Dependence of crack growth kinetics on dendrite orientation and water chemistry for Alloy 182 weld metal in high-temperature water

Stress corrosion cracking growth rates of Alloy 182 weld metals in T-S and T-L orientations in 288 °C pure water with various dissolved oxygen and hydrogen concentrations were measured. Extensive inter-dendritic stress corrosion cracking paths on the side surfaces and fracture surfaces were observed. The crack growth path in the T-S orientation specimen was perpendicular to the applied loading direction, and parallel to the loading direction in the T-L specimen. Crack growth rates of the T-S specimen were significantly higher than those of the T-L specimen under the same test conditions. The crack growth rate decreased significantly with decreasing dissolved oxygen concentration. Adding dissolved hydrogen in water caused an apparent decrease of the alternating current potential drop signal during crack growth monitoring.