EP2554288A1 - Procédé et outil de traitement thermique d'une matière première en tôle d'aluminium ainsi que la matière première en tôle d'aluminium traitée par ce type de procédé - Google Patents

Abstract

Heat treating of aluminum sheet material (8), comprises: providing aluminum sheet material; heating the aluminum sheet material at a temperature that is >= heating temperature; maintaining the temperature during a heating period; quenching a deterrent portion (10) of the sheet material at a temperature = a quenching temperature; and cooling a cooling portion (11) of the sheet material at a temperature = a cooling temperature, where cooling takes place within a cooling period, which is greater than the quenching period, and shielding of the cooling portion by a tool occurs during quenching. Heat treating of aluminum sheet material (8), comprises (a) providing aluminum sheet material, (b) heating the aluminum sheet material at a temperature that is >= heating temperature, (c) maintaining the temperature during heating period, (d) quenching at least one deterrent portion (10) of the aluminum sheet material at a temperature that is = a quenching temperature, where the quenching is carried out within a quenching period, and (e) cooling at least one cooling portion (11) of the aluminum sheet material at a temperature that is = a cooling temperature, preferably ambient temperature, where cooling is carried out within a cooling period, which is greater than the quenching period, and shielding of the cooling portion using a tool takes place during quenching. Independent claims are also included for: (1) the aluminum sheet material having tailored material properties, manufactured by the above mentioned method, where the cooling portion opposite to the deterrent portion exhibits a mechanical material property deviating by a differential amount, preferably a reduced yield strength and/or a reduced tensile strength, and where the differential amount is stable at least during a time interval for further processing, preferably forming; and (2) the tool for carrying out the above mentioned method, comprising two tool halves connectable with each other, where at least one of the tool halves includes an opening (6) for accessibility to the deterrent portion of the aluminum sheet material.

Description

The invention relates to a method for the heat treatment of aluminum sheet material, a tool for carrying out such a method and an aluminum sheet material heat-treated by such a method.

Aluminum sheet materials are known in various alloy compositions as a lightweight material by obvious prior use. Curing aluminum alloys are known which have silicon and magnesium as the main alloying elements. Other alloying elements can be included. Such aluminum alloys are grouped according to an international standard in a class called AA6xxx. Such AlMgSi alloys have a comparatively high formability, since the alloying elements silicon and magnesium are present in the production of the aluminum sheet material not in dissolved form but as a supersaturated mixed crystal. This material state is unstable in time, ie after the sheet metal production begins a spontaneous cold aging process, whereby the strength of the material increases and its formability is reduced. Alternatively, the aluminum sheet material may also be subjected to a thermal aging process. In addition, precipitation-hardenable aluminum alloys with the main alloying elements zinc and magnesium exist. These can be stored analogously cold and warm and are summarized under the name 7xxx. From the textbook "Continuous time-temperature precipitation diagrams of Al-Mg-Si alloys" by Milkereit, Shaker Verlag, In 2011, it is known that quenching at a quench rate following solution heat treatment of the aluminum alloy affects the hardness of the thus heat treated material. As the cooling rate decreases, the hardness and strength of the sheet material decreases.

From the DE 196 20 196 A1 and from the DE 10 2010 033 864 A1 are known methods for heat treatment of aluminum sheet material. Locally confined areas of a blank of the aluminum sheet material, also referred to as aluminum plate, are heated to effect localized softening of the material. This makes it possible to produce an aluminum plate having locally different material properties, which are optimized for example for a subsequent forming process. Later to be reshaped areas of the board are softened to facilitate a flow of material from these areas, while reducing the required forming forces. Areas of the board that have a force-transmitting function during forming are not softened. A subsequent forming process of the so-heat-treated board can be done in a cold state such as at room temperature. The methods mentioned require complex heat treatment strategies and tools such as laser beam sources, whereby a local heating of the sheet material must be ensured. In particular, for the mass production of heat-treated circuit boards for use in the automotive industry, such methods are hardly suitable. In addition, the heat treatment state of the boards is unstable in time due to the spontaneous onset of cold treatment process after the heat treatment. The incorporation of such a heat treatment process into a manufacturing process is complicated. A disturbance of the heat treatment process causes an interruption of a possibly subsequent forming process.

