100t LF Si-Ca脱氧低铝锅炉管用钢 15CrMoG 夹杂物分析

高压锅炉管用钢15CrMoG（/%:0.12~0.18C,0.17~0.35Si,0.40~0.70Mn,≤0.015P,≤0.015S,0.80~1.10Cr,0.40~0.55Mo,≤0.020Alt）的生产工艺流程为60%铁水+优质废钢-100t UHP EAF-LF-VD-Φ500mm坯连铸-轧制。通过电弧炉出钢Al-Si预脱氧,LF精炼Si-Ca脱氧,优化精炼渣系的组成为（/%）:55~60CaO,30~35Al₂O₃,5~10SiO₂,（CaO）/（Al₂O₃）=1.41~1.74,精炼后钢水中的Alt为0.011%~0.014%。Φ140mm和Φ160mm热轧材的夹杂物分析结果表明,钢中夹杂物中MnS为10%,铝酸钙为75%,SiO₂ 7.5%,含Ti氧化物5%,其它2.5%,钢中≤5.0μm夹杂物占95%以上,满足锅炉管用钢15CrMoG的技术要求。

Analysis on Inclusions in Low Aluminium Steel 15CrMoG for Boiler Pipe Refining in 100t LF by Si-Ca Deoxidation

The production process flowsheet of steel 15CrMoG for high pressure boiler pipe (/% : 0.12~0.18C, 0.17~0.35Si, 0.40~0.70Mn, ≤0.015P, ≤0.015S, 0.80~1.lOCr, 0.40~0.55Mo, ≤0.020Alt) is 60% hot metal + quality scrap- 100t UHP EAF-LF -VD-Φ500mm bloom casting-rolling. With Al-Si pre-deoxidation in EAF tapping, Si-Ca deoxidation in LF refining, and using optimized refining slag (/% ) : 55~60CaO, 30~35A1₂O₃,5~10SiO₂, (CaO)/( A1₂O₃) =1.41~1.74, the Alt content in refined liquid is 0.011%~0.014%. The analysis results on inclusions in Φ140mm and Φ160mm hot rolled products show that the ingredient of inclusions in steel is 10% MnS, 75% calcium aluminate, 7.5% SiO₂, 5% oxide containing Ti, and 2.5% others, and the ≤5.0μm inclusions make up more than 95% of the total mount of inclusions in steel to meet the technical requirement of steel 15CrMoG for boiler pipe.