, wherein the steel component has a tensile strength of at least 700 MPa and a microstructure in the region in which the steel obtained according to any one of claims 1 to 5 is made comprising a combination of finely divided hard phases (martensite / bainite) and ductile phases (globular ferrite and dislocation-rich bainitic ferrite) and a residual austenite content of not more than 5 area% in a fine-grained microstructure with additional precipitation hardening Titanium carbonitrides in which the average grain diameter of the globular ferrite or the bainitic ferrite is 1.5-4.0 μm and the proportion of ductile phases is at least 5 area%. Steel component according to claim 11, characterized in that in the region in which it consists of the steel obtained according to one of claims 1 to 5, the martensite / bainite content of the microstructure is at least 5 area%. A method of producing a steel component according to one of claims 11 or 12, comprising the following steps: Providing a flat steel product obtained according to one of claims 6 to 8, Heating the flat steel product to a heating temperature of 750-950 ° C. in an oven, Transfer of the flat steel product from the furnace to a tool, hot-working the steel flat product into the steel component in the tool, Quenching the steel flat product at a cooling rate of more than 25 ° C / s. A method according to claim 13, characterized in that the transfer from the oven to the tool is completed within 5 - 12 seconds. Method according to one of claims 13 or 14, characterized in that the heating temperature is <900 ° C.