The role of grain structure in the creep and fatigue of ni-based superalloy PM 1000

A study of the monotonic and cyclic deformation behavior of the recently developed oxide-dispersion-strengthened, nickel-based superalloy PM 1000 was carried out at temperatures up to 1200 deg C in air. The influence of grain structure and texture was investigated using two heats with an identical particle microstructure--a < 100 > -fiber-structured bar material with a grain aspect ratio of ten along the longitudinal direction and a pancake-structured sheet material with a grain aspect ratio of four and a < 100 > {011}-cube on edge texture. Both creep resistance and lifetime in cyclic deformation depend strongly on texture and weakly on the grain aspect ratio, which determines the fracture path. Instead, lifetime can be predicted on the basis of the different Young's moduli in the longitudinal and longitudinal-transverse direction, respectively. Comparisons are made with alloy MA 754.