奥氏体状态对 Mn-Cr 齿轮钢连续冷却相变组织的影响

使用Cleeblel500热模拟试验机研究了成分(%)为：0.23C,0.74Mn,0.90Cr 齿轮钢奥氏体晶粒尺 寸和变形(真应变量0.4)对连续冷却相变组织的影响和连续转变冷却(CCT)曲线。实验结果表明，当齿轮钢 未变形时，获得完全多边形铁素体+珠光体混合组织的临界冷速为0.5~1℃/s,冷速较快时，中温相变产物 由贝氏体及针状铁素体组成；奥氏体变形时，多边形铁素体相变开始温度升高，获得完全多边形铁素体+珠光 体混合组织冷速增大，为1~2℃/s,中温相变产物没有出现贝氏体，只有针状铁素体。

Effect of Austenitic State on Continuous Cooling Transformation Structure of Mn-Cr Gear Steel

The effect of austenite grain size and deformation(true strain 0.4) of gear steel 0.23C-0.74Mn-0.90Cr on  continuous cooling transformation(CCT) structure and CCT curves have been studied by Gleeble 1500 hot simulator. Test results showed that as gear steel without deforming, the critical cooling rate to get complete polygonal ferrite + pearlite structure was 0.5～1 ℃/s, as cooling rate quicker, the products of medium temperature transformation consisted of bainite and acicular ferrite; as austenite deforming the polygonal ferrite initial transformation temperature went up, the cooling rate to get complete polygonal ferrite + pearlite structure up increased to 1～2 ℃/s, and the medium temperature transformation product was only acicular ferrite without bainite observed.