合金工具钢S2盘条的开发

Development of Coil of Alloy Tool Steel S2

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(/%:0.63~0.69C,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),并进行120 t 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1 620~1 660℃,BOF出钢采用Si-Mn预脱氧,LF精炼渣(/%:8~10 MgO,44~45 CaO,5~10 SiO_2,25~35 Al_2O_3),LF精炼结束喂钙线,连铸钢水过热度≤25℃,拉速0.65 m/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,Φ8 mm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。

By testing with a 80 kg 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 120 t BOF-LF-VD-300 mm × 390 mm 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%v, control of BOF end [ C] 0. 10% -0. 30%, end [ P] ≤〈0. 012% , liquid end temperature 1 620 - 1 660 ℃, using Si-Mn pre-deoxidation in BOF tapping, LF refining slag （/% ： 8 - 10MgO, 44 -45CaO, 5 - 10SiO2, 25 N35Al2O3 ） , feeding calcium wire at end of LF refining, overheating extent of casting liquid ≤ 25 ℃, casting speed 0. 65 m/min, and controlling cooling after rolling, the coil of alloy tool steel S2 is successfully developed. Examination results show that the each property index of q58 mm hot-rolled coil meets the re- quirement 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.