An Efficient Method for Estimation of Reduction of Welding Residual Stresses from Stress-Relief Annealing (Report III) : Development of Estimation Equations for Multi-Axial Stress State in Thick Welded Joint(Mechanics, Strength & Structural Design)

Stress-relief annealing (SR treatment) is included in the fabrication process of welded structures such as pressure vessels. This study aims to develop a simple analytical method which facilitates the calculation of transient and residual stresses during SR treatment, in order to easily determine the reasonable conditions of SR treatment for the recent large-size structures of high quality thick plates. In the first report, estimation equations for uni-axial stress states were formulated for relaxation tests at changing and constant temperatures. In the second report, the stresses relaxed by SR treatment in the thick welded joint were analyzed accurately by the finite element method based on thermal elastic-plastic creep theory. The characteristics of the changes of the welding residual stresses in multi-axial stress states were studied in detail. In this report, estimation equations in multi-axial stress states are developed for thick welded joints, based on the above characteristics.