Method and device for heat treating of a component of steel

Description

[0001] The invention relates to a method and a device for the heat treatment of a component made of steel.

[0002] The invention is particularly applicable to the partial hardening of optionally pre-coated components made preferably of a high-strength manganese-boron steel.

[0003] To manufacture safety-relevant vehicle body components from sheet steel, it is regularly necessary to harden the sheet steel during or after forming it into the body component. A heat treatment process known as "press hardening" has become established for this purpose. In this process, the sheet steel, which is usually supplied in the form of a blank, is first heated in an oven and then cooled and hardened during forming in a press.

[0004] Heating and press hardening regularly result in a (albeit slight) geometric change in the component compared to its unheated state. This typically necessitates trimming the steel sheet to the desired final contour after press hardening. Subsequent trimming can generally only be omitted if the tolerance specifications for the component being manufactured are such that this change remains within acceptable tolerances. However, in typical press hardening applications, the permissible tolerances are often tighter.

[0005] Furthermore, it must be considered that after press hardening, the steel sheets typically have a tensile strength of more than 1000 MPa (megapascals). Therefore, the hardened components can only be cut using special processes. One generally applicable method is so-called hard cutting. However, this requires tools capable of cutting through steel with a tensile strength exceeding 1000 MPa. On the one hand, hard cutting lengthens the production chain, and on the other hand, the necessary tools involve high investment costs, are subject to significant wear, and require intensive maintenance. Therefore, hard cutting has not proven practical in industrial mass production.

[0006] Laser cutting is a common method in industrial mass production. In this process, hardened components are cut to the desired final contour using at least one laser beam. However, laser cutting has the disadvantage of regularly resulting in long cycle times, high energy costs, and high investment costs.

[0007] Methods for manufacturing metallic components are known, for example, from DE 10 2009 050 623 A1, DE 102 08 216 C1, and EP 1 715 066 A1. US 2015 / 299817 A1 discloses a method in which a first heating step is followed by partial cooling and then a second heating step. DE 10 2010 049205 A1 discloses a hot forming line for hot forming sheet-shaped material and a method for hot forming sheet-shaped material designed as a blank or strip. WO2010150683A1 discloses a method for hot forming.

[0008] Based on this, the object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, a method and a device for the heat treatment of a metallic component are to be provided, which enable the production of a press-hardened component with the most precise contours possible in industrial series production. Furthermore, the method and the device should be as energy-efficient and / or as cost-effective to implement and manufacture as possible. In addition, the method and the device should, in particular, allow for the shortest possible cycle time.

[0009] These problems are solved by the features of the independent claims. The inventive method for heat-treating a steel component is defined in independent method claim 1.

[0010] The device according to the invention for the heat treatment of a component made of steel is defined in independent device claim 6.

[0011] Further advantageous embodiments of the solution proposed here are specified in the dependent claims. It should be noted that the features listed individually in the dependent claims can be combined in any technologically meaningful way and define further embodiments of the invention. Furthermore, the features specified in the claims are further detailed and explained in the description, which presents further preferred embodiments of the invention.

[0012] An inventive method for the heat treatment of a steel component comprises at least the following steps, which are carried out in the specified order: a) Heating the component, b) Setting a temperature difference of at least 50 K between at least one first section and at least one second section of the component, b') Introducing heat energy into the entire component by means of radiant heat, c) At least partially forming and / or cooling the component in a press hardening tool, d) Mechanical post-processing of at least one first section of the component, wherein the temperature difference in step b) is set by cooling the at least one first sub-area and / or heating the at least one second sub-area, and wherein the at least one first sub-area to be reworked has a lower strength compared to the at least one second sub-area before step d) and at the time of mechanical rework.

[0013] The indicated sequence of process steps a), b), b'), c), and d) results from a single execution of the process. The process is preferably carried out using the device presented here. The proposed method serves to produce a press-hardened component with the most precise contours possible.

[0014] The proposed method advantageously enables the production of press-hardened components with highly precise contours in industrial series production. This is achieved primarily by subjecting the component to partially differentiated heat treatment before post-processing, such that a section of the component requiring post-processing has a lower strength than at least one other section. This offers the advantage that post-processing can be carried out mechanically, particularly without high tool wear, thus eliminating the need for energy- and capital-intensive laser cutting. Mechanical post-processing can be performed relatively quickly, allowing the method to achieve particularly short cycle times.

