Discussion on Proper Secondary Refining Methods of Steel Grades for Cold Rolled Sheets

Abstract

w([O]) in liquid steel largely influences the desulphurization rate during ladle refining.To make high desulphurization rate of steels in ladle furnace refining for cold rolled sheets,w([O]) has to be decreased to a very low level,which easily results in w() out off the specification range of the steels.If LF refining is applied to the steels for cold rolled sheets,the contradiction between stirring the liquid steel to accelerate removing of non-metallic inclusions and preventing reoxidation of the steel by oxidizing slag and the atmosphere is occurred.Hence,high reducing slag should be made,which increases the production cost and slows down the production paces of BOF and continuous casting owing to the increase of the LF refining time.Different from LF,using CAS and RH refining methods,the liquid steels can be strongly stirred while the reoxidation of the steels by the oxidizing slags and atmosphere can be prevented.Also,the production paces of CAS and RH are quicker and easier to match with the paces of BOF and slab continuous casting.So,CAS and RH should be chosen as the main refining method for producing steels for cold rolled sheets.