HK1245356A1 - Alloy for pressure die casting - Google Patents

Description

The invention relates to an aluminium-silicon die cast alloy, particularly for use in lightweight vehicle structural parts.

The alloy of the invention is designed to meet the increasingly high requirements for lightweight construction in the automotive industry. The use of a material with higher strength allows the designer to create structures with thinner walls and thus lighter weight.

Alloy of the AlSi10Mg or AlSi7Mg type is one of the most widely used casting alloys in industry.

The applicant claims that the Commission has not provided any evidence that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant has not been able to demonstrate that the applicant.

EP 1612286 B1 shows an AlSi alloy which already in the cast state, without further heat treatment, has high tensile strengths. This alloy allows for good tensile strength and tensile strength values for die cast parts in the cast state, so that the alloy is particularly suitable for the manufacture of safety components in the automotive industry.

EP0687742B1 also shows an aluminium-silicon based die casting alloy, which is used in particular for safety components in the automotive industry. Unlike the alloy from EP 1612286 B1, the resulting die castings are subjected to a heat treatment. In this alloy it was found that the increased strengths achieved are highly dependent on the magnesium content and this content can therefore be very well tolerated in the production.

Other known AlSi alloys are listed in EP 2 653 579 B1 and EP 2 735 621 A1 and both limit the iron content to a maximum of 0.2% by weight.

The objective of the present invention is to develop a high-strength aluminium die-cast alloy based on the alloy described in EP 0687742B1 with improved mechanical properties in terms of tensile strength, tensile strength and tensile strength, and with good moldable properties, no increased adhesive tendency, no increased risk of thermal cracking and no restrictions on the shape-filling ability.

Another task is to develop a high-strength aluminium die casting alloy with the above-mentioned properties, with an aluminium base of the alloy containing at least 50% of secondary metal (recycling material).

According to the invention, this task is solved by a die cast alloy based on aluminium silicon, consisting of: 8,5 to 11,5% by weight of silicon0,1 to 0,5% by weight of magnesium0,3 to 0,8% by weight of manganese0,02 to 0,5% by weight of iron0,005 to 0,5% by weight of zinc0,1 to 0,5% by weight of copper0,02 to 0,3% by weight of molybdenum0,02 to 0,3% by weight of zircon0,02 to 0,25% by weight of titanium3 to 50 ppm of boron10 to 200 ppm of gallium

Optionally 30 to 300 ppm Strontium or 5 to 30 ppm Sodium or 1 to 30 ppm Calcium for permanent refinement and 5 to 250 ppm Phosphorus and/or 0.02 to 0.25 weight per cent Titanium and 3 to 50 ppm Boron for grain refining and the remainder Aluminium and unavoidable impurities.

Other embodiments are given in the dependent claims.

In one embodiment, the alloy of the invention contains 0,15-0,5% by weight of iron.

In another embodiment, the alloy of the invention contains between 0.05 and 0.20 weight per cent molybdenum.

In another embodiment, the alloy of the invention contains 0.05% to 0.20% by weight of zircon.

In another embodiment, the alloy of the invention contains 60-120 ppm gallium.

In another embodiment, the alloy of the invention contains 0.3 to 0.5% by weight of manganese.

In another embodiment, the alloy of the invention contains 0.2 to 0.4% by weight of zinc.

In another embodiment, the alloy of the invention contains 0.15 to 0.25% by weight of copper.

In another embodiment, the alloy of the invention contains 8.5 to 10.0% by weight of silicon.

In another embodiment, the alloy of the invention contains 0.3 to 0.4% by weight of magnesium.

The die casting alloy according to the invention is used in the automotive industry to cast crash-relevant or strength-relevant structural parts.

The appropriate strength of an aluminium die cast alloy is achieved by a specific heat treatment, in addition to the choice of combination of alloy elements. The alloy of the invention is subjected to a T6 heat treatment, including solvent gels, air or water repellent and heat storage. It was found that high tensile strengths of just over 200 N/mm2 can be achieved compared to the alloy from EP 0687742B1.

The alloy of the invention is time-resistant after T6 heat treatment, i.e. no self-hardening occurs.

Furthermore, a T6 heat treatment at high flame temperatures of 530°C can achieve tensile strengths of up to 280 N/mm2 followed by water repellent.

In addition, the alloy of the invention may be subjected to a T7 heat treatment.

The alloy composition of the invention allows for improved tensile strength, tensile strength and tensile strength for die cast parts in the material state T6 or T7 respectively.

Compared with the alloy from EP 0687742B1, it was found that the choice of a copper content of 0.1 to 0.5% by weight, preferably 0.15 to 0.25% by weight, is responsible for improving the mechanical characteristics of the alloy. According to EP 0687742 B1, the addition of copper during the fusion process should be avoided, as copper has a negative effect on corrosion resistance. The composition of the alloy according to the invention was chosen in such a way as to avoid the formation of corrosion-promoting p-hases such as Al2Cu. Installation of a salt spray mist switch (ISO 9227) and an intercaloric stress test (ASTM G110-92) to overcome corrosion. A comparable corrosion resistance of the alloy was obtained, as was already the case with the EP12122861, already installed in the automobile.The addition of at least 0.08% zircon increases the tensile strength without reducing the strength of the material. This effect is achieved by a high melting phase. In this context, the time factor plays a special role. The size and strength of high melting phases always depend on the initial conditions. In the pressure coil, the melting usually begins already in the mold chamber, continues during the molding process and often ends in areas with a dilatant gel after the first part of the mold has been filled.The alloy of the invention has been developed for these processes, and only in the die casting process will the deposits have the right size and shape to show optimal material characteristics after a T6 heat treatment.

