• Title/Summary/Keyword: MIG-welding

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Welder's Exposure to Airborne Hexavalent Chromium and Nickel during Arc Welding in a Shipyard (모 조선업체 아크 용접 작업자의 공기중 6가 크롬 및 니켈 노출에 관한 연구)

  • Shin, Yong Chul;Yi, Gwang Yong;Lee, Na Roo;Oh, Se Min;Kang, Seong Kyu;Moon, Young Hahn;Lee, Ki Ra
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.8 no.2
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    • pp.209-223
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    • 1998

  • The aim of this study was to evaluate welders' exposure to hexavalent chromium (Cr(VI)) and nickel (Ni) during welding operations in a Korean shipyard. The airborne Cr(VI) and Ni concentrations were measured during metal inert gas (MIG) welding on mild and stainless steel, and manual metal arc (MMA) welding on mild steel. The geometric mean (GM) of Cr(VI) concentrations inside the welding helmet during MIG welding on mild steel were $0.0018mg/m^3$ inside a ship section, and $0.0015-0.0026mg/m^3$ at the welding shops. All of the personal breathing zone air samples were below the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value ($TLV^{(R)}$) of $0.01mg/m^3$. Conversely, eighty-eight percent(21 of 24) of the personal breathing zone air samples exceeded the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit of $0.001mg/m^3$. Ni was not detected on 20 of 23 air samples collected during MIG welding on mild steel. The three Ni samples above the limit of detection ranged from 0.015 to $0.044mg/m^3$. The GM of Cr(VI) concentrations during MMA welding on mild steel were $0.0013mg/m^3$, but Ni was not detected in the air samples during this operation. It is assumed that the airborne Cr(VI) and Ni during mild steel welding were derived from the base metals which contained about 0.03% Cr and 0.03% Ni. The GM of airborne total Cr, Cr(VI) and Ni concentrations during MIG welding on stainless steel were 4.02, 0.13 and $0.86mg/m^3$, respectively, and the levels of Cr(VI) and Ni were above the ACGIH-$TLV^{(R)}$. Cr(VI) comprised about 35.5% of the total chromium(Cr) from MIG welding on mild steel, and about 8.4% of total Cr from MIG welding on stainless steel. The ratios of Cr(VI) to total Cr were significantly different among welding shops. It was concluded that welders were exposed to high levels of Cr(VI) and Ni during welding on stainless steel, and were exposed to low levels of Cr(VI) even during welding on mild steel.

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Effects of laser and arc power on the penetration depth in $CO_2$ laser-MIG hybrid welding ($CO_2$ 레이저-MIG 하이브리드 용접부 용입깊이에 미치는 레이저 및 아크 출력의 영향)

  • 홍승갑;이종봉
    • Proceedings of the KWS Conference
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    • 2003.05a
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    • pp.81-83
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    • 2003

  • The potential advantages of the hybrid welding process are improved weld penetration, enhanced gap tolerance, control of weld metal composition, and improved weld quality in comparison to laser or arc welding. Especially, the deep penetration of hybrid welding is very attractive in welding of thick plates. In this study, therefore, the influence of arc power in hybrid welding on detailed bead dimensions at different laser power levels was investigated.

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Study on the Optimization Field Welding Conditions of Low Heat-Input Pluse MIG Welding Process for 5052 Aluminum Alloy Sheets (Al 5052 합금의 저입열 Pulse MIG 최적 현장 용접조건 산정에 관한 실험적 연구)

  • Kim, Jae-Seong;Lee, Young-Gi;An, Ju-Sun;Lee, Bo-Young
    • Journal of Welding and Joining
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    • v.29 no.1
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    • pp.80-84
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    • 2011

  • The weight reduction of the transportations has become an important technical subject Al and Al alloys, especially Al 5052 alloys have been being applied as door materials for automobile. One of the most widely known car weight-reduction methods is to use light and corrosion-resistant aluminum alloys. However, because of high electrical and thermal conductivity and a low melting point, it is difficult to obtain good weld quality when working with the aluminum alloys. Also, Pulse MIG welding is the typical aluminum welding process, but it is difficult to apply to the thin plate, because of melt-through and humping-bead. In order to enhance weld quality, welding parameters should be considered in optimizing the welding process. In this experiment, Al 5052 sheets were used as specimens, and these materials were welded by adopting new Cold Metal Transfer (CMT) pulse process. The proper welding conditions such as welding current, welding speed, torch angle $50^{\circ}$ and gap 0~1mm are determined by tensile test and bead shape. Through this study, range of welding current are confirmed from 100A to 120A. And, the range of welding speed is confirmed from 1.2m/min to 1.5m/min.

  • https://doi.org/10.5781/KWJS.2011.29.1.080 인용 PDF KSCI