scholarly journals Construction of metal transfer modes maps for an ER4130 filler metal in GMAW process

DYNA ◽  
2020 ◽  
Vol 87 (215) ◽  
pp. 126-135
Author(s):  
Jorge Enrique Giraldo Barrada ◽  
Juan Camilo García Viana ◽  
John Edison Morales Galeano ◽  
Emanuel Valencia Henáo
Keyword(s):  
Signal Analysis ◽  
Filler Metal ◽  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Drop Diameter ◽  
Shielding Gas ◽  
Low Resolution ◽  
Aisi 4130

Metal transfer modes (MTMs) maps were constructed for GMAW process using ER4130 and 98%Ar-2%O2 shielding gas. There is no available MTMs maps for this filler metal which is used to obtain matching strength in welds of AISI 4130/4140 steels. These maps serve as tools to establish the MTM given a welding current and voltage, which is useful when an engineer is trying to qualify welding procedures according to construction codes. The maps were built analyzing current and voltage signals recorded at 5000 samples/second during bead-on-plate welds. The main advantage of this methodology is its simplicity of instrumentation without expensive cameras, but has low resolution and it is difficult to identify finer characteristics of MTMs, such as subgroups (repelled globular, streaming, rotational spray), drop diameter, explosive transfer, etc. Several MTMs were identified in the signal analysis and grouped into natural MTMs (short circuit, globular and spray) and interchangeable modes (short-circuit-globular, globular-spray and short-circuit-globular-spray).

Study on Metal Transfer and Welding Spatter Characteristics of Basic Flux Cored Wire

2013 ◽  
Vol 477-478 ◽  
pp. 1369-1372 ◽  
Author(s):  
Yong Wang ◽  
Ying Qiao Zhang ◽  
Bao Wang ◽  
Zhi Jun Wang
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Welding Parameters ◽  
Droplet Transfer ◽  
Cored Wire ◽  
Basic Flux ◽  
Key Factor ◽  
Slag Column

The metal transfer behaviors of basic flux cored wire at different arc voltage and welding current and the resultant welding spatter were investigated by using a high speed camera. Two modes of metal transfer are found: globular repelled transfer (lower welding parameters) and small droplet transfer (higher welding parameters). The former is accompanied by large granular spatter, large droplet itself explosion spatter and electric explosive spatter of short-circuit, and spatter in the latter is reduced obviously. But if the slag column is found in the two models, spatter could be dropped evidently owing to its significant guiding role for metal transfer. Therefore the slag column is the key factor of reducing welding spatter.

scholarly journals Analysis of the Arc Current of CMT Brazing Process

2018 ◽  
Vol 26 (42) ◽  
pp. 103-108
Author(s):  
Miloš Mičian ◽  
Milan Marônek
Keyword(s):  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Point Of View ◽  
Cold Metal Transfer ◽  
Digital Oscilloscope ◽  
Software Applications ◽  
Cmt Welding ◽  
Arc Current ◽  
Cold Metal

Abstract The system with short circuiting metal transfer in comparison to common MIG/MAG process was introduced as CMT (Cold Metal Transfer) process by the Fronius company in 2004. The paper deals with the arc current analysis of the CMT process during MIG brazing of automotive components. The TPS 5000 CMT power source together with VR 7000 CMT wire feeder, Robacta Drive CMT welding torch and CuAl 5 Ni 2, Ø1 mm filler metal were used. In order to monitor the welding current, the galvanic separator WS 1.0, digital oscilloscope ETC M621 and IBM notebook with software applications ETC Scope M621 were engaged. A current waveform in the stage D at the time of 5s from the brazing process beginning within duration of 50 ms was closely analysed. The analysis revealed the total ratio of the arc burning to the total brazing time to be approximately 26%. The starting and ending phases of short-circuit were performed at decreased current (approximately 34 to 38 % of the current value during arc burning), which was very positive from the transient effect point of view, and could not be proclaimed for the conventional short-circuit droplet transfer modes.

scholarly journals Influence of Metal Transfer Stability and Shielding Gas Composition on CO and CO2 Emissions during Short-circuiting MIG/MAG Welding

2016 ◽  
Vol 21 (3) ◽  
pp. 253-268
Author(s):  
Valter Alves de Meneses ◽  
Valdemar Silva Leal ◽  
Américo Scotti
Keyword(s):  
Short Circuit ◽  
Metal Transfer ◽  
Mag Welding ◽  
Gas Composition ◽  
Breathing Zone ◽  
Shielding Gas ◽  
Residual Concentration ◽  
Average Current ◽  
High Level ◽  
Welding Processes

