Effect of Strain Rate on the Low Cycle Fatigue Behavior of 316L(N) Stainless Steel Weld Joints

The aim of the present paper is to study the effect of strain rate on the low cycle fatigue (LCF) behavior of indigenously developed 316LN stainless steel weld joint (0.14 N wt. % base metal welded with 0.1 wt. % N electrodes). Fully reversed total axial strain-controlled LCF tests were conducted at 823 K using a servohydraulic machine, equipped with a resistance heating furnace. Tests were conducted in air at ±0.6% strain amplitude employing strain rates 3×10−3s−1, 3×10−4s−1 and 3×10−5s−1 to investigate the effect of strain rate in the dynamic strain aging regime (DSA). Initial brief hardening, negative strain rate stress response and lowering of fatigue life with decreasing strain rate have been correlated to DSA operating at 823 K. The LCF behaviour of weld joints are correlated to the microstructural changes during fatigue cycling in order to explain the underlying deformation mechanism and fracture behaviour.