Method for producing an assembly molded part using a preconditioned foreign structure and assembly molded part

Abstract

Method for producing an assembly molded part (12') from a metallic molded blank (1) and a blank-like metallic foreign structure (2), characterized by the steps: • Applying an aluminum-containing coating to the mold plate (1), • Applying an aluminum-containing coating to the board-like metallic foreign structure (2), • Pretreatment of the platinum-like metallic foreign structure (2) by a thermal process in which the platinum-like metallic foreign structure (2) is brought into a pre-diffused state, subsequently • at least partial material-bonding application of the treated metallic foreign structure (2*) to a surface of the molded blank (1) and formation of an assembly part (12) and subsequently, • Hot forming the assembly part (12) so that the assembly molded part (12') is obtained after forming.

Description

[0001] The invention relates to a method for producing an assembly molded part from a molded blank and a blank-like foreign structure.

[0002] The use of foreign structures, also referred to as patch reinforcements in the hot forming of shaped components, especially sheet metal, offers the possibility of local sheet thickness adjustment, in particular increasing the sheet thickness for crash-relevant component areas in order to optimally adapt the component properties to the respective load case.

[0003] For example, B-pillars manufactured as formed sheet metal components are reinforced in the head area by the arrangement of foreign structures. In this case, a formed blank, as a precursor to the finished formed component, is locally reinforced with a foreign structure, in particular a patch, of the same type using spot welds and is then passed through a roller hearth furnace, in particular, to hot form the formed blank and form the formed component, where it is heated to, for example, 930°C [Celsius]. For example, patch reinforcement creates a thin sheet metal area starting from a sheet thickness of 1.5 mm without a patch, and a thicker sheet metal area of ​​1.5 mm plus 1.5 mm = 3.0 mm starting from a patch thickness (= material thickness of the foreign structure) of also 1.5 mm, with the thinner area adjacent to the thicker area.

[0004] A technical problem in the implementation arises with regard to the material used and its process window for the holding temperature after heating to a specified temperature. The material used to manufacture the molded component, 22MnB5, a manganese-boron alloyed heat-treatable steel, has an aluminum-containing coating that may contain small amounts of silicon and iron. This material system is known as Usibor® or MBW®-K1500 + AS.

[0005] The aluminum (silicon) coating, in particular, has a maximum furnace residence time, after which the heat-treatable steel in question becomes unweldable and its joining properties are also impaired. The reason for this is, among other things, the growth of the interdiffusion phase between the coating and the base material. The coating serves as an anti-scaling layer during heat treatment.

[0006] The thickened areas of the patch-reinforced blank heat up significantly more slowly than the unreinforced areas of the blank, which is why the use of patch reinforcements reduces the process window for the holding temperature after heating to a predefined temperature for the thinner sheet area. In other words, the maximum furnace residence time of the thinner sheet area is reached significantly before the thicker sheet area.

[0007] The explanations make it clear that the process limits of the blank provided with the foreign structure are narrowed with regard to the furnace residence time of the thinner sheet area and the furnace residence time of the thicker sheet area of ​​the blank after reaching a common holding temperature, as explained in more detail in the description, which leads to an increase in rejects and an overall reduction in process robustness after heating to the predefined holding temperature, for example in the event of irregularities in the process flow.

[0008] This means that a minimum heating time for the thicker area must be considered, which increases significantly for a local sheet thickness of 3.0 mm compared to a 1.5 mm thickness of a non-patch-reinforced monosheet. The resulting overall increase in furnace residence time correlates with the required but undesirable furnace lengths, or with an undesirable increase in cycle times in existing systems with short furnace lengths.

[0009] Depending on the patch size and / or the patch position on the blank, a relatively high number of welding spots are required to reinforce the blank prior to the hot forming step, which increases the unit costs of the blank.

[0010] In addition, uneven heating of the mold blanks leads to thermally induced distortion of the mold blank during heating, which causes downstream transport and / or handling problems.

[0011] Especially in existing furnace systems, restrictions exist, for example, in the form of roller spacing, furnace chamber heights, or gap spacing of the furnace inlet or outlet gate. During the manufacturing process, thermal distortion within the furnace system can lead to tilting or wedging of the mold blank with the foreign structure.

