An experimental study of number concentration gradients of inclusions during deoxidation using inductive and gas stirring

Concentration gradients of inclusions during inductive and gas stirring of AISI H13 tool steel in a ladle have been studied using a unique experimental technique at Uddeholm Tooling AB in Sweden. A specially designed sampling equipment, which allows five samples to be taken at the same time and at different depths was used. The aim was to experimentally quantify the existence of inclusion size population gradients in different positions of the steel melt. One experiment was carried out using induction stirring and one using gas stirring. The main findings from the induction stirring experiment was that i) concentration gradients of inclusions exist, ii) the number of inclusions decreases with stirring time in all positions, and iii) that the superficial positions show a more rapid decrease than the deeper ones. The main findings from the gas stirring experiment are that i) concentration gradients of inclusions exist, ii) the superficial positions are mostly affected by the gas plumes, and show a very pronounced decrease of the number of inclusions with stirring time, and iii) the deeper positions and also one of the superficial position (no "3") shows no decreasing trend.