Three-Dimensional Finite Element Analysis of Temperatures and Stresses in a Single-Pass Butt-Welded Pipe

Temperatures, stresses, and deformations in a single-pass butt-welded pipe are studied with a full three-dimensional finite element model. The model covers the whole circumference and the complete welding sequence; i.e., no assumption of axi-symmetry is made. The pipe studied has an outer diameter of 114.3 mm and a wall thickness of 8.8 mm. The material is carbon-manganese steel. The MIG-welding simulated results in a very high cooling rate. Low-temperature solid-state phase transformations, therefore, become significant and of importance to the residual stress field. The material model in the FE-code used (ADINA) is extended for that purpose. Notable calculated results are the residual compressive hoop stresses in the weld and the residual circumferential stress variations, especially in the beginning and end regions of the weld.