Microstructural study and mechanical characterisation of heat-treated direct metal laser sintered Ti6Al4V for biomedical applications

Direct metal laser sintering (DMLS) of Ti6Al4V is being widely used to manufacture biomedical implants. The rapid solidification process can result in undesired microstructure that imparts poor ductility and end up residual stresses. An optimum heat treatment minimizes distortion and enables a desirable microstructure. In this work, we have examined the efficacy of heat treatment in vacuum and in air, at 800°C and 1100°C. There were minimal differences in the microstructure and mechanical properties when heat treated in air or vacuum, at 800°C. Heat treatment at 1100°C was feasible in vacuum but not in air. Comparisons were made with two-layer thicknesses (30 and 50mm) to enable higher productivity. These results were validated using a cranial implant. Thus, it may be possible to do heat treatment in air at 800°C for DMLS Ti6Al4V thereby enabling manufacturing of implants by DMLS process in a timely and cost-effective manner.