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Chloridation-oxidation of commercial austenitic alloys at 800 C

Book ·
OSTI ID:376071
;  [1]
  1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering
Alloys 304, 800 and 600, with increasing Ni content, are commonly used austenitic alloys. Chloridation-oxidation studies of these alloys were carried out at 800 C in three different H{sub 2}-HCl-H{sub 2}O(v) environments: (a) both low HCl and H{sub 2}O(v) partial pressures, where either Cr{sub 2}O{sub 3} or FeCr{sub 2}O{sub 4} is stable, (b) both high HCl and H{sub 2}O(v) partial pressures, where FeCr{sub 2}O{sub 4} is stable and CrCl{sub 2} is metastable, and (c) high HCl partial pressure in the absence of H{sub 2}O, where either CrCl{sub 2} or Cr{sub 2}O{sub 3} is stable. Although alloy 600 has the lowest Cr content of these three alloys, it showed excellent corrosion resistance in all three environments because of its high Ni content. Alloy 304, with the lowest Ni content of the three alloys, exhibited poor corrosion resistance in the environment C, fair resistance in the environment B and good resistance in the environment A. Alloy 800 showed very good resistance in Environment A, and fair corrosion resistance in Environment B; however, it suffered linear weight-loss kinetics when exposed to Environment C. Different corrosion mechanisms are proposed for the alloys according to the different environments. Preliminary testing of six other commercial Ni-base austenitic alloys was carried out in the severe environment of 90%H{sub 2}-10%HCl at 800 C. Differences in evaporative reaction rates were observed, but mechanistic interpretation must await further characterization of the corroded coupons.
OSTI ID:
376071
Report Number(s):
CONF-960389--
Country of Publication:
United States
Language:
English