DE102015007929A1 - Cast aluminum alloy, method of manufacturing an aluminum cast alloy component and using an aluminum casting alloy - Google Patents

Abstract

Cast aluminum alloy, consisting of - at least 4 wt .-% to at most 7 wt .-% silicon, - at least 0.5 wt .-% to at most 1.5 wt .-% manganese, - at least 0.03 wt. % to at most 0.3% by weight of zirconium, - other elements: each less than 0.3% by weight and in total not more than 1.2% by weight, - balance aluminum.

Description

The invention relates to an aluminum casting alloy, a method for producing a component from an aluminum casting alloy and a use of an aluminum casting alloy.

From the international patent application with the publication number WO 03/006698 A1 is known a component made of an aluminum alloy, in which as an additional manufacturing step after casting nor a heat treatment, in particular a T5 heat treatment, to obtain the desired properties is necessary. Due to the addition of magnesium, the properties of the cast state change after long-term exposure to temperatures of 120 ° C.

From the European patent application EP 1 612 286 A2 is known an aluminum die casting alloy, which in the cast state not required for crash components ductility in the form of a bending angle VDA 238-100 of more than 45 °.

From the German patent application DE 10 2008 055 928 A1 For example, an aluminum casting alloy is known which requires a solution annealing step of 490 ° C to 540 ° C to exploit its strength potential through the formation of chromium aluminides.

US 2006/0115375 A1 discloses an aluminum casting alloy which has zirconium, the advantage of zirconium addition in this alloy being obtained only in the case of a T6 heat treatment, without any advantages in the cast state.

The invention has for its object to provide an aluminum casting alloy, a method for producing a component from such an aluminum casting alloy and a use of such an aluminum casting alloy, said disadvantages do not occur.

The object is achieved by providing the subject matters of the independent claims. Advantageous embodiments will become apparent from the dependent claims and the description.

• – mindestens 4 Gew.-% bis höchstens 7 Gew.-% Silizium,
• – mindestens 0,5 Gew.-% bis höchstens 1,5 Gew.-% Mangan,
• – mindestens 0,03 Gew.-% bis höchstens 0,3 Gew.-% Zirkonium,
• – sonstige Elemente: jedes für sich genommen weniger als 0,3 Gew.-% und in Summe höchstens 1,2 Gew.-%,
• – Rest Aluminium.

The object is achieved in particular by providing an aluminum casting alloy, which consists of:

• At least 4% by weight to at most 7% by weight of silicon,
• At least 0.5% by weight to at most 1.5% by weight of manganese,
• At least 0.03% by weight to at most 0.3% by weight of zirconium,
• - other elements: each taken by itself less than 0.3% by weight and in total not more than 1.2% by weight,
• - Rest aluminum.

By lowering the silicon concentration to at least 4 wt .-% to at most 7 wt .-%, the proportion of brittle aluminum-silicon eutectic can be reduced. As a result, in particular a fracture constriction and also the bending angle increase as a measure of the ductility of the alloy. The associated decrease in strength is advantageously compensated by the addition of manganese and zirconium in the specified amounts. This makes it possible in particular to obtain a 0.2% proof stress of more than 80 MPa, in particular of more than 100 MPa. The addition of manganese and especially the addition of zirconium leads to solid solution hardening, which raises the yield strength in the cast state to the desired level. The aluminum casting alloy proposed here has its advantageous mechanical properties completely without heat treatment. Instead, such can be completely eliminated. As a result, in the production of a component from the aluminum casting alloy, a component distortion occurring during heat treatment is avoided, and the subsequent straightening process for the component can be dispensed with. This reduces the process times and lowers the investment and component costs. In addition, the alloy is easily punch-riveted and corrosion-resistant in the cast state. In addition, energy consumption and carbon dioxide emissions decrease, which ultimately improves the carbon footprint of the entire vehicle during production when using the aluminum casting alloy in the automotive industry.

The manganese addition also increases at high cooling rates in thin-walled die casting, the 0.2% proof strength by solid solution strengthening of the aluminum dendrites. An indicator of this is the Martens hardness of the alloy, which is measured by nanoindenter in the aluminum dendrites. This effect is particularly pronounced by the addition of even small amounts of zirconium. In addition, zirconium addition increases strength while maintaining the bend angle as a measure of ductility.

