GTAW에 의한 Al 합금 용접부의 조직 및 결합에 대한 연구

하려선,정병호,박화순 대한용접접합학회 2003 대한용접·접합학회지 Vol.21 No.5

Recently Al alloys are being used gradually for structural materials of transports. In welding of Al alloys used for transports, good weldabilities as well as adequate mechanical properties of the welds should be ensured as structural materials. In this study, the welds formation, macro and microstructural characteristics, generation of defects and hardness distribution in welds of Al alloys of 5083, 6N01 and 7N01 by DCSP- and AC-GTA welding process, were investigated. The deeper penetration was obtained in all welds of the alloys by DCSP-GTAW with He gas, compared with those by using AC-GTAW. The 6N01 alloy showed high susceptibilities to solidification cracking in weld metal and liquation cracking in HAZ of the welding beads of both DCSP- and AC-GTAW process. The cracking ratio of 6N01 alloy was increased with increasing of welding current. The porosity ratios in weld metal of all alloys used were extremely low including all welding conditions of DCSP-GTAW. However, in AC-GTAW process, the porosity ratios of the welds using Ar gas showed much higher values than those using He gas.

AZ60 마그네슘합금을 이용한 용접 공정별 접합부 특성 평가

김부민,김인규,이한섭,박상흡 한국기계기술학회 2017 한국기계기술학회지 Vol.19 No.2

In this study, the mechanical characteristics with micro structure were analyzed on the butt joint of AZ60 magnesium material extruded by GMAW and GTAW processes. As the result of tensile test, the fracture in the welding joint area happened at both processes and seemed to be brittle fracture. The yield strength of GMAW was 84.29% and GTAW was 60.43% as compared with base metal. The yield strength of GMAW was higher 23.86% than that of GTAW. The result of decreased micro hardness was indicated at both processes. The value of minimum micro hardness in FZ at GMAW was Hv 46.7 and GTAW was Hv 43.6 as compared with base metal. The value of minimum micro hardness at GMAW process was higher 5.64 % than that at GTAW process. The size of grain boundary at GMAW process in HAZ is smaller than that at GTAW process. GMAW process is more superior than GTAW process from the productivity and quality in case of automatic welding for magnesium alloy such as the automobile seat frame.

알루미늄 熔接構造物의 變形橋正을 위한 Autogeneous GTAW의 適用 可能性 硏究

하용훈,강춘식,유순영 대한용접접합학회 1992 대한용접·접합학회지 Vol.10 No.1

Characteristics of two correcting methods, a new Autogeneous GTAW heating (TIG) method and the conventional GMAW bead-on plate welding(MIG) method, for distorted aluminum fabrication structures were studied. As a result of microscopic study of Autogeneous GTAW heating and GMAW bead-on plate welding areas, porosities in weld metal and surface cracks in local heating zone were found. Through the mechanical tests, it was verified that porosities decrease tensile strength and surface of distortion, angular displacement and transeverse shrinkage were measures and compared. In order to investigate changes of material properties in heating area and cause of defects such thermal stresses were calculated by ADINA. Through the computations of transient thermal stresses and microscopic observation of fracture surface, thermal stress was found to be the cause of crack during Autogeneous GTAW heating.

