High temperature aluminium alloy

Abstract

In an aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses the contents of the alloying elements magnesium and silicon in % w / w in a Cartesian coordinate system are limited by a polygon A with the coordinates [Mg; Si] [8.5; 2.7] [8.5; 4.7] [6.3; 2.7] [6.3; 3.4] and that the alloy also contains0.1 to 1% w / w manganesemax. 1% w / w ironmax. 3% w / w coppermax. 2% w / w nickelmax. 0.5% w / w chromiummax. 0.6% w / w cobaltmax. 0.2% w / w zincmax. 0.2% w / w titaniummax. 0.5% w / w zirconiummax. 0.008% w / w berylliummax. 0.5% w / w vanadiumas well as aluminium remainder rest with further elements and manufacturing-related impurities of individually max. 0.05% w / w and max. 0.2% w / w in total.The alloy is suitable in particular for the production of cylinder crankcases by the pressure die casting method.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to an aluminium alloy of type AlMgSi with good creep strength at elevated temperatures for the production of castings subject to high thermal and mechanical stresses.[0003]2. Description of the Prior Art[0004]The further development of diesel engines with the aim of achieving an improved combustion of the diesel fuel and a higher specific output leads inter alia to a higher explosion pressure and in consequence to a pulsating mechanical load acting on the cylinder crankcase that makes very high demands on the material. Apart from a high fatigue strength, a good endurance strength at high temperatures of the material is a further precondition for its use in the production of cylinder crankcases.[0005]AlSi alloys are generally used today for components subject to high thermal stresses, this high-temperature strength being achieved by the addition of Cu to the alloy. Copper does, however, also increas...

AI Technical Summary

Benefits of technology

[0017]The alloying elements Mn and Fe allow sticking of the castings to the mould to be avoided. A higher iron content results in a higher high-temperature strength at the expense of reduced elongation. Mn contributes also significantly to red hardness. Depending on the field of application, the alloying elements Fe and Mn are therefore preferably balanced with one another as follows:With a content of 0.4 to 1% w / w Fe, in particular 0.5 to 0.7% w / w Fe, a content of 0.1 to 0.5% w / w Mn, in particular 0.3 to 0.5% w / w Mn, is set.With a content of max. 0.2% w / w Fe, in particular max. 0.15% w / w Fe, a content of 0.5 to 1% w / w Mn, in particular 0.5 to 0.8% w / w Mn, is set.

[0020]Copper results in an additional increase in strength, but with increasing contents leads to a deterioration in the corrosion behaviour of the alloy.

[0021]The addition of cobalt allows the demoulding behaviour of the alloy to be further improved.

[0022]Titanium and zirconium improve the grain refinement. A good grain refinement contributes significantly to an improvement in the casting properties and mechanical properties.

[0023]Beryllium in combination with vanadium reduces the formation of dross. With an addition of 0.02 to 0.15% w / w V, preferably 0.02 to 0.08% w / w V, in particular 0.02 to 0.05% w / w V, less than 60 ppm Be are sufficient.

Problems solved by technology

Copper does, however, also increase the hot shortness and has a negative effect on the castability.

Images