Effect of Surface Tension on Gas Atomization of a CrMnNi Steel Alloy

The aim of the current research is the experimental investigation of the mass median particle size d(50) as a function of surface tension for liquid Cr-Mn-Ni steel alloy with 16% Cr, 7% Mn, and 9% Ni. To modify the liquid steel design sulfur was add to the Cr-Mn-Ni steel in five steps up to a 1000mass ppm. The surface tension of the liquid steel alloy was measured using maximum bubble pressure method and yttria stabilized capillary in a temperature range from 1701 to 1881K. In addition, the same steel charges were sprayed to steel powder using a vacuum inert gas atomization using pure argon gas. The increase of sulfur in Cr-Mn-Ni steel will decrease the surface tension to 0.91Nm(-1). The temperature coefficient of surface tension is positive for all investigated Cr-Mn-Ni alloys due to a sulfur content 100mass ppm. The final mass median particle size d(50) decreases from 54.3 mu m for AISI 304 reference steel alloy to 17.1 mu m for Cr-Mn-Ni steel alloy (16-7-9 S10) with the highest sulfur content and the lowest surface tension of all investigated liquid steels. It is concluded from the present work that surface tension is the decisive factor in adjusting d(50) at a constant spraying parameters.