EFFECT OF WELDING AND POST WELD HEAT-TREATMENTS ON THE TENSILE AND FRACTURE-TOUGHNESS BEHAVIOR OF AL-MG-SI ALLOY

The effects of post weld T4 and T6 heat treatments (PWHT) on the tensile and fracture toughness properties of age-hardenable Al-Mg-Si (AA 6061) alloy weldments have been characterised; Fracture toughness behaviour of the welds was determined using J integral (J(IC)) and crack tip opening displacement (delta(IC)) measurements. The crack growth toughness values in terms of tearing modulus were also obtained from R curves. Microstructural and fractographic studies have been carried out to understand the fracture behaviour of the material. Post-weld solution treatment followed by natural ageing seems to impart optimum properties in terms df tensile strength, ductility and fracture toughness.