[0012] In summary, the problem is that cost-intensive blanks provided with the foreign structure do not meet the quality requirements in the previously explained hot forming step due to the narrow process limits and / or the roller hearth furnaces and the associated transport and / or transfer mechanisms of the blanks provided with the foreign structure have to be designed more complexly, which is disadvantageous.

[0013] The document DE 10 2008 027 460 A1 relates to a method for producing a hardened sheet steel component with areas of different ductility, wherein the behavior of the steel sheet during heating is changed in such a way that the heat absorption capacity of the steel sheet during heating for hardening is influenced depending on the desired degree of hardness, wherein good heat absorption behavior is realized for high degrees of hardness and reduced heat absorption behavior is realized for less hard areas and the microstructure is thereby made variable over the surface of the component or over the surface of the blank, wherein the adjustment of the microstructure and the adjustment of the heat absorption behavior are controlled via the surface emissivity.

[0014] Furthermore, the document DE 10 2015 102 908 A1 describes a method for producing a shaped part, in which a sheet metal is processed, wherein the sheet metal comprises a metal and forms a flat base body with a material thickness which is smaller in relation to the length dimensions of a surface of the sheet metal, wherein the sheet metal has a larger surface on an upper side and a lower side than on the surfaces determining the material thickness, wherein the following steps are carried out: firstly, materially bonding an external structure to a surface of the sheet metal and secondly, forming the sheet metal after applying the external structure, so that the shaped part is present after forming.

[0015] Reference is also made to the documents DE 10 2009 043 926 A1, DE 10 2008 006 771 B3, DE 10 2014 004 657 A1 and DE 101 62 415 A1 as well as US 2012 / 0 135 263 A1.

[0016] The document DE 10 2009 043 926 A1 describes a method for producing a motor vehicle component, in which a steel part is hot-formed and hardened at least in sections by contact with a tool surface, in which the steel part is cooled in at least two partial regions at different cooling rates during hardening, so that the partial regions differ in their microstructure after hardening. It is disclosed that the steel part is, in particular, a semi-finished product, in particular a tailored blank, a tailored-welded blank, a patchwork blank or a tailored-rolled blank, or a cut blank. A tailored blank is understood to be a sheet metal blank composed of different material grades and / or sheet thicknesses. In a tailored-welded blank, various sheet metal blanks are welded together.A tailored-rolled blank features different sheet thicknesses produced using a flexible rolling process. A patchwork blank consists of a single sheet onto which additional sheets are joined in a patch-like manner.

[0017] The document DE 10 2014 004 657 A1 additionally discloses a method for producing a component from a steel product coated with an Al-Si protective coating and an intermediate product which is produced in the course of such a method and can be used for the production of components of the type in question.In the course of the process, the steel product coated with the Al-Si coating is subjected to a first heating step in which the temperature and duration of the heat treatment are adjusted so that the Al-Si coating is only partially pre-alloyed with Fe of the steel product. In a second heating step, the steel product is heated to a heating temperature above the Ac1 temperature, at which temperature the steel product has an at least partially austenitic microstructure. The temperature and duration of the second heating step are adjusted so that the Al-Si coating is completely alloyed with Fe of the steel product during the second heating step. The steel product heated to the heating temperature is formed into the component and the resulting component is cooled in a controlled manner in order to produce a desired hardness microstructure.It is proposed that the process can also be used for steel products such as tailored blanks or patchwork blanks.

[0018] The invention is based on the object of modifying a molded blank reinforced with foreign structures in such a way that the robustness of the manufacturing process is increased, so that no molded blanks with material defects or even completely unusable molded blanks are produced within the process.

[0019] The starting point of the invention is therefore a method for producing an assembly molded part from a metallic molded blank and a blank-like metallic foreign structure with the steps: • Applying an aluminum-containing coating to the mold plate, • Applying an aluminum-containing coating to the board-like metallic foreign structure, • Pretreatment of the platinum-like metallic foreign structure by a thermal process in which the platinum-like metallic foreign structure is brought into a pre-diffused state, then • at least partial material-bonded application of the treated metallic foreign structure to a surface of the molded blank and formation of an assembly part and subsequently, • Hot forming of the assembly part so that after forming the assembly molded part is available.

[0020] According to the invention, it is thus provided that the metallic foreign structure is advantageously preconditioned by a pretreatment step before the at least partial material-bonded application to the surface of the molded blank in order to increase the degree of heat absorption compared to the molded blank.

