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Effect of Laser Shock Processing on the Microstructure, Residual Stress and Wear-Fracture Behaviour of a Laser Deposited Fe-based Alloy Coating
A-M. Xiao, G-F. Sun, Z-P. Tong, S-Y. Dong, S-X. Yan, J-Z. Lu and Y-K. Zhang

A laser direct metal deposition (DMD) repaired Fe-based alloy coating was treated by laser shock processing (LSP). The effects of LSP on microstructure, phases, surface micro-hardness, surface residual stress and wear-fracture performance of the laser DMD repaired coating were investigated. Results showed that no obvious microstructure and surface microhardness differences are detected after LSP; however, LSP increased martensite volume fraction, decreased surface tensile residual stress and improved the wear and fracture performance of the repaired coating. The mechanism of the effect of LSP on the wear performance of the repaired coating was also addressed. In addition, the influence of the reduced residual tensile stress on the creation of debris was explained by referring to a mathematical model on the creation and propagation of the debris.

Keywords: Diode laser, Nd:YAG laser, Fe-based alloy, laser direct metal deposition (DMD), microstructure, residual stress, wear-fracture performance, laser shock processing (LSP)

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