DEVELOPMENT OF AN ALUMINUM SHEET ALLOY WITH IMPROVED FORMABILITY

Aluminum auto-body sheet alloys with enhanced formability have been developed in the Al-Mn-Mg-Si system. The improvement in formability is due to a fine grain size, a precise control of solute elements (especially Si), and virtual elimination of coarse second-phase particles. These refined features, achieved in part from the use of a high casting cooling rate, result in a fine deformed dislocation substructure which resists strain localization. The absence of coarse particles delays final fracture. The experimental alloys had a positive strain-rate sensitivity which is not normally observed in alloys containing Mg. © 1990 The Metallurgical of Society of AIME.