Thermal treatment of a coated component

Abstract

The invention relates to a method for thermally treating a coated component (2), having the steps of: a) thermally treating the component (2) in a first continuous furnace (3) that is divided into a first zone (6) and a second zone (7), which adjoins the first zone and through which the component (2) passes afterwards, in the transport direction (r) of the component (2), wherein the component (2) is heated to a first temperature (T1) lying above the ACS temperature (TAC3) of the component (2) in the first zone (6) and is cooled to a second temperature (T2) lying below the AC3 temperature (TACS) of the component (2) in the second zone (7), b) transferring the component (2) from the first continuous furnace (3) into a temperature control station (4), and c) thermally treating the component (2) in the temperature control station (4). A first region of the component (2) is exposed to a temperature which on average lies above the AC3 temperature (TAC3) of the component (2), and a second region of the component (2) is cooled. By virtue of the aforementioned thermal treatment which varies from section to section, the coated component (2) obtains a ductility which varies from section to section, said ductility being advantageous in B pillars for motor vehicles for example. By heating the component to a temperature above AC3 and then cooling the component to a temperature below AC3 in the first continuous furnace (3), a particularly readily adjustable thickness of the interdiffusion layer of the coating of the component (2) is achieved.

Description

[0001] The invention relates to a method and a device for the thermal treatment of a coated component, in particular a steel component for a motor vehicle.

[0002] In the automotive industry in particular, it is well known to specifically harden steel components through thermal treatment. For this purpose, steel components such as B-pillars are thermally treated differently in certain areas. This results in different ductility in certain areas, which is advantageous for the crash behavior of such components. For example, occupants can be protected by a hard section of the B-pillar at seat height, while soft sections in the upper and lower sections of the B-pillar absorb energy through deformation.

[0003] Furthermore, it is known to coat steel components to prevent scaling during thermal treatment. It is desirable to achieve a particularly strong bond between the surface of the component to be coated and the coating. Methods for thermally treating components are known, for example, from EP 3 530 760 A1, EP 3 211 103 A1, DE 10 2016 202 766 A1, WO 2019 / 011 650 A1, and DE 10 2013 107 870 A1.

[0004] The object of the present invention is to provide, based on the described prior art, a method for thermally treating a coated component that bonds the coating particularly firmly to the surface to be coated. Furthermore, a corresponding device is to be presented.

[0005] These objects are achieved by the method and device according to the independent claims. Further advantageous embodiments are specified in the dependent claims. The features presented in the claims and in the description can be combined with one another in any technologically expedient manner.

[0006] According to the invention, a method for thermally treating a coated component is presented. The method comprises: a) thermally treating the component in a first continuous furnace, which is divided in the transport direction of the component into a first zone and a second zone adjoining the first zone and through which the component later passes, wherein the component is heated in the first zone to a first temperature which is above the AC3 temperature of the component and cooled in the second zone to a second temperature which is below the AC3 temperature of the component, b) transferring the component from the first continuous furnace to a tempering station, c) thermally treating the component in the tempering station, wherein a first region of the component is exposed to a temperature which is on average above the AC3 temperature of the component, and a second region of the component is cooled.

[0007] A coated component can be thermally treated using the described method. The component is preferably a steel component. The steel is preferably a heat-treatable steel, in particular 22MnB5. For example, a component for a motor vehicle, in particular a B-pillar, can be thermally treated using the described method. After the thermal treatment, the component is preferably press-hardened in a press and thus hot-formed. The method preferably comprises, as a further step, transferring the component to a press after the thermal treatment and press-hardening there. In this case, the described method is a method for the thermal treatment and press-hardening of a component. The component is preferably coated with Al / Si. Such a coating counteracts scaling of the component surface during the thermal treatment particularly effectively.The coating thickness is preferably in the range of 10 to 50 µm. A hardenable carbon steel with an Al-Si coating is preferred as the component material.

