Effect of cold drawing on the microstructure and property of precipitation strengthening Al-Mg-Si-Cu alloy prepared by continuous casting-extrusion

Contradictory relationship between strength and electrical conductivity for Al-Mg-Si-Cu series alloys is still an urgent issue to be solved. In this work, the influence of microstructural evolution on mechanical properties and electrical conductivity of the continuous casting-extrusion Al-Mg-Si-Cu alloy during heat treatment and cold drawing was investigated. The results showed that equiaxed grains were found in the alloy due to rapid cooling and frictional shear deformation during continuous casting-extrusion. Numerous dislocations, (3 ''/Q ' precipitates and GP zones were observed in the alloy after cold drawing. The strength of the alloy was enhanced by the interaction between dislocations and precipitates. In addition, with the increase in cross-section shrinkage ratio, the initial equiaxed grains in the alloy changed into elongated fiber grains along the drawing direction, which contributed to the improvement in both electrical conductivity and the strength of the alloy. Therefore, a good combination of strength and electrical conductivity was achieved in the alloy with a cross-section shrinkage ratio of 86.4%, i.e., the ultimate tensile strength of 320 MPa and electrical conductivity of 53.5% IACS, which was superior to the comprehensive performance of similar alloys. This work provides a strategy for obtaining high strength and high conductivity Al alloys via short process technology.