Evaluation by Two-Dimensional Finite Element Analysis of the Effect of Number of Weld Layers on the Residual Stress Profile in Stainless Steel Pipe Welds

2020 ◽  
Author(s):  
Alexandra K. Zumpetta ◽  
Andrew W. Stockdale ◽  
Trevor G. Hicks ◽  
William R. Mabe ◽  
Jessica L. Coughlin
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Weld Bead ◽  
Steel Pipe ◽  
Two Dimensional ◽  
Element Analysis ◽  
Stainless Steel Pipe ◽  
Stress Profiles

Abstract Tensile residual stresses associated with stainless steel pipe welds can promote in-service cracking and influence the need for inspections. Previous research via finite element analysis (FEA) [1] and experimental characterization [2] has shown that welds in thick wall pipe can produce compressive residual stresses at the inner diameter (ID) surface. However, research that has evaluated the relationship between the number of weld layers, stemming from different weld bead sizes, and the resulting pipe residual stress profiles is limited. This investigation used two-dimensional (2D) FEA to evaluate the influence of the number of weld layers (resulting from different weld bead sizes) on the ID surface and through-wall residual stress profiles for varying stainless steel pipe radii, thicknesses, and weld joint geometries. The findings herein are compared to previous experimental results [2]. The results demonstrated that for the larger pipe sizes and the welding conditions investigated, increasing the number of weld layers (reducing individual weld bead sizes) reduced the ID surface tensile axial residual stresses. In the larger pipe sizes, the magnitude of the tensile residual stresses extending through (into) the pipe wall is also reduced with an increased number of weld layers. The FEA results show that the weld joint geometry may not affect the residual stress profiles as strongly as do the number of weld layers, based on the similarities in the tensile stress values for the joint geometries that were evaluated.

Evaluation of Residual Stresses in Small Diameter Stainless Steel Pipe Welds by Two-Dimensional and Three-Dimensional Finite Element Analyses

2014 ◽  
Author(s):  
Francis H. Ku ◽  
Trevor G. Hicks ◽  
William R. Mabe ◽  
Jason R. Miller
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Three Dimensional ◽  
Steel Pipe ◽  
3D Analysis ◽  
Two Dimensional ◽  
Finite Element Analyses ◽  
Stainless Steel Pipe

Two-dimensional (2D) and three-dimensional (3D) weld-induced residual stress finite element analyses have been performed for 2-inch Schedule 80 Type-304 stainless steel pipe sections joined by a multi-layer segmented-bead pipe weld. The analyses investigate the similarities and differences between the two modeling approaches in terms of residual stresses and axial shrinkage induced by the pipe weld. The 2D analyses are of axisymmetric behavior and evaluate two different pipe end constraints, namely fixed-fixed and fixed-free, while the 3D analysis approximates the non-axisymmetric segmented welding expected in production, with fixed-free pipe end constraints. Based on the results presented, the following conclusions can be drawn. The welding temperature contour results between the 2D and 3D analyses are very similar. Only the 3D analysis is capable of simulating the non-axisymmetric behavior of the segmented welding technique. The 2D analyses yield similar hoop residual stresses to the 3D analysis, and closely capture the maximum and minimum ID surface hoop residual stresses from the 3D analysis. The primary difference in ID surface residual stresses between the 2D fixed-fixed and 2D fixed-free constraints cases is the higher tensile axial stresses in the pipe outside of the weld region. The 2D analyses under-predict the maximum axial residual stress compared to the 3D analysis. The 2D ID surface residual stress results tend to bound the averaged 3D results. 2D axisymmetric modeling tends to significantly under-predict weld shrinkage. Axial weld shrinkage from 3D modeling is of the same magnitude as values measured in the laboratory on a prototypic mockup.

The Measurement and Modelling of Residual Stresses in a Stainless Steel Pipe Girth Weld

2008 ◽  
Author(s):  
K. Ogawa ◽  
L. O. Chidwick ◽  
E. J. Kingston ◽  
R. Dennis ◽  
D. Bray ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Outer Surface ◽  
Mixed Mode ◽  
Steel Pipe ◽  
Outer Diameter ◽  
Hardening Model ◽  
Inner Surface ◽  
Stainless Steel Pipe

This paper presents results from a program of residual stress measurements and modelling carried out for a pipe girth weld of 369 mm outer diameter and 40 mm thickness. The component consisted of two 316 stainless steel pipe sections joined together using a “single-V” nickel base alloy (alloy 82) weld. The residual stresses were measured using the Deep-Hole Drilling (DHD) technique and modelled using ABAQUS. Biaxial, through-thickness residual stresses were measured through the weld centreline at a total of 6 different locations around the component. At three of the measurement locations the DHD process was carried out from the outer surface of the component with the remaining three, one of which coinciding with the weld start/stop position, carried out from the inner surface of the component. The differences in DHD process application (i.e. outer-to-inner or inner-to-outer) was carried out as a sub-objective to investigate the sequence of residual stress relaxation and its influence on the measured results. Good measurement repeatability was found between all locations. The hoop residual stresses were tensile at the outer surface, increasing to a maximum of 350 MPa at 10 mm depth, then decreasing to a minimum of −325 MPa at a depth of 34 mm, before increasing again towards the inner surface. The axial residual stresses were found to be similar in profile to the hoop residual stresses albeit lower in absolute magnitude by roughly 100 MPa. For this component it was found that the hoop residual stresses showed an influence of process direction, whereas for the axial residual stresses no influence was found. The modelling of the residual stresses generated was undertaken using a 2D axisymmetric finite element analysis containing 25 discrete weld beads. Each of the 25 weld beads were analysed sequentially using the following stages: heat source modelling, thermal analysis, elastic-plastic mechanical analysis. The sensitivity of the residual stresses generated with respect to the material hardening model used was investigated (i.e. kinematic, isotropic and mixed mode – kinematic/isotropic). Generally, the isotropic hardening model produces the highest predictions, the kinematic hardening model produces the lowest predictions with the mixed mode model lying in-between. Good agreement was found between the measured and modelled residual stresses. The main discrepancy existed in the hoop direction with the modelled residual stresses being the most tensile by roughly 200 MPa at depths within 15 mm of the outer surface of the pipe.

