AlSiMgX master alloy and its use in the production of aluminum alloys

Abstract

The present invention relates to an AlSiMgX master alloy that is particularly suitable for increasing the magnesium concentration of an aluminum casting alloy melt. The present invention also relates to a method for increasing the Mg content of an aluminum casting alloy by using an AlSiMgX master alloy in preparing a target aluminum alloy. The AlSiMgX master alloy comprises: 1.3 to 6.5% by weight of Mg, 6.5 to 11.5 wt.% Si, 0-1 wt.% Cu, 0 to 1.0% by weight of Mn, 0.40% by weight or less of Fe, 0.18 wt.% or less of Ti, not more than 0.10% by weight of Sr, The balance is Al and unavoidable impurities. Includes.

Description

[Technical field]

[0001] The present invention relates to a master alloy for increasing the magnesium content of an aluminum alloy melt, in particular an aluminum casting alloy melt. The present invention also relates to a method for preparing a target aluminum alloy by increasing the Mg content of the aluminum casting alloy, and to the use of the master alloy for increasing the Mg content of the aluminum casting alloy. [Background technology]

[0002] Most of the aluminum casting alloys used for shape casting are based on Si and Mg as the main alloying elements. Si gives the alloy good castability and together with Mg allows precipitation hardening. In gravity and low pressure casting, AlSi7Mg type alloys with a Mg range of 0.25-0.45% by weight, e.g. described in European standard EN1706 as EN AC-AlSi7Mg0.3, are the primary casting alloys most used worldwide, although variants with higher Mg contents (up to 0.7% by weight) or some copper additions (up to 1% by weight) are also commonly used. In high pressure die casting of structural parts, AlSiMnMg alloys with Si contents of 7-10% by weight and Mg contents up to 0.6% by weight have become very popular.

[0003] All the aforementioned alloys are usually heat treated to obtain T5, T6 or T7 tempers, where the Mg content plays an important role and allows to adjust the mechanical properties. Figure 1 shows the mechanical properties of AlSi7 alloy in T6 temper as a function of Mg content. Therefore, it is important for casting to adjust the Mg content to a specific level depending on the mechanical property requirements.

[0004] Many foundries routinely increase the Mg content of the melt for one or both of the following reasons: First, some cast products may require a higher strength than can be achieved with commonly purchased alloys. Obtaining this by a specific increase in the Mg content of the alloy eliminates the need for a second alloy. Second, most foundries remelt internal scrap consisting of feeders, gating systems, scrap parts or chips from machining operations. When remelting such scrap, often in the form of small pieces, Mg tends to be consumed to some extent, leading to a decrease in the Mg content in the melt. Therefore, the addition of Mg to the melt is necessary to compensate for the Mg consumption.

[0005] Increasing the Mg content of aluminum alloys is conventionally done by adding pure Mg metal to the melt in a transfer crucible before degassing or directly in the casting furnace. If not submerged by suitable means, pure Mg metal tends to float on the melt surface, which promotes consumption and oxide formation. Measurements have shown that this method very often leads to a significant increase in the oxide content (Mg oxides and mixed AlMg oxides / spinel) in the melt, in addition to low and unpredictable yields due to Mg burn-off.

[0006] Therefore, an improved method for increasing the Mg content of an aluminum melt that provides a solution to the aforementioned problems is desired. Summary of the Invention

[0007] The present invention provides a solution that alleviates at least some or all of the problems associated with conventional methods for increasing the Mg content in aluminum alloys.

[0008] The present invention solves or at least alleviates problems associated with conventional methods for increasing the Mg content in aluminum alloys by providing an AlSiMgX master alloy for use in preparing aluminum-silicon based casting alloys containing Mg.

[0009] The present invention also provides a method for preparing an aluminum target alloy using the above-described AlSiMgX master alloy.

[0010] In this disclosure, the following terms, unless otherwise indicated, shall be construed and understood in accordance with the following definitions.

[0011] The term "base alloy" as used herein means an initial aluminum-based alloy prepared according to common methods in a melting furnace after melting input materials such as ingots, pre-alloyed ingots, master alloys, alloying elements, process scrap, feeders, chips, etc.

[0012] The term "master alloy" as used herein means an aluminum alloy rich in certain alloying elements that are added to a base alloy to achieve / adjust a target aluminum alloy composition. In this disclosure, the AlSiMgX master alloy is rich in Mg with other alloying elements essentially corresponding to the aluminum base alloy and thus the aluminum target alloy.

