EXPERIMENTAL-ANALYSIS OF ALUMINUM YIELD SURFACE FOR BINARY AL-MG ALLOY SHEET SAMPLES

In this work, the yield surfaces of binary aluminum-magnesium alloy sh eet samples were measured using biaxial compression tests. Sheet sampl es of a given material were stacked and bonded together with epoxy and cubic compression specimens were machined out of the laminate. The yi elding behavior was assumed to be independent of the hydrostatic press ure. In the analysis of the biaxial compression tests, the effects of friction and of the elasticity of the die were accounted for. These ef fects were studied with the aid of finite element method (FEM) simulat ions of the test which proved to be useful in avoiding systematic erro rs. The yield surfaces of three binary alloy sheet samples containing 5wt% Mg but with different crystallographic textures were analyzed. Th e different textures resulted from processing under different thermome chanical conditions. The experimental yield surfaces were compared to predictions made with the Taylor-Bishop and Kill (TBH) model and with a phenomenological yield function. The experimental and polycrystal yi eld surfaces were found to be in fair agreement. The yield function wa s found to be a suitable description of the plastic behavio for only t wo of the materials studied. (C) 1998 Elsevier Science Ltd. All rights reserved.