Assessment of Fatigue Resistance of Aluminide Layers on MAR 247 Nickel Super Alloy with Full-Field Optical Strain Measurements

摘要

This work presents the results of fatigue tests of MAR 247 alloy flat specimens with aluminides layers of 20 or 40 mu m thickness obtained in CVD process. Fatigue test was conducted at amplitude equal to half of maximum load and ranging between 300 and 650 MPa (stress asymmetry ratio R = 0, frequency f = 20 Hz). Additionally, 4 of the tests, characterized by the highest amplitude, were accompanied with non-contact strain field measurements by means of electronic speckle pattern interferometry and digital image correlation. Results of these measurements allowed to localize the areas of deformation concentration identified as the damage points of the surface layer or advanced crack presence in core material. Identification and observation of the development of deformation in localization areas allowed to assess fatigue-related phenomena in both layer and substrate materials.