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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
Weld Quality Evaluation Method for the Resistance Spot Welds using X-ray Transmission Inspection
Lee, Jong-Dae ; Lee, So-Jeong ; Bang, Jung-Hwan ; Yoon, Gil-Sang ; Kim, Mok-Soon ; Kim, Jun-Ki ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 1~7
DOI : 10.5781/JWJ.2014.32.6.1
For the resistance spot welds of CR1180 and GA1180 TRIP steels, the weld quality evaluation method using the digitalized X-ray transmission imaging apparatus was investigated in comparison with the crosssectional examination method. In the case of the resistance spot welding of CR1180, three circular regions, such as WZ(white zone), GZ(grey zone) and DZ(dark zone), appeared on X-ray image and they corresponded to the diameters of indentation mark, nugget and corona bond, respectively. The variation of X-ray transmission thickness due to the thickness variation of the weld seemed to be mainly responsible for the formation of those contrasts. The X-ray image contrast formed from the variation of transmission thickness at the outer border line of DZ could also enable the inspections of the notch shape, nonuniformity of the welding pressure and spatter from its sharpness, concentricity and the normal straight line, respectively. The X-ray image of the resistance spot weld of galvannealed GA1180 TRIP steel was very similar to that of CR1180 TRIP steel except the crown shaped outer border line of DZ which was considered to be due to the melting behavior of zinc having the boiling temperature even lower than the melting temperature of steel.
A Study on Development of STACO Model to Predict Bead Height in Tandem GMA Welding Process
Lee, Jongpyo ; Kim, IllSoo ; Park, Minho ; Park, Cheolkyun ; Kang, Bongyong ; Shim, Jiyeon ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 8~13
DOI : 10.5781/JWJ.2014.32.6.8
One of the main challenges of the automatic arc welding process which has been widely used in various constructions such as steel structures, bridges, autos, motorcycles, construction machinery, ships, offshore structures, pressure vessels, and pipelines is to create specific welding knowledge and techniques with high quality and productivity of the production-based industry. Commercially available automated arc welding systems use simple control techniques that focus on linear system models with a small subset of the larger set of welding parameters, thereby limiting the number of applications that can be automated. However, the correlations of welding parameters and bead geometry as welding quality have mostly been linked by a trial and error method to adjust the welding parameters. In addition, the systematic correlation between these parameters have not been identified yet. To solve such problems, a new or modified models to determine the welding parameters for tandem GMA (Gas Metal Arc) welding process is required. In this study, A new predictive model called STACO model, has been proposed. Based on the experimental results, STACO model was developed with the help of a standard statistical package program, MINITAB software and MATLAB software. Cross-comparative analysis has been applied to verify the reliability of the developed model.
Prediction of Cr Content in the Martensitic-hardfaced Weldment Utilizing Dilution Rate Analytically Estimated
Kim, Bong-Hun ; Kim, Chun-Hwan ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 14~21
DOI : 10.5781/JWJ.2014.32.6.14
High-temperature corrosion resistance of martensitic-hardfaced weldment is generally evaluated by the Cr content depending on dilution rate. Present study used a commercial program(SYSWELD) applying three-dimensional heat flow analysis to predict temperature distribution of weld. Configuration of weld bead can be determined by the contour of melting temperature and simultaneously dilution rate is calculated to predict Cr content. Experimental study also has been conducted to measure Cr content of harfaced surface welded by FCAW. Results indicated that computational results were well matched with those obtained from experiments.
Influence of Surface Roughness of Tools on the Friction Stir Welding Process
Hartmann, Michael ; Bohm, Stefan ; Schuddekopf, Sven ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 22~28
DOI : 10.5781/JWJ.2014.32.6.22
Most publications on friction stir welding describe phenomena or results with given process parameters like feed rate, rotation speed, angle and depth of penetration. But without a complete documentation of tool design, the results under the same process parameters are completely different. For this purpose, the Institute of Cutting and Joining Manufacturing Processes (tff), University of Kassel investigated the influence of tool roughness on the friction stir welding process. Therefore a defined surface finish was produced by turning and die sinking. As basis of comparison the constant parameters were rotation speed, feed rate, tilt angle and a heel plunge depth. Sound butt-welds were produced in aluminium alloy 6082 (AlMgSi1) with 1.5 mm sheet thickness with a turned reference tool with a surface of
in position controlled mode. The surfaces are manufactured from a very fine to a very rough structure, classified by the VDI-classes with differences in the arithmetical mean roughness. It can be demonstrated with the help of temperature measures, that less heat is generated at the surfaces of the shoulder and the pin by the higher roughness due to lower active friction contact surface. This can also be seen in the resulting wormhole defects.
