Influence of Shot Peening on the Elemental Diffusion and Properties of Wide-Gap Brazed Joints

Based on the surface shot peening treatment of Hastelloy X, this study investigated the impact of shot peening on the interfacial element diffusion and properties of wide-gap brazing joints. The microstructure and mechanical properties of wide-gap brazing joints obtained from Hastelloy X surfaces without shot peening and those treated with shot peening using ball sizes of 0.180, 0.300, and 0.500 mm were compared. SEM and EDS were used to analyze the diffusion layer structure and element distribution characteristics. The results indicate that the grain refinement effect from shot peening strengthening treatment promotes the diffusion of the melting-reducing element Si in Hastelloy X. When the shot size is 0.300 mm, the diffusion coefficient of Si in the brazing joint structure is the highest of 1.83×10-8 mm2·s-1; at this time, the diffusion layer is the thickest of 224.97 μm in thickness; the interface shear strength of the wide-gap brazing joint is the greatest of 543.38 MPa, which shows a 19.39% increase compared to that of the non-shot-peened sample. Additionally, theoretical calculations were conducted to determine the impact of different grain sizes under three shot peening processes on the diffusion coefficient of Si element. Theoretical calculations are combined with experimental data to elucidate the diffusion mechanism of Si in the microstructure of wide-gap brazing joints.