High Cycle Fatigue Damage Mechanisms of MAR M 247 Superalloy at High Temperatures
High cycle fatigue tests of the MAR M 247 superalloy under constant load were conducted with the aim to determine S N curves at temperatures 650, 800, 900 and 950 degC. It has been found that the slope of the S N curves reflects changes of the cyclic deformation mechanism with temperature. At temperatures 650 and partly at 800 degC, fatigue crack propagation exhibits crystallographic character (propagation along the {111} system) in early stages of the fatigue life. The crystallographic mode of the fatigue crack propagation was found to disappear at temperatures 900 and 950 degC.
Transactions of the Indian Institute of Metals