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

In this experiment water/gas atomized M3/2 and M2 HSS powders were laser sintered by scanning a single track on the powder bed at various laser powders and scan rates. The purpose is to establish an understanding of laser sinterability of these powders and to determine a window of optimum processing conditions to avoid the balling phenomenon. The laser used in this experiment is a 600 W, CW, Carbon dioxide laser with a beam size of 0.5 mm. The loosely packed HSS powders were placed in a mild steel tray inside a container protected by an argon atmosphere and they were levelled with blade so as to obtain a flat powder surface. The surface of the as-sintered samples were examined using JEOL 5410 and 6300 scanning electron microscopy.