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Kobayashi, Minoru; Maki, Shingo; Hashimoto, Yoshizou; Suga, Tetsuo

doi:10.2207/qjjws1943.49.454

Cited by 13 publications

(9 citation statements)

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“…A decrease in arc stability would likely lead to larger droplets with longer dwell times (detachment time) increasing the exposure of the droplet forming at the end of the electrode to the hot arc zone and consequently generating more fume. 8) Rhee and Kanateyasibu 27) discovered that droplet size increased as the percentage of CO 2 in argon shielding gas increased over a range of currents (242-342 A). As noted earlier, an increase in droplet size and consequently, an increase in droplet surface temperature and exposure to the arc, would enhance fume formation.…”

Section: (2)mentioning

confidence: 99%

“…3,4) The chemical composition and the fume formation rate (FFR) depends on several factors, namely, the welding parameters and processes, the filler and base materials and the shielding gas. [5][6][7] Due to the high temperatures involved with the welding arc, metal vapours are thought to predominately originate from the molten tip of the welding electrode, 8) though the molten weld pool is also a significant source. 1,6) Critical factors controlling the FFR/are, arc temperature, surface area of the wire tip and the size of droplets exposed to the arc hot zone.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Fume Formation Rate and Fume Particle Composition for Gas Metal Arc Welding (GMAW) of Plain Carbon Steel Using Different Shielding Gas Compositions

Carpenter¹,

Monaghan

Norrish

2009

ISIJ Int.

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Fig. 4. FFR plotted as a function of %CO 2 in shielding gas for Ar-CO 2 and Ar-CO 2 -2%O 2 .ity of Mn in Fe 3 O 4 (Cubic-(Fe,Mn) 3 O 4 ss).The measured levels of Si in the fume are mostly below the detection capabilities of XRD so it is difficult to determine if Si was present in the form of a siliceous compound, such as SiO 2 or if Si was incorporated into the (Fe,Mn) 3 O 4 structure. The Si atom is also similar in size to the Fe atom but has a higher valence of 4ϩ, therefore according to the Hume-Rothery rules for solubility only partial solubility would be expected.29) The uniform, crystalline nature of the fume particles ( Fig. 1) and the detection of Mn and Si in all particles suggest that fume particles were (Fe,Mn) 3 O 4 with trace Si additions.TEM-EDS results showed no discernable trend in particle composition as a function of shielding gas composition signifying that shielding gas has no apparent effect on particle composition. A small variation of fume composition with particle size may be the source of the observed scatter in the results. 23) ConclusionsThis paper studied the influence of shielding gas composition on FFR and particle composition for robotic GMAW of mild steel. Fume collection tests showed that FFR was strongly affected by increasing CO 2 additions for both binary and ternary Ar-CO 2 -O 2 mixtures. The addition of 2 % O 2 to binary Ar-CO 2 mixtures had no effect on FFR. This was attributed to the fixed voltage welding conditions negating any influence of the addition of 2 % O 2 to the binary Ar-CO 2 mixtures to the FFR. When the O 2 was increased in the ternary mixtures, the FFR increased at the 5% CO 2 level but no discernable increase was observed for the 12 % CO 2 mixtures. Increasing He or CO 2 in ternary Ar-He-CO 2 mixtures had little impact on the FFR.The results obtained have shown that oxygen index only weakly correlates with FFR. A strong correlation of increasing FFR with increasing CO 2 concentrations in argon based shielding gases was obtained. This was attributed to the influence of CO 2 on metal transfer and arc characteristics (decreasing arc stability), where increased CO 2 content would promote larger droplets, longer detachment times, higher arc temperatures and consequently, increased fume generation.The combination of TEM-EDS with XRD identified fume particles as (Fe,Mn) 3 O 4 with trace additions of Si. It was found that shielding gas composition had no obvious effect on fume composition. However, enrichment of Mn in the fume composition was observed. AcknowledgementThe funding for this project was provided by Linde-BOC Gases, Australia. 28)

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Section: (2)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of Fume Formation Rate and Fume Particle Composition for Gas Metal Arc Welding (GMAW) of Plain Carbon Steel Using Different Shielding Gas Compositions

Carpenter¹,

Monaghan

Norrish

2009

ISIJ Int.

