High temperature low cycle fatigue of inconel MA 6000

Abstract

Inconel MA 6000 is an oxide dispersion and gamma'strengthened nickel base alloy and a candidate material for demanding high-temperature applications in corrosive environments. Its fatigue behaviour, which is not well documented, is explored in a collaborative action within the ODS Group of COST 501. Cyclic deformation curves, cyclic stress-strain curves and cyclic life data are reported as a function of the applied strain-rate for the temperature range 760°C-1050°C. At 850°C the high strain fatigue results are correlated with high cycle fatigeu data and compared to the performance of IN738LC. Microstructural analysis, in combination with the fatigue data, shows a transition to homogeneous deformation at approximately 800°C and a change from transgranular to mixed trans/intergranular failure at around 1000°C, which is thought to be triggered by environmental attack. The initiation of cracks appears to take up a considerable fraction of the cyclic life.