Study on ductile fracture of unweldable spray formed 7055 aluminum alloy TIG welded joints with ceramic particles

Abstract Spray formed 7055 high strength aluminum alloy welded joint with traditional aluminum alloy welding wires has low strength, only 240–260 MPa, and high brittleness, which seriously restricts the widespread application of spray formed 7055 high strength aluminum alloy. In this paper, two kinds of aluminum alloy welding wires containing TiB2 and ZrB2 ceramic particles were developed, and TiB2 and ZrB2 ceramic particles were introduced into the welded joint of the spray formed 7055 aluminum alloy by TIG welding, respectively. The results show that the microstructures of TiB2-7055 welded joint is fine equiaxed grains, and the tensile strength of is 310 MPa, reaching 51.6% strength of the base metal. Moreover, the elongation is more than 5%, demonstrating ductile fracture. The microstructure of ZrB2-7055 welded joint is fine dendrite, and the tensile strength is 280 MPa, reaching 46.6% strength of the base metal, showing brittle fracture. The development of this new type of welding wire containing TiB2 ceramic particles can solve the problems of softening and low plasticity of spray formed 7055 high strength aluminum alloy fusion welded joint, and provide the basis for expanding the applications of spray formed 7055 high strength aluminum alloy in the fields requiring both lightweight and high strength.