Effect of Laser Shock Peening (LSP) on the Phase Evolution, Residual Stress and Hardness of Hastelloy-X Superalloys
S. Nath, P. Shukla, X-J. Shen And J. Lawrence
Efforts have been made to understand the effect of laser shock peening (LSP) on the phase, residual stress and hardness of Hastelloy-X superalloys. A 10 J Nd:YAG laser was used for the LSP operation. Following LSP detailed microstructural and phase analysis along with residual stress and hardness studies were undertaken. A parametric window was first established to explore the relationship between LSP process parameters and the respective surface and bulk properties. The effects of an absorptive layer on the properties of the modified layer were also investigated. Qualitative and quantitative information on dislocation density was obtained using X-ray diffraction (XRD) analysis and correlated with the processing parameters. Residual stress developed following LSP was measured using the XRD technique. An increase in the hardness of the Ni-based superalloys was observed. The residual stress on the surface of the laser shock peened Hastelloy-X superalloy showed a maximum compressive stress of 166 MPa. A detailed microstructure-property relationship was established to understand the mechanism of property enhancement. Further optimization of the LSP process to surface treat the Hastelloy-X superalloys will open up new avenues for the material’s applicability, particularly in the aerospace sector.
Keywords: Nd:YAG laser, Hastelloy-X, superalloy, absorptive layer, laser shock peening (LSP), residual stress, Hugoniot elastic limit (HEL), hardness; microstrain, dislocation density