Effects of C on the Strength and Toughness of FCAW Weld Metal of YS 460 MPa Steels for Ship and Offshore Structures
Jeong, Sang-Hoon ; Eom, Jeong-Ho ; Choi, Han-Geul ; Jeong, Byung-Ho ; Hur, Sung-Hwa ; Kang, Chang-Yong ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 29~34
DOI : 10.5781/JWJ.2014.32.6.29
This paper has an purpose to study the effect of C on the toughness of YS 460 MPa FCAW weld metal. These effects were evaluated by charpy impact and CTOD test about 4 FCAW weld metal containing various C and Si content in relation to microstructure. Increase of C content was helpful to increase AF volume fraction and reduce PF(G) and FS volume fraction by increasing super cooling rate for ferrite transformation. Also, Increase of C content up to 0.045wt% made the strength and impact toughness higher by increasing AF volume fraction. The weld metal containing higher C content indicated higher CTOD value. It is because the volume fraction of PF(G) and FS, can play a role as crack initiation site, was reduced. Effect of C on the strength and elongation of weld metal was higher with an increase of Si contents.
Evaluation of Gas Metal Arc Welding Characteristics according to Contact Tip Materials
Kim, Dong Yoon ; Hwang, In Sung ; Kim, Dong Cheol ; Kang, Moon Jin ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 35~40
DOI : 10.5781/JWJ.2014.32.6.35
The contact tip for gas metal arc welding has important functions to transmit the welding current to the wire and to guide the wire to molten pool. If the contact tip is damaged, it is a cause of lowering the welding productivity due to removal of welding defects and replacement of contact tip. In case of the use of a contact tip for a long time the arc is unstable because the processed hole in the contact tip center is larger, and the variation of aiming position of the welding wire causes a seam tracking error. In this study, gas metal arc welding experiments using contact tip of three different materials were performed. The contact tips with Cu-P, Cu-Cr, and Cu-ODS were used at the experiments, and the welding characteristics by each contact tip were evaluated. After welding contact tip appearance, welding spatter adhesion amount of the nozzle, and weld bead appearance were evaluated. The welding current and welding voltage were measured to verify arc stability during arc welding.
Cracking Susceptibility of Laser Cladding Process with Co-Based Metal Matrix Composite Powders
Lee, Changmin ; Park, Hyungkwon ; Lee, Changhee ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 41~46
DOI : 10.5781/JWJ.2014.32.6.41
In this study, cracking susceptibility of laser cladding was investigated according to the processing parameters such as laser power, scan speed and feeding rate with blended powders of stellite#6 and technolase40s (WC+NiCr). The solidification microstructure of clad was composed of Co-based dendrite structures with
eutectic phases at the dendritic boundaries. The crack propagation showed transgranular fracture along dendritic boundaries due to brittle chrome carbide at the eutectic phases. From results of fractography experiments, the fracture surface was typical cleavage brittle fracture in the clad and substrate. The number of clad cracks, caused by a tensile stress after the solidification, increased with increase of laser power, scan speed and feeding rate. Increase of the laser power caused large pores by facilitating WC decarburizing reaction. And the pores affected increase of crack susceptibility. High scan speed caused increment of clad cracks due to thermal stress and WC particle fractures. Also, increase of the feeding rate accompanied an amount of WC particles causing crack initiation and decarburizing reaction.
Effects of GTAW Pulse Condition on Penetration, Discoloration and Bending Property for Titanium Tube
Min, Seonghwan ; An, Sungyong ; Park, Jitae ; Park, Youngdo ; Kang, Namhyun ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 47~55
DOI : 10.5781/JWJ.2014.32.6.47
The purpose of the study is to produce a mechanically improved weld and minimum variation of color through comparing unpulsed and pulsed GTAW (Gas Tungsten Arc Welding) for pure titanium (CP grade7) tube. Pulsed GTAW using 60 A peak current and 20 A background current (1:9) achieved the wider window of welding conditions having part and full penetration without burn-through than the case of unpulsed GTAW. Moreover, the pulsed welding reduced a discoloration on the back bead of the weld and the size of microstructures (basket weave and serrated
). That is because the pulsed welding has it's a low heat input and severe weld flow induced from electric current variation. Furthermore, the pulsed welding improved the bending property of the welded Ti tube. The enhanced bending property for the pulsed GTAW was due to the insignificant discoloration on the weld surface with maintaining the metal polish.
