Abstract: The production flowsheet for non-quenched and tempered steel F45MnVS is 50 t UHP EAF-LF-VD-260 mm x300 mm and 180 mm x 220 mm billet casting-rolling to Φ20-Φ160 mm products. According to analysis on microstructure of steel, the hot heading crack is caused by block and lamella MnS and attached with Al₂O₃ -MnO-FeO compound oxide. With using the process measures including controlling Al content in steel 0.010%-0.030% , EAF end [C]≥0.20% and end [P]≤0.025% ,[Mn]/[S]＞20, LF refining slag basicity ≥3.0, after VD soft argon blowing for ≥ 12 min, ensuring homogeneous distribution of sulfur in steel, superheating extent of liquid in tundish 20-30 °C, controlling casting speed to prevent MnS segregation, and controlling finishing rolling temperature 850-1000 °C and cooling rate after rolling 2-4℃/s, the main inclusions in steel is long lath MnS, the hot heading test is all qualified without crack and other defects.

Key words: Non-Quenched and Tempered Steel F45MnVS, Hot Heading, Crack, Improvement of Process

摘要： 非调质钢F45MnVS的生产流程为50 t UHP EAF-LF-VD-260 mm×300 mm,180 mm×220 mm坯连铸-Φ20~Φ160 mm材轧制。根据显微组织分析,热顶锻裂纹由块状和片状MnS和附着的Al₂O₃-MnO-FeO复合氧化物引起,通过控制钢中Al 0.010%~0.030%,电弧炉终点[C]≥0.20%,终点[P]≤0.025%,[Mn]/[S]＞20,LF精炼渣碱度≥3.0,VD后软吹氩时间≥12 min,保证钢中硫分布均匀;中间包钢水过热度20~30℃,控制连铸拉速防止MnS偏析;控制终轧温度850~1000℃,轧后冷速2~4℃/s等工艺措施,使钢中夹杂物主要为长条状MnS,热顶锻试验无裂纹和其他缺陷,全部合格。

关键词: 非调质钢F45MnVS, 热顶锻, 裂纹, 工艺改进