Microstructure and mechanical properties of spot welded Al–5·5Mg–0·3Cu alloy

AbstractThe influences of spot welding on the microstructure and mechanical properties of an Al–5·5Mg–O·3Cu alloy have been investigated. Results showed that dendrites were formed with porosity and cracks in the nugget. Grain boundary melting occurred in the heat affected zone and wide grain boundaries appeared. The alloy exhibited low hardness in the nugget centre. Tensile cracks propagated at the edge of the nugget and mixed rupture with dimples and intergranular fracture occurred. Fatigue fracture initiated at the edge of the nugget and propagated perpendicularly to the tensile axis. Transgranular fracture with striations was also observed.