Zircaloy-4의 플라즈마 아크용접에서 용접변수가 비이드형상에 미치는 영향

고진현,김수성,이영호 대한용접접합학회 1997 대한용접·접합학회지 Vol.15 No.6

A study was undertaken to determine the influence of welding variables such as shielding and plasma gases, torch standoff, travel speed and heat input, etc. on the quality of plasma arc welds in Zircaloy-4 sheet, 2mm thick. Effect of shielding gases and their flow rates on the mechanical properties of Zircaloy-4 welds by plasma arc welding were determined in terms of tensile, bardness and bend tests. The microstructure and fracture surface of Zircaloy-4 welds were investigated by optical and scanning electron microscopies. In addition, the causes of porosity and undercut in plasma arc welds of Zircaloy-4 were also investigated. Zircaloy-4 weld bead width and depth by helium shielding gas showed a wider and deeper than those by argon. It was found that Zircaloy-4 welds with shielding gas of helium did dxhibit a little smoother and uniform weld beads than those with shielding gas of argon. It was also found that the optimum gas flow rates for Zircaloy-4 welding were 0.45l/min for plasma gas with Ar and 4.5 - 6 l/min for shielding gas with He. In addition, there was no big difference in the microstructure and fracture surface of the weld metals made by either Ar shielding gas or He shielding gas.

아르곤 가스를 효율적으로 사용하기 위한 GMA 용접 토치 구조 Part 1 : AMAG와 DMAG 토치가 아르곤 조성에 미치는 영향

최상균,문명철,유중돈 대한용접접합학회 1999 대한용접·접합학회지 Vol.17 No.6

Shielding gas has significant effects on arc stability, metal transfer and weld quality in the gas metal arc welding (GMAW) process. The double gas-shielded MAG(DMAG) and auxiliary gas-shielded MAG (AMAG) torches are investigated for their capability to provide argon-rich gas mixture using small amount of argon gas through the inner and auxiliary nozzles, respectively. Argon composition with the DMAG torch is calculated numerically, and compared with the measured data using the gas chromatogrphy. Gas flow pattern of the DMAG torch is calculated to change from the laminar to turbulent flow when total gas flow rate becomes larger than 4.5 liter/min at room temperature. While argon-rich shielding gas was obtained using both the AMAG and DMAG torches, the AMAG torch provides higher argon composition than the DMAG torch, which demonstrates that argon gas can be utilized more efficiently with the AMAG torch.

Investigation of Effects of Shield Gas on Counterflow Flame Structure

Park, Woe-Chul 한국산업안전학회 2002 한국안전학회지 Vol.17 No.2

메탄-공기의 비예혼합 대향류 확산화염 차폐가스가 화염구조에 미치는 영향을 수치적으로 조사하였다. 20s^+의 저변형율, 메탄가스 19%와 질소 79%의 혼합가스 연료와 공기의 확산화염을 대상으로 하였다. 질소차폐가스의 속도와 차폐가스의 유무에 따른 화염의 형태와 중심선상의 온도 및 축방향 속도의 분포를 비교하였다. 정상중력에서 V_s/V_F≤2일 때 차폐가스의 유동이 화염구조에 미치는 영향은 무시할 수 있었다. 정상중력에서 차폐가스가 없는 경우의 화염형태와 그 위치는 차폐가스가 있는 경우와 다르지만, 무중력에서는 중심선상에서 차폐가스의 영향력이 거의 없었다. The effects of shield gas on the structure of methane-air nonpremixed counterflow flames were numerically investigated. The near extinction flame of a low global strain rate 20_s^-t of 19% methane diluted by 81% nitrogen by volume and undiluted air was computed. The flame shape, centerline temperature and axial velocity profiles were compared for different velocity of the shield gas and with and without the shield gas. The effects of the velocity of the shield gas were negligible for V_s/V_f≤2 in normal gravity. Under normal gravity conditions, the flame shape and its position with the shield gas were different from those of the flame without the shield gas, whereas no discemible effects of the shield gas along the centerline were observed in zero gravity.