[0008] In step a), the component is thermally treated in the first continuous furnace. After passing through the first continuous furnace, the component's temperature is higher than before. Therefore, the component is heated in the first continuous furnace. This does not preclude the component's temperature from falling from an initially reached maximum value and cooling down in the first continuous furnace.

[0009] A furnace is a device whose interior is heated to an adjustable temperature and into which a component can be inserted. Over time, the component adopts the temperature prevailing inside the furnace. The heat is thus transferred from the gas in the furnace, which can particularly be air, to the component. A continuous furnace is a furnace through which the component can be moved, with the component being heated as it passes through the furnace. The residence time in the first continuous furnace is preferably in the range of 200 to 450 seconds.

[0010] The first continuous furnace is preferably a roller hearth furnace. The first continuous furnace is preferably gas-heated and / or electrically heated. This allows the component to achieve a particularly evenly distributed temperature. In particular, not just a layer on the surface of the component is heated. The entire component is heated in the first continuous furnace. The component is completely absorbed by the first continuous furnace. Furthermore, a continuous furnace can achieve heating by a particularly large temperature difference. With a continuous furnace, the component can be heated, in particular, from room temperature to a temperature above the AC3 temperature of the component.

[0011] Heating in a continuous furnace is particularly in contrast to heating by so-called "direct energization." This would make it difficult to heat the component evenly and to a sufficiently high degree. With direct energization, the speed of heating is more important. Furthermore, direct energization requires contact with the component. In step a) of the described process, heating is preferably carried out contactless. This does not preclude the component from being moved through the first continuous furnace on conveyor rollers and thus being in contact with the conveyor rollers. Heating is contactless if the heat is introduced into the component via a gas and / or thermal radiation.

[0012] The first continuous furnace and the rest of the equipment used for the process are described using a "transport direction of the component." This is the direction in which the component is moved through the equipment and its elements. The transport direction of the component is therefore, in particular, the direction in which the component is moved through the first continuous furnace.

[0013] When viewed along the transport direction defined in this way, the first continuous furnace has a first zone and a second zone. The fact that the first continuous furnace is "divided" into these two zones in the transport direction of the component means that the first continuous furnace only has these two zones when viewed along the transport direction of the component. Perpendicular to the transport direction of the component, the zones preferably extend across the entire first continuous furnace.

[0014] The component first passes through the first zone and then the second zone. Viewed in the direction of transport, the second zone is located downstream of the first zone. The first zone and the second zone are directly adjacent to one another. The first zone is adjacent to an inlet of the first continuous furnace, while the second zone is adjacent to an outlet of the first continuous furnace. The component can be introduced into the first continuous furnace via the inlet. The component can exit the first continuous furnace via the outlet.

[0015] In the first zone, the component is heated to a first temperature above the component's AC3 temperature. At least in part of the first zone, a temperature above the component's AC3 temperature is set. Heating to the first temperature results in diffusion exchange between the coating materials and the rest of the component. A so-called interdiffusion layer forms, in which the coating materials and the rest of the component are mixed together at the atomic level. Tests have shown that the described temperature control allows the desired thickness of the interdiffusion layer to be preset with particular precision.

[0016] For the subsequent process steps, especially for step c), it is advantageous if the component leaves the first continuous furnace at a temperature below the component's AC3 temperature. This way, if the AC3 temperature is exceeded, austenite forms. In areas of the component that are intended to achieve higher ductility, the resulting austenite should be removed as quickly as possible. Therefore, the temperature of the first continuous furnace in the second zone is set so that the component cools to a second temperature that is below the component's AC3 temperature.

[0017] The temperature of the component is influenced by the set temperature profile of the first continuous furnace. In the simplest case, the temperature in the first zone is set to the first temperature and in the second zone to the second temperature. If the component is moved sufficiently slowly through the first continuous furnace, the component temperature will reach the first temperature at the end of the first zone and the second temperature at the end of the second zone. A suitable transport speed depends in particular on the material thickness and the material of the component and can be easily determined through tests or simulations.

