Laser shock peening combined with selective laser melting
Selective Laser Melting (SLM) is an additive manufacturing process in which the part is built layer by layer out of a metallic, ceramic or polymer powder. One of the biggest advantages of the SLM process is the ability to build parts with very complex geometries (lattice structures, conformal cooling channels, small features, etc.). One of the major limitations are the high tensile residual stresses (TRS) that accumulate during the building phase. These TRS lead to a decreased fatigue life of the part or can even cause layer delamination and failure during the building phase.
3D LSP is a process patented by LMTM, that combines Laser shock peening (LSP) with SLM, with the goal of decreasing TRS during the building phase and creating parts with tailored residual stress field, i.e. parts that have beneficial CRS in the near surface region.
In the figure below a clear change can be observed from the tensile behavior in the AB state (positive values of residual stresses), towards compressive stresses of parts treated with different LSP parameters (negative values of the RS) which leads to improved mechanical properties and increased fatigue life.
Residual stress profile of 316L samples made by SLM in the as-built state, and treated with LSP
(1mm spot size, without ablative coating)