Elevated-temperature creep-fatigue crack-growth behavior of nickel-based HAYNES® R-41, HAYNES® 230® and HASTELLOY® X alloys

Abstract

The fatigue-crack-growth (FCG) experiments were performed on the nickel-base HAYNES R-41, HAYNES 230 and HASTELLOY X superalloys at temperatures ranging from 760°C to 927°C The crack length was measured using a direct current potential drop technique. A triangular waveform of 0.333 Hz and a load ratio of 0.05 were employed under a constant-load-range control mode in the FCG tests. The various tensile hold times were imposed at the maximum load in the FCG tests to investigate fatigue and creepfatigue interactions. It was found that the introduction of hold time and the increase of temperature led to a considerable increase in the cyclic-crack-growth rate. The fracture surfaces were investigated to determine the crack propagation mode using scanning electron microscope. Furthermore, the crack-growth rates of three superalloys were compared.