• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.421-429
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• 2018

In this study, various electrochemical experiments were carried out to compare the corrosion characteristics of AA5052-O, AA5083-H321 and AA6061-T6 in seawater. The electrochemical impedance and potentiostatic polarization measurements showed that the corrosion resistance is decreased in the order of AA5052-O, AA5083-H321 and AA6061-T6, with AA5052-O being the highest resistant. This is closely associated with the property of passive film formed on three tested Al alloys. Based on the slope of Mott-Schottky plots of an n-type semiconductor, the density of oxygen vacancies in the passive film formed on the alloys was determined. This revealed that the defect density is increased in the order of AA5052-O, AA5083-H321 and AA6061-T6. Considering these facts, it is implied that the addition of Mg, Si, and Cu to the Al alloys can degrade the passivity, which is characterized by a passive film structure containing more defect sites, contributing to the decrease in corrosion resistance in seawater.

• Journal of the Korean Society for Heat Treatment
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• v.13 no.1
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• pp.1-9
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• 2000

The microstructural characteristics and low temperature tensile properties between $25^{\circ}C$ and $-196^{\circ}C$ for as-welded and age hardened specimen by using Al 5083-H321 for base metal, 5083-5356 and 5083-4043 weldments have been investigated. The hardness of 5083-5356 weldment decreases with aging treatment, whereas the weld region of 5083-4043 weldment shows remarkable increase in hardness after aging due to the precipitation of fine Si particle at the grain boundaries and interiors. Low temperature tensile properties of 5083 AI base metal, 5083-5356 and 5083-4043 weldments appear to be the increment of tensile strengths and elongations at the room temperature and $-196^{\circ}C$, while the decrement of tensile properties around $-50^{\circ}C$ is shown. Through the observation of fine serration to fracture in the stress-strain curve and tensile fractography, the increment of localized deformation leading to promote the neck initiation and the increment of the dimple size cause to decrease in tensile strengths and elongations around $-50^{\circ}C$. For the tensile specimen of the 5083 base metal, 5083-5356 and 5083-4043 weldments, the reason to increase in elongation after solution and aging treatment is the diminishment of fine pit, the resolution of Mg into the matrix and the spheridization of the eutectic Si.

• Corrosion Science and Technology
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• v.19 no.4
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• pp.231-231
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• 2020

• Corrosion Science and Technology
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• v.19 no.5
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• pp.250-258
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• 2020

Recently, 5000 series and 6000 series Al alloys have been used as hull materials for small and medium-sized ships because of their excellent weldability, corrosion resistance, and durability in marine environments. Al ships can navigate at high speed due to their light weight. However, cavitation-erosion problems cause reducing durability of Al ship at high speed. In this investigation, 5052-O, 5083-H321, and 6061-T6 Al alloy materials were used to evaluate the damage characteristics with amplitude (cavitation strength). As a result of the electrochemical experiments, the corrosion current density and corrosion potential of 6061-T6 in seawater were 8.52 × 10-7 A/㎠ and -0.771 V, respectively, presenting the best corrosion resistance. The cavitation-erosion experiment showed that 5052-O had the lowest hardness value and cavitation-erosion resistance. 5052-O also had a very short incubation period. As the experiment progressed for 5052-O, pitting formed and grew in a short time, and was observed as severe cavitation-erosion damage that eliminated in large quantities. Among the three specimens, 5083-H321 presented the highest hardness value and the damage rate was the smallest after the initiation of pitting.

• Journal of the Korean institute of surface engineering
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• v.50 no.6
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• pp.498-503
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• 2017

The aim of the present study is to evaluate electrochemical corrosion characteristics of base metal and weldment of Al-Mg alloy in seawater solution. The specimen was 5mm thick 5083-H321 Al alloy plate which was butt-welded using gas metal arc welding (GMAW). To identify the types of inclusions in the weldment, the microstructural observation was performed along with Energy dispersive spectrometer (EDS) analysis. The anodic polarization experiments were performed to evaluate the corrosion characteristics. After the anodic polarization test, the corroded surface was observed by SEM(scanning electron microscope) and EDS. The result of the analysis revealed a large number of voids in the weldment, especially coarse grains and inclusions in the heat affected zone. The corrosion current density of the weldment was found to be approximately 13 times higher than that of the base metal, indicating lower corrosion resistance of the weldment due to the defects in the weldment and the heat affected zone.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.5
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• pp.481-487
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• 2012

