Selective laser melting (SLM) is an attractive technology for fabricating complex metal parts with reduced number of processing steps compared to traditional manufacturing technologies. The main challenge in its adoption is the variability in mechanical property produced through this process. Control and understanding of microstructural features affected by the SLM process is the key for achieving desirable mechanical properties. Numerous studies have been published related to microstructure and mechanical properties of SLM printed parts; however, few of those reported end-to-end process–structure–property relationship. Therefore, the current study aims to comprehensively present the widespread microstructure information available on SLM processed Ti6Al4V alloy. Furthermore, its effects on the magnitude and anisotropy of the resultant mechanical properties, such as the yield strength and elongation, has been established. A Hall–Petch relationship is established between α lath size and yield strength magnitude for the as-built, heat-treated, transverse, and longitudinal built samples. The anisotropy in flow stress is established using the α lath size and prior β grain orientation. Percentage elongation was identified to be affected by both α lath size and powder layer thickness, due to its correlation with the prior β columnar grain size. A linear relationship was established between percentage elongation and combined size of α lath and powder layer thickness using the rule of mixtures.

The current study is targeted towards topologically optimizing structures using thermal compliance for manufacturability in Powder Bed Fusion Additive Manufacturing machines. The optimization has been carried out using location-specific thermal conductivity varying as a function of powder-bed and solidified material states. Two formulations, namely, parallel and series thermal resistance, have been formulated and studied to take the effect of state-based location-specific thermal conductivity in Topology Optimization. The density distributions arising from the parallel thermal resistance formulation are similar to the density distributions that occur, assuming no powder bed-based effects. The series thermal resistance formulation led to density distributions that involved broadening of low density distributions around highly dense topologically optimized structures. The series thermal resistance formulation framework can maintain a constant heat flow by broadening the low-density distributions, thereby capturing the effect of location-specific thermal conductivity. In addition, the effect of penalty factor has been studied. Using the parallel thermal resistance formulation, an increase in the number density of low density branches around the highly dense topologically optimized structures have been observed. The series thermal resistance formulation led to increased broadening of low density distributions in space around its denser counterparts.