Analytical Evaluation of Weld Residual Stress Distribution for BWR Pipings

2008 ◽  
Author(s):  
M. Ando ◽  
K. Nakata ◽  
R. Sumiya ◽  
M. Itow ◽  
N. Tanaka
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Stainless Steel ◽  
Material Properties ◽  
Fem Analysis ◽  
Residual Stress Distribution ◽  
Temperature History ◽  
Stress Distributions ◽  
Weld Residual Stress ◽  
Stress Analyses

SCC (stress corrosion cracking) of low-carbon stainless steel piping has been found in Japanese BWR plants since 2002. According to JSME Fitness-for-Service Code, flaw evaluations are required to verify the life-time of piping if SCC is detected. In order to evaluate the SCC propagation behavior, it is necessary to obtain the residual stress distribution through the thickness of piping. In this study, the mock-up PLR (Primary Loop Recirculation system) piping weld joints made of L-grade Type 316 stainless steel with 300 mm and 600 mm diameter were fabricated and residual stress analyses were performed in order to obtain stress distributions. Material properties (specific heat, thermal conductivity, Young’s modulus, stress-strain curve, etc.) were obtained and temperature history during welding and weld residual stress were measured using these mock-ups. Material properties were used in the heat transfer and stress analyses. Measured temperature history and residual stress were compared with the results of heat transfer and stress analyses, respectively. Residual stress analysis of the pipe weld joint is commonly performed using axisymmetric element. In some cases of the combination of pipe diameter and thickness, residual stress obtained by the conventional method might differ from the experimental result owing to the difference of heating and constraint conditions between the axisymmetric model and the actual condition. In order to obtain more precise results, heat transfer and stress analyses were performed, taking into account the adjustment of the boundary condition in the weld passes of the last layer and the constraint condition using a spring element, respectively. On the outer and inner surfaces, almost the same residual stress distributions were obtained for the FEM analysis and the measurement. The residual stress distributions for PLR piping with different diameters, thicknesses, welding processes and groove angles were obtained by FEM analysis. Based on the results of the analyses, the influences of these parameters on residual stress were evaluated.

Study on Residual Stress Distribution in Surface Grinding

2011 ◽  
Vol 487 ◽  
pp. 49-53 ◽  
Author(s):  
Gui Cheng Wang ◽  
Chong Lue Hua ◽  
Ju Dong Liu ◽  
Hong Jie Pei ◽  
Gang Liu
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Phase Transformation ◽  
Material Properties ◽  
Residual Stress Distribution ◽  
Wheel Speed ◽  
Temperature History ◽  
Good Precision ◽  
Surface Residual Stress ◽  
Key Factor

The grinding process is currently used for most of the parts requiring good precision. However, the apparition of some damage related to this process is still uncontrolled. The major deterioration is from residual stress. In order to investigate the residual stresses caused by mechanical plastic deformation, thermal plastic deformation and phase transformation in ground components, a feasible numerical method was developed to accommodate appropriately thermal stress and phase transformation in a workpiece experiencing critical temperature variation during grinding. The change of the material properties was modeled as function of temperature history. The wheel velocityVsis a key factor in determining the distribution of residual stress; both the surface residual stress and the depth of residual stress are induced with the increase of the wheel speed.

Thermoelastoplastic Analysis of a Stainless Steel Plate Considering Phase Transformations

1993 ◽  
Vol 46 (11S) ◽  
pp. S12-S20 ◽  
Author(s):  
T. R. Tauchert ◽  
G. A. Webster ◽  
R. C. Reed
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Approximate Solution ◽  
Phase Transformations ◽  
Material Properties ◽  
Steel Plate ◽  
Phase Changes ◽  
Iterative Approach ◽  
Stress Distributions ◽  
Stainless Steel Plate

A quasistatic thermoelastoplastic analysis is given for the response of a traction-free plate subject to surface heating. The formulation incorporates temperature-induced phase changes which model experimentally obtained data for X22 CrMoV 12 1 stainless steel. The plate is discretized into layers, with material properties considered homogeneous within each layer. An incremental, iterative approach based upon Kirchhoff bending theory is employed to obtain an approximate solution to the problem. Numerical results illustrate the effects of phase transformations and temperature sensitivity of the material properties upon the transient and residual stress distributions.

Residual Stress Evaluation of Ni Based Weld Metal Using Neutron Diffraction Method

2006 ◽  
Vol 524-525 ◽  
pp. 697-702 ◽  
Author(s):  
Shinobu Okido ◽  
Hiroshi Suzuki ◽  
K. Saito
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Neutron Diffraction ◽  
Weld Metal ◽  
Diffraction Method ◽  
Fem Analysis ◽  
Butt Weld ◽  
Stress Evaluation ◽  
Neutron Diffraction Method

Residual stress generated in Type-316 austenitic stainless steel butt-weld jointed by Inconel-182 was measured using a neutron diffraction method and compared with values calculated using FEM analysis. The measured values of Type-316 austenitic stainless steel as base material agreed well with the calculated ones. The diffraction had high intensity and a sharp profile in the base metal. However, it was difficult to measure the residual stress at the weld metal due to very weak diffraction intensities. This phenomenon was caused by the texture in the weld material generated during the weld procedure. As a result, this texture induced an inaccurate evaluation of the residual stress. Procedures for residual stress evaluation to solve this textured material problem are discussed in this paper. As a method for stress evaluation, the measured strains obtained from a different diffraction plane with strong intensity were modified with the ratio of the individual elastic constant. The values of residual stress obtained using this method were almost the same as those of the standard method using Hooke’s law. Also, these residual stress values agreed roughly with those from the FEM analysis. This evaluation method is effective for measured samples with a strong texture like Ni-based weld metal.

