Stress corrosion cracking of alloy 52/152 weldments near dissimilar metal weld interfaces

Abstract

Recent stress corrosion cracking (SCC) crack growth rate (CGR) testing at Argonne National Laboratory (ANL) of Alloy 52/152 weldments near dissimilar metal weld interfaces have found, on occasion, some rather surprisingly high SCC CGRs. Weld overlays of alloys believed to possess superior SCC resistance due to their higher Cr content are typically applied over welds made with SCC-susceptible alloys with the expectation that they will act as a barrier to SCC. However, testing conducted at ANL revealed that the SCC CGRs near the interface between the two welds was in the 10 −10 m/s range. Likewise, SCC CGR data in Alloy 152 weld butter near the interface with Low Alloy Steel, which is a region with some dilution of Cr, found SCC rates as high as 10 −10 m/s. In most cases, SCC propagation occurred in a direction perpendicular of that of the dendritic grains—a direction not usually associated with fast SCC propagation. The objective of this paper is to present and discuss the testing results with a focus on the possible paths for fast IG SCC propagation in these weldments.