抄録
The evaluation procedure of cleavage mode fracture toughness is discussed on the basis of combined elastic-plastic fracture methodology, AE (Acoustic Emission) technique and statistics, where the AE method determined the onset of microscopic cleavage pop-in cracking. The intergranular cleavage fracture toughness data obtained for temper-embrittled Cr-Mo-V steel at 150°C were mainly analysed for the probabilistic aspect, and their size effects were also discussed. The main results are : (1) Population of the intergranular cleavage pop-in fracture toughness could be represented by a three parameter Weibull distribution function. (2) Distribution of the intergranular cleavage fracture toughness on large specimens can be predicted by the fracture toughness data using small specimens which satisfy a size requirement, B>150·(Jc/σY), and this is also applicable to the evaluation of transgranular cleavage fracture toughness. (3) A probabilistic procedure for predicting a lower bound cleavage mode fracture toughness is proposed based on the above results.
