Process for producing an aluminum pressure casting alloy having a secondary aluminum content, an aluminum pressure casting alloy having a secondary aluminum content and a structural component for a motor vehicle
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-14
- Publication Date
- 2026-04-08
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Abstract
Description
[0001] Method for producing an aluminum die-casting alloy with secondary aluminum content, aluminum die-casting alloy with secondary aluminum content and structural component for a motor vehicle
[0002] DESCRIPTION:
[0003] The invention relates to a method for producing an aluminum die-casting alloy with a secondary aluminum content, which, in addition to aluminum, contains silicon, iron, manganese, and magnesium as alloying constituents. The invention further relates to an aluminum die-casting alloy with a secondary aluminum content and a structural component for a motor vehicle.
[0004] From the prior art, for example, the document EP 2 657 360 A1 is known. This describes an AISi-based die-casting alloy, comprising in particular secondary aluminum, wherein the die-casting alloy comprises 6 to 12 wt.% silicon (Si), at least 0.3 wt.% iron (Fe), at least 0.25 wt.% manganese (Mn), at least 1 wt.% copper (Cu), 0.24 to 0.8 wt.% magnesium (Mg) and 0.4 to 1.5 wt.% zinc (Zn), wherein the total proportion of Fe and Mn in the die-casting alloy together is a maximum of 1.5 wt.%, the quotient of the weight percentages of Fe and Mn is 0.35 to 1.5 and the quotient of the weight percentages of Cu and Mg is 0.2 to 0.8.
[0005] Furthermore, WO 2020 / 207708 A1 discloses an aluminum die-casting alloy with the following alloying constituents: 7.5 to 11.5 wt.% silicon, 0.25 to 0.6 wt.% manganese, 0.03 to 0.06 wt.% chromium, less than 0.05 wt.% molybdenum, as well as aluminum and unavoidable impurities. The object of the invention is to propose a method for producing an aluminum die-casting alloy with a secondary aluminum content, which has advantages over known methods, in particular enabling the production of a naturally hard die-casting alloy despite the use of a large secondary aluminum content.
[0006] This is achieved according to the invention with a method for producing an aluminum die-casting alloy with a secondary aluminum content with the features of claim 1. It is provided that, depending on a magnesium content of the die-casting alloy, a proportion of at least one component of the die-casting alloy is adjusted such that a magnesium-containing primary phase, in particular a magnesium-containing, temperature-stable primary phase, is formed upon cooling of the die-casting alloy.
[0007] Advantageous embodiments with useful further developments of the invention are specified in the dependent claims. It should be noted that the exemplary embodiments explained in the description are not limiting; rather, any variations of the features disclosed in the description, the claims, and the figures are feasible.
[0008] The process is used to produce the aluminum die-casting alloy based on secondary aluminum, i.e., recycled aluminum. The recycled aluminum is obtained, for example, from aluminum scrap, so that the energy-intensive preparation of primary aluminum can be partially dispensed with. However, the secondary aluminum content means that the die-casting alloy ultimately contains impurity elements that are not necessary for achieving the desired properties of the die-casting alloy, but can actually counteract them. The impurity elements cannot be prevented, or at least only to a limited extent, by the recycling process and are therefore present in the starting material on which the aluminum die-casting alloy is based. For example, the proportions of iron and / or magnesium are increased. The starting material can also contain copper and / or zinc.While iron, copper (at least in typical copper proportions, especially those mentioned in this description), and zinc only affect the ductility and corrosion resistance of the die-casting alloy, magnesium makes the die-casting alloy hardenable, so that a naturally hard alloy cannot be achieved. To achieve a naturally hard die-casting alloy using conventional methods, its magnesium content must not exceed 0.08 wt.% to prevent hardening of the die-casting alloy, especially during its production.
[0009] However, the starting material can contain a significantly higher proportion of magnesium, particularly if the proportion of secondary aluminum in the die-casting alloy is to be at least 50% or more. This results in a magnesium content of more than 0.08 wt.%, in particular a magnesium content of at least 0.10 wt.%, at least 0.20 wt.%, at least 0.30 wt.% or at least 0.40 wt.%. If the die-casting alloy is to be naturally hard, the magnesium must be removed from it using suitable processes in conventional methods, for example by salting, chlorination or the like. These processes not only increase the cost of the die-casting alloy, they also increase energy consumption and may lead to the production of environmentally harmful and / or hazardous products.
