Abstract
Stress corrosion cracking behavior around the interface between nickel base alloy (Alloy182) and low alloy steel (LAS) was investigated by modified large-scale CBB test method in high temperature oxygenated water. In the smooth test pieces, oxides formed in LAS or cracks propagate along the interface in pure water (<0.1 μS/cm at inlet), on the other hand, a crack propagated deeply into LAS in the environment where conductivity was controlled to approximately 0.3 μS/cm at inlet by Na2SO4 injection. In the latter case, the surface crack penetrates the width of the test pieces so that the mechanics conditions were thought to be severe. In notched test pieces, it was observed that cracks propagated into LAS and also oxides formed in the pure water. There was a tendency that the crack depth and the diameter of oxide increase with thickness of Alloy 182 increasing. The effect of applied strain and sample preparation direction to the welding direction on SCC behavior around the fusion interface was investigated, but there is no significant difference in the morphology by applied strain and sample preparation directions.
