Experimental and numerical investigations on the influence of cold expansion on low cycle fatigue life of bolt holes in aeroengine superalloy disk at elevated temperature

The direct mandrel cold expansion was introduced to bolt hole locations for a nickel based superalloy compressor disk of an aeroengine in order to improve its fatigue performance at elevated temperature. Low cycle fatigue tests on plate specimens were carried out at 600 degrees C, revealing the average lives of cold expanded samples increased by 2.1-3.5 times. Fracture surfaces were examined using the scanning electron microscope, together with the X-ray diffraction method to measure the residual stresses. Based on three-dimensional finite element analysis, the proposed life model gave satisfactory results with the maximum mean absolute error being 25.7%.