含Nb微合金低碳钢奥氏体连续冷却转变行为
Transformation Behavior of Austenite of Nb-bearing Micro-alloyed Low Carbon Steel During Continuous Cooling
王庆敏, 赵海洋, 王立坚, 田士平
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作者单位：秦皇岛首秦金属材料有限公司, 河北 秦皇岛 066326
中文关键字：铌微合金低碳钢； 连续冷却转变曲线； 相变
英文关键字：Nb-bearing micro-alloyed low carbon steel; CCT curve; phase transformation
中文摘要：用MMS-300型热力模拟试验机研究了含铌微合金低碳钢奥氏体连续冷却过程的相变规律，用热膨胀法结合金相法建立了实验钢变形和未变形奥氏体的连续冷却转变曲线(CCT)，研究了加速冷却和热变形对组织转变的影响。结果表明：同静态CCT 曲线相比， 实验钢的动态CCT 曲线整体向左上方移动， 随冷却速度的增大，γ?邛α相变开始温度逐渐降低；高温变形促进铁素体和珠光体相变，同时抑制了贝氏体相变，扩大了铁素体转变区；奥氏体变形对贝氏体转变有双重作用：当冷速较低时，变形抑制贝氏体相变；冷速较高时变形促进贝氏体相变。
英文摘要：The transformation behavior of Nb-bearing micro-alloyed low carbon steel during continuous cooling was investigated by means of MMS-300 thermomechanical simulator. The CCT curves under deformed and un-deformed conditions were obtained by thermal dilation and metallography. The effects of hot deformation and accelerated cooling on microstructure transformation were studied. The experimental results show that the dynamic CCT diagrams shift to the left and upper compared with the static ones, and the onset temperature of γ?邛α transformation is gradually lower with the increase of cooling rate. The transformation of ferrite and pearlite is accelerated and the transformation of bainite is retarded by high temperature deformation，so the transformation range of ferrite increases; the deformation of austenite has double effects on the transformation of bainite: the deformation inhibits bainite transformation at low cooling rate and promotes bainite transformation at high cooling rate.