摘要
应用透射电子显微术研究淬火过程及拉伸加载过程,低碳马氏体钢中形成的显微组织。淬火的马氏体中出现形变带。随着拉伸变形度的增加,自回火碳化物界面放出位错,在碳化物周围形成位错缠结。在马氏体晶条界附近及整个容积中均形成高密度的位错缠结。马氏体晶条拉长、弯曲和扭转。所有这些变化都是加工硬化的重要根源。钢的断裂单元主要是马氏体晶条。
The microstructures in a low carbon martensite formed after quench hardening
and tensile loading have been investigated by using transmission electron microscopy. Deformation bands are formed in the as-quenched low carbon martensite. With increasing tensile strain, the dislocation density in low carbon marteasite are clearly increased. The interfaces of the self-tempered carbides release dislocations, and the dislocation tangles are formed around carbides. The high density dislocation tangles are formed at lath boundary and within
martensite lath. The martensitic laths are elongated, curved and twisted. All the microstructure variations are important sources for work-hardening of the steel. The fracture unit of the specimen is the martensite laths.
