Analysis of plastic instability in commercially pure Al alloys

The present work deals with sequences of rolling-shear experiments conducte d on an Al 1050 alloy. Particular attention was paid to the transient mecha nisms produced by a change of loading mode. It is shown that the flow behav iour during shearing strongly depends on the amplitude in the strain path c hange. More precisely, plastic instabilities take place just after yielding only for shear tests performed at some definite orientations from the roll ing direction. It is shown that such a mechanical anisotropy is related to the deformation texture. The texture evolution is evaluated through self-co nsistent calculations. Flow softening is obtained when the Taylor factor, e stimated with the model, decreases. (C) 2000 Elsevier Science S.A. All righ ts reserved.