WO2020182613A1

WO2020182613A1 - Flat product package, method for producing a material composite, and use thereof

Info

Publication number: WO2020182613A1
Application number: PCT/EP2020/055856
Authority: WO
Inventors: Jens-Ulrik Becker; Stefan Myslowicki
Original assignee: Thyssenkrupp Steel Europe Ag
Priority date: 2019-03-13
Filing date: 2020-03-05
Publication date: 2020-09-17
Also published as: DE102019203402A1

Abstract

The invention relates to a three-layer flat product package (10) having two outer layers (I, III), each consisting of a first workpiece (1), and a core layer (II) comprising at least one second workpiece (2, 3), wherein the workpieces (1, 2, 3) are stacked atop each other and define the three layers (I, II, III) of the flat product package (10), wherein the workpieces (1, 2, 3) form a horizontal connection plane (Vh) between the layers (I; II; III) and are interlockingly connected to each other circumferentially, at least in portions, wherein the flat product package (10) for hot roll cladding is provided in order to produce a material composite, wherein the flat product package (10) has a longitudinal extension (L) and a transverse extension (Q) and the longitudinal extension (L) is at least twice as long as the transverse extension (Q). The invention further relates to a method for producing a material composite and a use of the material composite.

Description

Flat product package, method for producing a composite material and its use

Technical area

The invention relates to a three-layer flat product package with two outer layers each consisting of a first workpiece and a core layer comprising at least one second workpiece, the workpieces being stacked on top of one another and defining the three layers of the flat product package, the workpieces forming a horizontal connec tion level between the layers and are at least partially circumferentially cohesively connected to one another, the flat product package being intended for hot-roll cladding to produce a material composite, the flat product package having a longitudinal extension and a transverse extension and the longitudinal extension being at least twice as long as the transverse extension. Furthermore, a method for producing a composite material and a use of the composite material is specified.

Technical background

In order to implement lightweight construction in automobile construction, various approaches have been developed in order to set areas with different properties in components which make it possible to meet locally different requirement profiles. When steel materials are used as semi-finished products, these approaches include technologies such as tailored blanks, tailored tempering, partial press hardening or flexible rolling. All mentioned technologies contain technically limiting aspects that have to be taken into account when using them, or they can lead to high costs in production and / or processing, which in turn affect profitability.

The tailored blanks, tailored tempering and partial press hardening technologies basically make it possible to set areas with different properties in a component, with a transition area always being formed between the partial areas.

In the case of a tailored blank, two or more blanks, which essentially consist of a steel material with different thicknesses and / or different qualities, are welded together to form a pre-blank, in particular in the butt joint, from which a component is then produced by cold and / or hot forming . The transition area is created by the weld seam and the adjoining heat-affected zones and especially the width can be set very narrow. In addition, welding points within a construction usually form a weak point, which must be taken into account when designing a construction.

With tailored tempering and partial press hardening, pre-blanks, in particular consisting of a hardenable steel material from which a component is to be formed in particular warm, are heated to different temperatures locally or cooled differently in the warm state in order to produce locally different target structures with corresponding properties adjust. The properties result from the temperature control during the manufacture of the component. In the context of series production of components, a high cycle frequency is desirable for reasons of economy. This places high demands on the manufacturing process, for example that a forming tool u. a. targeted cooling at the transition between two different property areas, so that there is no undesired heating of the forming tool and thus no change in the local cooling conditions. In addition, this is about the

Technology that operates over time / temperature is only possible to a limited extent, the width of the transition area is clearly defined and reproducible.

With flexible rolling, on the other hand, the component receives its locally different properties from a locally varying material thickness. This must be taken into account when processing a (steel) strip into a component and is fundamentally a challenge. Exact positioning of a transition area in a manufactured component can only be done within limits. In principle, this technology can be used to set defined transition areas with different widths. However, the processing of a strip of varying thickness places high demands on process management and process control.

