Low Cycle Fatigue Behaviour of 316 LN Stainless Steel in Presence of Notch

In the present investigation, the low cycle fatigue behaviour of 316 LN stainless steel has been studied. The multiaxial state of stress has been introduced by incorporating a notch in the smooth specimens. In order to vary the state of stress in the specimens, notch radii of 5, 2.5 and 1.25 mm were incorporated. Low cycle fatigue tests have carried out on smooth and notched specimens of the steel at strain amplitudes ranging from +/- 0.25 to +/- 0.8 % at room temperature. Presence of a notch decreased the fatigue life appreciably. The fatigue life was found to decrease with increase in the strain amplitude for smooth and notched specimens and percentage decrease was higher for relatively sharper notches. The local strain at the notch root has been estimated by carrying out finite element analysis considering a material nonlinearity and using the combined kinematic and isotropic hardening model. The fatigue life of the notched specimens has been subsequently estimated using Coffin-Manson relationship relating the strain and fatigue life. The fatigue life for notched specimen has also been estimated by Neuber's rule. It is observed that Neuber's rule overestimated the fatigue life whereas finite element method estimated close to the experimental values.