13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- The above research showed that defects of pencil-point shaped fracture usually in center of wire, therefore the procedure of microscopic analysis and metallographic examination should be: (1) SEM was used to search inclusion or pin of it in conical tip. (2) Longitudinal metallographic examination was used to seek central brittle phase. Transversal metallographic examination was also used by some researchers to judge brittle microstructure. Longitudinal metallographic examination was suggested that could found brittle phase and its discontinuous deformation (shown in Fig. 3) more easily. (a)conical tip (b) conical hole Figure. 1 Morphology of pencil-point shaped fracture (a) Inclusion (b) net carbide (c) martensite (longitudinal) (d) martensite(transversal) Figure. 2 Central brittle microstructure of pencil-point shaped fracture
RkJQdWJsaXNoZXIy MjM0NDE=