Effect of heat treatment on the tensile properties of Al-Li alloys

Al-Li alloy sheets are increasingly being used as autobody materials. The body in white (BIW) is a major contributor to the weight of the car. Hence considerable weight reduction can be achieved by using Al-Li alloy sheets for forming the body panels. Room temperature formability therefore becomes significant since large-scale production must be achieved. As Al-Li alloys acquire good amount of strength and hence dent resistance due to ageing, room temperature formability under different ageing conditions becomes important. To this end, tensile properties have been determined for three different solutionising temperatures, with three ageing times at each of the three ageing temperatures. Considerable influence of heat treatment on the mechanical properties, like strain hardening index (n), yield stress (YS), ultimate tensile stress (UTS) and percentage elongation to failure is observed. The investigations would throw light on not only the biaxial formability but also springback behaviour that is important in the BIW components. (C) 2004 Elsevier B.V. All rights reserved.