• Journal of Welding and Joining
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• v.20 no.6
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• pp.796-801
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• 2002

Corrosion and tensile properties of zircaloy-4 cladding tube having a laser welding part in elevated temperature are studied to present the criterion of quality evaluation in nuclear reactor and find the scientific basis of SCC, with laser welding method using by coupling up cladding tube to end cap. In the result of tensile test($400^{\circ}C$), the fracture is not happened in the welding part but base metal and the result of corrosion test($400^{\circ}C$ 1500psi steam), corrosion rate of the molten zone and PMZ is a little higher than the other zone.

• Journal of Welding and Joining
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• v.32 no.1
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• pp.34-39
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• 2014

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.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.567-573
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• 2016

GMAW and GTAW processes have been used for welding of equipment mounting pads during decades. For improving the mobility and survivability of KWV(Korean Wheeled Vehicle), various types of equipment are required and numbers of pads for welding were increased. In this research, for improving productivity of mounting pads welding process, new technology of stud welding was studied. In this study, mechanical properties of stud weldment were investigated to compare with those of GMAW weldment. Also, research of stud weldment durability was carried out and proved its fatigue strength under the condition of KWV's 32,000 km load profile.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.525-531
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• 2014

A cowl cross is a part of the car's instrument panel used to maintain the rigidity of the vehicle body side. The application of laser welding has the benefits of speed and thermal deformation compared to arc welding. An ultra-high strength steel sheet is used to reduce the weight of the vehicle body parts. Generally, formability of such a steel sheet is poor because its elongation is very low. For this reason, a method for cold forming of an ultra-high strength steel sheet is required. This paper describes how to improve the formability and weldability of the ultra-high strength steel sheet. Mechanical tests of this material were also performed to evaluate the welding properties of $CO_2$ (GMAW) and those of laser welding.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.88-93
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• 1999

This paper presents the experimental examinations and statistical quantitative analysis of the correlation between the cumulative counts of acoustic emission(AE) during plastic deformation periods of the welding and the tensile strength and other properties of the bar-to-bar welded joints of O.D. 16mm shaft(SM40C) as well as the various welding variables. And this is a new approach which attempts finally to develop real-time quality monitoring system for friction welding. The results lead to a practical possibility of real-time quality control more than 100% joint efficiency showing good weld with no micro structural defects.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.1001-1008
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• 2012

Non-destructive testing (NDT) is a technique used in science and industry to evaluate the properties of a material without causing damage. In this paper we propose a method for segmenting radiographic images of welding in order to extract the welding defects which may occur during the welding process. We study different methods of level set and choose the model adapted to our application. The methods presented here take the property of local segmentation geodesic active contours and have the ability to change the topology automatically. The computation time is considerably reduced after taking into account a new level set function which eliminates the re-initialization procedure. Satisfactory results are obtained after applying this algorithm both on synthetic and real images.

• Journal of Welding and Joining
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• v.17 no.2
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• pp.84-90
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• 1999

The shape of weld nuggest in arc spot welding of 304 stainless steel was found by searching thermal history of a weld joint through a three-dimensional finite element model. The problem consists of one in which the finite element mesh is growing continuously in time in order to accomodate metal transfer in arc spot welding using element rebirth technique. The analysis was performed on the basis of experimental results. The finite element program MARC, along with a few user subroutines, was employed to obtain the numerical results. Temperature-dependent thermal properties, stir effect in weld pool, effect of phase transformation, and the convective and radiative boundary conditions are included in the model. Numerically predicted shape of weld nuggest is compared with the experimentally observed shape.

• Journal of Welding and Joining
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• v.22 no.1
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• pp.43-49
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• 2004

Contact tip is located so near to welding arc that it is heated to high temperature during long time welding. In such a situation, tip changes in its microstructure and in turn its mechanical properties. This study was intended to investigate those changes by using simulated heat treatment. As a result of this study, it was confirmed that tip of Cu-P alloy hardened with severe cold deformation lose its initial hardness to a large extent within 60 min due to the occurrence of rapid recrystallization while that of Cu-Cr composition hardened by proper aging treatment can preserve its intial hardness for about 1,000 min or longer. Based on these results, suggested was a guideline that can classify contact tips into two different grades: deformation-hardened type and precipitation-hardened type. Following a guideline, a tip with Cu-Cr composition can be classified into the deformation-hardened type if it is in the over-aged condition. Such a guideline is well described.

• Journal of Welding and Joining
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• v.26 no.1
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• pp.69-75
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• 2008

Spot welding which use the main process for side block production of stainless steel railway vehicle is legged behind in laser welding about a quality and productivity. Although the laser welding has many potential advantages such as low heat input and aspect ratio of weld bead, its application to a new structural component still is required many engineering data including mechanical properties such as tensile, fatigue strength, etc on. Therefore, experimental analysis was carried out to understand the fatigue phenomena of different thickness stainless steel overlap joining panels by Nd:YAG laser welding. The fatigue life curves were obtained through fatigue tests with the various levels of applied load. The fatigue life is related with the parameters such as gap size and penetration depth through experiment. As the results, tensile strength and fatigue life were proportional in heat input level and gap was identified the major factor for fatigue life. Also we could know that deferent a-ferrite content at HAZ depend on welding heat input was important factor to determine a formation of initial crack and total fatigue life cycle.

• Journal of Welding and Joining
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• v.32 no.6
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• pp.64-69
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• 2014

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.