适用于冷轧薄板类钢种的合理炉外精炼工艺的探讨

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

炉外精炼过程钢液氧含量对脱硫效率影响显著,对冷轧薄板钢种如在LF中进行深度脱硫,由于必须将钢液氧含量降至很低水平,容易造成钢中硅含量超标等问题。采用LF工艺不能很好地解决既能强烈搅拌钢水促进夹杂物去除又能防止钢水被炉渣和炉气氧化的矛盾,因此须对炉渣进行还原改质处理,同时会导致生产成本增加和转炉连铸机生产节奏变慢等问题。采用CAS和RH精炼工艺能够在防止钢水被炉渣和炉气氧化的前提下,强烈地搅拌钢水以促进夹杂物上浮,生产节奏也能适应大型转炉炼钢和快速板坯连铸需要。对于LCAK、ELC、ULC等冷轧薄板钢种,应以采用CAS和RH精炼工艺方法为主导。

ω（[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, ω（[O]） has to be decreased to a very low level, which easily results in w（[Si]） 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 he 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.