[0013] The term "target alloy" as used herein means an aluminum alloy achieved after adding alloying elements to a base aluminum alloy, for example by using a master alloy, to achieve a target composition of the aluminum alloy. In this disclosure, the term "target aluminum alloy" should be understood to mean an aluminum base alloy to which an AlSiMgX master alloy has been added, which results in an increased Mg concentration in the target aluminum alloy compared to the aluminum base alloy.

[0014] As used herein, the term "alloying element" means the intentional addition of an element to a base metal (in this disclosure, aluminum) for the purpose of improving the workability of the base metal, or for the purpose of modifying the metallurgical structure of the base metal, thereby modifying its mechanical, corrosion, electrical, or thermal properties. This term does not include unavoidable impurities, unless expressly stated otherwise.

[0015] According to a first aspect, the present invention provides an AlSiMgX master alloy for increasing the Mg content (the term "Mg content" may also be referred to herein as "Mg concentration") in an aluminum base alloy in the preparation of a target aluminum alloy. The aluminum base alloy may be an AlSiMgX master alloy. The aluminum base alloy is preferably an AlSiMg alloy having a composition essentially corresponding to the AlSiMgX master alloy, except for the generally lower Mg concentration in the aluminum base alloy compared to the AlSiMgX master alloy. The target aluminum alloy may be an AlSiMg alloy. The aluminum target alloy is preferably an AlSiMg alloy having a composition essentially corresponding to the AlSiMgX master alloy and the aluminum base alloy, except for the generally lower Mg concentration compared to the AlSiMgX master alloy, but higher compared to the aluminum base alloy.

[0016] The AlSiMgX master alloy according to the first aspect has the following composition: 1.3 to 6.5% by weight of Mg, 6.5 to 11.5 wt.% Si, 0-1.0 wt.% Cu, 0 to 1.0% by weight of Mn, 0.40% by weight or less of Fe, 0.18 wt.% or less of Ti, 0.10% by weight or less of Sr, and The balance is Al and unavoidable impurities. has.

[0017] The concentration of each of the alloying elements selected from the group consisting of Si, Cu, Mn, Fe, Ti and Sr in the AlSiMgX master alloy should correspond to the concentration of the same alloying element in the aluminum base alloy to which the AlSiMgX master alloy is added, but the Mg content in the AlSiMgX master alloy can be significantly higher than in said aluminum base alloy. By making the concentrations of said alloying elements (except Mg) in the AlSiMgX master alloy correspond to the concentrations of said alloying elements in the base alloy, it is possible to adjust the Mg content without changing the overall chemistry of the base alloy / target alloy. This AlSiMgX master alloy gives a predictable yield in the aluminum target alloy prepared with the AlSiMgX master alloy, does not deteriorate the melting properties and does not change the overall chemical composition due to dilution effects. By adding the appropriate amount of AlSiMgX master alloy with the appropriate base composition, any consumption of Mg can be adjusted in a reliable and consistent manner.

[0018] The content of Mg in the AlSiMgX master alloy is 1.3-6.5 wt%. In another embodiment, the content of Mg in the AlSiMgX master alloy may suitably be 1.3-5.5 wt%, such as 1.3-2.5 wt%, 1.5-2.5 wt%, 1.5-2.0 wt%, 2.0-3.0 wt%, 2.5-3.5 wt%, 3.4-4.0 wt%, 4.0-5.5 wt%, 4.5-5.5 wt%, or 4.0-4.6 wt%. Alternative concentration ranges of Mg in the AlSiMgX master alloy allow for the preparation of different AlSiMgX master alloy compositions that can be tailored to the desired increase in Mg content in different target aluminum alloys compared to the base aluminum alloy.

[0019] The Si content in the AlSiMgX master alloy is 6.5 to 11.5 wt %. The content of Si in the AlSiMgX master alloy may be 6.5-7.5 wt% or 9-11.5 wt%. The above Si range is used in many aluminum casting alloys based on Si and Mg as the main alloying elements. Therefore, the AlSiMgX master alloy containing the above Si range is particularly suitable for adjusting the Mg content of such AlSiMg casting alloys. In one example, the content of Si in the AlSiMgX master alloy is 6.5-11.5 wt%, and the content of Mn is 0.4-0.8 wt%. In another example, the content of Si in the AlSiMgX master alloy is 6.5-8.5 wt%, and the content of Mn is 0.4-0.8 wt%. In a further example, the content of Si in the AlSiMgX master alloy is 9.0-11.5 wt%, and the content of Mn is 0.4-0.8 wt%. The AlSiMgX master alloys containing Si and Mn are particularly suitable for adjusting the Mg content of AlSiMnMg casting alloys.

[0020] In one example of an AlSiMgX master alloy, the Si content is 6.5-7.5 wt. % and the Cu content is 0.2-0.7 wt. %. The AlSiMgX master alloy containing Si and Cu is particularly suitable for adjusting the Mg content of AlSiCuMg casting alloys.

