顶底复吹转炉冶炼双相不锈钢的试验研究

Experimental study on smelting duplex stainless steel in top bottom combined blowing converter

通过500 kg多功能顶底复吹转炉吹炼铁水,进行双相不锈钢冶炼试验。采取钢水脱磷、降碳保铬、钢水深脱硫以及钢水增氮的方法,得到在碳质量分数降到2.0%时,钢水温度控制在1360~1440℃,炉渣的碱度控制在1.4~1.8,炉渣中FeO质量分数控制在15%~20%,钢水中的磷质量分数可以脱除75%以上;在钢水降碳保铬过程中,钢水温度始终控制在1660℃以上,同时随着碳含量降低,逐渐降低氧气比例,增加氩气比例,减少铬元素的氧化;合金化后继续对炉渣进行还原,碱度控制在2.0左右,钢水温度控制在1550~1600℃,渣中的FeO和MnO质量分数之和控制在1%以下,钢水中的硫质量分数可以由0.0040%降低到0.0010%;顶底复吹转炉冶炼双相不锈钢奥氏体和铁素体的占比在49%~51%,钢板的冲击性能远高于标准值180 J,性能满足用户的要求。

A duplex stainless steel smelting experiment was conducted by blowing molten iron in a 500 kg multifunctional top bottom combined blowing converter.By adopting methods such as dephosphorization of molten steel,carbon reduction and chromium retention,deep desulfurization of molten steel,and nitrogen increasing of molten steel,it is obtained that when the carbon mass fraction is reduced to 2.0%,the temperature of molten steel is controlled at 1360-1440℃,the basicity of slag is controlled at 1.4-1.8,w(FeO)in slag is controlled at 15%-20%,and the phosphorus mass fraction in molten steel can be removed by more than 75%.During the carbon reduction and chromium retention process of molten steel,the temperature of the steel is always controlled above 1660℃.At the same time,as the carbon content decreases,the proportion of oxygen gradually decreases,the proportion of argon increases,the oxidation of chromium elements reduces.After alloying,the slag continues to be reduced,with the basicity around 2.0 and steel temperature between 1550 and 1600℃and the sum of FeO and MnO mass fraction in the slag is controlled below 1%,and the sulfur mass fraction in the steel can be reduced from 0.0040%to 0.0010%.The proportion of austenite and ferrite in the smelting of duplex stainless steel in the top bottom combined blowing converter ranges from 49%to 51%,and the impact performance of the steel plate is much higher than the standard value of 180 J,which meets the requirements of users.