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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 21, Issue 7 - Dec 2003
Volume 21, Issue 6 - Oct 2003
Volume 21, Issue 5 - Sep 2003
Volume 21, Issue 4 - Aug 2003
Volume 21, Issue 3 - Jun 2003
Volume 21, Issue 2 - Apr 2003
Volume 21, Issue 1 - Feb 2003
Selecting the target year
Cracking in Welds and Its Prevention(VII) - Reheat Cracking in Welds -
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 5~7
Effect of Microstructure on Cold Cracking in Weld Metal
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 8~13
Trend in Digitalization of Welding Power Source and Application of Information Technology
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 14~20
Application of Waveform Control Technology in GMA Welding
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 21~26
Waveform Control and Welding Characteristics in Pulse Arc Welding Process
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 27~34
Snubber Design and Device Parallel Operation for High Frequency Welding Machine
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 35~41
A Study on the Development of Insulated Electrode Tip for Spot Welding to Reduce Indentation
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 42~47
Stainless rolling stocks are usually fabricated by spot welding process without painting. Indentation on the surface of the car body after spot welding injures the beauty of the stainless rolling stocks. In this study, insulated electrode tips to reduce the indentation are developed and applied to the actual spot welding works. The developed tips are composed of head, neck, hole for cooling water, body and resistance material. They provide large surface contact area with the base materials during spot welding and enhance the current density by necking. Experimental results using the developed tips show that small indentation and sufficient tensile shear strength is produced due to large contact area and enhanced current density.
Effect of Short Circuit Time Ratio and Current Control Pattern on Spatter Generation in
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 48~53
The object of this study is to examine the effect of short circuit time ratio (SCTR) and current rise delay time (Td) on the spatter generation at low and medium current range in
welding. The spatter was evaluated by the weight generated in the welding of bead-on-plate for 30 seconds (3 times). Td was varied by order of 0, 0.4, 0.8 and 1.2 msec. At each Td, the short circuit time ratio was varied by the output voltage of the welding power source. In the low current range, it was found that the optimum SCTR was 20~25%, and the minimum spatter generation weight was obtained in the case of Td=0.4msec and SCTR=22% even though the remarkable difference was not showed by the application of Td. In the medium current range, it was confirmed that the arc was stable though the SCTR was increased from 20% to 40% by the control of current wave. Spatter generation weight depended on the variation of Td, and the lowest value of spatter generation weight occurred at Td=0.8~1.2msec.
Estimation of Plate Deformation in Thermal Processing using the Eigenstrain Concept
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 54~59
In the present work, a formula for plate deformation produced by line heating, in terms of process parameters such as heat input and plate dimensions, is developed analytically using an eigenstrain concept. The residual deformation that was due to thermal process was depends on the magnitude and region of plastic strains at heating zone. The magnitude of plastic strains was determined by disk model and its region was calculated using the Rosenthal"s solution. The vertical displacement of the plate was analyzed by using an infinite laminated plate theory to consider a cuboidal inclusion with an eigenstrain. Comparison of the calculated results and experimental data shows the accuracy and validity of proposed method.thod.
A Study on Seam Tracking and Weld Defects Detecting for Automated Pipe Welding by Using Double Vision Sensors
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 60~65
At present. welding of most pipes with large diameter is carried out by the manual process. Automation of the welding process is necessary f3r the sake of consistent weld quality and improvement in productivity. In this study, two vision sensors, based on the optical triangulation, were used to obtain the information for seam tracking and detecting the weld defects. Through utilization of the vision sensors, noises were removed, images and 3D information obtained and positions of the feature points detected. The aforementioned process provided the seam and leg position data, calculated the magnitude of the gap, fillet area and leg length and judged the weld defects by ISO 5817. Noises in the images were removed by using the gradient values of the laser stripe's coordinates and various feature points were detected by using an algorithm based on the iterative polygon approximation method. Since the process time is very important, all the aforementioned processes should be conducted during welding.
A Study on Non-linear Behavior in Welded Structures by Mechanical Stress Release Method
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 66~71
The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure fur steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test and the proper degree of stress relaxation was measured by sectioning technique using strain gauge. Analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result.
Fatigue Crack Propagation Life of Partially Penetrated Butt Welds in High Strength Steel
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 72~79
Fatigue behaviour of partially penetrated butt-welded joints in high strength steel plates, in which crack-like structural defect, i.e. lack of penetration(LOP), is inevitably introduced during welding processes, was investigated. Fatigue lives of two types of welded joints, namely X-grooved and K-grooved joints, were experimentally determined first. Observed fatigue crack propagation behaviours of the partially penetrated butt-welds were interpreted through considering 3-dimensional semi-elliptical crack shape in front of the LOP. Based on such interpretation, a fracture mechanical method to estimate stress intensity factors at the crack tip was proposed. Since the fatigue lift of the partially penetrated butt-welds was strongly influenced by the ratio of size of the LOP to thickness, D/t, the D/t was used as a main parameter to calculate the fatigue lift by using the proposed method. Comparison of the fatigue lift obtained experimentally and analytically agreed well with each other. Hence it is suggested that the method used in this work to predict fatigue lift of the partially penetrated butt-welds can be applied to real cases with improved lift-prediction capability.
