Effect of high energy shot-peening on the microstructure and mechanical properties of Al5052/Ti6Al4V lap joints

摘要

Severe plastic deformation led to surface grain refinement when treated using high energy shot-peening (HESP); the average grain size was similar to 20-30 mu m in the top, which was similar to 10% of the unpeened ones. The broken Si (Al-Si) particles refined by HESP were important in dislocation multiplication and movement to facilitate the surface modifications. After HESP, residual compressive stress along the hardened layer was induced in the surface of the seam. The highest residual stress along the surface reached similar to 200 MPa and the maximum along thickness occurred in sub-surface region. Microhardness values decreased as the distance increased through thickness. At peening pressures of 0.3 and 0.4 MPa, the average tensile shear strength of the joint remained at 195 MPa, which was equivalent to similar to 90% that of the base Al alloy. The cracks and pores in the surface were eliminated and a fracture was located in the base Al alloy.