Effect of the Post-weld Heat Treatments on Mechanical and Corrosion Properties of Friction Stir-Welded AA 7075-T6 Aluminium Alloy

Abstract

Age hardenable, high-strength aluminium alloys are used majorly in aerospace, defence, marine and automobile components because of their excellent strength-to-weight ratio and better corrosion resistance. To join such nonferrous alloys, friction stir welding (FSW) is a special technique, which uses the phenomenon of friction and deformation while joining in the solid state. The joint sections of 2XXX, 6XXX and 7XXX series of aluminium alloys are susceptible to microstructural changes during FSW due to their ageing characteristics. These changes further aggravate the problem of mechanical engineering properties, and especially the corrosion resistance of these alloys. In the present work, focus is kept on the effect of post-weld heat treatments (PWHT) such as retrogression and re-ageing (RRA) and stabilization with double ageing (SDA) on mechanical properties, electrical conductivity and exfoliation corrosion resistance of AA 7075 aluminium alloy FSW joints.