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  • Title/Summary/Keyword: Hybrid joining

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Characteristics and oxidation behavior of the hybrid-HVOF sprayed Cr3C2-7wt%(NiCr) coatings depending on H2/O2 ratio (H2/O2 비에 따른 Hybrid HVOF 용사된 Cr3C2-7wt%(NiCr) 용사층의 특성 및 산화거동)

  • 김병희;서동수
    • Journal of Welding and Joining
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    • v.15 no.4
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    • pp.126-135
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    • 1997
  • H2/O2 비에 따른 Hybrid HVOF 용사된 Cr3C2-7wt%(NiCr) 용사층의 특성 및 산화거동 This study was performed to investigate the influence of fuel/oxygen ratio (F/O=3.2, 3.0, 2.8) on the characteristics and the oxidation behavior of the hybrid-HVOF sprayed Cr3C2-7wt%NiCr coatings. Decomposition and the oxidation of the Cr3C2was occured during spraying. The degree of transformation from Cr3C2to Cr7C3 was increased with decreasing the F/O ratio. The microstructural differences of the as sprayed coating with F/O ratio can not be distinguished, However, large pores were diminished and then the coatings became dense by heat treatment. Microhardness of the as-sprayed specimen which sprayed with F/O=3.0 condition was hightest (Hv300=1140) and the hardness was increased to 1500 after heat treatment at 600C for 50hrs in air. It was supposed that hardness was increased due to the formation of Cr2O3 within Cr3C2/Cr7C3matrix and the densification of coating layer during heat treatment. Apparent activation energy for oxidation was varied from 21.2 kcalmol1K1 to 23.8 kcalmol1K1 with respect to the F/O ratio. The surface morphology was changed to porous and oxide chusters were grown after oxidation 1000C for 50 hours by the aggressive evolution of gas phase (CrO3 andCO2). The oxide cluster was composed of Ni and Cr.

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Effect of welding condition on microstructures of weld metal and mechanical properties in Plasma-MIG hybrid welding for Al 5083 alloy (알루미늄 5083 합금의 플라즈마 미그 하이브리드 용접시 용접부 미세조직과 기계적 성질 변화에 미치는 용접조건의 영향)

  • Park, Sang-Hyeon;Lee, Hee-Keun;Kim, Jin-Young;Chung, Ha-Taek;Park, Young-Whan;Kang, Chung-Yun
    • Journal of Welding and Joining
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    • v.33 no.1
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    • pp.61-71
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    • 2015
  • The effect of welding condition on microstructure and mechanical property of Plasma-MIG Hybrid Weld between Al 5083 plates(thickness : 10mm) was investigated. 1 pass weld without any defects such as puckering, undercut, and lack of fusion was obtained by 150~200A of plasma current and 5~7mm of welding speed. Gas porosities and shrinkage porosities were existed in the weld near fusion line. As welding speed and plasma current were decreasing, the area fraction of porosity was increasing. The hardness of the weld is increasing as welding speed. On the basis of microstructural analysis, Mg segregated region near dendrite boundaries tends to increase with the welding speed. In the result of hardness test, Distribution of hardness in fusion zone showed little change with the plasma current. However, when the welding speed increased, hardness in weld metal markdly increased. It could be considered that effect of heat input to growth of the dendritic solidification structures. Based on tensile test, tensile properties of weld metal was predominated by area fraction of porosities. Consequently, tensile properties can be controlled by formation site and area fraction of porosity.

Research on Mechanical Properties and Characteristics of Hybrid Composites for Boat (보트에 적용되는 하이브리드 복합재에 대한 기계적 특성 연구)

  • Cho, Je-Hyoung;Kim, Sung-Hoon;Yoon, Sung-Won;Ha, Jong-Rok;Kim, Myung-Hyun
    • Journal of Welding and Joining
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    • v.34 no.2
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    • pp.22-29
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    • 2016
  • Recently, Application of composite materials are increased in transport area for weight reduction. Also, Related technical developments have been implemented actively at domestic and abroad. In particular, The carbon fiber has high strength and ultra light property higher than stainless steel, aluminum, GFRP as Eco-friendly material. Carbon fiber contribute to improving the environmental effect such as fuel saving, expansion of loadage, reducing the exhaustion of carbon dioxide through the weight reduction of transport area. In addition, The carbon fiber is applied to the ship in the area of race yacht, luxury cruise boat as weight reduction and high added-value materials, but there is limited application for general boat because price of carbon fiber is very expensive. For the weight reduction of general boat hull, being used as structure materials, glass fiber and carbon fiber are applied to hull with form of hybrid composite materials, but application of domestic and research for development are incomlete. In this study, An evaluations of mechanical strength property and fatigue strength are performed on composite materials by hybrid weaving of glass fiber and carbon fiber and composite materials forming method by hybrid forming.

