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利用DIL 805A淬火变形膨胀仪测定了提速列车用Nb-V复合微合金化弹簧钢60Si2CrVAT过冷奥氏体的连续冷却转变曲线,并结合金相-硬度法探讨了不同冷速下实验钢组织的变化,分析了Nb含量对60Si2CrVAT过冷奥氏体的连续冷却转变的影响.结果表明:Nb含量的增加,促进了高温、中温转变,且珠光体转变区间随之变宽,马氏体转变点由284.2℃降低到258.3℃;铁素体消失的冷速由0.3℃.s-1提高到0.5℃.s-1,珠光体消失的冷速由2℃.s-1提高到3℃.s-1,贝氏体消失的冷速也相应地由3℃.s-1提高到5℃.s-1,贝氏体开始出现的冷速由0.4℃.s-1提高到0.6℃.s-1,马氏体出现的冷速同为1℃.s-1.
The continuous cooling transformation curve of 60Si2CrVAT supercooled austenite in Nb-V composite microalloyed spring steel for speed-raised train was measured by DIL 805A quenching deformation dilatometer. The microstructure and hardness of experimental steel The effect of Nb content on the continuous cooling transformation of 60Si2CrVAT supercooled austenite was analyzed.The results show that the increase of Nb content promotes the transformation of high temperature and medium temperature and the broadening of pearlite transformation range and the change of martensite transformation point From 284.2 ℃ to 258.3 ℃; the cooling rate of ferrite disappearing increased from 0.3 ℃ .s-1 to 0.5 ℃ .s-1, the cooling rate of pearlite disappeared from 2 ℃ .s-1 to 3 ℃ .s -1, and the cooling rate of bainite disappeared from 3 ℃ .s-1 to 5 ℃ .s-1, the initial cooling rate of bainite increased from 0.4 ℃ .s-1 to 0.6 ℃ .s -1, martensite appeared with the same cooling rate 1s .s-1.