[0018] It should be noted that short-term and / or locally limited temperature changes within the first continuous furnace have almost no relevance for the heating of the component. This is because the temperature of the component adapts comparatively slowly to the temperature in the first continuous furnace. To take this fact into account, it is preferable that the average temperature in the first zone is above the AC3 temperature of the component and / or that the average temperature in the second zone is below the AC3 temperature of the component. The average temperature is understood to be the average temperature to which the component is exposed in the respective zone. This is the temperature in a component plane of the first continuous furnace, i.e. the plane in which the component is transported through the first continuous furnace.In particular, in the case of a gas-fired first continuous furnace, locally elevated temperatures in the area of ​​the burners should be disregarded if these are spaced apart from the component.

[0019] It is sufficient that the zones are only differentiated from one another by the temperature established in the component. This temperature can be determined, for example, by a drag measurement. Furthermore, it is not necessary for the zones to be distinct or for boundaries between the zones to be recognizable as such. Furthermore, it is possible for a first zone and a second zone to be defined in the first continuous furnace in different ways. It is sufficient if there is a possible assignment of a first zone and a possible assignment of a second zone, whereby all conditions specified for both zones are met. Alternative assignment options are then irrelevant. Nevertheless, the assignment of the zones should preferably not be arbitrary.If the temperature profile along the transport direction of the component exhibits clearly identifiable jumps, the boundary between the zones preferably coincides with such a clearly identifiable jump. Thus, it is particularly preferred that the temperature set in the first continuous furnace at the boundary between the first zone and the second zone be at the AC3 temperature of the component. This is particularly the case if the boundary between the two zones lies at a jump in the temperature set in the first continuous furnace from a value above the AC3 temperature of the component to a value below the AC3 temperature of the component.

[0020] Furthermore, it is preferred that the temperature set in the first continuous furnace is above the AC3 temperature of the component over at least 50% of the extent of the first zone in the transport direction of the component. Likewise, it is preferred that the temperature set in the first continuous furnace is below the AC3 temperature of the component over at least 80% of the extent of the second zone in the transport direction of the component. Particularly preferably, the temperature in the entire first zone is above the AC3 temperature. Particularly preferably, the temperature in the entire second zone is below the AC3 temperature. These statements also refer to the temperature to which the component is exposed in the first continuous furnace.

[0021] The first continuous furnace preferably has a plurality of heating elements, the temperature of which can preferably be individually adjusted. The first zone and the second zone preferably correspond to a respective group of heating elements. The allocation of the heating elements to a zone can be carried out by a control device and therefore does not have to be recognizable on the heating elements themselves. The only decisive factor is the temperature distribution. By changing the temperature setting of a heating element at the boundary between the first zone and the second zone, the allocation of this heating element can be changed from the first zone to the second zone, and vice versa. In general, the extent of the zones can be changed by changing the allocation of heating elements at the boundary between the zones. The temperature distribution of the zone can be adjusted by the respective temperature setting of the heating elements.All heating elements in a zone are preferably set to the same temperature.

[0022] In step b) of the process, the component is transferred from the first continuous furnace to the tempering station. There, in step c), the component is thermally treated differently in certain areas by exposing a first area of ​​the component to a temperature that is, on average, above the AC3 temperature of the component, and cooling a second area of ​​the component.

[0023] The first continuous furnace and the tempering station are separate components that are spatially separated from each other. The transfer between the first continuous furnace and the tempering station facilitates the cooling of the component between heating in the first continuous furnace and thermal treatment in the tempering station. In the tempering station, the component is cooled as quickly as possible in certain areas. Rapid cooling can be achieved more efficiently outside the hot first continuous furnace. This allows cooling to begin during the transfer. In this respect, the spatial separation of the first continuous furnace from the tempering station accelerates the process. This contrasts with a solution in which all process steps are carried out in the same facility without having to transfer the component. Such solutions typically aim to minimize the effort required for component transfers or to avoid them altogether.The spatial separation between the first continuous furnace and the tempering station also simplifies the design, because the requirements for the first continuous furnace and the tempering station are different. Integrating both into one facility would therefore be correspondingly complicated.

