scholarly journals Underwater Pulse-Current FCAW - Part 1: Waveform and Process Features

2020 ◽  
Vol 99 (05) ◽  
pp. 135s-145s ◽  
Author(s):  
CHUANBAO JIA ◽  
◽  
JUNFEI WU ◽  
YANFEI HAN ◽  
YONG ZHANG ◽  
...  
Keyword(s):  
Pulse Current ◽  
Short Circuit ◽  
Droplet Diameter ◽  
Low Frequency ◽  
Welding Process ◽  
Welding Current ◽  
Experimental System ◽  
Flux Cored Arc Welding ◽  
The Stability ◽  
Repulsive Forces

The typical metal transfer mode in conventional underwater wet flux cored arc welding (FCAW) delivers large droplet repulsive transfer with low frequency. The process stability and the weld quality are seriously deteriorated with significant spatter and frequent arc extinctions. It is thought the repulsive forces applied on droplets can be reduced by rapidly decreasing the welding current, making the droplets sag and oscillate. A novel underwater pulsecurrent FCAW was proposed to periodically regulate the forces applied on droplets. The experimental system was developed with specially designed pulse current and reliable arc length control. Visual and electrical signals were collected simultaneously to study the process features. It was found that the maximum droplet diameter decreased to less than 5 mm; the temporary arc-extinguishing frequency decreased significantly; there was almost no short-circuit transfer and surface-tension transfer; and the stability of the welding process was significantly improved.

Acoustic Information Acquisition and Time Domain Analysis on Alternating Current Rail Flash Butt Welding

2012 ◽  
Vol 239-240 ◽  
pp. 16-20
Author(s):  
Qi Bing Lv ◽  
Ke Li Tan ◽  
Xi Zhang ◽  
Jian Chen ◽  
Guo Qing Liu
Keyword(s):  
Time Domain ◽  
Acoustic Signal ◽  
Information Acquisition ◽  
Welding Process ◽  
Welding Current ◽  
Time Domain Analysis ◽  
Mean Square ◽  
Butt Welding ◽  
The Mean ◽  
The Stability

Based on the mobile rail flash butt welding machine UN5-150ZB, the synchronous data acquisition hardware system was designed to collect welding current, welding voltage and flash acoustic signal in welding process, and the software platform with the functions of signal collecting, waveform display and data operation was developed by higher-level programming language LabVIEW. After the welding current, welding voltage and flash acoustic signal in welding process had been collected, the mean, variance and mean square value of flash acoustic signal in time-domain were analyzed. Through comparison, the relationship between these characteristics and the stability of flash was analyzed. The result shows that the changes of mean and variance of flash acoustic signal are not obvious, and do not correlate with stability of flash, but the mean square value in time domain is closely associated with the stability of flash, and the stability of flash can be indicated by the mean square value.

The Impact of Adscititious Longitudinal Magnetic Field on CO2 Welding Process

2012 ◽  
Vol 538-541 ◽  
pp. 1447-1450 ◽  
Author(s):  
Shu Yuan Jiang ◽  
Xiao Wei Wang ◽  
Huan Ming Chen ◽  
Pin Liu
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Longitudinal Magnetic Field ◽  
Short Circuit ◽  
Welding Process ◽  
Welding Current ◽  
High Speed Photography ◽  
Current Decay ◽  
Co2 Welding ◽  
The Impact

Aiming at the welding arc can act with the magnetic field, has electrical quasi-neutral and electrical conductivity. This paper introduced an adscititious longitudinal magnetic field to control the CO2 welding process and used the Hanover Welding Quality Analyzer to acquire the real-time welding signal. Meanwhile, the short circuit behavior of CO2 welding under the adscititious longitudinal magnetic field, was monitored with the High-speed Photography System. The results show that when the excitation current in an optimal range, the welding current decay and the frequency of short circuit transition is uniform and faster, smaller droplet size and the welding process is more stability than welding without adscititious magnetic field.

Evaluation of the sound signal based on the welding current in the gas—metal arc welding process

2003 ◽  
Vol 217 (5) ◽  
pp. 483-494 ◽  
Author(s):  
M Čudina ◽  
J Prezelj
Keyword(s):  
Arc Welding ◽  
Short Circuit ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Welding Current ◽  
Sound Signal ◽  
Frequency Noise ◽  
Metal Arc Welding ◽  
Arc Welding Process ◽  
Good Agreement

In this paper sound generated during the gas-metal arc welding process in the short-circuit mode was studied. Theoretical and experimental analyses of the acoustic signals have shown that there are two main noise-generating mechanisms. The first mechanism generating characteristic sound impulses is arc extinction and arc ignition; the second noise-generating mechanism is the arc itself, which acts as an ionization sound source and produces mainly high-frequency noise of a low level. The sound signal is used for assessing and monitoring the welding process and for prediction of welding process stability and quality. A new algorithm based on the measured welding current was established for the calculation of emitted sound during the welding process. The algorithm was verified for different supply voltages and for different welding materials. The comparisons have shown that the calculated values are in good agreement with measured values of the sound signal.

