Surface layer microstructures and wear properties modifications of Mg-8Gd-3Y alloy treated by shot peening

Highlights: • Shot peening refined grains and induced compressive residual stress in the surface layer. • Nanograins were formed when the peening intensity reached 0.46 mmN. • Hardness and wear properties increase as the peening intensity increases. • Hardness, ductility, residual stress and surface roughness should be responsible for wear properties of peened Mg alloys. -- Abstract: Shot peening effects on the microstructure, residual stress and wear properties of Mg-8Gd-3Y alloy were systematically studied. The results showed that the grain sizes were greatly refined and high-level dislocations were induced in the deformation layer. The grain size decreased with increasing the peening intensity, and nanograins were obtained when the peening intensity reached 0.46 mmN. The formation of nanograins was mainly attributed to the activity of dislocations and occurrence of dynamic rotation recrystallization. In parallel, compressive residual stress was developed in the deformation layer, the maximum magnitude of which reached −174 MPa under the peening intensity of 0.46 mmN. Additionally, owing to the modification of microstructures and the introduction of compressive residual stress after shot peening, the microhardness and wear resistance of Mg-8Gd-3Y alloy were promoted prominently. In comparison with the untreated counterpart, the average wear volumes of the peened ones were decreased by 9.47%, 36.26% and 40.70% corresponding to 0.13, 0.23, 0.46 mmN, respectively. Therefore, it is concluded that SP can be considered as a promising technology to improve the surface microstructures and wear properties of Mg-8Gd-3Y alloy.