scholarly journals The effect of metal transfer modes and shielding gas composition on the emission of ultrafine particles in MAG steel welding

2014 ◽  
Vol 19 (2) ◽  
pp. 168-176 ◽  
Author(s):  
J. F. Gomes ◽  
R. M. Miranda ◽  
P.A. Carvalho ◽  
M. L. Quintino
Keyword(s):  
Surface Area ◽  
Ultrafine Particles ◽  
Formation Rate ◽  
Welding Process ◽  
Gas Mixtures ◽  
Metal Transfer ◽  
Current Intensity ◽  
Welding Parameters ◽  
Gas Composition ◽  
Shielding Gas

The present study aims to characterize ultrafine particles emitted during gas metal arc welding of mild steel and stainless steel, using different shielding gas mixtures, and to evaluate the effect of metal transfer modes, controlled by both processing parameters and shielding gas composition, on the quantity and morphology of the ultrafine particles. It was found that the amount of emitted ultrafine particles (measured by particle number and alveolar deposited surface area) are clearly dependent from the main welding parameters, namely the current intensity and the heat input of the welding process. The emission of airborne ultrafine particles increases with the current intensity as fume formation rate does. When comparing the shielding gas mixtures, higher emissions were observed for more oxidizing mixtures, that is, with higher CO2content, which means that these mixtures originate higher concentrations of ultrafine particles (as measured by number of particles by cubic centimeter of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more hazardous condition regarding welders exposure.

Effects of Wire Rotating Frequency on Metal Transfer Process in Rotating Arc Narrow Gap Horizontal GMAW

2011 ◽  
Vol 189-193 ◽  
pp. 3395-3399 ◽  
Author(s):  
Ning Guo ◽  
Yan Fei Han ◽  
Chuan Bao Jia ◽  
Yong Peng Du
Keyword(s):  
Transfer Process ◽  
High Speed ◽  
Stable Process ◽  
Welding Process ◽  
Metal Transfer ◽  
Welding Parameters ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Weld Formation ◽  
Rotating Arc

The metal transfer process with different welding parameters in rotating arc narrow gap horizontal welding is successfully observed by the high-speed photography system. The effects of wire rotating frequency on metal transfer process in rotating arc narrow gap horizontal welding are novelly explored. The metal transfer with different wire rotating frequency presents different modes. The results indicate that the droplet transfer has stable process with the rotating frequency of 5-20 Hz. And the weld formation is quite shapely. But with the high rotating frequency of 50 Hz, the metal transfer process is not acceptable and the weld formation is very pool. Metal transfer process is one of the most important factors of effecting the weld formation in rotating arc horizontal welding process besides the molten pool behavior and welding thermal circles.

scholarly journals Influence of Welding Parameters and Shielding Gas Composition on GTA Weld Shape

2005 ◽  
Vol 45 (1) ◽  
pp. 66-70 ◽  
Author(s):  
Shanping LU ◽  
Hidetoshi FUJII ◽  
Kiyoshi NOGI
Keyword(s):  
Welding Parameters ◽  
Gas Composition ◽  
Shielding Gas ◽  
Weld Shape

scholarly journals Optimization of TIG Welding Parameters for the 202 Stainless Steel Using NSGA-II

2020 ◽  
Vol 8 (4) ◽  
Author(s):  
Neeraj Sharma ◽  
◽  
Wathiq Sleam Abduallah ◽  
Manish Garg ◽  
Rahul Dev Gupta ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Flow Rate ◽  
Gas Flow ◽  
Welding Process ◽  
Welding Current ◽  
Welding Parameters ◽  
Shielding Gas ◽  
Gas Flow Rate ◽  
Electrode Diameter ◽  
Weld Region

Tungsten Inert Gas welding is a fusion welding process having very wide industrial applicability. In the present study, an attempt has been made to optimize the input process variables (electrode diameter, shielding gas, gas flow rate, welding current, and groove angle) that affect the output responses, i.e., hardness and tensile strength at weld center of the weld metal SS202. The hardness is measured using Vicker hardness method; however, tensile strength is evaluated by performing tensile test on welded specimens. Taguchi based design of experiments was used for experimental planning, and the results were studied using analysis of variance. The results show that, for tensile strength of the welded specimens, welding current and electrode diameter are the two most significant factors with P values of 0.002 and 0.030 for mean analysis, whereas higher tensile strength was observed when the electrode diameter used was 1.5 mm, shielding gas used was helium, gas flow rate was 15 L/min, welding current was 240A, and a groove angle of 60o was used. Welding current was found to be the most significant factor with a P value of 0.009 leading to a change in hardness at weld region. The hardness at weld region tends to decrease significantly with the increase in welding current from 160-240A. The different shielding gases and groove angle do not show any significant effect on tensile strength and hardness at weld center. These response variables were evaluated at 95% confidence interval, and the confirmation test was performed on suggested optimal process variable. The obtained results were compared with estimated mean value, which were lying within ±5%.

