Thermal fields and residual stresses analysis in TIG weldments of SS 316 and Monel 400 by numerical simulation and experimentation

Recent discoveries of stress corrosion cracking (SCC) at nickel-based metals in pressurized water reactors (PWRs) and boiling water reactors (BWRs) have raised concerns about safety and integrity of plant components. It has been recognized that welding residual stress is an important factor causing the issue of SCC in a weldment. In this study, both numerical simulation technology and experimental method were employed to investigate the characteristics of welding residual stress distribution in several typical welded joints, which are used in nuclear power plants. These joints include a thick plate butt-welded Alloy 600 joint, a dissimilar metal J-groove set-in joint and a dissimilar metal girth-butt joint. First of all, numerical simulation technology was used to predict welding residual stresses in these three joints, and the influence of heat source model on welding residual stress was examined. Meanwhile, the influence of other thermal processes such as cladding, buttering and heat treatment on the final residual stresses in the dissimilar metal girth-butt joint was also clarified. Secondly, we also measured the residual stresses in three corresponding mock-ups. Finally, the comparisons of the simulation results and the measured data have shed light on how to effectively simulate welding residual stress in these typical joints.

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The Compliance Method for Measurement of Near Surface Residual Stresses—Analytical Background

Journal of Engineering Materials and Technology ◽

10.1115/1.2904327 ◽

1994 ◽

Vol 116 (4) ◽

pp. 550-555 ◽

Cited By ~ 20

Author(s):

M. Gremaud ◽

W. Cheng ◽

I. Finnie ◽

M. B. Prime

Keyword(s):

Numerical Simulation ◽

Residual Stresses ◽

Random Errors ◽

Residual Stress Field ◽

Near Surface ◽

Surface Residual Stresses ◽

Zero Shift ◽

Stress States ◽

The Stability ◽

Piecewise Functions

Introducing a thin cut from the surface of a part containing residual stresses produces a change in strain on the surface. When the strains are measured as a function of the depth of the cut, residual stresses near the surface can be estimated using the compliance method. In previous work, the unknown residual stress field was represented by a series of continuous polynomials. The present paper shows that for stress states with steep gradients, superior predictions are obtained by using “overlapping piecewise functions” to represent the stresses. The stability of the method under the influence of random errors and a zero shift is demonstrated by numerical simulation.

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Influence of Forming Residual Stresses on the Welding Distortions of Two Thick Plates

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.83-86.125 ◽

2009 ◽

Vol 83-86 ◽

pp. 125-132 ◽

Cited By ~ 1

Author(s):

Sebastien Gallée ◽

Antoine Martin ◽

Vincent Robin ◽

Daniel Nelias

Keyword(s):

Numerical Simulation ◽

Electron Beam ◽

Heat Source ◽

Residual Stresses ◽

Electron Beam Welding ◽

Initial Conditions ◽

Rolling Process ◽

Vacuum Vessel ◽

Thick Plates ◽

Simulation Results

The manufacturing of the ITER (International Thermonuclear Experimental Reactor) vacuum vessel involves the welding of thick deformed plates. The aim of this study is to investigate the influence of forming residual stresses on the welding distortions of two thick plates. The plates are deformed using a three point rolling process. A first numerical simulation is performed to investigate the residual stresses induced by this process. The forming residual stresses are taken into account as initial conditions to perform the electron beam welding simulation of a deformed plate. This simulation first requires calibrating the heat source. Two welding simulations are then performed: the first one with residual stresses and the second one without. The comparison of the simulation results points out a low effect of the residual stresses on the electron beam welding distortions. As a result, in the next electron beam welding simulations of the vacuum vessel, no forming residual stresses will be taken into account.

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Implementation of Surface Radiation and Fluid-Structure Thermal Coupling in Atmospheric Reentry

International Journal of Aerospace Engineering ◽

10.1155/2012/402653 ◽

2012 ◽

Vol 2012 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Ojas Joshi ◽

Pénélope Leyland

Keyword(s):

Numerical Simulation ◽

Radiative Heating ◽

Surface Radiation ◽

Radiative Cooling ◽

Thermal Coupling ◽

Total Heat Flux ◽

Hollow Cone ◽

Atmospheric Reentry ◽

Thermal Fields ◽

Flap Region

During atmospheric reentry, radiative heating is one of the most important component of the total heat flux. In this paper, we investigate how the thermal radiation coming from the postshock region interacts with the spacecraft structure. A model that takes into account the radiation reflected by the surface is developed and implemented in a solid solver. A partitioned algorithm performs the coupling between the fluid and the solid thermal fields. Numerical simulation of a hollow cone head and a deployed flap region shows the effects of the radiative cooling and the significance of the surface radiation.

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