高碳铭GCrl5轴承钢中镁铝夹杂物形成与控制工艺实践

GCr15钢的生产流程为120 t BOF-LF-RH-CC工艺。BOF出钢加200 kg铝块进行强脱氧,同时LF过程控制Al含量至0.030%～0.045%,LF结束夹杂物主要为MgO·Al₂O₃,RH真空后MgO·Al₂O₃夹杂物被去除,钢水中夹杂物以钙铝酸盐为主,但是连铸浇铸过程MgO·Al₂O₃夹杂物又会重新生成。因为LF精炼过程Al-MgO和C-MgO反应的存在,高碳铝脱氧GCr15轴承钢LF精炼结束更容易获得MgO·Al₂O₃夹杂物,并促进中间包钢水MgO·Al₂O₃夹杂物重新生成。当BOF出钢仅加40 kg铝块进行预脱氧,LF结束钢水MgO·Al₂O₃夹杂物数量显著降低,同时中间包钢水中MgO·Al₂O₃夹杂物不再重新生成。此外,将低钛低铝硅铁由出钢过程改为LF过程加入,也可以有效控制钢水中MgO·Al₂O₃夹杂物数量。 

Formation of Magnesium-Aluminum Inclusion in High Carbon Chromium GCrl5 Bearing Steel and Control Process Practice

The GCrl5 steel production flow steel is 120 t BOF-LF-RH-CC process. As adding 200 kg aluminum block at BOF tapping for strong deoxidation and controlling the aluminum content 0.030% ~ 0.045% in steel in LF process, at end LF the main inclusions in steel are MgO ·Al₂O₃ and the MgO , Al₂O₃ inclusions are removed during RH degassing and the calcium aluminate inclusions are main inclusions in steel after RH. However, but MgO·Al₂O₃inclusions are formed again in the tundish steel. Due to the existence of Al-MgO and C-MgO reactions in LF refining process, the MgO ·Al₂O₃ inclusions could be formed again after LF refining in high carbon aluminum deoxdized GCrl5 bearing steel. However, when just adding 40 kg aluminum block for preliminary deoxidation in the BOF tapping process, the amount of MgO·Al₂O₃ inclusions in steel significantly decrease after LF refining, and the regeneration of MgO  Al₂O₃ inclusions in tundish steel could be prevented. In addition, adding low titanium and low aluminum ferrosilicon in the LF refining process instead of adding in tapping process effectively control the amount of MgO · Al₂O₃ inclusions in steel.