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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Welding and Joining
Journal Basic Information
Journal DOI :
The Korean Welding and Joining Society
Editor in Chief :
Volume & Issues
Volume 32, Issue 6 - Dec 2014
Volume 32, Issue 5 - Oct 2014
Volume 32, Issue 4 - Aug 2014
Volume 32, Issue 3 - Jun 2014
Volume 32, Issue 2 - Apr 2014
Volume 32, Issue 1 - Feb 2014
Selecting the target year
A Development of Overlay GTAW Welding System for Pipe Inside Straight Process
Eun, Jong-Mok ; Lee, Young-Kyu ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 4~8
DOI : 10.5781/JWJ.2014.32.2.4
In this research, GTA overlay welding system is developed for inside of straight pipes in various diameter. It can be applied to oil, ship building and plant industry, especially pipes connected to pressure vessels, for the purpose of cost reduction by cladding inside of pipes with corrosion and heat resistant alloys such as stainless steel or Inconel. Developed system consists of GTA power source, torch, wire feeding system, automatic arc length adjusting device, CCD camera and cooling unit. Two types of pipe inside overlay welding system are developed. One is for maximum 3m pipe length with 3 inch ~ 12 inch pipe outer diameter. Another type can be applied to maximum 12m pipe length with 7 ~ 24 inch OD. Developed system successfully produced inside cladded pipe and the results are shown through cross sectional images of the pipes.
Friction Stir Welding of 900MPa Grade TWIP Steel
Lee, Kwang-Jin ; Kim, Sang-Hyuk ; Kwon, Eui-Pyo ; Son, Kyu-Song ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 9~13
DOI : 10.5781/JWJ.2014.32.2.9
Friction stir welding (FSW) was successfully performed about 900MPa grade Twinning Induced Plastisity (TWIP) steel. A PCBN tool with convex-type shoulder was applied. Optimal process conditions were deduced. Microstructure and mechanical properties such as hardness, tensile strength and impact absorbed energy were observed and evaluated, respectively. An optical microscope (OM) and a field emission scanning electron microscope (FE-SEM) was selected for observing the grain structure.
Friction Stir Welding of Ferritice Stainless Steel
Ahn, Byung-Wook ; Choi, Don-Hyun ; Yeon, Yun-Mo ; Jung, Seung-Boo ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 14~17
DOI : 10.5781/JWJ.2014.32.2.14
Ferritic stainless steels are widely used in the construction industry and in exhaust manifolds due to their low cost and relatively superior stress corrosion cracking resistance and pitting corrosion resistance compared to austenite stainless steels. Ferritic stainless steels are currently welded by various welding process including gas tungsten arc welding (GTAW), electron resistance welding (ERW) and laser beam welding. However, when these stainless steels are welded by fusion welding, some problems occur in the fusion zone (FZ) and heat affected zone (HAZ). First, the ductility of the weld is reduced due to the grain growth in the FZ and HAZ. Second, as its HAZ is frequently sensitized during welding, corrosion resistance deteriorates in this region due to the Cr depletion zone. To prevent these problems, it is recommended that ferritic stainless steels be welded with a low heat input. In this study, recent researches in the view of friction stir welded ferritic stainless steels are briefly reviewed.
Effect of Preheat Temperature on Diffusible Hydrogen Content in Weld Metal Deposited using Flux Cored Wire
Kim, Dong Yoon ; Hwang, In Sung ; Kim, Dong Cheol ; Kang, Moon Jin ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 18~21
DOI : 10.5781/JWJ.2014.32.2.18
Cold cracking of weldment is one of the most serious welding problems. A sufficient quantity of diffusible hydrogen, a residual stress, and a sensitive microstructure are the causes of cold cracking. Removal of any one of these factors can be used to prevent cold cracking. Application of flux cored arc welding process is increasing due to high productivity and easiness of welding. In addition, to prevent cold cracking in the HAZ or weldment, preheat temperature and interpass temperature have to be controlled. In this study, the effect of preheat temperature on the levels of diffusible hydrogen in the weld metal deposited using flux cored wire was examined. The levels of preheat temperature of base metal specimen were ambient temperature, 50, 100 and
respectively. The result showed that the increase of preheat temperature was a linear relationship with reduction of diffusible hydrogen content in weldment.
