• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.15-15
• /
• 2009

최근 컨테이너선은 점차 대형화되고 있으며, 이에 따라 선체의 외판 상부의 철판 두께도 최대 80mm 까지 설계되고 있다. 블록 외판의 수직 맞대기 용접의 경우 고능률 용접기법인 Electro Gas Weldig(이하 EGW)이 적용되고 있으나, 극 후판의 경우, 기존의 한 개의 전극만으로는 적용 가능한 두께 범위의 한계가 있어 수직 맞대기 용접의 용접생산을 향상시키기 위해 2개의 전극을 사용하는 탄뎀 EGW 기법에 의한 시공법이 고려되었다. 탄뎀 EGW 기법의 시공법에 관한 보고서는 국내외에서 많이 발표되어져 왔다. 하지만 실선 적용에 있어 두께 80mm, 길이 2M 이상의 철판을 안정적으로 용접하기 위한 장애요소는 용접 중 적절한 슬래그의 배출 조절이다. 두개의 용접 와이어를 동시에 공급할 때 발생하는 슬래그를 균형있게 배출하지 못하는 경우 용융, 금속 상부에 적층되는 슬래그의 양이 증가하게 되고, 아크는 불안해져서 전극팁에의 슬래그 부착, 전극 팁의 발열 등에 의한 요인들이 송급을 불안하게 하여 연속 용접이 어려워진다. 본 연구에서는 탄뎀 EGW 기법을 실제로 현업에 적용하기 위해서는 안정적인 슬래그 배출에 착안하여 동당금의 형상에 따라 슬래그의 배출 성능을 확인하고 형상별 전류, 전압 파형을 측정하고, 파형 결과에 따라 아크 안정성을 평가함으로서 탄뎀 EGW 용접기법에 적정한 동당금을 설계한 결과를 소개하고자 하였다.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.2
• /
• pp.137-146
• /
• 2011

In the fabrication of steel bridges, blast cleaning prior to painting is carried out on the steel members to clean the forged surface and to increase the adhesive property of the applied painting systems. The effect of blast cleaning on the fatigue strength improvement of the weld joints, however, is not clear. In this study, Almen strips and steel specimens were blast-treated, conforming to ten types of blast-cleaning conditions deducted from the blast-cleaning conditions of seven steel structure fabrication companies. The arc height, roughness, hardness, and compressive residual stress were measured before and after the implementation of the ten blast-cleaning methods, and the relationship between the blast conditions and the measured values was studied. The geometry of the weld toe and the compressive residual stress near the weld toe were also measured before and after the blast cleaning of the butt-welded joints, and fatigue tests were carried out on the butt weld joints. The test results showed that blast cleaning significantly increases the fatigue strength and limit.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.4
• /
• pp.871-877
• /
• 2008

It is important to investigate the relationship between weld process parameters and weld bead geometry for adaptive arc robot welding. Howeve, it is difficult to predict an exact back-bead owing to gap in process of butt welding. In this paper, the quantitative prediction system to specify the relationship external weld conditions and weld bead geometry was developed to get suitable back-bead in butt welding which is widely applied on industrial field. Multiple regression analysis for the prediction of process parameters was used as the research method. And, the results of the prediction method were compared and analyzed.

• Proceedings of the KWS Conference
• /
• 2006.10a
• /
• pp.20-22
• /
• 2006

• Proceedings of the KWS Conference
• /
• 2005.11a
• /
• pp.141-143
• /
• 2005

• Proceedings of the KWS Conference
• /
• 1995.04a
• /
• pp.58-61
• /
• 1995

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.2 s.245
• /
• pp.187-193
• /
• 2006

The butt and the lap welding by friction stir welding performs with $2mm^t$ 1050 aluminum alloy sheet. This paper shows behaviors of property such as vickers hardness, yielding and ultimate stresses, and macro structures for weld zone cross section of the butt and the lap jointed specimens. It is also carried out making comparison with maximum loads, stress-strain diagrams, and deformation after the guided bending test and fracture behaviors between the butt and the lap jointed specimens. It is found that the weldability of the butt jointed specimen is better than that of the lap jointed specimen.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.1
• /
• pp.47-54
• /
• 2013

This study investigates the crack growth behavior due to primary water stress corrosion cracking (PWSCC) in the dissimilar metal butt weld of a reactor piping using Alloy 82/182. First, detailed finite element stress analyses were performed to predict the stress distribution of the dissimilar metal butt weld in which the hydrostatic and the normal operating loads as well as the weld residual stresses were considered to evaluate the stress redistribution due to mechanical loadings. Based on the stress distributions along the wall thickness of the dissimilar metal butt weld, the crack growth behavior of the postulated axial and circumferential cracks were predicted, from which the crack growth diagram due to PWSCC was proposed. The present results can be applied to predict the crack growth rate in the dissimilar metal butt weld of reactor piping due to PWSCC.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.21 no.2
• /
• pp.194-199
• /
• 2015

In this study, experiments of welding deformation considering dog-pieces setting were performed to assess the effect of dog-pieces on welding deformations quantitatively and an analysis method of welding deformations considering dog-pieces was proposed. Experimental results show the relationship between welding deformations and dog-pieces setting quantitatively. The maximum reduction of welding deformation was measured as 74%. The proposed numerical analysis method to predict welding deformations is one of thermal elasto-plastic analyses using a circular heat flux and finite elements model and has been verified through experiments of welding deformation. The proposed analysis method is expected to be used in a variety of fields as an analysis tool to assess or establish guidelines for a proper use of dog-pieces.

• Proceedings of the KWS Conference
• /
• 1998.05a
• /
• pp.227-229
• /
• 1998