Welding-induced stresses and distortion in high-strength steel T-joints: Numerical and experimental study

Mehran Ghafouri,Antti Ahola,Joseph Ahn,Timo Björk

doi:10.1016/j.jcsr.2021.107088

Abstract

The main objective of this study is to develop a computational approach based on the finite element (FE) method to efficiently predict welding deformations and residual stresses of fillet welded T-joints made of high strength steel (HSS), S700, using different welding sequences and external constraints. With this aim, thermo-elastic-plastic FE models were developed in ABAQUS FE code based on Goldak's double ellipsoidal heat source model, material non-linearity and geometrical non-linearity. The results of the FE models in terms of temperature fields, angular distortion and transverse residual stress were verified against measurements. The results showed that angular distortion and transverse residual stress were significantly impacted by configuration of the external constraints, while longitudinal stress were less affected. It was found that the welding sequences had a smaller effect on the sequential and cumulative welding distortions and final residual stresses than the configuration of the external constraints. The results of this study are meaningful for understanding of the calibration and accuracy of FE computational approaches to simulate welding processes. Additionally, from a practical point of view, the results are important to understand the distortions and residual stress control measures of structural members made from HSSs.

Highlights

Gas metal arc welding (GMAW) is widely used to make permanent joints between mechanical components and structural members, pri marily due to its flexibility, practicality and high productivity [1]
Localized and rapid heating due to heat input from the welding torch to the base material followed by non-uniform cooling in the weld zone give rise to residual stresses and distortions in the weld
Welding-induced distortion, another un wanted side-effect frequently found in GMAW welds, can cause unde sirable secondary bending stresses, and it often results in loss of dimensional accuracy, which leads to extra costs for additional correc tion can cause schedule delays

Summary

Introduction

Gas metal arc welding (GMAW) is widely used to make permanent joints between mechanical components and structural members, pri marily due to its flexibility, practicality and high productivity [1]. The for mation of residual stresses and deformations, which is a significant problem in welded structures, is affected by a number of factors, which fall mainly into three categories. The third category encompasses processrelated factors including the welding method, welding sequences, heat input and mechanical boundary conditions [2]. Tensile residual stresses in the fusion zone (FZ) and heat-affected zone (HAZ) are known to contribute to acceleration of a wide range of degradation phenomena in components and structures [3]. Welding distortions can degrade joint quality, seriously impair fabrication and assembly of structural mem bers, and, in extreme cases, might lead to the joint or component being unusable

Objectives

Methods

Results