Another technology is the production of multi-layer steel material composites by roll cladding, in particular hot roll cladding, which is known from the prior art. For this purpose, a first and at least one second flat product are provided, the flat products differing from one another with regard to at least one property. The flat products are stacked on top of one another, with at least the surfaces of the flat products that are assigned to one another and to be connected being cleaned and / or removed before being stacked on top of one another. The individual flat products are at least regionally welded to one another to produce a flat product package. The flat product package is heated to at least one initial hot rolling temperature and then hot rolled to form a hot strip, the hot strip then being formed into sheets can be cut off or reeled into a bundle, cf. German patent DE 10 2005 006 606 B3. For the production of multi-layer steel material composites, the flat products built up to form a flat product package, which consist of different materials / layers and are especially welded all around and thus fixed, are transported together through the roll gap of a roll stand and thus reduced in thickness. The thickness is further reduced with each stitch.

The setting of locally different properties in a steel material composite has also already been described in the prior art, in particular in the German Offenlegungsschrift DE 10 2014 114 365 A1. Two different steel materials are combined with one another in a layer thickness ratio that differs over the strip thickness, the structure being designed with five layers, consisting of a core layer, two intermediate layers and two outer layers. The core layer and the two outer layers are each made continuous, so that the variation of the locally different properties takes place through the targeted design of the intermediate layers. Due to the number of composite layers, the manufacturing effort in the manufacture of rolled packs or flat product packs is enormous.

Further five-layer steel material composites, in particular with more than two different steel materials, are described in the prior art, for example in the German patent applications DE 10 2017 208 254 A1 and DE 10 2007 022 453 A1.

Summary of the invention

The invention is therefore based on the object of providing a flat product package and of specifying a method for producing a hot-rolled material composite with which, in particular, a graduated setting of areas of different properties in a component can be made in a targeted manner, preferably within narrow tolerances, reproducibly and economically can.

This problem is solved by a flat product package with the features of claim 1.

According to the invention, it is provided that the core layer comprises at least one third workpiece which differs from the first workpiece and / or from the second workpiece in terms of at least one property, the second workpiece and the third workpiece within the core layer are posi tioned running alongside one another in the longitudinal direction, the second workpiece and the third workpiece between them form a reference surface which separates the workpieces from one another.

Two second workpieces are preferably provided, the second workpiece and the third workpiece being positioned in the core layer in such a way that the second workpiece is arranged laterally in transverse extension and the third workpiece is arranged within the core layer between the second workpiece in each case. The first two workpieces can be made of different materials. The second or the second workpieces can also consist of different materials. At least one of the first workpieces can consist of the same material as at least one of the second workpieces. The third workpiece can also consist of a material which is provided for at least one of the first workpieces or at least one of the second workpieces. The two outer layers (first workpiece / first workpieces) are preferably made of the same material (first material) and, in particular, the second workpiece (s) arranged laterally in the core layer in the transverse direction of the flat product package consist of the same material (second material), it can be ensured that the same deformation ratios are set at the top and bottom during hot roll cladding, and the same deformation ratios are set laterally in the longitudinal extension (in the rolling direction) of the flat product package, so that essentially simple hot roll cladding can take place.

Due to the restriction to three layers, compared to a five-layer structure, on the one hand, the manufacturing effort in the manufacture of the flat product package is reduced. In particular with regard to DE 10 2014 114 365 A1, the limiting factor regarding the setting of the width of the transition between the areas of different properties must be taken into account, so that, on the other hand, the setting of the width of the areas of different properties already during the assembly of the flat product package ( Rolling package) it follows, since both during hot rolling and optionally subsequent cold rolling there is essentially no flow in the transverse direction but essentially only flow in the longitudinal direction (rolling direction).

The two outer layers are preferably formed in one piece throughout. The second and / or third workpiece in the core layer of the flat product package is also preferably formed in one piece in the longitudinal direction. If two second workpieces are provided laterally within the core layer, the third workpiece is basically on four sides covered up and down by the two outer layers and laterally within the core layer by the second workpieces. The second workpieces shield the third workpiece laterally in the longitudinal direction. The third workpiece is only not covered at the two ends, also called front sides, of the flat product package. On the front sides of the flat product package, all workpieces are visible in cross section when viewed in cross section. The second workpiece and the third workpiece form between them (each) a reference surface which separates the workpieces from one another within the core layer.

