【摘要】 用扫描电子显微镜及微拉伸台对奥氏体 -贝氏体球墨铸铁裂纹萌生、扩展的微观过程进行了跟踪观察。结果发现 :受拉时微裂纹首先在石墨 -基体界面上萌生 ,并沿界面扩展 ;基体中的裂纹多数是沿贝氏体铁素体 -奥氏体界面扩展 ,不同取向的基体组织可使裂纹偏转或分叉 ;主裂纹扩展过程中前方始终存在石墨 -基体界面的开裂。此外 ,还根据实验结果进一步分析了奥氏体 -贝氏体球墨铸铁的强韧化机理更多还原

【Abstract】 The micro process of crack initiation and propagation in austempered ductile iron has been investigated by scanning electron microscope with a micro tensile stage. It was revealed that the micro cracks always initiate at the graphite matrix interface and then propagate along the graphite matrix interface. The micro cracks in matrix propagate along the bainitic ferrite austenite interface. The crack deflection or branching is occurred due to the different orientation of bainitic ferrite. The graphite matrix interface is cracked in the front of main crack during propagation. The mechanism of strengthening and toughening in austempered ductile iron is further discussed according to these observations.更多还原