[0015] The metallic component made of steel is preferably a blank, a sheet of steel, or a semi-finished product that is at least partially pre-formed. The metallic component is made of a (hardenable) steel, for example, a boron-(manganese) steel, e.g., designated 22MnB5. More preferably, the component is provided with a (metallic) coating or pre-coated, at least to a large extent. The metallic coating can be, for example, a coating containing (primarily) zinc or a coating containing (primarily) aluminum and / or silicon, in particular a so-called aluminum / silicon (Al / Si) coating.

[0016] In step a), the (entire) component is heated, in particular in a first furnace. Preferably, the component is heated homogeneously, uniformly, and / or evenly in the first furnace. More preferably, the component is heated (exclusively) in the first furnace by means of radiant heat, for example, from at least one electrically operated heating element (not in physical and / or electrical contact with the component), such as a heating loop and / or a heating wire, and / or from at least one (gas-heated) radiant tube.

[0017] In an advantageous embodiment, it is proposed that the component in step a) is heated by at least 500 K [Kelvin], preferably by at least 700 K or even by at least 800 K, by means of radiant heat and / or convection. Preferably, the heating in step a) is contactless, in particular without thermally conductive or electrical contact with an electrically operated heating element.

[0018] Preferably, in step a), the component is heated to a temperature below the AC3 temperature or even below the AC1 temperature. The AC1 temperature is the temperature at which the microstructure transformation from ferrite to austenite begins when a steel component is heated. The AC3 temperature is the temperature at which the microstructure transformation from ferrite to austenite ends or is (completely) completed when a steel component is heated. Alternatively, the component can be heated to a temperature above the AC3 temperature in step a).

[0019] Preferably, the component is moved to a temperature control station after step a) and before step b). A transport device, for example comprising at least a roller table and / or an (industrial) robot, may be provided for this purpose. Particularly preferably, the component is moved from a first furnace to a temperature control station. In particular, the component travels a distance of at least 0.5 m [meters] from the first furnace to the temperature control station. During this process, the component may be moved in contact with ambient air or within a protective atmosphere.

[0020] According to the invention, the temperature difference is set in step b) by cooling the at least one first sub-area and / or heating the at least one second sub-area. Preferably, in step b), partial, active, conductive and / or convective cooling of the at least one first sub-area of ​​the component is carried out, particularly in a temperature control station. After cooling, the component has partially different (component) temperatures, with a temperature difference being set between a first temperature of the at least one first sub-area and a second temperature of the at least one second sub-area of ​​the component. Furthermore, several (different) temperature differences between sub-areas of the component can be set in step b). For example, it is possible to set three or more sub-areas in the component, each with a different temperature.

[0021] Preferably, the temperature difference in step b) is set such that the (first) temperature of the at least one first sub-section of the component is lower than the (second) temperature of the at least one second sub-section of the same component. In step b), a temperature difference of at least 50 K, preferably at least 100 K or even at least 150 K, is set between the at least one first sub-section and at least one second sub-section of the component. The first sub-section is typically a more ductile sub-section in the finished component or a sub-section that has a lower strength (compared to the second sub-section). The second sub-section is typically a harder sub-section in the finished component or a sub-section that has a higher strength (compared to the first sub-section).

[0022] If, in step b), (active) cooling of the at least one first sub-area is provided, this is preferably carried out convectively, and particularly preferably by means of at least one nozzle discharging a fluid. For this purpose, the nozzle can be arranged in the temperature control station and directed towards the first sub-area. The fluid can be, for example, air, nitrogen, water, or a mixture thereof. Preferably, the cooling is carried out by means of a nozzle array with several nozzles, each discharging a fluid, wherein the shape of the nozzle array and / or the arrangement of the several nozzles is particularly preferably adapted to the (to be achieved) geometry of the at least one first sub-area of ​​the component.

