Abstract: Using the results from the studies in C-Mn steel ductile fracture mechanisms and the rules of the stress-driven mi-gration of point defects to a crack, the authors try to investigate the possible relation between fracture toughness Kc and temperature. This relation seeme in good as compared with the results from the experiments performed by several foreign researchers and the authors of this paper, who tested BHWi5 steel at temperatures from 80℃ to 350℃.In the end of the paper, a parameter called stress-state-parameter. This proposed to take count of the effect of stress state on ductile fracture. All the results and the Kc-T relations given in this paper may be useful in engineering design and defect assessment.

Key words: 点缺陷, 断裂力学, 断裂韧度, 韧性断裂, 应力状态参数