Abstract: Several studies have demonstrated the influence of parameters and shielding gas on metal transfer stability or on the generation of fumes in MIG/MAG welding, but little or nothing has been discussed regarding the emission of toxic and asphyxiating gases, particularly as it pertains to parameterization of the process. The purpose of this study was to analyze and evaluate the effect of manufacturing aspects of welding processes (short-circuit metal transfer stability and shielding gas composition) on the gas emission levels during MIG/MAG welding (occupational health and environmental aspects). Using mixtures of Argon with CO2 and O2 and maintaining the same average current and the same weld bead volume, short-circuit welding was performed with carbon steel welding wire in open (welder’s breathing zone) and confined environments. The welding voltage was adjusted to gradually vary the transfer stability. It was found that the richer the composition of the shielding gas is in CO2, the more CO and CO2 are generated by the arc. However, unlike fume emission, voltage and transfer stability had no effect on the generation of these gases. It was also found that despite the large quantity of CO and CO2 emitted by the arc, especially when using pure CO2 shielding gas, there was no high level residual concentration of CO and CO2 in or near the worker’s breathing zone, even in confined work cells.

Effect of Helium Addition in Argon Shielding Gas on Metal Transfer Behavior in Gas Metal Arc Welding of Aluminum

2013 ◽  
Vol 545 ◽  
pp. 219-224 ◽  
Author(s):  
Pakpoom Jittavisuttiwong ◽  
Bovornchok Poopat
Keyword(s):  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Gas Mixture ◽  
Spray Transfer ◽  
Arc Voltage ◽  
Pure Argon ◽  
Transfer Mode ◽  
Transfer Behavior ◽  
Current Region

Helium is widely used as mixing with argon for a shielding gas in GMAW process of Aluminum in order to improve weld quality and increase heat transfer to the weld pool. It has been known that helium could affect metal transfer behavior; however, its behavior has not been well understood. In this study, an analysis of the metal transfer behavior in the GMAW of aluminum was studied. The main objective is to study the effect of Helium on metal transfer in two main regions, short circuit (low welding current region) and spray transfer (high current region). The composition of 5 types of shielding gases were pure argon, 75%Ar + 25%He, 50%Ar + 50%He, 25%Ar + 75%He and pure helium. The welding parameters were fixed at 90A/17.0V, 100A/18.2V, 140A/24.6V and 180A/27.6V. Aluminum plates were welded bead-on-plate in a flat position. The metal transfer behavior was analyzed by using acoustic signals and arc voltage signals. For the result, at low welding current of 90A and 100A with pure argon, short-circuit transfer mode was observed. Adding helium in gas mixture gave no effect in metal transfer mode in low welding current regions but the metal transfer rate was slightly increased. At high welding currents of 140A and 180A with pure argon, spray transfer mode was observed and when increasing helium in gas mixture resulted in changing from spray transfer to combined mode of spray-globular. In these high welding currents, adding helium in gas mixture resulted in decreasing the metal transfer rate since helium gas tended to promote globular metal transfer. Acoustic signal and arc voltage signal can be used effectively in determining modes of metal transfer.

scholarly journals The Effect of the Use of PTFE as a Covered-Electrode Binder on Metal Transfer

2015 ◽  
Vol 20 (2) ◽  
pp. 160-170 ◽  
Author(s):  
Cláudio Turani Vaz ◽  
Alexandre Queiroz Bracarense
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Outer Edge ◽  
Polymer Binder ◽  
Electrode Binder ◽  
Covered Electrodes ◽  
Weld Metal Microstructure ◽  
Metal Microstructure

AbstractStudies have shown that when used as binders for basic covered electrodes, polymers produce a weld metal microstructure with a high acicular ferrite content. The reasons identified for this behavior include changes in the shielding atmosphere and metal transfer mode. To investigate the effect of polymers on metal transfer, voltage oscillograms and high-speed films were recorded during welding with standard-binder and polymer-binder E7018 electrodes using different welding currents. Electrodes tips collected after the arc had been abruptly interrupted were examined metallographically. For electrodes with a polymer binder, the short-circuit frequency was lower regardless of the welding current used and decreased as welding current increased. In many events characterized as short circuits in the voltage oscillograms for polymer-binder electrodes, metal transfer in fact occurred without any arc interruption. The angle between the outer edge of the metal drop and the inner edge of the coating crater showed that the polymer increased the intensity of the plasma jet, and the pinch effect observed during welding using the polymer-binder electrode indicated that there were changes in surface tension and electromagnetic force.