An Experimental Study on Optimizing for Tandem Gas Metal Arc Welding Process
Lee, Jongpyo ; Kim, Illsoo ; Lee, Jihye ; Park, Minho ; Kim, Youngsoo ; Park, Cheolkyun ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 22~28
DOI : 10.5781/JWJ.2014.32.2.22
To enhance productivity and provide high quality production material in a GMA welding process, weld quality, productivity and cost reduction affects the number of process variables. In addition, a reliable welding process and conditions must be implemented to reduce weld structure failure. In various industries the welding process mathematical model is not fully formulated for the process parameter and on the welding conditions, therefore only partial variables can be predicted. The research investigates the interaction between the welding parameters (welding speed, distance between electrodes, and flow rate of shielding gas) and bead geometry for predicting the weld bead geometry (bead width, bead height). Taguchi techniques are applied to bead shape to develope curve equation for predicting the optimized process parameters and quality characteristics by analyzing the S/N ratio. The experimental results and measured error is within the range of 10% presenting satisfactory accuracy. The curve equation was developed in such a way that you can predict the bead geometry of constructed machinery that can be used for making tandem welding process.
δ-Ferrite Behavior of Butt Weld Zone in Clad Steel Plates Depended on Holding Time of PWHT
Park, Jae-Won ; Lee, Chul-Ku ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 29~36
DOI : 10.5781/JWJ.2014.32.2.29
Recently, in order to enhance the function and usefulness of products, cladding of dissimilar materials that maximizes the performance of the material is being widely used in all areas of industry as an important process. Clad steel plate, produced by cladding stainless steel plate, an anticorrosive material, on carbon steel plate, is being used to produce pressure vessels. Stainless steel plate has good corrosion resistance, and carbon steel plate has good rigidity and strength; clad steel can satisfy all of these qualities at once. This study aims to find the
-ferrite behavior, mechanical properties, structure change, integrity and reliability of clad steel weld on hot rolled steel plates. For this purpose, multi-layer welding, repair welding and post weld heat treatment were implemented according to welding procedure specifications (WPS). In order to observe the mechanical properties and toughness of clad steel weld zone, post weld heat treatment was carried out according to ASME Sec. VIII Div.1 UW-40 procedure for post weld heat treatment. With heat treatment at
, the hold time was used as the process variable, increased by intervals that were doubled each time, from 80 to 1,280 min. The structure of weld part was typical cast structure; localized primary austenite areas appeared near central vermicular ferrite and fusion line. The heat affected zone showed rough austenite structure created by the weld heat input. Due to annealing effects of heat treatment, the mechanical properties (tensile strength, hardness, impact value) of the heat affected area tended to decrease. From the results of this study, it is possible to conclude the integrity of clad steel welds is not affected much in field welding, repair welding, multi-layer welding, post weld heat treatment, etc.
A Study of the Thickness Effect using Structural Stress Approach for Fillet Welded Joints
Xin, Wen-Jie ; Oh, Dong-Jin ; Kim, Myung-Hyun ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 37~42
DOI : 10.5781/JWJ.2014.32.2.37
In this study, non-load-carrying fillet welded joints fabricated using EH grade-steel are evaluated with the structural stress approach. The thickness effect was investigated by a study on welded steel joints with thickness ranging from 25 to 80mm. As-welded joint for main plate thickness of 25 to 80mm, the fatigue strength is reduced gradually. On the other hand, in case of main plate thickness of 25 to 80mm, the structural stress concentration factor increases gradually. As a result, for structural stress approach, thickness effect is not required for correction. Based on these results, a new evaluation fillet welded joint for fatigue design purposes has been proposed FAT 125.
Proper Arc Welding Condition Derivation of Auto-body Steel by Artificial Neural Network
Cho, Jungho ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 43~47
DOI : 10.5781/JWJ.2014.32.2.43
Famous artificial neural network (ANN) is applied to predict proper process window of arc welding. Target weldment is variously combined lap joint fillet welding of automotive steel plates. ANN's system variable such as number of hidden layers, perceptrons and transfer function are carefully selected through case by case test. Input variables are welding condition and steel plate combination, for example, welding machine type, shield gas composition, current, speed and strength, thickness of base material. The number of each input variable referred in welding experiment is counted and provided to make it possible to presume the qualitative precision and limit of prediction. One of experimental process windows is excluded for predictability estimation and the rest are applied for neural network training. As expected from basic ANN theory, experimental condition composed of frequently referred input variables showed relatively more precise prediction while rarely referred set showed poorer result. As conclusion, application of ANN to arc welding process window derivation showed comparatively practical feasibility while it still needs more training for higher precision.