[0021] The content of Fe in the AlSiMgX master alloy is up to 0.40 wt%. In alternative embodiments, the amount of Fe in the AlSiMgX master alloy may be up to 0.15 wt%. The content of Ti in the AlSiMgX master alloy is up to 0.18 wt%. In alternative embodiments, the amount of Ti in the AlSiMgX master alloy may be 0.05-0.15 wt%. The content of Sr in the AlSiMgX master alloy is up to 0.10 wt%. In alternative embodiments, the amount of Sr in the AlSiMgX master alloy may be 0.02-0.04 wt%.

[0022] The AlSiMgX master alloys are generally designated as 3xx alloys (according to the Aluminum Association Designation System nomenclature), EN AC-42xxx alloys (AlSi7Mg), EN AC-43500 alloys (AlSi10MnMg), or EN AC-45500 alloys (AlSi7Cu0.5Mg) (European Standards EN1706 and / or EN 1676), where the AlSiMgX master alloy has a higher Mg concentration compared to said standard alloy, the Mg content being 1.3-6.5 wt%, for example 1.3-5.5 wt%, or 1.3-2.5 wt%, or 1.5-2.5 wt%, or 1.5-2.0 wt%, or 2.0-3.0 wt%, or 2.5-3.5 wt%, or 3.4-4.0 wt%, or 4.0-5.5 wt%, or 4.5-5.5 wt%, or 4.0-4.6 wt%. The above standard casting alloys represent typical casting alloys. An AlSiMgX master alloy based on such a standard casting alloy, but with an increased amount of Mg compared to the standard composition, can be adapted to the standard casting alloy and the specific increase in Mg concentration without changing the overall chemistry of the alloy.

[0023] The AlSiMgX master alloy may be in the form of an ingot, rod, wire, pellet, briquet, foil, waffle, button, rod, powder or splatter. Preferably, the AlSiMgX master alloy is in the form of an ingot. The AlSiMgX master alloy ingot may have a weight of 6.5, 7.5 or 9.2 kg, or other standard ingot weights used in the aluminum smelting industry.

[0024] According to a second aspect of the present disclosure, there is provided a method for adjusting the concentration of Mg in an aluminium base alloy in the preparation of an aluminium target alloy, the method comprising: providing an AlSiMgX master alloy according to the present disclosure and the first aspect of the present disclosure; providing an aluminum-based alloy having essentially the same composition as an AlSiMgX master alloy, except that the Mg concentration is lower compared to the Mg concentration of the AlSiMgX master alloy; Increasing the Mg content of an aluminum-based alloy by adding a predetermined amount of an AlSiMgX master alloy to the aluminum-based alloy, while leaving the concentrations of other alloying elements essentially unchanged; Includes.

[0025] By the method of the present invention, the concentrations of other alloying elements selected from the group comprising Si, Cu, Mn, Fe, Ti, Sr in the aluminum target alloy are essentially unchanged compared to the aluminum base alloy after the addition of the AlSiMgX master alloy. The term "essentially" should be understood in this context and in this disclosure to mean that the concentrations of the alloying elements are not changed in an amount that would change the properties of the aluminum target alloy, since the modification of the aluminum target alloy is based on adjusting the Mg concentration.

[0026] The AlSiMgX master alloy may be added to the melting furnace before, during, or after melting of the aluminum base alloy.

[0027] The AlSiMgX master alloy may be added to the transfer crucible before, during, or after it is filled with the molten aluminum base alloy.

[0028] The AlSiMgX master alloy may be added to the holding or casting furnace before, during, or after the aluminum base alloy is poured.

[0029] The AlSiMgX master alloy may be added to a continuous melting furnace and the AlSiMgX master alloy may be fed periodically to the furnace to replace Mg losses.

[0030] The AlSiMgX master alloy may be added in the form of ingots, rods, wires, pellets, briquettes, foils, waffles, buttons, rods, powders or splatters.

[0031] According to a third aspect, the present disclosure provides a method for preparing an AlSiMgX master alloy according to the present disclosure, the method comprising providing an aluminum base alloy in a solid or molten state, optionally measuring the concentration (weight percent) of each alloying element in the aluminum base alloy, estimating and adding an appropriate amount of Mg to the aluminum base alloy to obtain a desired concentration of Mg in the AlSiMgX master alloy, and casting the molten AlSiMgX master alloy. The aluminum base alloy on which the AlSiMgX master alloy is based may be selected from 3xx alloys (according to the Aluminum Association Designation System nomenclature), EN AC-42xxx, EN AC-43500 (AlSi10MnMg) or EN AC-45500 (AlSi7Cu0.5Mg) alloys (according to European Standards EN 1706 and / or EN 1676).

