The effect of inclusion factors on fatigue life and fracture-mechanics-based life method for a P/M superalloy at elevated temperature

This paper studied the effect of inclusion factors on the fatigue life. of a P/M superalloy. Tests were conducted at 600 °C and fractographies were examined to identify the failure source. The degree of the detrimental effect on life was related to inclusion size, position and applied stress level. An explanation for these factors on fatigue life based on fracture mechanics was proposed. Inclusions were considered as crack and K_max calculation was correlated with inclusion position and shape. The small crack growth behaviour was also considered and good life prediction was obtained by integrating the rate equation with initial defect size.