Crack Growth Analysis of XH73M Nickel Alloy Under Fatigue, Creep-Fatigue Interaction and Thermo-Mechanical Conditions

Abstract

This study presents interpretation and evaluation of a range of isothermal and non-isothermal experimental crack growth data generated by four type tests carrying out by stress-controlled pure fatigue, creep-fatigue interaction, in-phase (IP) and out-of-phase (OOP) thermo-mechanical fatigue (TMF) conditions. A crack growth testing method has been developed utilizing inductive and convective heating and direct the crack tip opening displacement techniques for polycrystalline XH73M nickel-based alloy. The tests have been carried out using cycles with a trapezoidal and triangular waveform and a temperature range of 400–650°C. The crack growth experimental results interpretation is based on finite element analyses of the mechanical stress-strain rate fields at the crack tip. In order to determine the modified stress intensity factors under thermo-mechanical loading conditions multi-physics computations were carried out based on the coupled heat loss from magnetic field eddy currents and the forced convective air-cooling which provides the gradients of mechanical elastic–plastic deformations. As a result of the polycrystalline XH73M nickel-based alloy tests performed, it was found that from the crack growth acceleration point of view, the following order of arrangement of fatigue fracture diagrams is formed: isothermal creep-fatigue interaction, isothermal pure fatigue, non-isothermal in-phase thermo-mechanical fatigue and non-isothermal out-of-phase thermo-mechanical fatigue. It has been established that the greatest differences in the crack growth rate in the XH73M nickel alloy due to the type of mechanical loading (pure fatigue, fatigue-creep interaction, thermo-mechanical fatigue) occur at test temperatures above 400°C.