The invention is therefore based on the object to provide a method for heat treatment of aluminum sheet material such that an adjustment of locally tailored material properties of the aluminum sheet material is facilitated.

This object is solved by the features of claim 1. The core of the present invention is that the material properties of aluminum sheet material are locally adjustable differently by different cooling processes are locally applied differently on the aluminum sheet material. By various cooling processes is meant that the cooling operations are carried out at different cooling rates, i. that the cooling of the aluminum sheet material is forced locally at different speeds. It is advantageous if the aluminum sheet material is available as an aluminum plate, since the temperature control is possible both during heating and during cooling with higher accuracy. But it is also possible, the aluminum sheet material, for. with a reel in the form of a sheet metal strip continuously to provide. As a result, the discharge rate of the method can be increased because a separate handling of individual blanks is not required.

During the heat treatment, the aluminum sheet material is first heated to a temperature equal to or higher than a heating temperature. This heating step is also referred to as solution annealing. Depending on the alloy composition of the aluminum sheet material used, the heating temperature may vary. For hardenable Aluminum alloys with the alloying constituents silicon and magnesium, so-called AlMgSi alloys such as AA6016 or AA6181, may have the heating temperature for solution annealing in the range between 480 ° C and 540 ° C. The temperature is maintained at a temperature level equal to or higher than the heating temperature during a heating period, which may be about one hour, for example. For AA6060, the solution annealing time is about 20 minutes. The maintenance of the heating time ensures a release of the alloy components to a sufficient extent. Subsequently, a quenching of at least one quenching region of the aluminum sheet material takes place. The temperature of the aluminum board is lowered from the heating temperature to a temperature less than or equal to a quenching temperature. The quenching takes place within a quenching time, which may be, for example, more than 100 K / s, in particular more than 160 K / s. As a result of the quenching, ie by the cooling within a short time, diffusion-controlled precipitation processes are suppressed, so that the alloying elements are in a positively dissolved state. In at least one quench zone, the aluminum sheet material has, for example, a comparatively high yield strength and a high tensile strength. Furthermore, a cooling of at least one cooling region of the aluminum sheet material to a temperature less than or equal to a cooling temperature, which may be, for example, the ambient temperature. The ambient temperature may be, for example, room temperature. The cooling takes place within a cooling period, wherein the cooling time is greater than the quenching time. This means that at least one cooling zone is cooled at a lower cooling rate than quenching at least one quench zone. The deterrent area and the cooling area may be adjacent but geometrically separated from each other. The two areas do not overlap. As a result, the quench area and the cooling area have different mechanical properties from each other. In particular, it is possible, for example, to deliberately reduce the yield strength and / or the strength in the cooling region compared with the corresponding values in the quench region. It has turned out to be particularly advantageous that a difference of the adjusted material properties in the quenching area and in the cooling area is qualitatively temporally stable. This means that, despite a spontaneous onset of cold aging, a differential amount of the mechanical properties generated as a result of the heat treatment remains essentially approximately unchanged. For example, a downstream forming process, in particular temporally and spatially, can be decoupled from the heat treatment of the aluminum sheet material.

The method of heat treatment according to the present invention enables the production of aluminum sheet material with locally tailored, high-quality time material properties. In particular, it is possible to adjust the material properties directly during the production of the aluminum sheet material. Downstream heat treatment, which occurs in the prior art processes through additional local heating of prefabricated sinkers, is not required in the present process. It is also possible to use the method according to the invention for an already produced, in particular hardened, aluminum plate, for example in a sheet metal processing plant, such as automobile or aircraft manufacturer or their suppliers.

In particular, it is possible to provide a plurality of cooling regions and / or a plurality of quenching regions on the aluminum plate. In addition, it is possible to provide deterrent areas, wherein the respective quenching durations of the deterrent areas are different from each other. This makes it possible to produce an aluminum plate with a greater variety of design with regard to the mechanical properties to be set. In particular, it is possible to adjust adjacent quench areas such that a gradual transition of the material properties such as from a high tensile strength in the quench area to stepwise reduced strengths in other quench areas is realized. Essential for the adjustment of the material properties is the quench rate, d. H. one cooling per time.

