Laser shock processing: An effective post-treatment process to enhance mechanical performances of laser additive manufactured parts

Laser additive manufacturing (LAM) is a novel manufacturing process that applied to fabricate the complex structures layer by layer according to a geometric model. Owing to its distinct advantages, it has been widely applied in various fields. However, the uncontrolled grain growth, tensile residual stresses, and near-surface voids and cracks are often introduced during part fabrication, all of which will limit the practical applications of LAMed components severely. Laser shock processing (LSP) is an advanced surface treatment technique capable of modifying near-surface microstructures and enhancing the mechanical properties of metallic materials by laser-generated stress effect. Therefore, employing LSP holds immense potential as a post-treatment process for LAMed parts. In this work, the basic principle of LSP was summarized in detail, and the performance enhancement mechanism of LAMed parts with LSP treatment was discussed in terms of residual stress, microhardness, tensile strength, fatigue performance, and wear resistance. In addition, the microstructural evolution induced by LSP treatment was analyzed as well, and the associated strengthening mechanisms are further elucidated. This work will provide an important reference value and guidance for researchers to further explore LSP mechanism and widen the adoption of LSP as an effective post-treatment method for LAMed parts.