Our new paper titled Correlation of the high and very high cycle fatigue response of ferrite based steels with strain rate-temperature conditions is published in Acta Materialia. Congratulations to Noushin Torabian, who will defend her PhD in two weeks, and co-authors for an interesting take on very high cycle fatigue behaviour of dual-phase steel. The paper is available online here.
The following map, taken from the paper, depicts the transition between athermal regime and thermally-activated regime for screw dislocations, which are indicated as Region I and Region II, respectively. The solid line representing the transition boundary between these two deformation regimes was obtained from the empirical equation proposed by Rosenfield and Hahn (Trans. Am. Soc. Mater, 1966) for low carbon steels. These different regimes will be attained depending on testing parameter and variable such as loading frequency and temperature, hence explaining the discrepancies (or the lack of) in the response of body-centered cubic Fe-based materials between conventional and ultrasonic fatigue testing.