• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.278-284
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• 2021

Corrosion of steel plate is common phenomenon which results in the gradual destruction caused by a wide variety of environments. Corrosion monitoring is the tracking of the degradation progress for a long period of time. Corrosion on steel plate appears as a discoloration and any irregularities on the surface. In this study, we developed a quantitative evaluation method of the rust formed on steel plate by using k-means clustering from the corroded area in a given image. The k-means clustering for automated corrosion detection was based on the GrabCut segmentation and Gaussian mixture model(GMM). Image color of the corroded surface at cut-edge area was analyzed quantitatively based on HSV(Hue, Saturation, Value) color space.

• Journal of the Korea Concrete Institute
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• v.12 no.3
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• pp.21-30
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• 2000

Recently, reinforced concrete structures exposed to severe enviroment are increased in metropolitan area. The acid rain and CO2 penetrated towad rebar, thus rebar corrosion occurred. The corrosion of rebar in concrete is, as in most corrosion processes, an electrochemical nature. The corrosion may severely affect on durability and service life of such a concrete structures. This study was performed for the purpose of acquiring data about corrosion condition and considering a countermeasure to prevent rebar from corroding due to carbonation of concrete. An accelerated car bonation testing procedure was applied to measure the evolution of carbonation and rebar corrosion with time for various water-binder ratios and cement types.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.2
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• pp.216-227
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• 1992

The corrosion rate, behavior of corrosion fatigue and characteristic of cathodic protection for SB41 were investigated by corrosion and corrosion control tests in seawater at laboratory and coast. The main result obtained are as the following; 1) The corrosion rate of base metal (BM) is about 28-37 mg/dm super(2) day in seawater of coast. 2) The correlation between the stress intensity factor range $\Delta$K and crack propagation rate da/dN for weldment follows paris' rule in seawater : da/dN=C($\Delta$K) super(m) where m is the slope of the correlation, and is 2.02 for BM and 1.75 for heat affected zone (HAZ) respectively. 3) The corrosion sensitivity of HAZ is more sensitive than that of BM under the low region of $\Delta$K. 4) With increase of bared surace area of cathode, cathodic protection potential is increased sharply.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.57-69
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• 1997

The objetive of this study is to compare the mechanical proprties of 6000 series Al-Mg-Si aluminum alloy (AC120) with 5000 series Al-Mg aluminum alloy (TG25), and to investigate the influence of corrosion solution for fatigue life. Comparing of TG25 and AC120 alloy sheets, TG25 alloy sheets showing higher plastic ratio and total elongation have better formability than AC120 alloy sheets. The hardness of nugget area was a little higher than that of base metal area. Also, grain coarsening was observed in HAZ(Heat Affected Zone). In a corrosion fatigue experiment, the fatigue life decreased as concentration increased, when a dipping time was constant. The life decreased as dippling time increased, when a concentration was constant.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1709-1711
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• 2001

The remaining life of ACSR(Aluminum Conductor Steel Reinforced) wires exposed to the atmosphere for a long period relies on the extent of deterioration caused by environmental factors such as atmospheric corrosion, galvanic corrosion, crevice corrosion and fatigue corrosion. We investigated the tensile characteristics of ACSR wires in a coastal area through several mechanical tests, and analyzed the constituents of them using SEM(scanning electron microscope). Test samples are parts of ACSR 97[$mm^2$] overhead transmission lines in that area. The result shows that ACSR wires exposed to salt may lead to rapid mechanical deterioration.