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“…Due to the high temperatures involved with the welding arc, metal vapours are thought to predominately originate from the molten top of the welding electrode, 8) though the molten weld pool is also a significant source. 1,6) Metal vapours are readily oxidised, rapidly condensing into nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Influence of Shielding Gas on Fume Size Morphology and Particle Composition for Gas Metal Arc Welding

2008

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Shielding gas is an important parameter in Gas Metal Arc Welding (GMAW). Nevertheless, the influence of shielding gas on particle composition and size distribution of welding aerosols is not clearly understood. Increasing the O 2 or CO 2 content of Ar-based shielding gases resulted in an increase in the average particle size. For binary and ternary Ar, CO 2 , O 2 mixtures, increasing CO 2 had a greater impact than raising O 2 on particle size. Variations in Ar-He-CO 2 mixtures had the least influence. For 100 % CO 2 , the particle size distribution was altered significantly due to the change of the weld transfer mode to globular and particle size coarsened with increasing arc voltage. Shielding gas composition had no observable influence on particle composition and only a slight variation of composition with particle size was observed. Particles were identified as (Fe,Mn) 3 O 4 with trace additions of Si.KEY WORDS: shielding gas; fume; GMAW; particle size, TEM.reported to have 50 % efficiency. Work by Zimmer 9,16,17) used an electrostatic classifier, scanning mobility particle sizer (SMPS), with a condensation particle counter (CPC) that was configured to measure particles down to 4.53 nm. When collecting a representative sample using sampling tubes, potential problems include; preferential withdrawal of particles with respect to size and deposition of particles inside the tube.12) Electrostatic classifiers establish a charge on entering particles, which are then separated according to their electrical mobility. Zimmer and Biswas 17) found that particle counting efficiency decreased with decreasing particle size. This was attributed to smaller particles being scavenged by larger particles.In this study welding fume particle size distributions were determined using TEM and an image analysis technique. This technique is capable of distinguishing agglomerated particles and accurately counting fume particles down to 3-4 nm in size. Experimental ProceduresGMAW was carried out with a Cigweld Trans Robot WS-0550 linked to a Fronius Trans Synergic 4000 power supply and wire feed system. The welding parameters, nominal chemical composition of the base plate, welding wire and shielding gases are listed in Table 1. Welding was generally carried out in spray transfer mode although this changed to globular mode when using 100% CO 2 gas. For 100 % CO 2 , three voltages were used, 32 V, 34 V and 36 V, to investigate the effect of increasing arc voltage on particle size.A WITT KM 30-4 gas mixer was used to generate the shielding gas mixtures listed in Table 1. A Platon flowmeter was placed between the gas mixer and welding machine to ensure a constant flow-rate. The flow meter was calibrated with air using a water displacement test, where the flow rate was calculated by measuring the time taken for a given volume of water to be displaced by the gas. The flow meter reading was then adjusted for the selected gas composition using gas density corrections and Eq. Where F gas is the flow rate of the selected gas, F air is the flow...

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“…Few investigations mainly focused on an indirectly method according to the weight concentration. [2][3][4][5] In the present work, a direct and real time observation of the welding aerosol evolvement is proposed using a differential mobility particle sizer (DMPS) technique, which can obtain not only the aerosol variation during welding, but also the changes with time after welding. It provides a possibility to realise the aerosol dynamics.…”

Section: Introductionmentioning

confidence: 99%

On dynamic characteristics of welding aerosol from fluorite electrodes

Yang¹,

Pan²

2007

Science and Technology of Welding and Joining

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The dynamic variation of welding aerosol particular size from fluorite electrodes during welding and post-welding states was examined on real time using a differential mobility particle sizer (DMPS) process. It was confirmed that the welding aerosols were unstable. In order to directly use the Smoluchowski cohesion equation, an equivalent cohesion coefficient K was introduced for describing the cohesion characteristics of the aerosols.

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Cited by 13 publications

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Analysis of Fume Formation Rate and Fume Particle Composition for Gas Metal Arc Welding (GMAW) of Plain Carbon Steel Using Different Shielding Gas Compositions

Analysis of Fume Formation Rate and Fume Particle Composition for Gas Metal Arc Welding (GMAW) of Plain Carbon Steel Using Different Shielding Gas Compositions

Influence of Shielding Gas on Fume Size Morphology and Particle Composition for Gas Metal Arc Welding

On dynamic characteristics of welding aerosol from fluorite electrodes

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