Effects of strain rate and mean strain on cyclic behavior of aluminum alloys under isothermal and thermo-mechanical fatigue loadings

In this paper, effects of strain rate and mean strain on the cyclic behavior and the lifetime of aluminum–silicon alloys are investigated under thermo-mechanical and isothermal fatigue loadings. To achieve these goals, low cycle fatigue tests are accomplished at evaluated temperatures under various strain rates (by changing the loading frequency) and different strain ratios (minimum to maximum strain). Thermo-mechanical fatigue experiments are performed in an out-of-phase condition where the temperature varies between 50 and 250 °C. Various heating/cooling rates are taken into account to assess the strain rate effect and different starting temperatures are considered to study the mean strain effect.

► TMF/LCF behavior of aluminum alloys is studied for various strain rates and ratios. ► The strain ratio effect on HT-LCF of A357 is more significant than A356 alloy. ► Increasing the strain rate increases HT-LCF lifetime and softening in A357 alloy. ► No change can be observed in OP-TMF lifetime when the strain ratio increases. ► A lifetime prediction model is presented based on cumulative plastic strain energy.