Fracture surface microstructure and new fracture mechanism in the pearlite structure
Kai Zhai, Yujing Zhang, Jialong Yue, Yong Qiu, Xinru Zhou, Ke Zhao, Xiaomei Yu, Jin You Zheng, Songjie Li, Dehai Ping
Abstract
The fracture behaviours of pearlite structures in several typical carbon steels were investigated by scanning electron microscopy (SEM). Microstructural analysis indicated that the fracture of pearlite is a mixed ductile-brittle fracture, and brittle fracture has cleavage fracture characteristics, which often occur inside the pearlite structure. The fracture surface can exhibit any orientation relationship with the ferrite/cementite interface plane in the pearlite structure. The two phases in the pearlite structure (ferrite (α-Fe) and cementite (θ-Fe3C)) are fine grains rather than single-crystal platelets. The cleavage fracture mechanism in any direction of pearlite structure occurs due to the fine grain substructure.