If molybdenum is added at the same time, these two elements work together and an additional increase in strength is obtained.

A similar effect was shown by the addition of gallium to the alloy of the invention, which, in addition to zircon and molybdenum, produced a finer structure, especially with a slightly increased iron content.

The addition of Mo, Zr and Ga plays a special role when recycled material, i.e. secondary aluminium, is used to manufacture the alloy. At 0.2% iron content, it is possible to minimize the damaging effect of iron on the fracture elongation.

The slightly increased iron content is compensated for by a reduction in the manganese content, otherwise there is a risk of sludge formation in the heat-resistant furnace on the casting machine.

The MnFe ratio also prevents the formation of so-called beta phases, i.e. plate-shaped AlMnFeSi secretions, which drastically reduce the ductility of the material.

The alpha-AlMnFeSi secretions are formed very finely in the alloy according to the invention by the addition of the elements Mo, Zr and Ga, so that their harmful effect on tensile strengths and corrosion tendency can be minimized.

The low percentage of zinc used in combination with the other elements of the invention has led to an improvement in moldable properties and an increase in the fracture strength. In general, a zinc content of up to 0.5% by weight does not yet have an effect on material properties.

The addition of strontium or sodium leads to a fine crystalline excretion of silicon, which results in the formation of a refined eutectic, and also has a positive effect on the strength and elongation of the alloy of the invention.

Preferably, a grain refining is carried out on the alloy according to the invention. The alloy can be preferably supplied with 1 to 30 ppm of phosphorus. Alternatively or additionally, the alloy for grain refining can also contain titanium and boron, with the addition of titanium and boron by means of a pre-alloy containing 1 to 2% by weight of Ti and 1 to 2% by weight of B, residual aluminium. Preferably, the aluminium pre-alloy contains 1.3 to 1.8% by weight of water and 1.3 to 1.8% by weight of Ti and has a Ti/B weight ratio of about 0.8 to 1.2%. The content of the pre-alloy in the alloy according to the invention is pre-set to 0.05 to 0.5%.

The studies have made it possible to produce the alloy of the invention with a recycling rate of 50-70%.

This requires high-quality recycled material such as scrap wheels, extrusion profiles, sheet metal and also splints and the use of a proven tip-drum furnace to melt the alloy.

The welding ability was verified in WIG welding tests, and in the stanzniet tests the alloy of the invention was crackproof despite its high strength.

Comparison example

The following comparisons are made between the compositions of an example alloy from EP0687742B1 (alloy 1) and two examples (alloys A and B) of the alloy of the invention. The data are given in grams. The mechanical properties (Rm, Rp0.2 and A5) of these two alloys were measured on 3 mm printed plates. Other

Results obtained

T6-Wärmebehandlung, Abschreckung an Luft

Legierung 1	236	167	7,9
Legierung A	288	209	11,0
Legierung B	280	189	9,6

T6-Wärmebehandlung, Abschreckung in Wasser

Legierung 1	326	241	7,9
Legierung A	332	257	10,0
Legierung B	348	264	8,2

Claims (11)

1. a width of not more than 50 mm, Other

   8,5% to 11,5% by weight of silicon

   0,1% to 0,5% by weight of magnesium

   0,3 to 0,8% by weight of manganese

   0,02 to 0,5% by weight of iron

   0,005 to 0,5% by weight of zinc

   0,1% or more but not more than 0,5% of copper

   0,02 to 0,3% by weight of molybdenum

   0,02 to 0,3% by weight of zircon

   10 to 200 ppm Gallium

   Other Other Other

   30 to 300 ppm Strontium or 5 to 30 ppm Sodium or 1 to 30 ppm Calcium for permanent purification and 5 to 250 ppm Phosphorus and/or 0,02 to 0,25 weight per cent Titanium and

   3 to 50 ppm boron for grain refining

   Other And the rest is aluminum and inevitable contaminants.
2. Pressure-moulded alloy according to claim 1, characterised by 0,15-0,5% by weight of iron.
3. Pressure-moulded alloy according to one of the above claims, characterised by 0,05 to 0,20% by weight of molybdenum.
4. Pressure-moulded alloy according to one of the above claims, characterised by 0,05 to 0,20% by weight of zircon.
5. Pressure-moulded alloy according to one of the above claims, characterised by 60-120 ppm gallium
6. Pressure-moulded alloy according to one of the above claims, characterised by 0.3 to 0.5% by weight of manganese.
7. Pressure-moulded alloy according to one of the above claims, characterised by 0.2 to 0.4% by weight of zinc.
8. Pressure-moulded alloy according to one of the above claims, characterised by a copper content of 0,15 to 0,25% by weight.
9. Pressure-moulded alloy according to one of the above claims, characterised by 8,5 to 10,0% by weight of silicon.
10. Pressure-moulded alloy according to one of the above claims, characterised by 0,3 to 0,4% by weight of magnesium.
11. Use of a die cast alloy according to one of the previous claims for die casting of crash or strength-relevant structural components in the automotive industry.