薄带连铸低碳钢过冷奥氏体组织转变的原位观察

摘要

利用共聚焦激光扫描显微镜对薄带连铸低碳钢过冷奥氏体的组织转变进行了原位观察。结果表明：薄带连铸低碳钢原始奥氏体晶粒粗大，平均粒径约200μm，室温组织主要由贝氏体和多边形铁素体组成；在过冷奥氏体组织转变过程中，BF板条主要形核位置为原奥氏体晶界上、奥氏体晶内夹杂处、晶界多边形铁素体或已生长的BF板条上，并且后形核生长的BF板条不会穿过先形核生长的BF板条，前后形核生长的BF板条有一定的取向角度；BF板条的生长速率受温度、形核位置和生长取向的影响。%In-situ observation for super-cooled austenite microstructure transformation of the strip casting low carbon steel was performed by confocal laser scanning microscopy. The results show that the average grains size of original austenite grains in strip casting low carbon steel was about 200 μm, the room temperature microstructure was mainly composed of bainite and polygon ferrite. The main nucleation positions of bainitic ferrite plats （BF） were original austenite grain boundary, inclusions in austenite transgranular and grain boundary polygon ferrite or grown BF plats during super-cooled autensite microstructure transformation, the first nucleation BF plate did not across the secondary nucleation BF plate, and the former and the latter took a certain orientation angle. The temperature, nucleation position and growth orientation had effects on the growth Speed Of BF plate.