Analysis of the Effects of Shallow Gas on a Shield Tunnel during Leakage: A Case Study from the Sutong River-Crossing GIL Utility Tunnel Project in China

Xiaoqing Feng,Bin Ye,Xiaoyang Zhang,Yang Dai,Feng Xia 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.6

Soil layers including shallow gas threaten underground structures. Considering the special geological conditions of the gas-bearing layers under the Yangtze River for the Sutong River-crossing unity tunnel project, a solid-liquid-gas coupled 3-D numerical model was established to consider two different gas pocket conditions (a single gas pocket and multiple random gas pockets), and the effects of shallow gas on the tunnel segment and the adjacent soils in the long-term process of gas leakage were analyzed and discussed. A brief discussion of the displacement results and a comparison of the stress results determined by simulation and the designed data indicated that as the maximum displacement is on the order of millimeters for both gas pocket conditions and the simulated maximum bending moment is less than the design value for the bending moment, the structure of the tunnel segment has remained in a safe state during the leakage of the gas pocket, and the normal operation of the tunnel segment is basically not affected by the leakage of the gas pocket.

SM355강재의 플럭스 코어드 아크 용접에서 보호가스 및 용접자세에 따른 기계적 특성에 대한 실험적 연구

황세주,백재민,윤경수 한국강구조학회 2024 韓國鋼構造學會 論文集 Vol.36 No.1

This study experimentally evaluates the mechanical characteristics of welded parts of SM355 steel according to the welding position and shielding gases of FCAW (Flux Core Are Welding). The welding positions 1G, 2G, 3G are considered and CO2 gas and mixed gas(Ar 80% + CO2 20%) are considered as the shielding gas. Specimens are fabricated by welding SM355A which is a rolled steel plate for welded structures. Various tests including tensile, bending, hardness, impact, macro and non-destructure tests are conducted. It is confirmed that all test results satisfy the KS standard. Based on the test results, CO2 gas can be replaced with mixed gas as the shielding gas for FCAW of SM355 steel. 본 연구에서는 SM355강재의 FCAW(Flux Core Are Welding)시 용접자세 및 보호가스에 따른 용접부의 기계적 특성을 평가하였다. 용접자세로는 1G, 2G, 3G를 고려하였고 보호가스는 탄산가스(CO2 100% )와 혼합 가스(Ar 80% + CO2 20%)를 고려하였다. 인장시험, 굽힘시험, 경도시험, 충격시험, 매크로 시험, 비파괴 검사를 하였으며 모든 시험 결과는 KS 규격을 만족하는 것을 확인하였다. 실험 결과를 분석하였을 때 FCAW의 보호가스로 사용되고 있는 탄산가스를 혼합가스로 대체할 수 있을 것으로 판단 된다.

보호가스 종류에 따른 고출력 레이저 용접특성

안영남(Young-Nam Ahn),김철희(Cheolhee Kim) 대한용접·접합학회 2015 대한용접·접합학회지 Vol.33 No.4

Laser-gas metal arc hybrid welding has been considered as an alternative process of gas metal arc welding for offshore pipe laying. Fiber delivered high power lasers which enable deep penetration welding were recently developed but high power welding characteristics were not fully understood yet. In this study, the influence of shielding gas composition on welding phenomena in high power laser welding was investigated. Bead shapes, melt ejection and dropping were observed after autogenous laser welding with 100% Ar, Ar-20% CO₂, Ar-50% CO₂, and 100% CO₂ shielding gas. Process parameter window was widest with Ar-50% CO₂ shielding gas and the penetration was deepest with 100% CO₂ shielding gas. The melt dropping was not observed when Ar-50% CO₂ or 100% CO₂ shielding gas was supplied.