[0010] If such processes are to be avoided, the magnesium content of the die-casting alloy must be adjusted by adding appropriate amounts of primary aluminum so that its magnesium content is suitable for a naturally hard die-casting alloy. The limit for the magnesium content of 0.08 wt.% and the usual magnesium content of the secondary aluminum result in a maximum proportion of secondary aluminum in the die-casting alloy of 30%. Wherever reference is made to a content or proportion of a substance in the alloy within the scope of this description, the terms are used interchangeably. Both terms refer to a weight proportion, which is expressed as a weight percent (wt.%).
[0011] In order to avoid both the aforementioned processes for removing magnesium from the die-casting alloy and the excessive addition of primary aluminum, the magnesium is prevented from hardening by a clever composition of the die-casting alloy. To this end, the proportion of at least one component of the die-casting alloy is adjusted such that the magnesium-containing primary phase forms upon cooling of the die-casting alloy, thus making the die-casting alloy naturally hard. This means that the magnesium is bound in the primary phase and remains insoluble or only partially dissolved upon cooling of the die-casting alloy.
[0012] The thus bound magnesium is no longer available for the hardening of the die-casting alloy, as it is bound in the primary phase, particularly the temperature-stable primary phase. Despite the presence of magnesium in the die-casting alloy, its hardening can be prevented at least partially or even completely, so that the die-casting alloy is naturally hard. In other words, the composition of the die-casting alloy should be selected such that the magnesium is deliberately bound in the primary phase to prevent its participation in subsequent hardening due to heat exposure, particularly its participation with the formation of a Mg2Si secondary phase. The primary phase is particularly temperature-stable or thermally stable.
[0013] The aforementioned hardening occurs, for example, due to the heat present in the melt and / or after cooling of the component made from the die-cast alloy due to the heat applied to it. The heat applied may occur, for example, due to a manufacturing step following casting, such as during the drying of a paint coating. However, it can also be due to the ambient conditions of the component. In the manner described, it is always possible to achieve a naturally hard die-cast alloy, even with a high proportion of secondary aluminum.
[0014] A further development of the invention provides that the aluminum die-casting alloy, in order to achieve the secondary aluminum content, is produced from a starting material containing secondary aluminum, which has at least 0.08 wt.% magnesium, in particular more than 0.08 wt.% magnesium. The aluminum die-casting alloy is based on the starting material containing the secondary aluminum. The aluminum die-casting alloy can therefore also be referred to as a secondary aluminum die-casting alloy. It can be provided that the die-casting alloy consists exclusively of the starting material containing the secondary aluminum. For example, the starting material consists entirely or substantially of secondary aluminum, so that the starting material as a whole has a comparatively high magnesium content, namely at least 0.08 wt.%.
[0015] In order to facilitate the provision of the starting material, a significantly higher magnesium content is preferably permitted. The magnesium content of the starting material is preferably at least 0.10 wt.%, at least 0.12 wt.% or at least 0.15 wt.%. However, the magnesium content can also be even higher and is, for example, at least 0.20 wt.%, at least 0.25 wt.% or at least 0.30 wt. Additionally or alternatively, the magnesium content is at most 0.50 wt.%, at most 0.45 wt.% or at most 0.40 wt. With the described magnesium content, on the one hand, the good availability of the starting material is ensured even without energy-intensive processes and, on the other hand, the naturally hard aluminum die-casting alloy is provided in the manner described despite the high magnesium content.
[0016] A further development of the invention provides that the proportion of secondary aluminum in the die-casting alloy is at least 50%. The die-casting alloy comprises the secondary aluminum and is adjusted to the described composition, in particular by the addition of primary aluminum and / or one or more of the alloy components. In any case, the proportion of secondary aluminum in the die-casting alloy is significantly higher than in known processes for producing naturally hard die-casting alloys and is at least 50%. However, it is preferably higher, in particular it is at least 60%, at least 70% or at least 80%, so that the magnesium content of the die-casting alloy is correspondingly comparatively high. Nevertheless, the naturally hard die-casting alloy is achieved using the described procedure.The disadvantageous removal of magnesium from the die-casting alloy or the starting material can be avoided, so that the die-casting alloy is provided in a sustainable manner.