[0024] In the temperature control station, the first region is exposed to a temperature above the AC3 temperature of the component, in particular 170 to 250 K above the AC3 temperature of the component, and is heated to this extent. The first region of the component is preferably exposed to a temperature above the AC3 temperature of the component to the extent that the component is held with the first region against a chamber that is open on the component side, wherein the chamber is maintained at this temperature by a heating device. The heating device is preferably an electric heating device. The heating device can, for example, have a heating element such as a heating loop. Alternatively or additionally, the heating device can comprise a jet pipe that is heated by a burner, in particular a gas burner.

[0025] The second area is cooled in the temperature control station. This is preferably achieved by keeping the second area outside the previously described chamber. There, the second area is preferably exposed to a cooling fluid, in particular compressed air. The compressed air preferably has a pressure in the range of 2 to 4.5 bar. This comparatively high pressure allows a large amount of compressed air to be directed to the second area of ​​the component within a very short time, thus achieving a sufficiently high cooling rate.

[0026] Cooling of the second zone in step c) preferably begins with a delay of 0.5 to 15 seconds after the completion of step b). Cooling does not begin immediately after the component enters the temperature control station. This allows cooling through free radiation to the environment to be used for cooling, which can, for example, save cooling fluid. The cooling that begins after the delay is active cooling. This allows the strength properties of the component to be adjusted particularly precisely.

[0027] Whether and to what extent the temperature of the component is above or below the AC3 temperature of the component significantly influences the resulting microstructure. By thermally treating the different areas of the component differently, the two areas can acquire different microstructures and, thus, different ductilities. The first area thus becomes harder than the second area. For example, the crash properties of a B-pillar for a motor vehicle can be specifically adjusted.

[0028] The first region and the second region are not necessarily contiguous regions. In particular, it is possible for a central part of a B-pillar to represent the first region, while an upper and a lower part of the B-pillar together represent the second region. The component preferably, but not necessarily, has only the first region and the second region, i.e., no further regions.

[0029] According to the invention, the method further comprises: d) Transferring the component from the tempering station to a second continuous furnace, e) Thermally treating the component in the second continuous furnace. The tempering station and the second continuous furnace are separate components that are spatially separated from each other. The transfer between the tempering station and the second continuous furnace facilitates the cooling of the component between the thermal treatment in the tempering station and in the second continuous furnace. This allows the second area of ​​the component to be cooled even during the transfer. This reduces the required size of the tempering station and accelerates the process. This contrasts with a solution in which all process steps are carried out in the same facility, if possible, without having to transfer the component. Such solutions typically aim to minimize the effort required for component transfers or to eliminate them altogether.

[0030] The second continuous furnace is preferably a roller hearth furnace. The entire component is thermally treated in the second continuous furnace. The component is completely absorbed by the second continuous furnace. Thermal treatment in a continuous furnace contrasts particularly with heating by so-called "direct energization."

[0031] It has been found that, particularly in this embodiment, the described advantage is achieved: the zones with different temperatures in the first continuous furnace allow a particularly well-adjustable interdiffusion layer thickness to be achieved. This advantage is achieved in a special way by combining steps a) to e).

[0032] In a further preferred embodiment of the method, the first temperature is in the range of 10 to 30 K above the AC3 temperature of the component and / or the second temperature is in the range of 80 to 150 K below the AC3 temperature of the component.

[0033] The preferred combination is that the first temperature is in the range of 10 to 30 K above the AC3 temperature of the component and that the second temperature is in the range of 80 to 150 K below the AC3 temperature of the component.

[0034] Tests have shown that the described advantages can be achieved, particularly with the specified temperature values.

[0035] In the case of 22MnB5, it is preferred that the first temperature is 856 to 876°C and the second temperature is 696 to 766°C.