보호가스에 따른 Tailored Blank 레이저 용접성 평가에 관한 연구

이창희,박인수,유순영,정봉근 한국레이저가공학회 1998 한국레이저가공학회지 Vol.1 No.1

This study includes the effects of shielding gas types on CO2 Laser weldability of low carbon automotive galvanized steel. The types of shielding gas evaluated are He, CO₂, Ar, N₂, 50%Ar+50%N₂. The weld penetration, strength, formability(Erichsen test) of Laser weld are found to be strongly dependent upon the types of shielding gas used. Further, the maximum travel speed and flow rate to form a keyhole weld is also dependent upon types of shielding gas. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related with ionization/dissociation potential, which determine the period of plasma formation and disappearance. Further, thermal conductivity and reactivity of gas with molten pool also give strong effect on penetration and porosity formation which in turn affect on the formability and strength.

TIG용접에서 가스력을 이용한 비드형상제어를 위한 실드가스 노즐의 최적 형상에 관한 연구 (I) - 벤투리노즐의 설계 및 성능분석 -

함효식,서지석,최윤환,이연원,조상명,Ham, Hyo-Sik,Seo, Ji-Seok,Choi, Yoon-Hwan,Lee, Yeon-Won,Cho, Sang-Myung 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.3

Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was designed by using the Venturi meter and compared velocity, pressure, arc shape in the flat position with existing CP-nozzle. As a result, Venturi-type nozzle's maximum velocity and pressure was improved at the same flow rate. Also heat input was increased by the arc contraction in the flat position.

600MPa급 자동차용 고장렬강판의 $CO_2$ 레이저 용접부의 특성에 미치는 보호가스의 영향

한태교,이봉근,강정윤,Han Tae-Kyo,Lee Bong-Keun,Kang Chung-Yun 한국레이저가공학회 2004 한국레이저가공학회지 Vol.7 No.2

The effect of shield gas on the weldability, mechanical properties and formability of CO2 laser weld joint in 600MPa grade high strength steel was investigated. Bead on plate welds were made under various welding speed and shield gas. Tensile test was carried out under the load of perpendicular and parallel direction to the weld line, Formability of the joint was evaluated by Erichsen test. As the welding speed increases, the porosity fraction decreases. The porosity fraction in the joint used Ar-$50\%He$ mixed gas as a shield gas was lower than that of the joint used Ar gas. Hardness at the weld metal of full penetrated joint was nearly equal to that of water quenched raw metal. In a tensile test under a perpendicular load to the weld axis, strength and elongation of joint produced by optimum condition were nearly equal to those of base metal. However, the strength of joint in a tensile test under a parallel load to weld axis was higher than that of raw metal, but the elongation of joint was lower than that of raw metal. Elongation and formability were further increased by the method of using Ar+He mixed gas as a shield gas as compared with Ar gas. Formabilities of joints were recorded ranging from $58\%\;to\;70\%$ of that of base metal with different shield gases.

600㎫급 자동차용 고장력강판의 CO₂ 레이저 용접부의 특성에 미치는 보호가스의 영향

한태교(Tae-Kyo Han),이봉근(Bong-Keun Lee),강정윤(Chung-Yun Kang) 한국레이저가공학회 2004 한국레이저가공학회지 Vol.7 No.2

  The effect of shield gas on the weldability, mechanical properties and formability of CO₂ laser weld joint in 600㎫ grade high strength steel was investigated. Bead on plate welds were made under various welding speed and shield gas. Tensile test was carried out under the load of perpendicular and parallel direction to the weld line. Formability of the joint was evaluated by Erichsen test.<BR>  As the welding speed increases, the porosity fraction decreases. The porosity fraction in the joint used Ar-50%He mixed gas as a shield gas was lower than that of the joint used Ar gas. Hardness at the weld metal of full penetrated joint was nearly equal to that of water quenched raw metal. In a tensile test under a perpendicular load to the weld axis, strength and elongation of joint produced by optimum condition were nearly equal to those of base metal. However, the strength of joint in a tensile test under a parallel load to weld axis was higher than that of raw metal, but the elongation of joint was lower than that of raw metal. Elongation and formability were further increased by the method of using Ar+He mixed gas as a shield gas as compared with Ar gas. Formabilities of joints were recorded ranging from 58% to 70% of that of base metal with different shield gases.