Fatigue behavior of coated and uncoated cast Inconel 713LC at 800 degree C

Cylindrical specimens of Inconel 713LC in as-received condition and with surface treatment by Al diffusion coating were cyclically strained under strain control at 800 degree C in air. Surface treated layer was characterized and the hardness depth profile was measured. Cyclic stress-strain response and fatigue life of both materials were assessed. The stress response of the coated superalloy specimens is lower in comparison with the untreated specimens. Beneficial effect of surface treatment on the Manson-Coffin curve is documented. Specimen sectioning and fracture surface studies revealed fatigue damage mechanisms both in coated and uncoated specimens. Propagation path of the principal crack is predominantly interdendritic.