[0021] A "foreign structure" is, in particular, a component made of a material that has a different spatial structure and / or properties than the preform blank. The foreign structure, in particular, has a different geometric shape, a different material, and / or a different design. However, the foreign structure can also be made of the same material as the preform blank. According to the invention, the foreign structure advantageously has an increased degree of heat absorption due to the preconditioning in one of the subsequent pretreatment steps, whereby the foreign structure heats up more quickly than the preform blank.

[0022] It is preferably provided that the metallic mold plate and the metallic foreign structure are made of a tempering steel.

[0023] In a preferred embodiment of the invention, the shaped blank and / or the metallic foreign structure are made of a manganese-boron alloyed tempering steel, which preferably has manganese contents of greater than / equal to 0.8 wt.% up to and including 12 wt.% and preferably boron contents of less than 0.5 wt.%.

[0024] An aluminum-containing coating is applied to the metallic foreign structure, which preferably has aluminum contents of greater than or equal to 80 wt.% and in particular iron contents of less than 10 wt.% and in particular silicon contents of less than 10 wt.%.

[0025] An aluminum-containing coating is applied to the molded blank, which contains aluminum contents of greater than / equal to (> / =) 80 wt.% and iron contents of less than ( < / =) 10 Gew.-% und Silizium-Anteile von kleiner (< / =) 10 Gew.-% aufweist.

[0026] It is preferably provided that the preformed blank and the metallic foreign structure are prefabricated from the same material or from different materials from the previously mentioned material spectrum. Thus, the preformed blank can also have an aluminum-containing coating within the specified spectrum.

[0027] According to the invention, the assembly part or a formed assembly molded part is characterized by a foreign structure preconditioned according to the method claims, as explained in more detail in the description.

[0028] The assembly part according to the invention or the assembly molded part formed according to the invention can be recognized by the fact that the metallic foreign structure has at least one changed surface quality compared to the molded blank as a result of the pretreatment step, in particular a more matt, non-reflective surface, whereby the heat absorption coefficient of the foreign structure is increased compared to the heat absorption coefficient of the molded blank.

[0029] Further differences between the assembly part according to the invention or the formed assembly part according to the invention and conventional assembly parts or assembly parts are explained in more detail in the description.

[0030] The invention is explained below with reference to the accompanying drawings. They show: Fig. 1 an external view of a cut-to-size blank with an applied foreign structure [patch]; Fig. 2 an external view of an assembly part of the cut-to-size blank with the foreign structure [patch] applied by means of a welding process; Fig. 3 which consists of the form board and the foreign structure [patch] according to Fig. 2 assembly molded part produced in one hot forming step; Fig. 4 a diagram of the furnace temperature T over the furnace residence time t to show the global process window during hot forming of the assembly part according to Fig. 2 to the assembly molded part according to Fig. 3 according to the state of the art; Fig. 5 a diagram of the furnace temperature T over time t to show the global process window during hot forming of the assembly part according to Fig. 2 to the assembly molded part according to Fig. 3 according to the invention.

[0031] Fig. 1 shows an external view of a cut metallic preformed board 1 with a metallic board-like foreign structure 2, a so-called patch, arranged but not yet joined to the preformed board 1.

[0032] It is clarified that the mold board 1 and the patch 2 are components manufactured separately in one prefabrication step each.

[0033] The exemplary blanks of the shaped blank 1 and the patch 2 represent the blanks for an exemplary side part of a roof section of a body of a motor vehicle, which is formed by a hot forming process, and in Fig. 3, whereby the viewer's view is directed to the inside of the formed component 12' in the installed state (compare Fig. 3) is directed.

[0034] The hot-formed component 12' is hereinafter referred to as the assembly molded part 12', while the component 12 not yet hot-formed is referred to as the assembly part 12, which comprises the described blanks 1, 2 (molded blank 1 and blank-like foreign structure 2).

[0035] How Fig. 2 in a further external view, the patch 2 is joined to the formed blank 1 before the hot forming process, wherein, for example, a welding process is used to join the formed blank 1 to the patch 2 to form the assembly part 12, in particular to weld them, as the welding points 3 in Fig. 2. It is understood that other joining methods can be used to produce an assembly part 12 according to Fig. 2 to produce.

[0036] Fig. 3 shows the patch-reinforced assembly molded part 12' produced from the assembly part 12 in the hot forming process in a further external view, which corresponds to the inside of the formed assembly molded part 12' in the installed state.

