Killed & Semi-killed Steel

killed steel refers to the removal of all oxygen that could react with carbon once the steel is in plate form or solid form. Semi-killed is where the oxygen is not completely removed in that when cooling to a solid there is CO degassing of the ingot that benefits the ingot by minimizing ingot shrinkage. Rimming is similar to semi-killed steel except that the CO degassing occurs during the enter solidification process of the ingot such that there are not gas bubbles or porosity.