A numerical investigation of the effect of support thickness and void ratio on thermal behavior and possible martensite decomposition in laser powder-bed fusion process

Abstract

Laser powder-bed fusion additive manufacturing process allows the production of complex parts. However, the thermal nature of the process involves spatially and rapidly changing heating-cooling cycles. This type of thermal process causes the formation of highly martensitic microstructures with poor ductility and crack resistance. To overcome this issue, a more lamellar structure for improved physical properties can be obtained either by an approach during production or by a post-production heat treatment. In this context, the support structure together with the substrate temperature are factors that can make a difference during production. If these two factors are properly determined by an assessment prior to production, martensite decomposition can be achieved In this study, the effect of the thickness and void ratio of a support structure with a constant cross-sectional area on the thermal behavior of the process was investigated numerically for the Ti6Al4V alloy. For this purpose, a case is examined for different void ratios and support thicknesses. As a result, it was predicted that the cases with a support thickness of 2 and 4 mm and a void ratio of 0.75 could initiate martensite decomposition.