• Proceedings of the KWS Conference
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• 2010.05a
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• pp.42-42
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• 2010

알루미늄 합금은 질량 대비 강도가 우수하고 내식성 및 저온 특성이 양호하여 구조재로서 널리 사용되고 있다. 또한 그 사용 추세가 점점 증가 하고 있으며 알루미늄 합금의 용접을 위해 현재까지 다양한 용접 공정이 적용되었다. 일반적으로 GMAW, GTAW 등의 아크 용접과 박판의 경우 저항 점용접, 그 외의 $CO_2$ laser, Nd:YAG laser와 같은 고밀도 에너지 용접 공정에 의한 연구 결과들이 많이 발표 되었다. 하지만 알루미늄 합금의 특성 상 용접부에 기공과 균열과 같은 결함들이 각 공정에서 많이 발생하며 이러한 결함을 감소시키기 위한 용접기술에 관해 많은 연구가 진행되고 있다. 본 연구에서는 GMAW, Plasma-GMAW 공정을 적용하여 알루미늄 합금의 용접특성을 비교하였다. 알루미늄 합금 Al 5052, Al 6061 4mm 두께 모재에 대해 BOP(Bead On Plate) 용접실험을 실시하였으며 생산성 측면에서 각 공정에 따라 완전 용입 시 최대 용접 속도를 측정하여 비교하였다. 용접 품질 측면에서는 비드 표면 및 단면을 검사하고 인장시험을 수행하였으며, 용접 기공과 균열을 X-ray 촬영을 통해 비교하였다. 또한 고속카메라 촬영을 통해 용접 중 플라즈마로 인한 산화막 제거 효과를 확인하고 각 공정별 용접 시작부의 아크 안정성을 평가하였다. 인장시험 결과 모든 모드에서 모재에서 파단됨을 확인 하였고, Plasma-GMAW 공정의 경우 플라즈마의 예열효과로 인하여 GMAW 보다 완전용입 기준 용접속도가 빨랐으며, 청정작용도 우수한 것으로 확인되었다.

• Journal of Welding and Joining
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• v.14 no.5
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• pp.113-121
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• 1996

The arc sensor has been most widely used for weld seam tracking through welding current or voltage variation. In this work, the relation between the arc light intensity and welding condition is investigated using heat balance in the Plasma for its possible application to seam tracking in the GMAW process. The arc light intensity is derived to be the function of the arc length and welding current Experiments are carried out to verify the proposed heat balance model. Performances of least square and integration methods to process the signals for seam tracking are compared experimentally. Predicted arc light intensity shows reasonably good agreement with experimental results. The weld seam is successfully tracked through the arc light intensity. The least square and integration methods demonstrate almost same performance of seam tracking with $CO_2$gas shielding.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.21-30
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• 2017

Of the marine engine components, the piston crown and exhaust valve are repaired most frequently. These works are conducted through conventional welding processes such as GTAW or SAW, domestically in marine engine repair factories. New high-efficiency welding or overlay processes such as tandem SAW, tandem MAG, hybrid TIG-MIG welding, pulsed-GMAW, CMT welding, and super TIG welding have been developed recently. Moreover, the plasma transfered arc (PTA) process is an efficient spray method for overlaying on the exhaust valve. In this review paper, the new high-efficiency repair welding methods are introduced for marine engine components. The problems due to repair welding for marine engine components are also presented.

• Journal of Welding and Joining
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• v.33 no.4
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• pp.50-56
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• 2015

In general, discontinuity of metallurgical and structural points of weld zone could decline the fatigue strength. For the lightweight trend, the AHSS application in automotive chassis is in-progress. However, there are few research reports on AHSS welds fatigue strength in especially automotive chassis parts. Therefore, in this study, we evaluated the effects of the factors affecting the AHSS welding fatigue strength. As the result, the stress concentration of weld bead is the most important factor for welding fatigue strength. For the enhancement of welding fatigue strength, we focused on reducing the stress concentration of the welding beads. So, we applied and proved the plasma welding process and GTAW (Gas Tungsten Arc Welding) dressing method. It was verified by uniaxial fatigue specimen, fatigue performance increased from 40 to 60% by applying TIG dressing method compared to the conventional GMAW (Gas Metal Arc Welding). These results could be recommended the enhancement of fatigue performance of AHSS.