Investigation of the Self-Heating of Q460 Butt Joints and an S-N Curve Modeling Method Based on Infrared Thermographic Data for High-Cycle Fatigue

In this study, we investigated the fatigue behavior of Q460 welded joints using tensile tests. Furthermore, real-time temperature profiles examined specimens were recorded by infrared thermography. Based on obtained thermographic data, calculated entropy production rate under different stress amplitudes. Hypothetically, during high-cycle (HCF) could be divided into two parts. The first is induced inelastic that corresponds to damage accumulation, and second originates from anelasticity associated with recoverable non-damaging microstructural motions. turning point levels represents an index for limit estimation. Then, considering average threshold exists HCF, related accumulation (cumulative entropy) testing three same amplitude above limit. Finally, a rapid three-parameter S-N curve survival probability 50% obtained. combined maximum likelihood method, 5% 95% curves are established. Most experimental data distributed in area between correspond rate, indicating good accordance test data.