The flat product package has a longitudinal extent and a transverse extent, the longitudinal extent being at least twice as long compared to the transverse extent, the longitudinal extent being in particular at least three times the length, preferably at least five times the length, preferably at least ten times the length.

The two outer layers can in particular each be provided as a flat product, which defines a length, a width and a height, in the form of a cast slab, pre-rolled slab, bloom, pre-plate, heavy plate or pre-strip, as a first workpiece made of a first or different materials. The second and third workpiece for the core layer can also be made available as a flat product made of a second or different material, in particular with a rectangular cross-sectional shape. The cross-sectional shape of the second and third workpiece can also deviate from the rectangular shape, especially if the width of the transition between areas with different properties is to be influenced, the third workpiece, which is in the core layer, if for example two second workpieces are provided , is covered from the sides in the longitudinal extension (rolling direction) by the second workpiece, can have a cross-section in triangular, square or polygonal shape and the second workpiece on the side facing the third workpiece (on the side of the reference surface) has the shape of the third workpiece corresponds or is adapted accordingly. The side of the second workpiece facing away from the third workpiece is essentially flat and runs essentially flat in relation to the outer layers in the longitudinal direction. Depending on the design, the second and third workpiece can be made of a particularly cast, preferably rectangular material, for example, machined to the desired cross-sectional shape, which can be time-consuming and costly, or alternatively, cast directly, preferably using suitable molds with a final cross-section, and cut to length to be positioned accordingly in the flat product package. In the simplest embodiment, for example, only a second and a third workpiece are arranged within the core layer, which are separated from one another in a transverse direction via a reference surface.

The property of the workpiece includes mechanical parameters, at least tensile strength, hardness, elongation at break, flow stress, deformation resistance; Coefficient of friction; High temperature strength; To understand linear expansion, thickness of the respective flat product and / or the chemical composition.

According to one embodiment, the workpieces each consist of a steel with a first steel alloy, a second steel alloy and optionally a third steel alloy. By using at least two, preferably three different steel materials / alloys, it is also possible to influence the properties of the material composite to be produced or the resulting component to a greater extent than before. In the design of composite materials to be manufactured, two steel materials have been used so far, cf. DE 10 2014 114 365 A1, combined with one another, which are intended to optimize different aspects. A high-strength or ultra-high-strength steel material, for example with a tensile strength of at least 800 MPa, should increase the strength in the material composite, while a soft steel material, for example with a tensile strength of up to a maximum of 650 MPa, should have properties such as ductility, welding behavior and / or should have a positive effect on the resistance to delayed crack formation in the composite material. In order to be able to implement this in a targeted manner, various minimum proportions are necessary in particular. When building a flat product package with three different steel materials, the properties in the individual areas, in particular in the material composite to be manufactured or in the resulting component, can be more finely differentiated and / or the local requirements can be influenced more finely.

For example, the first steel alloy has a carbon content of up to and including 0.1% by weight, the second steel alloy has a carbon content of at least 0.15% by weight and the optional third steel alloy has a carbon content of at least 0.02% by weight Compared to the second steel alloy is higher. Such a combination is preferably suitable for press hardening. Another combination with, in particular, lower carbon contents in the design of the second and / or the optional third steel alloy and / or with a higher carbon content in the design of the first steel alloy tion are also conceivable, for example, in particular for cold forming or semi-warm forming.

Alternatively, aluminum alloys, copper alloys, nickel-based alloys, titanium alloys or magnesium alloys can also be used as material (s).

According to one embodiment, the reference surface is at an angle a1 = 0.1 ° to 90 °, in particular a1 = 5 ° to 80 ° and / or a2 = 90 ° to 179.9 °, in particular a2 = 100 ° to 175 ° to the transverse strut The package of flat products is aligned, with al with the exception of 90 ° being an acute angle and a2 with the exception of 90 ° being an obtuse angle. By setting the angle of the reference surface between the second and third workpiece within the core layer and in particular taking into account their proportions, in other words taking into account or setting the thickness of the core layer, based on the total thickness of the flat product package, can influence to the width of the transition area (Be rich between different properties).

