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U.S. Department of Energy
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Treatment of Alloy 600 tube-tube sheet transitions for improved resistance to primary water SCC I. Performance of baseline as-expanded samples in 750/sup 0/F steam

Conference ·
OSTI ID:6976957

Mill annealed Alloy 600 tubing samples were mechanically expanded (hard rolled) into steel collars using standard manufacturing techniques. The rolled specimens contained transitions from unexpanded to expanded tubing that were representative of those in as-fabricated nuclear steam generators. A specially fabricated heat of Alloy 600 tubing in two standard sizes was used. This special tubing exhibited a high susceptibility to primary water stress corrosion cracking (PWSCC) in tests of reverse U-bends in 750/sup 0/F (400/sup 0/C) steam with hydrogen. The expanded samples were shown in relatively prolonged exposures to the steam condition to develop axial intergranular stress corrosion cracks on the inner tube surfaces in the transition regions. It is concluded that the samples and the steam condition constitute a useful combination in evaluating the benefits of treatments to improve the PWSCC resistance of as-expanded mill annealed Alloy 600 transitions.

OSTI ID:
6976957
Report Number(s):
CONF-870314-
Country of Publication:
United States
Language:
English