[0017] A further development of the invention provides for manganese to be used as the at least one component. Manganese is added to a conventional die-casting alloy to improve its demoldability, i.e., the removal of a component produced using the die-casting alloy from a casting mold. In particular, the manganese reduces the die-casting alloy's tendency to stick. If the die-casting alloy's tendency to stick is too high, for example, due to a low manganese content, the component can no longer be demolded from the casting mold, especially if it is structurally complex.
[0018] On the one hand, poor demoldability is disruptive to the manufacturing process. On the other hand, the increased tendency to stick affects the dimensional stability of the component and also causes increased wear of the casting mold and / or any casting tool containing the casting mold. On the other hand, an excessively high manganese content leads to coarse intermetallic precipitates, which cause embrittlement of the die-casting alloy and consequently reduce its ductility and formability of the component. In known die-casting alloys, the manganese content is therefore between 0.3 and 0.8 wt.%. As the die-casting alloy cools, the manganese forms an intermetallic primary phase with iron, the so-called Al(Fe,Mn)Si phase, also known as the AlFeSi phase. In addition to the manganese, aluminum, iron, and silicon are thus bound.The magnesium contained in the die-casting alloy, however, remains in solution during cooling and thus forms the basis for the subsequent hardening of the die-casting alloy. For this reason, the manganese content of the die-casting alloy should be reduced to reduce or even completely prevent the formation of the Al(Fe,Mn)Si phase.
[0019] Instead, an rr primary phase is formed, which exists as a quaternary primary phase and is composed of aluminum, iron, magnesium, and silicon. The rr primary phase exists primarily as the TT-AI8FeMg3Si6 phase. The rr primary phase therefore absorbs magnesium and binds it in the primary phase. The magnesium bound in this way is no longer available for hardening the die-casting alloy because it is bound in the stable phase, particularly the thermally stable phase. The formation of the rr primary phase instead of the Al(FemMn)Si primary phase using iron is favored by the use of chromium and / or molybdenum instead of manganese. Unlike manganese, chromium and molybdenum bind little or no iron, so that at a later point in time during the cooling of the alloy melt, sufficient iron is still available to form the rr primary phase.Despite the presence of magnesium in the die-casting alloy, its hardening can therefore be prevented and consequently a naturally hard version of the alloy can be achieved.
[0020] A further development of the invention provides that the at least one component is substituted by at least one substitution component, wherein chromium and / or molybdenum is used as the at least one substitution component. It has already been explained that manganese improves the demoldability of the component produced from the die-cast alloy. However, to reduce or prevent the formation of the Al(Fe,Mn)Si phase, the manganese content must be reduced. To ensure the demoldability of the component, chromium or molybdenum is used instead of manganese.
[0021] For example, a chromium content of at least 0.06 wt.%, at least 0.08 wt.%, at least 0.1 wt.% or at least 0.3 wt.% is used. Additionally or alternatively, the chromium content is at most 0.6 wt.%, at most 0.5 wt.% or at most 0.4 wt.%. Preferably, the chromium content is at least 0.1 wt.% and at most 0.5 wt.%, at most 0.4 wt.% or at most 0.3 wt.%. Additionally or alternatively, the die-casting alloy comprises molybdenum, preferably in a proportion of at least 0.001 wt.% to at most 0.3 wt.%. Particularly preferably, the molybdenum proportion is at least 0.01 wt.% or at least 0.1 wt.% on the one hand and at most 0.3 wt.% or at most 0.2 wt.% on the other.
[0022] The above-mentioned proportions of chromium and / or molybdenum ensure the desired demoldability of the die-casting alloy. An additional advantage of the chromium content in the die-casting alloy is its increased ductility compared to an alloy with the same manganese content.
[0023] A further development of the invention provides for the use of an rr-AlFeMgSi phase, in particular a TT-Al8FeMg3Si6 phase, as the magnesium-containing primary phase. This has already been discussed above. Said primary phase binds the magnesium, so that it is no longer available for hardening the die-casting alloy. This achieves the aforementioned advantages.