According to a second aspect of the invention, the object is achieved with a method for producing a composite material having the features of claim 6. According to the invention, the method comprises the following steps: providing a flat product package according to the invention; Heating the flat product package to at least one hot rolling start temperature; Hot rolling of the flat product package to form a hot strip, the hot strip to be cut into plates, sheets or sheets; or winding the hot strip into a coil.

According to the invention, two outer layers each consisting of a first workpiece and a core layer comprising at least one second workpiece are provided, the first workpiece differing from the at least second workpiece with regard to at least one property (chemical composition, tensile strength, hardness and / or elongation at break, etc.). The workpieces (outer layers and core layer) are optionally cleaned and / or abraded at least on the surfaces to be connected of the first and / or the second workpiece in order to remove the rust layer formed on the surface, for example during storage of the flat products, and possibly others on the surface remove any sturgeon particles. After the optional cleaning and / or machining, the first and the at least second workpiece are stacked on top of one another in order to define the three layers of the flat product package, the workpieces between the layers having a horizontal Form zontal connection level and are at least partially connected to one another in a cohesive manner.

The flat product package is heated to at least one hot rolling start temperature, for example se in a flubber beam furnace at temperatures between 1100 and 1300 ° C., for example. After the minimum hot rolling start temperature has been reached, the flat product package is rolled into a hot strip according to a specific pass schedule, which forms the material composite or the hot-roll clad material composite, with the corresponding layers or workpieces / materials being formed both over the horizontal connecting plane (s) and over the Connect the reference surface (s) completely and firmly with one another. After rolling is complete, the hot strip is either cut to length into plates, sheets or sheets. Alternatively, the hot strip can be reeled into a coil.

According to one embodiment, the composite material or the hot strip can be rolled into a cold strip and then paneled into sheets or reeled into a coil.

According to one embodiment, the composite material can be coated with an inorganic and / or organic coating. Metallic coatings, in particular special anti-corrosion coatings based on zinc or aluminum, are preferably provided. The composite material is particularly preferably provided with an electrolytic or fire-coated coating.

According to a third aspect, the invention relates to a use of the material composite produced as part or component in areas with wear influences, in machine or plant construction, container construction, pipe construction, in the construction sector, in vehicle, rail, shipbuilding or in the aerospace industry. In particular, the part or component is cold-formed, semi-hot-formed, press-hardened or tempered.

Warm forming takes place at least in the case of a steel composite at a temperature above RT, in particular above 200 ° C to 700 ° C, in particular to reduce press forces and / or to be able to produce more complex and, in particular, low-resilience components. The press hardening can take place in the course of indirect hot forming or direct hot forming, a steel material composite being used and at least one of the materials being made of a hardenable steel. Indirect hot forming is a cold forming of an essentially flat semi-finished product into a preform with subsequent heating of the preform to a temperature above Acl and subsequent press hardening in a cooled tool to form a press-hardened component (final shape). Direct hot forming is to be understood as heating an essentially flat semi-finished product to a temperature above Acl and subsequent hot forming and press hardening in a cooled tool to form a press-hardened component. Press hardening does not necessarily have to cover the entire component, but can also only take place locally, depending on requirements and use.

Brief description of the drawings

The invention is explained in more detail below with reference to drawings. The same parts are always provided with the same reference symbols. Show in detail:

1 schematically shows a cross section through a flat product package according to a first

Embodiment,

2 schematically shows a cross section through a flat product package after a second

Embodiment,

3 schematically shows a cross section through a flat product package according to a third

Embodiment,

4 schematically shows a cross section through a flat product package according to a fourth

Embodiment,

5 schematically shows a cross section through a flat product package according to a fifth

Embodiment,

6 schematically shows a cross section through a flat product package according to a sixth

Embodiment

7 schematically shows a cross section through a flat product package according to a seventh

Embodiment and

8 shows a flow chart of a method according to an embodiment.

