Investigation of Microstructure and Mechanical Properties of STS 316L Powder According to Humidity in the DED Process

Additive manufacturing (AM) technology has been experiencing high growth in recent years to produce a variety of metals and alloys. In such additive manufacturing, the storage condition of the powder affects the flowability of the powder and the microstructure and mechanical properties after the additive manufacturing process. In this study, in order to determine the difference depending on the humidity of the powder, STS 316L powder was dried at 60°C for 24 hours and then immediately subjected to the DED process. In addition, STS 316L powder was heat treated for 24 hours at 5%, 35%, 50% and 70% RH, respectively, and then DED. The process was carried out and classified into four conditions. Powder phase composition and morphology classified according to each condition were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM). The moisture content of the powder was also measured, and flowability was evaluated using Avalanche Energy and Cohesion-T values. The microstructure of the bulk material produced through the DED process was investigated through scanning electron microscopy (SEM).