Corrosion of path A PCA, type 316 stainless steel and Fe-12 Cr-1 MoVW steel in flowing lithium

Results from lithium thermal-convection loop (TCL) experiments with the path A prime candidate alloy (PCA), type 316 stainless steel, and Fe-12 Cr-1 MoVW are presented. The short-term (< 3050 h) weight losses of PCA in flowing lithium were just slightly higher than those of type 316 stainless steel and may be attributable to the higher nickel concentration of PCA. The corrosion response of PCA specimens was not affected by cold work. A surface analysis of type 316 stainless steel specimens exposed in the hot leg of a TCL for over 7000 h confirmed earlier observations regarding preferential leaching of nickel and chromium and deposition of pure chromium. These analyses also showed that exposure temperature strongly affects surface porosity and that molybdenum enrichment occurs on surfaces undergoing dissolution. Weight loss data as a function of time for Fe-12 Cr-1 MoVW steel exposed to lithium at 5000C yielded the same dissolution rate as the steady-state value for nickel-depleted type 316 stainless steel. Significant weight losses were measured in the cold leg of this loop, and they appeared to be related to chromium depletion (possibly as a result of impurity reactions)