Numerical investigation of residual stresses in circumferential and longitudinal welded joints

Welded cylinder structures such as pressure vessels and pipes have found its application in power stations. They experience high temperature and pressure during the operation. As welding induces residual stresses, it is vital to study the stress distribution in predicting their service lives. In the present work, a sequentially coupled thermal structural analysis is carried to study the thermal field distribution and subsequent residual stresses during welding. Finite element (FE) model of gas tungsten arc welding (GTAW) process is developed to produce circumferential and longitudinal butt weld joints of AH 36 (low carbon steel) cylinder components. Welding of cylinders is analyzed by changing their outer diameters. Effect of cylinder outer diameter on residual stresses is studied. The weld induced hoop and axial stresses are evaluated on both inner surfaces (I/S) and an outer surface (O/S) of the cylinder. The magnitude of hoop and axial stresses in longitudinal butt weld joints are 45% and 95% higher than circumferential butt weld joints. By comparing the results, longitudinal butt weld joints are not desirable for fabricating cylinder components. The analysis model is validated with experimental measurements.