In a method according to claim 2, the quenching rate and thus the quenching time can be adjusted. The heat dissipation from the at least one quench area of the aluminum board is increased by a quench medium against cooling in air. Water is particularly suitable as a quenching medium and in particular available in many places. In particular, the quenching is carried out by deliberately supplying the quenching medium in the quenching area. It is also possible to use other quenching media, especially oil or gaseous quenching media such as N ₂ or CO ₂ .

In a method according to claim 3, the cooling of at least one cooling zone takes place in air. Such a cooling process can be implemented with little equipment. The cooling can be additionally delayed by the fact that the cooling area is covered by steel plates. In this case, the steel plates act as heat storage, so that a slower dissipation of heat from the cooling area over the steel plates to the environment results.

In a method according to claim 4, the quenching with high reliability is feasible. In particular, accidental quenching of the cooling region can be avoided since the at least one cooling region is shielded by means of a tool. In the event that quench medium undesirably comes into contact with the tool during quenching, this results in cooling of the tool, with cooling being delayed as compared to quenching. Due to the contact of the quenching medium with the tool, it will cool down faster in the edge regions. The result is a heat transfer area, which is reflected in the strength distribution.

In a method according to claim 5, the procedure and the implementation are additionally simplified. The fact that the aluminum sheet material is already placed in a tool before heating and heated together with this, it can be avoided to have to insert the aluminum sheet material in a heated state in an optionally cold tool. The handling of the aluminum sheet material is simplified.

A method according to claim 6 enables a targeted design of an aluminum plate to be produced with locally tailored material properties. By means of a numerical calculation method, it is possible to calculate both required mechanical properties as well as their arrangement and extent on the board for subsequent shaping of the board. Based on the thus calculated Distribution of mechanical properties, cooling ranges and quenching ranges can be set for the heat treatment.

It is a further object of the present invention to provide aluminum sheet material having locally tailored material properties.

This object is solved by the features of claim 7. The essence of the invention is that aluminum sheet material is heat treated by the method described above. Such a heat-treated sheet metal material has in particular qualitatively time-stable mechanical properties.

An aluminum sheet material according to claim 8 allows and / or simplifies a downstream forming process.

An aluminum sheet material according to claim 9 ensures a further processing, in particular a deformation, of the aluminum sheet material with a time interval. A time interval within which a difference in mechanical properties between the at least one quench zone and the at least one quench zone is stable is in particular more than 50 hours, in particular more than 150 hours and in particular more than 1000 hours. This makes it possible to decouple the Blechherstellungs-, Blechwärmebehandlungs- and Blechumformprozess from each other. In particular, it is possible to produce the sheet material at a first location such as in a sheet metal manufacturing operation and subjected to a corresponding heat treatment and then at a further location such as a further processing operation, in particular for Sheet metal forming to be transported at an automobile manufacturer, wherein a difference in the mechanical properties does not change within a permissible, predefined time interval between sheet metal manufacturing and - processing. For the further processing of a board produced in this way, it may be advantageous to analyze by means of a reference component which has been heat-treated identically, such as the cooling zone or the quench zone, in order to be able to infer further material parameters required for the deformation of the aluminum board.

In an aluminum sheet material according to claim 10, a reduction of a required forming force is possible on a large scale.

• Klasse 6xxx: Al Mg Si
• Klasse 2xxx: Al Cu (Si, Mn), A1 Cu Mg, A1 Cu (Mg) Li
• Klasse 7xxx: Al Zn Mg, Al Zn Mg Cu

An aluminum sheet material according to claim 11 has been found to be particularly suitable for adjusting a profile of the material properties according to the present invention. These hardenable aluminum alloys can be summarized as follows:

• Class 6xxx: Al Mg Si
• Class 2xxx: AlCu (Si, Mn), AlCuMg, AlCu (Mg) Li
• Class 7xxx: Al Zn Mg, Al Zn Mg Cu

It is another object of the present invention to provide a tool that facilitates heat treatment of aluminum sheet material.

