• Journal of Korean Society of Steel Construction
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• v.29 no.3
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• pp.193-204
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• 2017

Fatigue strength of temporary steels and painted structural steels corroded under outdoor atmospheric environments is not clear. In this study, fatigue tests were carried out on steel plates which were cut off from 7-year-old temporary structural member under subway construction environment and from 75-year-old Yeongdo bridge member under marine atmospheric environment. After removing corrosion production on the steel surface, 3-dimensional surface geometry of the corroded steel was measured at intervals of $1.0{\times}1.0mm$, and corrosion characteristics such as minimum, maximum and mean values of residual thicknesses were calculated. From the fatigue test and FEM analysis results, the relationship between corrosion characteristics and fatigue behavior was presented, and change in fatigue strength of the unpainted and painted steels corroded in outdoor environments was also presented.

• Journal of Conservation Science
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• v.21
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• pp.41-48
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• 2007

The resistance for atmospheric corrosion of the conventional 5 epoxy resins (Araldite rapid, Araldite AW 106, Araldite SV 427, Devcon, and CDK), those were used to restoration of the iron relics, were investigated in this study. Temperature, UV light, and water were chosen for the factors of the atmospheric corrosion. The drastic voluminous changes of the epoxy resins were found at the temperature range between $40^{\circ}C$ and $70^{\circ}C$ After UV exposure, the colors of the epoxy resins were severely changed. In case of the indoor exposure the chroma value(${\Delta}E$) of the resins were less than 2, which showed a little changes of the colors. The result of the water contact angle test was Araldite rapid>AW 106>Devcon>SV 427>CDK. Although the contact angles of the resins were reduced by UV exposure, SV 427 was stable comparatively.

• Corrosion Science and Technology
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• v.17 no.6
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• pp.301-309
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• 2018

If galvanized steel is exposed to an outdoor environment, atmospheric corrosion will occur with time and red rust will form when the sacrificial protection capacity of zinc reaches its limit. With corrosion, the surface appearance of steel changes, and the properties of the exterior materials degrade. In this study, two kinds of galvanized steel, (GA and GI specimens) were subjected to an outdoor exposure test for 36 months in six regions of Korea. Chrominance (color, chroma, and brightness) and glossiness surface analyses were performed. The color change was not significant, regardless of the exposed area or the specimens tested. With increasing exposure times, the GA specimen became blackened by the formation of zinc oxide, and red coloration was increased by the formation of red rust. As the exposure time of GI specimen increased, the surface proceeded to blacken, but no red rust was formed and the color did not change significantly. Regardless of the outdoor exposure area or the specimen, longer exposure times led to lower glossiness, and this behavior appears to be influenced by the formation of zinc oxide.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.307-316
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• 1998

The effects of surface roughness on chromate conversion coating and the corrosion behavior of galvanized steel sheets were investigated. Surface roughness was differently given to the galvanized steel sheets tested and these were then chromated. Accelerated corrosion test was conducted under the condition of $30^{\circ}C$, 90%RH with flowing 200ppm $SO_2$ gas. The galvanized steels were also exposed to urban environment for 5 weeks. The corrosion rates were measured by weight gain method. The distribution of chromate film and corrosion product on the coating were examined which SEM/EDS. The chromate film formed preferentially at the convex sites rather than at the concave sites on the surface. The corrosion products were found at the concave sites where the chromate film formed rarely. The corrosion product on the coating were found at the concave sites where the chromate film formed rarely. The corrosion rates increased slightly with the surface roughness in accelerated corrosion test but significantly in field test.

• Corrosion Science and Technology
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• v.10 no.4
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• pp.109-117
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• 2011

The Korean Peninsula is located in the middle latitude of the northern hemisphere and has a clear 4-seasons and shows the typical temperate climate. Because of seasonal winds, it is cold and dry by a northwestern wind in the winter and it is hot and humid by a southeast wind in the summer. Also, temperature difference between the winter and the summer is large and it shows a rainy season from June to July but recently this regular trend may be greatly changed by an unusual weather phenomena. Since the Peninsula is east high west low type, the climate is complicated too. Because these geographical and climate characteristics can affect the properties of corrosion of metals and alloys, a systematic research on atmospheric corrosion in the Peninsula is required to understand and control the corrosion behavior of the industrial facilities. This paper analyzed the atmospheric corrosion factors for several environments in the Korean Peninsula and categorized the corrosivity of atmospheric corrosion of metals and alloys on the base of the related ISO standards. Annual pH values of rain showed the range of 4.5~5.5 in Korean Peninsula from 1999 to 2009 and coastal area showed relatively the low pH's rain. Annual $SO_2$ concentrations is reduced with time and its concentrations of every major cities were below the air quality standard, but $NO_2$concentration revealed a steady state and its concentration of Seoul has been over air quality standard. In 2007, $SO_2$classes of each sites were in $P_0{\sim}P_1$, and chloride classes were in $S_0{\sim}S_1$, and TOW classes were in ${\tau}_3{\sim}{\tau}_4$.That is, $SO_2$ and chloride classes were low but TOW class was high in Korean Peninsula. On the base of these environmental classes, corrosivity of carbon steel, zinc, copper, aluminium can be calculated that carbon steel was in C2-C3 classes and it was classified as low-medium, and zinc, copper, and aluminium showed C3 class and it was classified as medium.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.16-24
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• 2019