An advantageous development of the invention provides that the aluminum casting alloy has silicon with a proportion of at least 4 wt .-% to at most 5 wt .-%. In this area, the already mentioned advantages are realized in a special way.

A development of the invention provides that the aluminum casting alloy has manganese with a proportion of at least 0.81 wt .-% to at most 1.5 wt .-%. In this area, the already mentioned advantages are realized to a special extent.

A development of the invention provides that the aluminum casting alloy has zirconium in a proportion of at least 0.03 wt .-% to at most 0.49 wt .-%. In this area, the already mentioned advantages are realized in a special way.

A development of the invention provides that the other elements in the aluminum casting alloy in total with at most 1.1 wt .-%, preferably at most 1.08 wt .-%, are provided.

Other elements may be, for example, lead, nickel, zinc, or other, especially unavoidable, impurities.

A development of the invention provides that the aluminum casting alloy has at least 0.05 wt .-% to at most 0.3 wt .-% titanium. In particular, a titanium addition, especially in combination with the above-described addition of manganese and zirconium, tends to balance the decrease in strength associated with the lowered silicon content, and to achieve a 0.2% proof stress, especially greater than 100 MPa.

A development of the invention provides that the aluminum casting alloy has titanium with a proportion of at least 0.1 wt .-% to at most 0.3 wt .-%.

A development of the invention provides that the aluminum casting alloy has titanium with a proportion of at least 0.15 wt .-% to at most 0.3 wt .-%. In the areas mentioned here, the advantages already described are realized in a special way.

A development of the invention provides that the aluminum casting alloy has at least 50 ppm to at most 300 ppm - based on the weight - strontium. Here, a strontium addition is used in particular for permanent finishing.

A development of the invention provides that the aluminum casting alloy has at most 0.2 wt .-% iron. Alternatively or additionally, the aluminum casting alloy comprises at most 0.1% by weight of magnesium, preferably at most 0.08% by weight of magnesium. Alternatively or additionally, the aluminum casting alloy preferably has at most 0.1% by weight of copper. Alternatively or additionally, the aluminum casting alloy has at most 0.1% by weight of zinc. In particular, the limitation of the curing elements magnesium, copper and zinc which are typical in other alloys, in any case less than 0.1% by weight, has the effect that the aluminum casting alloy proposed here does not exhibit any ductility-reducing curing effects, in particular up to a temperature of 230 ° C. This ensures stability of the mechanical properties even under long-term temperature stress. Furthermore, the aluminum casting alloy is ideal for punch riveting and has the additional limitation of zinc, copper and iron increased corrosion resistance.

A development of the invention provides that the aluminum casting alloy at least 0.01 wt .-% to at most 0.15 wt .-% molybdenum, preferably at least 0.05 wt .-% to at most 0.09 wt .-% molybdenum , having. By adding molybdenum, the elongation can be further improved without sacrificing the other mechanical properties.

Alternatively or additionally, the aluminum casting alloy preferably has at least 0.05 wt% to at most 0.15 wt% chromium. As a result, the morphology of the Fe / Mn-containing intermetallic phases can be positively influenced by the formation of Al15 (Fe, Mn, Cr) 3Si2 phases.

A development of the invention provides that the aluminum casting alloy has a 0.2% proof strength of greater than 80 MPa, preferably greater than 90 MPa, preferably greater than 100 MPa. Alternatively or additionally, the aluminum casting alloy preferably has a tensile strength R _m of greater than 180 MPa. Alternatively or additionally, the aluminum casting alloy preferably has an elongation at break A5 greater than 8%, preferably greater than 10%. Alternatively or additionally, the aluminum casting alloy preferably follows a bending angle VDA 238-100 in accordance with the current version of the date of the present application determining date of greater than 40 °, preferably greater than 45 °. The cast aluminum alloy preferably has at least one of the mechanical properties mentioned here, particularly preferably all the mechanical properties mentioned here in the cast state without heat treatment. Thus, an aluminum casting alloy with excellent mechanical properties in the cast state without additional heat treatment can be displayed.

