Analysis of the influence of the gas velocity, particle size and nucleation temperature on the thermal history and microstructure development in the tool steel during atomization

Applying developed mathematical model of cooling and solidification of a single spherical droplet in atomization process, the influence of nitrogen gas velocity and other parameters as nucleation temperature on the thermal history of a droplet with various diameters during atomization is studied. Based on the comparison of results of mathematical modeling and microstructural observations, the thermophysical conditions for the transition from dendritic to cellular (grain-refined) microstructure development in the rapidly solidified powder particles from the Ch12MF4 steel are predicted.