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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
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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
Evaluation and Comparison of Weldabilities with Various Welding Processes on TMCP Steels
Choi, Chul Young ; Ji, Chang Wook ; Kim, Hyoung Chan ; Nam, Dae-Geun ; Kim, Joungdon ; Kim, Soon Kook ; Park, Yeong-Do ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 6~14
DOI : 10.5781/JWJ.2014.32.1.6
This paper has an aim to evaluate microstructure and fracture toughness of TMCP steel weldment applied for off-shore wind tower with the focus on the effect of heat input on the weldment with various welding processes; FCAW(13kJ/cm and 30kJ/cm), SAW(62kJ/cm), and EGW(177kJ/cm). Based on experimental results developed from this study, it was found that the impact toughness of top side for TMCP steel weldments with heat input up to 62 kJ/cm satisfied the required minimum value except the EGW(177kJ/cm). The heat input and microstructure are the main factors of impact toughness. The heat input of 13kJ/cm on back side with low heat input increased the amount of grain boundary ferrite which has low impact toughness, and heat input of 177kJ/cm on top side is significant enough to produce the austenite grain growth. The compositions and sizes of inclusions which are the dominant factors for the formation of acicular ferrite were analyzed by OM and EDS. As the heat input increased, the inclusions also grew and a nucleation site decreased. The size of nonmetallic inclusions and the crack width was nearly similar, therefore the inclusions were related with the crack propagation.
Evaluation on Mechanical Properties with Welding Processes for Off Shore Wind Tower Application
Ji, Changwook ; Choi, Chul Young ; Nam, Dae-Geun ; Kim, Hyoung Chan ; Jang, Jae Ho ; Kim, Ki Hyuk ; Park, Yeong-Do ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 15~21
DOI : 10.5781/JWJ.2014.32.1.15
FCAW(Flux Cored Arc Welding), SAW(Submerged Arc Welding), EGW(Electro Gas Welding), and three-pole SAW are applicable in manufacturing the offshore wind tower. In this paper, mechanical properties of these welded-joints for TMCP steels were evaluated in all above welding processes. The tensile strength of welded-joints for all the welding methods satisfied the standard guideline (KS D 3515). No cracking on weldment was found after the bending test. Changes of weldedments hardness with welding processes were observed. In a weld HAZ (heat-affected zone), a softened HAZ-zone was formed with high heat input welding processes (SAW and EGW). However, the welded-joint fractures were found in the base metal for all cases and small decrease in welded-joint strength was caused by a softened zone. The multi-pole SAW welds exhibited similar mechanical properties comparing to the one with one-pole SAW process.
The Effects of Microstructure on Cold Crack in High-Strength Weld Metals
Lee, Myung-Jin ; Kang, Nam-Hyun ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 22~27
DOI : 10.5781/JWJ.2014.32.1.22
In the past, cold crack was commonly observed in the HAZ(heat affected zone) of high-strength steels. Applying to TMCP(thermo-mechanical controlled process) and HSLA(high strength low alloy) steels, cold crack tends to increase the occurrence in the weld metal. It is generally understood that cold crack occurs when the following factors are present simultaneously : diffusible hydrogen in the weld metal, a susceptible microstructure and residual stress. In particular, many studies investigated the microstructural effect on the cold crack in HAZ and the cold crack in weld metals starts to receive the special attendance in modern times. The purpose of the study is to review the effect of weld microstructures (grain boundary ferrite, Widm
nstatten ferrite, acicular ferrite, bainite and martensite) on cold crack in the weld metals. Among various microstructures of weld metals, acicular ferrite produced the greatest resistance to the cold crack due to the fine interlocking nature and high-angle grain boundary of the microstructure.
