Numerical Evaluation of Temperature Field and Residual Stresses in an API 5L X80 Steel Welded Joint Using the Finite Element Method

Abstract

Metallic materials undergo many metallurgical changes when subjected to welding thermal cycles, and these changes have a considerable influence on the thermo-mechanical properties of welded structures. One method for evaluating the welding thermal cycle variables, while still in the project phase, would be simulation using computational methods. This paper presents an evaluation of the temperature field and residual stresses in a multipass weld of API 5L X80 steel, which is extensively used in oil and gas industry, using the Finite Element Method (FEM). In the simulation, the following complex phenomena were considered: the variation in physical and mechanical properties of the material as a function of the temperature, welding speed and convection and radiation mechanisms. Additionally, in order to characterize a multipass weld using the Gas Tungsten Arc Welding process for the root pass and the Shielded Metal Arc Welding process for the filling passes, the analytical heat source proposed by Goldak and Chakravarti was used. In addition, we were able to analyze the influence of the mesh refinement in the simulation results. The findings indicated a significant variation of about 50% in the peak temperature values. Furthermore, changes were observed in terms of the level and profile of the welded joint residual stresses when more than one welding pass was considered.

Residual Stresses with Time-Independent Cyclic Plasticity in Finite Element Analysis of Welded Joints

“…These six key points of the FE model provided the values of the longitudinal and transversal stresses (σ x and σ y ) and the values that correspond to the principal stresses (σ I and σ II ) of the welded joint. Similarly, Figure 8b shows typical values of the longitudinal and transversal stresses (σ x and σ y ) on the surface of the welded joint for any butt with a single V-groove that appears in the literature [4,70]. Also, Figure 8a shows the values of Von Mises residual stresses that were obtained from the FE model with reduced mesh for the first of the specimens welded after 100 s of simulation.…”

“…This is due to increased supply of heat by the GMAW welding torch [71]. Also, Figure 9 shows a comparison of the longitudinal (Figure 9a) and transversal (Figure 9b) residual stresses that were obtained by the three proposed FE models (results of strain gauge rosette 1 shown in Table 4) and the theoretical model proposed in the literature [4,70]. A certain similarity between the sign, the relative values, as well as the general shape of the longitudinal and transverse stresses obtained from the proposed FE models and those values shown in the literature, can be seen.…”

“…It can be seen in all tables that the maximum values of the principal stresses σ I and σ II that were obtained from the FE models and the experiments with the three specimens studied correspond to a depth of 0.127 mm. This corresponds practically to the stresses obtained on the surface of the welded joint (according to the literature [4,70]). Also, the tables show the MAE of the different rosettes that were studied.…”

Welding Distortion Prediction in 5A06 Aluminum Alloy Complex Structure via Inherent Strain Method

“…Many investigators have developed the analytical and experimental methods to predict the welding residual stresses. Da Nóbrega et al evaluated the temperature field and residual stresses in a multi-pass weld of API 5L X80 steel using the finite element method [9]. Zeng et al predicted the thermal elasto-plastic analysis using finite element techniques to analyze the thermo-mechanical behavior and evaluate the residual stresses and distortion of 5A06 aluminum alloy structure in discontinuous welding [10].…”

Improvement in the Design of Welded Joints of EN 235JR Low Carbon Steel by Multiple Response Surface Methodology

“…Tensile residual stresses are induced by shrinkage of the molten region, and compression residual stresses are induced by the effect of phase transformations [5]. The maximum values of residual stresses usually appear in the heat-affected zone (HAZ) on the toe of the weld cord and should be reduced as much as possible [6]. Variations in the residual stresses among the base metal, weld cord and HAZ can cause an increase in corrosion, as well as the formation of an irregular surface of the welded joints [7].…”