This object is achieved with a tool according to claim 12. The essence of the invention lies in the fact that the tool is made in two parts and comprises two tool halves which can be connected to each other, wherein at least one of the tool halves has an opening such that a quench area of the aluminum board is accessible from outside the tool. This tool half is designed like a mask. The opening may for example be designed as a recess in the form of a bore of the mold half. It is also possible that the opening is made in the edge region of the mold half. In particular, it is possible that a plurality of mutually different openings are provided for producing a plurality of quench areas of the aluminum plate. This makes it possible to purposefully quench the quenching areas of the aluminum plate through the openings, optionally separately, with a quenching medium. The remaining, inaccessible areas of the aluminum plate thus represent the cooling areas that are protected by the tool from being quenched by the quench medium. In addition, the thickness of the tool can be varied locally and thus the cooling rates can be customized. The same effect can be achieved by using locally different materials, such as copper instead of steel. The tool according to the invention is easy to manufacture and allows direct and uncomplicated performance of a locally tailored deterrent process.

A tool according to claim 13 is uncomplicated and in particular cost-reduced to produce. In particular, it is possible to produce the plate-shaped mold halves made of steel. On the one hand, steel is easy to process and thus simplifies the manufacture of the tool itself. In addition, steel is well suited to deliver the heat absorbed during the heating in the manufacture of the aluminum board in the cooling areas continuously and delayed with respect to the quenching areas. Steel plates as mold halves can serve as a buffer in the Heat emission act. A softening in the cooling areas is additionally secured. Unintentional quenching of the cooling areas can be avoided. It is also possible to use other tool materials.

Fig. 1

eine schematische Perspektivdarstellung einer Aluminiumplatine in einem erfindungsgemäßen Werkzeug,

Fig. 2

eine schematische Darstellung der wärmebehandelten Aluminiumplatine gemäß Fig. 1 mit Kennzeichnung von Bereichen lokal variierender mechanischer Eigenschaften,

Fig. 3

eine schematische Darstellung eines Profils der Werkstoffeigenschaften entlang einer Linie III-III in Fig. 2,

Fig. 4

eine schematische Darstellung eines Temperatur-Zeit-Ablaufs der Aluminiumplatine bei der Durchführung des erfindungsgemäßen Verfahrens zur Wärmebehandlung, und

Fig. 5

eine Darstellung einer ausgewählten mechanischen Eigenschaft eines Abschreckungsbereichs und eines Abkühlungsbereichs einer wärmebehandelten Aluminiumplatine.

Further features, details and advantages of the method according to the invention, the corresponding tool and aluminum sheet material produced therewith are explained in more detail below with reference to the description of an embodiment with reference to the drawings. Show it:

Fig. 1

a schematic perspective view of an aluminum plate in a tool according to the invention,

Fig. 2

a schematic representation of the heat-treated aluminum plate according to Fig. 1 marking areas of locally varying mechanical properties,

Fig. 3

a schematic representation of a profile of the material properties along a line III-III in Fig. 2 .

Fig. 4

a schematic representation of a temperature-time-course of the aluminum plate in carrying out the method according to the invention for the heat treatment, and

Fig. 5

a representation of a selected mechanical property of a quench area and a cooling area of a heat treated aluminum plate.

According to Fig. 1 a tool 1 according to the invention comprises an upper mold half 2 and a lower mold half 3. The two mold halves 2, 3 are substantially identical and each have one of the other mold half 2, 3 facing tool inside 4 and one on the respective mold half 2, 3 of the tool inside 4 opposite tool outside 5 on. The upper and lower mold halves 2, 3 each have an aligned opening 6, which allow a passage from the tool outer side 5 to the tool inner side 4. According to the exemplary embodiment of the tool 1 according to the invention, the openings 6 have a circular basic shape in a plane oriented parallel to the tool sides 4, 5. It is also possible that the openings 6 are made with a different basic shape. The openings 6 have a longitudinal axis 7, which is oriented perpendicular to the tool sides 4, 5 according to the embodiment shown. It is possible that in the tool 1 more, in particular independent openings are provided. The openings can, as in Fig. 1 shown, having a basic shape with a closed contour, so be disposed within the respective mold half 2, 3. It is also possible that one or more openings are arranged in an edge region of the respective tool half 2, 3.

