Impact of Laser Shock Peening on Mechanical Properties of Wire Arc Additive Manufactured Grade 91 Steel and Monel-400 Bimetallic Components

This study investigates the effects of Laser Shock Peening (LSP) on the mechanical properties and microstructure of Wire Arc Additive Manufactured (WAAM) bimetallic components made of Grade 91 Steel and Monel-400. LSP, a surface enhancement technique, was applied to address the residual stress and enhance the mechanical performance of these bimetallic components. Electron Backscatter Diffraction (EBSD) analysis post-LSP showed refined grain structures, contributing to the observed enhancements in mechanical properties. The research revealed that LSP treatment increased the tensile residual stress at the bimetallic interface from 109 ± 2.5 MPa to 185.9 ± 2.5 MPa, indicating a strengthening of the bimetallic interface. The tensile strength of the Grade 91 Steel part increased from 1140 ± 6.5 MPa to 1280 ± 4.5 MPa after LSP, while the Monel-400 section showed a slight decrease in tensile strength from 516 ± 2.5 MPa to 511 ± 6 MPa but an increase in elongation from 31 to 38.5%. Furthermore, microhardness at the interface improved, with a rise from 267 ± 3 HV0.1 to 303 ± 4 HV0.1 post-LSP. The enhanced properties of the bimetallic components are particularly beneficial for applications in the petrochemical and marine industries, where the combined resistance to thermal and corrosive environments is critical. This study provides a new understanding of the application of LSP in improving the mechanical properties of WAAM-produced bimetallic components.