Sensitization Condition of Alloy 182 Welds Joined by Stainless Steel 304 and Low Alloy Steel SA 508

In this paper, sensitization condition of dissimilar metal welds (DMWs) with Alloy 182 joined by stainless steel 304 and low alloy steel SA 508 grade 3 class 1 was defined. The materials have been used in surge line nozzle in old nuclear power plants which needs steady monitoring using NDE based on cracking experience in Wolf Creek, Farley 2, and so forth. The sensitization heat treatment at 600 .deg. C for 48 hours is decided to the most sensitized condition for Ni base Alloy 182 welds joined by stainless steel 304 and low alloy steel SA 508 Gr.3 Cl.1 through modified Huey test and modified DL-EPR test. Two tests have a good agreement. The surface morphology of specimens after modified Huey test shows a sharp and deep intergranular attack, which means the more chromium is depleted, the more specimen is corroded. On the other hand, the surface morphology of specimens after modified DL-EPR test shows a wide and shallow attack which means uniform corrosion occurs if Cr depletion is less than the critical content.