Abstract: The φ140 mm of steel(0.21C,1.45Mn,1.44Cr,1.21Ni,0.49Mo,0.07Nb)for R4 of fshore mooring chain was produced at Daye  Steel by 60 t EBT are fumnace -70 t LF refining + RH vacuum degassing -3 strand 350mm×470 mm billet caster -850 primary mill blooming -750 semi-continuous mill rolling process. The re-  sults showed that with LF refining for 45 min,feeding Al wire and Ca-Si wire deoxidizing,then ≤66.65 Pa RH vacuum degassing for 20min + soft argon blowing for ≥10 min,the oxygen content in finished products of steel for off shore mooring chain was 14.8×10-6,nitrogen content 69.8×10^-6,hydrogen content 1.2×10^-6,segregation porosity rating were 0.5,inclnsion rating 0～1, impact energy at -40 ℃≥100 and each index met the require ment of standard.

摘要： 大冶特钢采用60tEBT 电弧炉-70 tLF 精炼+RH 脱气-3流350mm×470 mm方坯连铸机-850 mm 初轧+750mm 半连轧工艺生产了成分(%)为0.21C、1.45Mn、1.44Cr、1.21Ni、0.49Mo、0.07Nb φ140 mm R4 级系泊链钢。结果表明，通过LF 精炼45 min,喂Al线和Ca-Si线脱氧后，进行RH≤66.65 Pa真空处理20 min+ 软吹氩≥10min,使系泊链钢成品中的氧含量达14.8×10^-6,氮含量69.8×10^-6,氢含量1.2×10^-6,偏 析和疏松0.5级，夹杂物0~1级， -40℃时冲击功≥100J,各类指标均满足标准要求。