Comparative investigation on microstructure and mechanical properties of GH4169 superalloy after laser shock peening with and without coating

To cater to the diverse requirements of industrial applications, it is crucial to conduct a comprehensive investigation into the influence of laser shock peening (LSP) with and without coating (LSPwC) on the microstructure and mechanical properties of materials. This study employs various methods to compare and analyze the effects of LSP and LSPwC on the microstructure and mechanical properties of GH4169 alloy. One notable contrast between LSP and LSPwC lies in the formation of oxide layers and microcracks on the surface of LSPwC-treated samples. Tensile tests subsequently reveal that LSP enhances the tensile strength, whereas LSPwC diminishes it. The reduced strength in LSPwC-treated samples can mostly be attributed to the oxide layer and microcracks resulting from laser-induced heat, as determined through failure analysis. After the removal of the oxide layer, the strength undergoes a significant improvement with LSPwC treatment, surpassing both the strength and ductility levels observed in GH4169 treated with LSP alone. These improvements can be attributed to a combined effect involving the removal of the oxide layer and microcracks, the formation of a gradient hardened layer, and the presence of dense slip bands.