Abstract
Selective laser melting（SLM）, one of powder bed fusion（PBF）-type additive manufacturing（AM）processes, is a promising technology that enables high accuracy production of arbitrary structures; therefore, it had been utilized in aerospace and medical fields. However, there are many un-elucidated phenomena which will largely affect the quality of products. Spatter generation, in particular, has been reported to adversely affect the stability of fabrication, resulting in impaired performance of the products. The suppression of spatter generation is indispensable for acquiring high quality products. However, there are many unknown controlling factors about the basis of spatter generation. In this article, we aimed to elucidate the influence of atmosphere gas on spatter generation during laser irradiation on Ti-6Al-4V powder, in particular, the effect of oxygen concentration in inert gas. The amount of spatter generation increased with the oxygen concentration in the atmosphere, and the oxygen content in the spatter particles also increased. The diameter of spatter particles increases remarkably compared with the raw powder particles, which lead to not only inhomogeneous powder bed when the spatter particles fall down on the fabricating products, but also to an unexpected increase in the oxygen concentration of products closely relating to the mechanical property. Impurity oxygen in the atmosphere gas should be eliminated during SLM process.