[0032] The method for preparing the AlSiMgX master alloy may include adding appropriate amounts of alloying elements to an aluminum base alloy, adjusting the amount of any other alloying elements selected from the group consisting of Si, Cu, Fe, Mn, Ti and Sr to obtain a desired composition of the AlSiMgX master alloy. Preferably, the method includes casting the AlSiMgX master alloy into an ingot, rod, wire, pellet or briquette. The cast AlSiMgX master alloy may be further processed into foil, waffle, button, rod, wire, powder or splatter form.

[0033] According to a fourth aspect, the present disclosure further provides a use of an AlSiMgX master alloy according to the present disclosure, wherein the AlSiMgX master alloy is added to an aluminum base alloy to increase the Mg content in the aluminum base alloy while leaving essentially the same concentration of other alloying elements in the aluminum base alloy. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 shows the mechanical properties of AlSi7 in the T6 temper as a function of Mg content. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] The present disclosure relates to an AlSiMgX master alloy that is particularly suitable for increasing the Mg content of an aluminum casting alloy melt. The AlSiMgX master alloy according to the present disclosure is therefore particularly suitable for use in a method for preparing a target aluminum alloy. Preferably, the AlSiMgX master alloy contains essentially the same overall alloying elements in the same concentrations as desired in the target aluminum alloy, except for a higher content of Mg.

[0036] The AlSiMgX master alloy according to the present disclosure has 1.3 to 6.5% by weight of Mg, 6.5 to 11.5 wt.% Si, 0-1.0 wt.% Cu, 0 to 1.0% by weight of Mn, 0.40% by weight or less of Fe, 0.18 wt.% or less of Ti, Contains 0.10% by weight or less of Sr, the balance being Al and unavoidable impurities.

[0037] The AlSiMgX master alloy is used in a method for preparing a target aluminum alloy by adding an appropriate amount of the AlSiMgX master alloy to an aluminum base alloy.

[0038] The composition of any particular AlSiMgX master alloy according to the present disclosure depends on the composition of the desired target aluminum alloy, which also corresponds to the composition of the base aluminum alloy. The AlSiMgX master alloy shall have essentially the same concentrations of alloying elements (selected from the group consisting of Si, Cu, Fe, Mn, Ti and Sr) as the target alloy, except for the concentration of Mg. By "essentially the same concentrations" it is meant that the concentrations of said alloying elements (except Mg) in the AlSiMgX master alloy correspond to the target aluminum alloy, so that the concentrations of said alloying elements in the target aluminum alloy after adding the AlSiMgX master alloy to the base aluminum alloy generally have corresponding concentrations, except for the concentration of Mg, which is increased in the target aluminum alloy compared to the base alloy. For a given aluminum base alloy, the AlSiMgX master alloy of the present invention can be prepared. It is understood that the weight percent concentration of each alloying element in the base alloy can be determined by methods commonly known in the art.

[0039] The AlSiMgX master alloy may be used in a method of preparing a target aluminum alloy by adding the AlSiMgX master alloy to an aluminum base alloy. The preferred aluminum base alloy may be selected from the 3xx series designated by the Aluminum Association, or may be selected from other European or domestic casting alloys. The aluminum base alloy may be an EN AC-42xxx, EN AC-43500 (AlSi10MnMg) or EN AC-45500 (AlSi7Cu0.5Mg) alloy according to European standards EN1706 and / or EN1676. The base alloy to which the AlSiMgX master alloy is added is subjected to measurement of the alloying elements and their concentrations in the AlSiMgX master alloy.

[0040] The Mg concentration in the AlSiMgX master alloy is 1.3-6.5 wt%. For some applications, the Mg concentration in the AlSiMgX master alloy may be in the range of 1.3-5.5 wt%, or 1.3-4.5 wt%, or 1.3-2.5 wt%, or 1.5-2.5 wt%, or 1.5-2.0 wt%, or 2.0-3.0 wt%, or 2.5-3.5 wt%, or 3.4-4.0 wt%, or 4.0-5.5 wt%, or 4.5-5.5 wt%, or 4.0-4.6 wt%. The concentration of Mg in the AlSiMgX master alloy generally depends on the desired increase in Mg in the target aluminum alloy compared to the base aluminum alloy.

