scholarly journals Metal Transfer Mechanisms in Hot-Wire Gas Metal Arc Welding

2020 ◽  
Vol 99 (11) ◽  
pp. 281s-294s
Author(s):  
P. P. G. RIBEIRO ◽  
◽  
P. D. C. ASSUNÇÃO ◽  
E. M. BRAGA ◽  
R. A. RIBEIRO ◽  
...  
Keyword(s):  
Cross Sections ◽  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Melting Rate ◽  
Bead Geometry ◽  
Hot Wire ◽  
High Speed Imaging ◽  
Metal Arc Welding ◽  
Full Factorial

The hot-wire gas metal arc welding (HW-GMAW) process is widely used to increase the melting rate of a secondary wire through Joule heating without significantly increasing the total heat input to the substrate. Because there is limit-ed knowledge regarding the associated arc dynamics and its influence on bead geometry, the present study considers how these are affected by the hot-wire polarity (negative or positive), hot-wire feed rate, and hot-wire orientation using a two-factor full factorial experiment with three replicates. During welding, high-speed imaging synchronized with current and voltage acquisition to study the arc dynamics. After this, each replicated weld was cut into three cross sections, which were examined by standard metallography. The preliminary results suggest that the arc was stable within the range of process parameters studied. The arc polarity played a role on arc position relative to the hot wire, with a decrease in penetration depth observed when the arc was attracted to the hot wire.

scholarly journals Globular-to-Spray Transition in Cold Wire Gas Metal Arc Welding

2021 ◽  
Vol 100 (4) ◽  
pp. 121-131
Author(s):  
R. A. RIBEIRO ◽  
◽  
P. D. C. ASSUNÇÃO ◽  
E. B. F. DOS SANTOS ◽  
E. M. BRAGA ◽  
...  
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Current ◽  
Electrical Current ◽  
Feed Speed ◽  
High Speed Imaging ◽  
Transition Mechanism ◽  
Cold Wire ◽  
Metal Arc Welding

The electrical current required for a transition from globular to spray droplet transfer during gas metal arc welding (GMAW) is determined by the specified wire feed speed in the case of constant-voltage power supplies. Generally, in narrow groove welding, spray transfer is avoided, be-cause this transfer mode can severely erode the groove sidewalls. This work compared the globular-to-spray transition mechanism in cold wire gas metal arc welding (CW-GMAW) vs. standard GMAW. Synchronized high-speed imaging with current and voltage samplings were used to characterize the arc dynamics for different cold wire mass feed rates. Subsequently, the droplet frequency and diameter were estimated, and the parameters for a globular-to-spray transition were assessed. The results suggest that the transition to spray occurs in CW-GMAW at a lower current than in the standard GMAW process. The reason for this difference appears to be linked to an enhanced magnetic pinch force, which is mainly responsible for metal transfer in higher welding current conditions.

Mechanically assisted droplet transfer process in gas metal arc welding

2002 ◽  
Vol 216 (4) ◽  
pp. 555-564 ◽  
Author(s):  
Y Wu ◽  
R Kovacevic
Keyword(s):  
Transfer Process ◽  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Droplet Transfer ◽  
Macroscopic Appearance ◽  
Transfer Mode ◽  
Metal Arc Welding ◽  
Separate Control

Gas metal arc welding has been generally accepted as the preferred joining technique due to its advantages in high production and automated welding applications. Separate control of arc energy and arc force is an essential way to improve the welding quality and to obtain the projected metal transfer mode. One of the most effective methods for obtaining separate control is to exert an additional force on the metal transfer process. In this paper, the droplet transfer process with additional mechanical force is studied. The welding system is composed of an oscillating wire feeder. The images of molten metal droplets are captured by a high-speed digital camera, and both the macroscopic appearance and the cross-sectional profiles of the weld beads are analysed. It is shown that the droplet transfer process can be significantly improved by wire electrode oscillation, and a projected spray transfer mode can be established at much lower currents. By increasing the oscillation frequency, the droplet transfer rate increases while the droplet size decreases. In addition, the improvement in the droplet transfer process with wire oscillation leads to an enhancement of the surface quality and a modification of the geometry of the weld beads that could be of importance for overlay cladding and rapid prototyping based on deposition by welding.

Metal Transfer in Double-Electrode Gas Metal Arc Welding

2007 ◽  
Vol 129 (6) ◽  
pp. 991-999 ◽  
Author(s):  
Kehai Li ◽  
YuMing Zhang
Keyword(s):  
Base Metal ◽  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
High Melting ◽  
High Productivity ◽  
Spray Transfer ◽  
Metal Arc Welding ◽  
Double Electrode ◽  
Melting Current

Gas metal arc welding (GMAW) is the most widely used process for metal joining because of its high productivity and good quality, but analysis shows that the fundamental characteristic restricts conventional GMAW from further increasing the welding productivity. A novel GMAW process, refereed to as double-electrode GMAW or DE-GMAW, thus has been developed to make it possible to increase the melting current while the base metal current can still be controlled at a desired level. This fundamental change provides an effective method to allow manufacturers to use high melting currents to achieve high melting speed and low base metal heat input. A series of experiments have been conducted to uncover the basic characteristics of this novel process. Results obtained from analyses of high-speed image sequences and recorded current signals suggest that DE-GMAW can lower the critical current for achieving the desired spray transfer, shift the droplet trajectory, reduce the diameter of the droplet, and increase the speed and (generation) rate of the droplets.