Description of the preferred embodiments In the figures 1 to 6 different embodiments of a flat product package (10) are shown. The flat product package (10) has a longitudinal extension (L), symbolized by a circle and an X within the circle and is intended to indicate the extension of the flat product package (10) into the image plane and thus also the rolling direction, and a transverse extension (Q), symbolized by a double arrow, with the longitudinal extension (L) being at least twice as long as the transverse extension (Q). The three-layer flat product package (10) according to the invention has two outer layers (I, III) each consisting of a first workpiece (1) and a core layer (II) comprising at least one second workpiece (2) and a third workpiece (3). The first workpiece (1) differs from the second workpiece (2) with regard to at least one property and the third workpiece (3) differs from the first workpiece (1) and / or from the second workpiece (2) with regard to at least one property. The workpieces (1, 2, 3) are stacked on top of one another and define the three layers (I, II, III) of the flat product package (10). The workpieces (1, 2, 3) each form a horizontal connection plane (Vh) between the layers (I; II; III) and are at least partially connected to one another in a materially bonded manner. The second workpiece (2) and the third workpiece (3) are positioned in the core layer (II) in such a way that the second workpiece (2) is arranged laterally in the transverse direction (Q) and the third workpiece (3) is arranged within the core layer ( II) is arranged between the respective second workpiece (2), the second workpiece (2) and the third workpiece (3) between them a reference surface (Ül, Ü2), in particular each a reference surface (Ül, Ü2) form which the workpieces (2, 3) separates or separate from each other. The flat product package (10) is intended for hot roll cladding to create a composite material.

The workpieces (1, 2, 3) are preferably made of steel with a first steel alloy (1), a second steel alloy (2) and a third steel alloy (3). In particular, different steel materials / alloys can also be provided for the first workpiece (1), that is to say different materials for the outer layers (I, III). In particular, different steel materials / alloys can be provided for the second workpiece (2), i.e. different materials for the second workpieces arranged laterally within the core layer (II) and laterally covering the third workpiece (3).

In Fig. 1, a cross section through a flat product package (10) according to a first embodiment of the invention is shown schematically. The first, second and third workpiece (1, 2, 3) are each designed as a flat product. The core layer (II) comprises a third workpiece (3) in the middle and a second workpiece (2), which is to the side, thus left and right, next to the third workpiece (3) arranged and ge over the reference surfaces (Ül, Ü2) separated from each other. Due to the rectangular cross-sectional shape of the workpieces (2, 3) there is a right angle between the workpieces (2, 3) to the transverse extension (Q) of the flat product package (10) of a1 = a2 = 90 °.

In Fig. 2, a cross section through a flat product package (10) according to a second embodiment of the invention is shown schematically. Compared to the embodiment according to Fi gur 1 there is no difference in the left side of the flat product package (10), whereas the right side of the flat product package (10) differs in the core layer (II) and the reference surface (Ü2) with an obtuse angle a2 is set, so that on the composite material to be manufactured or on the resulting component, at least in one area, a transition between the areas of different properties that is graduated compared to a right angle and therefore a finer one can be set.

In Fig. 3, a cross section through a flat product package (10) according to a third embodiment of the invention is shown schematically. In comparison to the embodiment according to FIG. 2, there is no difference between the right side of the flat product package (10), whereas the left side of the flat product package (10) in the core layer (II) is a mirror image of the right side and the reference surface (Ül) with is set at an acute angle al. The cross-sectional shape of the third workpiece (3) essentially corresponds to a trapezoidal shape.

In Fig. 4, a cross section through a flat product package (10) according to a fourth embodiment of the invention is shown schematically. Compared to the embodiment according to FIG. 3, the fourth embodiment differs in that the angle al of the reference surface (Ül) is larger, thus approaching a right angle, than the angle al in the embodiment in FIG. 3, so that the width of the transition area on the composite material to be manufactured or on the resulting component is smaller on the left than on the right, so the transition between the different properties is set differentiated on the right than on the left.

