Abstract: The steel grade 18CrNiMo7-6 with diameter of Φ115 ~250 nun round from process route of hot metal + scrap-120 t BOF-RH- 410 mm x530 mm continuous casting-bloom heating by walking forward heating fumace-750 rolling¬annealing. Its chemical composition is (/% : 0. 15 ~ 0. 19C, 0. 25 ~ 0. 40Si, 0. 40 ~ 0. 60Mn, 1.50 ~ 1. 80Cr, 1.40 ~ 1.70Ni, 0.25 ~0. 35Mo, W0. 020P, W0. 020S,0.020 ~ 0. 040Al, 0.0100 ~ 0.0200N). Through deoxidization and alloy addition during tapping, deep vacuum degassing not less than 15 minutes, soft bubbling with Nitrogen, super heat control in tundish, casting speed of 0. 48 m/min, full process argon protection and applications of F-EMS and M-EMS, annealing after rolling etc. , the final product^'s macro-inclusion not more than 20 mm/dm³, carbon center segregation not more than 1. 10 and grain size finer than 7, which meet the specification requirements.

摘要： 采用铁水+废钢-120 t转炉-LF-RH-410 mm×530 mm大方坯连铸-步进式加热炉-750轧机轧制-退火的流程生产规格Φ115～250 mm 18CrNiMo7-6（/%:0.15～0.19C,0.25～0.40Si,0.40～0.60Mn,1.50～1.80Cr,1.40～1.70Ni,0.25～0.35Mo,≤0.020P,≤0.020S,0.020～0.040Al,0.0100-0.0200N）。通过控制出钢预脱氧和合金化,深真空时间≥15 min,软吹氮气,控制中间包钢水过热度,拉速0.48 m/min,全过程Ar气保护,连铸M-EMS和F-EMS,轧制后退火等工艺措施,生产的产品宏观夹杂物检测含量≤20mm/dm³,碳中心偏析指数≤1.10,晶粒度≥7级,钢材各项指标满足协议要求。

关键词:  410 mm x 530 mm连铸坯, 18CrNiMo7-6钢, 宏观夹杂物, 晶粒度