PROGRESS IN DUCTILE ALUMINIUM HIGH PRESSURE DIE CASTING ALLOYS FOR THE AUTOMOTIVE INDUSTRY

Abstract

Today the die casting process is used to cast parts with high quality requirements such as engine cradles, cross members and nodes for space frame construction. This has presented the challenge to design alloys with superior mechanical properties. For crash relevant parts requiring high ductility (elongation > 12 %) one option to meet these properties is by heat treating a low iron Al-Si alloy to a T4 or T7 temper. However heat treatment can lead to part distortion and blistering resulting in higher costs for the producer. The second option is Al-Mg alloys type which fulfill these requirements in the as-cast state but the alloys are not easy to cast. Research was started using the easy to cast Al-Si alloy system targeting a high elongation (> 12 %) and yield-strength (> 120 MPa) already in temper F and not showing any long term aging behavior. This paper will discuss the technical progress which began in the early 1990ies, gaining in importance with the first series space frame Aluminum car, continuing with structural parts applied in the as-cast state and approaching a future with an increasing amount of light weight components replacing steel and heat treated Aluminum designs.