Time-dependent notch sensitivity of Waspaloy was observed at test temperatures from 1000 to 1300 deg F. Its occurrence in this range was dependent on the heat treatment. “Overaging” eliminated the notch sensitivity. Optimum combination of smooth and notched specimen strengths for material solution treated at 1975 deg F were obtained by aging 24 hr at 1550 deg F. Necessary conditions for time-dependent notch sensitivity were (i) the notch specimen loads had to be below the approximate 0.2 percent off set yield strength; and (ii) test data from smooth specimens had to indicate that small amounts of creep used up large fractions of creep-rupture life. No reasons were evident why these criteria will not prove applicable to other alloys.

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