• Proceedings of the KWS Conference
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• 2007.11a
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• pp.288-290
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• 2007

Ir-192 source is one of the most widely used radioisotopes in the field of non-destructive testing applications. To obtain radiation safety it is necessary to take into consideration integrity of welded joint in the production of sealed radiation source. Generally, the quality of a resistance welded joint is strongly influenced by process parameters during the welding process such as current, welding time and applied force. In this study, resistance welding technology and system were developed for sealing of Ir-192 industrial radiation source capsules. In order to evaluate the weld quality in real time, quantitative relationships between process parameters and electrode displacement were also established.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.7 s.250
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• pp.865-872
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• 2006

High frequency induction welding is widely employed for longitudinal seam welding of small scale tubes and pipes because of its relatively high processing speed and efficiency. This research is aimed at understanding the variables that affect the quality of the high frequency induction welding. The welding variables include the welding frequency, weld speed, V-angle and tube thickness. Temperature distribution of the tube is calculated through three dimensional coupled electromagnetic and thermal FE analysis. The skin and proximity effects are considered in the electromagnetic analysis. The influence of the impeder is also analyzed. The effects of the operating welding variables on the temperature distribution are investigated quantitatively by exhibiting the heat affected zone (HAZ). The results explain the mechanism of significant enhancement of welding efficiency when the impeder is used. The proper welding conditions without the overheated edge are obtained through FE analysis.

• 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 Welding and Joining
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• v.34 no.4
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• pp.62-66
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• 2016

The trend of the fabrication technology of high strength, high toughness aluminum alloys by the severe plastic deformation(SPD) process and the welding technology of lightweight alloys in the automobile has been studied. The lightweight aluminum alloys can reduce vehicle weight, while stringently demanding the high quality and efficient welding techniques, to produce the best weldments. Among the production technologies, welding plays an important role in the fabrication of lightweight vehicle structure. This paper covers the scientometric analysis of the severe plastic deformations of lightweight alloys and the welding technology in the automobile which are based on the published research works in the 'HPT, ECAP and rolling', and 'welding technology of the automobile' obtained from Web of Science, and deals with the details of the background data of the HPT, ECAP, and rolling of lightweight alloys, and welding technology of the automobile technology.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.3
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• pp.124-130
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• 2019

Friction stir welding is one of the interesting welding methods for titanium and its alloy which proceeds with plastic flow due to thermo-mechanical stirring and friction heat. Solid-state welding can solve severe problems such as high-temperature oxidation, interstitial oxygen diffusion and grain coarsening by liquid-state welding. Dynamic recrystallization and grain refinement can vary significantly with the plunging load and rotational speed of tool during friction stir welding, and suitable process conditions must be optimized to obtain microstructure and better mechanical characteristics. Suitable FSW conditions were 1000 kg of plunging load and 200 rpm of rotational speed and it showed YS 270 MPa, UTS 332.1 MPa, and El 17.3%, which were very similar to those of wrought titanium sheet.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.153-160
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• 2019

Welding often results in welding distortion during the assembly process. The welding distortion of thin-plate structures such as the living quarters of ships and offshore installations is a more significant problem than in the case of thick-plate structures. Pre-stressing/heating and fairing, which are additional works to mitigate and control welding distortion, are inevitable, and the construction planning is accordingly delayed. In order to prevent welding distortion and minimize the additional work during the assembly process, increasing the plate thickness and/or the number of stiffeners may be a simple solution, but it may give rise to problems related to cost and weight. In this study, the welding distortion control effect of the type of stiffeners on the door openings of various living quarter structures was investigated using an experimental method and a finite element method. The results showed the feasibility of mitigating and controlling the welding distortion, and the optimum selection of the type of stiffeners was confirmed.

• Corrosion Science and Technology
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• v.5 no.6
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• pp.196-200
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• 2006

For the evaluation of corrosion resistance of Al 6061-T6 alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.2
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• pp.147-158
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• 2016

Objectives: The objective of this study was to evaluate the assessment of exposure to welding fume and heavy metals among construction welders. Methods: Activity-specific personal air samplings(n=206) were carried out at construction sites of three apartment, two office buildings, and two plant buildings using PVC(poly vinyl chloride) filters with personal air samplers. The concentration of fumes and heavy metals were evaluated for five different types of construction welding jobs: general building pipefitter, chemical plant pipefitter, boiler maker, ironworker, metal finishing welder. Results: The concentration of welding fumes was highest among general building pipefitters($4.753mg/m^3$) followed by ironworkers($3.765mg/m^3$), boilermakers($1.384mg/m^3$), metal finishing welders($0.783mg/m^3$), chemical pipefitters($0.710mg/m^3$). Among the different types of welding methods, the concentration of welding fumes was highest with the $CO_2$ welding method($2.08mg/m^3$) followed by SMAW(shield metal arc welding, $1.54mg/m^3$) and TIG(tungsten inert gas, $0.70mg/m^3$). Among the different types of workplace, the concentration of welding fumes was highest in underground workplaces($1.97mg/m^3$) followed by outdoor($0.93mg/m^3$) and indoor(wall opening as $0.87mg/m^3$). Specifically comparing the workplaces of general building welders, the concentration of welding fumes was highest in underground workplaces($7.75mg/m^3$) followed by indoor(wall opening as $2.15mg/m^3$). Conclusions: It was found that construction welders experience a risk of expose to welding hazards at a level exceeding the exposure limits. In particular, for high-risk welding jobs such as general building pipefitters and ironworkers, underground welding work and $CO_2$ welding operations require special occupational health management regarding the use of air supply and exhaust equipment and special safety and health education and fume mask are necessary. In addition, there is a need to establish construction work monitoring systems, health planning and management practices.

• Journal of Welding and Joining
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• v.30 no.2
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• pp.43-46
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• 2012

• Journal of Welding and Joining
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• v.30 no.2
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• pp.31-36
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• 2012