Thermo-Mechanical Analysis of Residual Stresses in Arc Welded Thin-Walled Cylinders

Abstract

The problem of reduced strength of the structures in and around the weld zone due to the residual stresses in arc welding process is a major concern of the welding industry for decades. The prediction of the transient and residual stress fields during and after the completion of the welding process is of critical importance to ensure the structural integrity of welded structures. Circumferentially welded thin-walled cylinders are widely utilized in many engineering applications including the oil transportation system, boiler and pressure vessel industries. This paper presents a detailed three-dimensional finite element (FE) study to investigate the welding induced residual stresses in circumferentially welded thin-walled cylinders. The complex phenomenon of arc welding is numerically solved by sequentially coupled transient, non-linear thermo-mechanical analysis approach to simulate Gas Tungsten Arc (GTA) Welding process. Single pass butt-welded geometry with single “V” groove for two 300 mm outer diameter cylinders with 3 mm wall thickness and 150 mm length are used in numerical simulations. Temperature dependent thermo-mechanical behavior for low carbon steel is modeled and filler metal deposition by using the element birth and kill features is incorporated. Widely accepted double ellipsoidal GOLDAK heat source model for arc welding is introduced and implemented. Simulation of the entire welding process is accomplished by using author written subroutines in ANSYS®, general purpose FE software. The accuracy of the developed FE simulation strategy is validated with experimentation for temperature distribution and residual stresses.