• Journal of Advanced Marine Engineering and Technology
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• 제33권8호
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• pp.1162-1169
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• 2009

22APU 스테인리스강에 대해서 두가지의 용접법이 적용 되었으며, 그중 한 방법은 레이저 용접법이며 다른 하나는 TIG 용접법이다. 이 경우 상기한 두 용접을 적용할 경우 용접부의 부식특성의 차이점에 대해서 전기화학적인 방법 예를 들면 부식전위, 분극곡선 및 사이클릭볼타모그램 등의 측정에 의해서 고찰되어졌다. 레이저용접의 경우 모든 용접부(용접금속,열영향부, 모재부)의 경도가 TIG용접의 경우에 비해서 상대적으로 높은 값을 나타내었다. 더욱이 모든 용접부의 부식전류밀도 역시 TIG용접에 비해서 낮은 값이 관찰되었다. 특히 모재부의 부식전류밀도는 용접방법에 관계없이 가장 낮은 값을 나타내었다. 그리고 레이저용접의 경우 부식된 모든 용접부에서 입계부식이 관찰 되지 않았으나, TIG용접에서는 용접금속부와 열영향부에서 입계부식이 관찰되었는데 이것은 크롬카바이드의 형성에 의한 크롬결핍이 감수성온도영역에 있는 용접금속부와 열영향부에 나타났기 때문으로 사료된다. 따라서 이들 영역은 더욱 활성화된 양극으로 부식되기쉽다. 결과적으로 22APU 스테인리스강의 용접부의 내식성은 레이저용접에 의해서 확실히 개선될 수 있다는 사실을 알 수 있다.

• 한국생산제조학회지
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• 제25권1호
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• pp.48-53
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• 2016

An EMAT can be used to reliably detect defects as it serves as a non-contact transducer with the ability to transmit ultrasonic waves into specimens without couplant. Moreover, an EMAT can easily generate desired waves by altering the design of the coil and magnet. This study proposes an SH-EMAT to evaluate the integrity of the TIG welding part. A stainless steel was welded using the TIG welding method. The welding current was varied to create artificial defects. Both the PA-UT and the RT were applied to verify the defect size. The experimental results generated by using the EMAT were compared with those methods. The amplitude was observed to decrease with an increase in the defect size. These results confirmed that the presence of defects can be reliably detected by attenuation of signal amplitude. The results demonstrated that the proposed method is suitable for evaluating the integrity of TIG welding.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.632-638
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• 2002

Electron beam (EB) and Gas tungsten arc (TIG) welds were performed on 12.7 mm thick Ti-6Al-4V plate (ASTM Titanium Grade 5). Charpy-V toughness and hardness, as well as, microstructure of the welds and penetration from the macrostructure were studied. It appears that by EB welding rather smaller $\beta$-grains than with TIG welding can be obtained. Next to the fusion line the $\beta$-grain size in the HAZ was 50 ${\mu}{\textrm}{m}$l while in the weld metal it was 150 ${\mu}{\textrm}{m}$. Charpy-V toughness of the EB weld metal was equal or even better to that of base metal, which shows that the $\alpha$-martensite per se is not particularly brittle if only the grain size is fine enough. This is similar to behavior of low carbon martensite in steel. The grain size was studied with light optical and scanning electron (SEM) microscopes. Thus for products, for products which can be manufactured automatically with very narrow fit, the EB welding of Ti-6Al-4V appears to yield satisfactory toughness without any complex post weld heat treatment. ill this study as in earlier studies the TIG welds gave lower toughness than that of the base material due to the higher heat input and slower cooling as compared to EB welding.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.117-120
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• 2003

Joining or welding of dissimilar metallic materials is very difficult problem because material properties like heat conductivity, melting points, coefficient of thermal expansion, etc. are different each other and cracks are occurred easily due to formation of intermetallic compounds. Nevertheless, deep attention from great industrial demands and trials to joining dissimilar materials has been increased steadily. In this study, TIG welding of Cu to Al is tried and tensile test, SEM and EDX analysis are carried out.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.383-388
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• 1995