[0041] The Si concentration in the AlSiMgX master alloy is 6.5-11.5 wt%. In some examples, the Si concentration in the AlSiMgX master alloy may be in the range of 6.5-7.5 wt%. Some gravity and low pressure aluminum casting alloys are of the AlSi7Mg type, and therefore an AlSiMgX master alloy having 6.5-7.5 wt% Si is particularly suitable for such AlSi7Mg type alloys. In another example, the Si concentration in the AlSiMgX master alloy may be in the range of 9-11.5 wt%, which is particularly suitable for addition to AlSi10Mg type alloys. AlSiMgX master alloys containing 6.5-11.5 wt% Si, for example 6.5-8.5 wt% Si or 9.0-11.5 wt% Si, together with 0.4-0.8 wt% Mn, are particularly suitable for addition to AlSiMnMg type alloys such as AlSi7MnMg and AlSi10MnMg type alloys, and AlSiMgX master alloys containing 6.5-7.5 wt% Si and 0.2-0.7 wt% Cu are particularly suitable for addition to AlSi7MgCu0.5 type alloys.

[0042] The Fe concentration in the AlSiMgX master alloy should be 0.40 wt.% or less, such as 0.15 wt.% or less.

[0043] The Ti concentration in the AlSiMgX master alloy should be 0.18 wt % or less, for example, 0.05 to 0.15 wt %.

[0044] The Sr concentration in the AlSiMgX master alloy should be 0.10 wt % or less, for example, 0.02 to 0.04 wt %.

[0045] It is understood that the composition of the AlSiMgX master alloy may be varied within the generally defined composition according to the appended claims by combining the illustrated ranges of the alloying elements.

[0046] The AlSiMgX master alloy of the present disclosure is prepared according to the generally known methods of producing casting alloys. Commercially available pure aluminum, scrap aluminum alloys with recycled aluminum metal, or combinations thereof, as well as the alloying elements of the respective base alloys, can be used as starting materials. The AlSiMgX master alloy is preferably based on 3xx series alloys (according to the Aluminum Association Designation System nomenclature), EN AC-42xxx, EN AC-43500 (AlSi10MnMg) or EN AC-45500 (AlSi7Cu0.5Mg) alloys (according to European Standards EN1706 and / or EN 1676), with an increased Mg concentration compared to said standard base alloys. A sufficient amount of magnesium is used to provide the calculated final concentration of magnesium in the AlSiMgX master alloy. After the final element is added, it is desirable to adjust the temperature immediately to provide fluidity for casting and, depending on the stirring characteristics of the furnace, to provide a product with consistent chemistry from the beginning to the end of the fill when cast to eliminate concerns about segregation.

[0047] The cast AlSiMgX master alloy may be further processed or the final step in its preparation may be modified to produce any desired form of AlSiMgX master alloy. Such forms include foil, waffle, ingot, button, rod, wire, pellet, powder, briquette, and splatter. However, for many applications, the preferred form of AlSiMgX master alloy is an ingot. The ingot can be of the corresponding shape and / or size of the ingot used for the base alloy ingot. Another preferred form of AlSiMgX master alloy is a continuous cast (directly cooled) ingot, where the developing Mg-containing phase is small in size and well distributed due to the high solidification rate. The AlSiMgX master alloy ingot with its small in size and well distributed Mg-containing phase promotes rapid dissolution of the master alloy when added to a molten aluminum base alloy.

[0048] The AlSiMgX master alloy according to the present invention is used in the preparation of the final target aluminum alloy. The AlSiMgX master alloy may be added to the melting furnace (before, during, or after melting), to the melt in a transfer crucible, or to the melt in a holding or casting furnace. For example, in the case of a single furnace melting system where the cast alloy is cast from the melting furnace, the base aluminum alloy is often prepared by using pre-alloyed cast aluminum alloy ingots. Alternatively, the base aluminum alloy may be prepared using commercially pure aluminum, scrap aluminum alloys with recycled aluminum metal, or a combination thereof, as well as the required alloying elements. Sufficient material is added until the base charge is achieved, excluding the amount of AlSiMgX master alloy that may be added later. The temperature is raised to above the melting point, typically 700-800°C. The appropriate amount of AlSiMgX master alloy material may then be added to achieve the desired final chemistry of the target alloy. Advantageously, the surface of the molten aluminum base alloy is skimmed to remove oxides before the addition of the AlSiMgX master alloy.

[0049] Alternatively, depending on the expected nominal Mg content calculated based on the composition of the input material (base aluminum alloy), an appropriate amount of AlSiMgX master alloy can be added to the input material before melting in order to directly achieve the desired Mg content after complete melting of the input material and the AlSiMgX master alloy material.

