电弧炉短流程冶炼石油套管钢中夹杂物的演变规律

为研究石油套管钢(34Mn6)中夹杂物的演变规律,对钙处理效果进行精准化控制,进行全流程取样分析,通过采用SEM-EDS分析夹杂物形貌和成分,同时结合Aspex夹杂物自动分析仪统计夹杂物的数量、成分和尺寸分布。研究结果表明,LF精炼具有较好的脱硫与脱氧能力;钙处理前,由于渣钢反应的进行,夹杂物数量明显减少,夹杂物成分中SiO₂含量增加;经过钙处理后,夹杂物成分发生显著变化,由MgO-Al₂O₃系转变为MgO-Al₂O₃-CaO系和SiO₂-Al₂O₃-CaO系,夹杂物形貌由尖角夹杂向球状夹杂过渡。在铸坯中,夹杂物数量减少,其成分已偏离液相区,向富CaO区域移动。对钙处理进行优化,通过利用热力学软件FactSage进行计算,得出钢液中钙的质量分数稳定在0.001 3%时对夹杂物的改性效果最佳,钢液中的夹杂物控制较好。

Evolution law of inclusions in petroleum casing steel during short process smelting by EAF

In order to study the evolution law of inclusions in petroleum casing steel (34Mn6) and precise control of calcium treatment effect, sampling and analysis of the whole process were carried out. The morphology and composition of inclusions were analyzed by SEM-EDS, and the number, composition and size distribution of inclusions were counted with the Aspex automatic inclusion analyzer. The research results show that LF refining has good desulfurization and deoxidation ability. Before calcium treatment, the number of inclusions decrease significantly due to the progress of slag-steel reaction, and the content of SiO₂ in the inclusions increases. After calcium treatment, the composition of inclusions change significantly, which transformed from MgO-Al₂O₃ system into MgO-Al₂O₃-CaO system and SiO₂-Al₂O₃-CaO system, and the inclusion morphology transitions from sharp-angle inclusions to spherical inclusions. In the cast billet, the number of inclusions decreases, and its composition has deviated from the liquid phase region and moved to the CaO rich region. Calcium treatment was optimized and calculated by thermodynamic software FactSage. It is concluded that when the Ca mass fraction in molten steel is stable at 0.001 3%, the modification effect of inclusions is the best, and inclusions in molten steel are well controlled.