The ARC light has been measured using photo-detect system under different TIG welding condition. Light detect system consists of photo diode, ND Filter, OP Amp. A/D convertor and PC. The purpose of this experiment is to show the relationship between ARC light and process variables such as welding current, torch travel speed, etc. The results can be applied to estimate the condition of welding process and the quality of welding products. The signal of ARC light has periodic patterns in good TIG welding condition whereas in abnormal condition the signal has different pattern. Amount of Ar shielding gas and distance from electrode to specimen affect the signal pattern significantly.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.346-348
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• 2005

TIG welding can produce high quality of weld, but has the disadvantage of low productivity and high possibility of lack-of-fusion especially on heavy wall groove welding. In order to overcome such demerits of TIG welding, the hot-wire method which provides pre-heated wire and the use of He-Ar mixture gas as shielding gas were adopted. Through this study, both methods were turned out to be beneficial to the prevention of lack-of-fusion and the increase of productivity and welding speed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.792-795
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• 1996

In TIG welding of pipe, back bead size monitoring is important for weld quality assurance. Many researches have been performed on estimation of the back bead size by heat conduction analysis. However numerical conduction model based on many uncertain thermal parameters causes remarkable errors and thermomechanical phenomena in molten pool can not be considered. In this paper, filler wire feeding force in addition to weld current, wire feedrate, torch travel speed and orbital position angle is monitored to estimate back bead size in orbital TIG welding. Monitored welding process variables are fed into an artificial neural network estimator which has been trained with the monitored process variables (input patterns) and actual back bead size (output patterns). Experimental verification of the proposed estimation method was performed. The predicted results are in a good agreement with the actual back bead shape. The results are quite promising in that estimation of invisible back bead shape can be achieved by analyzing the welding parameters without any conventional NDT of welds.

• Journal of Welding and Joining
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• 제26권6호
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• pp.42-47
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• 2008

TIG welding enables to produce high quality weldment. However it has some problems such as shallow penetration and large distortion due to low penetration aspect ratio after welding. In order to overcome those problems, there are many ongoing studies on A-TIG welding, which use active flux. In this study, the effect of arc length and shield gas on penetration aspect ratio with melt-run welding on STS 304 6t, on which active flux was spreaded, was investigated. Arc length was changed from 1mm to 3mm, and aspect ratio became higher as arc length was decreased in this range. 100% Ar gas, Ar-$H_2$ mixed gas, Ar-He mixed gas, and 100% He gas were used as shield gas in this study. When Ar-$H_2$ mixed gas, Ar-He mixed gas, and 100% He gas were applied, penetration and melting efficiency were both increased as compared with 100% Ar gas. Aspect ratio was the highest with Ar-2.5% $H_2$ mixed gas.

• 한국정밀공학회지
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• 제29권10호
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• pp.1078-1088
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• 2012

In this paper, we present research experimental results about the different thickness T-joint welding of the high power continuous wave(CW) Nd:YAG laser for the secondary battery of a vehicle. Although the conventional method used for the secondary battery is a argon TIG welding, we utilize a laser welding to improve Tungsten Inert Gas(TIG) welding's weakness. The laser, which has a couple of advantage such as aspect ratio, low Heat Affected Zone(HAZ), good welding quality and fast productivity utilized in this work is a CW Nd:YAG laser. In order to observe laser welding sections, we used a optical microscope. Through the analysis of the metallographic, hardness, aspect ratio, and heat input, we obtained the desired data in condition of 1800 W laser beam power and 1.8 m/min and 2.0 m/min laser beam travel speeds. In order to compare electric resistances of the argon TIG welding and laser welding, we made an actual battery and the electric resistance of the laser welding is reduced by 40~45% comparing with the argon TIG welding.

• Journal of Welding and Joining
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• 제30권2호
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• pp.11-15
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• 2012