Recently, the construction of the small Al alloy ships is an increasing trend in viewpoint such as the disposal issue of a retired ship, the enhancement of environmental regulation and resources recycling etc. for FRP ships. However, Al alloy ship which can achieve high speed by light weight in marine environment is exposed to a problem on materials damage by cavitation-erosion which is generated by large impact pressure with the collapse of air bubbles due to cavitation. Consequently, in this study, water cavitation peening technology was applied in Al alloy for ship to enhance durability life by preventing cavitation damage. So, the water cavitaton peening application time that presented the excellent cavitation characteristic investigated. The weight-loss of 5456-H116, 5083-H321 and 5052-O Al alloy at the optimum water cavitation peening time were improved to 42.11 %, 50.0 % and 25.7 %, respectively.

• Journal of the Korean Vacuum Society
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• v.2 no.3
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• pp.275-281
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• 1993

본 논문은 포항가속기에서 건설 중인 진공 chamger의 용접에 관한 것이다. 저장링에 전자빔을 5시간 이상 저장하기 위하여 10-10torr 이하로 진공도를 유지하도록 설계되어 있기 때문에 초고진공에 적합한 TIG 용접(tungsten inert gas welding)을 하였다. 진공 chamber는 Al 5083-H321이며 flange의 재질은 Al 2219-T852이다. Sector chamber I, II의 총 용접 길이는 각각 27m, 37m이며 진공에 유해한 균열과 virtual leak가 생기지 않도록 하는 용접조건 등을 선정하였다.

• Corrosion Science and Technology
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• v.22 no.5
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• pp.314-321
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• 2023

The aim of the present study was to investigate the effect of thymus extract on corrosion inhibition of aluminum 5083 alloy in a 0.1 M NaCl medium prepared using a mixture of ethylene glycol and water using potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic electrochemical technique showed an increase in corrosion inhibition efficiency starting from 49.63% at a concentration of 0.25 g/L to 92.71% at a maximum concentration of 1.25 g/L of the extract. These results were consistent with those obtained via EIS analysis. Spectral characterization of the tested plant extract using the Fourier-transform infrared spectroscopy (FTIR) technique confirmed the presence of organic compounds having different oxygen and aromatic functionalities in the extract that could help enhance the adsorption of these compounds on the aluminum surface. This study reveals possible adsorption isotherm of the thymus extract on the aluminum surface, supporting a Langmuir isotherm for the adsorption of inhibitor molecules on this surface.

• Journal of Welding and Joining
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• v.17 no.4
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• pp.32-38
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• 1999

PAL(Pohang Accelerator Laboratory) designed and manufactured a 5m-long straight vacuum chamber to adopt U7 undulator that is the first insertion device. Top and bottom plates of the vacuum chamber were made of Al alloy A5083-H321, and welded together by the GTAW welding. The leak rate is less than 1×{TEX}$10^{-10}${/TEX} torr·ℓ/s with negligible welding deformation. The pressure has been maintained below {TEX}$10^{-10}${/TEX} torr after installation. This paper reports the welding process and the method applied to achieve ultimate vacuum performance and t satisfy integrity of welds.

• Journal of the Korean Vacuum Society
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• v.1 no.1
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• pp.24-27
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• 1992

The Pohang Accelerator Lab is constructing a 2 GeV synchrotron radiation source. In order to achieve a beam lifetime of 5 hours or more, the average pressure in the vacuum chamber will be kept in the nano Torr range. Each chamber consists of a top and a bottom piece, which are machined separately and welded together. The chamber material is A1 5083-H321. The pumping system has nine sets of lumped NEGs in tandem with ion pumps installed beneath photon stops, and six ion pumps per superperiod. A prototype chamber will be machined by February 1992. After various tests with the prototype chamber, the vacuum chamber design will be refined.