Excellent Strength-Ductility-Corrosion Resistance Combination of Li Micro-alloying and Severe Plastic Deformation of Al-Cu-Mg Alloy

This study investigated the effect of severe plastic deformation induced by friction stir back extrusion on microstructure, mechanical properties, and corrosion resistance of Al-Cu-Mg alloy containing 0.5 wt.% of lithium micro-alloy and Cu/Mg ratio of 3.8. The effect of the rotational speed of friction stir back extrusion in the range of 600-1200 rpm in the constant traverse speed of 20 mm/min was studied. The results show that the size of equiaxed grains formed during the friction stir back extrusion process due to dynamic recrystallization increases from 21.0 & PLUSMN; 2.3 to 29.6 & PLUSMN; 4.5 & mu;m by enhancing rotational speed from 800 to 1200 rpm. The dominance of the temperature effect on the plastic strain on the surface of wires during the friction stir back extrusion process results in the formation of coarser grains at the surface of wires. Friction stir back extrusion by a rotational speed of 800 rpm and a traverse speed of 20 mm/min result in the maximum yield, tensile strength, and minimum corrosion rate of 353.56 & PLUSMN; 10.31, 509.91 & PLUSMN; 11.56 MPa, and 0.008 mm/year, respectively. The friction stir back extrusion process has increased at least 23, 39, and 29% in yield strength, ultimate tensile strength, and elongation compared to as-cast alloy.