Tensile strengthening in the nickel-base superalloy IN738LC

The tensile properties of superalloy IN738LC with different precipitate mic rostructures are evaluated at room temperature, 650 degrees C, 750 degrees C, and 85 degrees C at two different strain rates. The properties can be pr esented in two groups based on the comparable closeness of the values obtai ned-those of microstructures C and M, with coarse and medium size precipita tes, and those of microstructures F and D, with fine and duplex size (mediu n + fine) precipitates. Preferred orientations, lattice parameters, and met allography are used to characterize the microstructure and tensile testing to determine the yield strength, tensile strength, and strain hardening coe fficients. An anomalous increase in yield strength is observed, which occur s at temperatures about 100 degrees C higher with higher strain rate than w ith lower strain rate applied. The experimental results show that the yield strength is influenced by preferred orientations and precipitate size, whi le the tensile strength is effected by the size and morphology of precipita tes.