Weldability Evaluation in Plasma-GMA Hybrid Welding for Al-5083 Using Analysis of Variance
Jung, Jin Soo ; Lee, Jong Jung ; Lee, Hee Keun ; Park, Young Whan ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 28~33
DOI : 10.5781/JWJ.2014.32.1.28
In this paper, I-butt welding with 6mm thickness using Plasma-GMA welding was carried out. And weld characteristics of the Al-5083 aluminium alloy for Plasma-GMA hybrid welding was evaluated. The orthogonal experimental design was used to investigate the influence of plasma-MIG welding parameters such as plasma current, wire feeding rate, MIG-welding voltage and welding speed on the weld bead geometry and tensile strength using the ANOVA(Analysis of Variation). Then we conducted evaluation of contribution for process parameters. ANOVA results show that bead dimensions are affected by wire feeding speed, welding voltage and welding speed and tensile strength is mainly affected by welding speed and plasma arc current. Tensile strength was decreased by rise in plasma welding current because GMA welding current was decreased by plasma arc.
FSW Properties of Aluminum alloy 5000/6000 for Small Boat
Cho, Je-Hyoung ; Kim, Myung-Hyun ; Choi, Jun-Woong ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 34~39
DOI : 10.5781/JWJ.2014.32.1.34
There are so many difficulties of melt bonding mainly applied for hull construction of a aluminum alloy small boat. For resolving this problem, Friction stir welding(FSW) in non-melting solid state welding Process generally is applied in the transport industry. This paper is studied the joining strength characteristics and macrostructure according to dissimilar aluminium 5000/6000 alloy joining for a small boat applied for this FSW technology. It is reported that difference of joining strength in accordance with the direction of rotation in case of friction stir welding between dissimilar metals(Al/Cu, Al/Fe) is also highly large. In this study, Test is carried out by making the specimen according to the direction of rotation of dissimilar aluminium alloy joining.
Bonding Mechanism and Strength of Metals to Ceramics
Kee, Se-Ho ; Jung, Jae-Pil ; Kim, Won-Joong ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 40~46
DOI : 10.5781/JWJ.2014.32.1.40
Bonding technology and bonding mechanism of metal to ceramic including brazing, diffusion bonding, friction welding and etc were reviewed in this study. Various factors should be considered from a bonding design step to acquire a good bonding joint because of a large difference between metal and ceramic in crystal lattice, coefficient of thermal expansion and various properties. In addition, metal and ceramic bonding technologies are constantly being developed according to precise components, multi-function and application to harsh environment. However, improvement of bonding properties and bonding reliability also should be accompanied. Bonding of ceramics, such as
and SiC, to metals like Ti-alloy, TiAl and steel were described in this paper.
A Study on the Mechanical Properties of Heated Plates by Induction Heating System
Hyun, Chung Min ; Yi, Myung Su ; Cho, Si Hoon ; Jang, Tae Won ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 47~52
DOI : 10.5781/JWJ.2014.32.1.47
Due to of high intensity, lower noise and easy controllability of the heat, induction heating system became well known. Induction heating method has been suggested as substitute for the gas heat source and adopted in the automation of curved hull forming system. In this study, an investigation was accomplished to find the effects on the change of material properties when the induction heating was applied on the mild steel plate. Plates were heated using weaving method to get sufficiently heat affected zone and then cooled with water or in the air. The mechanical properties of the heated plate were evaluated. As results, the tensile test, impact test and microstructures satisfied the class rule.
An Experimental Study on Prediction of Bead Geometry for GTA Multi-pass Welding in Underhead Position
Park, Min-Ho ; Kim, Ill-Soo ; Lee, Ji-Hye ; Lee, Jong-Pyo ; Kim, Young-Su ; Na, Sang-Oh ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 53~60
DOI : 10.5781/JWJ.2014.32.1.53
The automatic arc welding is generally accepted as the preferred joining technique and commonly chosen for assembly of large metal structures such as in areas of automotive, aircraft and shipbuilding due to its joint strength, reliability, and low cost compared to other joint processes. Recently, several mathematical models have been developed and studied for control and monitoring welding quality, productivity, microstructure and weld properties in arc welding processes. This study indicates the prediction of process parameters for the expected welding quality with accordance to the adaptive GTA welding process. Furthermore, the mathematical models is also develop to aid the selection of an optimal welding process as the generation of process controls to predict the bead geometry as a function output parameters in the GTA welding process. The developed models through this study showed comparatively excellent predicted results, and will extend to other welding processes to integrate an optimized system for the robotic welding process.
