Process-property relationships of Ti6Al4V fabricated through selective laser melting

Abstract

The selective laser melting (SLM) of TiAl6V4 has become an increasingly popular manufacturing option in the biomedical and aerospace fields, mainly due to its ability to create complex, net-shape parts within a short amount of time. To eventually incorporate additive manufacturing techniques like SLM into common manufacturing practice, it is imperative to ensure that the mechanical behaviour and performance of selective laser melted TiAl6V4 parts has the consistency of wrought material, especially for safety critical applications. This work explored the optimization of SLM machine parameters, such as laser power and laser scan speed in order to achieve maximum density. With optimized parameters, densities exceeding 99.5% were obtained for SLM parts. Afterwards, a series of post-SLM heat treatments were applied to tensile test specimens, to observe their effects on microstructure and mechanical properties. Through hot-isostatic-pressing (HIP), SLM yield strength values exceeded the wrought reference of 880 MPa. HIPed tensile specimens also surpassed the wrought reference for final elongation (14%) in many samples. As anisotropy in mechanical properties of SLM parts have been reported in previous works, crystal orientation and its effect on mechanical properties is discussed.