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Shielding gas

About: Shielding gas is a research topic. Over the lifetime, 6697 publications have been published within this topic receiving 58668 citations.


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TL;DR: This article examined the thermal processes occurring in moving electrodes for GMAW with the objectives of determining which phenomena are important in controlling the melting rate and explaining the formation of a tapering tip observed for some combinations of electrode materials and shielding gases.
Abstract: The present study examines the thermal processes occurring in moving electrodes for GMAW with the objectives of 1) determining which phenomena are important in controlling the melting rate and 2) explaining the formation of a tapering tip observed for some combinations of electrode materials and shielding gases

21 citations

Journal ArticleDOI
TL;DR: In this article, the authors evaluated the various forces acting on the liquid weld metal when using argon and helium, and their effects are discussed; it was determined that argon produces a greater vertically downward force in the central region than does helium for both the arc force and Lorentz force.
Abstract: The transient variation of the shielding gas present in the alternating shielding gas process produces a dynamic action within the liquid weld metal. Flow vectors opposite in direction have been reported due to the various forces acting on the weld metal when argon and helium are present; however, no data have been provided to substantiate this claim. This part of the study evaluates the various forces acting on the liquid weld metal when using argon and helium, and their effects are discussed. It was determined that argon produces a greater vertically downward force in the central region than does helium for both the arc force and Lorentz force. However, helium produces a greater radially outward force at the pool surface than does argon due to plasma shear stress and Marangoni convection. In addition, the buoyancy force, i.e. the vertically upward force in the central portion of the weld metal, was greater for helium.

21 citations

Journal ArticleDOI
TL;DR: The effect of the uniform velocity on carbon dioxide (CO2) shielding arc welding was examined by laboratory experiments and the ventilation system examined successfully fulfilled the requirement for open-type push-pull ventilators prescribed in Japanese regulations.
Abstract: Recently, open-type push-pull ventilation systems have been widely employed as effective substitutes for the conventional local exhaust ventilation system, and have prevailed at many welding workshops in Japan. In this study, the effect of the uniform velocity on carbon dioxide (CO2) shielding arc welding was examined by laboratory experiments. The ventilation system examined in the experiments successfully fulfilled the requirement for open-type push-pull ventilators prescribed in Japanese regulations (ordinances). It was proved that the velocity at any points in the capture zone fell in the range of 50 to 150% of the average capture zone velocity. Welding defects could be avoided by controlling the flow rate of shielding gas. Unless the capture velocity exceeded a 0.8 m/s, the formation of blow-holes in the welded metal could be prevented at the shielding gas flow rate of 20 L/min. If the flow rate was provided at 30 L/min and 40 L/min, blow-holes didn't form at the capture velocity of 1.2 m/s and 1.6 m/s, respectively. At a capture velocity of faster than 0.3 m/s, the fume concentration at welder's breathing zone was reduced to a level below the limit values: ACGIH (TLV) and Japan Welding Engineering Society (CLV#). These data are important for designing open-type push-pull ventilation in the welding workshop. The other engineering countermeasures currently employed in the welding work in Japan, such as fume collecting torch and general ventilation, are also concerned in this report. #: Control Limit Value

21 citations

Journal ArticleDOI
10 Apr 2012
TL;DR: In this paper, the effects of using alternating shielding gases for aluminum alloy welding were investigated for the Gas Metal Arc Welding (GMAW) process and the results showed that the benefits of using these gases in this manner include increased travel speed, reduced distortion, reduced porosity and marginal improvements in mechanical properties.
Abstract: Studies have been carried out to determine the effects of implementing alternating shielding gases for 6082T6 aluminium alloy welding. Alternating shielding gases is a newly developed method of supplying shielding gases to the weld area to enhance the efficiency of the standard Gas Metal Arc Welding (GMAW) process. This method involves discretely supplying two different shielding gases to the weld zone at a pre-determined frequency which creates a dynamic action in the weld pool. Several benefits have been identified in relation to supplying shielding gases in this manner including increased travel speed, reduced distortion, reduced porosity and, in the case of specific alternating frequencies, marginal improvements in mechanical properties. All in all, this method of shielding gas delivery presents attractive benefits to the manufacturing community, namely the increased productivity and quality in addition to a reduction in the amount of post-weld straightening required. However, the literature available on this advanced joining process is very scant, especially so for aluminium alloys. For this reason, an evaluation has been carried out on the application of alternating shielding gases for the GMAW process on 6082T6 aluminium alloys.

21 citations

01 Jan 2019
TL;DR: In this article, DSS weld microstructures were investigated as a function of weld thermal cycles and shielding gas nitrogen content, and actual gas tungsten arc welding (GTAW) in controlled environments were used to relate to the weld austenite-to-ferrite (A/F) phase ratios.
Abstract: Much development work has been performed worldwide on the welding of duplex stainless steels (DSSs), where losses in base metal nitrogen during welding have been compensated by filler metal and nitrogen additions to the shielding gas. However, some heat-affected zone (HAZ) microstructural changes have not always responded consistently to nitrogen mixtures added to the shielding gas. In this work, DSS weld microstructures were investigated as a function of weld thermal cycles and shielding gas nitrogen content. Physical simulations, actual gas tungsten arc welding (GTAW) in controlled atmospheres, and entrapped nitrogen measurements were used to relate to the weld austenite-to-ferrite (A/F) phase ratios. Results showed the thermal cycles had a stronger effect on the weld A/F ratio than shielding gas nitrogen content. Physical simulations and actual GTAW trials also showed the A/F ratio changes in the opposite way in the fusion zone than in the HAZ. Reheating was also found to have an important effect on the microstructure. The above findings should allow fabricators to better design the welding process with DSS. Better control of nitrogen-containing shielding gas mixtures, along with heat input limitations, should result in more consistent weld properties and wider use of DSS by industry.

21 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202357
2022103
2021107
2020168
2019206
2018206