[0023] Preferably, the at least one first sub-section in step b) is cooled to a temperature below the AC1 temperature. Particularly preferably, the at least one first sub-section in step b) is actively cooled to a temperature below the AC1 temperature. More preferably, the at least one first sub-section in step b) is cooled to a temperature below 550°C (823.15 K), particularly preferably below 500°C (773.15 K), or even below 450°C (723.15 K).

[0024] As an alternative to (active) cooling of the at least one first sub-area, the temperature difference between the at least one first sub-area and the at least one second sub-area of ​​the component can also be adjusted by at least partially thermally insulating, separating, demarcating, and / or sealing off the at least one first sub-area. Preference is given to thermally insulating, separating, demarcating, and / or sealing off the at least one first sub-area from the at least one second sub-area and / or from a heat source, such as an (electric) heating element, at least partially, particularly by means of at least one cover, panel, and / or partition.Particularly if the first sub-section of the component is not actively cooled, it is especially preferred that in step b) at least a third sub-section of the component is actively cooled, for example convectively and / or conductively, and / or that thermal energy is (actively) introduced into the second sub-section of the component. This allows for an even lower strength to be achieved in the third sub-section than in the first sub-section. Preferably, in step b), at least a third sub-section of the component is cooled by at least 50 K, more preferably by at least 100 K, or even by at least 150 K.

[0025] Preferably, in step b), particularly in a temperature control station and / or simultaneously or at least partially in parallel with (active) cooling or passive cooling or allowing the at least one first sub-area of ​​the component to cool down, heat energy is introduced into the at least one second sub-area of ​​the component. Preferably, during step b) and / or in the temperature control station, the at least one second sub-area of ​​the component is (exclusively) exposed to thermal radiation, which is generated and / or emitted, for example, by at least one electrically operated or heated heating element (not in contact with the component), such as a heating loop and / or a heating wire, and / or by at least one (gas-heated) radiant tube, particularly in the temperature control station.

[0026] The introduction of thermal energy into the at least one second sub-section of the component can be carried out in such a way that the temperature decrease of the at least one second sub-section and / or the cooling rate of the at least one second sub-section during step b) and / or while the component remains in the temperature control station is at least reduced. This method is particularly advantageous if the component was heated to a temperature above the AC3 temperature in step a). Alternatively, the introduction of thermal energy into the at least one second sub-section of the component in the temperature control station can be carried out in such a way that the at least one second sub-section of the component is (significantly) heated, in particular by at least approximately 50 K.This procedure is particularly advantageous if the component was heated in step a) to a temperature below the AC3 temperature or even below the AC1 temperature.

[0027] Preferably, the component is moved to a second furnace after step b) and before step c). Particularly preferably, the component is moved from the temperature control station to a second furnace. For this purpose, a transport device, for example, comprising at least a roller table and / or an (industrial) robot, may be provided. Preferably, the component travels a distance of at least 0.5 m from the temperature control station to the second furnace. During this process, the component may be in contact with ambient air or within a protective atmosphere. Preferably, the component is placed directly into the second furnace immediately after being removed from the temperature control station.

[0028] Preferably, after step b) and before step c), at least one first sub-section of the component is heated, particularly in a second furnace, preferably by at least 50 K, more preferably by at least 100 K or even by at least 150 K. Alternatively or additionally, after step b) and before step c), at least one third sub-section of the component can be heated, particularly in a second furnace, preferably by at least 100 K, more preferably by at least 150 K or even by at least 200 K. If the heating of the at least one third sub-section is carried out in addition to the heating of the at least one first sub-section, these heating processes can be carried out simultaneously or at least partially in parallel.

[0029] Particularly preferably, at least one first section or at least one third section of the component is heated in the second furnace (exclusively) by means of radiant heat, for example from at least one electrically operated (non-contacting) heating element, such as a heating loop and / or a heating wire, and / or from at least one (gas-heated) radiant tube. It is further preferably, particularly simultaneously or at least partially in parallel with the heating of the at least one first section and / or the at least one third section, that at least one second section of the component is heated in the second furnace by at least 50 K, particularly preferably by at least 70 K or even by at least 100 K, particularly (exclusively) by means of radiant heat.Particularly preferably, the at least one second sub-section of the component is heated in the second furnace to a temperature above the AC1 temperature or even above the AC3 temperature. Alternatively, particularly simultaneously or at least partially in parallel with the heating of the at least one first sub-section and / or the at least one third sub-section, the temperature decrease of the at least one second sub-section and / or the cooling rate of the at least one second sub-section is at least reduced during the component's time in the second furnace.

