1985 Volume 3 Issue 1 Pages 82-89
Fracture toughness testing of heat-affected zone, especially grain coarsened zone, in welds is considerably difficult compared with weld metal and base metal, because the embrittlement of HAZ causes in the localized region. However, grain coarsened HAZZ is usually the most embrittled region in welds, it is often required to evaluate fracture toughness of its region itself.
In the present paper, a probabilistic procedure for evaluating fracture toughness of the localized embrittlement region has been proposed newly, based on the weakest link model. By means of this procedure, distribution of cleavage toughness of localizedt embrittlement region, e.g. grain coarsened HAZ, is proved to be analyzed from test results on specimens of which notch is located in weld metal and base metal, respectively, and cross-bond-type notched specimens which have localized embrittlement region at notch front.
Moreover, the sufficient number of cross-bond-type notched specimens which are necessary to evaluate fracture toughness of localized embrittlement region itself according to our present procedure has been investigated. By using 20 or more cross-bond-type notched specimens, cleavage toughness of the localized embrittlement region can be grasped.