Investigation on reducing residual stress and optimizing performance of 2219 aluminum alloy friction stir welded joint by cold spraying

In this paper, the cold spraying (CS) was applied on friction stir welded 2219 aluminum alloy joint to reduce its residual stress. The correlation between the process parameters of CS and residual stress and mechanical properties was studied. Results reveal that the grain size of cold sprayed joints is significantly refined comparing to that of the welded joints, meanwhile the content of high angle grain boundaries and recrystallized grains increases. Cu powder has the best effect on enhancing the mechanical properties of joint. With the increase of gas pressure, the residual stress is decreased. The optimal powder type, gas pressure and gas temperature of CS are Cu powder, 3 MPa and 400 degrees C, respectively. The maximum residual stress is reduced from a tensile stress of 159 MPa in the welded joint to a compressive stress of -17.4 MPa in cold sprayed joint, and the tensile strength and elongation are further increased to 331 MPa and 4.6 %, respectively.