Thermo-mechanical fatigue behaviour of a duplex stainless steel

In this paper the thermo-mechanical fatigue (TMF) behaviour of the duplex stainless steel X2CrNiMoN22-5-3 is presented. TMF tests were carried out in the temperature range 100–350 °C on the duplex steel and on single-phase ferritic and austenitic steels comparable to the two phases of the duplex steel. The cyclic stress response curves of the duplex steel are showing pronounced primary and secondary hardening, where the former is in agreement with the cyclic hardening regime of the single-phase austenitic steel and the latter with that of the ferritic steel. For reference, additional isothermal low cycle fatigue (LCF) tests were performed at two strain rates at minimum and maximum temperature of the TMF temperature range, proving dynamic strain ageing effects occurring at 350 °C.