Influence of powder deposition and exposure strategy on the process window of water-atomized stainless steel 1.4404 in PBF-LB/M

This study compares the processability of water-atomized (WA) and gas-atomised (GA) 1.4404 stainless steel powder in powder bed fusion of metals using a laser beam (PBF-LB/M). Powder spreading was analysed as a function of layer thickness and recoater speed and correlated with part density using single and double exposure strategies. WA powder exhibits reduced flowability and higher powder bed roughness, leading to a narrower process window and increased sensitivity to layer thickness and recoater speed. Nevertheless, relative densities above 99.9% are achievable through targeted adjustment of spreading and exposure parameters. Double exposure mitigates lack-of-fusion defects and extends the stable parameter range. WA powder increases process sensitivity without preventing the achievement of maximum density.