[0030] According to the invention, after step b) and before step c), heat energy is introduced into the entire component by means of radiant heat. For example, a second furnace can be provided for this purpose, which can have an interior that is heated (exclusively) by means of radiant heat and in which a (nearly) uniform internal temperature can preferably be set. The introduction of heat energy into the at least one first sub-area of ​​the component in the second furnace preferably takes place such that the temperature of the at least one first sub-area is increased by at least 50 K, preferably by at least 100 K, particularly preferably by at least 150 K or even by at least 200 K.If at least a third sub-area is present, the introduction of heat energy into the at least one third sub-area of ​​the component in the second oven preferably takes place in such a way that the temperature of the at least one third sub-area is increased by at least 100 K, preferably by at least 120 K, particularly preferably by at least 150 K or even by at least 200 K.

[0031] The introduction of heat energy into the at least one second sub-section of the component in the second furnace can preferably be carried out in such a way that the temperature decrease of the at least one second sub-section and / or the cooling rate of the at least one second sub-section during the component's stay in the second furnace is at least reduced. This method is particularly advantageous if the component was heated to a temperature above the AC3 temperature in step a). Alternatively, the introduction of heat energy into the at least one second sub-section of the component in the second furnace can be carried out in such a way that the at least one second sub-section of the component is heated at least (significantly), in particular by at least 50 K, more preferably by at least 70 K or even by at least 100 K; and / or heated to a temperature above the AC1 temperature or even above the AC3 temperature.This procedure is particularly advantageous if the component was heated in step a) to a temperature below the AC3 temperature or even below the AC1 temperature.

[0032] If a second furnace is provided, the component is preferably moved from the second furnace to the press hardening tool before step c). Preferably, this movement from the second furnace to the press hardening tool is carried out by means of a transport device, for example, comprising at least a roller table and / or a handling device, in particular an (industrial)

[0033] Robot. Preferably, the component travels a distance of at least 0.5 m from the second furnace to the press hardening tool. During this process, the component can be in contact with ambient air or within a protective atmosphere. Preferably, the component is transferred directly into the press hardening tool immediately after being removed from the second furnace.

[0034] In step d), purely mechanical post-processing, in particular trimming, of the at least one first sub-section of the component is carried out. Preferably, the mechanical post-processing includes at least separating, cutting, sawing, milling, and / or planing. Particularly preferably, mechanical cutting in and / or on the at least one first sub-section of the component is carried out in step d). Further preferably, mechanical trimming of the component in the area of ​​the at least one first sub-section is carried out in step d). Preferably, the mechanical post-processing includes punching of the at least one first sub-section of the component. Particularly preferably, the post-processing, in particular trimming or punching, is carried out such that a large part, in particular at least 70% or even at least 85%, of the first sub-section of the component is removed and / or separated from the (remaining) component.Furthermore, preferably in step d) a chipless and / or adiabatic separation is carried out, in particular of at least a large part, especially at least 70% or even at least 85%, of the first sub-section of the component (of the (remaining) component). Adiabatic separation can be understood here in particular as a high-speed plastic deformation in the separation zone, which leads in particular to significant heating and thus dissolution or softening of the microstructure. Due to the preferably high speed of the separation process, (virtually) no heat transfer takes place in the material boundary zone (the separation zone).

[0035] In an advantageous embodiment, it is proposed that the mechanical post-processing in step d) be carried out with at least one mechanical cutting tool. Preferably, the mechanical cutting tool has at least two separating elements and / or cutting elements, such as cutting edges or blades, that can be moved (relatively) towards and / or away from each other. More preferably, the cutting tool is a manually operated and / or automatic steel shear. Particularly preferably, the cutting tool is electrically, pneumatically, and / or hydraulically driven.

