scholarly journals Impact of the Chemical Elements Upon the Convective Flows in the Molten Metal of the Weld Pool

2017 ◽  
Vol 66 ◽  
pp. 012017 ◽  
Author(s):  
V D Sarychev ◽  
D A Chinakhov ◽  
S A Solodsky ◽  
A Yu Granovskii ◽  
S A Nevskii
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
Chemical Elements ◽  
Convective Flows

scholarly journals Incompressible SPH Simulation of Weld Pool Convection with Molten Metal Droplets in a GMA Welding

2015 ◽  
Vol 33 (4) ◽  
pp. 332-340 ◽  
Author(s):  
Hisaya KOMEN ◽  
Masaya SHIGETA ◽  
Manabu TANAKA ◽  
Yu FUKUNISHI
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
Gma Welding ◽  
Incompressible Sph ◽  
Sph Simulation ◽  
Metal Droplets

scholarly journals Fluid Flow Characteristics and Weld Formation Quality in Gas Tungsten Arc Welding of a Thick-Sheet Aluminum Alloy Structure by Varying Welding Position

2018 ◽  
Vol 8 (8) ◽  
pp. 1215 ◽  
Author(s):  
Baohua Chang ◽  
Hong Xiao ◽  
Jinle Zeng ◽  
Shuo Yang ◽  
Dong Du ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Molten Metal ◽  
Weld Pool ◽  
Flow Characteristics ◽  
Sheet Thickness ◽  
Thick Sheet ◽  
Weld Formation ◽  
Sheet Aluminum ◽  
Weld Pools ◽  
Welding Position

This study aims to reveal the cause of different weld formation quality for varying welding position in the GTAW (Gas Tungsten Arc Welding) of a thick-sheet aluminum alloy structure. The fluid flow characteristics of weld pools are investigated by CFD (Computational Fluid Dynamic) modeling and high-speed imaging for the climbing and flat welding positions, which correspond to the start and finish ends of the welds of the structure, respectively. Results show that the directions of gravity relative to weld pools may notably affect the fluid flows in weld pools for different welding positions. For flat welding, gravity will accelerate the fluid flow in the direction of sheet thickness only and in turn result in a high velocity downwards, which implies a good penetrating capability. Welds of good formation with smooth surface and consistent width can be produced under flat welding position. In contrast, for climbing welding, gravity will act on the molten metal in both the direction of sheet thickness and the lateral direction of the weld pool. As a result, the velocity in sheet-thickness direction is decreased, which implies a decreased penetrating capability. Meanwhile, the velocity backwards is increased in the top portion of the weld pool, which makes the molten metal apt to flow out of the weld pool. Both the decreased penetrating capability and the accelerated molten metal outflow would render the climbing welding process unstable, and result in welds of poor formation with uneven weld surface and inconsistent weld width. Based on the study, possible methods are proposed that could be used to improve the weld formation quality when welding thick-sheet aluminum alloys structures using various welding positions.

scholarly journals Numerical Simulation and Industrial Application of High Speed Tandem TIG Welding

2021 ◽  
Author(s):  
Dongsheng Wu ◽  
Jiuling Huang ◽  
Kong Liang ◽  
Xueming Hua ◽  
Min Wang ◽  
...  
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
High Speed ◽  
Metal Flow ◽  
Welding Process ◽  
Tig Welding ◽  
Pool Surface ◽  
Weld Pool Surface ◽  
Welding Processes ◽  
Molten Metal Flow

Abstract Self-developed high speed tandem TIG welding equipment were adopted to manufacture titanium welded tubes with high efficiency and high quality. The joint made by this high efficient welding process met Chinese standard requirements. A coupled electrode, arc and weld pool numerical model was also developed to investigate temperature and velocity distributions, and energy propagation of this welding process. The numerical results showed that the Marangoni stress was much higher than the arc shear stress, and was mainly positive after leading and trailing arcs in the x and y directions, so the molten metal flowed backward on the top weld pool surface. Previous studies proposed that a “pull-push” flow pattern defined as a backward molten metal flow after the leading arc and a forward molten metal flow before the trailing arc existed on the top weld pool surface in tandem arc welding processes, while it was not observed in this case. The calculated arc efficiency of the high speed tandem TIG welding was about 79.8%.

Backward flowing molten metal in weld pool and its influence on humping bead in high-speed GMAW

2016 ◽  
Vol 237 ◽  
pp. 342-350 ◽  
Author(s):  
Lin Wang ◽  
Ji Chen ◽  
Chuansong Wu ◽  
Jinqiang Gao
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
High Speed

scholarly journals GAS-DYNAMIC EFFECT OF THE ARC ON THE METAL OF THE WELD POOL DURING NON-CONSUMABLE ELECTRODE WELDING (REWIEW)

2021 ◽  
pp. 60-63
Author(s):  
A. V. Savinov ◽  
O. A. Polesskiy ◽  
A. A. Chudin ◽  
P. P. Krasikov ◽  
L. S. Krasikova ◽  
...  
Keyword(s):  
Molten Metal ◽  
Weld Pool ◽  
Liquid Layer ◽  
Arc Discharge ◽  
Dynamic Effect ◽  
Current Strength ◽  
Consumable Electrode ◽  
Shielding Gas ◽  
Gas Dynamic

Based on the analysis of the literature data, the influence of the composition of the shielding gas, the voltage across the arc, the current strength on the power (gas-dynamic) effect of an arc discharge with a non-consumable electrode, the thickness of the liquid layer of the molten metal, and the depth of the crater of the weld pool are shown.

