Effect of high energy shot peening on the microstructure and mechanical properties of Mg/Ti joints

The effects of high energy shot peening (HESP) on the microstructures and mechanical properties of tungsten inert gas (TIG) welded-brazed Mg/Ti joints were investigated, in terms of surface characteristics, residual stress variation, grain size, dislocation density and tensile strength of the resulting joints. The results show that HESP under an optimized Almen intensity of 0.16 mm N resulted in the surface defects elimination, high compressive residual stress, fine-grain strengthening and strain strengthening of Mg/Ti joint. All these factors contributed to the significant improvement in mechanical properties of the joints, leading to a notable enhancement (24.5%) in tensile strength of the Mg/Ti joint to 241 MPa over the joints without HESP treatment (193.5 MPa). However, further increment in Almen intensity to 0.24 mm N resulted in severe internal cracks within the joint, which deteriorated the mechanical properties of Mg/Ti joints.