Recent exploration regarding advanced-ultra super critical (AUSC) plants suggest the usage of Ni–Cr–Co–Mo based super alloy 617M base for high-temperature components like steam piping and gas turbine rotor that undergoes repeated loads along the axial and radial direction at the time of operation for a prolonged time. The presence of pre-existing defects and flow-induced vibrations in the components under such condition needs proper examination for such crack nucleation and growth process, which requires detailed experimental studies related to fatigue crack growth rate (FCGR) behaviour at operating temperature (710 °C) using different load ratios (0.1, 0.2, 0.3, 0.4, 0.5 and 0.7). The results reveal that decreasing threshold stress intensity factor \(\left( {\Delta K_{{{\text{th}}}} } \right)\) with an increase in load ratio (R) and decaying at an average slope of  − 5.11 MPa m0.5. The influence of ‘R’ is also reflected on the major changes in Paris constant (C) and exponent (m). In addition, with the above influences on FCGR, observations are justified in acquaintance with a mechanistic overview and near-tip crack closure effect depending on investigated evidence both through the present study and existing literature survey.