Fracture behaviour of high strength unworked Al alloys

Abstract In this investigation attention was focused on the fracture behaviour of some high strength aluminium alloys in the as-cast and heat treated condition. Fracture is initiated in constituent particles located at grain or dendrite boundaries, and propagates in an intergranular manner. Crack initiation occurs independently of temper condition at a critical stress of about 1000 MN m−2. Fracture toughness varies between 17 and 25 MN m−3/2 depending upon aging condition. The measured toughness can be explained in terms of the critical decohesion stress, the yield stress, and the volume (or distance) over which the critical decohesion stress is exceeded.