A development of the invention provides that a manganese concentration of the aluminum casting alloy is matched to a silicon and / or an iron concentration such that the strength of the aluminum casting alloy is increased. In particular, the manganese concentration is preferably matched to the iron and silicon content of the melt in the production of the aluminum casting alloy. Alternatively or additionally, the manganese concentration is preferably matched to a silicon and / or an iron concentration such that the aluminum casting alloy forms fine-block, finely divided Al15 (Fe, Mn) 3Si2 phases, which increase the strength.

• – mindestens 4 Gew.-% bis höchstens 7 Gew.-% Silizium,
• – mindestens 0,5 Gew.-% bis höchstens 1,5 Gew.-% Mangan,
• – mindestens 0,15 Gew.-% bis höchstens 0,3 Gew.-% Titan,
• – mindestens 0,03 Gew.-% bis höchstens 0,3 Gew.-% Zirkonium,
• – mindestens 50 ppm bis höchstens 300 ppm – in Gewichtsanteilen – Strontium,
• – höchstens 0,2 Gew.-% Eisen,
• – höchstens 0,08 Gew.-% Magnesium,
• – höchstens 0,1 Gew.-% Kupfer,
• – höchstens 0,1 Gew.-% Zink,
• – optional mindestens 0,01 Gew.-% bis höchstens 0,15 Gew.-% Molybdän, und/oder
• – optional mindestens 0,05 Gew.-% bis höchstens 0,15 Gew.-% Chrom,
• – Rest Aluminium und unvermeidbare Verunreinigungen.

A further development of the invention provides that an aluminum casting alloy is created n becomes, which consists of:

• At least 4% by weight to at most 7% by weight of silicon,
• At least 0.5% by weight to at most 1.5% by weight of manganese,
• At least 0.15% by weight to at most 0.3% by weight of titanium,
• At least 0.03% by weight to at most 0.3% by weight of zirconium,
• At least 50 ppm to at most 300 ppm by weight - strontium,
• Not more than 0.2% by weight of iron,
• At most 0.08% by weight of magnesium,
• At most 0.1% by weight of copper,
• At most 0.1% by weight of zinc,
• Optionally at least 0.01% by weight to at most 0.15% by weight of molybdenum, and / or
• Optionally at least 0.05% by weight to at most 0.15% by weight of chromium,
• - Remaining aluminum and unavoidable impurities.

Unavoidable impurities preferably occur at most in a proportion of 0.1% by weight.

In the aluminum casting alloy specifically proposed here, the advantages already mentioned above are realized in a special way.

The object is also achieved by providing a method for producing a component, wherein the component is produced from an aluminum casting alloy according to one of the embodiments described above, wherein the following steps are used in the context of the method: The aluminum casting alloy is made at least one master alloy and / or chemical elements, in particular pure chemical elements, melted, and the aluminum casting alloy is poured at a temperature of at least 700 ° C to at most 750 ° C in a mold. By using the aluminum casting alloy according to the invention, a heat treatment necessary for previously established alloys is completely eliminated, and the component produced in this way can, after the finishing, ideally be further processed and installed without further straightening effort.

Preferably, the casting of the cast aluminum alloy is carried out in a tempered and / or forced or vacuum-vented mold, more preferably in a tempered and / or forced or vacuum-vented permanent mold. The tempering of the mold, in particular the forced or vacuum-vented permanent mold, has the advantage that the aluminum casting alloy is cooled in a targeted and controlled manner by the temperature control and thus the service life of the casting tool is increased by cooling it. Incidentally, if the casting temperature is too low, there is a risk of insufficient mold filling and cold runs.

A development of the invention provides that the cast aluminum alloy is cast in the die-casting or in a low-pressure casting process.

A development of the invention provides that the thus cast component is cooled after removal from the mold to air and / or water. This realizes in a special way the advantages of the aluminum casting alloy.

A development of the invention provides that in the context of the method a safety-relevant, in particular crash-relevant, preferably thin-walled component, in particular for a motor vehicle, is produced. The aluminum casting alloy proposed here and the production method proposed here are particularly suitable for the production of crash-relevant, thin-walled components for use in motor vehicle construction.

A development of the invention provides that is dispensed with a heat treatment. The component is produced without heat treatment from the cast aluminum alloy in the cast state. Eliminating heat treatment reduces process times and lowers capital and component costs. At the same time, energy consumption and carbon dioxide emissions are reduced, which in particular improves the carbon dioxide balance of an entire vehicle during its production.

