高强焊丝钢N2M2T连铸坯表面缺陷分析及工艺改进

Analysis of Surface Defects of High Strength Welding Wire Steel N2M2T Continuous Casting Billet and Process Improvement

针对某钢厂在冶炼N2M2T高强焊丝钢时,连铸坯表面出现的凹陷、角部深振痕裂纹及渣坑等表面缺陷,结合理论分析及现场实际生产情况,从保护渣理化性能、结晶器振动参数、一冷配水及钢中N含量等对铸坯表面产生的缺陷进行分析。结果表明,连铸坯产生的表面缺陷主要与保护渣理化指标、结晶器振动参数、钢中N含量有关,而与一冷配水关系不大。生产实践表明,通过将保护渣碱度从0.6提高到1.19,w[C]从13.51%降低到8.21%,粘度从0.666 Pa.s降低到0.156 Pa.s,结晶器振动参数偏斜率由0.15提高至0.20,振频公式由60+50 V调整为90+60V,钢中N含量控制在<50×10^(-6),连铸工序△N<7×10^(-6)等措施,N2M2T高强焊丝钢连铸坯的表面缺陷得到明显改善,铸坯合格率从85%提高到95%以上,为后续轧钢的稳定轧制提供了保证。

In response to the surface defects such as concavities,deep vibration marks,cracks,and slag pits on the surface of continuous casting billets during the smelting of N2M2T high-strength welding wire steel in a certain steel plant,combined with theoretical analysis and actual production conditions on site,an analysis was proposed to analyze the surface defects of N2M2T high-strength welding wire steel continuous casting billets from four aspects:the physical and chemical properties of protective slag,mold vibration parameter mode,primary cooling water distribution,and N content in the steel.The analysis results indicate that the surface defects generated by continuous casting billets are mainly related to the physicochemical indicators of the protective slag,mold vibration parameters,and N content in the steel,but not to the primary cooling water distribution.Production practice shows that by increasing the alkalinity of the protective slag from 0.6 to 1.19,the C content is reduced from 13.51%to 8.21%,and the viscosity is reduced from 0.666 Pa.s to 0.156 Pa.s;The deviation rate of mold vibration parameters has been increased from 0.15 to 0.20,and the vibration frequency formula has been adjusted from 60+50 V to 90+60 V;Control the N content in steel to<50×10^(-6),continuous casting process△N<7×10^(-6);The surface defects of N2M2T high-strength welding wire steel continuous casting billet have been significantly improved,and the qualification rate of the billet has increased from 85%to over 95%,providing assurance for stable rolling of subsequent steel rolling.