Fatigue life prediction of GTA welded AISI 304L cruciform joints with lack of penetration using local-stress approach

The influence of welding procedure on fatigue properties of gas tungsten arc welded (GTAW) AISI 304L load carrying cruciform joints, containing lack of penetration (LOP) has been studied using a crack initiation-propagation (I-P) method. The crack process normally comprises two major phases: (1) the crack initiation life (N-I): and (2) the crack propagation life (N-p). 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 a 100 kN servo-hydraulic DARTEC universal testing machine with frequency of 30 Hz. Micro-measurements crack propagation gauges were used to find the crack initiation and propagation data during the fatigue process. The predicted lives were compared with the experimental values. It was found that the fatigue crack initiation lives of the joints fabricated by a double pass technique were relatively higher than the joints fabricated by a single pass technique. Test results were compared with BS 5400: part 10 (now replaced by BS 7608) design curve. (C) 2002 Elsevier Science Ltd. All rights reserved.