Temperature Dependence of Crack Growth Under LCF for Different Alloys

Fatigue crack growth in plastic regions is one of the main factors for life assessment of components subjected to plastic strains. Residual life can be evaluated considering a crack growing from component first load cycle, considering an appropriate crack growth model. The aim of this work is to discuss the effects of temperature on crack propagation during low cycle fatigue. In particular, a series of experiments at high temperature (up to T = 700°C) were performed on a Ni-based superalloy, to determine crack growth rates in the LCF regime. During tests interruptions, crack growth was measured using the plastic replica technique. Experimental results were examined in terms of crack growth rates and a model based on elastic-plastic J-Integral. Results showed that at high temperature there is a significant increase of crack growth rates respect to models usually valid at room temperature.