Finally, the object is also achieved by providing use of an aluminum casting alloy according to one of the previously described exemplary embodiments for producing a component in motor vehicle construction. As part of the use, the advantages that have already been explained in connection with the aluminum casting alloy and the production process are realized. The aluminum casting alloy is particularly preferably used for producing a safety component, in particular a crash-relevant, thin-walled component in motor vehicle construction.

The description of the aluminum casting alloy as well as the manufacturing process and the use are to be understood as complementary to each other. Features that have been explained explicitly or implicitly in connection with the manufacturing process and / or use are preferably features of a preferred embodiment of the aluminum casting alloy. Process or use steps that have been explicitly or implicitly described in the context of the aluminum casting alloy are preferably individually or in combination with each other Steps A preferred embodiment of the manufacturing process or use. These are characterized in particular by at least one step, which is due to at least one feature of an inventive or preferred embodiment of the aluminum casting alloy. The cast aluminum alloy is characterized in particular by at least one feature which is due to at least one step of an inventive or preferred embodiment of the manufacturing method and / or the use.

The invention will be explained in more detail below with reference to the drawing. Showing:

1 a schematic representation of the change of a phase proportion of Al-Si eutectic by changing the silicon concentration;

2 a schematic, diagrammatic representation of the dependence of the yield strength and the bending angle of the phase fraction of the Al-Si eutectic, and

3 an influence of manganese and zirconium on the Martens hardness of the aluminum mixed crystal.

1 shows a schematic representation of the change in the phase content of Al-Si eutectic (dark) by changing the silicon concentration. It shows 1a ) an aluminum-silicon alloy with 4 wt .-% silicon and 23% eutectic. 1b ) shows an aluminum-silicon alloy with 6 wt .-% silicon and 38% eutectic, and 1c ) shows an aluminum-silicon alloy with 8 wt .-% silicon and 55% eutectic. Based on 1 It can be seen that by lowering the silicon concentration to less than 7% by weight, the proportion of the as-cast aluminum-silicon eutectic is lowered.

2 shows a schematic, diagrammatic representation of the dependence of 0.2% proof stress R _p0.2 and the bending angle α of the phase _{portion of} the aluminum-silicon eutectic. In this case, the phase fraction P of aluminum-silicon eutectic in percent is given as the x-coordinate, while on the y-axis, on the one hand, the 0.2% yield strength R _p0.2 and, on the other hand, the bending angle α - in particular according to VDA 238-100 in the version valid at the time of the present application - is applied. A first curve K1 represents the 0.2% proof stress R _p0.2 , with a second curve K2 representing the bending angle α. The measuring points are here in turn assigned to aluminum-silicon alloys with 4 wt .-% silicon (Si4), 6 wt .-% silicon (Si6) and 8 wt .-% silicon (Si8). It can be seen that as the silicon concentration decreases, the bending angle as a measure of ductility increases, while the 0.2% proof stress decreases.

The strength decrease associated with the lowered silicon content is compensated according to the invention in the aluminum-silicon alloy by addition of manganese and zirconium and preferably of titanium. As a result, in particular a 0.2% proof stress greater than 100 MPa can be achieved.

3 shows a schematic, diagrammatic representation of the influence of manganese and zirconium on the Martens hardness of the aluminum mixed crystal. Here, the Marten hardness of the aluminum mixed crystal is measured here with nanoindenter and serves as a measure of the solid solution hardening by adding these elements. It shows 3a ) Marten hardness HM in MPa plotted against the manganese concentration in wt .-%, wherein 3b ) shows the effect of adding zirconium, in particular the effect of adding 0.1% by weight of zirconium. In this case, the Marten hardness HM of an aluminum alloy without addition of zirconium is shown in the bar on the left, in the bar on the right is the Martens hardness HM of an otherwise same alloy with the addition of 0.1 wt .-% zirconium is shown. 3 Overall, it shows that manganese - in particular at high cooling rates in thin-walled die casting - increases the 0.2% proof strength by solid solution strengthening of the aluminum dendrites, the indicator being especially the Marten hardness, which is measured by means of nanoindenter in the aluminum dendrites. 3b ) shows that this effect occurs particularly strongly by adding small amounts of zirconium. Table 1 cast state R _p0.2 / MPa R _m / MPa A5 /% α / ° Alloy 1 86 216 11.6 53.5 Alloy 2 92 214 8.8 53.2

