Influence of spot welding on fracture behaviour of Al-6 center dot 6Mg alloy

The influence of spot welding on the microstructure and fracture behaviour of an Al-6.6Mg alloy has been investigated. Results showed that dendrites w ere formed with porosity and cracks in the nugget. Grain boundary melting o ccurred in the heat affected zone and wide grain boundaries appeared. Spot welding increased the tendency towards intergranular fracture. Tensile shea r fracture was mixed with dimples and intergranular fracture. Fatigue fract ure was transgranular with striations at the surface. However, the alloy sh eet without welding showed dimpled tensile fracture and fatigue fracture mi xed with intergranular and transgranular fracture.