【摘要】 利用Gleeble-1500热模拟试验机对低碳合金钢进行了不同变形量、冷却速度的热模拟实验。经OM和TEM观察表明,当未变形奥氏体以10~30℃/s连续冷却时,贝氏体铁素体优先在奥氏体晶界处形核,然后呈板条状从奥氏体晶界向晶内长大,并且可以从最终的组织看到原奥氏体晶界。与未变形奥氏体相比,当奥氏体在880℃经过40%变形、并以10~30℃/s连续冷却时,由于变形增加了奥氏体晶粒的形变储存能,促进了先共析铁素体在奥氏体晶界位置优先形成,所以贝氏体铁素体只能在奥氏体晶内形成,从最终的室温组织不能看到原奥氏体晶界。更多还原

【Abstract】 The thermal simulation experiments with different deformation amounts and cooling rates of low carbon Nb-microalloyed steel were performed using Gleeble 1500 thermomechanical simulator.The observations by OM and TEM reveal that when undeformed austenite continuously cooled at 10 to 30℃/s,bainitic ferrite nucleated mainly at austenite grain boundaries,grown up like parallel lath into the bulk from the grain boundaries of austenite,and original austenite grain boundaries could be seen.Compared with the undeformed austenite,when austenite deformed by 40% at 880℃ and continuously cooled at 10 to 30℃/s,the austenite grain boundaries were occupied by polygonal ferrite because deformation can increase the deformation energy of austenite grain.Therefore,bainitic ferrite only nucleated in the grain of austenite,and original austenite grain boundaries can not be seen.更多还原