Tailoring of Thermophysical Properties of New TRIP/TWIP Steel Alloys to Optimize Gas Atomization

This work is dedicated to the optimization of the inert gas atomization process applied for production of steel powders. One aim is the optimization of melt parameters with the target to reduce the particle size of atomized powder. A second aim is focused on the atomization equipment optimization. In order to study thermophysical properties of steel melts the development of a new research units was accomplished: Maximum Bubble Pressure device for measurement of the surface tension and density of liquid steels and alloys, patented vibrating finger viscometer, dedicated to the investigation of low-viscosity fluids under the conditions of high temperatures and high reactivity of the studied media; density measurement cell based on the Archimedean principle for the precise estimation of steel alloys density. Then, the effect of thermophysical properties on the inert gas atomization of high-alloy steels was studied. The effects of alloying with Mn and Ni were studied as well as microalloying with S, P, Se on the surface tension and viscosity of liquid steels. Surface tension and viscosity modification of the alloys led to considerable reduction of the size of inert gas atomized powders. Alloying with N allowed finding effect on the powder phase structure.