Isothermal low-cycle fatigue and fatigue-creep of a 42CrMo4 steel

A series of strain-controlled experiments was performed on quenched and tempered martensitic steel 42CrMo4, with and without a tensile peak strain-dwell. The experiments were performed for three different strain rates and for two different strain dwells in the temperature range between 300 and 600 degrees C. Scanning electron microscopy and optical microscopy were then used to study the microstructure evolution and the damage mechanisms. The experimental results show that tensile peak strain-dwell may lead to interaction between creep and fatigue. Finally, the effect of a decreasing strain rate and increasing duration of the strain-dwell on the observed fatigue lifetime is quantified.