Dominating Driven Factors of Hydrogen Diffusion and Concentration for the Weld Joint–Coupled Analysis of Heat Transfer Induced Thermal Stress Driven Hydrogen Diffusion–

Hydrogen induced cracking occurs at the welded position of the structure due to concentration of hydrogen during cooling process of welding. A square groove weld joint is one of typical one in engineering field. Hydrogen embrittlement cracking is sometimes caused during cooling process of a weld joint. For such case, hydrogen diffusion and concentration behaviour is a significant factor. One of authors has been proposed α multiplication method which magnifies the hydrogen driving term in the diffusion equation to find out detailed behaviours of hydrogen concentration around a local stress field. In this paper, to clarify hydrogen diffusion behaviour in the square groove weld joint, a coupled analysis of heat transfer – thermal stress – hydrogen diffusion combining with α multiplication method was conducted. From these results, it was found out that for the case of a square groove weld joint, since thermal stress was not highly localized for the case of using usual value of thermal expansion coefficient of steel, hydrogen concentration behaviour is not typical. However, if thermal stress is highly localized, hydrogen was found to be localized in the side of HAZ (heat affected zone) at the interface of WM (weld metal) and HAZ and is much more typical near the outer surface side of weld joint. Hydrogen diffusion and concentration behaviours were also found to be dominated not only by local thermal stress gradient, ∇σ but also by diffusion coefficient gradient, ∇D caused by temperature difference during cooling process. In this paper, effects of these factors on hydrogen concentration were investigated based on a coupled analysis of heat transfer – thermal stress – hydrogen diffusion combining with α multiplication method.

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Effect of Pre-Heat Treatment on Hydrogen Concentration Behavior of y-Grooved Weld Joint Based on a Coupled Analysis of Heat Transfer-Thermal Stress-Hydrogen Diffusion

Volume 1A: Codes and Standards ◽

10.1115/pvp2018-84178 ◽

2018 ◽

Author(s):

Go Ozeki ◽

A. Toshimitsu Yokobori ◽

Toshihito Ohmi ◽

Tadashi Kasuya ◽

Nobuyuki Ishikawa ◽

...

Keyword(s):

Heat Transfer ◽

Heat Treatment ◽

Thermal Stress ◽

Weld Joint ◽

Hydrogen Diffusion ◽

Hydrostatic Stress ◽

Heat Transfer Analysis ◽

Coupled Analysis ◽

Cooling Process ◽

Hydrogen Induced Cracking

Hydrogen induced cracking occurs at the welded position of the structure due to concentration of hydrogen during cooling process of welding. In order to prevent the hydrogen induced cracking, Pre-Heat Treatment (PHT) is conducted. However, since PHT takes high cost, it is important to find out the suitable PHT condition based on computational mechanics. One of authors has been proposed α multiplication method which magnifies the hydrogen driving term in the diffusion equation to find out detailed behaviors of hydrogen concentration around a local stress field. In this study, in order to clarify the effect of PHT on hydrogen diffusion and concentration behaviors, a coupled analysis of heat transfer – thermal stress – hydrogen diffusion combining with α multiplication method was conducted for the model of y-grooved weld joint under various PHT conditions. This analytical method is as follows. At first, heat transfer analysis was conducted by finite difference method (FDM). And, temperature at each grid obtained by heat transfer analysis was interpolated to each node for thermal stress analysis by the finite element method (FEM). Then, thermal stress was calculated for each node using the interpolated temperature. After that, thermal stress obtained by this analysis was interpolated to each grid point for analysis of hydrogen diffusion by FDM. Using the interpolated thermal stress, stress driven hydrogen diffusion analysis was performed. By conducting sequentially these calculations mentioned above, hydrogen diffusion and concentration behaviors during cooling process were analyzed. The temperature of weld metal was 1500°C. And at initial state, hydrogen was introduced in weld metal. Thermal stress analysis was conducted under plane strain condition. As a result, hydrogen diffusion and concentration behaviour at weld joint during cooling process was found to be typical at the site of maximum hydrostatic stress and to be affected not only the gradient of hydrostatic stress but also the gradient of diffusion coefficient induced by temperature distribution.

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Hydrogen concentration behavior of y - grooved weld joint based on a coupled analysis of heat transfer - thermal stress - hydrogen diffusion

Advanced Materials Letters ◽

10.5185/amlett.2018.2160 ◽

2018 ◽

Vol 9 (10) ◽

pp. 677-683

Author(s):

Go Ozeki ◽

A. Toshimitsu Yokobori ◽

Toshihito Ohmi ◽

Tadashi Kasuya ◽

Nobuyuki Ishikawa ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

Hydrogen Concentration ◽

Weld Joint ◽

Hydrogen Diffusion ◽

Coupled Analysis ◽

Concentration Behavior

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Investigation Into Thermal Stress Characteristics of Pipe-in-Pipe Under High Temperature Condition

Volume 3A: Design and Analysis ◽

10.1115/pvp2018-84578 ◽

2018 ◽

Author(s):