A Study on the Evaluation of Fatigue Strength of Welded Lap Joint with Element Stress Approach
Kim, Hyeon-Su ; Shin, Sang-Beom ; Kim, Myung-Hyun ; Park, Dong-Hwan ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 61~65
DOI : 10.5781/JWJ.2014.32.1.61
The purpose of this study is to evaluate the applicability of the element stress to establish S-N design curve for the welded lap joint with thin plates below 2mm thickness. In order to do it, the extensive fatigue tests of the welded lap joints with INVAR alloy were performed. With the results, the deign S-N curves for the lap-weld were established by using the reference stresses such as the nominal stress range at the weld throat area, hot spot stress range and element stress range, and compared with regard to the standard deviation. The standard deviation of S-N curves with element stress range was less than that of S-N curves with other reference stresses. In addition, FEA results show the amount of the element stress is less sensitive to mesh size. Based on the results, it can be concluded that the element stress is to be used as the reference stress for the design S-N curves of the welded lap joint.
The Effect of Ti and Sn Contents on the Shear Bonding Strength of Brazing Joint of YSZ to STS430 using Ag Based Filler Metals
Lee, Ki Young ; Park, Hyun Gyoon ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 66~70
DOI : 10.5781/JWJ.2014.32.1.66
In Ti active brazing of YSZ to STS 430 using Ag-Cu Filler Metal, the effect of Ti contents on the shear bonding strength were investigated together with the effect of brazing temperature and holding time. The addition of Ti in Ag-Cu Filler Metal increased the bonding strength up to 4.68% Ti, followed by the decrease with further addition. This seems to be caused by formation of TixOy at the reaction layer. Brazing temperature was optimized at
among a given temperature ranges. The addion of Sn to Ag-Cu filler metal brought the decrease of its melting temperature its melting temperature without a significant decrease of bonging strength.
Effect of Weld Residual Stress on Fatigue Analysis of Nozzle
Kim, Sang-Chul ; Kim, Man-Won ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 71~78
DOI : 10.5781/JWJ.2014.32.1.71
Although the fatigue design curve of ASME Code has enough margin with respect to alternating stress and cycles, the welding residual stress(WRS) should be included in fatigue analysis. In this paper, WRS distribution in a nozzle with dissimilar metal weldment was obtained by finite element analysis and was added in fatigue analysis. The fatigue analysis was performed by following the ASME Code including thermal and stress analysis applying with postulated 30 transient conditions. The calculated results of a cumulative fatigue usage factors(CUF) were compared for the case of the models with or without WRS effects. The results showed that the CUF at weldment and heat affected zone was affected by the WRS.
A Study on Design of Fillet Weld Size for Stiffener in the Hull Bottom of Crude Oil Tanker
Kang, Bong-Gook ; Shin, Sang-Beom ; Park, Dong-Hwan ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 79~86
DOI : 10.5781/JWJ.2014.32.1.79
The purpose of this study is to determine the proper fillet weld size for the stiffeners on hull bottom plate of crude oil tanker. To achieve it, the effective notch stress and hot spot stress of the fillet weld with leg length specified in the rule were evaluated by using comprehensive FE analyses. Based on the results, the fatigue damages at each location of weld were calculated. Meanwhile the transitional behavior of initial welding distortion in the hull bottom plate under the design conditions was investigated by using a non-linear FEA. Welding distortion and residual stress introduced during fabrication process were considered as initial imperfections. According to FE analysis results, if the fillet leg length satisfies the design criteria of the classification society, the concern on the root failure at the fillet welds in the bottom hull plate during the design life can be negligible. In addition, considering the transitional behavior of the distortion during the service life, the fillet leg length should be minimized.
