不同钢种炉外精炼钙处理工艺的选择

Selection of calcium treatment technology of LF refining for different steel

为了优化不同钢种的LF精炼钙处理工艺,研究了高强结构钢、低碳结构钢、焊瓶钢、耐磨钢、高碳钢在LF精炼及钙处理过程中夹杂物的演变机理。结果表明,渣-钢反应时间越长,钙处理前的夹杂物变性越彻底。钙处理前焊瓶钢夹杂物以Al2O3为主,高强结构钢、低碳结构钢夹杂物以MgO-Al2O3-CaO复合夹杂为主;高碳钢、耐磨钢夹杂物以低熔点的Al2O3-CaO夹杂为主。钙处理工艺会增加钢液中夹杂物数量及尺寸。控制Al2O3-SiO2-MnO复合夹杂物的关键是避免LF精炼中后期进行硅锰合金化。综合考虑各方面因素,建议焊瓶钢增加当前的钙线喂入量,高强结构钢、低碳结构钢使用轻钙处理工艺,高碳钢、耐磨钢取消钙处理工艺。

In order to optimize LF refining calcium treatment process for different steels,the evolution mechanism of inclusions in high strength structural steel,low carbon structural steel,welded cylinder steel,wear resistant steel and high carbon steel during LF refining and calcium treatment was investigated.The results show that the longer the slag-steel reaction time,the more thorough the inclusion modified before calcium treatment.Before calcium treatment,Al2O3 is the main inclusion of welded cylinder steel,MgO-Al2O3-CaO composite is the main inclusion of high strength structural steel and low carbon structural steel,and Al2O3-CaO inclusion with low melting point is the main inclusion of high carbon steel and wear-resistant steel.The amount and the size of inclusions in molten steel can be increased in the process of calcium treatment.The key to control Al2O3-SiO2-MnO composite inclusions is to avoid Si-Mn alloying in the middle and late stages of LF refining.Considering all factors,it is suggested that the current amount of feeding calcium wire should be increased for welded cylinder steel,light calcium treatment process should be used for high strength structural steel and low carbon structural steel,and calcium treatment process should be cancelled for high carbon steel and wear resistant steel.