• Title/Summary/Keyword: GTA

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Effects of Oxygen Contents in Shielding Gas on the Properties of Ferritic Stainless Steel GTA Weld (페라이트계 스테인리스강 GTA 용접부 특성에 미치는 보호가스 중 산소의 영향)

  • Lee, Won-Bae;Uhm, Sang-Ho;Woo, In-Su
    • Journal of Welding and Joining
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    • v.28 no.5
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    • pp.93-98
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    • 2010

  • The properties of GTA weld for ferritic stainless steel have been studied with different $O_2$ contents in Ar shielding gas at the constant welding speed. A small amount of $O_2$ (0.01~1.0%) was mixed in Ar shielding gas in order to improve the weld penetration. The fully penetrated GTA weld was acquired at 160A weld current shielded by pure Ar gas. Addition of oxygen larger than 0.1% made a full penetration at lower weld current than 160A. The small addition of $O_2$ in Ar shielding gas improved the penetration properties of GTA weld because the $O_2$ in the molten pool accelerated the flow of molten pool and changed the flow pattern from outward to inward direction. The impact energy and DBTT (Ductile- Brittle- Transition-Temperature) of the GTA weld shielded by Ar+$O_2$ (less 0.3%) was similar and the corrosion properties of GTA weld was slightly inferior to those of GTA weld shielded by pure Ar gas.

  • https://doi.org/10.5781/KWJS.2010.28.5.093 인용 PDF KSCI

Bead Formation and Wire Temperature Distribution during Ultra-high-speed GTA Welding Using Pulse-heated Hot-wire

  • Shinozaki, K.;Yamamoto, M.;Mitsuhata, Koichi;Nagashima, Toshiharu;Kanazawa, T.;Arashin, H.
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.226-234
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    • 2009

  • The purpose of this study was to investigate the melting phenomenon of filler wire in detail and to obtain the precise temperature distribution of filler wire during GTA welding under the ultra-high welding speed condition in order to develop the ultra-high-speed GTA welding process with the pulse-heated hot-wire system by using three kinds of materials. The melting phenomenon of filler wire was observed using a high-speed camera and the temperature distribution of filler wire was measured using a radiation thermometer. From the above result, the adequate welding conditions of each material to make the GTA welding process with the ultra-high welding speed could be obtained. The ultra-high-speed GTA welding process needed the adequate wire current in order to obtain the adequate temperature distribution and the adequate melting position of filler wire. Moreover, the temperature distributions of three kinds of filler wire could be estimated by using the proposed simple estimation method.

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Porosity Reduction during Gas Tungsten Arc-Gas Metal Arc Hybrid Welding of Zinc Coated Steel Sheets (II) - Hybrid Welding Results (GTA-GMA 하이브리드공정에 따른 자동차용 아연도금강판의 용접부 기공감소 (II) - 하이브리드공정 적용 결과)

  • Ahn, Young-Nam;Kim, Cheolhee
    • Journal of Welding and Joining
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    • v.34 no.4
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    • pp.48-54
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    • 2016

  • The use of Zn coated steel has increased in the automotive industry due to its excellent corrosion resistance. Conventionally the BIW(body-in-white) structure and the hang-on parts have been made of Zn coated steel and more recently Zn coated steel began to be applied in the chassis parts. During gas metal arc (GMA) welding of the chassis part, lap fillet joint used to be adopted but spatter generation and porosities are most important concerns. In the industrial applications, an intentional joint gap was made to avoid the weld defects but it is not easy to control the size of joint gap. In this research, gas tungsten arc (GTA) is combined with GMA welding where GTA precedes GMA. As pulsed arc was adopted as GMA, GTA was oscillated along the longitudinal direction by pulsing GMA, but the arc oscillation did not disturb the molten droplet transfer of GMA welding. By increasing the distance between GTA and GMA, the length of weld pool increased and porosity could be reduced. Moreover porosity in the welds was fully removed when the distance between two arcs was 15 mm.

  • https://doi.org/10.5781/JWJ.2016.34.4.48 인용 PDF KSCI

The Characteristics of Energy Distribution to Arc Length and Hydrogen Mixing in GTA Welding (GTA 용접에서 아크 길이와 수소 혼합에 따른 에너지분포 특성)

  • Oh, Dong-Soo;Baek, Sang-Yeob;Lee, Chil-Soon;Hwang, Dong-Soo;Ham, Hyo-Sik;Park, Kyung-Do;Jung, Yun-Ho;Cho, Sang-Myung
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.30-30
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    • 2009

  • GTA 용접에서 용입, 용접부의 크기와 형상이 형성되는 아크 물리학적 현상을 이해함에 있어서 에너지 분포특성은 매우 중요한 인자이다. GTA 용접에서 아크 길이의 변화와 사용된 실드 가스 종류에 따라 음극인 텅스텐 전극 팁의 아크 루트 직경에 큰 변화를 주며, 양극인 모재 쪽의 에너지 분포에 영향을 미치며 된다. 기존의 연구자들은 저전류나 중전류 영역의 GTA 용접에서 텅스텐 전극의 선단각과 용입 형태와 의 관계를 plasma 기류 등에 의해 고찰하거나, 최대 아크압력에 미치는 전극형상의 영향에 대하여 연구하였다. 용접부에 작용하는 아크 압력의 분포는 결국 운동 에너지의 분포이다. 기존의 연구자들에 비하여 보다 간편한 실험을 통하여 양극 모재위의 아크 압력에 의한 에너지 분포특성을 규명하는 연구가 필요하다. 본 연구의 목적은 GTA 용접의 용접전류 100A~200A 영역에서 아크 길이 변화와 Ar 가스에 $H_2$ 혼합에 따른 측정된 아크 압력으로부터 기존연구자들의 아크 물리학적 결과들을 활용하여 양극 모재 위에 작용하는 전류밀도 분포를 유도하는 것이다. GTA 용접에서 아크 길이의 변화와 Ar 가스에 $H_2$ 혼합은 아크 압력분포에 큰 영향을 미치며, 이에 따라 에너지 분포특성에 많은 영향을 미친다. 아크 길이가 증가함에 따라 Ar가스와 $H_2$ 혼합가스의 에너지 분포는 감소하였고, Ar가스에 $H_2$ 혼합에 의해 아크 에너지가 증가하여 용입형상에 큰 영향을 미칠 것으로 판단된다. 이에 대한 연구는 향후 GTA 용접 응용분야 확대 적용될 것이며, 아크 물리학 연구에 기초적이고 아주 중요한 과학적인 자료가 될 것으로 판단된다.

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