Ladle Metallurgy Apr23

Ladle Metallurgy

Ladle Metallurgy After tapping of steel from a primary steelmaking furnace such as BOF, EAF or EOF, molten steel for high quality or specialty applications is subjected to further refining in a number of alternative processes collectively known as ladle metallurgy. Ladle metallurgy is sometimes also called ladle refining or secondary steelmaking. Ladle metallurgy processes are commonly performed in ladles. Tight control of ladle metallurgy is associated with producing high grades of steel in which the tolerances in chemistry and consistency are narrow. The objectives of ladle metallurgy are the following. Homogenization – Homogenization of chemical composition and temperature of liquid steel in the ladle Deoxidization or killing – Removal of oxygen Superheat adjustment – Heating of the liquid steel to a temperature suitable for continuous casting Ferro alloys and carbon additions – Making adjustments in the chemistry of liquid steel. Vacuum degassing – Removal of hydrogen and nitrogen Decarburization – Removal of carbon for meeting the requirement of certain grades of steel. Desulfurization – Reduction of sulfur concentrations as low as 0.002% Micro cleanliness – Removal of undesirable nonmetallic elements Inclusion morphology – Changing the composition of remaining impurities to improve the microstructure of the steel Mechanical properties – Improvement in toughness, ductility, and transverse properties Depending on the types of steel required, one or more of the following ladle metallurgy processes are used. These are (i) rinsing or stirring, (ii) ladle furnace, (iii) ladle injection (iv) ladle refining, (v) degassing processes, (vi) AOD process, and (vii) CAS-OB (Composition adjustment by sealed argon bubbling with oxygen blowing) process. Some of the ladle metallurgy processes are shown in Fig 1. Fig 1 Some of the ladle metallurgy processes  Historical background  The treatment of steel in the ladle started around 45 years ago when the first ladle-to-ladle and ladle-to-ingot mold vacuum...