Interaction between oxidation and thermo-mechanical fatigue in IN738LC superalloy — I

The present paper deals with the thermo-mechanical fatigue-oxidation interaction through a quantitative study of matrix oxidation in IN738LC, a conventionally cast high chromium low carbon nickel-base superalloy used for land based turbine blading. It is shown that the TMF cycling strongly influences the oxidation process in this superalloy. The study of oxidation under out-of-phase TMF loading in IN738LC has shown that: (1) the mechanical strain range influences the general matrix oxidation of the alloy; (2) the introduction of a hold time in TMF cycling considerably enhances the oxidation process; (3) increasing the amount of mechanical strain range under TMF loading accelerates the average oxidation and depleted zone growth rates according to a power law relationship; (4) the oxidation kinetics for the alloy under TMF condition seems to be linear, caused by oxide fracturing and/or spalling which results in a nonprotective accelerated oxidation process.