• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.553-558
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• 1999

As a process of development of composite beam-column connection system, structural tests have been conducted to verify moment resisting performance of the system. The tests have been proceeded by two steps, the first being welding performance test of the steel connection rod and stiffners, and the second overall moment resisting capacity of the fuly assembled system. Ten welding test specimens and four prototype specimens have been used in the test. Good structural performance of welding test specimens has been observed without any single welding failure, and sufficient moment resisting capacity has been proved from the overall performance test, with the moment magnitude in excess of the calculated plastic moment.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.72-74
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• 2006

The application of the variable polarity plasma arc welding process to A12219 is described. The thickness of aluminum alloy is 11.45mm and 5.08mm. 1-pass keyhole welding is applied to butt welding and 2-pass welding is also applied to thick material. During welding, all welding parameters are controlled by automated system and acquired by 10kHz rate. This paper covers the welding parameters, result of non-destructive test and tensile test.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.8-13
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• 2002

In order to obtain the basic informations for the development of high strength and high weldability aluminum alloy sheets, the experimental study was carried out to evaluate resistance spot welding characteristics and welding parameters (welding current, welding time, electrode force) far the aluminum alloy sheets. The mechanical properties of spot weld of aluminum alloy were evaluated by tensile shear test and by peel test at room temperature and also the welding possible zone was established through variation of current electrode force and welding time.

• Journal of Welding and Joining
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• v.20 no.1
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• pp.55-61
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• 2002

The automobile is made up of about twenty thousand parts. Some parts are formed by pressing and combined by spot welding. Among them, steel palate of fuel tank is formed in the metal mold and bending parts are jointed by spot and seam welding. To find weldability conditions of spot welding, clearance between two welding steel plates was made and after spot welding, weldability is evaluated by means of tensile shear load, nugget size and shape. Specimen used in this study was a mild steel of 1.2mm thickness and electrode was Cu-Cr alloy of 6mm diameter. When spot welding started, the clearance of two steel plates was changed 0mm, 3mm and 5mm step by step. The fractured surface of specimen after this test was observed by Optical Microscope to measure microstructure and nugget shape. When clearance of two specimen was 3mm and 5mm, strength and nugget size was decreased and nugget shape was not clear.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.290-292
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• 2004

In this paper, static and fatigue load tests for the specimens, components and carbody were carried out to investigate the strength of welded joints in aluminum rolling stock. Tensile load test results showed that the static strength of welded joint for heat-treated alloys is reduced significantly and fatigue strengths are scattered by the welding imperfections. Component and whole carbody fatigue test results showed agreements with the design fatigue strength standards for specimens of same joint detail. Test results revealed that full penetration welding and strict management of welding procedure are crucial for securing strength of welded joint in aluminum carbody.

• International Journal of Korean Welding Society
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• v.1 no.1
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• pp.13-16
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• 2001

High speed seam weldability of tin coated steels was investigated. Welding was performed by the laboratory wire seam welder that was equipped with process monitoring system Test results showed that increase in applied current and pressure reduced the total resistance across the welding electrodes. Lower and upper limits of welding current increased as the sheet thickness increased, while the acceptable welding condition range decreased. However, extremely low electrode pressure produced unstable welding condition range. The results also demonstrated that slower welding speeds widened the optimum welding heat input range.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.28-36
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• 1999

Wet underwater arc welding process is investigated by using experimentally developed flux coated underwater arc welding electrode and SS400 steel plate of 12mm thickness as base metal. Three kinds of different flux covered wet arc welding electrode of 4mm diameter(BK-01, BK-02, BK-03) are individually developed, and one of the improved underwater welding electrode (BK-03) may be put to practical use for underwater wet arc welding process. The results obtained from this experimental study are as follows : 1. Arc stability of developed underwater wet welding electrode is better than that of the domestic covered arc welding electrode. 2. Workability of welding electrode, remove ability of slag and bead appearances using improved underwater wet welding electrode are remarkably better than that of others. 3. Heat affected zone of test specimen welded in the underwater gets to become a lot smaller than that of test specimen welded in the air, and the maximum hardness of heat affect zone of developed underwater wet welding electrode is lower to that of domestic arc welding electrode.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.582-589
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• 2000

In recent automotive industry, vehicle weight can be reduced by one-step forming of tailored blanks welded with two or more sheets of metal blanks. Mash seam welding shows an overlap joint, a much wider welding area, and heat affected zone(HAZ) than a laser welding. This paper deals with the forming characteristics of mash seam welded tailored blanks. Mash seam welded blanks of same or different thickness combinations were prepared, and tensile, hardness, erichsen, and dome stretching tests were done.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.49-56
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• 2005

In spite of the merits of laser welding being able to obtain the high welding quality such as smaller width of melting and heat affected zone, smaller welding deformation and fine grains of weldment compared to arc welding, laser welding is mainly used in joining of thin steel parts of electronics industry. Laser welding is getting widely used in joining thick plate and special kinds of steel due to its high power. While the arc welding is still applied for 2.25Cr-1Mo steel which is the essential material of atomic power generation equipment, the laser welding is not yet applied despite its high quality. So it has a trial to a special case demanding high welding quality such as atomic power plant. Accordingly, in this research, the mechanical properties of weldments by arc and laser welding were investigated using FEM to confirm the applicability of laser welding to 2.25Cr-1Mo steel. The Charphy test was carried out to understand the effect on the fracture toughness of weldments. The results of examination and test of the mechanical properties showed the validity of this research.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.81-88
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• 2014

As the industrial technology has been developed, a dissimilar welding has been received huge attention in various engineering fields. To understand the mechanical properties and possibility of applications of dissimilar metals joining, the laser welding of Cu and Ni dissimilar metals was studied in this paper. Cu and Ni have differences in materials properties, and Cu and Ni make no intermetallic compounds according to typical binary phase of Cu and Ni system. In this study, lap welds of Cu and Ni dissimilar metals using single-mode fiber laser with high welding speed were tried, and mechanical properties of the welds zone were evaluated using a Vickers hardness test and a tensile shear test. To recognize the relation between hardness and tensile shear load, weld fusion zone of interface weld area were observed. And it was confirmed that the ultra-high welding speed could make good weld beads and higher hardness parts had higher tensile shear load under the all conditions.