Abstract
J integral, KIC and COD values were measured and compared with each other on four structural steels, HT80, HT60, KD32 and SM41C. These fracture toughness parameters were obtained through three-point bend tests conducted at low temperatures varying from liquid nitrogen temperature to 0°C.
The main results obtained are as follows:
1) The KIC value calculated from JIC is in good agreement with that obtained according to ASTM standard.
2) The COD value calculated from J integral value through Dugdale's model is approximately 1.4 times the empirical one regardless material, specimen thickness and temperature.
3) Equivalent energy method using JC value gives a good estimation of fracture stress of a deepnotched, tensile specimen.
4) Fracture stress calculated from KIC or J integral value is greater than that from a COD value through Dugdale's model. The difference between them becomes greater as the plate thickness becomes greater and the temperature lower.