[0050] In another example, the AlSiMgX master alloy according to the present disclosure can be added to a continuous melting furnace, such as a shaft furnace or a chip melting furnace, where the expected standard Mg losses due to consumption during melting are usually very well known. Depending on the melting capacity per hour and the necessary compensation of Mg losses or the desired increase in Mg content, the AlSiMgX master alloy ingots can be fed to the melt, for example, at regular periods.

[0051] In a further example, the AlSiMgX master alloy according to the present disclosure can be added to the base aluminum alloy as it is poured in a holding or casting furnace. This provides a stirring action and minimizes the time and temperature for making the alloying addition, thereby minimizing oxidation of some of the alloying elements, particularly Mg. The alternative of adding the AlSiMgX master alloy to a filled holding furnace requires adequate stirring.

[0052] In yet another alternative, the AlSiMgX master alloy according to the present disclosure can be added outside of the melting furnace, for example in a transfer crucible, so that the base alloy melt composition in the melting furnace is not affected. Preferably, the addition of the AlSiMgX master alloy is made before the empty transfer crucible is filled, or to the melt in the transfer crucible before the final rotor degassing process. Again, this provides a stirring action and minimizes the time and temperature to make the alloy addition, thereby minimizing oxidation of some of the alloying elements.

[0053] In a preferred embodiment of the present invention, the AlSiMgX master alloy is in the form of an ingot having a size and Mg concentration that results in a stepwise and / or constant increase in Mg concentration when one or more AlSiMgX master alloy ingots are added to a quantity of base aluminum alloy. The AlSiMgX master alloy ingot may have a weight of 6.5 kg, 7.5 kg or 9.2 kg, the size corresponding to a commonly used base aluminum ingot. The addition of one AlSiMgX master alloy ingot to a quantity of base aluminum alloy may increase the Mg concentration in the target aluminum alloy by, for example, 0.1 wt.% (percentage points). Table 1 shows examples of sizes and Mg ranges of AlSiMgX master alloy ingots that result in a constant Mg increase (wt.%) in the target aluminum alloy by adding one ingot to 1000 kg of base alloy. The use of such a "standardized" AlSiMgX master alloy ingot system facilitates and simplifies the production of the target aluminum alloy. It should be noted that Table 1 shows only exemplary alloys for a better understanding of the present invention, and therefore the examples shown in Table 1 should not be construed as limiting the present invention, since there are a variety of possible master alloy compositions within the scope defined in the appended claims.

[0054] [Table 1]

[0055] The following examples illustrate the uses and advantages of the AlSiMgX master alloys according to the present disclosure. The illustrated examples should not be construed as limiting the invention.

[0056] A first illustrative example concerns a 3xx base alloy nominally containing 7 wt% Si, 0.12 wt% Fe, 0.12 wt% Ti, 0.02 wt% Sr, and 0.28 wt% Mg, balance Al. In order to meet the required strength requirements, the Mg concentration shall be increased to 0.29 wt%. By adding 6.5 kg of an AlSiMgX master alloy ingot with the same nominal composition as the base alloy but with 1.9 wt% Mg to 1000 kg of the above mentioned base alloy melt, the Mg content of the melt is nominally increased by 0.01 wt%, i.e. the final Mg content is 0.29 wt%. Similarly, the addition of two ingots nominally increases the Mg content by 0.02 wt%. It must be taken into account that the calculated nominal loss of melting temperature is about 7.5 degrees per ingot added to 1000 kg of melt. The time for melting and complete dissolution of the AlSiMgX master alloy ingot can be expected to be within 2-3 minutes. Pouring or stirring (e.g., by rotor degassing) the liquid base alloy onto the master alloy ingot further reduces the melting and dissolution time.

[0057] A second illustrative example concerns a 3xx base alloy nominally comprising 7 wt% Si, 0.12 wt% Fe, 0.12 wt% Ti, 0.02 wt% Sr and 0.28 wt% Mg, balance Al. To meet the required strength requirements, the Mg concentration shall be increased to 0.32 wt%. By adding two 6.5 kg AlSiMgX master alloy ingots with the same composition as the base alloy but with 3.8 wt% Mg to 1000 kg of said base alloy melt, the Mg content of the melt is nominally increased by 0.04 wt%, i.e. to a final value of 0.32 wt%.

[0058] The AlSiMgX master alloy of the present invention offers several advantages over conventional methods of adding Mg to aluminum alloys. The AlSiMgX master alloy provides an enriched amount of Mg in the proper proportions required to produce a specific target alloy, thereby allowing the desired composition to be reached with only one master alloy addition. Due to the finely distributed Mg phase, the AlSiMgX master alloy provides a high melting rate, thereby reducing furnace cycle time or process time. The AlSiMgX master alloy reduces losses caused by, for example, consumption, and further reduces melt processing time, both for faster melting and easier handling, compared to conventional methods. The AlSiMgX master alloy also offers more consistent chemical control in certain cases, for more reliable yields, compared to the addition of pure Mg or binary AlMg alloys. These advantages increase the efficiency of shape casting foundries and reduce production costs.

