Instability of scan tracks of selective laser sintering of high speed steel powder

The tendency for breaking up of scan tracks into balls during the SLS of HSS powders increases with increasing oxygen content in the powder particles. The balling kinetics during SLS of HSS powder particles with a high oxygen content is controlled mainly by the fluid flow resulting from the presence of the surface tension gradient within the melt pool produced by using a high laser energy. Increasing incident laser energy density for the SLS of powder particles with a high oxgyen content can cause an increase of the heat input, temperature gradient and surface tension gradient across the melt pool surface. This leads to increasing fluid flow in the melt pool and tends to enhance the breaking up of a scan track into balls. Materials: M2-94 and M3/2-100.