THE INFLUENCE OF GRINDING BURN DAMAGE ON THE FATIGUE BEHAVIOUR OF NIMONIC C1023

摘要

An assessment of the fatigue behavior of ground Nimonic C1023 is presented. Specimens were produced by cylindrical plunge grinding and tested using rotating bending fatigue machines. Initially, the behavior of unburnt, 'sparked-out' specimens was to be compared to that of severely burnt specimens. The burn damage was investigated using hardness tests and microscopic examination and the chemical damage was found to be less severe than damage previously observed in creep-feed grinding workpieces; surface cracks observed in creep-feed burn were not found in the fatigue specimens and it is suggested that it was the size and geometry of the specimens which prevented their formation. The damage was limited to surface discoloration and a subsurface softening. This caused an insignificant reduction in fatigue performance which suggests that the present rejection criterion of surface discoloration for ground Nimonic components is too conservative.