R4级海洋系泊链Φ140mm圆钢的开发

Development of Φ140 mm Round Bar for R4 Offshore Mooring Chain

大冶特钢采用60t EBT电弧炉-70t LF精炼＋RH脱气-3流350mm×470mm方坯连铸机-850mm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中140mm R4级系泊链钢。结果表明，通过LF精炼45min，喂Al线和Ca-Si线脱氧后，进行RH≤66．65Pa真空处理20min＋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。

The Ф140 mm bar of steel （0.21C, 1.45Mn, 1.44Cr, 1.21Ni, 0.49Mo, 0.07Nb） forR4 offshore mooring chain was produced at Daye Steel by 60 t EBT arc furnace - 70 t LF refining ＋ RH vacuum degassing - 3 strand 350 mm ×470 mm billet caster - 850 primary mill blooming - 750 semi-continuous mill rolling process. The resuits 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 offshore mooting chain was 14. 8 ×10^ -6, nitrogen content 69.8 ×10^ -6, hydrogen content 1.2 ×10^-6, segregation and porosity rating were 0. 5, inclnsion rating 0 - 1, impact energy at -40 ℃ ≥100 J and each index met the requirement of standard.