奥氏体变形条件下低碳微合金钢中的贝氏体相变

采用Gleeble-1500热模拟机对低碳Mn-Nh-Ti钢进行了奥氏体区变形和变形后的冷却试验，借助于光学显微镜和扫描电镜分析了变形和冷却速度对显微组织的影响。结果表明，随着奥氏体形变量的增大，奥氏体向铁素体的相变增加，向贝氏体的相变减少，贝氏体中的铁素体和小岛由细长条状逐渐向近等轴状变化，铁素体板条间的小岛逐渐变化为存在于某些铁素体的晶界上。随着变形后的奥氏体冷却速度增大，铁素体量减少，贝氏体量增加，粒状贝氏体也逐渐由板条贝氏体所取代。

Bainite Transformation of Ausformed Low Carbon Microalloyed Steel

Using Gleeble1500 thermomechanical simulator,the experiments of ausforming treatment and the subsequent cooling were carried out for low carbon Mn-Nb-Ti steel.The influence of deformation and cooling rate on the microstructure of the steel was analyzed by means of optical microscope and SEM.The results show that ferrite fraction increases and bainite fraction decreases,ferrite and its islet in bainite change gradually from slight band shape into nearly equiaxed shape,the islets located among ferrite lathing evolve gradually into some ferrite grain boundary with increasing the strain amount of austenite,ferrite fraction decreases,bainite fraction increases,and the granular bainite is replaced gradually by lath bainite with increasing the cooling rate after ausforming.