scholarly journals Underwater Pulse-Current FCAW - Part 2: Bubble Behaviors and Waveform Optimization

2020 ◽  
Vol 99 (12) ◽  
pp. 303s-311s
Author(s):  
JUNFEI WU ◽  
◽  
YANFEI HAN ◽  
CHUANBAO JIA ◽  
QINGYUAN YANG ◽  
...  
Keyword(s):  
Gas Flow ◽  
Pulse Current ◽  
Droplet Diameter ◽  
Welding Process ◽  
Metal Transfer ◽  
The Novel ◽  
Large Droplet ◽  
Waveform Optimization ◽  
Novel Technology ◽  
The Impact

Underwater pulse-current wet welding was proposed in part 1 of this two-part report. The novel technology obtained improved metal transfer and welding process stability. The main reason for droplet oversizing and long transfer cycles was found to be the deviated large droplet stage. In this part, the waveform optimization for both bubble behaviors and metal transfer were investigated. Efforts were made for shortening the duration of the deviated large droplet stage. Pulse current influences on bubble evolution was studied. It was found that two different separation modes can be adjusted by appropriately changing the current values when the bubbles are necking. Quickly reducing the welding cur-rent can sharply lower the impact force on the droplets due to intense gas flow changes inside. Under the optimized pulse current, the range of the metal transfer cycle became narrower, and droplet diameters were smaller than that of the original condition. Stable and improved metal transfer processes were achieved with a frequency of 7.52 Hz and an average droplet diameter of 2.4 mm, which was about 1.5 times the wire diameter. The optimized pulse waveform greatly improved weld formation with less spatter and a more uniform appearance.

scholarly journals Real-Time Weld Gap Monitoring and Quality Control Algorithm during Weaving Flux-Cored Arc Welding Using Deep Learning

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1135
Author(s):  
Chengnan Jin ◽  
Sehun Rhee
Keyword(s):  
Arc Welding ◽  
Control Algorithm ◽  
Weld Seam ◽  
Welding Process ◽  
Welding Current ◽  
Forming Process ◽  
Flux Cored Arc Welding ◽  
Arc Welding Process ◽  
Shell Forming ◽  
The Time Domain

In the flux-cored arc welding process, which is most widely used in shipbuilding, a constant external weld bead shape is an important factor in determining proper weld quality; however, the size of the weld gap is generally not constant, owing to errors generated during the shell forming process; moreover, a constant external bead shape for the welding joint is difficult to obtain when the weld gap changes. Therefore, this paper presents a method for monitoring the weld gap and controlling the weld deposition rate based on a deep neural network (DNN) for the automation of the hull block welding process. Welding experiments were performed with a welding robot synchronized with the welding machine, and the welding quality was classified according to the experimental results. Welding current and voltage signals, as the robot passed through the weld seam, were measured using a trigger device and analyzed in the time domain and frequency domain, respectively. From the analyzed data, 24 feature variables were extracted and used as input for the proposed DNN model. Consequently, the offline and online performance verification results for new experimental data using the proposed DNN model were 93% and 85%, respectively.

Modelling and analysis of delta ferrite content in claddings deposited by flux cored arc welding using a neural network

2009 ◽  
Vol 223 (4) ◽  
pp. 779-787 ◽  
Author(s):  
P K Palani ◽  
N Murugan
Keyword(s):  
Neural Network ◽  
Arc Welding ◽  
Welding Process ◽  
Welding Current ◽  
Ferrite Content ◽  
Delta Ferrite ◽  
Novel Approach ◽  
Flux Cored Arc Welding ◽  
Minimum Number ◽  
Arc Welding Process

Measurement of delta ferrite in cladding gives important insight into the future mechanical and corrosion resistant behaviour of the cladded structures. The amount of delta ferrite formed during cladding is influenced by process parameters such as welding speed, welding current, and nozzle-to-plate distance. Therefore, it is essential to predict the effect of these parameters on the formation of delta ferrite. This article discusses the development of an artificial neural network model to predict the delta ferrite content in austenitic stainless-steel claddings deposited by the flux cored arc welding process. A novel approach of using the design of experiments to collect data to train the network has been adopted in this investigation. The study revealed that the delta ferrite content can be predicted more accurately using the neural networks with a minimum number of experiments. The results also indicated that welding current and speed have a significant influence on the amount of ferrite and the interaction effects of these parameters play a major role in determining ferrite in the claddings.