Finite Element Analysis of Residual Stresses in Butt Welding of Stainless Steel Plates by GTAW

2010 ◽  
Author(s):  
Gurinder Singh Brar ◽  
Rakesh Kumar
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stainless Steel ◽  
Residual Stresses ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Element Analysis ◽  
Aisi 304 ◽  
Butt Welding

Welding is one of the most commonly used permanent joining processes in the piping and pressure vessel industry. During welding a very complex thermal cycle is applied to the weldment, which in turn causes irreversible elastic-plastic deformation and consequently gives rise to the residual stresses in and around fusion zone and heat affected zone (HAZ). Presence of residual stresses may be beneficial or harmful for the structural components depending on the nature and magnitude of stresses. The beneficial effect of compressive stresses have been widely used in industry as these are believed to increase fatigue strength of the component and reduce stress corrosion cracking and brittle fracture. In large steel fabrication industries such as shipbuilding, marine structures, aero-space industry, high speed train guide ways and pressure vessels and piping in chemical and petrochemical industry the problem of residual stresses and overall distortion has been and continue to be a major issue. It is well established fact that material response of structural components is substantially affected by the residual stresses when subjected to thermal and structural loads. Due to these residual stresses produced in and around the weld zone the strength and life of the component is reduced. As AISI 304 stainless steel has excellent properties like better corrosion resistance, high ductility, excellent drawing, forming and spinning properties, so it is almost used in all types of application like chemical equipment, flatware utensils, coal hopper, kitchen sinks, marine equipment etc. But because of the problems of residual stresses during the time of welding it is very essential to understand the behavior and nature of AISI 304 stainless steel material. So in order to overcome all these problems a 3-dimensional finite element model is developed in a commercially available FEA code by drafting an approximate geometry of the butt welded joint and then the finite element analysis is performed, so that one can understand the complete nature of residual stresses in butt welding of AISI 304 stainless steel plate. In this paper, butt welding simulations were performed on two AISI 304 stainless steel plates by gas tungsten arc welding (GTAW). Analysis of butt welded joint by commercially available finite element analysis code showed that butt weld produced by GTAW resulted in 782.84 MPa of residual stress in plates. In addition, the residual stress is plotted against axial distance to have a clear picture of the magnitude of residual stress in and around weld area.

scholarly journals A Comparative Study on the Calculating of Thickness and Height at T-Shaped Branch for KS D 3595 Stainless Steel Pipe using the Results both the Finite Element Method and the Experiment

2020 ◽  
Vol 34 (5) ◽  
pp. 50-54
Author(s):  
Jun-Seok Nam ◽  
Hong-Sun Ryou
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Branch Pipe ◽  
Material Behavior ◽  
Steel Pipe ◽  
Minimum Thickness ◽  
Element Analysis ◽  
Main Pipe ◽  
Stainless Steel Pipe

Stainless steel pipe for general piping specified under the KS D 3595 standard is used as a substitute for carbon steel pipe in places where corrosion of coastal regions is a concern because there is little risk of corrosion. In order to install the branch pipe from the main pipe, the pipe is punched into the elliptical shape and the cone-shaped plug is pulled out of the main pipe to form a T-Shaped branch portion. However, there is a problem that is damaged when welding the pipe to the branch, but it is insufficient to understand the behavior of the material and the principle of damage due to plastic deformation when forming the branch. Hence, in this study, material behavior and stress were analyzed through finite element analysis. The diameter of the KS D 3595 stainless steel main was varied from 75 mm to 100 mm and the diameter of the branch pipe was varied from 25 mm to 80 mm. So, a total of eighteen cases were analyzed. The obtained results indicate that the maximum residual stress occurs in the central portion of the pipe along the longitudinal direction of the branch, and the residual stress increases as the size of the branch processing portion increases. Furthermore, in this study the minimum cutting height required for compatibility with the minimum thickness of the branching portion is reported.

Fast Three-Dimensional Finite Element Analysis of Weld Overlay Application on a Formed Feeder Elbow

2011 ◽  
Author(s):  
Francis H. Ku ◽  
Pete C. Riccardella
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fe Method ◽  
Element Analysis ◽  
Weld Overlay ◽  
Welding Processes

This paper presents a fast finite element analysis (FEA) model to efficiently predict the residual stresses in a feeder elbow in a CANDU nuclear reactor coolant system throughout the various stages of the manufacturing and welding processes, including elbow forming, Grayloc hub weld, and weld overlay application. The finite element (FE) method employs optimized FEA procedure along with three-dimensional (3-D) elastic-plastic technology and large deformation capability to predict the residual stresses due to the feeder forming and various welding processes. The results demonstrate that the fast FEA method captures the residual stress trends with acceptable accuracy and, hence, provides an efficient and practical tool for performing complicated parametric 3-D weld residual stress studies.

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