scholarly journals Numerical Simulation of Constricted Sheet Tungsten Electrode Arc Characteristic with Insulating Solid Wall in Ultra Narrow Gap Welding Process

2020 ◽  
Vol 56 (2) ◽  
pp. 69
Author(s):  
LI Yuanbo ◽  
YANG Tao ◽  
ZHENG Shaoxian ◽  
ZHAO Xilong
Keyword(s):  
Numerical Simulation ◽  
Solid Wall ◽  
Welding Process ◽  
Narrow Gap ◽  
Narrow Gap Welding ◽  
Tungsten Electrode

Application of Numerical Simulation Considering the Effect of Phase Transformation to the Estimation of Hardness Distribution in Welds

2006 ◽  
Vol 512 ◽  
pp. 379-382 ◽  
Author(s):  
Yoshiki Mikami ◽  
Masahito Mochizuki ◽  
Terumi Nakamura ◽  
Kazuo Hiraoka ◽  
Masao Toyoda
Keyword(s):  
Numerical Simulation ◽  
Phase Transformation ◽  
Thermal Cycle ◽  
Welding Process ◽  
Hardness Distribution ◽  
Narrow Gap ◽  
Thermal Cycles ◽  
Narrow Gap Welding ◽  
Ultrafine Grained ◽  
Good Agreement

This study investigated a method for estimating hardness distribution in welds, considering the effect of phase transformation and weld thermal cycles. Hardness distribution in welds was estimated from fractions and hardness of each microstructure by using rule of mixture. Finite element heat conduction analysis was performed to calculate weld thermal cycles. Microstructures formed corresponding to the thermal cycle were also calculated based on the continuous cooling transformation (CCT) diagram. The method mentioned above was applied to welds of Ultra-Narrow Gap welding process, which was developed for welding of ultrafine-grained steels. The calculated thermal cycles in the welds corresponded with measured results. Moreover, the estimated hardness distribution in the welds, which were estimated by using calculated thermal cycles and the phase fraction of each microstructure, was also in good agreement with measured values.

scholarly journals Extension of the process limits in laser beam welding of thick-walled components using the Laser Multi-Pass Narrow-Gap welding (Laser-MPNG) on the example of the nickel-based material Alloy 617 occ

2021 ◽  
Author(s):  
Benjamin Kessler ◽  
Dirk Dittrich ◽  
Berndt Brenner ◽  
Jens Standfuss ◽  
Christoph Leyens
Keyword(s):  
Laser Beam ◽  
Low Cycle Fatigue ◽  
Laser Beam Welding ◽  
Welding Process ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Narrow Gap ◽  
Narrow Gap Welding ◽  
Alloy 617 ◽  
First Time

AbstractThe joining of thick-walled components using beam-based joining techniques is content of worldwide research and development activities, but has not yet been established in industry. State of the art to weld nickel super alloys is currently a TIG narrow-gap welding. The present paper is focusing on a new specific laser beam welding process, the so-called Laser Multi-Pass Narrow-Gap welding (Laser-MPNG). It first explains the process principle based on 2D beam oscillation, the use of fiber lasers and the multi-pass principle. The potential of the Laser-MPNG welding process is demonstrated using the technically significant nickel-based material Alloy 617 occ. As a result, it was possible for the first time to realize a weld with a wall thickness of 140 mm free of cracks or bonding defects. Promising results of creep and low-cycle fatigue tests are used to show the potential that Laser-MPNG welded joints would have for future industrial applications.

scholarly journals The Mechanism of Effect of Flux Bands on The Arc Behavior in Flux Bands Constricting Arc Welding Process

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1652
Author(s):  
Lei Wang ◽  
Jisen Qiao ◽  
Jianhong Chen
Keyword(s):  
Arc Welding ◽  
Solid Wall ◽  
Welding Process ◽  
Welding Current ◽  
Narrow Gap ◽  
The Core ◽  
Arc Behavior ◽  
Before And After ◽  
Arc Shape ◽  
Arc Welding Process

A new welding method, flux bands constricting arc (FBCA) welding, is proposed to compensate for the shortage of insufficient weld width of laser welding T-joints in high steel sandwich panels. The arc behavior (arc burning position, arc shape, arc heat, and arc stability) before and after sticking the flux bands (GMAW and FBCA welding) to the ultra-narrow gap groove was tested. Results indicate that flux bands have solid-wall constricting effect (SWCE) and thermo-compression effect (TCE) on the arc and self-producing slag and gas function in FBCA welding. In ultra-narrow gap groove, the arc burning position climbing up phenomenon (APCP) occurs without flux bands. The SWCE of flux bands on the arc effectively suppresses the APCP because of the insulation of flux bands. In the FBCA welding process, the effective heating area of the arc is increased by at least 5 mm2 compared with that in GMAW. When the groove gap decreases, flux bands not only compress the arc from an inverted bell shape to a rectangular shape, but also make the 660 °C isotherm on the core-plate to increase from 3 mm to 8 mm. In the end, the proportion of unstable arc burning time is reduced by 86.85%, the fluctuation of arc voltage and welding current are also significantly reduced by the flux bands because of their SWCE on the arc.

Numerical Welding Simulation of a Vessel Head Adapter: Influence of Modelling Assumptions

2016 ◽  
Author(s):  
Sébastien Gallee ◽  
Vincent Robin ◽  
Florence Gommez ◽  
Stéphan Courtin ◽  
Alexandre Brosse ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Welding Process ◽  
Nuclear Industry ◽  
Central Position ◽  
Narrow Gap ◽  
Special Investigation ◽  
Residual Stress State ◽  
Component Design ◽  
Modelling Assumptions ◽  
Welding Processes

In nuclear industry, most of heavy components and reactor coolant lines have a large thickness and their manufacturing processes require multi-pass welding. When low-alloy steel components are concerned, the assembly process is often performed in several stages, such as a cladding, a buttering and a Post Weld Heat Treatment (PWHT) before joining two materials without phase transformations. The distortions induced by the welding operation might be an issue and residual stresses could be significant and play a role on the weldability. For these reasons, AREVA has placed a lot of effort to improve the reliability of numerical simulation of its welding processes, in order to have a better understanding of the involved phenomena and also to predict the residual stress state through the structure [1], [2] and [3] because this numerical simulation can be used to select the manufacturing process in the early phase of welded component design. The aim of the simulations presented in this paper is the investigation of the final residual state of a nozzle placed at the central position of the vessel head. The computations are performed according a robust methodology packaged in AREVA OSS tool [4] which is based on SYSWELD™ Finite Element solver [5]. Two welding configurations are investigated. The first one is a mock-up with an “open” narrow gap, the groove filling being performed by a manual welding process using electrode coatings. The second one is a mock-up with a “closed” narrow gap, the groove filling being performed by an automatic TIG process. After the comparison of these two configurations, a special investigation is performed on the “open” narrow gap mock-up. The influence of the vessel head buttering before the groove filling is investigated, as well as the efficiency of the PWHT performed after the buttering operation.

Modeling of weld formation in variable groove narrow gap welding by rotating GMAW

2020 ◽  
Vol 57 ◽  
pp. 163-173
Author(s):  
Wenhang Li ◽  
Chengfu He ◽  
Jinshan Chang ◽  
Jiayou Wang ◽  
Jing Wu
Keyword(s):  
Narrow Gap ◽  
Narrow Gap Welding ◽  
Weld Formation
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