[0036] In a further preferred embodiment of the method, the component in step a) is held at a temperature within 10 K of the first temperature for 30 to 100 s, in particular for 50 to 80 s, before leaving the first zone of the first continuous furnace and / or the component in step a) is held at a temperature within 10 K of the second temperature for 20 to 60 s, in particular for 35 to 45 s, before leaving the first continuous furnace.

[0037] The combination is preferred that the component in step a) is held at a temperature within 10 K of the first temperature for 30 to 100 s, in particular for 50 to 80 s, before leaving the first zone of the first continuous furnace and that the component in step a) is held at a temperature within 10 K of the second temperature for 20 to 60 s, in particular for 35 to 45 s, before leaving the first continuous furnace.

[0038] Preferably, in step a), the component is held at the first temperature for 30 to 100 seconds, in particular for 50 to 80 seconds, before leaving the first zone of the first continuous furnace, and at the second temperature for 20 to 60 seconds, in particular for 35 to 45 seconds, before leaving the first continuous furnace. However, since minor temperature fluctuations are not important, holding it at a temperature that differs by no more than 10 K from the first temperature or from the second temperature is sufficient.

[0039] Holding the material at the first temperature allows sufficient time for the interdiffusion layer to form. Holding the material at the second temperature allows the previously formed austenite to be sufficiently broken down without the temperature dropping more than is beneficial for the subsequent process steps.

[0040] In a further preferred embodiment of the method, the first zone extends in the transport direction of the component over 30 to 80% of the first continuous furnace.

[0041] The first zone is designed to be long enough for the component to exceed the AC3 temperature in it and preferably to be held at this temperature for the holding time specified above. The second zone is designed to be long enough for the component to cool to the second temperature in the second zone and to be held at this temperature for the holding time specified above. The longer the first zone, the shorter the second zone. It has been found that the interdiffusion layer is particularly well adjustable in this embodiment.

[0042] Particularly preferably, the first zone extends over 50 to 70% of the first continuous furnace in the transport direction of the component.

[0043] In a further preferred embodiment of the method, an average temperature in a half of the first zone through which the component first passes is at least 20 K higher than in the remaining first zone.

[0044] In this embodiment, the temperature set in the first zone is not constant, but on average higher in the first half of the first zone than in the second half of the first zone. Due to the higher temperature, the component is heated comparatively quickly at the beginning of the first zone. Rapid heating is advantageous in the first zone because the first zone can then be shorter and a correspondingly larger part of the first continuous furnace remains for the second zone. However, the first component in the first zone should only be heated to the first temperature. Therefore, the temperature of the first continuous furnace is selected to be lower in the second half of the first zone. At the end of the first zone, the temperature is preferably set to the first temperature.

[0045] As a further aspect of the invention, a device for thermally treating a coated component is presented. The device comprises: a first continuous furnace which is divided in the transport direction of the component into a first zone and a second zone arranged downstream of the first continuous furnace in the transport direction of the component, wherein the temperature control station is designed to expose a first region of the component to a temperature which is on average above the AC3 temperature of the component and to cool a second region of the component, a control device which is designed to set a temperature distribution in the first continuous furnace such that the component heats up in the first zone to a first temperature which is above the AC3 temperature of the component and cools down in the second zone to a second temperature which is below the AC3 temperature of the component.

[0046] The described particular advantages and design features of the method are applicable and transferable to the device, and vice versa. The device is preferably designed and configured for operation according to the method. The method is preferably carried out using the device. According to the invention, the device comprises a second continuous furnace, which is arranged downstream of the tempering station in the transport direction of the component.

[0047] The fact that the second zone of the first continuous furnace is located downstream of the first zone in the component's transport direction means that the component passes through the second zone later than the first zone. The same applies to the tempering station and the second continuous furnace, which are located downstream of the first continuous furnace and the tempering station, respectively, in the component's transport direction.

