Recent development in aluminium alloys for the automotive industry

The growing demand for more fuel-efficient vehicles to reduce energy consumption and air pollution is a challenge for the automotive industry. The characteristic properties of aluminium, high strength stiffness to weight ratio, good formability, good corrosion resistance, and recycling potential make it the ideal candidate to replace heavier materials (steel or copper) in the car to respond to the weight reduction demand within the automotive industry. This paper summarises the recent developments covering aluminium's use in castings, extrusions and sheet; two specific examples will be given. The first deals with hang-on parts manufactured by Hoogovens Rolled Products Duffel, for which the weight saving potential can be 50%. Currently, the highly formable 5000 alloys are used mostly for inner panel applications, whilst the heat-treatable 6000 alloys are preferred for outer panel applications. This presentation reviews recent developments in aluminium alloys to improve formability, surface quality in both 5000 and 6000 alloys, and the bake hardening response of 6000 alloys. It also indicates the trend to develop a unialloy system to improve the aluminium scrap recycling. The second area deals with brazing sheet. Over the last 10 years there has been an increasing trend to replace copper heat exchangers with ones manufactured from brazed aluminium. Hoogovens Aluminium Walzprodukte Koblenz is one of the world's leading supplier of aluminium brazing sheet and is in the forefront of developing alloys with the combination of strength, formability, brazing performance and long life required by its customers. Materials have been development for both vacuum and controlled atmosphere brazing. The current status and future trends in aluminium brazing sheet for automotive applications will be presented. Particular emphasis has been placed on the development of long life alloys with superior corrosion performance over the more conventional materials. Using these two examples the technical and commercial aspects of the manufacturing processes of aluminium automotive components and engineering design support of materials producers are illustrated. The essential feature is the close co-operation at all stages between the material's supplier and the automotive manufacture. (C) 2000 Elsevier Science S.A. All rights reserved.