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 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%.

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

Behavior of Exit Keyhole Diameter during Switch off Period in Plasma Keyhole Arc Welding

2018 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
Anh Nguyen Van ◽  
Tashiro Shinichi ◽  
Huu Manh Ngo ◽  
Akihisa Murata ◽  
Tadasuke Murata ◽  
...  
Keyword(s):  
Weld Pool ◽  
Arc Welding ◽  
High Speed ◽  
Video Camera ◽  
High Speed Video ◽  
High Speed Video Camera

The purpose of this investigation is to clarify the behavior of exit keyhole diameter during switch off (cutting arc) period in case of Plasma keyhole arc welding (PKAW). During switch off period, the keyhole and weld pool are visualized from backside via a high speed video camera (HSVC). The result showed that keyhole diameter on the backside is unstable. The keyhole size is much changed in X-axis. Firstly, it is increased and then it is decreased to a stationary value at t = 0.05 s after cutting arc. Meanwhile, the size in Y-axis is not changed approximately from t = 0.01 s after cutting arc. The results can be considered to control this process more efficiency.

Charged Molten Metal Droplet Deposition as a Direct Write Technology

2000 ◽  
Vol 624 ◽  
Author(s):  
M. Orme ◽  
J. Courter ◽  
Q. Liu ◽  
J. Zhu ◽  
R. Smith
Keyword(s):  
Molten Metal ◽  
High Speed ◽  
Droplet Diameter ◽  
Metal Droplet ◽  
Circuit Board ◽  
Charged Droplet ◽  
Direct Write ◽  
Direct Writing ◽  
Drop On Demand ◽  
Metal Droplets

ABSTRACTThe formation of highly uniform charged molten metal droplets from capillary stream breakup has recently attracted significant industrial and academic interest for applications requiring high-speed and high-precision deposition of molten metal droplets such as direct write technologies. Exploitation of the high droplet production rates intrinsic to the phenomenon of capillary stream break-up and the unparalleled uniformity of droplet sizes and speeds attained with proper applied forcing to the capillary stream make many new applications related to the manufacture of electronic packages, circuit board printing and rapid prototyping of structural components feasible. Recent research results have increased the stream stability with novel acoustic excitation methods and enable ultra-precise charged droplet deflection. Unlike other modes of droplet generation such as Drop-on-Demand, droplets can be generated at rates typically on the order of 10,000 to 20,000 droplets per second (depending on droplet diameter and stream speed) and can be electrostatically charged and deflected onto a substrate with a measured accuracy of ±12.5 µm. Droplets are charged on a drop-to-drop basis, enabling the direct writing of fine details at high speed. New results are presented in which fine detailed patterns are “printed” with individual molten metal solder balls, and issues relevant to the attainment of high quality printed artifacts are investigated.

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.

Heat Transfer and Fragmentation During Molten-Metal/Water Interactions

1973 ◽  
Vol 95 (4) ◽  
pp. 521-527 ◽  
Author(s):  
L. C. Witte ◽  
T. J. Vyas ◽  
A. A. Gelabert
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Liquid Nitrogen ◽  
Molten Metal ◽  
High Speed ◽  
Vapor Film ◽  
Molten Metals ◽  
Lead Zinc ◽  
Insight Into ◽  
Rapid Transfer

Molten metals, (mercury, lead, zinc, bismuth, tin, and aluminum) were quenched in water and liquid nitrogen. High-speed photographs provide insight into the fragmentation phenomenon. The key to the vapor explosion is the very rapid transfer of heat which requires substantial surface area: fragmentation provides this necessary surface area. Prior fragmentation theories are examined in light of these experiments and are found to be inadequate. This study indicates strongly that fragmentation occurs when a sample is molten and fragmentation is a response to an external stimulus. Alternate causes of fragmentation are proposed and are predicated upon the initial collapse of a vapor film around the molten metal. The data also show that energy required to form new surface area and to displace water during the fragmentation phenomenon is not significant when compared to the energy available in a molten sample.

scholarly journals Effect of Arc Pressure on the Digging Process in Variable Polarity Plasma Arc Welding of A5052P Aluminum Alloy

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1071 ◽  
Author(s):  
Bin Xu ◽  
Shinichi Tashiro ◽  
Fan Jiang ◽  
Shujun Chen ◽  
Manabu Tanaka
Keyword(s):  
Weld Pool ◽  
High Speed ◽  
Imaging System ◽  
Physical Phenomenon ◽  
Plasma Arc ◽  
Arc Pressure ◽  
Variable Polarity ◽  
Welding Stability ◽  
Energy And Momentum ◽  
Variable Polarity Plasma Arc

The keyhole digging process associated with variable polarity plasma arc (VPPA) welding remains unclear, resulting in poor control of welding stability. The VPPA pressure directly determines the dynamics of the keyhole and weld pool in the digging process. Here, through a high speed camera, high frequency pulsed diode laser light source and X-ray transmission imaging system, we reveal the potential physical phenomenon of a keyhole weld pool. The keyhole depth changes periodically corresponding to the polarity conversion period if the current is same in the electrode negative (EN) phase and electrode positive (EP) phase. There exist three distinct regimes of keyhole and weld pool behavior in the whole digging process, due to the arc pressure attenuation and energy accumulation effect. The pressure in the EP phase is smaller than that of the EN phase, causing the fluctuation of the weld pool free surface. Based on the influence mechanism of energy and momentum transaction, the arc pressure output is balanced by separately adjusting the current in each polarity. Finally, the keyhole fluctuation during the digging process is successfully reduced and welding stability is well controlled.

Extraction of Weld Pool Width Feature Based on Visual Sensing during High-Power Fiber Laser Welding

2012 ◽  
Vol 201-202 ◽  
pp. 388-391
Author(s):  
Zi Qin Chen ◽  
Xiang Dong Gao
Keyword(s):  
Laser Welding ◽  
Fiber Laser ◽  
Weld Pool ◽  
High Power ◽  
High Speed ◽  
Welding Process ◽  
304 Stainless Steel ◽  
Fiber Laser Welding ◽  
Weld Pool Width ◽  
Laser Welding Process

In a high-power fiber laser welding process, the thermal radiation of a weld pool contains plenty of information for welding quality, in which the pool width can reflect the welding stability. Thus, extracting the welding pool width of high-power fiber laser welding based on infrared thermal imaging is an important method for monitoring the weld seam quality. In this paper, we studied the 304 stainless steel welded by a 10kW high-power fiber laser continuously. A near-infrared high-speed sensing camera was used to capture the weld pool images. Image algorithms such as median filtering, gray scale stretching, cutting, dynamic threshold mathematical morphology were applied to extract the weld pool image edge, analyze and detect the weld pool width. Welding experimental results showed that the proposed methods could extract the weld pool width, which could reflect the stability status of high-power fiber laser welding process accurately.

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