• Proceedings of the KWS Conference
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• 2003.11a
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• pp.200-203
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• 2003

The purpose of this paper is to investigate the influence of weld bead profiles on stress concentration factors (K$\sub$t/). We evaluated K$\sub$t/ by varying three parameters such as toe radii, flank angles and bead heights. The three parameters have similar effects on K$\sub$t/.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.204-206
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• 2003

The purpose of this study is to investigate the characteristics of X-grooved butt weldments of SM 490 A. The flank angles and toe radii of weld beads are measured and analysed statistically. In addition, other properties are also studied.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.113-114
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• 2007

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.332-335
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• 2007

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.340-342
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• 2005

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.177-184
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• 2014

In this study, we investigated the variations in welding residual stresses in dissimilar metal butt weld due to width of repair welding and re-distribution behaviors resulting from similar metal welding (SMW) and mechanical loading. To this end, detailed two-dimensional axi-symmetric finite element (FE) analyses were performed considering five different repair welding widths. Based on the FE results, we first evaluated the welding residual stress distributions in repair welding. We then investigated the re-distribution behaviors of the residual stresses due to SMW and mechanical loads. It is revealed that large tensile welding residual stresses take place in the inner surface and that its distribution is affected, provided repair welding width is larger than certain value. The welding residual stresses resulting from repair welding are remarkably reduced due to SMW and mechanical loading, regardless of the width of the repair welding.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.517-523
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• 2009

Magnesium alloys have many advantages such as a low density, high strength/weight ratio and well recycle. And joining process is absolutely necessary to expand the field of application of magnesium alloy. The main problems of conventional process such as arc welding for magnesium alloy are the inflammability, a tendency toward crack formation and the appearance of porosity during solidification. Laser welding technology is a promising means for overcoming these difficulties. This study is related to the laser weldability of AZ31 magnesium alloy, an all-purpose wrought alloy with good strength and ductility. The effect of welding conditions on the weldability of butt joints was examined. Also, the mechanical properties of butt welded joints were investigated by tensile test and hardness test.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.45-52
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• 2015

Even though a lot of efforts have been devoted to evaluate welding residual stress characteristics of nuclear components, from the view point of accuracy, there are still some arguments in application of engineering estimation schemes. In this paper, three-dimensional finite element analyses (FEA) were carried out to predict residual stress distributions in butt welds of a typical surge line piping. Mesh optimization was conducted and subsequent analysis results such as the axial and hoop stress components along the weld center line and inner wall. Moreover, alternative evaluation was conducted by using three representative equations and their results were compared to those of FEA. Thereby, key parameters affecting to temperature profiles and residual stress distributions were derived as well as an optimum engineering estimation scheme was recommended.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.35-43
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• 2007

Laser welding of metals has been widely used to improve a wear resistance and a corrosion resistance of the industrial parts. The objective of this research works is to investigate the influence of the process parameters, such as the welding for metals with CW Nd:YAG lasers. The bead-on-plate welding tests are carried out for several combinations of the experimental conditions. In order to quantitatively examine the characteristics of the butt welding, the welding quality of the cut section, stain-stress behavior and the hardness of the welded part are investigated. From the results of the investigation, it has been shown that the optimal welding condition without defects in the vicinity of the welded area and with a good welding quality is 1325W of the laser power, and 1.4m/min of laser welding speed.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.385-394
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• 2002

Currently, high strength steel is not used for steel bridges in Korea, except for the SM570 high strength steel in very isolated cases. The study aimed to promote the active adaptation of high strength steel for long-span steel bridges. Thus, the fatigue behavior of SM570 and POSTEN80 high strength steel was investigated. For the experimental study, the butt welded joints samples were manufactured. Likewise, regular amplitude tensile fatigue tests were conducted. Test results, e.g., location of fatigue cracks and their propagation were compared with the findings of other researchers. After analyzing the effects of fatigue strength, e.g., static tensile strength and plate thickness of base metal, basic data for fatigue design criteria of SM570 and POSTEN80 high strength steel were presented.