昆钢70高碳钢炼钢工艺优化及铸坯质量分析

Research of billet quality and optimization of steel-making process for 70 high-carbon steel in KISC

为改善产品质量,武钢集团昆明钢铁股份有限公司对70钢炼钢工艺进行了优化改进,对铸坯取样进行了低倍组织、中心碳偏析检验分析,对夹杂物进行了大样电解、扫描电镜及能谱检验分析。结果表明:工艺优化后,70高碳硬线钢铸坯质量显著改善,低倍组织大部份缺陷级别不大于0.5级,铸坯中心等轴晶面积比率大于40%;铸坯中心碳偏析指数由1.06降至1.03,成分偏析减小;10 kg铸坯大样电解夹杂物总量由28.95 mg降至9.78 mg,夹杂物以低熔点的锰铝榴石、硅铝酸钙塑性夹杂为主;盘条拉拔断丝率由每百吨7.5次降至4.9次,拉拔性能显著改善。

To improve quality of product the steel making process of 70 high-carbon steel in KISC is optimized and improved and the macrostructure and index of central carbon segregation in the billet are analyzed by sampling. In the meanwhile inclusions in the billet are researched by using large sample electrolysis, scanning electron microscopy and spectroscopy test. The results show that quality of billet is improved significantly after process optimization, defect level of macrostructure for the most 71） high-carbon steel bil- lets is less than 0. 5 grade,ratio of equiaxed zone for the billet is more than 40 % ;index of central carbon segregation in billet is decreased from 1.06 to 1.03 and segregation of chemical compositions is small. The total amount of inclusions in 10 kg large sample e- lectrolysis is reduced from 28.95 mg to 9.78 mg and the inclusions are mainly composed of SiO2-A1203-CaO and SiO2-MnO-A1203 with low melting point and good plastic. The drawing break ratio of wire rod in one hundred tons is decreased from 7. 5 times to 4. 9 times and the drawing performance of wire rod is improved obviously.