G-m界面断裂对灰口铸铁力学行为及性能的影响

The Influence of G-m Interfacial Fracture on the Mechanical Behaviour and Property of Grey Cast Iron

用扫描电镜原位观察技术，发现拉伸早期形成的Ｇ－ｍ界面断裂并不是直接连续扩展成主裂纹，而是逐步再生许多界面裂纹，其间基体韧带缩小而形变裂开将界面裂纹连接起来这些过程局限在裂开前主裂纹及其近邻处很窄的微带区内进行在断口或表面裂纹中，Ｇ－ｍ界面断裂占绝大部份。

By using the technique of observation in situ under scanning electron microscope, it was found that under tensile loading the G-m interfacial crack formed in the early stage was followed by many interfacial cracks nucleating again gradually instead of its continuously propagating to form a main crack directly The matrix ligaments between interfacial cracks, theerfore, narrowed and deformed to join the interfacial cracks together These happened only within the micro zone of main crack before cracking and the narrow micro zone adjacent to main crack Based on an estimate, most fractograph or surface crack is of the G-m interfacial crack instead of the transgrainular fracture of the matrix ligament According to that, a new explanation of the relation between G and properties in grey cast iron is proposed