Cross-Weld Creep Comparison of Power Plant Steels CrMoV, P91 and P92

Results obtained from high temperature creep tests of ferritic steel CrMoV, P91 and P92 cross-weld specimens are compared. Data are presented normalized with the results of the corresponding parent metals in order to compare the materials tested at different temperatures and stresses, and to identify characteristic cross-weld material trends. All cross-weld failures occurred in the heat-affected zone (HAZ) adjacent to the parent metal, known as type IV, at earlier test durations than for the parent material specimens. The relative performance of the cross-welds was found to decrease with decreasing stress. The CrMoV cross-weld specimens showed by far the lowest weld strength reduction factors and greatest notch strengthening, determined by testing uniaxially loaded bars with semicircular circumferential notches located in the heat-affected zone. The P91 and P92 cross-weld specimens were found to have similar (high) weld strength reduction factors and showed little or no notch strengthening. The failure time of a P92 cross-weld specimen relative to the P92 parent material could be estimated using data from P91 cross-weld and relative parent material tests.