K11B59A 소재에 대한 GTAW용접을 이용한 스텔라이트 육성용접 방법연구

임경달(Kyung-Dal Lim) 산업기술교육훈련학회 2010 산업기술연구논문지 (JITR) Vol.15 No.3

When people want to use some material in industry, they can get if they try to use its advantage as much as possible and reduce its disadvantage. We can replace to new products or maintain the original things, in case original metal is malfunctioned and worn out by outdoor shock, physical, or chemical change. Supposing they intend to replace to high priced product, it can be difficult for business budget. In the second choice, they can fix the original products. But if they use stellite welding to fix K11B59A material, it also costs a lot, companies have big financial burden. In most cases, people repair used things at this time, most problem is the loss of material parts by outer shock, abrasion, or erosion. At this situation, people use after welding for missing parts and reprocessing. Or they can prolong its durability by plating other superior metal on the surface of the used metal. These methods are called abrasion resistance welding and filler welding. abrasion resistance welding is the way that attach more than 1mm thick metal has good resistance about erosion, high temperature, and abrasion to metal. The welding rod used on the surface is more expensive than common welding rods and Stellite is used commonly. Stellite is mixed Cr, W, and Mo, Co, is discovered by Swedish chemist brandt Georg in 1735, after then in 1907 Stellite with more than 50% Co. is discovered. Also strong magnetism alloyed steel with 20∼60% Co. is discovered in Japan in 1917. Stellite can conserve magnetism even though it is in high temperature like 1130℃. The purpose of this study is just to obtain superior product that has high quality without defects by using Stellite and GTAW welding.

ArcTig 용접 특성분석을 통한 TIG용접 생산성 향상에 관한 연구

전성현,주우현,신재민,김태완,김유찬 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.11

ArcTig는 GTAW(Gas Tungsten Arc Welding)의 일종으로 텅스텐 전극을 냉각시켜 수축된 형상의 아크를 만들 수 있는 프로세스이다. 냉각된 전극으로 인해 일반적인 GTAW보다 수축된 아크가 전극의 끝 부분에서 형성된다. 수축된 아크는 높은 에너지밀도를 갖기 때문에 GTAW임에도 불구하고 고에너지 용접에서나 가능한 Keyhole 용접이 가능하다. 본 연구에서는 이러한 ArcTig의 사용에 있어서 프로세스의 Operating points 범위를 도출하였다. 실험은 용접속도와 아크길이를 3수준으로 설정하고 전류를 변경시키며 실험을 진행하였다. 비주얼 및 횡단면 분석을 통해 각 조건에서 용입불량(IP)이나 용락이 발생한 경우는 제외하였으며 각각의 조건에서 operating points를 도출하였다. 또한 실험 중 발생한 결함에 대해서 고찰하였다.

9% Ni강의 Alloy 625 용접재료 적용에서 GTAW와 FCAW의 고온균열 발생 특성 비교

나기범,이창익,박정현,조상명 대한용접접합학회 2019 대한용접·접합학회지 Vol.37 No.4

Recently, demand for LNG storage and fuel tanks has been increasing due to the International Maritime Organization(IMO) regulations on sulfur oxides and greenhouse gas emission. In the production of LNG tanks, 9% Ni steel is used and Alloy 625 or Hastelloy wire are used as the filler materials. In the FCAW welding process using Alloy 625 consumables, when using high current to increase productivity, hot cracking frequently occurs as well as welding defects such as lack of fusion due to arc instability. In this study, the hot cracking characteristics of FCAW and GTAW using Alloy 625 consumables in 9% Ni steel welding were compared through the FISCO hot cracking test.

STS316L 강관의 수평자세 용접을 위한 GTAW 용접조건의 최적화

이형근(Hyoung-Keun Lee),방경식(Kyoung-Sik Bang) 대한용접·접합학회 2015 대한용접·접합학회지 Vol.33 No.5

In this study, it was tried to analyze the effects of welding parameters on the weld penetration and aspect ratio when a STS316L pipe was welded in a horizontal position by GTAW. Experiments were systematically designed using a L18 orthogonal array, and the effects of welding parameters were statistically analyzed by ANOVA(Analysis of Variance). The shielding gas type has the largest effect on both the penetration and aspect ratio. The welding current type and shielding gas flow rate have a little effect on the penetration, whereas the electrode tip angle has a little effect on the aspect ratio. When welded at a selected welding condition, which is composed of He shielding gas, pulse current of 300/45 A, electrode tip angle of 90o, and shielding gas flow rate of 30 l/min, the estimated interval at least 95 % confidence was 1.99 ± 0.18 ㎜ for the penetration and 0.31 ± 0.04 for the aspect ratio. From the confirmation experiments, the average penetration and aspect ratio were well agreed with the estimation as 1.96 ㎜ and 0.30, respectively. Additionally, the effects of the welding speed and welding current on the penetration and aspect ratio were experimented and analyzed by linear regression. The penetration was linearly increased with the decrease of the welding speed and with the increase of the welding current, but the aspect ratio showed a tendency to a little decrease with the increase of both the welding speed and current.