[0024] A further development of the invention provides that the total proportion of chromium and / or molybdenum in the die-casting alloy is selected to be at least equal to the total proportion of manganese in the die-casting alloy, in particular greater. In other words, the total chromium and molybdenum content of the die-casting alloy are greater than its manganese content. The chromium or molybdenum content can be zero, so that either the chromium or molybdenum content is at least equal to the manganese content.
[0025] Preferably, the proportion of chromium and / or molybdenum in the die-casting alloy is, in total, greater by a factor of at least two, at least four, or at least six than the manganese content of the die-casting alloy. Further preferably—in particular regardless of the ratio between the proportion of chromium and / or molybdenum in the die-casting alloy and the chromium content of the die-casting alloy—the chromium content of the die-casting alloy is greater than the molybdenum content, in particular by a factor of at least two, at least three, or at least four.
[0026] Particularly preferably, the die-casting alloy contains both chromium and molybdenum, wherein the sum of the chromium and molybdenum content of the die-casting alloy corresponds at least to the manganese content of the die-casting alloy, in particular by a factor of at least two, at least four, or at least six. In addition, the chromium content of the die-casting alloy is greater than its molybdenum content, in particular by a factor of at least two, at least three, or at least four. The advantages already explained are achieved in the manner described.
[0027] A further development of the invention provides that the die-casting alloy is produced with the following composition: 6.5 to 11.5 wt.% silicon (Si), at most 0.25 wt.% manganese (Mn), 0.06 to 0.6 wt.% chromium (Cr), 0.05 to 0.5 wt.% magnesium (Mg), 0.05 to 0.4 wt.% iron (Fe), optionally 0.001 to 0.3 wt.% molybdenum (Mo), optionally 0.004 to 0.2 wt.% titanium (Ti), optionally 0.01 to 0.2 wt.% zirconium (Zr), optionally 0.008 to 0.02 wt.% strontium (Sr), optionally 0.001 to 0.1 wt.% vanadium (Va), optionally 0.001 to 0.5 wt.% copper (Cu), optionally 0.001 to 0.6 wt.% zinc (Zn), and the remainder Aluminum and unavoidable impurities. The die-casting alloy contains aluminum and at least the non-optional elements in the stated proportions as alloying components; in particular, it consists exclusively of these. In addition, the die-casting alloy may contain one or more of the optional elements.It also contains unavoidable impurities, preferably in the smallest possible proportion. The proportion of aluminum and impurities in the die-casting alloy is at least 84.83 wt.%, preferably more. Unavoidable impurities are elements that are usually present together with the alloying constituents of the die-casting alloy and cannot be easily separated from them or can only be separated with considerable effort.
[0028] The proportion of unavoidable impurities in the die-casting alloy is preferably at most 1 wt.%, at most 0.5 wt.%, or at most 0.1 wt.%. The proportion of impurities, or the proportion of each of the impurities, is preferably at most 0.5 wt.%, at most 0.25 wt.%, or at most 0.1 wt.%. The statement of at most 0.25 wt.% manganese is to be understood as meaning that ideally the manganese proportion is as low as possible, so that the die-casting alloy is preferably manganese-free. However, it can be provided that a low manganese proportion is present, in particular at least 0.001 wt.%, so that the total amount is at least 0.001 wt.% to at most 0.25 wt.%. With such a composition of the die-casting alloy, the advantages already explained are achieved.
[0029] The invention further relates to an aluminum die-casting alloy with a secondary aluminum content, in particular produced according to the method according to the statements in the context of this description. This is characterized by the following alloy components: 6.5 to 11.5 wt% silicon (Si), maximum 0.25 wt% manganese (Mn), 0.06 to 0.6 wt% chromium (Cr), 0.05 to 0.5 wt% magnesium (Mg), 0.05 to 0.4 wt% iron (Fe), optionally 0.001 to 0.3 wt% molybdenum (Mo), optionally 0.004 to 0.2 wt% titanium (Ti), optionally 0.01 to 0.2 wt% zirconium (Zr), optionally 0.008 to 0.02 wt% strontium (Sr), optionally 0.001 to 0.1 wt% vanadium (Va), optionally 0.001 to 0.5 wt% copper (Cu), optionally 0.001 to 0.6 wt% zinc (Zn), and the remainder aluminum and unavoidable Contamination.