[0036] In an advantageous embodiment, it is proposed that the component be held in the press hardening tool during mechanical finishing. Preferably, the mechanical finishing is performed while the component is held, clamped, clamped, and / or pressed in the press hardening tool. Preferably, the mechanical finishing is performed immediately after the forming and / or cooling (performed by the press hardening tool). In particular, the mechanical finishing is performed in the press hardening tool.

[0037] In a further advantageous embodiment, it is proposed that the at least one first sub-region of the component forms a flange region and / or a region for a recess. Preferably, at least one first sub-region forms a joining flange of the component. More preferably, the at least one first sub-region forms an edge region of the component. Particularly preferably, the edge region surrounds the entire component.

[0038] Preferably, the at least one first sub-area forms at least a strip extending at least partially along an (outer) contour of the component or along an (outer) component edge. This strip can extend (starting from the (outer) component edge or the (outer) contour) at least 0.005 m [meters], preferably at least 0.01 m or even at least 0.1 m and / or up to 0.3 m, preferably up to 0.2 m or even up to 0.1 m towards the center of the component. The strip can have a (homogeneous or inhomogeneous) width of preferably 0.05 m to 0.15 m, particularly preferably approximately 0.1 m, transversely to its direction of extension along the (outer) contour or along the (outer) component edge. Preferably, the strip is formed along the entire (outer) contour of the component or along the entire (outer) component edge.This allows the component to be manufactured with a more ductile component edge, which enables easier trimming of the (outer) contour of the component.

[0039] Another aspect is the proposal for a device for the heat treatment of a steel component, which includes at least the following: a heatable first furnace, at least one temperature control station designed and equipped to set a temperature difference between at least one first sub-area and at least one second sub-area of ​​the component, a second furnace with a furnace interior heated by means of radiant heat, wherein the second furnace is designed to introduce heat energy into the entire steel component, at least one press hardening tool, at least one mechanical finishing device associated with the press hardening tool.

[0040] Preferably, the first furnace can be heated by radiant heat and / or convection. The second furnace can be heated by radiant heat. It is particularly preferred that the second furnace is located downstream of the temperature control station. Furthermore, it is preferred that the second furnace is designed and configured to heat at least one first section or at least one third section of the component by at least 50 K, preferably by at least 100 K, particularly preferably by at least 150 K, or even by at least 200 K.

[0041] In a further advantageous embodiment, it is proposed that at least the first or the second furnace be a continuous furnace or a chamber furnace. Preferably, the first furnace is a continuous furnace, in particular a roller hearth furnace. Particularly preferably, the second furnace is a continuous furnace, in particular a roller hearth furnace, or a chamber furnace, in particular a multi-layer chamber furnace with at least two chambers arranged one above the other.

[0042] Preferably, the second furnace has an interior that can be heated (exclusively) by means of radiant heat, in which a (nearly) uniform internal temperature can preferably be set. Particularly if the second furnace is designed as a multi-layer chamber furnace, several such interiors can be present, corresponding to the number of chambers.

[0043] Preferably, radiant heat sources are arranged in the first furnace and / or the second furnace (exclusively). Particularly preferably, at least one electrically operated heating element (not in contact with the component), such as at least one electrically operated heating loop and / or at least one electrically operated heating wire, is arranged in an interior compartment of the first furnace and / or in an interior compartment of the second furnace. Alternatively or additionally, at least one radiant tube, particularly gas-heated, can be arranged in the interior compartment of the first furnace and / or the interior compartment of the second furnace. Preferably, several radiant tube gas burners or radiant tubes are arranged in the interior compartment of the first furnace and / or the interior compartment of the second furnace, each with at least one gas burner operating within it.It is particularly advantageous if the inner area of ​​the steel tubes, into which the gas burners fire, is atmospherically separated from the furnace interior, so that no combustion gases or exhaust gases can enter the furnace interior and thus affect the furnace atmosphere. Such an arrangement is also known as "indirect gas heating".

