Fatigue life prediction of gas tungsten arc welded AISI 304L cruciform joints with different LOP sizes

Abstract Fatigue life evaluations have been carried out on gas tungsten arc welded (GTAW) load-carrying cruciform joints of AISI 304L stainless steel with lack of penetration (LOP) using conventional S-N and crack initiation-propagation (I-P) methods. The crack process normally comprises two major phases: (1) the crack initiation life (Ni): and (2) the crack propagation life (Np). The local stress-life approach is used to estimate the crack initiation life and a fracture mechanics approach for predicting crack propagation life of welded joints. Constant amplitude fatigue tests with stress ratio, R=0 were carried out using 100 KN servo-hydraulic DARTEC universal testing machine with frequency of 30 Hz. An automatic crack monitoring system based on crack propagation gauges was used to find the crack initiation and propagation data during fatigue process. The predicted lives were compared with the experimental values. It was found that the fatigue lives of the joints with LOP=2 mm for 6 mm thickness plate were relatively higher than those for the joints with other LOP sizes. Test results were compared with BS 5400: part 10 (now replaced by BS 7608) design curve.