The tool halves 2, 3 are plate-shaped and made of steel, especially made of stainless steel. In order to connect the two mold halves 2, 3 with each other, a plurality of screws, not shown, may be provided, for example in corner regions of the rectangular, in particular square, base of the tool halves 2, 3. There are also other types of connection for the two mold halves 2, 3 conceivable. For example, it is possible, the two mold halves 2, 3 along an outer edge by means of a hinge pivotally connect to each other and lock by a arranged on a hinge outer edge disposed closure. Such a connection facilitates opening and closing of the tool 1.

Between the two mold halves 2, 3, an aluminum plate 8 is arranged. The aluminum plate 8 is in each case on the tool inside 4 of the tool halves 2, 3 at. The aluminum plate 8 is a sheet metal blank made of an aluminum alloy, in particular of a hardenable aluminum alloy, such as an AlZnMg (Cu) alloy or AlMgSi alloy, in particular AA6014, AA6016 or AA6181. According to the embodiment shown, the aluminum plate 8 has a circular base. Depending on the intended further processing, the blank is selected accordingly. The blank of the board 8 shown can be used for the production of a cylindrical cup.

Through the openings 6 in the mold halves 2, 3 arranged in the tool 1 aluminum plate 8 from outside the tool 1 is accessible. The openings 6 are surrounded by a shielding section 9 of the tool halves 2, 3. The shielding section 9 is used during quenching of the arranged in the tool 1 aluminum plate 8 for shielding arranged underneath areas of the aluminum plate 8, which will be explained in more detail below. In addition, the shielding portion 9 is used for controlled and delayed heat release from the aluminum plate 8 on the tool halves 2, 3 to the environment.

The tool halves 2, 3 may have a collar (not shown) projecting beyond the aluminum plate 8, which protrudes beyond the respective tool inner side 4, so that a gap between the two tool halves 2, 3 is closed. This avoids that heat is released via the end faces of the aluminum plate 8 during cooling of the tool 1 with the aluminum plate 8 disposed therein.

By the two tool halves 2, 3 are made identical with openings 6, the aluminum plate 8 is accessible from both sides on the outside. In particular, in the heat treatment of thick sheet metal with a sheet thickness of, for example, greater than or equal to 2 mm is thus ensured that the material properties are distributed homogeneously along the sheet thickness. An only one-sided opening 6 in one of the two mold halves 2, 3 is also conceivable.

Fig. 2 shows a schematic representation of an aluminum plate 8 according to the invention, which in the tool 1 according to Fig. 1 has been heat treated. The aluminum plate 8 comprises a centrically arranged circular deterrent area, which is shown hatched, and a cooling area 11 surrounding the deterrent area 10.

According to the qualitative representation in Fig. 3 the aluminum plate 8 in the quenching region 10 has an increased yield strength R _p0 , ₂ . Analogously, the relationship shown - ie increased mechanical characteristics within the quench zone 10 and compared to reduced mechanical characteristics in the surrounding cooling zone 11 - for example, for the tensile strength R _m or the hardness of the material. A difference ΔW between the material properties in the quench zone 10 and in the cooling zone 11 is at least 25% of the respective mechanical material property of the quench zone 11 and in particular up to 50% of the respective mechanical material property of the quench zone 11. This is especially true for the aluminum alloys AA6016 T4 or AA6181.

As in Fig. 3 indicated, the yield strength R _p0 , ₂ along the profile of the aluminum plate 8 has no exactly stepped course. At the edges of the regions 10, 11 a transition region is given in each case.

The following is based on the Fig. 1 and 4 the method according to the invention for heat treatment of the aluminum plate 8 explained. Initially, the aluminum plate 8 is provided. This can be, for example, a substantially untreated aluminum plate in semifinished production, for example, in a sheet metal forming operation. It is also possible for an already manufactured and delivered aluminum plate to be subjected to the method explained below. The provided aluminum plate 8 is inserted into the tool 1. Subsequently, the tool 1 is closed and the two tool halves 2, 3 connected to each other, so that the aluminum plate 8 between the two mold halves 2, 3 is securely held. For the subsequent heat treatment and in particular for a final cooling of the tool 1 and the aluminum plate 8 located therein, it may be advantageous to design the tool 9 such that the contact pressure between the respective tool half 2, 3 and the aluminum plate 8 is adjustable. This is possible, in particular, by means of a hydraulic closing unit of the tool 1, wherein pressure sensors can be integrated in the tool halves 2, 3 such that a respective contact pressure can be determined. Via a central machine control, the is in signal communication with the hydraulic clamping unit and / or the pressure sensors in the tool halves 2, 3, a contact pressure during the heat treatment and in particular during the heating and / or the subsequent cooling can be monitored and regulated. In particular, it is possible to change the contact pressure by means of the hydraulic closing unit during the heat treatment.

