Fatigue crack growth of heat-resistant austenitic cast iron under isothermal and thermomechanical fatigue conditions

Isothermal fatigue crack growth tests were performed at room temperature, 500 °C, and 700 °C, while thermomechanical fatigue (TMF)-crack growth tests with minimum and maximum temperatures of 400 °C and 700 °C, respectively, were conducted under various stress conditions on the heat-resistant austenitic cast iron EN–GJSA–XNiSiCr35–5–2 (commonly referred to as Ni–Resist D-5S). Both isothermal and TMF experiments revealed an increase in crack growth rate with rising force ratio R . In the TMF tests, in-phase loading resulted in a higher crack growth rate compared to out-of-phase loading. A comparative assessment of different in-situ crack length measurement techniques − including the potential drop method, compliance measurement, and thermography − was carried out. In addition, microstructural analyses of crack propagation mechanisms were performed concurrently with the experiments