Si-Hwa Jeong ◽

Min-Gu Won ◽

Nam-Su Huh ◽

Yun-Jae Kim ◽

Young-Jin Oh ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

High Temperature ◽

Temperature Distribution ◽

Heat Transfer Analysis ◽

Piping System ◽

Curved Pipe ◽

High Temperature Condition ◽

Single Pipe ◽

Radiation Conditions

In this paper, the thermal stress characteristics of the pipe-in-pipe (PIP) system under high temperature condition are analyzed. The PIP is a type of pipe applied in sodium-cooled faster reactor (SFR) and has a different geometry from a single pipe. In particular, under the high temperature condition of the SFR, the high thermal stress is generated due to the temperature gradient occurring between the inner pipe and outer pipe. To investigate the thermal stress characteristics, three cases are considered according to geometry of the support. The fully constrained support and intermediate support are considered for case 1 and 2, respectively. For case 3, both supports are applied to the actual curved pipe. The finite element (FE) analyses are performed in two steps for each case. Firstly, the heat transfer analysis is carried out considering the thermal conduction, convection and radiation conditions. From the heat transfer analysis, the temperature distribution results in the piping system are obtained. Secondly, the structural analysis is performed considering the temperature distribution results and boundary conditions. Finally, the effects of the geometric characteristics on the thermal stress in the PIP system are analyzed.

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Transient Thermal Stress Analysis of a Nonhomogeneous Plate Taking into Account the Relative Heat Transfer at Boundary Surfaces.

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A ◽

10.1299/kikaia.62.131 ◽

1996 ◽

Vol 62 (593) ◽

pp. 131-137 ◽

Cited By ~ 7

Author(s):

Yoshinobu TANIGAWA ◽

Tomikazu AKAI ◽

Ryuusuke KAWAMURA ◽

Naoki OKA

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

Stress Analysis ◽

Thermal Stress Analysis ◽

Transient Thermal Stress ◽

Transient Thermal ◽

Boundary Surfaces

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Modelling of Convective Melt Flow and Interface Shape in Commercial Bridgman-Stockbarger Growth of CdZnTe

10.1115/imece2000-1587 ◽

2000 ◽

Author(s):

Toby D. Rule ◽

Ben Q. Li ◽

Kelvin G. Lynn

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

Solute Transport ◽

Latent Heat ◽

Thermal Stresses ◽

Radiation Detector ◽

Time History ◽

High Quality ◽

Melt Convection ◽

The Impact

Abstract CdZnTe single crystals for radiation detector and IR substrate applications must be of high quality and controlled purity. The growth of such crystals from a melt is very difficult due to the low thermal conductivity and high latent heat of the material, and the ease with which dislocations, twins and precipitates are introduced during crystal growth. These defects may be related to solute transport phenomena and thermal stresses associated with the solidification process. As a result, production of high quality material requires excellent thermal control during the entire growth process. A comprehensive model is being developed to account for radiation and conduction within the furnace, thermal coupling between the furnace and growth crucible, and finally the thermal stress fields within the growing crystal which result from the thermal conditions imposed on the crucible. As part of this effort, the present work examines the heat transfer and fluid flow within the crucible, using thermal boundary conditions obtained from experimental measurements. The 2-D axisymetric numerical model uses the deforming finite element method, with allowance made for melt convection, solidification with latent heat release and conjugate heat transfer between the solid material and the melt. Results are presented for several stages of growth, including a time-history of the solid-liquid interface (1365 K isotherm). The impact of melt convection, thermal end conditions and furnace temperature gradient on the growth interface is evaluated. Future work will extend the present model to include radiation exchange within the furnace, and a transient analysis for studying solute transport and thermal stress.

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Thermo-structural analysis of a honeycomb-type volumetric absorber for concentrated solar power applications

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-03-2021-0169 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Masoud Behzad ◽

Benjamin Herrmann ◽

Williams R. Calderón-Muñoz ◽

José M. Cardemil ◽

Rodrigo Barraza

Keyword(s):

Heat Transfer ◽

Thermal Stress ◽

Steady State ◽

Discrete Model ◽

Continuum Model ◽

Transient State ◽

Operating Conditions ◽

Steady State Condition ◽

Content Type ◽

The Continuum

Purpose Volumetric air receivers experience high thermal stress as a consequence of the intense radiation flux they are exposed to when used for heat and/or power generation. This study aims to propose a proper design that is required for the absorber and its holder to ensure efficient heat transfer between the fluid and solid phases and to avoid system failure due to thermal stress. Design/methodology/approach The design and modeling processes are applied to both the absorber and its holder. A multi-channel explicit geometry design and a discrete model is applied to the absorber to investigate the conjugate heat transfer and thermo-mechanical stress levels present in the steady-state condition. The discrete model is used to calibrate the initial state of the continuum model that is then used to investigate the transient operating states representing cloud-passing events. Findings The steady-state results constitute promising findings for operating the system at the desired airflow temperature of 700°C. In addition, we identified regions with high temperatures and high-stress values. Furthermore, the transient state model is capable of capturing the heat transfer and fluid dynamics phenomena, allowing the boundaries to be checked under normal operating conditions. Originality/value Thermal stress analysis of the absorber and the steady/transient-state thermal analysis of the absorber/holder were conducted. Steady-state heat transfer in the explicit model was used to calibrate the initial steady-state of the continuum model.

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