Abstract: By testing with a 80kg vacuum induction furnace and measuring continuous cooling transformation (CCT) curves by using Gleeble 3800 hot simulation machine the chemical composition of steel S2 (/%: 0.63~0.69C, 1.00~1.20Si, 0.40~0.60Mn, 0.20~0.40Cr, 0.40~0.50Mo, 0.15~0.25V, 0.10~0.30Ni, 0.010~0.030Nb, ≤0.015P, ≤0.010S) has been designed, and the commercial production by 120t BOF-LF-VD-300mmx390mm bloom casting-breakdown-high speed wire rolling-Stelmor control cooling process has been carried out. With the process measures including hot metal dephosphorization, sulphur content in metal ≤0.010% , control of BOF end[C] 0.10% ~0.30% , end[P] ≤0.012% , liquid end temperature 1620~1660℃, using Si-Mn pre-deoxidation in BOF tapping, LF refining slag (/%: 8~10MgO, 44~45CaO, 5~10SiO₂,25~35Al₂O₃,feeding calcium wire at end of LF refining, overheating extent of casting liquid ≤25℃，casting speed 0.65m/min, and controlling cooling after rolling, the cqil of alloy tool steel S2 is successfully developed. Examination results show that the each property index of Φ8mm hot-rolled coil meets the requirement of technical specification, including the austenite grain size rating 8.5~9.0, the depth of decarburization layer≤0.5%D, the HRC hardness value of hot-rolled coil 50 and the variation of HRC hardness value of same coil less than 6.

摘要： 通过80 kg真空感应炉试验及Gleeble 3800热模拟试验机测试了连续冷却相转变（CCT）曲线,设计了S2钢的化学成分（/%:0.630.69C,1.001.20Si,0.400.60Mn,0.200.40Cr,0.400.50Mo,0.150.25V,0.100.30Ni,0.0100.030Nb,≤0.015P,≤0.010S）,并进行120t BOF-LF-VD-300 mm×390 mm方坯连铸-开坯-高线轧制-斯太尔摩控冷流程的工业性生产。通过铁水脱硫,铁水硫含量≤0.010%,BOF终点[C]0.10%0.30%,[P]≤0.012%,钢水终点温度1620~1660℃,BOF出钢采用Si-Mn预脱氧,LF精炼渣（/%:8~10MgO,44~45CaO,5~10SiO₂,25~35Al₂O₃,LF精炼结束喂钙线,连铸钢水过热度≤25℃,拉速0.65m/min和轧制控冷等工艺措施,成功开发了合金工具钢S2盘条。检验结果表明,Φ8mm热轧盘条奥氏体晶粒度为8.5~9.0级,脱碳层厚度≤0.5%D,热轧盘条HRC硬度值50,同卷HRC硬度值波动小于6,各项性能满足技术要求。