EVALUATION OF CTOD FRACTURE-TOUGHNESS OF HT80 STEEL WELDMENTS BY STATISTICS

The CTOD fracture toughness of the through thickness notched specimens was investigated for HT80 quenched and tempered steel weld metals. Weibull statistics is applied to interpret the CTOD testing results of heat affected zones and corresponding weld metals. The CTOD scatter characteristics are related to the Weibull shape parameter. The thickness effect and the size effect of coarse grained heat-affected zone (CGHAZ) are estimated based on the weakest link model. The mean CTOD value decreases with increasing specimen thickness while the lower bound value is unaffected by specimen thickness. The estimated CGHAZ size effect on the mean CTOD fracture toughness agrees with experimental data.