Effects of the powder morphology, size distribution, and characteristics on the single track formation in selective laser melting of H13 steel

Abstract

This study focuses on the formation of a single-line track in selective laser melting (SLM), based on the powder morphology, size distribution, and characteristics. A chromium-molybdenum-vanadium steel, AISI H13, was used as a metal powder. The relationship between the powder morphology, size distribution, and the powder-bed layer characteristics, such as the thermal conductivity and laser absorption under a N₂ or Ar atmosphere, was determined. Subsequently, its effect on the built width, height, and contact angle was investigated by observing the cross-sectional profile of the structure. Finally, the powder morphology, size distribution, and characteristics were linked to the processability in SLM and were found to be closely related to the powder-bed layer characteristics, which affects the first deposition layer of the SLM H13 steel. The effect of the atmosphere on the contact angle is notable. The use of the Ar atmosphere to fabricate the continuous and stable structure at the minimum volume specific energy density (VSED) is reasonable because of its thermal property. The powder morphology, which depends on the atomization method, yields a variation in the bulk density and thermal property of the powder bed layer. The powder bed layer with the irregular powder can be influenced by the atmospheric characteristics because of its low bulk density. The effect of the powder-size distribution on the contact angle depends on the powder morphology. The spherical powder can perform the low-contact angle for a lower VSED.