results are shown in Figure 4 by comparing OC values obtained from test by using Eq.(l) with the weld bead heat-

results are shown in Figure 4 by comparing OC values obtained from column quarter part bend test by using Eq.(l) with the weld bead heataffected-zone (HAZ) CTOD toughness, which is estimated from the chemical compositions and hardness of column materials using Aihara's method (1992). The tendency is nearly the same between them, although the estimated HAZ CTOD is relatively low. The discrepancy can be caused by the fact that the plastic constraint is relatively low for the column test because of a shallow notch (1~3mm depth) and in column test fracture occured by the condition of 0 ~ 0 c, that means the results could estimate higher critical CTOD values than the actual ones.