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The effects of massive laser shock peening (LSP) treatment with different pulse energies on surface roughness and microstructural evolution in the surface layer of AISI304 stainless steel were investigated. The deformation-induced grain subdivision processes under two LSP treatment conditions of 3 and 6 J pulse energies were characterized and presented, respectively. Subsequently, EBSD characterization was conducted to analyze the peaks of misorientation angle for as-machined sample and LSPed samples with different pulse energies. Furthermore, a novel MT-MT intersection with four directions was found for the first time in the plastic deformation layer of AISI304 stainless steel, and the generation mechanism was completely presented according to the inherited crystal structure of austenite stainless steel. The formation process of the surface roughness and the formed microstructure subjected to massive LSP impact treatment with different pulse energies were compared and revealed.

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The effects of coverage layer and temperature on the tensile properties and surface microstructure of H62 brass subjected to laser shock peening (LSP) were systematically investigated. Ultimate tensile strength, elongation rate, and in-depth microstructural evolutions of three kinds of LSPed specimens, including LSPed specimens with one coverage layer and three coverage layers at room temperature, and one coverage layer at dynamic strain aging temperature, were subsequently measured and characterized. Special attentions were paid to surface nanocrystallization and amorphization of H62 brass subjected to room-temperature LSP and warm LSP technologies for the first time. The formation mechanisms of surface nanocrystallization and amorphization induced by room-temperature LSP and warm LSP were also discussed and completely revealed, and surface nanocrystallization contributed to the improvement of ultimate tensile strength and elongation rate of H62 brass subjected to LSP.