Influences of scanning speed and short-time heat treatment on fundamental properties of Ti-6Al-4V alloy produced by EBM method

This study was conducted to examine the influence of the scanning speed of an electron beam on the fundamental properties of Ti-6Al-4V alloy produced by EBM (electron beam melting) method. We further investigated the effect of short-time heat treatment on those properties. By increasing the scanning speed, the desired outer shape was more closely achieved. However, molding defects became larger and the density reduced. On balance, the appropriate range of scanning speed was between 1 and 2 m/s. EBM materials had columnar microstructures elongated in the building direction. Although these characteristic microstructures were mainly composed of the stable α and β phases, the α' phase was partially generated at high scanning speed. By increasing the scanning speed, the amount of the α' phase increased and the hardness rose. The short-time heat treatment generated the fine α' and α phases in the prior β phase. This microstructural change markedly increased the hardness of EBM material.