• Corrosion Science and Technology
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• v.20 no.5
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• pp.242-248
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• 2021

Unforeseen failures of boilers in power plants may affect the continuation of electricity generation. Main failures in boilers are influenced by the tube material, tube position, boiler service temperature and pressure, and chemical composition of the feed water and coal. This investigation was intended to find answers on the causes and mechanism of failure of the fire-side boiler water-wall tubes, due to perforation and corrosion. The tube conformed to the material requirements in terms of its chemical composition and hardness. Microscopic examination showed ferrite and pearlite indicating no changes in its microstructure due to the temperature variation. SEM test showed a single layer and homogenous film density particularly on the area far from perforation. However, layers of corrosion product were formed on the nearby perforation area. EDX showed that there were Na, Ca, S, and O elements on the failed surface. XRD indicated the presence of Fe₂O₃ oxide. The failure mechanism was identified as a result of significant localized wall thinning of the boiler water wall-tube due to oxidation.

• Geomechanics and Engineering
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• v.17 no.2
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• pp.157-164
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• 2019

The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1069-1072
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• 2008

As embedded reinforcing suffer from corrosion process, the bond strength and stiffness are reduced, and the structure proceed, eventually, to the deterioration of the concrete, shortening the service life of concrete structures rapidly. In order to deal with these problems, a multitude of researches have been carried out up to this date to evaluate the bond characteristics of RC members, i.e. by artificially inducing rapid corrosion of the reinforcing bar. These artificial corrosion methods, however, could not represent the real condition, resulting in the possibility of overestimation for the RC members in real situation. Accordingly, the purpose of this paper is to investigate the difference in the bond characteristics for RC members corroded by different corrosion methods (artificial rapid method, natural method). For the case of natural corrosion, the brittle failure was observedeven for the case of the area ofcorrosion of 50%. And, the bond strength decreased by about 10% or more for the caseofspecimens with the area of corrosion of 80% or above. Especially, the deterioration of concrete starts at the state of low corrosion level for the case of natural corrosion. Thus, the safety of RC members must be assessed and evaluated more carefully for the naturally corroded members than for the RC concrete members corroded rapidly by artificial method.

• Corrosion Science and Technology
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• v.3 no.2
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• pp.47-53
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• 2004

The conditions to simulate the atmospheric corrosion behavior in the laboratory were investigated to clarify atmospheric corrosion mechanism of steel material in coastal area, For airborne sea salt and artificial seawater droplet, the various behaviors were observed by optical microscope, The particle size of the dried airborne sea salt was about $20{\mu}m$, and was about 1/10 compared with the artificial seawater droplet. Though the airborne sea salt represented the same behavior as the thermodynamic water absorption, the behavior of the artificial seawater droplet deviated from the results of the thermodynamic calculation, It is concluded that the water absorption behavior is influenced by the particle size of the dried sea salt. The corrosion behaviors of carbon steels were observed under the deposited condition of airborne sea salt and artificial seawater droplet. The corrosion behaviors showed a different trend, indicating that the corrosion behavior depended on the particle size of the dried sea salt. The corrosion in the actual environrnent progressed greater than that in the chamber. Furthermore, the summer showed the greater corrosion than the spring. It is found that the corrosion behaviors are attributed to the influence of the environmental factors.

• Journal of Ocean Engineering and Technology
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• v.11 no.2
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• pp.28-38
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• 1997

The corrosion fatigue test was conducted in air to investigate the corrosion fatigue strength of SM 30 C steel by which was corroded in the under sea and surface in the conditions of 3.0% NaCl salt solution. The fatigue tests were carried out on a rotary bending testing machine of cantilever type. The corrosion effect of the sea surface conditionwas served more than that of the under sea condition which was due ti the periodic contact of air thus accelerate the corrosion. The difference of the fatgue strength between sea surface and under sea conditions decreased with increase of stree level and corroded period. Inthe case of the solid shaft and thickness 2mm of hollow shaft, the difference of corrosion fatigue strength decreased as stress level and corrosion periodic increasing. Onthe contrary in the case of thickness 1mm of hollow sgaft, the difference of it increased as stress level, corrosionn periooodic increasing and also the condition of corrosion chaanged. The main factors affecting the degradation of fatigue strength due to corrosion were the reduction of sectional area and the increase of surface roughness. The interference phenomenon increase with stress level got higher.