Table 1 shows that zirconium addition also increases the strength at almost constant bending angle as a measure of ductility. Table 1 shows a comparison of the mechanical properties of example alloys in as-cast condition with and without zirconium. In this case, as alloy 1 in the table, an alloy with 5 wt .-% silicon, 0.5 wt .-% manganese, 0.15 wt .-% titanium and 0.15 wt .-% molybdenum, balance aluminum specified. This has a 0.2% proof stress R _p0.2 of 86 MPa, a tensile strength R _m of 216 MPa, an elongation at break A5 of 11.6% and a bending angle α of 53.5 °. As alloy 2 in Table 1 is given an alloy comprising 5% by weight of silicon, 0.5% by weight of manganese, 0.1% by weight of titanium, 0.15% by weight of molybdenum, and 0.1 Wt .-% zirconium, balance aluminum. This shows a 0.2% proof stress R _p0.2 of 92 MPa, a tensile strength R _m of 214 MPa, an elongation at break A5 of 8.8% and a bending angle α of 53.2 °.

Thus, it can be seen from Table 1, in particular, that by adding zirconium, a strength of the aluminum casting alloy can be increased at a virtually constant bending angle as a measure of the ductility.

Overall, it is found that with the aluminum casting alloy proposed here, the production method and the use of an aluminum casting alloy, a mechanically very favorable alloy can be provided which has its favorable mechanical properties already in the cast state without additional heat treatment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 03/006698 A1 [0002]
• EP 1612286 A2 [0003]
• DE 102008055928 A1 [0004]

Cited non-patent literature

• VDA 238-100 [0003]
• VDA 238-100 [0023]
• VDA 238-100 [0041]

Claims (10)

Aluminum casting alloy consisting of At least 4% by weight to at most 7% by weight of silicon, At least 0.5% by weight to at most 1.5% by weight of manganese, At least 0.03% by weight to at most 0.3% by weight of zirconium, - Other elements: each less than 0.3% by weight and in total not more than 1.2% by weight, - Rest aluminum. Cast aluminum alloy according to claim 1, characterized in that the aluminum casting alloy comprises at least 0.15 wt .-% to at most 0.3 wt .-% titanium. Cast aluminum alloy according to one of the preceding claims, characterized in that the aluminum casting alloy has at least 50 ppm to at most 300 ppm of strontium. Cast aluminum alloy according to one of the preceding claims, characterized in that the aluminum casting alloy at most 0.2 wt .-% iron, and / or at most 0.1 wt .-% magnesium, preferably at most 0.08 wt .-% magnesium , and / or at most 0.1 wt .-% copper, and / or at most 0.1 wt .-% zinc. Cast aluminum alloy according to one of the preceding claims, characterized in that the aluminum casting alloy at least 0.01 wt .-% to at most 0.15 wt .-% molybdenum, and / or at least 0.05 wt .-% to at most 0 , 15 wt .-% chromium. Solid cast aluminum alloy after casting according to one of the preceding claims, characterized in that the aluminum casting alloy has a 0.2% yield strength R _p0.2 greater than 80 MPa, preferably greater than 90 MPa, preferably greater than 100 MPa, a tensile strength R _m of greater than 180 MPa, an elongation at break A5 of greater than 8%, preferably greater than 10%, and / or a bending angle according to VDA 238-100 in the valid for the day of the present application Socket has greater than 40 °, preferably greater than 45 ° in the cast state without heat treatment. Cast aluminum alloy according to one of the preceding claims, characterized in that the manganese concentration of the aluminum casting alloy is tuned to a silicon and / or an iron concentration such that the strength of the aluminum casting alloy is increased, and / or such in that the aluminum casting alloy has fine-block, finely divided Al15 (Fe, Mn) 3Si2 phases Method for producing a component, in particular a motor vehicle component, from an aluminum casting alloy according to one of Claims 1 to 7, having the following steps: Melting the aluminum casting alloy of at least one master alloy and / or chemical elements, and - Cast the aluminum casting alloy at a minimum of 700 ° C to a maximum of 750 ° C in a mold. A method according to claim 8, characterized in that is dispensed with a heat treatment. Use of an aluminum casting alloy according to one of claims 1 to 7 for the production of a component in motor vehicle construction.

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