A Study on the Characteristic of Weld Joint and Tensile Fracture of SUS304 and Cu High-Speed Dissimilar Lap Welds by Single Mode Fiber Laser
Lee, Su-Jin ; Kim, Jong-Do ; Katayama, Seiji ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 56~63
DOI : 10.5781/JWJ.2014.32.6.56
To develop and understand dissimilar metals joining of Stainless steel and Copper, ultra-high speed laser lap welding was studied using single mode fiber laser in this study. SUS304 and Cu have large differences in materials properties, and Cu and Fe have no intermetallic compounds by typical binary phase of Cu and Fe system. In this study, ultra-high speed lap welds of SUS304 and Cu dissimilar metals using single-mode fiber laser was generated, and weldability of the weld fusion zone was evaluated using a tensile shear test. To understand the phenomenon of tensile shear load, weld fusion zone of interface weld area and fracture parts after tensile shear test were observed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis system. And it was confirmed that Cu was easily melting and penetrating in the grain boundaries of SUS304 because of low melting temperature. And high thermal conductivity of copper occurred dissipate heat energy rapidly. These properties cause the solidification cracking in weld zone.
A Study on Correlationship between the Induced Plasma and Emission Signals for In-process Monitoring in Stainless Steel Welding of Fiber Laser (I) - Properties Changes of the Measured Signals in a Thin Plate Welding -
Lee, Chang-Je ; Kim, Jong-Do ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 64~69
DOI : 10.5781/JWJ.2014.32.6.64
The applications by using fiber laser have increased recently. However, due to high beam quality of fiber laser, it is inappropriate to apply the existing laser welding monitoring technology to the fiber laser welding as it is. On this study, thus, we analyzed emission signal with RMS and FFT for the in-process monitoring during fiber laser welding. 12mm-thick 304L stainless steel sheet was used in fiber laser welding and the result showed as follows: The intensity changes in RMS did not clarify the distinction between full penetration and partial penetration. However, as welding speed increases, specific frequency also increases in regards of frequency analysis by using FFT.
A Study on Correlationship between the Induced Plasma and Emission Signals for In-process Monitoring in Stainless Steel Welding of Fiber Laser (II) - Properties Changes of the Measured Signals in a Thick Plate Welding -
Lee, Chang-Je ; Kim, Jong-Do ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 70~74
DOI : 10.5781/JWJ.2014.32.6.70
On this study, we researched the in-process monitoring during fiber laser welding as well as on the first paper. On the previous/formal study, we analyzed the change of emission signal on thin plate welding. On this study, however, we analyzed RMS and FFT with emission signals in laser welding on lap joint and butt joint of 8mm-thick 316L stainless steel. As the result, the movement of specific frequency peak was observed according to welding speed changes. Furthermore, frequency peak as a result of FFT on the thick plate welding are much clearer than on the thin plate welding. Therefore, it is expected that the welding parameter changes can be predicted in case of applying FFT to in-process monitoring.
Degradation Behavior of Eutectic and Pb-free Solder Plated Ribbon in Crystalline Silicon Photovoltaic Module
Kim, Ju-Hee ; Kim, A Yong ; Park, Nochang ; Ha, Jeong Won ; Lee, Sang Guon ; Hong, Won Sik ;
Journal of Welding and Joining, volume 32, issue 6, 2014, Pages 75~81
DOI : 10.5781/JWJ.2014.32.6.75
Usage of heavy metal element (Pb, Hg and Cd etc.) in electronic devices have been restricted due to the environmental banning of the European Union, such as WEEE and RoHS. Therefore, it is needed to develop the Pb-free solder plated ribbon in photovoltaic (PV) module. This study described that degradation characteristics of PV module under damp heat (DH,
and 85% R.H.) condition test for 1,000 h. Solar cell ribbons were utilized to hot dipping plate with Pb-free solder alloys. Two types of Pb-free solder plated ribbons, Sn-3.0Ag-0.5Cu (SAC305) and Sn-48Bi-2Ag, and an electroless Sn-40Pb solder hot dipping plated ribbon as a reference sample were prepared to evaluate degradation characteristics. To detect the degradation of PV module with the eutectic and Pb-free solder plated ribbons, I-V curve, electro-luminescence (EL) and cross-sectional SEM analysis were carried out. DH test results show that the reason of maximum power (Pm) drop was mainly due to the decrease fill factor (FF). It was attributed to the crack or oxidation of interface between the cell and the ribbon. Among PV modules with the eutectic and Pb-free solder plated ribbon, the PV module with SAC305 ribbon relatively showed higher stability after DH test than the case of PV module with Sn-40Pb and Sn-48Bi-2Ag solder plated ribbons.