球墨铸铁疲劳裂纹扩展的微观机制  

MICROMECHANISM FATIGUE CRACK PROPAGATION OF DUCTILE IRON

作　　者：于功利[1] 张维平[1] 韩万有[1] 郑贤淑[1] 金俊泽[1] 

机构地区：[1]鞍钢钢铁研究所,大连理工大学

出　　处：《机械工程学报》1994年第5期35-39,共5页Journal of Mechanical Engineering

摘　　要：研究了在恒幅拉伸循环载荷作用下球铁的疲劳裂纹扩展的微观机制，分析了石墨形态对铸铁疲劳裂纹萌生及扩展行为的影响。结果表明：铸铁的石墨形态对疲劳裂纹的萌生及扩展有很大影响。灰铁由于在共晶团内石墨片相互连接，疲劳裂纹总是沿着与外应力相垂直的石墨片／基体边界扩展。球铁的疲劳裂纹扩展受基体组织及石墨形态所左右，但在石墨球／基体界面产生的滑移带、塑性区及裂纹尖端钝化区决定着疲劳裂纹萌生及扩展的整个过程。球铁的疲劳裂纹扩展规律是：裂纹连续扩展—急速扩展—裂纹尖端钝化—重新诱发裂纹—连续扩展。The micromechanism of fatigue crack propagation of ductile iron is investigated by the action of constant amplitude and tensile cycle load. The effect of graphite morphology on initial crack and propagation behavior of fatigue crack is analysed. The results show that graphite morphology of cast irons had great effects on initial fatigue crack and propagation behavior. Because of the interconnect of graphite flakes in the grey iron's eutectic cells, fatigue crack always propagated along graphite flake-matrix interface, which is perpendicular to outer stress. The graphite flakes constitute the majorities on the fracture surface, so fatigue crack propagation for grey iron was mainly restricted by grap hite flakes. Fatigue crack propagation for duetile iron is influenced by matrix structures and graphite morphology, but the initial fatigue crack and the whole propagation process are determined by plastic zone, crack tip passivation zone, and slip band produced on the spherodial graphite-matrix interface. The regular pattern of fatigue crack propagation of ductile iron is as follows: cracks' continuous propagation in the matrixes-rapid propagation-crack tip blunting-bringing out cracks-continuous propagation of the cracks.

关 键 词：球墨铸铁 疲劳裂纹 微观机制 

分 类 号：TG143.5[一般工业技术—材料科学与工程]