Abstract
In this study, an equivalent CTOD concept was proposed on the basis of the local approach. This concept was born to consider the transferability of 3-point bend CTOD results to fracture performance evaluation of structural components. The equivalent CTOD was defined as the CTOD at which the 3 -point bend specimen and the structural component provide the compatible Weibull stress. The fracture performance of a wide plate with a surface notch predicted by the equivalent CTOD concept was consistent with the experimental result. On the other hand, the analysis based on the conventional CTOD concept gave very conservative estimation of the fracture performance of the wide plate.
A new procedure for fracture toughness requirement was presented based on the equivalent CTOD concept. It was pointed out that the equivalent bend CTODδR3P to meet the required deformability of the wide plate was much smaller than the required CTOD δRWPfor the wide plate. The equivalent CTOD concept was effective to quantify the strength mis-match effect between the base and weld metals on the required fracture toughness of the weld metals. The required weld metal CTOD δδRWP for the wide plate increased with decreasing the yield strength mis-match ratio σWY/σBY between the base and weld metals. By contrast, the required bend CTOD δR3Pof the weld metal was not always affected very much by the mis-match condition in welds.