On the Mechanics of Residual Stresses in Girth Welds

2006 ◽  
Vol 129 (3) ◽  
pp. 345-354 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Relative Importance ◽  
Stress Distributions ◽  
Unified Framework ◽  
Joint Geometry ◽  
Weld Residual Stress ◽  
Girth Welds ◽  
Welding Procedure

In this paper, some of the important controlling parameters governing weld residual stress distributions are presented for girth welds in pipe and vessel components, based on a large number of residual stress solutions available to date. The focus is placed upon the understanding of some of the overall characteristics in through-wall residual stress distributions and their generalization for vessel and pipe girth welds. In doing so, a unified framework for prescribing residual stress distributions is outlined for fitness-for-service assessment of vessel and pipe girth welds. The effects of various joint geometry and welding procedure parameters on through thickness residual stress distributions are also demonstrated in the order of their relative importance.

scholarly journals Probability Study on the Thermal Stress Distribution in Thick HK40 Stainless Steel Pipe Using Finite Element Method

Designs ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 9
Author(s):  
Sujith Bobba ◽  
Shaik Abrar ◽  
Shaik Mujeebur Rehman
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
High Temperature ◽  
Material Properties ◽  
Thermal Stresses ◽  
Steel Pipe ◽  
Stress Distributions ◽  
Stainless Steel Pipe ◽  
Deterministic Solution ◽  
Analytical Expressions

The present work deals with the development of a finite element methodology for obtaining the stress distributions in thick cylindrical HK40 stainless steel pipe that carries high-temperature fluids. The material properties and loading were assumed to be random variables. Thermal stresses that are generated along radial, axial, and tangential directions are generally computed using very complex analytical expressions. To circumvent such an issue, probability theory and mathematical statistics have been applied to many engineering problems, which allows determination of the safety both quantitatively and objectively based on the concepts of reliability. Monte Carlo simulation methodology is used to study the probabilistic characteristics of thermal stresses, and was implemented to estimate the probabilistic distributions of stresses against the variations arising due to material properties and load. A 2-D probabilistic finite element code was developed in MATLAB, and the deterministic solution was compared with ABAQUS solutions. The values of stresses obtained from the variation of elastic modulus were found to be low compared to the case where the load alone was varying. The probability of failure of the pipe structure was predicted against the variations in internal pressure and thermal gradient. These finite element framework developments are useful for the life estimation of piping structures in high-temperature applications and for the subsequent quantification of the uncertainties in loading and material properties.

A Damage Assessment of Autofrettaged Tubes Exposed to Decompositions in an LDPE Facility

2015 ◽  
Author(s):  
Jeffrey D. Cochran ◽  
Trace P. Silfies ◽  
Jonathan D. Dobis
Keyword(s):  
Residual Stress ◽  
Damage Assessment ◽  
Damage Parameter ◽  
Residual Stress Distribution ◽  
Stress Distributions ◽  
Remaining Life ◽  
Decomposition Reactions ◽  
Three Samples ◽  
Inner Surface ◽  
Almost All

The manufacture of low density polyethylene (LDPE) by radical polymerization regularly subjects components to extreme pressures exceeding 20 ksi and, possibly, to runaway decomposition reactions with temperatures exceeding 1500 °F and pressures above 30 ksi. Components subject to such extreme conditions are often autofrettaged to induce a beneficial residual stress distribution that retards crack growth and extends fatigue life. Three samples of autofrettaged tubes extracted from these components are examined here. Only one of these samples is known to have been exposed to multiple decompositions while in service. Measurements of the remaining residual stress were taken for each of these tube samples, and a number of other metallurgical tests were performed. The results show that the tube experiencing decompositions lost almost all of the beneficial residual stress induced by autofrettage and actually has a large, detrimental tensile stress at the inner surface. Corresponding to this is a band of embrittled material with a significantly altered microstructure that was most likely caused by thermal excursions. The tubes that experienced no decompositions showed no such alterations, and their residual stress distributions were relatively intact. An FFS assessment of crack-like flaws was performed on these tubes in accordance with API 579-1/ASME FFS-1 in order to determine the effect of this loss of residual stress on remaining life and quantify this loss in terms of a damage parameter.

Residual Stress Distribution of Non-Uniform Quenching in Al-Zn-Mg-Cu Aluminum Alloy Thick Plate

2020 ◽  
Vol 1003 ◽  
pp. 11-19
Author(s):  
Ya Nan Li ◽  
Yong An Zhang ◽  
Hong Lei Liu ◽  
Xin Yu Lv ◽  
Xi Wu Li ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Residual Stress ◽  
Aluminum Alloy ◽  
Heat Transfer Coefficient ◽  
Stress Distribution ◽  
Transfer Coefficient ◽  
Stress Level ◽  
Transverse Direction ◽  
Residual Stress Distribution ◽  
Surface Quenching

Effect of multi-section linear non-uniform heat transfer coefficient on quenching residual stress distribution in 27mm-thick Al-Zn-Mg-Cu aluminum alloy plate was simulation studied by using the finite element method, and the surface quenching residual stress distribution was measured by the X-ray diffraction method and hole-drilling method. The results show that the surface quenching residual stress represents the same distribution with non-uniform heat transfer coefficient in the transverse direction and the stress level maintains initial stress level of the heat transfer coefficient at each location. The distribution of the quenching residual stress in the center of the plate is approximately uniform and the stress level is approximately equal to average of maximum and minimum initial stress level. The measured surface quenching residual stress shows a wavy distribution in the transverse direction, which is similar to the simulated surface stress distribution without considering the stress level. The measurement results can be explained by the multi-section linear non-uniform quenching model.

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