Fatigue performance of low temperature nitrided AISI 321 grade austenitic stainless steel

This study aims to present the effect of low temperature nitriding on the fatigue behavior of a titanium stabilized AISI 321 grade austenitic stainless steel. Upon nitriding at 420 °C in a fluidized bed reactor, the surfaces of the samples were covered with hybrid expanded austenite layer composed of nitrogen and carbon enriched zones. This surface layer combined the superior hardness (>1500 HV) and compressive residual stress (−6.8 GPa) without sacrificing the ductility to enhance the fatigue limit of the AISI 321 grade austenitic stainless steel about 15% in comparison to as-received state.