Improving the microstructure of high speed selective laser melted Ti6A14V components by varying residence time during heat treatment

Abstract

Selective laser melting (SLM) is a powder bed additive manufacturing technique that produces components layerby-layer from computer aided designs as opposed to conventional manufacturing methods. Although this manufacturing technique offers various advantages, the microstructure of the produced components exhibits an acicular martensitic a’ phase which exhibits low ductility and high hardness on the produced components. Heat treatment is known to improve the microstructure and ductility and hardness of SLM produced Ti6Al4V components. This study reports on the effect of residence time during heat treatment of Ti6Al4V samples that were built with Aeroswift 3D printing SLM machine. Samples were heat treated to a temperature of 1000°C and held for 2hrs, 4hrs, 8hrs, 10hrs and 12hrs before furnace cooling. It was found that the microstructure transformed from martensitic to lamella a+ß, then to globular a+ß as residence time was increased. Furthermore, grain growth was observed with an increase in residence time.