Microstructure and Mechanical Properties of Similar/Dissimilar Resistance Spot‐Welded Aluminum Alloys for Aerospace Applications

Abstract

2195 aluminum–lithium (Al–Li) and 2XXX series aluminum alloys are joined using resistance spot welding for the first time. The macrostructure, microstructure, element distribution, microhardness, and tensile‐shear property of spot‐welded joints are investigated. The microstructure of the fusion zone of 2195/2195, 2195/2219, and 2195/2A14 joints  is fine equiaxed spherical grains. It is found that solute segregation of Cu occurs in the grain boundaries in the fusion zone, forming Al2Cu. The microhardness shows that due to the dissolution of strengthening phase T1, the hardness of the fusion zone of the three types of joints is lower than that of the base material. The 2195/2195 joint has the best mechanical performance among the three combinations, with maximum tensile‐shear force and absorbed energy reaching 16893.7 N and 24.9 J, respectively. The fracture surfaces of all three types of joints exhibit mixed ductile‐brittle characteristics.