High Current MIG Welding of Al 5083 Alloy under Ar/He Mixed Gas Shielding
Choi, Young-Bae ; Hwang, In-Sung ; Kang, Mun-Jin ; Kim, Dong-Cheol ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 87~92
DOI : 10.5781/JWJ.2014.32.1.87
Recently, use of thick Al 5083 plate has increased in production of LNG storage tank. In general, multi-pass welding has been used to achieve sufficient penetration in thick plate welding. High current welding which enables high deposition and deep penetration is preferred in thick plate welding because the increase of number of pass increases manufacturing cost and formation of weld defect. In this study, welding characteristics according to various Ar/He shielding gas composition was investigated in high current MIG welding. The bead-on-plate welding and V groove welding were conducted on Al 5083 alloy with a thickness of .25 mm. The effect of shielding gas composition on bead shape was evaluated and proper shielding gas composition was proposed. Also arc stability was examined under selected shielding gas composition. One side-one pass welding experiments were conducted for V groove specimen with a thickness of 25 mm. Mechanical properties and hardness profiles were measured for the V groove specimens.
Effect of Heat Input of Outside Weld on Low Temperature Toughness of Inside Weld for Multiple Electrode SA Welded API 5L X70 with Sour Gas Resistance
An, Hyun-Jun ; Lee, Hee-Keun ; Park, Young-Gyu ; Eun, Seong-Su ; Kang, Chung-Yun ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 93~101
DOI : 10.5781/JWJ.2014.32.1.93
This study aims to investigate the effect of heat input of outside SAW weld on low temperature toughness(
) of inside SAW weld for API 5L X70 with sour gas resistance. As increasing heat input of the outside weld, low temperature toughness of the inside weld was decreased. Especially, in spite of the same heat input, the value of low temperature toughness was fluctuated. On the basis of fracture and microstructure analysis, the low temperature toughness is correlated with the fracture area ratio of shear lips and four kinds of fracture sections. These sections were divided with size and shape of dimple correlated with grain boundary ferrite and cleavage correlated acicular and polygonal ferrite in grain. Therefore, it was seen that these sections were two of final solidification area in the inside weld and the outside weld, no reheated zone and reheated zone in the inside weld. In conclusion, it is thought that the difference of low temperature toughness at the same heat input is due to the fact that each of impact test specimens could have the different microstructure, even though the notch was machined under the error tolerance of 1mm. It is because the final solidification area of the inside weld is very narrow.
Development of Digital controlled SCR type CO
Welding System for Implementation Pulse Output
Eun, Jong-Mok ; Choe, Gyu-Ha ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 102~107
DOI : 10.5781/JWJ.2014.32.1.102
welders have widely used for the welding process of heavy industries such as shipbuilding and plant. Since the industrial fields of shipbuilding and plant are usually exposed to severe welding condition with lots of dust, extreme temperature, high humidity and vibration, it is not recommended to use inverter type welder despite its state-of-the-art technology. Many sophisticated functions in the inverter welder may not work due to malfunction of its sensitive components. Hence this study focused on digitalization of SCR
welder by making use of microprocessor for SCR phase control. By this application, fine control of output of the
welding systems is achieved. Also pulse output mode of operation is realized and its verification is carried out with aluminum sample welding. The experimental results showed sound weld bead. The front operation panel provide user with numerical parameter settings and monitors. It will help precise weld process monitoring and control with digital value.
Weldability Increase of Aluminum by Variable Polarity Arc
Cho, Jungho ;
Journal of Welding and Joining, volume 32, issue 1, 2014, Pages 108~111
DOI : 10.5781/JWJ.2014.32.1.108
Low arc weldability of aluminum alloy is enhanced by applying variable polarity TIG and the result is theoretically investigated to figure out the mechanism. Conventionally, it is well known fact that DCEP (reverse polarity) arc is effective on aluminum welding. The reason is due to oxide layer removal by plasma ion bombardment and therefore it is named as cleaning effect. Another fact of polarity characteristic is that DCEN shows higher heat input efficiency therefore conventional variable polarity arc used to apply DCEP portion as small as possible. However, higher DCEP portion shows bigger weldment in this research and it is explained by adopting a theory of arc concentration on oxide layer with tunneling effect which was not clearly mentioned before in several variable polarity TIG welding research. Disagreement between variable polarity TIG welding result and conventional arc polarity theory is rationally explained for the first time with help of electron emission theory.