INFLUENCE OF MICROSTRUCTURAL FEATURES ON THE FORMABILITY OF ALUMINIUM ALLOYS.
Abstract
The formability of some aluminum sheet alloys is discussed in terms of the elements in solid solution, constituent and dispersoid particles, age-hardening precipitates and grain and cell boundaries. The importance of the influence of these components on the mode of deformation is emphasized. Microstructural features that support continued general plasticity and those that increase the tendency toward strain localization and fracture events are considered for both heat treatable (AlCuMg, AlMgSi) and strain hardening (AlFeSi, AlMn(Mg)) alloys. The occurrence of unstable deformation during forming is promoted by high levels of prior deformation and changes in the deformation mode, e. g. form cold rolling to deep drawing. A metallographic technique useful for the investigation of failure initiation is also presented. This involves gallium embrittlement.