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Effects of cold work, sensitization treatment and its combination on corrosion behavior of stainless steels in nitric acid

Book ·
OSTI ID:548558
; ;  [1]
  1. Central Research Inst. of Electric Power Industry, Komae, Tokyo (Japan)
In the Purex reprocessing process, the spent nuclear fuels from light water reactors are dissolved in nitric acid to separate and recover the fissile materials such as Uranium and Plutonium from the radioactive fission products. To ensure safety and reliable operation of the reprocessing plant, superior corrosion resistance is required to the structural materials of the plant, and stainless steels have been used as one of the main structural materials because of its very good performance in a nitric acid environment. Corrosion behavior of stainless steels was investigated in nitric acid for the effect of cold work, sensitization heat treatment and its combination. Corrosion rate of solution-treated Type 304 with extra low carbon (304 ELC) increased with time and reached constant values after 1,000 h of immersion time. Constant corrosion rates, however, were obtained for 25Cr-20Ni-Nb (310 Nb) from the initial stage of immersion. Cold work mitigated corrosion of the solution-treated stainless steels. The effect of cold work was different on the two stainless steels with sensitization heat treatment, showing accelerated corrosion for 304 ELC. The corrosion resistance of 310 Nb was superior to 304ELC after all the treatments. Chromium concentration of the sensitization treated 304 ELC was lower in the grain-boundary region than that of the solution-treated one, although no chromium carbide precipitation was observed. This might be the cause of corrosion enhancement by sensitization treatment.
OSTI ID:
548558
Report Number(s):
CONF-970332--
Country of Publication:
United States
Language:
English