The aluminum plate 8 is heated from an ambient temperature T _u together with the tool 1 to a temperature T which is greater than or equal to a heating temperature T _er . The heating or heating, for example, take place in a furnace, not shown. Such a heating strategy is straightforward and inexpensive to implement. There are also other heating strategies possible, with a continuous, homogeneous heating of the aluminum plate 8 and the tool 1 should be sought. The aluminum alloy according to the illustrated embodiment is AA6016 and is in a cold-cured state. The heating temperature in this case is T _er = 550 ° C.

After reaching the heating temperature T _he is held during a heating time T _he . In the embodiment shown, the heating time is t _he one hour. During the heating period, the alloying components are dissolved in the aluminum base material. This process step is also referred to as solution annealing.

Subsequently, the tool 1 with the aluminum plate 8 inserted therein is removed from the oven and the quenching area 10 of the aluminum plate 8 is quenched. This is done by the over the openings 6 accessible from outside the tool 1 deterrent area 10 is acted upon with water as the quenching medium. The water has a temperature lower than the ambient temperature T _u before quenching. This can be, for example, the temperature at which the water is taken from a conventional service water line. This temperature is for example between 10 ° C and 15 ° C. Thereby, the quenching area 10 of the aluminum board 8 is quenched to a temperature _lower than or equal to a quenching temperature T _schr . The quenching temperature T _schr is, for example, the ambient temperature T _u of about 20 ° C. The quenching takes place within a quenching time t _schr , which is a few seconds, in particular less than one second. Essential for the adjustment of the mechanical properties in the quench zone 10 is the cooling rate, which is also referred to as the quench rate. In the embodiment shown, the cooling rate is 161 K / s. The temperature control during quenching within the quench zone 10 is shown in the schematic diagram in FIG Fig. 4 represented by the solid line AS 10.

The temperature profile of the aluminum board 8 in the cooling zone 11 is in terms of heating and maintaining the temperature during the heating time t _he identical with the temperature-time profile within the quenching region 10. Since the cooling area is shielded by the shielding portion 9 of the upper tool half 2 11, the cooling zone 11 does not come into direct contact with the quenching medium water. Correspondingly, the cooling region 11 cools with a cooling rate of, for example, 0.8 K / s, which is reduced compared to the quenching region 10. This cooling rate results from the cooling of the steel plates 2, 3 by free convection to the environment. Cooling is considered complete when the cooling area 11 of the aluminum plate 8 has dropped to a temperature less than or equal to a cooling temperature T _k . The cooling temperature T _k may be, for example, the ambient temperature T _u . The cooling takes place within a cooling time t _k . The cooling time is greater than the quenching time t _schr . The outer areas of the board are usually cooled slowly for 10-15 minutes. Once a temperature of about 200 ° C is reached, a slow cooling is no longer necessary. Then the entire tool can be quenched to room temperature with water. The cooling curve of the cooling area 11 is in Fig. 4 represented by a dash-dot line AK11.

Depending on the requirement of a subsequent further processing process such as a forming process of the heat-treated aluminum sheet material described above, it may be useful to provide several, in particular independent deterrent regions 10 on the board 8. Accordingly, it is necessary to provide a tool 1 with differently arranged openings 6. The design of the tool 1 and in particular the arrangement, size and distribution of the openings can be done by means of a numerical calculation method. In order to realize different cooling rates in different areas of quenching, for example, different quenching media can be used. It is also possible that a quenching medium, such as water, may be used, with the temperature of the water prior to quenching chosen to be different for the different quench zones. Accordingly, different cooling rates result, which lead to different mechanical properties in said deterrent areas. This makes it possible, for example, a transition of mechanical properties between a deterrent region 10 and the Cooling area 11 as in Fig. 3 illustrated, gradually reduced by several deterrent regions map, so as to set a multi-stage, quasi-continuous gradient of the material properties in the board 8.

