Numerical Analysis of Welding Residual Stress and Its Verification Using Neutron Diffraction Measurement

1999 ◽  
Vol 122 (1) ◽  
pp. 98-103 ◽  
Author(s):  
Masahito Mochizuki ◽  
Makoto Hayashi ◽  
Toshio Hattori
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Surface Stress ◽  
Welded Joint ◽  
Strain Analysis ◽  
Evaluation Methods ◽  
Welding Residual Stress ◽  
Diffraction Measurement ◽  
Stress Distributions ◽  
Inherent Strain

Direct measurements and computed distributions of through-thickness residual stress in a pipe butt-welded joint and a pipe socket-welded joint are compared. The analytical evaluation methods used were inherent strain analysis and thermal elastic-plastic analysis. The experimental methods were neutron diffraction for the internal residual stress, and X-ray diffraction and strain-gauge measurement for the surface stress. The residual stress distributions determined using these methods agreed well with each other, both for internal stress and surface stress. The characteristics of the evaluation methods and the suitability of these methods for each particular welded object to be evaluated are discussed. [S0094-4289(00)01501-2]

Measurement of Through-Thickness Residual Stress in Primary Piping of Girth Welded Joint

2008 ◽  
Vol 580-582 ◽  
pp. 577-580
Author(s):  
Masahito Mochizuki ◽  
Shigetaka Okano ◽  
Gyu Baek An ◽  
Masao Toyoda
Keyword(s):  
Residual Stress ◽  
Direct Measurement ◽  
Welded Joint ◽  
Strain Analysis ◽  
Residual Stress Distribution ◽  
Welding Residual Stress ◽  
Thickness Direction ◽  
Welded Pipe ◽  
Inherent Strain ◽  
Pipe Joint

The welding residual stress of a butt-welded pipe joint is evaluated, using inherent strain analysis. The residual stress distribution is obtained in detail along the thickness direction. The residual stresses are similar to values obtained by direct measurement on the specimen surface; as if though direct measurement is not used for the inherent strain analysis. These results indicate that inherent strain analysis is effective in evaluating through-thickness residual stress in primary piping of girth welded joint.

Inherent-Strain-Based Theory of Measurement of Three-Dimensional Residual Stress Distribution and Its Application to a Welded Joint in a Reactor Vessel

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Keiji Nakacho ◽  
Naoki Ogawa ◽  
Takahiro Ohta ◽  
Michisuke Nayama
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Strain Distribution ◽  
Measurement Method ◽  
Welded Joint ◽  
Three Dimensional ◽  
Reactor Vessel ◽  
Residual Stress Distribution ◽  
Stress Distributions ◽  
Inherent Strain

The stress that exists in a body under no external force is called the inherent stress. The strain that is the cause (source) of this stress is called the inherent strain. This study proposes a general theory of an inherent-strain-based measurement method for the residual stress distributions in arbitrary three-dimensional bodies and applies the method to measure the welding residual stress distribution of a welded joint in a reactor vessel. The inherent-strain-based method is based on the inherent strain and the finite element method. It uses part of the released strains and solves an inverse problem by a least squares method. Thus, the method gives the most probable value and deviation of the residual stress. First, the basic theory is explained in detail, and then a concrete measurement method for a welded joint in a reactor vessel is developed. In the method, the inherent strains are unknowns. In this study, the inherent strain distribution was expressed with an appropriate function, significantly decreasing the number of unknowns. Five types of inherent strain distribution functions were applied to estimate the residual stress distribution of the joint. The applicability of each function was evaluated. The accuracy and reliability of the analyzed results were assessed in terms of the residuals, the unbiased estimate of the error variance, and the welding mechanics. The most suitable function, which yields the most reliable result, was identified. The most reliable residual stress distributions of the joint are shown, indicating the characteristics of distributions with especially large tensile stress that may produce a crack.

Residual Stress Analysis by Simplified Inherent Strain at Welded Pipe Junctures in a Pressure Vessel

1999 ◽  
Vol 121 (4) ◽  
pp. 353-357 ◽  
Author(s):  
M. Mochizuki ◽  
M. Hayashi ◽  
T. Hattori
Keyword(s):  
Residual Stress ◽  
Pressure Vessel ◽  
Welded Joint ◽  
Three Dimensional ◽  
Small Diameter ◽  
Welding Residual Stress ◽  
The Finite Element Method ◽  
Diameter Pipe ◽  
Welded Pipe ◽  
Inherent Strain

We present a new and simplified method of estimating residual stress in welded structures by using inherent strain. The method makes use of elastic analysis by means of the finite element method and is used to calculate the residual stress in complicated three-dimensional structures efficiently. The inherent strain distribution in a welded joint of a small-diameter pipe penetrating a pressure vessel was assumed to be a simple distribution, and the residual stress was calculated. Inherent strain distributions were inferred from those of welded joints with simple shapes. The estimated residual stress using these inferred inherent strains agrees well with the measurements of a mock-up specimen. The proposed method is a simple way to estimate welding residual stress in three-dimensional structures of complicated shapes.

Comparison of Neutron Diffraction Residual Stress Measurements of Steel Welded Repairs With Current Fitness-for-Purpose Assessments

2008 ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Trevor R. Finlayson ◽  
Ronald B. Rogge ◽  
Ronald L. Donaberger ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Thick Plate ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Stress Variation ◽  
Full Penetration ◽  
Heat Treated ◽  
Strain Stress ◽  
Neutron Diffraction Technique

In this research the neutron diffraction technique was used to investigate the residual stress distributions in carbon steel components with weld repairs. Two full penetration weld repairs were studied using a) the stringer bead and b) the temper bead weld techniques in 25 mm thick plate. The welds were not post weld heat treated. The focus of the measurements is on the values of the sub-surface and through-thickness strain/stress variation near the middle of the weld and the toe. The experimental results showed that both processes had high residual stresses particularly through the thickness. The measurements were compared with current fitness-for-purpose approaches, such as BS7910 and R6 showing that these approaches underestimated and overestimated the stresses in various regions.

scholarly journals Welding Residual Stress Distribution of Quenched and Tempered and Thermo-Mechanically Hot Rolled High Strength Steels

2014 ◽  
Vol 996 ◽  
pp. 457-462 ◽  
Author(s):  
Thomas Schaupp ◽  
Dirk Schröpfer ◽  
Arne Kromm ◽  
Thomas Kannengiesser
Keyword(s):  
Residual Stress ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Stress Evolution ◽  
Alloying Element ◽  
Steel Manufacturing ◽  
Advanced Technologies ◽  
Hot Rolled

Beside quenched and tempered (QT) high strength steels advanced technologies in steel manufacturing provide steels produced by the thermo-mechanical controlled process (TMCP) with yield strength of 960 MPa. These steels differ in the carbon and micro-alloying element content. With variation of heat control TIG-welded dummy seams on both steel types were performed. Analyses concerning microstructure and residual stress evolution due to welding showed typical stress distributions according to common concepts. Yet, the TMCP-steel shows higher residual stresses than the QT-steel.

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