Effects of powder variation on the microstructure and tensile strength of Ti-6Al-4V parts fabricated by selective laser melting

Metallic powders are used as raw materials in the selective laser melting (SLM) process. These metal powders are typically available from more than one powder vendor. Even when powders have the same nominal chemical compositions, powders produced by different companies generally have different powder particle-size distributions and morphologies. These powder differences result in different powder-bed thermo-physical properties, that affect how the powder melts and solidifies. This paper studies the effect of powder variation on the microstructure and tensile strength of as-built SLM Ti-6Al-4V parts. Ti-6Al-4V powders from three different vendors were used to fabricate parts via SLM. Powder characteristics, such as particle-size distribution, morphology, and flowability, were evaluated. Powder-bed densities (PBD) and thermal conductivities were measured and compared. The microstructures and tensile strengths were investigated by standard metallographic and tensile-testing methods. Based on the experimental results, a correlation between the powder characteristics and part properties is discussed.