Thermo mechanical fatigue behaviour of a duplex stainless steel in the range of 350–600 °C

• TMF tests and tensile tests on duplex steel in aged and annealed conditions.
• Temperature range from 350 °C to 600 °C with constant heating/cooling rate of 4 K/s.
• Curie temperature was determined and related to spinodal decomposition.
• Spinodal decomposition was found to be partly reversible by annealing at 600 °C.
• TMF behaviour in the range 350–600 °C is not affected by spinodal decomposition.

The thermo mechanical fatigue behaviour of a ferritic–austenitic duplex stainless steel has been investigated in a temperature range of 350–600 °C. The Curie temperature (TCURIE) was determined by an abrupt increase of the power of the inductive heating device and a small control deviation of the temperature. Thus, according to Tavares et al. [1] the evolution of the spinodal decomposition in the DSS was characterised by the shift of the Curie temperature for each test. The results are compared with ageing and annealing experiments in combination with tensile tests at room temperature. In addition, microstructure observations were performed in a field-emission scanning electron microscope.