摘要
用扫描电镜对合有破碎状铁素体的珠光体球铁进行拉伸断裂过程的动态观察,研究裂纹萌生、扩展与石墨球、铁素体、珠光体组织的关系。结果表明,断裂过程为石墨球与基体脱开;基体局部塑性变形;显微裂纹萌生;若干显微裂纹连成较长的裂纹,并与扩展的主裂纹前端相连接。断裂前铁素体比珠光体承受更大的塑性变形,铁素体有效地钝化显微裂纹,其作用随铁素体量增加而加强。和牛眼状铁素体比,破碎状铁素体可使裂纹扩展经历更多曲折,路径相应增长,消耗能量增加。
The tensile fracture crack behaviour of pearlitic ductile cast iron containing various amounts of broken ferrite was observed using SEM. The relationship between crack initiation and propagation versus structure of graphite nodules, ferrite and pera-lite was investigated. The results revealed that the processes of crack initiation and propagation were, decohesion between the graphite nodules and the matrix, localized plastic deformation in the matrix, micro-crack initiation at many nodule sites, the linkup of microcracks and the primary crack front. The ferrite can bear more plastic deformation than the pearlite before fracture. The ferrite can blunt the microcracks which strengthen with ferritic quantity, especially broken ferrite, compared with bull's-eye ferrite, crack propagation path is more tortous and more energy are consumed in the fracture process of cast iron.
出处
《铸造》
CAS
CSCD
北大核心
1990年第6期9-12,共4页
Foundry
