抄録
It is well known that the cleavage fracture toughness of steels deteriorates by pre-straining. Quantitative prediction of fracture toughness after pre-strain was examined in this work. Based on the local fracture criterion approach, the cleavage fracture toughness of steels can be described in terms of the cleavage fracture strength and the yield strength of the materials. Since the experimental cleavage fracture strengths before and after pre-strain were almost constant, deterioration in fracture toughness can be attributed to the work hardening behavior of the base steel. The predicted fracture toughness successfully agreed with the experimental results. The effect of the yield ratio on the deterioration in cleavage fracture toughness was also investigated. The experimental results in fracture toughness showed larger deterioration in lower yield ratio steel and showed the saturation under the relatively high pre-strain. These tendencies could be qualitatively described with the numerical analysis based on the local fracture criterion approach.