[0044] Preferably, the temperature control station is located downstream of the first furnace. At least one nozzle can be arranged or held in the temperature control station, which is designed and configured to discharge a fluid. Preferably, the at least one nozzle is designed and configured to discharge a fluid for cooling the at least one first sub-section and / or at least one third sub-section of the component. This makes it particularly advantageous to adjust the temperature difference between the at least one first sub-section or the at least one third sub-section and at least one second sub-section of the component. It is especially preferred that the at least one nozzle is oriented such that it can discharge the fluid towards the first sub-section and / or a third sub-section of the component.Preferably, a nozzle array with multiple nozzles is arranged in the temperature control station, with each nozzle being designed and configured to discharge a fluid. Particularly preferred is the shape of the nozzle array and / or the arrangement of the multiple nozzles adapted to the (to be achieved) geometry of the at least one first sub-area and / or the at least one third sub-area of ​​the component.

[0045] Preferably, at least one heating device is arranged in the temperature control station. Preferably, the heating device is designed and configured to introduce heat energy into at least one second sub-section of the component. Particularly preferably, the heating device is arranged and / or oriented in the temperature control station such that the introduction of heat energy into at least one second sub-section of the component can be carried out simultaneously or at least partially in parallel with the cooling of at least one first sub-section and / or at least one third sub-section of the component by means of the at least one nozzle. Preferably, the heating device comprises (exclusively) at least one radiant heat source.Particularly preferred is the at least one radiant heat source comprising at least one electrically operated heating element (which does not contact the component mechanically and / or electrically), such as at least one electrically operated heating loop and / or at least one electrically operated heating wire. Alternatively or additionally, at least one gas-heated radiant tube can be provided as the radiant heat source.

[0046] Preferably, the press hardening tool is arranged downstream of a second furnace. The press hardening tool is specifically designed and configured to simultaneously or at least partially deform and (at least partially) cool the component, particularly by quenching it.

[0047] The at least one mechanical post-processing device is associated with the press hardening tool. Preferably, the post-processing device can be arranged, or is arranged, in the area of ​​the press hardening tool. Particularly preferably, the post-processing device can be aligned, or is aligned, towards the press hardening tool. Furthermore, preferably, the post-processing device is connected to the press hardening tool, in particular electronically, mechanically, pneumatically, hydraulically, and / or via a signal system, such that the post-processing device interacts with the press hardening tool. The post-processing device can be a separate device (from the press hardening tool) or at least partially integrated into the press hardening tool and / or rigidly connected to it.The post-processing device can (for this purpose) include, for example, a post-processing tool, in particular a separating tool, punching tool and / or cutting tool, which is preferably integrally formed or integrated into the press hardening tool, in particular into an upper shell and / or a lower shell of the press hardening tool, or which is rigidly connected to the press hardening tool. Thus, a first part of a post-processing tool, in particular a first cutting edge, can be connected to an upper shell of the press hardening tool and / or a second part of a post-processing tool, in particular a second cutting edge, can be connected (directly and / or rigidly) to a lower shell of the press hardening tool.

[0048] According to an advantageous embodiment, it is proposed that the at least one mechanical post-processing device comprises at least one mechanical cutting tool.

[0049] Preferably, the device serves to carry out a method proposed herein. According to an advantageous embodiment, it is proposed that the device is designed and configured to carry out a method proposed herein.

[0050] The details, features, and advantageous embodiments discussed in connection with the method may also occur in the device presented here, and vice versa. In this respect, full reference is made to the explanations given therein for a more detailed characterization of the features.

[0051] The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not limited to the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations explained in the figures and combine them with other components and / or findings from other figures and / or the present description. The figures schematically show: Fig. 1: a diagram of a device for the heat treatment of a metallic component, and Fig. 2: a top view of a metallic component.

[0052] Fig. 1Figure 8 schematically shows a diagram of a device 8 for the heat treatment of a metallic component 1. The device 8 comprises a first furnace 9, a tempering station 10, and a press hardening tool 4. For illustrative purposes, a second furnace 12 is provided between the tempering station 10 and the press hardening tool 4. Here, the device 8 represents a hot forming line for press hardening. The tempering station 10 is directly downstream of the first furnace 9, so that a component 1 to be treated by the device 8 can be transferred directly into the tempering station 10 after leaving the first furnace 9. Furthermore, the second furnace 12 is directly downstream of the tempering station 10, and the press hardening tool 4 is directly downstream of the second furnace 12.

