Titanium alloy powder preparation for selective laser sintering

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Abstract
Selective laser sintering (SLS) is a solid freeform fabrication process whereby a part is built layerwise by scanning a powder bed. The processability of metal powder varies depending on the state of the powder prior to SLS. A powder thermal pre‐treatment was developed which involved degassing the powder at an elevated temperature in a vacuum. Without powder thermal pre‐treatment, the powder may flow poorly and may “ball” or form molten clumps during the laser exposure rather than wetting into the present and previous layer. These effects result in SLS parts with poor surface finish, mechanical properties and density. The purpose of this study was to identify for titanium alloy powder the mechanisms responsible for the improvements obtained after powder thermal pre‐treatment and to optimize the thermal excursion.