• Proceedings of the KWS Conference
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• 2008.05a
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• pp.51-51
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• 2008

• Proceedings of the KWS Conference
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• 2008.05a
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• pp.48-48
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• 2008

• Journal of Welding and Joining
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• v.31 no.6
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• pp.58-64
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• 2013

Several joining methods involving resistance welding, laser welding, ultrasonic welding and mechanical joining are currently applied in manufacturing lithium-ion batteries. Cu and Al alloys are used for tab and bus bar materials, and laser welding characteristics for these alloys were investigated with similar and dissimilar material combinations in this study. The base materials used were Al 1050 and oxygen-free Cu 1020P alloys, and a disk laser was used with a continuous wave mode. In bead-on-plate welding of both alloys, the joint strength was higher than the strength of O tempered base material. In overlap welding, the effect of welding parameters on the tensile shear strength and bead shape was evaluated. Tensile shear strength of overlap welded joint was affected by interfacial bead width and weld defect formation. The tensile-shear specimen was fractured at the heat affected zone by selecting proper laser welding parameters.

• Journal of Welding and Joining
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• v.28 no.6
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• pp.45-50
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• 2010

Most of joining processes for machine and steel structure are performed by butt and fillet welding. The mechanical properties and fatigue strength of their welding zone can be effected largely by the differential of generated heat and changes of grain size according to thickness of material and number of passes in welding process. In this study, it was investigated about characteristics of fatigue failure according to thickness of material and number of passes in cruciform fillet weld zone as the basic study for safe and economic design of welding structures. Fracture modes in cruciform fillet weld zone are classified into toe failure and root failure according to non-penetrated depth. It can be accomplished economic design of welding structures considering fatigue strength when the penetrated depth in fillet weld zone is controled properly.

• Journal of Korea Foundry Society
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• v.15 no.6
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• pp.546-557
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• 1995

This study was undertaken to obtain an improved understanding of the effects of alloying elements on the residual amounts of Mg in the melt and on the resultant microstructure of compacted vermicular graphite cast irons, and the influence of alloying elements and cooling rates during solidification on the formation of phosphide eutectics, and on the mechanical properties of compacted vermicular graphite cast irons containing copper, tin, molybdenum for producing pearlitic matrix, and also containing phosphorus and boron for increasing wear resistance were evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.1
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• pp.77-82
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• 2017

A computer simulation method is introduced to understand the joining phenomena of PC and CFRP by estimating the temperature of the weld zone. Following the prior or preliminary research, the power range was set between 3 watts and 7 watts, and the scanning speed was set at 500 mm/min and 1,000 mm/min, respectively. Based on the computer simulation, the temperature near the joining boundary was not sufficient at the scanning speed of 1,000 mm/min, regardless of the selected powers. However, the temperature increases above the melting temperature of the selected polymers at the scanning speed of 500 mm/min. The simulation results were compared with actual weld samples to validate its actual use.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.32-40
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• 1997

Solid state diffusion bonding is the joining process performed by creep and diffusion, which is accelerated by heating below melting temperature and proper pressing, in vacuum or shielding gas atmosphere. By this process we can obtain sufficient joint which can't be expected from the fusion welding. For Ti-6Al-4V alloy, the optimum solid state diffusion bonding condition and mechanical properties of the joint were found, and micro void morphology at bond interface was observed by SEM. The results of tensile test showed sufficient joint, whose mechanical properties are similar to that of base metal. 850$^{\circ}$C, 3MPa is considered as the optimum bonding condition. Void morphology at interface is long and flat at the initial stage. As the percentage of bonded area increases, however, small and round voids are found. Variation of void shape can be explained as follows. As for the void shrinkage mechanism, at the initial stage, power law creep is the dominant, but diffusion mechanism is dominant when the percentage of bonded area is increased.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.62-66
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• 2013

Overlay welding is carried out to improve the corrosion resistance, wear resistance and heat resistance on the surface of the chemical plant and steelmaking plant structures. In overlay welding, control of the bead size and the temperature distribution of weldment are particularly important because that is directly connected to the improvement of quality and productivity. The aim of this study is to model the welding heat source that is very useful to analyze the bead size and temperature distribution of weldment. To find the welding heat source model, numerical analyses are performed by using FE software MSC-marc.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.9-16
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• 2009

In this paper, the coaxial monitoring system to capture image of weld pool was developed in laser-arc hybrid welding. In order to obtain the reliable image, green laser was used as a illumination system and measuring components such as band pass filter, ND (Neutral Density) filter and shutter speed was designed and optimized. Using this monitoring system, weld pool images were captured according to laser power, welding speed, welding current and interspace between laser and arc through the experiment. ANOVA (Analysis of Variation) was carried out to identify the influence of process variables on bead widths extracted from captured images of monitoring system. Welding speed and current were major factor to affect weld pool.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.110-110
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• 2009

본 연구에서는 전산유체역학적 방법을 이용하여 레이저-GMA 하이브리드 용접에서 용융풀 거동에 대한 3차원 과도해석을 수행하였다. 철강재의 주요 합금원소 중 하나인 크롬의 용융풀에서의 거동을 구현하기 위해 크롬에 대해 추가적인 보전 방정식을 도입하였다. 이를 이용하여 합금원소 분포에 대한 용접 변수별 영향을 해석적으로 분석하였으며 이를 EPMA(Electron Probe Micro Analyzer)를 통해 분석한 시험결과와도 비교하였다. 결과적으로 용접변수 중 선행 조건이 합금원소 분포에 구별할만한 영향을 미침을 알 수 있었고 이는 용융풀의 거동을 지배하는 주요 유동 패턴의 상이함에 기인한 것으로 보여진다.