Improving the casting properties of high-strength aluminium alloys

• Published in: Materials and Technology Vol. 38; no. 1-2; pp. 99 - 102
• Main Authors: Vojtech, D, Serak, J, Ekrt, O
• Format: Journal Article
• Language: Slovenian
• Published: 01.01.2004
• ISSN: 1580-2949

Al-Zn-Mg-Cu alloys are examples of high-strength alloys. After age hardening they often possess tensile strengths of more than 500 MPa. However, their casting properties are relatively poor as a result of solidification intervals that are too wide. Therefore, they often require an extrusion, rolling, or forging treatment, and the production of small series of special parts can, as a consequence, be very expensive. In this study, an improvement in the castability and a reduction of the hot-tearing tendency was achieved by adding small amounts of appropriate elements (Ni, Mg and Si), which form a quasi-eutectic microstructure to reduce the solidification interval of the Al-Zn-Mg-Cu alloys. This improvement is demonstrated by a comparison of the casting properties of the quasi-eutectic Al Zn-Mg-Cu-Ni-Si alloy with the AlZn7Mg2Cu1 and AISi10 alloys. In addition, an appropriate heat-treatment procedure, which ensures the optimum mechanical properties, is described.