Effect of Laser Remelting on Microstructure, Residual Stress, and Mechanical Property of Selective Laser Melting-Processed Ti-6Al-4V Alloy

Abstract

Laser remelting is often used during selective laser melting (SLM) processes to restrain the residual stress and improve the mechanical strength of the products. However, researches regarding its effects on porous metals with trabecular or thin-walled structure are still quite lacking. Hereby, remelting treatments have been employed during the SLM processes of a porous Ti-6Al-4V alloy in this study and their influences on dimensional accuracy, microstructure, mechanical property, and residual stress were researched. The results indicate that remelting treatments can provide a stronger bonding condition for the cellular structure, and improve the yield strength and elastic modulus of the alloy. Rescanning with 75% energy density results in 33.5–38.0% reduction of residual stress. In terms of pore structure and morphology, the porosities of remelted specimens are 2–4% lower than that of single-scanned specimens. This inconsistency increases with the increase of sheet thickness. It is suggested that the rescan laser power should be turned down during the preparation of porous titanium with thick cell walls to ensure dimensional accuracy.