• Journal of Korea Foundry Society
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• v.40 no.5
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• pp.129-133
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• 2020

The outcomes of solution annealing and stress corrosion cracking in cold-worked 316L austenitic stainless steel have been studied using x-ray diffraction (XRD) and the slow strain rate test (SSRT) technique. The good compatibility with a high-temperature water environment allows 316L austenitic stainless steel to be widely adopted as an internal structural material in light water reactors. However, stress corrosion cracking (SCC) has recently been highlighted in the stainless steels used in commercial pressurized water reactor (PWR) plants. In this paper, SCC and inter granular cracking (IGC) are discussed on the basis of solution annealing in a chloride environment. It was found that the martensitic contents of cold-worked 316L stainless steel decreased as the solution annealing time was increased at a high temperature. Moreover, mode of SCC was closely related to use of a chloride environment. The results here provide evidence of the vital role of a chloride environment during the SCC of cold-worked 316L.

• Journal of Power System Engineering
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• v.19 no.5
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• pp.38-44
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• 2015

The cold-rolled steel sheet for automobile is liable to corrosion, and will be painting in a variety of ways for the anticorrosive. This paper was coated on cold rolled steel (SPCC and SPFC590) for automobiles using five kinds of organic/inorganic hybrid solution. This was evaluated corrosion resistance and so on by the salt spray. Corrosion area was less according to increasing of curing time in 2 types of steel plate with 5 types of the coating solution. No.1 solution was showed the best corrosion resistance regardless of the kinds of the steel sheet. It is judged that the melamin hardner had the role of bridge between $SiO_2$ polysilicate and urethan resin. Other properties were excellent in all solution.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.247-260
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• 2010

The developement of a HLW disposal canister is under way in KAERI using Cold Spray Coating technique. To estimate corrosion behavior of a cold sprayed copper, a creivice corrosion test was conducted at Southwest Research Institute(SWRI) in the United State. For the measurement of repassivation potential needed for crevice corrosion, three methods such as (1) ASTM G61-86 : Cyclic Potentiodynamic Polarization Measurements, (2) Potentiodynamic Polarization plus intermediate Potentiostatic Hold method, and (3) ASTM G192-08 (THE method) : Potentiodynamic- Galvanostatic-Potentiostatic Method, were introduced in this report. In the crevice corrosion test, the occurrence of corrosion at crevice area was optically determined and the repassivation potentials were checked for three kind of copper specimens in a simulated KURT underground water, using a crevice former dictated in ASTM G61-86. The applied electrochemical test techniques were cyclic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy. As a result of crevice corrosion tests, every copper specimens including cold sprayed one did not show any corrosion figure on crevice areas. And the open-cell voltage, at which corrosion reaction initiates, was influenced by the purity of copper, but not their manufacturing method in this experiment. Therefore, it was convinced that there is no crevice corrosion for the cold sprayed copper in KURT underground environment.

• Journal of the Korean Society of Safety
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• v.12 no.1
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• pp.19-28
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• 1997

This study was made of the effect of cold working on the stress corrosion cracking(SCC) of austenitlc 304 stainless steel in boiling 42% $MgCl_2$ solution. For this experiment, specimens cold-worked of 0%, 10%, 20%, 30%, 40% were fabricated respectively, and then experiments of mechanical properties and stress corrosion cracking(SCC) of these specimens were carried out. The results of these experiments indicate that the maximum resistance to SCC showed at 20% of cold working degree and that the SCC susceptibility depended on the volume fraction of deformation-induced martensite by cold working and the work hardening of matrix. On the other hand, the fracture mode was changed. This phenomenon was considered that deformation-induced martensite was grown from transgranular fracture mode to intergranular fracture mode and caused by increased of dislocation density along the slip planes.

• Steel and Composite Structures
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• v.48 no.1
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• pp.27-41
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• 2023

Under the long-term effect of corrosive environment, many cold-formed steel (CFS) structures have serious corrosion problems. Corrosion leads to the change of surface morphology and the loss of section thickness, which results in the change of instability mode and failure mechanism of CFS structure. This paper mainly investigates the elastic local buckling behavior of corroded CFS columns. The surface morphology scanning test was carried out for eight CFS columns accelerated corrosion by the outdoor periodic spray test. The thin shell finite element (FE) eigen-buckling analysis was also carried out to reveal the influence of corrosion surface characteristics, corrosion depth, corrosion location and corrosion area on the elastic local buckling behaviour of the plates with four simply supported edges. The accuracy of the proposed formulas for calculating the elastic local buckling stress of the corroded plates and columns was assessed through extensive parameter studies. The results indicated that for the plates considering corrosion surface characteristics, the maximum deformation area of local buckling was located at the plates with the minimum average section area. For the plates with localized corrosion, the main buckling shape of the plates changed from one half-wave to two half-wave with the increase in corrosion area length. The elastic local buckling stress decreased gradually with the increase in corrosion area width and length. In addition, the elastic local buckling stress decreased slowly when corrosion area thickness was relatively large, and then tends to accelerate with the reduction in corrosion area thickness. The distance from the corrosion area to the transverse and longitudinal centerline of the plate had little effect on the elastic local buckling stress. Finally, the calculation formula of the elastic local buckling stress of the corroded plates and CFS columns was proposed.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.1
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• pp.55-66
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• 2024

