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Corrosion of alloy 718 in a mercury thermal convection loop

Technical Report ·
DOI:https://doi.org/10.2172/750987· OSTI ID:750987

Two thermal convection loops (TCLs) fabricated from annealed alloy 718 continuously circulated mercury (Hg) with 1000 wppm gallium (Ga), respectively, for about 5000 h, duplicating previous TCL tests for annealed 316L. In each case, the maximum loop temperature was 305C, the minimum temperature was 242C, and the Hg flow rate was approximately 1.2 m/min. Unlike the 316L exposed to Hg, which above about 260C exhibited a thin, porous surface layer depleted in Ni and Cr, the alloy 718 coupons revealed essentially no wetting and, therefore, no interaction with that Hg at any temperature. Alloy 718 coupons suspended in the loops revealed inconsequentially small weight changes, and both the coupons and loop tubing exhibited no detectable metallographic evidence of attack.

Research Organization:
Oak Ridge National Lab., Oak Ridge, TN (US)
Sponsoring Organization:
USDOE Office of Science (US)
DOE Contract Number:
AC05-96OR22464
OSTI ID:
750987
Report Number(s):
ORNL/TM-1999/323
Country of Publication:
United States
Language:
English