Abstract
Stress corrosion cracking (SCC) behavior near the fusion boundary of dissimilar weld joint with Alloy 182-A533B low alloy steel (LAS) in high temperature water have been investigated focused on the relationship between the crack pass and characteristics of microstructure. It has been observed that spherical and crack-like oxides were formed in LAS. From the results of metallographic observation of the SCC specimens, cracks in Alloy 182 propagated along the dendrite grain boundary, and crack-like oxides in LAS propagated along the prior austenite grain boundary in coarse-grained heat-affected zone. It has been suggested that the continuousness between dendrite and prior austenite grain boundary across the fusion boundary, namely the continuousness of crack pass, affects the SCC behavior in LAS. Possible effect of multiple heat cycle of welding process on the formation of the continuous grain boundary has also been suggested.