[0037] The known procedure thus comprises the steps of separately producing a molded blank 1 and a patch 2, joining the molded blank 1 and the patch 2 to form an assembly (molded blank / patch) part 12 and hot forming the assembly part 12 to produce the assembly molded part 12'.

[0038] The idea according to the invention is to ensure that the at least one thicker mold blank area 2A of the assembly part 12 provided with a patch 2 heats up faster than before during the furnace heating, so that the previously described process window of the predeterminable holding temperature increases after heating to the holding temperature during the hot forming of the assembly part 12 to the assembly molded part 12', as can be seen from the Fig. 4 and Fig. 5 will be explained later.

[0039] This means that, compared to the current procedure, the procedure according to the invention achieves a shorter time for generating the desired holding temperature in the thicker mold plate area 2A of the assembly part 12, so that the holding temperature is reached earlier.

[0040] A patch 2* of an assembly part 12 which has already been preconditioned according to the invention with a substantially aluminum-containing coating, wherein the aluminum-containing coating may contain small amounts of silicon and iron, heats up significantly faster in correlation with the emission factor compared to a conventional assembly part 12 in which the patch 2, which is also provided with an aluminum-containing coating, is not preconditioned.

[0041] In the following, the preconditioned foreign structure, in particular the patch, is identified by the reference symbol 2* to distinguish it from a conventional patch 2.

[0042] As preconditioning, it is provided that the patch 2* having the aluminum-containing coating is brought into a pre-diffused state prior to joining, in particular prior to the at least partial material-bonded application to the preform blank 1, independently of the preform blank 1. During preconditioning, the effect is advantageously achieved that, during heating of the assembly part 12, the highly reflective aluminum phases are reduced, whereby the temperature T over time t of the assembly part 12 rises more quickly than before during the heating process before the actual forming.

[0043] In other words, the heat absorption coefficient of the molded board area 2A* of the assembly part 12 provided with a preconditioned patch 2* becomes greater than that of the molded board area 2A of the assembly part 12 previously provided with a non-preconditioned patch 2.

[0044] The preconditioning of Patch 2* in detail: Patch 2 is brought into a pre-diffused state 2* by pre-diffusion. For this purpose, Patch 2 is subjected to a thermal process, either by batch annealing or a continuous thermal process similar to galvannealing for zinc. In the latter process, iron from the steel reacts with zinc, forming zinc-iron compounds. The melting point of the aluminum-containing coating (aluminum-(silicon) coating) is increased by iron enrichment, resulting in a typical gray, matte surface that heats up significantly faster because the highly reflective effect of the aluminum-containing coating is greatly reduced.

[0045] In the case of the assembly part 12, it can be seen with the naked eye before hot forming that the patch 2* or the patch-reinforced preconditioned thicker area 2A* has a changed, in particular a more matt surface than the thinner area 1A.

[0046] The diffusion process between iron and aluminum can be detected in the patch-reinforced preconditioned thicker region 2A* compared to the non-preconditioned thinner region 1A of the assembly part 12 by means of a metallographic examination.

[0047] In the case of the assembly molded part 12', the upstream diffusion process, after the hot forming has taken place, can also still be reliably detected by means of a metallographic examination.

[0048] In summary, the advantages of the method according to the invention: As a result, the preconditioning in the patch 2* itself and in relation to the adjacent thinner areas 1A as well as the areas below the patch 2* leads, through a changed heat conduction within the preconditioned patch 2*, firstly to a significantly more homogeneous heating pattern of the mold blank 1 and the patch 2*, in particular in the mold blank 1 below the patch 2*, whereby secondly an acceleration of the heating of the patch 2* until the holding temperature is reached and thirdly an enlargement of the process window of the specified holding temperature after heating to the holding temperature is effected, and fourthly less distortion occurs during hot forming, thereby achieving an overall increase in process reliability.

[0049] Other previous processing properties of the assembly molded part 12' are advantageously not influenced by the preconditioning of the patch 2*.

[0050] The hot forming process of the assembly part 12 according to the invention only needs to be adapted compared to the previous procedure in such a way that a partial acceleration of the heating rate in the patch 2*, in particular in the preconditioned thicker region 2A* of the assembly part 12, is now taken into account.

