Effects of shielding gas composition on arc profile and molten pool dynamics in gas metal arc welding of steels

Wang, L L; Lu, Fenggui; Wang, H P; Murphy, Anthony B.; Tang, Xinhua

doi:10.1088/0022-3727/47/46/465202

Cited by 37 publications

(25 citation statements)

References 41 publications

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“…Além disso, a junta apresenta maiores penetrações e menos porosidade quando se utiliza adições de dióxido de carbono no gás de proteção [12]. Contudo, o aumento da quantidade de CO 2 na mistura pode causar um aumento considerável na corrente de transição e minimizar a condutividade do arco elétrico [13].…”

Section: Introductionunclassified

Influência da composição do gás de proteção nas tensões residuais de juntas de aço DP600 soldadas pelo processo GMAW

et al. 2019

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RESUMO A indústria automobilística vem investindo em novos processos de fabricação que melhoram a produtividade sem perda da qualidade. Entretanto, a presença de tensões residuais, geradas em todos os processos de fabricação, constitui um dos grandes problemas encontrados na indústria metal mecânica, pois estas podem se somar às tensões de carregamento externo e causar falhas catastróficas em equipamentos e componentes. Sendo a soldagem um dos processos de fabricação mais utilizados atualmente, é necessário entender como os parâmetros de soldagem impactam na natureza e magnitude das tensões residuais geradas. Em alguns processos de soldagem são utilizados gases de proteção, que podem influenciar a condutividade do arco elétrico e, consequentemente, afetar o comportamento das tensões residuais nas juntas soldadas. Neste trabalho foi realizado um estudo experimental sobre a influência do percentual de CO2 dos gases de proteção com base em argônio, nas tensões residuais geradas em juntas de aço avançado de alta resistência DP600, soldadas pelo processo GMAW (amplamente utilizado na indústria automobilística). As tensões residuais foram medidas por difração de raios-X, pelo método do sen2ψ. A avaliação microestrutural foi realizada através de microscopia óptica. Os resultados mostraram que as tensões residuais têm natureza trativa, da ordem de 120 MPa, em todas amostras que utilizaram gás de proteção com menor percentual de CO2.

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Section: Introductionunclassified

Influência da composição do gás de proteção nas tensões residuais de juntas de aço DP600 soldadas pelo processo GMAW

et al. 2019

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“…It is significant and essential to produce large area plasma at atmospheric pressure with high stability by arc discharge to accommodate the industrial applications . However, due to the thermal pinch and the self‐induced magnetic compression effect, inhomogeneity is the inherent attribute of the arc discharge plasma. Therefore, many researchers have devoted themselves to investigate generation of large volume and stable arc plasma in the last several decades.…”

Section: Introductionmentioning

confidence: 99%

Dynamic behaviour of alternating current arc discharge in a multi‐arc generator at atmospheric pressure

Lin

Zhao

et al. 2019

Contributions to Plasma Physics

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In this letter, a multi‐arc generator with three high‐voltage electrodes and a common grounded one was developed for the purpose of obtaining large area and steady arc plasma at atmospheric pressure. Three typical discharge states were found in the multi‐arc generator: independent movement of three arc columns, confluence of two arc columns, and confluence of three arc columns. The three discharge states cyclically occur on the evolution of the arc discharge and their duration is influenced by the power dissipation and plasma working gas flow rate. With an increase of discharge power and a decrease of the gas flow rate, the duration of multiple arc confluence increases, which contributes to the suppression of the fluctuation amplitude of each arc. Frequency domain analysis of the arc voltage envelope shows that the frequency of arc fluctuation increases in the multi‐arc mode in the multi‐arc generator compared to that in the single arc mode.

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“…He found that the added oxygen affected the thermo-physical properties of shielding gas mixtures and the surface tension, which finally determined the arc characteristics and the flow pattern of welding pool. Wang et al applied an inhouse simulation model to evaluate the GMAW process shielded by gas mixtures of argon and CO2 [8]. The results indicated that the added CO2 brought about a strong constriction effect on arc.…”

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confidence: 99%

“…The narrow gap groove leads to more concentrated arc energy. The detailed arc profile characteristics such as arc length, arc width and arc area at the peak current for varied contents of CO2 and O2 in shielding gas are displayed in [8]. Therefore, when proper small amount of CO2 or O2 is added into the pure argon, the thermal conductivity of arc gets higher, which results in more uniform heat distribution and expansion of arc.…”

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confidence: 99%

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

Liu

Tang

et al. 2020

Preprint

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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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Effects of shielding gas composition on arc profile and molten pool dynamics in gas metal arc welding of steels

Cited by 37 publications

References 41 publications

Influência da composição do gás de proteção nas tensões residuais de juntas de aço DP600 soldadas pelo processo GMAW

Influência da composição do gás de proteção nas tensões residuais de juntas de aço DP600 soldadas pelo processo GMAW

Dynamic behaviour of alternating current arc discharge in a multi‐arc generator at atmospheric pressure

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

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