An Evaluation System of Pulsed GMAW Process

2013 ◽  
Vol 483 ◽  
pp. 599-602
Author(s):  
Ying Gao ◽  
Jing Hua Han ◽  
Li Yan Lou ◽  
Huan Li
Keyword(s):  
Arc Welding ◽  
Evaluation System ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Electric Signal ◽  
Characteristic Parameters ◽  
Display Module ◽  
Metal Arc Welding ◽  
Labview Platform

A process evaluation system for pulsed gas metal arc welding (GMAW-P) based on the LabVIEW platform has been developed. This system is comprised of two modules, a simultaneous display module and a data analysis module. Using these modules, the system can not only provide a comprehensive direct viewing display of the welding electric signal and high speed camera photo, but also can analyze the characteristic parameters of the welding process. The results show that the system works properly.

scholarly journals Investigation of Welds and Heat Affected Zones in Weld Surfacing Steel Plates Taking into Account the Bead Sequence

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5666
Author(s):  
Miloš Mičian ◽  
Jerzy Winczek ◽  
Marek Gucwa ◽  
Radoslav Koňár ◽  
Miloslav Málek ◽  
...  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Steel Plates ◽  
Structural Components ◽  
Maximum Hardness ◽  
Qualitative And Quantitative ◽  
Metal Arc Welding ◽  
The Individual

In this paper, the experimental investigation results of the bead sequence input on geometry, structure, and hardness of surfaced layers after multi-pass weld surfacing are analyzed. Three S355 steel plates surfaced by GMAW (Gas Metal Arc Welding) were tested with three different combinations of six beads. The geometric, structural, and hardness analysis was carried out in the cross-section of the plates in the middle of the welded layers. The dimensions of padded layers, fusion and heat-affected zone, as well as the individual padded weld were evaluated. On the basis of metallographic samples, qualitative and quantitative structure analysis was performed. Hardness measurements in surfacing welds and heat-affected zones in the tested cross-sections of the surfacing layers were carried out. A comparative analysis of structure and hardness, taking into account the thermal implications of the bead sequence, allowed for the formulation of conclusions. Comparative studies have shown differences in properties between heat-affected zones (HAZ) for individual surfacing sequences. These differences were mainly in the dimensions of the surfacing layers, the share of structural components, as well as the uniformity of hardness distributions. Finally, the most favorable sequence in terms of structure and hardness distribution, maximum hardness, and range of hardness has been indicated.

Modelling of bead hump formation in high speed gas metal arc welding

2016 ◽  
Vol 21 (8) ◽  
pp. 700-710 ◽  
Author(s):  
Guoxiang Xu ◽  
Qingnan Cao ◽  
Qingxian Hu ◽  
Weiwei Zhang ◽  
Peng Liu ◽  
...  
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Metal Arc Welding

Arc Interruptions in Tandem Pulsed Gas Metal Arc Welding

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Ruham Pablo Reis ◽  
Daniel Souza ◽  
Demostenes Ferreira Filho
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Electrical Current ◽  
Gas Tungsten Arc ◽  
Metal Arc Welding ◽  
Two Factors ◽  
Single Arc ◽  
Mean Current

In addition to electromagnetic attraction between the arcs in Tandem Pulsed gas metal arc welding (GMAW), arc interruptions, mostly in the trailing arc at low mean current levels, may also occur, which is a phenomenon not widely discussed in the welding field. These arc interruptions must be avoided, since they also represent interruptions in metal fusion and deposition during the welding process, leading to lack of fusion/penetration and/or deposition flaws, adding cost for repairing operations. To improve the understanding on arc interruptions in Tandem Pulsed GMAW and how the current pulsing synchronism between the arcs relates to this phenomenon, this work proposes to evaluate the influence of parameters of adjacent arcs (Tandem Pulsed GMAW) and also of a single arc (GTAW—gas tungsten arc welding), but similarly subjected to magnetic deflection, on the occurrence of arc interruptions/extinctions. High-speed filming was used to help understand the interruption/extinction mechanism. In the case of Tandem Pulsed GMAW, the pulses of current of the leading and trailing arcs need to be almost-in-phase to prevent interruptions in the trailing arc. The distance of 10 mm between the adjacent arcs helped reduce the incidence of trailing arc interruptions, yet keeping a sound weld visual quality. In the case of GTAW, the higher the electrical current flowing through the arcs and the shorter their lengths, the more they resist to the extinction. The trailing arc interruptions in Tandem Pulsed GMAW seem to be determined by the deflection and heat in this arc, and their prevention can be achieved by a balance between these two factors, which is reached by synchronized pulsing currents.

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