Diffusible Hydrogen Control in Flux Cored Arc Welding Process

2013 ◽  
Vol 597 ◽  
pp. 171-178 ◽  
Author(s):  
Dariusz Fydrych ◽  
Aleksandra Świerczyńska ◽  
Jacek Tomków
Keyword(s):  
Welding Process ◽  
Welding Current ◽  
Welding Parameters ◽  
Hydrogen Degradation ◽  
Diffusible Hydrogen ◽  
Cored Wire ◽  
Flux Cored Arc Welding ◽  
Deposited Metal ◽  
Relevant Variables ◽  
Arc Welding Process

One of the types of hydrogen degradation of steel welded joints is cold cracking. The direct cause of the formation of cold cracks is simultaneous presence of hydrogen, residual stresses and brittle structure. The way of preventing the occurring of degradation is to eliminate at least one of these factors. Practice has shown that the best solution is to control the amount of hydrogen in deposited metal. In this paper an experimental evaluation of the effect of the welding parameters on the content of diffusible hydrogen in deposited metal obtained from rutile flux cored wire grade H10 was carried out. The state of the art of considered issues was described and results of preliminary investigations were presented. Five factors were considered: the flow rate of shielding gas, the welding current, the arc voltage, the welding speed and the electrode extension. All factors were optimized using a Plackett-Burman design to get the most relevant variables. The level of diffusible hydrogen was determined by a glycerin test. The results of the experiment indicate that appropriate choice of welding parameters may significantly reduce diffusible hydrogen content in deposited metal.

scholarly journals Robust regression analysis for the relationship between welding parameters and microhardness of 410 NiMo martensitic steel deposits on SAE 1020 steel

2020 ◽  
Vol 43 ◽  
pp. e49807
Author(s):  
João Roberto Sartori Moreno ◽  
Celso Alves Corrêa ◽  
Elisangela Aparecida da Silva Lizzi ◽  
Émillyn Ferreira Trevisani Olivio ◽  
Paulo Sergio Olivio Filho ◽  
...  
Keyword(s):  
Welding Speed ◽  
Robust Regression ◽  
Martensitic Steel ◽  
Steel Substrate ◽  
Short Circuit ◽  
Welding Process ◽  
Welding Parameters ◽  
Pulsation Frequency ◽  
Flux Cored Arc Welding ◽  
Average Current

The objective of this study was to analyze the flux-cored arc welding (FCAW) welding parameters and microhardness levels on surface quality of 410 NiMo martensitic stainless-steel coatings. The parameters of the FCAW process applied to the coating, included pulsation frequency, voltage, welding speed, average current and contact tip to work distance. The welding was carried out by the pulsed tubular wire process with pulsed current, constant voltage, Ar+2% O2 shielding gas and short-circuit metal transfer for the deposition of EC410 NiMo Martensitic Steel Deposits alloy coatings on a SAE 1020 steel substrate. For the statistical analysis, the Taguchi experimental planning was applied to test the influence of the parameters of the FCAW process (average current, CTWD, pulsation current and welding speed) on the coating properties. The best configuration with respect to the increased microhardness of the fusion zone in the coating welding process is: Average Current 200 A; CTWD 40 mm; Pulsation Frequency 26.31 Hz and Welding Speed 300 mm min.-1. The lowest microhardness of the melting zone in the coating welding process is: Average Current 170 A; CTWD 30 mm; Pulsation Frequency 23.26 Hz and Welding Speed 400 mm min.-1.

scholarly journals Features of Filler Wire Melting and Transferring in Wire-Arc Additive Manufacturing of Metal Workpieces

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5077
Author(s):  
Artem Voropaev ◽  
Rudolf Korsmik ◽  
Igor Tsibulsky
Keyword(s):  
Additive Manufacturing ◽  
Short Circuit ◽  
Unit Length ◽  
Welding Current ◽  
Travel Speed ◽  
Welding Torch ◽  
Specialized Equipment ◽  
Short Circuits ◽  
The Stability ◽  
Wire Arc Additive Manufacturing

In this paper, we present the results of a study on droplet transferring with arc space short circuits during wire-arc additive manufacturing (WAAM GMAW). Experiments were conducted on cladding of single beads with variable welding current and voltage parameters. The obtained oscillograms and video recordings were analyzed in order to compare the time parameters of short circuit and arc burning, the average process peak current, as well as the droplets size. Following the experiments conducted, 2.5D objects were built-up to determine the influence of electrode stickout and welding torch travel speed to identify the droplet transferring and formation features. Moreover, the current–voltage characteristics of the arc were investigated with varying WAAM parameters. Process parameters have been determined that make it possible to increase the stability of the formation of the built-up walls, without the use of specialized equipment for forced droplet transfer. In the course of the research, the following conclusions were established: the most stable drop transfer occurs at an arc length of 1.1–1.2 mm, reverse polarity provides the best drop formation result, the stickout of the electrode wire affects the drop transfer process and the quality of the deposited layers. The dependence of the formation of beads on the number of short circuits per unit length is noted.

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