Analytical Modeling of Metal Transfer for GMAW in the Globular Mode

2008 ◽  
Author(s):  
U. Ersoy ◽  
S. J. Hu ◽  
E. Kannatey-Asibu
Keyword(s):  
Gas Metal Arc Welding ◽  
Variable Mass ◽  
Welding Current ◽  
Metal Transfer ◽  
Model Parameters ◽  
Feeding Rates ◽  
Cycle Times ◽  
Metal Arc Welding ◽  
Wire Feeding ◽  
Spring Coefficient

A lumped parameter dynamical model is developed to describe the metal transfer for gas metal arc welding (GMAW) in the globular mode. The oscillations of molten drop are modeled using a mass-spring-damper system with variable mass and spring coefficient. An analytical solution is developed for the variable coefficient system to better understand the effect of various model parameters on the drop oscillations. The effect of welding drop motion on the observed current and voltage signals is investigated and the model agrees well with the experimental results. Furthermore, the effect of wire feeding rate (or welding current) on the metal transfer cycle time is studied and the model successfully estimates the cycle times for different wire feeding rates.

Effect of Current Waveform on Metal Transfer in Controlled Short Circuiting Gas Metal Arc Welding

2013 ◽  
Vol 718-720 ◽  
pp. 202-208 ◽  
Author(s):  
Mao Ai Chen ◽  
Yuan Ning Jiang ◽  
Chuan Song Wu
Keyword(s):  
Transfer Process ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Current ◽  
Metal Transfer ◽  
Arc Voltage ◽  
Metal Arc Welding ◽  
Maximum Stability ◽  
The Stability ◽  
Welding Inverter

With high-speed welding inverter and precisely controlling the welding current with arc-bridge state, advanced pulse current waveforms can be produced to optimize the transfer characteristics of short circuiting transfer welding. In this paper, the images of droplet/wire, and the transient data of welding current and arc voltage were simultaneously recorded to study the influence of peak arcing current, background arcing current and tail-out time on the stability of short circuiting transfer process. It was found that maximum short circuiting transfer stability is reached under specific welding conditions. Any deviation from these conditions will cause abnormal rises in arc voltage indicating instantaneous arc extinguishing and greater spatter. Optimal welding conditions were obtained to achieve the maximum stability of short circuiting metal transfer process.

Influence of Metal Transfer Behavior Under Ar And CO2 Shielding Gases On Geometry And Surface Roughness of Single And Multilayer Structures In GMAW-Based Wire Arc Additive Manufacturing of Mild Steel

2021 ◽  
Author(s):  
Mitsugu Yamaguchi ◽  
Rikiya Komata ◽  
Tatsuaki Furumoto ◽  
Satoshi Abe ◽  
Akira Hosokawa
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Molten Pool ◽  
Multilayer Structure ◽  
Short Circuit ◽  
Metal Transfer ◽  
Geometric Accuracy ◽  
Transfer Behavior ◽  
Ar Gas ◽  
Wire Arc Additive Manufacturing

Abstract Wire arc additive manufacturing (WAAM) is advantageous for fabricating large-scale metallic components, however, a high geometric accuracy as that of other AM techniques cannot be achieved because of the deposition process with a large layer. This study focuses on the WAAM process based on gas metal arc welding (GMAW). To clarify the influence of shielding gas used to protect a molten metal during fabrication on the geometric accuracy of the built part obtained via the GMAW-based WAAM process, the influence of the metal transfer behavior on the geometry and surface roughness of the fabricated structures was investigated via visualization using a high-speed camera when single and multilayer depositions were performed under different heat inputs and gases. However, when using Ar gas, the heat flux from an arc to the workpiece is relatively low, limiting the depth of the molten pool during welding. The effect of its characteristics on the stair steps that are inevitably produced on the side face of the multilayer structure in the WAAM process was verified, and for a heat input of 1.17 kJ/cm under Ar gas, a higher geometric accuracy of the multilayer structure was obtained without interlayer cooling. The short circuit between the metal droplet and the fabricated surface, where the molten pool is insufficiently formed, resulted in a hump formation. Further, the metal transfer under Ar gas reduced the surface irregularities on the fabricated structure.

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