Temperature-Dependent Bending Ratcheting Behavior of a 316LN Stainless Steel

Load-controlled cyclic three-point bending tests were conducted on a 316LN austenitic stainless steel at temperatures ranging from 20 to 450 °C. A fair method based on the concept of equivalent maximum nominal stress (MNS) was proposed to quantitatively characterize the temperature-dependent bending ratcheting behavior of the steel. The equivalent MNS was determined by ensuring consistent residual deflections after the first bending cycle at varied temperatures. Two loading paths, namely simple cycling and dwelling-cycling, were employed under the equivalent MNS. Under the simple cycling path, the ratcheting behavior of the steel tends to shakedown as temperature rises. Under the simple cycling path where a dwelling was introduced at the maximum loading, the ratcheting potential of the steel appears to be exhausted at relatively low temperatures. These facts are presumably attributed to the loss of viscosity induced by the dynamic strain aging effect.