In this study, we investigated the suppression of the corrosion of cast iron in a copper-cast iron double-layered canister under local corrosion of the copper layer. The cold spray coating technique was used to insert metals with lower galvanic activity than that of copper, such as silver, nickel, and titanium, between the copper and cast iron layers. Electrochemically accelerated corrosion tests were performed on the galvanic specimens in KURT groundwater at a voltage of 1.0 V for a week. The results revealed that copper corrosion was evident in all galvanic specimens of Cu-Ag, Cu-Ni, and Cu-Ti. By contrast, the copper was barely corroded in the Cu-Fe specimens. Therefore, it was concluded that if an inactive galvanic metal is applied to the areas where local corrosion is concerned, such as welding parts, the disposal canister can overcome local or non-uniform corrosion of the copper canister for long periods.

• Steel and Composite Structures
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• v.37 no.3
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• pp.353-369
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• 2020

Eight cold-formed thin-walled steel beams were performed to investigate the effect of corrosion damage on the flexural behavior of steel beams. The relationships between failure modes or load-displacement curves and corrosion degree of steel beams were investigated. A series of parametric analysis with more than forty finite element models were also performed with different corrosion degrees, types and locations. The results showed that the reduction of cross-section thickness as well as corrosion pits on the surface would lead to a decline in the stiffness and flexural capacity of steel beams, and gradually intensified with the corrosion degree. The yield load, ultimate load and critical buckling load of the corroded specimen IV-B46-4 decreased by 22.2%, 26% and 45%, respectively. The failure modes of steel beams changed from strength failure to stability failure or brittle fracture with the corrosion degree increasing. In addition, thickness damage and corrosion pits at different locations caused the degradation of flexural capacity, the worst of which was the thickness damage of compression zone. Finally, the method for calculating flexural capacity of corroded cold-formed thin-walled steel beams was also proposed based on experimental investigation and numerical analysis results.

• Corrosion Science and Technology
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• v.7 no.2
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• pp.134-137
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• 2008

Cold arc welding of cast iron has been widely used with repair welding of metal structures. However its welding is often resulted in the galvanic corrosion between weld metal zone and heat affected zone(HAZ) due to increasing of hardness. In this study, corrosion properties such as hardness, corrosion potential, surface microstructures, and variation of corrosion current density of welding zone with parameters of used electrodes for cast iron welding were investigated with an electrochemical evaluation. Hardness of HAZ showed the highest value compared to other welding zone regardless of kinds of used electrodes for cast iron welding. And its corrosion potential was also shifted to more negative direction than other welding zone. In addition, corrosion current density of WM in polarization curves was qualitatively smaller than that of HAZ. Therefore galvanic corrosion may be apparently observed at HAZ. However galvanic corrosion may be somewhat controlled by using an optimum welding electrode.

• Corrosion Science and Technology
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• v.23 no.4
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• pp.289-295
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• 2024

Zn-Mg-Al alloy hot-dip galvanized steel sheet has high corrosion resistance. Compared to conventional Zn coating with the same coating thickness, the high corrosion resistance Zn-Mg-Al coating is more corrosion-resistant. Various coating compositions are commercially produced and applied in diverse fields. However, these steel sheets typically contain up to 3 wt% magnesium. In recent years, there has been a growing demand for higher corrosion resistance in harsh corrosive environments. Therefore, variations in Mg and Al contents were investigated while evaluating primary properties and performance. As a result, we developed new alloy-coated steel with ultra-high corrosion resistance. A Zn-5 wt%Mg-Al coated steel sheet was evaluated for its corrosion resistance and various properties. As the amount of Mg added increased, the corrosion loss tended to decrease. The corrosion resistance of the coated steel sheet in a particular composition, the Zn-5 wt%Mg-Al coating sheet, was about 1.5 to 2 times higher than that of the conventional Zn-3 wt%Mg-Al coating sheet. Ultimately, this ultra-high corrosion-resistance coated steel sheet will provide a robust solution to conserve Zn resources and contribute to a low-carbon society.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.20-28
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• 2016

This study has developed an organic/inorganic hybrid solution by addition of $SiO_2$ polysilicate and Melamine to the urethane. The three types of cold rolled steel were evaluated a corrosion resistance properties by using these solutions. The urethane solution(U) and the urethane solution with $SiO_2$ polysilicate($US_7$) were generate a lot of corrosion. The urethane solution with $SiO_2$ polysilicate and melamine($US_7M_3$) was excellent in corrosion resistance, regardless of the steel type. In addition, corrosion resistance has been shown to depend on the tensile strength. The appearance of coating by U and $US_7$ solution is bumpy surface, and were a lot of fine defects. $US_7M_3$ solution is made a sophisticated molecular cross-linking structure inside the coating, it was a slick surface. Other characteristics are exhibited the excellent property for all solutions.