[0048] The invention is explained in more detail below with reference to the figures. The figures show a particularly preferred embodiment, to which the invention is not limited, however. The figures and the proportions depicted therein are merely schematic. They show: Fig. 1: a device according to the invention for the thermal treatment of a component, Fig. 2: a temperature profile which can be obtained with the device from Fig. 1 when carrying out a method according to the invention for thermally treating the component.

[0049] Fig. 1 shows a device 1 for thermally treating a coated component 2. The device 1 comprises a first continuous furnace 3, which has a first zone 6 in the transport direction r of the component 2 and a second zone 7 arranged downstream of the first zone 6. The second zone 7 is therefore passed through later by the component 2 and is therefore located in Fig. 1to the right of the first zone 6. The first continuous furnace 3 is divided into the first zone 6 and the second zone 7 in the transport direction r, thus having no further zones in this direction. The first zone 6 extends in the transport direction r of the component 2 over 30 to 80% of the first continuous furnace 3. The first zone 6 and the second zone 7 extend transversely to the transport direction r - thus in Fig. 1 up and down as well as perpendicular to the plane of the drawing - over the entire first continuous furnace 3.

[0050] The device 1 further comprises a tempering station 4 arranged downstream of the first continuous furnace 3 in the transport direction r of the component 2. The device 1 further comprises a second continuous furnace 5 which is arranged downstream of the tempering station 4 in the transport direction r of the component 2. The temperatures in the first zone 6 of the first continuous furnace 3, in the second zone 7 of the first continuous furnace 3, in the tempering station 4 and in the second continuous furnace 5 can be adjusted via a control device 8. This is indicated by dotted lines. The control device 8 is designed in particular to set a temperature distribution in the first continuous furnace 3 such that the component 2 heats up in the first zone 6 to a first temperature T 1 which is above the AC3 temperature T AC3 of the component 2 and cools down in the second zone 7 to a second temperature T 2 which is below the AC3 temperature T AC3 of the component 2.

[0051] Fig. 2 shows a temperature profile that occurs in the component 2 when it is heated by the device 1 from Fig. 1 The representation of Fig. 2is schematic. Shown is a plot of temperature T over time t in arbitrary units. The component 2 is first heated in the first continuous furnace 3. The residence time of the component 2 in the first continuous furnace 3 is designated by t D1 and divided into the residence time in the first zone 6, designated by t Z1, and the residence time in the second zone 7, designated by t Z2. In the first zone 6, the temperature of the first continuous furnace 3 is set such that the component 2 in the first zone 6 heats up to the first temperature T1. At the end of the first zone 6, the component 2 is held at the first temperature T1 for a first holding time t H1. In the second zone 7, the temperature of the first continuous furnace 3 is set such that the component 2 cools down to the second temperature T2 in the second zone 7. At the end of the second zone 7, the component is held at the second temperature T2 for a second holding time t H2.

[0052] In a further preferred embodiment, T 2 is chosen so low that component 2 does not reach temperature T 2 within the specified time, but remains below the temperature required for the decomposition of the austenite long enough. In this case, no approximately isothermal holding at T 2 occurs.

[0053] The component 2 is then transferred to the temperature control station 4. The associated transfer time is designated t T1 . During this transfer, the component 2 cools down. The component 2 remains in the temperature control station 4 for a residence time t TS . During this time, the component 2 is thermally treated in the temperature control station 4 by exposing a first area of ​​the component 2 to a temperature that is constantly above the AC3 temperature T AC3 of the component 2, and by cooling a second area of ​​the component 2. The temperature of the first area is designated TA, the temperature of the second area by TB .

[0054] After thermal treatment of component 2 in the tempering station 4, the component 2 is transferred to the second continuous furnace 5. The transfer time for this is designated t T2 . During this time, component 2 also cools down, which can vary depending on the material thickness and the transfer time t T2 .

[0055] In the second continuous furnace 5, component 2 is further thermally treated by heating it overall. For this purpose, component 2 is preferably exposed to a temperature that is above the AC3 temperature T AC3 of component 2. Due to the greater temperature difference, the colder second region of component 2 is heated more quickly than the warmer first region. The residence time of component 2 in the second continuous furnace 5 is designated T D2 .