[0030] The advantages of such a composition of the aluminum die-casting alloy and the process for its production have already been discussed. Both the aluminum die-casting alloy and the process for its production can be further developed according to the explanations in this description, so reference is made to these in this regard.
[0031] The silicon content of 6.5 to 11.5 wt.% present in the die-casting alloy ensures sufficient strength and good mold filling properties. The silicon also counteracts the formation of solidification cavities during cooling of the die-casting alloy.
[0032] Manganese affects the demoldability of the die-casting alloy. It can also result in high ductility. As already explained, the manganese content of the die-casting alloy should be low, and the manganese should be substituted with chromium and / or molybdenum. A manganese content of no more than 0.25 wt.%, no more than 0.2 wt.%, or no more than 0.15 wt.% is preferred. In this respect, manganese can be completely omitted from the die-casting alloy, so that the die-casting alloy is manganese-free, or the manganese is only present as unavoidable impurities. For example, the manganese content is at least 0.001 wt.% and corresponds to at most one of the values already mentioned. This achieves the advantages explained.
[0033] The chromium content of the die-casting alloy ensures its demoldability despite the low manganese content. For this purpose, the chromium content is at least 0.06 wt.%, preferably more than 0.06 wt.%. For example, it is at least 0.08 wt.%, at least 0.1 wt.%, or at least 0.3 wt.%. Preferably, it is at most 0.6 wt.%, at most 0.5 wt.%, or at most 0.3 wt.%. A chromium content of 0.1 wt.% to 0.5 wt.% or up to 0.3 wt.% is particularly preferred. The chromium ensures demoldability and increased ductility.
[0034] In addition to aluminum and unavoidable impurities, the aluminum die-casting alloy preferably consists of the following alloy components:
[0035] - Silicon: 6.5 wt% to 11.5 wt%, preferably at least 6.5 wt% as a lower limit and at most 11.5 wt% as an upper limit;
[0036] - Manganese: not more than 0.25% by weight, preferably optionally at least 0.001% by weight as a lower limit and not more than 0.25% by weight, not more than 0.2% by weight or not more than 0.15% by weight as a mandatory upper limit;
[0037] - Chromium: 0.06 wt% to 0.6 wt%, preferably as a lower limit at least 0.06 wt%, at least 0.08 wt%, at least 0.1 wt% or at least 0.3 wt% and as an upper limit at most 0.6 wt%, at most 0.5 wt% or at most 0.3 wt%;
[0038] - Magnesium: 0.05 wt% to 0.5 wt%, preferably as a lower limit at least 0.05 wt%, at least 0.08 wt%, at least 0.1 wt%, at least 0.12 wt% or at least 0.15 wt% and as an upper limit at most 0.5 wt% or at most 0.4 wt%,
[0039] - Iron: 0.05 wt% to 0.4 wt%, preferably at least 0.05 wt%, at least 0.15 wt%, at least 0.18 wt% or at least 0.22 wt% as a lower limit and at most 0.4 wt% or at most 0.3 wt% as an upper limit.
[0040] Optionally, one or more of the following alloy components are part of the die-casting alloy:
[0041] - Molybdenum: 0.001 wt% to 0.3 wt%,
[0042] - Titanium: 0.004 wt% to 0.2 wt%,
[0043] - Zirconium: 0.01 wt% to 0.2 wt%, - Strontium: 0.008 wt% to 0.02 wt%,
[0044] - Vanadium: 0.001 wt% to 0.1 wt%,
[0045] - copper: as a lower limit at least 0.001 wt%, at least 0.03 wt%, at least 0.05 wt% and as an upper limit at most 0.5 wt%,
[0046] - Zinc: as a lower limit at least 0.001 wt%, at least 0.03 wt%, at least 0.05 wt% and as an upper limit at most 0.6 wt%.
[0047] Preferably, the die-casting alloy in the described composition comprises more than 6.5 wt.% silicon, more than 0.06 wt.% chromium, more than 0.08 wt.% magnesium, 0.05 to 0.4 wt.% iron.