[0051] The pretreatment step results in the adjustment of the heating rate between the preconditioned thick and thin regions 2A*, 1A of the assembly part 12 or between the preconditioned patched (thicker) region 2A* and the non-patched (thinner) region 1A of the assembly part 12, thereby creating greater dimensional stability of the formed assembly parts 12' and a significantly more robust process.

[0052] The reduction or approximation of the different heating rates between the preconditioned patched and the non-patched areas 2A*, 1A advantageously enables the realization of larger thickness differences between the preconditioned patched and the non-patched areas 2A*, 1A of the assembly part 12.

[0053] In addition, the process window of the holding temperature after heating to a predefined temperature is significantly increased for non-patched and preconditioned patched areas 1A, 2*.

[0054] In addition, not only is the process window of the holding temperature increased after heating to a predeterminable temperature, but the minimum furnace residence time is also reduced, since the preconditioned patch 2* or the preconditioned patched area 2A*, which specifies the minimum furnace residence time, heats up more quickly.

[0055] The Fig. 4 and Fig. 5 show the advantages of the invention with regard to the enlargement of the process window of the holding temperature after heating the assembly part 12 to a predeterminable furnace temperature TOven in [°C] over the furnace residence time t in [min].

[0056] In Fig. 4 shows a diagram of the furnace temperature TOn versus the furnace residence time t of the hot forming process for non-patched and patched areas 1A, 2A according to the state of the art.

[0057] The unpatched area 1A is assigned a process window P-1A, which is shown with a dashed line.

[0058] The patched area 2A is assigned a process window P-2A, which is shown with a solid line.

[0059] The two process windows P1-A and P-2A overlap depending on the furnace temperature TOven and form an overlap area Ü.

[0060] The overlap area Ü of both areas 1A, 2A, which forms the global time window depending on the respective holding temperatures T over the furnace residence time t, is shown cross-hatched.

[0061] The previous small overlap time Ü (Ü = tmax1A - tmin2A) is at the example selected furnace temperature TOven = 930°C by the maximum furnace throughput time tmax1A (compare Fig. 4) of the unpatched area 1A and by the minimum furnace throughput time tmin2A (compare Fig. 4) of the non-preconditioned patched area 2A* of the assembly part 12.

[0062] In Fig. 5 shows the hot forming process for non-patched and patched areas 1A, 2A* based on the diagram of the furnace temperature TOn versus the furnace residence time t, which results when the assembly part 12 has the preconditioned patch 2* or the preconditioned patched area 2A* according to the invention.

[0063] The process window P-2A* of the preconditioned patched area 2A*, which is shown as a dash-dot line, shifts in Fig. 5 opposite the process window P-2A in Fig. 4 to the left.

[0064] The defined overlap time Ü* (Ü* = tmax1A - tmin2A*) between the maximum furnace throughput time tmax1A of the unpatched area 1A and the minimum furnace throughput time tmin2A* of the patched area 2A* of the assembly part 12 preconditioned according to the invention is at each and thus also the exemplary selected furnace temperature of TOfen = 930°C compared to Fig. 4 larger (Ü < Ü*).

[0065] The cross-hatching illustrates that the overlap area Ü* and thus the global process window as a whole increases, so that the available maximum furnace throughput time tmax2A* for the thicker preconditioned sheet area 2A* is less restricted within the maximum furnace throughput time Δtmax1A of the unpatched area 1A.

[0066] In other words, at the respective holding temperature within the global process window, a longer overlapping time period Ü* is available by increasing the overlap area Ü.

[0067] The relatively short overlap period Ü available so far (compare Fig. 4) the holding temperature after heating the assembly part 12 to the preset temperature TOven = 930°C (compare Fig.5) and is now U*, which leads to a reduction in scrap in the event of irregularities in the process flow and thus to an overall increase in process robustness. List of reference symbols 1 mold board 2 Foreign structure (patch) (state of the art) 2* preconditioned foreign structure (patch) 1A thin area of ​​the mold board 1 2A thick area of ​​the mold board 1 with foreign structure (patch) 2A* thick area of ​​the mold board 1 with the preconditioned foreign structure (patch) 3 welding points 12 Assembly part (after joining and before hot forming) 12' assembly molded part (after hot forming) Oven Oven temperature T Temperature of the assembly part t time P-1A ​​Process window of the thin area 1A (dashed line) P-2A process window of the thick patched area 1A according to the state of the art (solid line) P-2A* Process window of the thick (patched) preconditioned area 1A according to the invention (dash-dotted line) tmin1A Minimum furnace throughput time of the thin area 1A tmax1A Maximum furnace throughput time of the thin area 1A tmin2A Minimum furnace throughput time of the thick (patched) area 2A according to the state of the art tmax2A Maximum furnace throughput time of the thick (patched) area 2A according to the state of the art tmin2A* Minimum furnace throughput time of the thick (patched) preconditioned area 2A according to the invention tmax2A* Maximum furnace throughput time of the thick (patched) preconditioned area 2A according to the invention Ü temporal overlap range according to the state of the art Ü* temporal overlap area according to the invention

