Relationship of Mechanical Characteristics and Microstructural Features to the Time-Dependent Edge-Notch Sensitivity of Inconel 718 Sheet

Abstract

Time-dependent notch sensitivity of Inconel 718 sheet was observed at 900 deg F to 1200 deg F (482–649 deg C). It occurred when edge-notched specimens were loaded below the yield strength and smooth specimen tests showed that small amounts of creep consumed large rupture life fractions. The severity of the notch sensitivity was reduced by decreasing the temperature of the solution treatments, increasing the time and/or temperature of aging and increasing the test temperature to 1400 deg F (760 deg C). Elimination of time-dependent notch sensitivity correlated with a change in dislocation motion mechanism from shearing to bypassing precipitate particles.