[0048] In a preferred first variant, the aluminum die-casting alloy comprises, in addition to aluminum and unavoidable impurities, the following alloy components:
[0049] - silicon: as a lower limit at least 6.5 wt% and as an upper limit at most 11.5 wt%;
[0050] - Manganese: optionally as a lower limit at least 0.001 wt% and as a mandatory upper limit not more than 0.2 wt% or not more than 0.15 wt%;
[0051] - Chromium: as a lower limit, at least 0.06% by weight, at least 0.08% by weight, at least 0.1% by weight or at least 0.3% by weight and as an upper limit, at most 0.6% by weight, at most 0.5% by weight or at most 0.3% by weight;
[0052] - magnesium: as a lower limit, at least 0.1% by weight, at least 0.15% by weight or at least 0.20% by weight and as an upper limit, at most 0.5% by weight or at most 0.4% by weight;
[0053] - iron: as a lower limit, at least 0.15% by weight or at least 0.20% by weight and as an upper limit, at most 0.4% by weight or at most 0.3% by weight;
[0054] - optionally: one or more of the optional alloying components. In a particularly preferred second variant, the aluminum die-casting alloy contains the following alloying components in addition to aluminum and unavoidable impurities:
[0055] - silicon: as a lower limit at least 6.5 wt% and as an upper limit at most 11.5 wt%;
[0056] - Manganese: optionally as a lower limit at least 0.001 wt% and as a mandatory upper limit not more than 0.2 wt% or not more than 0.15 wt%;
[0057] - Chromium: as a lower limit, at least 0.06% by weight, at least 0.08% by weight, at least 0.1% by weight or at least 0.3% by weight and as an upper limit, at most 0.6% by weight, at most 0.5% by weight or at most 0.3% by weight;
[0058] - magnesium: as a lower limit, at least 0.25% by weight or at least 0.30% by weight and as an upper limit, at most 0.5% by weight or at most 0.4% by weight;
[0059] - iron: as a lower limit, at least 0.15% by weight or at least 0.20% by weight and as an upper limit, at most 0.4% by weight or at most 0.3% by weight;
[0060] - optional: one or more of the optional alloying components.
[0061] In a third variant, which is also advantageous, the aluminum die-casting alloy contains the following alloy components in addition to aluminum and unavoidable impurities:
[0062] - Silicon: 6.5 wt% to 11.5 wt%;
[0063] - Manganese: 0.001 wt% to 0.15 wt%;
[0064] - Chromium: 0.1 wt% to 0.3 wt%;
[0065] - Magnesium: 0.25 wt% to 0.5 wt%;
[0066] - Iron: 0.15 wt% to 0.4 wt%;
[0067] - optional: one or more of the optional alloying components.
[0068] Preferably, in each of the variants, the sum of the proportion of chromium and the proportion of molybdenum (if present) corresponds at least to the proportion of manganese, in particular the sum is greater than the manganese proportion, preferably by a factor of at least two, at least four or at least six.
[0069] The invention also relates to a structural component for a motor vehicle, made from an aluminum die-cast alloy according to this description. The advantages and possible advantageous developments have already been pointed out, so reference is made to the corresponding statements in this description. Furthermore, the invention relates to the use of the aluminum die-cast alloy according to this description for producing a structural component for a motor vehicle.
[0070] The structural component can be used for a variety of purposes. For example, it is used for a body element, in particular a cover plate and / or a support. However, the structural component can also be used as a battery housing, engine housing, or the like.
[0071] The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed by the invention that are not explicitly shown or explained in the description and / or the figures, but which follow from or can be derived from the explained embodiments.
[0072] The material properties of the described die-casting alloy were determined through tests. For this purpose, components were produced from two different die-casting alloys that have the same magnesium content but differ in terms of manganese and chromium content. One of the die-casting alloys is a comparison alloy in the form of the alloy AISi7MnO,6MgO,2. Another of the die-casting alloys is the alloy according to the invention AISi7CrO,3MgO,2. The designations clearly indicate that the alloys contain identical amounts of silicon and magnesium. The comparison alloy has 0.6 wt.% manganese, whereas the manganese content of the alloy according to the invention is less than 0.2 wt.%. In contrast, the comparison alloy contains less than 0.2 wt.% chromium, while the alloy according to the invention contains 0.3 wt.%.
