High temperature fretting fatigue behavior of IN100

Fretting fatigue behavior of a nickel-base superalloy, IN100, was investigated at 600 °C. Fretting fatigue tests were conducted at various stress levels using cylinder-on-flat contact configuration. Effects of microstructure were also investigated by varying the gamma grain size (3 μm versus 7 μm). Additionally, effects of contact load were studied. Furthermore, plain fatigue tests of IN100 with two microstructures were also conducted. Fretting reduced the strength/life in comparison to those of the plain fatigue almost equally in both microstructures. Increase of contact load reduced the fretting fatigue strength/life. An increase of the gamma grain size decreased the fretting fatigue strength/life of IN100. Fracture surfaces of the 3 μm grain microstructure showed intergranular and tortuous crack path while the 7 μm grain microstructure had transgranular and relatively smoother crack path. Fractographic analysis indicated that the 3 μm grain microstructure had a higher resistance to the fretting fatigue crack nucleation and initiation as well as to the crack growth in comparison to the 7 μm grain microstructure, which was in agreement with the observed plain and fretting fatigue behaviors. Furthermore, plain and fretting fatigue performances improved at 600 °C in comparison to room temperature with both microstructures.