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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Welding and Joining
Journal Basic Information
Journal DOI :
The Korean Welding and Joining Society
Editor in Chief :
Volume & Issues
Volume 19, Issue 6 - Dec 2001
Volume 19, Issue 5 - Oct 2001
Volume 19, Issue 4 - Aug 2001
Volume 19, Issue 3 - Jun 2001
Volume 19, Issue 2 - Apr 2001
Volume 19, Issue 1 - Feb 2001
Selecting the target year
Measurement of Voltage and Current in Fusion Welding
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 252~254
Characteristics of Weld Quality Produced by the High Frequency Electric Resistance Welding Simulator
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 255~260
ERW Steel Pipe for Natural Gas Pipeline
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 261~266
Weld Defect Formation Phenomena during High Frequency Electric Resistance Welding
Choi, Jae-Ho ; Chang, Young-Seup ; Kim, Yong-Seog ;
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 267~273
In this study, welding phenomena involved in formation of penetrators during high frequency electric resistance welding were investigated. High speed cinematography of the process revealer that a molten bridge between neighboring skelp edges forms at apex point and travels along narrow gap toward to welding point at a speed ranging from 100 to 400 m/min. The bridge while moving along the narrow gap swept away oxide containing molten metal from the gap, providing oxide-free surface for a forge-welding at upsetting stand frequency of the budge formation, travel distance and speed of the bridge were affected by the heat input rate into strip. The travel distance and its standard deviation were found to have a strong relationship with the weld defect density. Based on the observation, a new mechanism of the penetrator formation during HF ERW process is proposed.
Analysis of High Frequency Resistance Welding
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 274~277
A Study on High Temperature Crack Growth Behavior in 2.25Cr-lMo Steel Weldments at
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 278~284
Both creep deformation and creep crack growth experiments have been conducted on 2.25Cr-1Mo steel weldment in order to provided an information on residual life prediction of structural component weldment containing a crack. The stress exponent of creep deformation equation for the base metal and weldment at 823k were found to be 10.2 and 7.3, respectively. These two values could be assumed that dislocation climb processes are controlling the creep deformation of both materials. The creep rate of the weldment was very low, compared with that of base metal under the same applied stress. Whereas the creep crack growth rate of the weldment was almost twice higher than that of base metal under the fixed value of
. This may indicate that the weldment is stronger than the base metal in view of creep deformation and is brittle during creep crack growth due to the intrinsic microstructure of banite and relatively higher and Mn contents.
A Study on the Stress Distribution of Steel Water Pipes(I) - Characteristics of Residual Stress Distribution by PWHT -
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 285~291
Large steel water pipes are joined prevalently by the bell end method, and are welded both at inside and outside of lapped parts. In practice, welded joints of water pipes are very critical, because in most cases failure of pipes causing leakage occurs at the welded joint. Therefore some methods have been developed to ensure the soundness of welded joints of water pipes, like leakage tests and nondestructive tests (NDTs). But one of the major characteristics that affects the soundness of welded Joints is the stress distribution caused by welding and external forces. Some studies have been carried out on the residual stress of steel water popes, but complex stress distributions by welding and external forces are rarely studied. In this study, temperature and stress distributions in steel water pipes produced by welding are predicted by a three-dimensional finite element method(FEM). Also, stress values are measured from real steel water pipes by the hole-drilling methods, and compared with predicted ones. The influence of some typical post weld treatments on residual stress distribution was also investigated by residual stress measurements.
A Study on the Stress Distribution of Steel Water Pipes(II) - Characteristics of Stress Distribution by External Forces and PWHT -
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 292~297
One of the major characteristics that affects the life of welded steel water pipes is the stress distribution caused by welding and external forces. Some studios have bean carried out on the residual stress of steel water pipes. But the results on the stress distributions by welding and complex external forces are rare, because real water pipes operate under the ground and many kinds of external forces act simultaneously on the joints. To understand the complex stress distributions of welded joints, therefore predictions by numerical or analytic methods are required. In this study, temperature and stress distributions in steel water pipes produced by welding are predicted by a three-dimensional finite element method(FEM). Based on these results, stress distributions by welding and complex external forces are evaluated by adopting the same numerical method. The influence of some post weld heat treatments on residual stress distributions is also investigated.
A Study on Failure Analysis of Low Pressure Turbine Blade Subject to Fatigue Load
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 298~304
Turbine blade is subject to force of three types ; the torsional force by torsional mount, the centrifugal force by the rotation of rotor and the cyclic bending force by steam pressure. The cyclic bending force was a main factor on fatigue strength. SEM fractography in root of turbine blade showed micro-clack width was not dependent on stress intensity factor range. Especially, fatigue did not exist on SEM photograph in root of turbine blade. To clear out the fracture mechanism of turbine blade, nanofractography was needed on 3-dimensional crack initiation and crack growth with high magnification. Fatigue striation partially existed on AFM photograph in root of turbine blade. Therefore, to find a fracture mechanism of the torsion-mounted blade in nuclear power plant, the relation between stress intensity factor range and surface roughness measured by AFM was estimated, and then the load amplitude ΔP applied to turbine blade was predicted exactly by root mean square roughness.
