Reduction of residual stresses of fusion welded high-strength aluminum alloy joints by cold spraying

The high-strength AA2219aluminum alloy was successfully welded by variable polarity tungsten inert gas (VPTIG) welding, and the effect of cold spraying (CS) process on the residual stresses, microstructure and mechanical properties of the welded joints were investigated. The CS process being used for the welded joints was performed in different gas temperatures and pressures. The microstructure of the welded joints and coated joints were analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), while the residual stresses were measured by the blind-hole method. The results showed that the maximum residual tensile stress of the welded joint was located at the center of the weld. The residual stress decreased and then increased gradually from the center to base material, and then reached a maximum near the heat affected zone. After cold spraying treatment, the residual stress of the welded joint was significantly reduced by 25%-40% and distributed more uniformly. Besides, the microstructure and hardness of the upper surface of joints were also improved.