[0059] The following examples relate to AlSiMgX master alloys according to the present disclosure.

[0060] <Example 1> 233.1 kg of AlSi7Mg alloy was prepared in an electric resistance furnace. The temperature of the melt was 740°C. The composition of the alloy was analyzed by optical emission spectroscopy (OES) and the results are shown in Table 2. The Mg concentration was 0.309 wt%.

[0061] The AlSiMgX master alloy according to the invention was added to the melt in an amount of 233.1 kg. The composition of the AlSiMgX master alloy is shown in Table 2. The Mg concentration of the master alloy was 1.37 wt.%. An amount of master alloy (5.009 kg) was added to the melt, corresponding to a theoretical increase in Mg concentration of 0.0223 wt.%. After melting of the master alloy, the Mg concentration increased by 0.0249 wt.% with an estimated yield of 111.5%. A person skilled in the art would conclude that the deviation from 100% yield is due to uncertainties in the chemical analysis (OES).

[0062] [Table 2]

[0063] <Example 2> 1.585 kg of AlSi7Mg alloy was melted in an electric resistance furnace. The temperature of the melt was 720°C. The composition of the alloy analyzed by OES is given in Table 3. The Mg concentration was 0.3043 wt%. An AlSiMgX master alloy according to the invention was added to the melt of 1.585 kg. The composition of the master alloy is given in Table 3. The Mg concentration of the master alloy was 1.37 wt%. An amount of master alloy (0.1592 kg) corresponding to a theoretical increase in Mg concentration of 0.0973 wt% was added to the melt. After melting of the master alloy, the Mg concentration increased by 0.0957 wt% with an estimated yield of 98.4%. Again, the deviation from 100% yield can be explained by the uncertainty of the OES analysis.

[0064] [Table 3]

[0065] <Example 3> For the wheel casting, 891 kg of AlSi7Mg melt from the melting furnace was filled into a transfer crucible. The weight of the melt was measured by weighing the crucible before and after filling. The composition of the alloy analyzed by optical emission spectroscopy (OES) is given in Table 4. The Mg concentration was 0.3021%. An AlSiMgX master alloy according to the invention was added to the 981 kg melt. The composition of the AlSiMgX master alloy is given in Table 4. The Mg concentration of the master alloy was 1.37% by weight. Before the 4 min degassing treatment, one master alloy ingot (9.2 kg) was added to the melt, which corresponds to a theoretical increase in Mg concentration of 0.011% by weight. In an OES sample taken immediately after the treatment, the Mg concentration was 0.3142% by weight, i.e. an increase of 0.0121% by weight, with an estimated yield of 111%. One skilled in the art would conclude that the deviation from 100% yield is due to uncertainties in the chemical analysis (OES).

[0066] [Table 4]

[0067] The three examples show that the composition of the target alloy has essentially the same composition of alloying elements as the base alloy, except for the amount of Mg, which is increased to a desired concentration.

[0068] Specific details described in the context of various exemplary embodiments are not intended to be construed as limiting. The disclosed embodiments and alternatives of the invention can be readily combined without departing from the scope defined in the appended claims.

Claims

1. 1. An AlSiMgX master alloy for increasing the Mg content in an aluminum-based alloy in the preparation of a target aluminum alloy, the AlSiMgX master alloy comprising: 1.3 to 6.5 wt.% Mg, 6.5 to 11.5 wt.% Si, 0 to 1.0 wt. % Cu, 0 to 1.0 wt. % Mn, 0.40% by weight or less of Fe, 0.18 wt.% or less of Ti, 0.10% by weight or less of Sr, and The balance is Al and unavoidable impurities. The AlSiMgX master alloy.

2. 2. The AlSiMgX master alloy according to claim 1, wherein the Si content is 6.5 to 7.5 wt % or 9.0 to 11.5 wt %.

3. 2. The AlSiMgX master alloy according to claim 1, wherein the Si content is 6.5 to 11.5 wt % and the Mn content is 0.4 to 0.8 wt %.

4. 4. The AlSiMgX master alloy according to claim 3, wherein the Si content is 6.5 to 8.5 wt % or 9.0 to 11.5 wt %, and the Mn content is 0.4 to 0.8 wt %.

5. 2. The AlSiMgX master alloy according to claim 1, wherein the Si content is 6.5 to 7.5 wt % and the Cu content is 0.2 to 0.7 wt %.

