Particle Size Distribution in Hot Gas Atomization of Stainless Steel Melts

The gas atomization process for metal powder production is strongly influenced by the thermodynamic and fluid-dynamic conditions of the atomizing gas. In this study, stainless steel (316L) powders produced using a close-coupled gas atomizer (CCA) with heated nitrogen and argon were investigated. A systematic experimental campaign was conducted by varying gas type, gas pressure, and gas temperature to analyze their impact on the particle size distribution and morphology. Numerical gas-flow simulations were performed to characterize the dependence of the gas velocity field in the atomization region on the applied process parameters. Based on the experimental and numerical results, classical correlations for characteristic particle size prediction have been adapted for CCA hot gas atomization by introducing an additional temperature scaling term (TG/TR)t. The modified correlations improved the prediction accuracy compared with the original formulations. For the Lubanska correlation, the mean prediction error could be significantly reduced. Furthermore, general linear models and a complementary analysis of covariance (ANCOVA) were used to evaluate the associations of gas temperature, gas type, and gas pressure and the derived flow parameters with the particle size distribution. The combined experimental–numerical approach provides further insight into hot gas atomization of metal melts and supports the optimization of process parameters for tailored metal powder production.