[0056] Due to the thermal treatment, which varies from region to region, the coated component 2 acquires different ductility. This is advantageous, for example, for a B-pillar of a motor vehicle. Heating to above AC3 and subsequent cooling to below AC3 in the first continuous furnace 3 achieves a particularly well-adjustable thickness of the interdiffusion layer of the coating on component 2. List of reference symbols

[0057] 1Device 2Component 3First continuous furnace 4Temperature control station 5Second continuous furnace 6First zone 7Second zone 8Control device TTemperature T AC3 AC3 temperature of the component T 1 first temperature T 2 second temperature TA temperature of the first area of ​​the component TB temperature of the second area of ​​the component tTime t D1 ,Residence time in the first continuous furnace t Z1 Residence time in the first zone of the first continuous furnace t H1 First holding time t Z2 Residence time in the second zone of the first continuous furnace t H2 Second holding time t T1 Transfer time from the first continuous furnace to the tempering station t TS Residence time in the tempering station t T2 Transfer time from the tempering station to the second continuous furnace t D2 Residence time in the second continuous furnace rTransport direction of the component

Claims

1. Method for thermally treating a coated component (2), comprising: a) thermally treating the component (2) in a first continuous furnace (3) subdivided, in the transport direction (r) of the component (2), into a first zone (6) and a second zone (7) following the first zone and passed through by the component (2) later, wherein the component (2) is heated in the first zone (6) to a first temperature (T1) above the AC3 temperature (TAC3) of the component (2) and is cooled in the second zone (7) to a second temperature (T2) below the AC3 temperature (TAC3) of the component (2), b) transferring the component (2) from the first continuous furnace (3) to a temperature-control station (4), c) thermally treating the component (2) in the temperature-control station (4), wherein a first region of the component (2) is subjected to a temperature on average above the AC3 temperature (TAC3) of the component (2), and a second region of the component (2) is cooled, d) transferring the component (2) from the temperature-control station (4) to a second continuous furnace (5), e) thermally treating the component (2) in the second continuous furnace (5).

2. Method according to Claim 1, wherein the first temperature (T1) ranges from 10 to 30 K above the AC3 temperature (TAC3) of the component (2) and / or wherein the second temperature (T2) ranges from 80 to 150 K below the AC3 temperature (TAC3) of the component (2).

3. Method according to either of the preceding claims, wherein in step a), before leaving the first zone (6) of the first continuous furnace (3), the component (2) is held at a temperature within 10 K around the first temperature (T1) for 30 to 100 s and / or wherein in step a), before leaving the first continuous furnace (3), the component (2) is held at a temperature within 10 K around the second temperature (T2) for 20 to 60 s.

4. Method according to one of the preceding claims, wherein the first zone (6) extends over 30 to 80% of the first continuous furnace (3) in the transport direction (r) of the component (2).

5. Method according to one of the preceding claims, wherein an average temperature in a half of the first zone (6) that the component (2) passes through first is at least 20 K higher than in the rest of the first zone (6).

6. Apparatus (1) for thermally treating a coated component (2), comprising: - a first continuous furnace (3) subdivided, in the transport direction (r) of the component (2), into a first zone (6) and a second zone (7) downstream of the first zone, - a temperature-control station (4) downstream of the first continuous furnace (3) in the transport direction (r) of the component (2), the temperature-control station (4) being designed to subject a first region of the component (2) to a temperature on average above the AC3 temperature (TAC3) of the component (2), and to cool a second region of the component (2), - a second continuous furnace (5) downstream of the temperature-control station (4) in the transport direction (r) of the component (2), - a control device (8) designed to set such a temperature distribution in the first continuous furnace (3) that the component (2) is heated in the first zone (6) to a first temperature (T1) above the AC3 temperature (TAC3) of the component (2) and is cooled in the second zone (7) to a second temperature (T2) below the AC3 temperature (TAC3) of the component (2).

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