In Fig. 5, a cross section through a flat product package (10) according to a fifth embodiment of the invention is shown schematically. Compared to the embodiment according to FIG. 3, there is no difference in the left side of the flat product package (10), whereas the reference area (Ü2) on the right side of the flat product package (10) runs parallel to the reference area (Ü1) on the left of the flat product package (10) with a obtuse angle a2 is set. The cross-sectional shape of the third workpiece (3) essentially corresponds to a parallelogram shape.

In Fig. 6, a cross section through a flat product package (10) according to a sixth embodiment of the invention is shown schematically. In comparison to the embodiment according to FIG. 1, there is essentially no difference in the right side of the flat product package (10), whereas the second workpiece (2) on the left side and the third workpiece (3) each have a triangular cross-sectional shape and thus with one another over the Reference surface (Ül) are positioned in the core layer (II) so that they together form a rectangular cross-sectional shape and are separated from each other over the reference surface (Ül) at an acute angle al to the transverse extension (Q). This embodiment shows the transition between areas of different properties that can be adjusted as far as possible in terms of width.

In Fig. 7 a cross section through a flat product package (10) according to a seventh embodiment of the invention is shown schematically. Compared to the other embodiments, there is a difference in the core layer (II) of the flat product package (10), the core layer (II) being composed of only a second workpiece (2) and a third workpiece (3). The two workpieces (2, 3) can each have a substantially rectangular cross-sectional shape or, in order to be able to set an adjustable transition between the different properties, have a square cross-sectional shape with an inclined reference surface (not shown). They are positioned with one another within the core layer (II) in such a way that they over the reference surface (Ül) either at a right angle al = 90 ° to the transverse extent (Q) or at an acute angle al = 0.1 ° to 90 ° to the transverse extent (Q ) are separated from each other (not shown).

FIG. 8 shows a flow chart of an exemplary embodiment of a method according to the invention for producing a hot-roll clad material composite. There are two outer layers (I, III) each consisting of a first workpiece (1), preferably made of a steel with a first steel alloy (1), and a core layer (II) comprising a second workpiece (2) and a third workpiece (3 ), preferably each made of a steel with a second steel alloy (2) and with a third steel alloy (3), the first workpiece (1) differing from the at least one property (tensile strength, hardness and / or elongation at break, etc.) at least the second workpiece (2) and / or the third workpiece (3) differs from the first workpiece (1) and / or from the second workpiece (2) with regard to at least one property. [Step A]. At least the surfaces to be connected of the first, second and / or third workpiece (1, 2, 3) are cleaned and / or machined to remove the surface, for example during storage of the workpieces (1, 2, 3) to remove any rust layer that has formed and any other interfering particles on the surface [step B].

After cleaning and / or machining, the first, second and third workpiece (1, 2, 3) are stacked on top of one another or the second and third workpiece (2, 3) are positioned next to one another to form the core layer (II) [step C] to define the three layers (I, II, III) of the flat product package (10), the structure of the flat product package (10) being formed according to one of the preceding embodiments. Other designs are also possible.

After being stacked on top of one another, the individual layers (I, II; III) form a horizontal connecting plane (Vh) between them and are welded to one another at least in sections circumferentially to produce a flat product package (10). The layers (I, II; III) are preferably welded to one another completely circumferentially and in a gas-tight manner, in order to prevent an exchange or penetration of the furnace atmosphere when the flat product package (10) is subsequently heated between the layers (I, II, III) [ Step D].

The flat product package (10) is heated or heated through to at least one hot rolling start temperature, for example in a walking beam furnace at temperatures between 1100 and 1300 ° C., for example [step E].

After the minimum hot rolling start temperature has been reached, the flat product package (10) is rolled into a hot strip according to a specific pass schedule, which forms the hot-roll clad material composite [step F]. The corresponding layers (I, II, III) or workpieces (1, 2, 3) are completely cohesively connected to one another via the reference surface (s) (Ül, Ü2) and via the horizontal connection level (s) (Vh) .