Claims

[1] Method for producing an assembly molded part (12') from a metallic mold blank (1) and a blank-like metallic foreign structure (2) characterized by the steps: • Applying an aluminium-containing coating to the mold plate (1), • Applying an aluminium-containing coating to the circuit board-like metallic foreign structure (2), • Pretreatment of the circuit board-like metallic foreign structure (2) by a thermal process in which the circuit board-like metallic foreign structure (2) is brought into a pre-diffused state, subsequently • at least partial material bonding of the treated metallic foreign structure (2*) onto a surface of the mold plate (1) and formation of an assembly part (12) and subsequently, • Hot forming of the assembly part (12) so that after forming the assembly molded part (12') is obtained. [2] Method according to claim 1, characterized by , that the metallic form plate (1) and the metallic foreign structure (2) are made of a heat-treated steel. [3] Method according to claim 2, characterized by , that the mold plate (1) and / or the metallic foreign structure (2) are made of a manganese-boron alloyed heat-treatable steel, which in particular contains manganese content of greater than or equal to (> / =) 0.8 wt.% up to and including ( < / =) 12 Gew.-% und Bor-Anteile kleiner (< / =) 0,5 Gew.-% aufweist. [4] Method according to claim 1, characterized by , that the aluminium-containing coating applied to the mold plate (1) contains aluminium proportions greater than or equal to (> / =) 80 wt.% and iron proportions of less than ( < / =) 10 Gew.-% und Silizium-Anteile von kleiner (< / =) 10 Gew.-% aufweist . [5] Method according to claim 1, characterized by, that the aluminium-containing coating applied to the metallic foreign structure (2) contains aluminium content of greater than or equal to (> / =) 80 wt.% and iron content of less than ( < / =) 10 Gew.-% und Silizium-Anteile von kleiner (< / =) 10 Gew.-% aufweist. [6] Method according to claim 1, characterized by , that the form plate (1) and the metallic foreign structure (2) are prefabricated from the same material or from different materials of the material spectrum according to claim 3. [7] Assembly molded part (12') comprising a metallic molded sheet (1) and a sheet-like metallic foreign structure (2), • wherein the form sheet (1) and the sheet-like metallic foreign structure (2) have an aluminium-containing coating, and • the metallically treated foreign structure (2*) is preconditioned in a pretreatment step by a thermal process to a pre-diffused state, and • the metallically treated foreign structure (2*) is arranged by at least partial material bonding onto a surface of the mold plate (1) to form an assembly part (12), and • the assembly part (12) is formed into the assembly molded part (12') by hot forming. [8] Assembly molded part (12') according to claim 7, characterized by , that the treated foreign structure (2*) has at least a changed surface texture compared to the mold plate (1), in the form of a changed heat emission behavior due to a more matte non-reflective surface, whereby the heat absorption coefficient of the foreign structure (2) is increased compared to the heat absorption coefficient of the mold plate (1). [9] Assembly molded part (12') according to claim 7, characterized by, that the mold plate (1) and / or the metallic foreign structure (2) are made of a manganese-boron alloyed heat-treatable steel containing manganese content greater than or equal to 0.8 wt.% up to and including ( < / =) 12 Gew.-% und Bor-Anteile kleiner (< / =) 0,5 Gew.-% aufweist. [10] Assembly molded part (12') according to claim 7, characterized by , that the aluminium-containing coating of the metallic form sheet (1) and the sheet-like metallic foreign structure (2) contains aluminium content of greater than or equal to (> / =) 80 wt.% and iron content of less than ( <!--=) 10 Gew.-% und Silizium-Anteile von kleiner (< / =) 10 Gew.-% aufweist.-->

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