PNNL

Abstract

The current study investigates the microstructural evolution of a dissimilar multiple-aluminum alloy stack (AA7055, AA7055, AA6022) produced by friction stir lap welding (FSLW). A through-thickness analyses of grain orientation map, grain size, strain distribution, and texture evolution by electron backscattered diffraction-based characterization technique were performed. Two different welding parameters were used to study the effects of the welding parameters on these microstructural characteristics. Our study shows that higher welding speed and higher rotation speed of the FSLW tool yield finer grains. The grain refinement and texture evolution were correlated with the recrystallization/restoration mechanism in the different regions for this complex stack. The mechanical property of the lap welded joints was presented in terms of microhardness distribution across the weld cross section