Experimental study of type 316 stainless steel failure under LCF/TMF loading conditions

• Strain-controlled isothermal LCF tests were conducted at 500 and 650 °C.
• Fully reversed TMF tests were conducted at 500–650 °C at various strain ranges.
• Symmetrical hold time introduced to observe interaction of creep/fatigue damage.
• Microstructural investigations were conducted using scanning electron microscope.
• The evolution of energy was used to identify the number of cycles at various stages.

A detailed investigation of low cycle fatigue (LCF) and thermo-mechanical fatigue (TMF) of a 316FR type stainless steel is presented in this paper in order to identify the failure mechanism based on the experimental results and the subsequent metallography of the samples. The LCF–TMF servohydraulic testing with a temperature uniformity of less than ±5 °C within the gauge section of the specimens was employed to conduct the experimental tests. Fully-reversed, strain-controlled isothermal tests were conducted at 650 °C for the strain ranges of Δɛ = ±0.4%, ±0.8%, ±1.0% and ±1.2%. Strain-controlled in-phase (IP) thermo-mechanical fatigue tests were conducted on the same material and the temperature was cycled between 500 °C and 650 °C. Additionally, the creep–fatigue interactions were investigated with the introduction of symmetrical hold time under both LCF–TMF tests. The cyclic behaviour was further studied by performing microstructural investigations using the scanning electron microscope (SEM).