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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Welding and Joining
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Journal DOI :
The Korean Welding and Joining Society
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Volume & Issues
Volume 34, Issue 4 - Aug 2016
Volume 34, Issue 3 - Jun 2016
Volume 34, Issue 2 - Apr 2016
Volume 34, Issue 1 - Feb 2016
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Effect of Chemical Composition of Nut Material on the Fracture Behavior in Nut Projection Welding of Hot-Stamped Steel Sheet
Lim, Sung-Sang ; Kim, Young-Tae ; Chun, Eun-Joon ; Nam, Ki-Sung ; Park, Young-Wan ; Kim, Jae-Wan ; Lee, Sun-Young ; Choi, Il-dong ; Park, Yeong-Do ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 1~10
DOI : 10.5781/JWJ.2016.34.2.1
The use of materials for modern lightweight auto-bodies is becoming more complex than hitherto assemblies. The high strength materials nowadays frequently used for more specific fields such as the front and rear sub frames, seat belts and seats are mounted to the assembled body structure using bolt joints. It is desirable to use nuts attached to the assembled sheets by projection welding to decrease the number of loose parts which improves the quality. In this study, nut projection welding was carried out between a nut of both boron steel and carbon steel and ultra-high strength hot-stamped steel sheets. Then, the joints were characterized by optical and scanning electron microscope. The mechanical properties of the joints were evaluated by microhardness measurements and pullout tests. An indigenously designed sample fixture set-up was used for the pull-out tests to induce a tensile load in the weld. The fractography analysis revealed the dominant interfacial fracture between boron steel nut weld which is related to the shrinkage cavity and small size fusion zone. A non-interfacial fracture was observed in carbon steel nut weld, the lower hardness of HAZ caused the initiation of failure and allowed the pull-out failure which have higher in tensile strengths and superior weldability. Hence, the fracture load and failure mode characteristics can be considered as an indication of the weldability of materials in nut projection welding.
Pre-processing System for Converting Shell to Solid at Selected Weldment in Shell FE Model
Yoo, Jinsun ; Ha, Yunsok ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 11~15
DOI : 10.5781/JWJ.2016.34.2.11
FE analyses for weldment of ship structure are required for various reasons such as stress concentration for bead tow, residual stress and distortion after welding, and hydrogen diffusion for prediction of low temperature crack. These analyses should be done by solid element modeling, but most of ship structures are modeled by shell element. If we are able to make solid element in the shell element FE modeling it is easily to solve the requirement for solid elements in weld analysis of large ship structures. As the nodes of solid element cannot take moments from nodes of shell element, these two kinds of element cannot be used in one model by conventional modeling. The PSCM (Perpendicular shell coupling method) can connect shell to solid. This method uses dummy perpendicular shell element for transferring moment from shell to solid. The target of this study is to develop a FE pre-processing system applicable at welding at ship structure by using PSCM. We also suggested glue-contact technique for controlling element numbers and element qualities and applied it between PSCM and solid element in automatic pre-processing system. The FE weldment modeling through developed pre-processing system will have rational stiffness of adjacent regions. Then FE results can be more reliable when turn-over of ship-block with semi-welded state or ECA (Engineering critical assessment) of weldment in a ship-block are analyzed.
Characteristic and Measurement Technology of Inner Welding Residual Stresses in Thick Steel Structures
Park, Jeong-ung ; An, Gyu-baek ; Woo, Wanchuck ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 16~21
DOI : 10.5781/JWJ.2016.34.2.16
Recent keywords of the heavy industries are large-scale structure and productivity. Especially, the sizes of the commercial vessels and the offshore structures have been gradually increased to deliver goods and explore or produce oil and natural gas in the Arctic. High heat input welding processes such as electro gas welding (EGW) have been widely used for welding thick steel plates with flux-cored arc welding (FCAW), especially in the shipbuilding industries. Because high heat input welding may cause the detrimental effects on the fracture toughness of the welded joint and the heat affected zone, it is essential to obtain the sufficient toughness of welded joint. There are well known that the fracture toughness like CTOD, CVN, and KIC were very important factors in order to secure the safety of the structures. Furthermore, the welding residual stress should be considered to estimate the unstable fracture in both EGW and FCAW. However, there are no references on the welding residual stress distribution of EGW and FCAW with thick steel plates. Therefore the welding residual stresses were very important elements to evaluate the safety of the welded structure. Based on the measurement results, the characteristics of residual stress distribution through thickness were compared between one-pass electron gas welding and multi-pass flux-cored arc welding. The longitudinal residual stress in the multi-pass flux-cored arc welding is tensile through all thicknesses in the welding fusion zone. Meanwhile, longitudinal residual stress of EGW is tensile on both surfaces and compressive at the inside of the plate. The magnitude of residual stresses by electron gas welding is lower than that by flux-cored arc welding.
Research on Mechanical Properties and Characteristics of Hybrid Composites for Boat
Cho, Je-Hyoung ; Kim, Sung-Hoon ; Yoon, Sung-Won ; Ha, Jong-Rok ; Kim, Myung-Hyun ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 22~29
DOI : 10.5781/JWJ.2016.34.2.22
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.