Effect of N2 Addition on Microstructure and Properties of SAF 2507 Duplex Stainless Steels GTAW Welded Joint

2012 ◽  
Vol 724 ◽  
pp. 127-130
Author(s):  
Dong Fang Du ◽  
Jie Liu ◽  
Guo Ping Li ◽  
Jin Ming Liu
Keyword(s):  
Weld Metal ◽  
Impact Energy ◽  
Welded Joint ◽  
Welding Process ◽  
Welding Parameters ◽  
Shielding Gas ◽  
Micro Hardness ◽  
Weld Metals ◽  
Welding Arc ◽  
The Impact

In this paper, SAF2507 duplex stainless steel (DSS) was welded by GTAW with ER2594 as filler wire, and Ar + N2 as shielding gas. The results show that, with increasing the content of N2 in the shielding gas, the amount of austenite in weld metal increase, the micro-hardness drops and impact energy increases; the use of Ar +2 ~ 3% N2 welding parameters, the microstructure and mechanical properties of welded joints are the best, the austenitic rates and impact energy of weld metals are 51%~53% and 75~88 J, respectively, and the welding process is easy to control; when the content of N2 reach 5%, the impact energy of weld metal decreases obviously and the welding arc is unstable.

Effect of Gas Metal Arc Welding Parameters on Mechanical Properties for Carbon Steel ASTM A285 Grade A

2011 ◽  
Vol 341-342 ◽  
pp. 16-20
Author(s):  
Mongkol Chaisri ◽  
Prachya Peasura
Keyword(s):  
Carbon Dioxide ◽  
Tensile Strength ◽  
Carbon Steel ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Welding Parameters ◽  
Shielding Gas ◽  
Metal Arc Welding ◽  
Arc Welding Process

The research was study the effect of gas metal arc welding process parameters on mechanical property. The specimen was carbon steel ASTM A285 grade A which thickness of 6 mm. The experiments with full factorial design. The factors used in this study are shielding gas and voltage. The welded specimens were tested by tensile strength testing and hardness testing according to ASME boiler and pressure vessel code section IX 2007. The result showed that both of shielding gas and voltage had interaction on tensile strength and hardness at 95% confidential (P value < 0.05). Factors affecting the tensile strength are the most carbon dioxide and 27 voltage were tensile strength 213.43 MPa. And hardness maximum of 170.60 HV can be used carbon dioxide and 24 voltage. This research can be used as data in the following appropriate parameters to gas metal arc welding process.

scholarly journals Silicate Island Formation in Gas Metal Arc Welding

2021 ◽  
Vol 100 (01) ◽  
pp. 13-26
Author(s):  
RICHARD DERRIEN ◽  
◽  
ETHAN MICHAEL SULLIVAN ◽  
STEPHEN LIU ◽  
ELODIE MOINE ◽  
...  
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Formation Rate ◽  
Welding Process ◽  
Electromagnetic Levitation ◽  
Welding Parameters ◽  
Silicate Formation ◽  
Metal Arc Welding ◽  
Initial Melting

Because formation of silicate islands during gas metal arc welding is undesirable due to decreased productivity and decreased quality of welds, it is important to understand the mechanism of the formation of these silicate islands to mitigate their presence in the weld. The effects of welding parameters on the silicate formation rate were studied. Results showed that the applied voltage and oxidizing potential of the shielding gas were the parameters that most strongly influenced the amount of silicates formed on the surface of the weld bead. High-speed video was used to observe the formation of silicate islands during the welding process, which showed that the silicates were present at each stage of the welding process, including the initial melting of the wire electrode, and grew by coalescence. A flow pattern of the silicate islands was also proposed based on video analysis. An electromagnetic levitation system was used to study the growth kinetics of the silicate islands. Silicate coverage rate was found to increase with increasing oxidizing time, increasing oxidizing potential of the atmosphere, and increasing content of alloying elements except for Ti.

scholarly journals Effects of active gases on droplet transfer and weld morphology in pulsed-current NG-GMAW of mild steel

2020 ◽  
Author(s):  
Guoqiang Liu ◽  
Xinhua Tang ◽  
Qi Xu ◽  
Fenggui Lu ◽  
Haichao Cui
Keyword(s):  
Mild Steel ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Metal Transfer ◽  
Pulsed Current ◽  
Shielding Gas ◽  
Droplet Transfer ◽  
Spray Transfer ◽  
Pure Argon

Abstract Small amount of active gases CO 2 and O 2 were added into pure argon inert shielding gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel. Their effects on droplet transfer and arc behavior were investigated. A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology. When the proportion of CO 2 , being added into the pure argon shielding gas, changes from 5% to 5%, the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer, while it remains the pulsed spray streaming transfer when 2% to 10% O 2 is added. Both CO 2 and O 2 are favorable to stabilizing arc and welding process. O 2 is even more effective than CO 2 . However, O 2 is more likely to cause the inclusion defects in the weld, while CO 2 can improve the weld appearance in some sense. The weld surface concavity, which is sensitive to the formation of lack-of-fusion defect in NG-GMAW, is greatly influenced by the addition of active gas, but the weld width and weld penetration almost keep constant.

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