| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in the conventional technique that further reduction in the SCC(stress corrosion cracking) sensitivity of an NCF750 alloy under the high stress condition is still required although the SCC resistance of NCF750 alloy is already improved. SOLUTION: An NCF750 alloy is heated at 1,000-1,100 deg.C for desired time to undergo solution heat treatment, heated at 650-750 deg.C for >=10 h and air cooled to undergo aging treatment, and further subjected, one or more times, to aging treatment consisting of heating at 650-750 deg.C for >=10 h and air cooling. By the above procedure, the precipitation ofγ'-phase and Cr23C6 in a matrix of austenitic phase is accelerated and SCC under high stress condition in high temperature water is suppressed. The above problem can be solved by carrying out these heat treatments and providing the NCF750 alloy to which the heat treatments are applied and also providing a structural member composed of the NCF750 alloy to which the heat treatments are applied.
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