The corrosion amounts of steel structures can be different depending on their installation condition and height. Thus, their corrosion maintenance should be considered depending on installation conditions of local structural members. In this study, an atmospheric exposure test was conducted to evaluate the corrosion amount and the corrosion rate depending on the installation condition and height of a steel water gate using monitoring steel plates and corrosion environment measuring sensors. The mean corrosion depth was evaluated using the weight loss method and the galvanic corrosion current was measured by corrosion environment measuring sensors. Local corrosion rate of local structural member in steel water gate was estimated using measured mean corrosion depths and galvanic corrosion currents. From this measurement results, the corrosion damage in horizontal member of the cross beam was highly evaluated than those of other structural member as skin plate, etc. The relative difference in the corrosion rate of a local structural member could be highly affected by local corrosion environments of steel water gate members. Therefore, an appropriate maintenance method should be considered for local corrosion damages of local structural members determined by local corrosion environments of a steel water gate.

• Corrosion Science and Technology
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• v.11 no.4
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• pp.103-107
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• 2012

In the framework of an International cooperation program in Australia-Asia, the atmospheric corrosion of metals in five nations located in this tropical zone: Australia, Vietnam, Thailand, Philippines and Indonesia was investigated. In this program, mild steel, zinc and copper were tested on a set of sites, representative for different climatic conditions: severe marine, marine, industrial, urban and rural, simultaneously with the collection of climatic parameters and pollutants. Based on the data obtained in the Program and referring to the bank of data collected in the Vietnam National Projects, modeling was used to construct a corrosion map of steel for Vietnam. The correlation of the data derived from the map compared with those from National Projects is very high, in most cases, differing by less than 2-3%.

• Corrosion Science and Technology
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• v.8 no.4
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• pp.157-161
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• 2009

The corrosion resistance of reinforcing bar was studied to endure the marine environment during shipment. The red rust on the surface did not damage the adherence in the concrete structures, especially in highly alkaline environment, but made the consumer doubt of the quality. The passivation process by alkalization of the quenching water in the tempcore process failed to endure the long shipping period. The ceramic coating by sol-gel process improved the corrosion resistance without damaging the mechanical properties and adherence between concrete and reinfiorcing bar. Optimal concentration of the coating solution and coating temperature were tested. No additional energy was necessary for the coating process by spraying during cooling process, resulting simplified process and low cost. Salt spray test, cyclic corrosion test and atmospheric test were employed to confirm the resistance. The corrosion rates were presented by rating number and polarization resistance. The coating layer was examined by FIB, XRD and SEM etc.

• Corrosion Science and Technology
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• v.7 no.2
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• pp.99-111
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• 2008

Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.10
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• pp.883-887
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• 2016

This study aims to evaluate the corrosion behavior of a newly developed high-strength steel in marine environments. Metals used in seawater are easily deteriorated because of the presence of corrosive species such as chloride ions in it. Seawater causes much higher corrosion than fresh water. Thus, the corrosion of steel in marine environment has been recognized as a crucial problem in designing structures which cannot be cathodically protected. In this study, the corrosion resistance of a newly developed high-strength steel was evaluated. Four different specimens were tested to confirm the corrosion resistance. The exposure corrosion test was carried out by exposing the specimens to different marine environments such as atmospheric, tidal, splash, and submerged zones for two years. The specimens taken out from each location were cleaned ultrasonically and chemically prior to the evaluation of their corrosion resistance by the weight loss method. Finally, the pitting depth of the specimens was also measured to evaluate their pitting corrosion. The conditions used for the corrosion test were similar to the environmental conditions. The corrosion test results revealed that the corrosion rate and pitting corrosion of the newly developed high-strength steel was lower than that of the other carbon steels.