GTAW를 적용한 맞대기 초층 용접에서 이면 비드 형성 조건에 관한 연구

Daekyu Park,송창섭,박영환 대한용접접합학회 2023 대한용접·접합학회지 Vol.41 No.5

GTA welding is a representative welding technique applied to root pass welding of piping. The pipe root pass welding significantly influences the determination of welding parameters owing to the root gap and step change occurring during installation. GTA welding has the advantage of being able to control current (A) and wire feeding speed (WFS) as independent variables; however, determining these variables is difficult. In this study, the change in the back bead height (Bbh) was observed by changing the root gap and WFS while the welding speed and welding current (A) were fixed. By fixing the welding speed and changing the welding current (A), root gap, and WFS, the gap bridging possible condition was expressed as a region. When the root gap changed from 0~1 mm and from 1~2 mm, the back bead height was greater than or equal to 0 mm. Possible welding current and WFS and the setting range of the welding heat input ratio (HIR) were presented.

GTAW에서 텅스텐 전극봉 각도에 따라 모재의 용입에 미치는 영향에 관한 연구

민용기(Yong Gi Min) 산업기술교육훈련학회 2018 산업기술연구논문지 (JITR) Vol.23 No.1

In the welding field, there was always doubt that how the angle of the tungsten electrode bar impacts the penetration of the base metal. There are opposing views relating to penetration on some literature, so the author wants to confirm the facts through experiments. In this study, the author collected and analyzed the data about the change of penetration according to various angles and currents of electrode bar by automatic liner welding. The relation between electrode angle and penetration is rising as a controversial subject among the welding experts. This study paper will help to establish that relationship and it will be a reference for in the welding field.

GTAW에 의한 스테인리스강 용접부위의 부식특성에 관한 전기화학적 평가

문경만(Kyung-Man Moon),이규환(Kyu-Hwan Lee),김진경(Jin-Gyeong Kim) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회지 Vol.34 No.4

STS304와 22APU 스테인리스강에 가스 텅스텐 아크용접을 하였다. 이 경우 두 강의 용접부의 부식특성을 전기화학적 방법으로 검토하였다. STS304 용접금속의 경도(Hv-250)는 22APU 강 (Hv-217) 보다 상대적으로 높은 값을 보였다. 22APU의 용접금속과 STS 304의 열영향부의 부식전류밀도는 다른 용접부위와 비교하여 각각 높은 값이 관찰 되었으며, 이것은 예민화 온도 영역에 있는 STS304의 열영향부와 22APU의 용접금속에 형성된 크롬탄화물로 크롬결핍이 더욱 활성태의 양극으로 쉽게 부식된 것에 기인하는 것으로 사료된다. 그리고 이들 두 강의 용접금속과 열영향부는 크롬결핍상태에 있는 입자 사이 경계의 선택부식으로 입계부식을 나타내었다. 결과적으로 다른 용접방법의 적용이나 적절한 용접봉 사용은 두 강의 용접부에 대한 내식성을 개선하기 위해서 필요한 것으로 사료된다. GTAW was carried out to the austenitic 304(STS 304) and 22 APU stainless steels. In this case, difference of the corrosion characteristics of welded zone with STS 304 and 22APU mentioned above was investigated with electrochemical methods. Vickers hardness of weld metal in case of STS 304 (Hv-250) showed a relatively higher value than this of 22 APU(Hv-217). The corrosion current densities of weld metal of 22APU and heat affected zone of STS 304 were observed at the highest value compared to those of other welding zone respectively. This is probably because chromium depletion field due to chromium carbide formed to weld metal of 22APU and to heat affected zone of STS 304 can preferentially easily be corroded with more active anode than other fields. Consequently it is thought that application of the other welding methods like as laser welding or using of the optimum filler metals is necessary to improve the corrosion resistance of welding parts of these steels.