base metal

friction stir welding

welded joints

rotational speed

friction stir processing

friction stir welded

stir welding

stir zone

heat input

welding speed

International Journal of Fatigue

This paper studied the microstructural and mechanical evolution of friction stir welded (FSW) 6061-T6 aluminum alloy, the influence of notch locations on impact and fatigue crack growth (FCG) behavior were evaluated. The results show that the grain size, hardness and impact absorbing energy of weld nugget zone (WNZ) was smaller than those of base material and heat affected zone. Longitudinal residual stresses dominated all the zones of the joint, FSW induced compressive stresses in WNZ. The particles in aluminum alloy matrix can impede the propagation of fatigue crack. The microstructural inhomogeneity and crack closure contribute to the fluctuation FCG rate.

Microstructure, mechanical properties and fatigue crack growth behavior of friction stir welded joint of 6061-T6 aluminum alloy