[0053] Furthermore, the in Fig. 1The illustrated device includes a mechanical post-processing unit 11, which is associated with the press hardening tool 4. The mechanical post-processing unit 11 has a cutting tool 5 with which the metallic component 1 can be at least partially trimmed.

[0054] Fig. 2Figure 1 schematically shows a top view of a metallic component 1 with two first sub-sections 2 and two second sub-sections 3. According to the invention, the component is made of steel. Furthermore, the component has, by way of example, a third sub-section 13. The component 1 is shown here in a state after press hardening. In the second sub-sections 3, the component 1 is (fully martensitic) hardened. Thus, the component 1 exhibits high strength in the second sub-sections 3. In contrast, the component 1 exhibits lower strength in the first sub-sections. However, the component 1 exhibits its lowest strength in the third sub-section 13. The third sub-section 13 can, for example, serve to absorb impact energy acting on the component 1.

[0055] According to the presentation Fig. 2One of the first sub-areas 2 of component 1 forms a flange area 6, and another of the first sub-areas 2 forms an area for a recess 7. Since the first sub-areas 2 have reduced strength compared to the (fully martensitic) hardened second sub-areas 3, the flange area 6 and the area for the recess 7 can be easily machined. Fig. 2 Flange area 6 has not yet been mechanically machined. However, the area for recess 7 has already been mechanically machined, so that recess 7 is in Fig. 2 is recognizable.

[0056] A method and a device for the heat treatment of a steel component are described, which at least partially solve the problems outlined with reference to the prior art. In particular, the method and the device enable the production of a press-hardened component with highly precise contours in industrial series production. Furthermore, the method and the device can be implemented and operated with minimal energy consumption and / or with minimal investment costs. In addition, the method and the device allow for the shortest possible cycle time. Reference symbol list

[0057] 1 Component 2 First section 3 Second section 4 Press hardening tool 5 Cutting tool 6 Flange section 7 Recess 8 Fixture 9 First furnace 10 Tempering station 11 Post-processing equipment 12 Second furnace 13 Third section

Claims

1. Method for thermally treating a steel component (1) comprising at least the following steps, carried out in the stated order: a) heating the component (1), b) setting a temperature difference of at least 50 K between at least one first partial region (2) and at least one second partial region (3) of the component (1), b') feeding heat energy into the entire component (1) by means of radiant heat, c) at least partially forming and / or cooling the component (1) in a press hardening tool (4), d) mechanically reworking the at least one first partial region (2) of the component (1), wherein the setting of the temperature difference in step b) is carried out by cooling the at least one first partial region (2) and / or heating the at least one second partial region (3), and wherein the at least one first partial region (2) that is to be reworked is provided with a lower strength than the at least one second partial region (3) before step d) and at the time of the mechanical reworking.

2. Method according to Claim 1, wherein the component is heated by at least 500 K by means of radiant heat and / or convection in step a).

3. Method according to either of the preceding claims, wherein the mechanical reworking in step d) is carried out with at least one mechanical cutting tool (5).

4. Method according to one of the preceding claims, wherein the component (1) is kept in the press hardening tool (4) during the mechanical reworking.

5. Method according to one of the preceding claims, wherein the at least one first partial region (2) of the component (1) forms a flange region (6) and / or a region for a cutout (7).

6. Apparatus (8) for thermally treating a steel component (1), at least comprising: - a heatable first furnace (9), - at least one temperature control station (10), which is designed and configured to set a temperature difference between at least one first partial region (2) and at least one second partial region (3) of the component (1), - a second furnace (12) which has a furnace interior heatable by means of radiant heat, wherein the second furnace (12) is configured to feed heat energy into the entire steel component (1), - at least one press hardening tool (4), - at least one mechanical reworking device (11) assigned to the press hardening tool (4).

7. Apparatus according to Claim 6, wherein the at least one mechanical reworking device (11) has at least one mechanical cutting tool (5).

8. Apparatus according to Claim 6 or 7, wherein the apparatus (8) is designed and configured to carry out a method according to one of Claims 1 to 6.