SCC Retardation and Propagation Behavior in Dissimilar Weldment of Alloy 182 and Low Alloy Steel

摘要

SCC crack propagation and retardation behavior near fusion boundary of Alloy 182 and low alloy steel (LAS) was studied. Alloy 182-buttered A533B and SQV2A weldments were prepared to simulate weld overlay in BWR bottom region. Compact tension (CT) and contoured double cantilever (CDCB) specimens, which included fusion boundary, were cut out from the weldment so that the direction of machined notch would be perpendicular to fusion boundary. Pre-fatigue was introduced, controlling its crack tip to be 2 or 3 millimeters from fusion boundary. SCC propagation tests were carried out under constant and trapezoidal-wave loading modes in simulated BWR environment. The crack growth behavior during SCC test was monitored by the potential drop method. After the test, morphology of cracks was observed in cross-section of the specimen and in fracture surface after post-cracking to confirm whether the crack traverses the fusion boundary or not.