A Study of the Microstructure and Hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr by Laser Shock Peening

Abstract

In this paper, the microstructure and hardness of Ti-5Al-2Sn-2Zr-4Mo-4Cr titanium alloy with and without laser shock peening (LSP) were examined and compared. The titanium alloy samples were laser shock peened with different layers at the same power density. The microscopic structure after LSP are tested and analyzed by SEM and TEM. The results indicated that LSP changed the microstructure evidently. After 3 layers laser shock peening, there are nanocrystallization in the LSP zone. The shock wave provided high strain rate deformation and generated high-density dislocations in the material. Multiple severe plastic deformation caused by 3 to 5 LSP layers helped to rearrange the resultant dislocation, to form dislocation networks, leading to the formation of nanocrystallites. On the other hand, the microhardness across the polished surfaces of the titanium materials with and without LSP was measured. It is obvious that the laser shock peening improved the microhardness of the Ti-5Al-2Sn-2Zr-4Mo-4Cr for about 16% at the surface, and the affected depth is about 300 microns from the surface.

Effects of laser peening on fretting wear behaviour of alloy 718 fretted against two different counterbody materials

“…The induced plastic strain is accommodated by dislocation networks formed by rearrangement and annihilation of dislocations resulting in the formation of nanocrystallites. 32 Bugayev et al 33 have reported occurrence of nanocrystallization on the laser peened surface of alloy 600. Formation of nanocrystallites by laser peening has also been reported in aluminum alloy, 34 austenitic stainless steel, 35 Ti-6Al-4 V, 36 etc.…”