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.

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.

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.

An Experimental and Numerical Methodology to Investigate Crack Growth in a 304L Austenitic Stainless Steel Pipe Under Thermal Fatigue

2010 ◽  
Author(s):  
Pauline Bouin ◽  
Antoine Fissolo ◽  
Ce´dric Gourdin
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Crack Growth ◽  
Thermal Fatigue ◽  
Thermal Loading ◽  
Steel Pipe ◽  
Design Stage ◽  
Inner Surface ◽  
Stainless Steel Pipe

This paper covers work carried out by the French Atomic Energy Commission (CEA) to investigate on mechanisms leading to cracking of piping as a result of thermal loading existing in flow mixing zones. The main purpose of this work is to analyse, with a new experiment and its numerical interpretation, and to understand the mechanism of propagation of cracks in such components. To address this issue, a new specimen has been developed on the basis of the Fat3D experiment. This thermal fatigue test consists in heating a 304L steel pre-cracked tube while cyclically injecting ambient water onto its inner surface. The tube is regularly removed from the furnace for a crack characterisation. Finally, the crack growth is evaluated from the crack length differences between two stops. In parallel, a finite element analysis is developed using the finite element Cast3M code. A pipe with a semi-elliptical crack on its inner surface is modelled. A cyclic thermal loading is imposed on the tube. This loading is in agreement with experimental data. The crack propagates through the thickness. A prediction of the velocity of the crack is finally assessed using a Paris’ law type criteria. Finally, this combined experimental and numerical work on 304L austenitic stainless steel pipes will enable to improve existing methods to accurately predict the crack growth under cyclic thermal loadings in austenitic stainless steel pipe at the design stage.

Numerical Simulation of Residual Stress in Multi-Pass Butt-Welded Stainless Steel Pipe

2009 ◽  
Author(s):  
S. Kasa ◽  
M. Mouri ◽  
M. Tsunori ◽  
D. Takakura
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Three Dimensional ◽  
Structural Response ◽  
Welding Residual Stress ◽  
Steel Pipe ◽  
Inelastic Behavior ◽  
Axisymmetric Model ◽  
Stiffness Method ◽  
Stainless Steel Pipe

It is necessary to obtain an accurate welding residual stress distribution for the evaluation of stress corrosion cracking (SCC) behavior. However, a welding residual stress simulation for pipes is often performed by a two dimensional axisymmetric model because this type of simulation requires significant time to analyze the complicated inelastic behavior. This approximation deteriorates the modeling accuracy since the welding heat input and the structural response are approximated by axisymmetric responses although they are originally three dimensional. The authors propose “a virtual additional stiffness method” in order to improve the accuracy of the axisymmetric model. With this method, the difference between the axisymmetric model and a three dimensional behavior was greatly reduced. The virtual additional stiffness method was used to reproduce three dimensional constraints that were not taken into account in the axisymmetric model. In the case of the axisymmetric model, an unrealistic large thermal expansion was observed because of simultaneous heating along a hoop direction of the whole pipe. In order to compensate this unrealistic deformation, a virtual additional stiffness was added in axial and radial directions on the axisymmetric model. This stiffness was added by using spring elements whose positions and spring constants were determined by comparing the two and three dimensional models. Results obtained by this new method in the multi-pass butt-welded stainless steel pipe were in very good agreement with measurements of the mock-up specimens.

scholarly journals Ultrasonic inspection of a welded stainless steel pipe to evaluate residual stresses through thickness

2013 ◽  
Vol 49 ◽  
pp. 591-601 ◽  
Author(s):  
Yashar Javadi ◽  
Hamed Salimi Pirzaman ◽  
Mohammadreza Hadizadeh Raeisi ◽  
Mehdi Ahmadi Najafabadi
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Ultrasonic Inspection ◽  
Steel Pipe ◽  
Stainless Steel Pipe

Effects of Pipe Dimensions and Outer Surface-Buttering Weld Conditions on Residual Stress Distributions

2008 ◽  
Author(s):  
Nobuyoshi Yanagida
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Hoop Stress ◽  
Axial Stress ◽  
Butt Joint ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Butt Joints ◽  
Inner Surface

Effects of pipe dimensions and outer surface-buttering weld conditions on residual stress distributions were evaluated using the finite element method. Residual stresses were analyzed for 508–mm-diameter (500A) pipe 38.1 mm thick, 508–mm-diameter (500A) pipe 15.1 mm thick, and 267–mm-diameter (250A) pipe 15.1 mm thick. After the residual stresses at pipe butt joints were analyzed, residual stresses at these joints subjected to the outer surface-buttering welds were analyzed. Residual stresses were determined for various weld widths, thicknesses, and heat inputs. These analyses indicate that tensile axial stress occurred at inner surface of the pipe butt joint and that it decreased with increasing the outer surface buttering-weld width or heat input. They also indicate that compressive hoop stress occurred at inner surface of the joint and that outer surface-buttering weld increased it. The outer surface-buttering weld conditions that generate compressive residual stress at the inner surface of the pipe butt joints were determined.

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