Experimental Study on the Effect of Cold Spraying on Residual Stress Relief and Mechanical Properties of Butt Weld

Cold spraying (CS) technology is a new low-temperature solid-state spray deposition technique. In this study, nickel-based alloy, cobalt-based alloy, and 316L alloy were deposited onto sandblasted butt weld surfaces via CS to prepare three CS specimens (WB-Ni, WB-Co, and WB-316L). Residual stress and hardness were measured for the CS specimens and unsprayed specimens (WB) to analyze the effect of CS on residual stress relief in butt welds. Static tensile tests and scanning electron microscopy (SEM) were conducted on all four specimen types to investigate the influence of CS treatment on the mechanical properties of welds. The underlying mechanisms of CS effects on residual stress and mechanical properties were analyzed at the microscale using SEM. Results show that CS significantly reduces welding-induced residual tensile stress, with greater elimination of longitudinal residual stress (σy) than transverse residual stress (σx). The difference between the two stress components is positively correlated with powder particle size. Among the three powders, 316L powder demonstrated the best performance in residual stress relief, eliminating 76.6% of transverse residual stress and 90.6% of longitudinal residual stress in the weld area. CS not only increases specimen hardness but also promotes a more uniform hardness distribution. Coating hardness is significantly higher than that of the substrate’s surface layer. The effectiveness of CS in enhancing surface hardness and relieving residual stress is negatively correlated with coating hardness. After CS treatment, the elastic modulus, yield strength, and tensile strength of the specimens increased by 18.69%, 8.14%, and 6.79%, respectively, while elongation after fracture decreased slightly by 1.43%.