Heat Treatment Effect on Super Duplex Stainless Steel UNS S32750 FCA Multipass Welds
Jang, Bok-Su ; Moon, In-June ; Lim, Myung-Jin ; Kim, Se-Cheol ; Kim, Soo-Sung ; Lee, Jung-Won ; Park, Hai-Woong ; Koh, Jin-Hyun ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 48~53
DOI : 10.5781/JWJ.2014.32.2.48
This study was carried out to investigate the effect of postweld heat treatment(PWHT, 930, 1080,
) on the microstructure, phase formation, pitting corrosion and mechanical properties such as hardness, tensile strength and impact values of super duplex stainless steel(UNS S32750) multipass welds. Based on the microstructural examination and X-ray diffraction analysis, it was found that the
phase was formed in the welds heat treated at
in which the ferrite content greatly decreased into 5~10% in the welds. The secondary austenite was formed in the reheated zone of welds and redissolved into ferrite with increasing heat treatment temperatures. The tensile strength and impact values of welds heat treated at
were the lowest and revealed the brittle fracture surface. The weight loss by pitting corrosion increased with test temperatures. It was confirmed that pitting corrosion occurred mainly in secondary austenite of reheated zones. The postweld heat treatment temperature is recommended to be in the range of
Analysis of Strengthening Structures of Steel Manhole Cover
Kim, Heung-Kyu ; Yang, Young-Soo ; Bae, Kang-Yul ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 54~62
DOI : 10.5781/JWJ.2014.32.2.54
Manhole cover, which is usually made of grey cast iron and consists of frame and cover, should have enough strength to support the heavy traffic load. The manhole cover made of cast iron has heavy weight to handle manually and is vulnerable to impact force with its brittle characteristics. Moreover, its production process of casting has been regulated in terms of environmental pollution. In this study, steel manhole cover is proposed to substitute the cast cover with a series of structural analyses to confirm its strength to support the test load for manhole cover. The cover of the proposed steel manhole cover is made of thin circular pate and stiffeners below the plate. Rectangular columns and hollow circular plate were selected for the shape of the stiffener. In order to give enough strength for the cover to behave within elastic range in the loading, strengthening structures of the cover were varied with increasing the number and the size of the stiffeners. The results of the analyses revealed that when both the hollow circular stiffener and cross stiffeners were additionally applied at the same time to the steel cover with longitudinal stiffeners, the maximum stress level in the cover could be reduced to that level presented in the cast cover.
Laser Energy Optimization for Dissimilar Polymer Joining
Song, Chi Hun ; Choi, Hae Woon ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 63~69
DOI : 10.5781/JWJ.2014.32.2.63
Dual laser heat sources were used for polymer based material joining. An infrared camera and thermocouple DAQ system were used to correlate the temperature distribution to computer simulation. A 50 degree tilted pre-heating laser source was acting as a heating source to promote the temperature to minimize thermal shock by the following a welding heat source. Based on the experimental result, the skin depth was empirically estimated for computer simulation. The offsets of 3mm, 5mm and 10mm split by weld and preheat were effectively used to control the temperature distribution for the optimal laser joining process. The closer offset resulted in an excessive melting or burning caused by sudden temperature rising. The laser power was split by 50%, 75% and 100% of the weld power, and the best results were found at 50% of preheating. To accurately simulate the physical laser beam absorption and joining optical properties were experimentally measured for the computer FEM simulation. The simulation results showed close correlation between theoretical and experimental results. The developed dual laser process is expected to increase productivity and minimize the cost for the final products.
Resistance Spot Welding Characteristics of Mg Alloy Applying Current Waveform Control
Choi, Dong-Soon ; Hwang, In-Sung ; Kim, Dong-Cheol ; Ryu, Jae-Wook ; Kang, Moon-Jin ;
Journal of Welding and Joining, volume 32, issue 2, 2014, Pages 70~75
DOI : 10.5781/JWJ.2014.32.2.70
In automotive industry, applying of Mg alloy to autobody has been issued recently as a light metal. But poor resistance spot weldability of Mg alloy is blocking commercialization. So studies on improving resistance spot weldability of Mg alloy is increasing continuously. For reduce loss of heat input during welding, inverter DC power source is considered because of short rise time to target welding current. But rapid rising of welding current can increase temperature rapidly in nugget and oxide film between electrode and base metal, and that causes generating expulsion on low welding current range. In this study, for increase optimum welding current range and prevent generating expulsion, applicate various types of welding current waveform controls during resistance spot welding. For analysis effects of each current waveform control, acceptable welding current regions according to electrode force and welding time is determined and lobe diagram is derived. In result, pre heat is proposed as optimum type of welding current waveform control.