A Study on the Fluxless Bonding of Si-wafer/Solder/Glass Substrate
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 305~310
UBM-coated Si-wafer was fluxlessly soldered with glass substrate in
atmosphere using plasma cleaning method. The bulk Sn-37wt.%Pb solder was rolled to the sheet of
thickness in order to bond a solder disk by fluxless 1st reflow process. The oxide layer on the solder surface was analysed by AES(Auger Electron Spectroscopy). Through rolling, the oxide layer on the solder surface became thin, and it was possible to bond a solder disk on the Si-wafer with fluxless process in
gas. The Si-wafer with a solder disk was plasma-cleaned in order to remove oxide layer formed during 1st reflow and soldered to glass by 2nd reflow process without flux in
atmosphere. The thickness of oxide layer decreased with increasing plasma power and cleaning time. The optimum plasma cleaning condition for soldering was 500W 12min. The joint was sound and the thicknesses of intermetallic compounds were less than
A Study on the Initial Bonding Strength of Solder Ball and Au Diffusion at Micro Ball Grid Array Package
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 311~316
This paper presents that the affecting factors to the solderability and initial reliability. It is the factor that the coefficient of thermal expansion between package and PCB(Printed Circuit Board), the quantity of solder paste and reflow condition, and Au thickness of the solder ball pad on polyimide tape. As the reflow soldering condition for 48
is changed, it is estimated that the quantity of Au diffusion at eutectic Sn-Pb solder surface and initial bonding strength of eutectic Sn-Pb solder and lead free solder. It is the result that quantitative measurement of Au diffusion quantity is difficult, but the shear strength of eutectic Sn-Pb solder joint is 842 mN at first reflow and increases 879 mN at third reflow. The major failure mode in solder is judged solder fracture. So, Au diffusion quantity is more affected by reflow temperature than by the reflow times.
Effect of Process Parameters on Bead Formation in Nd:YAG Laser Welding of Thin Steels
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 317~324
This study deals with high power Nd:YAG laser welding of thin steels for small pressure vessels. Full penetration welding at the overlap joint was performed so as to assure sufficient weld strength. Results showed that mid-depth weld size reduced drastically with increasing the travel speed. Position of focus had little effect on the bead formation even though short focal system was used. However, the shape factor and the bead width had closely related with the position of focus. Based on the microstructural inspection, acceptable weld was obtained when the overlap clearance was controlled up to 20% of the base metal thickness. In the case that the joint contained more clearance than the critical value, both the tensile shear strength and the tear strength were reduced. Results also demonstrated that shielding gases were proved to play a key role as far as the bead formation characteristics was taken into consideration. Blowing dry air through 5mm in diameter nozzle produced narrower bead cross-section than that of argon or nitrogen shielding.
The Effect of Base Metal Grain Boundary on Isothermal Solidification Phenomena during TLP Bonding of Ni Base Superalloys
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 325~333
The effect of base metal grain size on isothermal solidification behavior of Ni-base superalloy, CMSX-2 during transient liquid phase (TLP) bonding was investigated employing MBF-80 insert metal. TLP-bonding of single crystal. coarse-grained and fine-grained CMSX-2 was carried out at 1373∼1548k for various holding time in vacuum. The eutectic width diminished linearly with the square root of holding time during isothermal solidification process for single crystal, coarse-grained and fine-grained base metals. The completion time for isothermal solidification decreased in the order ; single crystal, coarse-grained and fine-grained base metals. The difference of isothermal solidification rates produced when bonding the different base metals could be explained quantitatively by the effect of base metal grain boundaries on the apparent average diffusion coefficient of boron in CMSX-2.
A Study on Flow-Accelerated Corrosion of SA106 Gr.C Weldment
Zheng Yugui ;
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 334~341
The chemical and geometric effects of weld on flow-accelerated corrosion (FAC) of SA106 Gr.C low alloy steel pipe in 3.5wt% NaCl and simulated feedwater of nuclear power plant have been investigated by using rotating cylinder electrode. Polarization test and weight loss test were conducted and compared at rotating speed of 2000rpm (3.14m/s) with the variables of chemical and geometric parameters. The results showed that the chemical effects were relatively larger than the geometric effects, and the welded parts were the local anode and preferentially corroded, which could be explained by the differences between microstructural and compositional parameters. On the other hand, under active corrosion conditions, the heat affected zone were severely corroded and microstructural effects became the important role in the whole process.
Stress Distribution and Strength Evaluation of Adhesive Bonded Single-lap Joints
Journal of Welding and Joining, volume 19, issue 3, 2001, Pages 342~347
Recently, adhesive-bonding technique is wifely used in manufacturing structures. Stress and strain analysis of joints are essential to design adhesive-bonded joints structure. The single-lap adhesive joint is the design dominating the range of adhesive joints. In this study, single-lap specimens with different joint dimensions were used for the tensile-shear test and finite element calculation in of order to investigate the effect of overlap length and adhesive-bonding thickness on adhesive strength and stress distribution of the joints. Consequently, it was found that overlap lap size and thickness can be important parameters of structure joints using adhesive bonding, which is effected on adhesive strength.