Fig. 5 shows a schematic representation of the yield strength R _p0 , ₂ within the quench _zone 10 and the cooling _zone 11 for the in Fig. 2 Shown is the yield strength R _p0 , ₂ as a function of a storage period t _{L of} the aluminum plate 8. At time t ₀ , the regions 10, 11, the yield strength R _p0 , ₂ , in Fig. 3 are shown. As is known from the prior art, also in the case of the aluminum plate 8, a spontaneous cold aging process takes place, which leads to a hardening of the regions 10, 11. Since, however, in the method according to the invention, the entire board 8, ie the quench zone 10 and the cooling zone 11 are equally heated and solution-annealed, the subsequent cold aging takes place concurrently, ie a difference ΔW between the yield point R _p0 , ₂ for the quench _zone 10 and the Cooling area 11 does not change with the storage time t _L advancing. That is, the absolute solidification is the same in both areas 10, 11. This in Fig. 5 Exemplary for the yield strength R _p0 , ₂ shown material _behavior applies equally to the tensile strength R _m . This means that the aluminum plate 8 has time-stable, locally tailored mechanical material properties.

In particular, this makes it possible to carry out a sheet metal processing, for example by forming with a greater time delay compared to an upstream heat treatment, the material properties and in particular the differences in the material properties between the softened cooling area and the quenching area. This is a significant advantage over the known from the prior art method of local heat treatment for softening localized material areas. There, only the locally softened areas are subject to a spontaneous cold aging, since only these areas were locally heat treated. Correspondingly, cold work hardening in the case of a locally heat-treated board successively leads to a change in the ratios of the material properties. In particular, a difference between the material properties of the softened, heat treated area and the base material is variable with increasing storage time t _L.

After heat treatment and forming, the board can be stored in a warm condition.

Claims (13)

Process for the heat treatment of aluminum sheet material, comprising the process steps Providing aluminum sheet material (8), Heating the aluminum sheet material (8) to a temperature (T) greater than or equal to a heating temperature (T _er ), Holding the temperature (T) during a heating period (t _er ), Quenching at least one quench zone (10) of the aluminum sheet material (8) to a temperature (T) equal to or lower than a quenching temperature (T _schr ), the quenching taking place within a quenching period (t _schr ), - cooling at least one cooling zone (11) of the aluminum sheet material (8) to a temperature (T) less than or equal to a cooling temperature (T _k ), in particular ambient temperature (T _u ), wherein the cooling within a cooling time (t _k ), the greater is the quenching time (t _schr ). A method according to claim 1, characterized in that the quenching takes place by applying the quenching region (10) with a quenching medium, in particular with water. Method according to one of the preceding claims, characterized by the cooling in air, in particular by free convection occurs. Method according to one of the preceding claims, characterized by shielding the cooling area (11) by means of a tool (1) during quenching. A method according to claim 4, characterized in that the aluminum sheet material (8) before heating in the tool (1) is inserted and heated together with the tool (1). Method according to one of the preceding claims, characterized by determining the cooling region (11) and the quenching region (10) by means of a numerical calculation method. Aluminum sheet material produced by a method of the preceding claims, wherein the aluminum sheet material (8) has locally tailored material properties. Aluminum sheet material according to claim 7, characterized in that the cooling zone (11) relative to the quench zone (10) by a difference (ΔW) deviating mechanical material property, in particular a reduced yield strength (R _p0 , ₂ ) and / or a reduced tensile strength (R _m ), having. Aluminum sheet material according to claim 8, characterized in that the difference (ΔW) at least during a time interval (t _um ) for further processing, in particular for a forming, is stable. Aluminum sheet material according to claim 8 or 9, characterized in that the difference (ΔW) has at least 25% of the mechanical material property of the quenching region (10). Aluminum sheet material according to one of claims 7 to 10, characterized in that the aluminum sheet material (8) has a hardenable aluminum alloy. Tool for a heat treatment of aluminum sheet material, comprising two mutually connectable tool halves (2, 3), wherein at least one of the tool halves (2, 3) has an opening (6) for access to a quenching region (10) of the aluminum sheet material (8). Tool according to claim 12, characterized by plate-shaped tool halves (2, 3), which are in particular made of steel.

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