The composite material or the hot strip can optionally be rolled into a calender strip, [step G] shown in dashed lines. The hot strip or optionally the cold strip is coated with an inorganic and / or organic coating, in particular with a metallic coating, preferably based on zinc or aluminum [step H]. After the coating is finished, the hot strip or, optionally, the cold strip is either cut to length into plates, sheets or sheets [step I] or coiled into a coil [step G] and made available to the processing industry.

The invention is not restricted to the exemplary embodiments shown in the drawing or to the explanations in the general description. Rather, the features of the invention can be combined with one another as desired, provided that it is technically possible. At least one of the workpieces (1, 2, 3) can for example consist of a steel material with a tensile strength> 600 MPa, in particular> 800 MPa, in particular also of a hardenable steel with tensile strengths of at least 1500 MPa in the hardened state, so that material composites can be provided which are press-hardenable and / or heat-treatable. Alternatively, materials can also be combined with one another in such a way that components with different properties can also be made available in the course of cold forming or warm forming.

Claims

1. Three-layer flat product package (10) with two outer layers (I, III) each consisting of a first workpiece (1) and a core layer (II) comprising at least one second workpiece (2, 3), the workpieces (1, 2, 3 ) are stacked on top of one another and define the three layers (I, II, III) of the flat product package (10), the workpieces (1, 2, 3) forming a horizontal connecting plane (Vh) between the layers (I; II; III) and are at least partially cohesively connected to one another, the flat product package (10) being intended for hot-roll cladding to produce a material composite, the flat product package (10) having a longitudinal extension (L) and a transverse extension (Q) and the longitudinal extension (L) is at least twice as long compared to the transverse stretching (Q),

characterized in that

the core layer (II) comprises at least one third workpiece (3) which differs from the first workpiece (1) and / or from the second workpiece (2) with regard to at least one property, the second workpiece (2) and the third workpiece (3) are positioned in the core layer (II) running alongside one another in the longitudinal direction, the second workpiece (2) and the third workpiece (3) forming a reference surface (Ül, Ü2) between them, which the workpieces (2, 3 ) separates from each other.

2. Flat product package according to claim 1, wherein two second workpieces (2) are provided, the second workpiece (2) and the third workpiece (3) being positioned in the core layer (II) in such a way that the second workpiece (2) is transverse (Q) in each case laterally and the third workpiece (3) is arranged within the core layer (II) between the respective second workpiece (2).

3. Flat product package according to claim 1 or 2, wherein the reference surface (Ül, Ü2) at an angle al = 0.1 ° to 90 °, in particular al = 5 ° to 80 ° and / or a2 = 90 ° to 179.9 ° , in particular special a2 = 100 ° to 175 ° to the transverse extent (Q) of the flat product package (10) is aligned, where al correspond to an acute angle and a2 to an obtuse angle.

4. Flat product package according to one of the preceding claims, wherein the workpieces (1, 2, 3) each consist of a steel with a first steel alloy (1), a second steel alloy (2) and a third steel alloy (3).

5. Flat product package according to claim 4, wherein the first steel alloy (1) has a carbon content of up to and including 0.1% by weight, the second steel alloy (2) has a carbon content of at least 0.15% by weight and the third steel alloy (3) has a carbon content which is at least 0.02% by weight higher than that of the second steel alloy (2).

6. A method for producing a composite material comprising the following steps:

Providing a flat product package (10) according to one of the preceding claims, heating the flat product package to at least one hot rolling start temperature, hot rolling the flat product package to form a hot strip,

Folding the hot strip into plates, sheets or sheets, or

Coiling the hot strip into a bundle.

7. The method according to claim 6, wherein the composite material is rolled into a cold strip and then flattened into sheets or reeled into a bundle.

8. The method according to any one of claims 6 or 7, wherein the composite material is coated with an inorganic and / or organic coating.

9. Use of a composite material produced according to one of claims 6 to 8 as a part or component in areas with wear influences, in mechanical engineering or plant construction, container construction, pipe construction, in the construction sector, in vehicle, rail and ship construction or in the aerospace industry.

10. Use according to claim 9, wherein the part or component is cold-formed, semi-hot-formed, press-hardened or tempered.