Alloy 182 is an austenitic (FCC) nickel base Ni-Cr-Fe-Mn weld metal that is used as a weld filler or weld pad metal to join stainless steel reactor internals, reactor instrumentation penetrations and main coolant piping to the low-alloy steel reactor pressure vessel. Stress corrosion cracking (SCC) in alloy 182 dissimilar welds is one of the most important material degradation problems and an ongoing issue in boiling (BWR) and pressurized water reactors (PWR) world-wide with potential safety concerns.
Thermally activated preferential local ordering (unlike atom pairs is greater than that in a random solution) of elements within a lattice, over spatial dimensions that are typically on the order of a few nearest neighbor spacing 20 to 50 Å (2 to 5 nm) is referred as short range ordering (SRO). SRO causes lattice contraction and induces additional stress which is claimed as the driving force for SCC in the alloy 600, alloy 690, and alloy 182.