Fundamental Study on The Heat Input Model of Hybrid Welding for The Finite Element Analysis (유한요소해석을 위한 하이브리드용접 입열모델 선정에 관한 기초적 연구)

  • 방한서;김영표
    • Proceedings of the KWS Conference
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    • 2003.11a
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    • pp.36-38
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    • 2003
  • In order to understand the basic knowledge on the model of heat source in hybrid welding, authors have conducted finite element analysis to calculate heat distribution using three heat source models of non-split type and split type(Volume, Volume-Volume, Volume-Surface). From the research result, we can confirm that Volume-Volume heat source of split type is suitable for the analysis of heat distribution.

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The Comparison of Thermal Characteristics in FCAW & Hybrid Welded Joint for Fillet Welding of Ship Structure A-Grade Steel (조선용 강재 A-Grade의 Fillet 용접에 대한 FCAW 및 하이브리드 용접부의 열적 특성 비교)

  • O, Jong-In;Park, Ho-Gyeong;Rajesh, S.R.;Jeong, Eun-Yeong;Bang, Han-Seo
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.48-50
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    • 2006
  • Recently many research are going on in the field of application of Laser-Arc hybrid welding for superstructures such as ship-structures, transport vehicles etc. however, the study on heat distribution and welding residual stress of hybrid weld by numerical simulation leaves much to be desired. Therefore a Finite Element based numerical comparison of heat distribution and thermal history in both the FCAW and Hybrid welding been made in this study. Based on this thermal outputs from the present model could be sequentially coupled to suitable mechanical models to predict appropriate mechanical characteristics such as residual stress.

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Effect of Spew fillet on Failure Strength Evaluation in Adhesive Bonded Joints involving Natural Fiber Reinforced Composites (접착제 접합된 자연섬유강화 복합재료의 파괴강도 특성에 미치는 접착제 필릿의 영향)

  • Kim, Yeon-Jik;Yun, Ho-Cheol;Im, Jae-Gyu
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.262-264
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    • 2005
  • This paper is concerned with a fracture strength study of composite adhesive lap joints. The tests were carried out on specimen joints manufactured hybrid stacked joints such as the polyester and bamboo natural fiber layer. The main objective of the work was to test the fracture strength using hybrid fiber composites with a polyester and bamboo natural fiber layer adjacent to the spew fillet of adhesive bonded joints and hybrid stacked joints. The results are presented using tensile-shear strength graph and finite element analysis. The failure mechanisms are discussed in order to explain that spew fillet at the end of the overlap reduces greatly the adhesive shear and effects the tensile-shear strength in hybrid stacked joints.

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Study on the static and fatigue characteristics of the composite hybrid joint with uni-direction fiber orientation (일방향 복합재료 하이브리드 조인트의 정적 및 피로특성에 관한 연구)

  • Kim Byung Chul;Lim Tae Seong;Park Dong Chang;Lee Dai Gil
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.228-231
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    • 2004
  • For the bolted joint of the composite structure, quasi-isotropic stacking is generally used to increase the bearing strength. For the bolted joint of uni-directional composite, the fatigue life limit of the bolted joint can be improved by applying clamping force though the static strength is still very low. In this paper, the static and fatigue characteristics of hybrid joint are investigated which can overcome the disadvantage of the bolted joint of uni-directional composite under static loading by applying adhesive joining. The experimental result shows that the static strength and fatigue life can be improved by applying clamping force to the hybrid joint and the hybrid joint is a good solution for the efficiency of the composite structures.

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Effect of Weldbond Process on the Weldability of 1.2GPa Grade Galvannealed TRIP Steel for Car Body Manufacturing (차체용 1.2GPa급 합금화아연도금 TRIP강의 용접성에 미치는 Weldbond 공정의 효과)

  • Lee, Jong-Dae;Lee, Hye-Rim;Kim, Mok-Soon;Seo, Jong-Deok;Kim, Jun-Ki
    • Journal of Welding and Joining
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    • v.34 no.6
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    • pp.28-34
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    • 2016
  • Galvannealed(GA) steels are now generally used in car body manufacturing for corrosion resistance. In this study, the weldability and joint mechanical behavior of a newly developed 1.2GPa grade GA ultra high strength TRIP(transformation induced plasticity) steel was investigated for three joining processes, such as adhesive bonding, resistance spot welding and weldbonding. Under both shear and peel stress conditions, the failure mode of the adhesive joints were the mixture of the adhesive cohesive failure, adhesive interface failure and coating layer failure. It means that the adhesion strength of GA coating onto the base metal was similar to that of adhesive bonding onto the GA coating. Under the shear stress condition, the weldbonding exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel because the strength of adhesive bond overwhelmed that of the resistance spot weld. Under the peel stress condition, the weldbonding also exerted to expand the optimal spot welding condition of 1.2GPa GA TRIP steel by inducing the tear fracture mode rather than the partial plug fracture mode.