[0073] The material properties of both alloys were determined, firstly, after a component was cast and, secondly, after heat treatment of the respective component. Several components were manufactured from each alloy, with only one component from each alloy being subjected to heat treatment. The material properties of the components and alloys after casting and before heat treatment are summarized in the following table, with the comparison alloy listed as Alloy No. 1 and the alloy according to the invention as Alloy No. 2:
[0074] Alloy R P o,2 [MPa] Rm [MPa] A g [%] A [%]
[0075] No. 1 109 262 12 13
[0076] No. 2 105 258 13 15
[0077] The following are the material properties of the components or alloys after heat treatment, as occurs, for example, when a paint finish dries:
[0078] Alloy R P o,2 [MPa] Rm [MPa] A g [%] A [%]
[0079] No. 1 146 274 9 10
[0080] No. 2 109 252 12 14
[0081] The tables show the 0.2% proof strength R P o,2, the tensile strength Rm, the uniform elongation A g and the elongation at break A are given. It is striking that the strengths of the two alloys are almost identical after casting. However, after heat treatment, a clear difference is evident. While the 0.2% yield strength for the manganese-containing alloy has increased significantly by more than 30%, hardly any increase is observed for the alloy according to the invention; rather, the measured increase is within the tolerance range. Despite the high magnesium content, hardening can be reliably prevented in the described manner, and a naturally hard die-casting alloy can be provided.
Claims
PATENT CLAIMS:
1. A method for producing an aluminum die-casting alloy with a secondary aluminum portion, which in addition to aluminum has silicon, iron, manganese and magnesium as alloying constituents, characterized in that, depending on a magnesium content of the die-casting alloy, a proportion of at least one component of the die-casting alloy is adjusted such that a magnesium-containing primary phase is formed upon cooling of the die-casting alloy.
2. Process according to claim 1, characterized in that the aluminum die-casting alloy for achieving the secondary aluminum content is produced from a starting material containing secondary aluminum which has at least 0.08 wt.% magnesium.
3. Process according to one of the preceding claims, characterized in that the proportion of secondary aluminum in the die-casting alloy is at least 50%.
4. Process according to one of the preceding claims, characterized in that manganese is used as the at least one component.
5. Method according to one of the preceding claims, characterized in that the at least one component is substituted by at least one substitution component, wherein chromium and / or molybdenum is used as the at least one substitution component.
6. Process according to one of the preceding claims, characterized in that a TT-Al-FeMgSi phase is used as the magnesium-containing primary phase.
7. Method according to one of the preceding claims, characterized in that the proportion of chromium and / or molybdenum in the The total amount of the die-casting alloy selected is at least equal to the proportion of manganese in the die-casting alloy.
8. Method according to one of the preceding claims, characterized in that the die-casting alloy is produced with the following composition: - 6.5 to 11.5 wt% silicon, - maximum 0.25 wt% manganese, - 0.06 to 0.6 wt% chromium, - 0.05 to 0.5 wt% magnesium, - 0.05 to 0.4 wt% iron, - optionally 0.001 to 0.3 wt% molybdenum, - optionally 0.004 to 0.2 wt% titanium, - optionally 0.01 to 0.2 wt.% zirconium, - optionally 0.008 to 0.02 wt% strontium, - optionally 0.001 to 0.1 wt% vanadium, - optionally 0.001 to 0.5 wt% copper, - optionally 0.001 to 0.6 wt% zinc, and - Rest aluminum and unavoidable impurities.
9. Aluminium die-casting alloy with secondary aluminium content, in particular produced according to the process according to one or more of the preceding claims, characterized by the following alloying components: - 6.5 to 11.5 wt% silicon, - maximum 0.25 wt% manganese, - 0.06 to 0.6 wt% chromium, - 0.05 to 0.5 wt% magnesium, - 0.05 to 0.4 wt% iron, - optionally 0.001 to 0.3 wt% molybdenum, - optionally 0.004 to 0.2 wt% titanium, - optionally 0.01 to 0.2 wt.% zirconium, - optionally 0.008 to 0.02 wt% strontium, - optionally 0.001 to 0.1 wt% vanadium, - optionally 0.001 to 0.5 wt% copper, - optionally 0.001 to 0.6 wt.% zinc, and - balance aluminum and unavoidable impurities.
10. Structural component for a motor vehicle, made of an aluminum die-cast alloy according to claim 9.