A combined DEM-FEM numerical method for Shot Peening parameter optimisation

Uniformity of residual stress distribution on the surface of S30432 austenitic stainless steel by different shot peening processes

Characterization and analyses on micro-hardness, residual stress and microstructure in laser cladding coating of 316L stainless steel subjected to massive LSP treatment

The objective of the present study was to examine the influence of laser peening without protective coating (LPwC) process on surface mechanical properties of precipitation hardened stainless steel 17-4 PH. Pulse densities, 2500 and 6250 pulses cm−2, using a constant laser power density of 5.97 GW cm−2 were chosen and their effect on residual stresses, micro-structure, micro-hardness, surface roughness and topography were investigated. Higher pulse density induced large compressive residual stresses and influenced up to depth of 600 μm. It was confirmed from resulted larger lattice strain in LPwC processed 17-4 PH steel with higher pulse density. No phase transformation and microstructural change were observed, which represented pure mechanical effect of LPwC. Hardness was increased with depth of hardened layer up to 600 μm for higher pulse density. However, the surface roughness was increased by the process, and resulted in more pronounced peening pattern. Surface topography revealed columnar structure after LPwC process.

Surface modification of 17-4 PH stainless steel by laser peening without protective coating process

Fatigue is a dominant failure mechanism of several engineering components. One technique for increasing the fatigue life is by inducing surface residual stress to inhibit crack initiation. In this review, a microstructural study under various bulk (such as severe plastic deformation) and surface mechanical treatments is detailed. The effect of individual microstructural feature, residual stress, and strain hardening on mechanical properties and fatigue crack mechanisms are discussed in detail with a focus on nickel-based superalloys. Attention is given to the gradient microstructure and interface boundary behavior for the mechanical performance. It is recommended that hybrid processes, such as shot peening (SP) followed by deep cold rolling (DCR), could enhance fatigue life. The technical and scientific understanding of microstructural features delineated here could be useful for developing materials for fatigue performance.

Xiaoyan Gan

Papers

Influence of shot peening on the fatigue life of laser hardened 17-4PH steel