6. The AlSiMgX master alloy according to any one of claims 1 to 5, wherein the Sr content is 0.02 to 0.04 wt%.

7. The AlSiMgX master alloy according to any one of claims 1 to 6, wherein the Fe content is 0.15 wt% or less.

8. The AlSiMgX master alloy according to any one of claims 1 to 7, wherein the Ti content is 0.05 to 0.15 wt%.

9. The AlSiMgX master alloy according to any one of claims 1 to 8, wherein the Mg content is 1.3 to 5.5 weight%, 1.3 to 2.5 weight%, 1.5 to 2.5 weight%, 1.5 to 2.0 weight%, 2.0 to 3.0 weight%, 2.5 to 3.5 weight%, 3.4 to 4.0 weight%, 4.0 to 5.5 weight%, 4.5 to 5.5 weight%, or 4.0 to 4.6 weight%.

10. 10. An AlSiMgX master alloy according to any one of the preceding claims, wherein the master alloy is based on 3xx alloys (according to the Aluminium Association Designation System), EN AC-42xxx, EN AC-43500 (AlSi10MnMg) or EN AC-45500 (AlSi7Cu0.5Mg) alloys (according to European Standards EN 1706 and / or EN 1676) and has an increased Mg concentration compared to the standard alloys.

11. The AlSiMgX master alloy of any one of claims 1 to 10, wherein the AlSiMgX master alloy is in the form of an ingot, rod, wire, pellet or briquette, foil, waffle, button, rod, powder, or splatter.

12. 12. The AlSiMgX master alloy of claim 11, wherein the AlSiMgX master alloy is in the form of an ingot.

13. 1. A method for increasing the content of Mg in an aluminum-based alloy in the preparation of a target aluminum alloy, the method comprising: Providing an AlSiMgX master alloy according to any one of claims 1 to 12, providing an aluminum-based alloy having essentially the same composition as the AlSiMgX master alloy, except that the Mg concentration is lower compared to the Mg concentration of the AlSiMgX master alloy; - increasing the Mg content of the aluminum base alloy by adding a predetermined amount of the AlSiMgX master alloy to the aluminum base alloy, while leaving the concentrations of other alloying elements essentially unchanged; A method comprising:

14. 14. The method of claim 13, comprising adding the AlSiMgX master alloy to a melting furnace before, during, or after melting of the aluminum base alloy.

15. 14. The method of claim 13, comprising adding the AlSiMgX master alloy to a transfer crucible before, during, or after it is filled with a molten aluminum base alloy.

16. 14. The method of claim 13, comprising adding the AlSiMgX master alloy to a holding or casting furnace before, during, or after the aluminum base alloy is poured.

17. 14. The method of claim 13, comprising adding the AlSiMgX master alloy to a continuous melting furnace, periodically feeding the AlSiMgX master alloy to the furnace to replace Mg losses.

18. The method of any one of claims 13 to 17, wherein the AlSiMgX master alloy is added in the form of an ingot, rod, wire, pellet or briquette, foil, waffle, button, rod, powder, or splatter.

19. A method for preparing an AlSiMgX master alloy according to any one of claims 1 to 12, said method comprising: Providing an aluminium-based alloy in a solid or molten state; Optionally, measuring the concentration (weight percent) of each alloying element in the aluminum base alloy; - adding an appropriate amount of Mg to an aluminum based alloy to obtain the desired concentration of Mg in said AlSiMgX master alloy; - Adjusting the temperature, if necessary, to provide fluidity for casting; and - casting the AlSiMgX master alloy; A method comprising:

20. 20. The method according to claim 19, wherein the aluminium based alloy is selected from 3xx series alloys (according to the Aluminium Association Designation System nomenclature), EN AC-42xxx alloys, EN AC-43500 alloys (AlSi10MnMg) or EN AC-45500 alloys (AlSi7Cu0.5Mg) (according to European Standards EN 1706 and / or EN 1676).

21. 21. The method of any one of claims 19 to 20, further comprising adjusting the amount of any other alloying elements selected from the group consisting of Si, Cu, Fe, Mn, Ti and Sr by adding appropriate amounts of alloying elements to the aluminum base alloy to obtain a desired composition of the AlSiMgX master alloy.

22. 22. The method of any one of claims 19 to 21, wherein the casting step comprises casting the AlSiMgX master alloy into an ingot, rod, wire, pellet, or briquette.

23. Use of the AlSiMgX master alloy according to any one of claims 1 to 12, wherein a predetermined amount of said AlSiMgX master alloy is added to an aluminum base alloy to increase the Mg content, while the concentrations of other alloying elements in the aluminum base alloy are essentially unchanged.

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