Predictive System Evaluation of Residual Stresses of Plate Butt Welding Using Neural Network
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 80~86
This study develops a system for effective prediction of residual stresses by the backpropagation algorithm using the neural network. To achieve this goal, a series of experiments were carried out to and measured the residual stresses using the sectional method. With the experimental results, the optional control algorithms using a neural network could be developed in order to reduce the effect of the external disturbances during GMA welding processes. Then the results obtained from this study were compared between the measured and calculated results, weld guality might be controlled by the neural network based on backpropagation algorithm.. This system can not only help to understand the interaction between the process parameters and residual stress, but also improve the quantity control for welded structures.
Strength Characteristics of Reduced Activation Ferritic Steel for Fusion Blanket by TIG Welding
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 87~92
JLF-1 steel (Fe-9Cr-2W-V-Ta), reduced activation ferritic steel, is one of the promising candidate materials for fusion reactor applications. Tensile properties of JLF-1 base metal and its TIG weldments has been investigated at the room temperature,
. The tensile strength of base metal (JLF-1) showed the level between those of weld metal and the Heat Affected Zone (HAZ). When the test temperature was increased from room temperature to high temperature (
), both strength and ductility decreased or base metal, weld metal and the HAZ. The longitudinal specimens of base metal represented similar strength and ductility at room temperature and high temperature, compared to those of transverse specimens. Little anisotropy for the rolling direction was observed in the base metal of JLF-1 steel.
A Fundamental Study on Forecast of the Thin Plate Welding Deformation by Numerical Simulation
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 93~98
For construction of steel structures, thin steel plates have been often used and welding is the main manufacturing process. However, welding processes cause some problems(welding residual stresses, welding deformations, etc.). In these problems, welding deformation is extremely harmful to the safety of structures especially. Therefore, in this study, a numerical analysis program based on large deformation plate theory has been developed to analyze and predict the welding deformation in thin plates. From the result of numerical analyse, we can find two parameters, thermal cycles and mechanical restraints affecting the welding deformation of structures. It is considered that large difference of thermal cycles and mechanical restraints in the width direction bring about welding deformation. Results of simulation have the same tendency of deformation distribution in width direction as experimental formulas.
A Study on Advanced Small Punch Test for Evaluation of Material Degradation in Weldment Microstructures
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 99~106
This research was aimed to evaluate the material degradation with various microstructures of X20CrMoV121 steel weldment by Advanced Small Punch(ASP) test. Due to the regional limitation on constitutive structures, the minimized loading ball(
) and bore diameter of lower die(
) were designed for the ASP test. The micro-hardness test was also performed to assess the mechanical properties with artificial aging heat treatment. Material degradation was estimated by ductile-brittle transition temperature(DBTT). The results obtained from the ASP test were compared with those from conventional small punch(CSP) test and CVN impact test for several weldment microstructures. It was found that the ASP test clearly showed the microstructural dependance on the material degradation in the weldment.
A Study for Joining of Silicon Nitride with Crystallized Glass Solder of
Journal of Welding and Joining, volume 21, issue 1, 2003, Pages 107~113
with crystallized glass solder was studied.
as a crystallizing reagent was used as a solder. To improve the hish temperature toughness of joined specimen, two stage heat treatment was applied to Joined sample for the crystallization of joined layer, Two factors, i.e. thickness of soldered layer and crystallization were taken and thier effects on joining strength were investigated by a SEM-EDX observation of joined interface and bending strength both at room and elevated temperatures. Obtained results are summarized as follows: (1) Nitrogen diffused from
to solder during the Joining process. Average amount of nitrogen in soldered layer depended on the thickness of the soldered layer and increased with decrease of the thickness. (2) Joining strength of the specimen having a thinner soldered layer was stronger than that of thicker layer. This can be mainly attributed to the difference of the nitrogen content in the soldered layer. (3) Higher content of nitrogen in solder brought forth higher viscosity of the solder. Hence the crystallization of the solder become more difficult in thinner layer of the solder than thicker one. (4) Thus, the effect of crystallization was evaluated mostly by the thicker layer specimen. Crystallization of soldered layer improved markedly the fracure strength of joining at higher temperatures than the softening temperature of glass solder.