An approach to improve the microstructure and mechanical properties: A hybrid manufacturing of laser directed energy deposition and shot peening

Abstract

As one of the most popular additive manufacturing technologies, laser directed energy deposition (LDED) has been extensively and deeply studied to improve the microstructure and properties of formed materials. Hybrid additive manufacturing(HAM) of LDED and shot peening is an innovative technology that combines the principle of surface strengthening and additive manufacturing. It can improve the mechanical properties and optimize the microstructure of the formed materials by strengthening the surface layer-by-layer. In this paper, the phase, oxygen content, microstructure, tensile properties, hardness and fracture morphology of the samples formed by LDED and HAM are compared. It is found that the mechanical properties of the forming samples are significantly improved by HAM, and the yield strength, ultimate tensile strength and average hardness are increased by 53%, 12% and 7%, respectively. Meanwhile, the microstructure of the sample is improved, some of the coarse columnar grains are refined, the heterogeneity of grain size is reduced, and the fibrous microstructure between layers is reduced. The hybrid additive manufacturing of LDED and shot peening can achieve high efficiency and high quality integrated manufacturing of forming parts, which is expected to promote its efficiency and applicability in practical cases in the future.