Effect of Various Factors on the Brazed Joint Properties in Al Brazing Technology
Sharma, Ashutosh ; Lee, Seung Hyun ; Ban, Hyung Oh ; Shin, Young Sik ; Jung, Jae-Pil ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 30~35
DOI : 10.5781/JWJ.2016.34.2.30
Last few decades have seen a rapid increase in the fabrication and characterization of Al alloys for automobiles, heat exchangers and aerospace industries. Aluminium alloys are popular because of their high specific strength, light weight, excellent wear and high oxidation resistance. The development of aluminium alloys in these applications makes their study and research of utmost importance. Brazing is applied to the aluminium alloys for joining various aluminium parts together in most of the industrial applications. Various parameters affect the joining process of these aluminium alloys. In this article, various types of processing parameters have been discussed, and special attention has been given to the category of aluminium brazing alloys. The article reviews on the various parameters that affect the brazing property in various scientific and technological applications.
Recent Study of Technical Development for High Efficient Brazing
Yoo, Ho-Cheon ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 36~45
DOI : 10.5781/JWJ.2016.34.2.36
Recent developing tendency for technologies of high efficient brazing are studied by searching of NDSL, Science Direct, KIPRIS, PCT and so on. Active metal brazing, arc brazing, fluxless brazing, brazing with low melting point, reactive air brazing, laser brazing, laser droplet brazing are investigated. By optimal selecting of the above mentioned technologies, it needs to investigate an economical metallurgical design and the advanced brazing methods. To improve the embrittlement of intermetallic compound at brazing interface, it must be studied the inexpensive variant metals including nonmetals and the heat sources(MIG, TIG, Laser) by hybrid techniques.
Effect of Heating Rates on Microstructures in Brazing Joints of STS304 Compact Heat Exchanger using MBF 20
Kim, Jun-Tae ; Heo, Hoe-jun ; Kim, Hyeon-Jun ; Kang, Chung-Yun ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 46~53
DOI : 10.5781/JWJ.2016.34.2.46
Effect of heating rate on microstructure of brazed joints with STS 304 Printed Circuit Heat Exchanger (PCHE),which was manufactured as large-scale(
, mm), have been studied to compare bonding phenomenon. The specimens using MBF 20 was bonded at
for 1hr with
heating rate, respectively. In case of a heating rate of
, overflow of filler metal was observed at the edge of a brazed joints showing the height of filler metal was decreased from
. At the center of the joints, CrB and high Ni contents of
-Ni was existed. For the joints brazed at a heating rate of
, the height of filler was decreased from
showing the overflow of filler was not appeared. At the center of the joints, only
-Ni was detected gradating the Ni contents from center. This phenomenon was driven from a diffusion amount of Boron in filler metal. With a fast heating rate
, diffusion amount of B was so small that liquid state of filler metal and base metal were reacted. But, for a slow heating rate
, solid state of filler metal due to low diffusion amount of B reacted with base metal as a solid diffusion bonding.
Finite Element Analysis for Design of Divided Shank of Self-Piercing Rivet
Kim, Kwan-Woo ; Kim, Dongbum ; Cho, Hae-Yong ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 54~58
DOI : 10.5781/JWJ.2016.34.2.54
SPR(Self-Piercing rivet) is mechanical element of joining sheet metal components without the need for pre-punched or pre-drilled holes. Newly designed SPR is developed for high joining strength and shearing strength than semi-tubular rivet. In this study, divided shank of self-piercing rivet were designed for joining DP440 and SILAFONT. Newly designed SPR was simulated by using FEM code DEFORM-3D. In simulations of SPR process, various shape of self-piercing rivet were considered for semi-tubular and newly designed SPR. In other to examine the joinability, joining load and lap-shear load of newly designed SPR were compared with semi-tubular by simulated results and experimental ones.
A Study on Development of the Optimization Algorithms to Find the Seam Tracking
Jin, Byeong-Ju ; Lee, Jong-Pyo ; Park, Min-Ho ; Kim, Do-Hyeong ; Wu, Qian-Qian ; Kim, Il-Soo ; Son, Joon-Sik ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 59~66
DOI : 10.5781/JWJ.2016.34.2.59
The Gas Metal Arc(GMA) welding, called Metal Inert Gas(MIG) welding, has been an important component in manufacturing industries. A key technology for robotic welding processes is seam tracking system, which is critical to improve the welding quality and welding capacities. The objectives of this study were to develop the intelligent and cost-effective algorithms for image processing in GMA welding which based on the laser vision sensor. Welding images were captured from the CCD camera and then processed by the proposed algorithm to track the weld joint location. The proposed algorithms that commonly used at the present stage were verified and compared to obtain the optimal one for each step in image processing. Finally, validity of the proposed algorithms was examined by using weld seam images obtained with different welding environments for image processing. The results proved that the proposed algorithm was quite excellent in getting rid of the variable noises to extract the feature points and centerline for seam tracking in GMA welding and could be employed for general industrial application.
Prediction of Tensile Strength for Plasma-MIG Hybrid Welding Using Statistical Regression Model and Neural Network Algorithm
Jung, Jin Soo ; Lee, Hee Keun ; Park, Young Whan ;
Journal of Welding and Joining, volume 34, issue 2, 2016, Pages 67~72
DOI : 10.5781/JWJ.2016.34.2.67
Aluminum alloy is one of light weight material and it is used to make LNG tank and ship. However, in order to weld aluminum alloy high density heat source is needed. In this paper, I-butt welding of Al 5083 with 6mm thickness using Plasma-MIG welding was carried out. The experiment was performed to investigate the influence of plasma-MIG welding parameters such as plasma current, wire feeding rate, MIG-welding voltage and welding speed on the tensile strength of weld. In addition we suggested 3 strength estimation models which are second order polynomial regression model, multiple nonlinear regression model and neural network model. The estimation performance of 3 models was evaluated in terms of average error rate (AER) and their values were 0.125, 0.238, and 0.021 respectively. Neural network model which has training concept and reflects non -linearity was best estimation performance.