Microstructure and corrosion behavior of the heat affected zone of a stainless steel 308L-316L weld joint

Microstructure of the heat affected zone (HAZ) of a 308L-316L stainless steel (SS) weld joint and its corrosion behavior in high temperature water were studied. Peak of the residual strain was observed to approach to the fusion boundary in the HAZ while the strain increased from the top to root areas of the HAZ. The root area of the HAZ shows a lower corrosion resistance in high temperature water than the top and middle areas of the HAZ. This is attributed to a higher level of residual strain in association with a higher density of tangled dislocations in the top area of the HAZ. The results suggest that the residual strain in the HAZ could also promote the SCC through its effect on corrosion, in addition to that on the local microstructure and mechanical property of the steel.