Exothermic Additions in a Tubular Covered Electrode and Oxidizing Reactions Influence on Underwater Wet Welding

2007 ◽  
Author(s):  
Ezequiel C. P. Pessoa ◽  
Alexandre Q. Bracarense ◽  
Stephen Liu
Keyword(s):  
Weld Metal ◽  
Weld Pool ◽  
Chemical Elements ◽  
Welding Process ◽  
Oxidation Reactions ◽  
Fca Welding ◽  
Underwater Wet Welding ◽  
Metal Composition ◽  
External Covering ◽  
Weld Metal Composition

During Underwater Wet Welding (UWW), the water that surrounds the arc decomposes liberating large amount of hydrogen and oxygen. As a consequence of the presence of these gases in the arc atmosphere and weld pool, porosity in the weld metal occurs. In the past years, many research programs had been carried out with the objective to reduce or eliminate porosity in wet welds. A simple way to accomplish this goal is using chemical elements or ingredients to promote or avoid certain chemical reactions in the weld pool. In conventional stick (shielded metal arc - SMA) electrodes, it is possible to add alloying elements or other ingredients through the external covering. A tubular covered electrode (TCE) (a hybrid process between SMA and flux cored arc - FCA welding) allows the addition of reactive elements in the hollow rod, separate from the other ingredients used in the flux covering. This way, it is possible to use exothermic elements, placed inside the tube, to control the oxidation reactions, but limiting these reactions to the arc plasma and in the weld pool. Exothermic additions in welding consumables can promote desirable oxidation reactions, change the metal transfer mode, reduce the cooling rate, and decrease the electrical dependence of the welding process. Theoretically, the application of flux cored shielded metal arc (FC-SMA) welding with exothermic additions will permit better control the weld metal composition and reduce the porosity in wet welds. This paper describes underwater wet welding with tubular covered electrodes that contain exothermic additions such as (CaC2) and aluminum (A1), and the influence of these ingredients on weld metal composition and porosity.

scholarly journals Effect of Viscosity on the GTA Welds Bead Penetration in Relation with Surface Tension Elements

2016 ◽  
Vol 6 (2) ◽  
pp. 952-955
Author(s):  
K. Touileb ◽  
R. Djoudjou ◽  
A. Ouis
Keyword(s):  
Surface Tension ◽  
Stainless Steel ◽  
Viscous Dissipation ◽  
Molten Metal ◽  
Weld Pool ◽  
Marangoni Convection ◽  
Solid Compounds ◽  
Different Content ◽  
Bead Penetration

The aim of this paper is to study the effect of the viscous dissipation on the surface tension and its role on the shape of weld pool. Experiments were conducted on four different casts of ferritic stainless steel with different content in the sulfur and titanium. The results show in particular that the presence of titanium solid compounds affects the role of sulfur as surfactant element. Titanium in the presence of carbon and oxygen, titanium forms solid compounds which affect the Marangoni convection due to the sulfur element in the weld pool. The viscous dissipation due to these compounds alters the flow rate of the molten metal. We expect that the viscosity of metal liquid was altered by these solid compounds. The viscous dissipation due to these compounds contributes to heat the molten metal leading to larger weld bead.

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

1976 ◽  
Vol 32 ◽  
pp. 169-182
Author(s):  
B. Kuchowicz
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Fission Products ◽  
Abundance Pattern ◽  
Isotopic Shifts ◽  
Processed Material ◽  
R Process ◽  
Ap Stars ◽  
Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Quantitative parallel EELS spectrum imaging developed as a new tool in AEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1202-1203
Author(s):  
Gianluigi Botton ◽  
Gilles L'espérance
Keyword(s):  
Statistical Analysis ◽  
Spatial Resolution ◽  
Personal Computer ◽  
Systematic Study ◽  
Present Author ◽  
Chemical Elements ◽  
Detection Limits ◽  
Research Groups ◽  
Quantitative Performance ◽  
Spectrum Imaging

As interest for parallel EELS spectrum imaging grows in laboratories equipped with commercial spectrometers, different approaches were used in recent years by a few research groups in the development of the technique of spectrum imaging as reported in the literature. Either by controlling, with a personal computer both the microsope and the spectrometer or using more powerful workstations interfaced to conventional multichannel analysers with commercially available programs to control the microscope and the spectrometer, spectrum images can now be obtained. Work on the limits of the technique, in terms of the quantitative performance was reported, however, by the present author where a systematic study of artifacts detection limits, statistical errors as a function of desired spatial resolution and range of chemical elements to be studied in a map was carried out The aim of the present paper is to show an application of quantitative parallel EELS spectrum imaging where statistical analysis is performed at each pixel and interpretation is carried out using criteria established from the statistical analysis and variations in composition are analyzed with the help of information retreived from t/γ maps so that artifacts are avoided.

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