Appropriate Environmental Sphere of Application for Unpainted Weathering Steel

Kim, Sang-Sik 한국공업화학회 2003 Journal of Industrial and Engineering Chemistry Vol.9 No.2

The current study was carried out to establish the appropriate environmental sphere of application for unpainted weathering steel as civil structures. such as bridge sructures, general construction, electric posts, guide rails, etc. As such, based on existing guideline for acceptable flying marine salt concentrations, the suitability of 4 selected locations was investigated in relation to environmental factors, including the direction and velocity of the wind, rainfall, humidity. and temperature. The results for the flying marine salt concentrations, considering the character of the selected Iocations, were as follows: the maximum and minimum flying marine salt concentrations measured by the gauge method at the selected locations #1, #2, #3, and #4 were 0.046 and 0.094, 0.08 and 0.131, 0.050 and 0.08, and 0.021 and 0.051 mg-Nacl/dm²/day, respectively. The concentrations of flying marine salt at locations #3 and #4 were lower than 0.1 mg-NaCI/dm²/day, indicating that the application of unpainted weathering steel was possible in these positions. However, the maximum concentration of flying marine salt at location #2 was 0.131 mg-NaCI/dm²/day. Accordingly, the current results revealed that locations #3, and #4, which were farther than 1000 m from the sea coast, were appropriate envirouments for the use of unpainted weathering steel, whereas location #2, which was less than 1000 m from the sea coast was found to be an unsafe environment for the use of unpainted weathering steel.

철을 이용한 실내외 환경조형물 제작에 관한 연구

변건호(Byun Kun Ho) 한국조형디자인학회 2005 조형디자인연구 Vol.8 No.2

The development of industry from ancient times to the present has been underlaid with abilities to handle iron. Assuming that the value and utility of iron as a material of formative arts and crafts have not been appreciated properly, the present study purposed to suggest methods of utilizing iron as a formative material of contemporary arts and crafts. For this purpose, we reviewed the basic properties of iron and examined different kinds of iron and iron alloys. In addition, we investigated the strong points and excellencies of iron, looked for methods of creating environmental formations using iron and evaluated the aesthetic value of !fon. Iron is a widely used important material because it has high strength, hardness and tenacity compared to other metals and the properties can be enhanced to some degree through heat treatment. However, because pure iron is too tender and impractical, it is alloyed with other elements. Among alloys, stainless steel has beautiful surface and high resistance against corrosion, so it is usable without surface treatment such as coating and painting and, as a result, it does not cause environmental contamination. Thus the material is considered to have many positive aspects for the environment. Steel material is economically efficient due to the large amount of deposits. Raw material can be mass-produced and it can be formed and processed into final products. Furthermore, its workability such as cutting and welding is higher than other structural materials, so the material is suitable for part processing and assembly industries. However, because iron is easily corroded and oxidized in the air, it needs to have separate chemical treatment such as surface treatment and coating. For this, external materials with improved surface treatment and corrosion-resistance are being developed recently and one of them is weathering steel. Weathering steel is less corrosive in the air and highly corrosion- resistant compared to ordinary steel. In addition, a stable film is formed over time, which prevents the progress of corrosion and reduces the cost of structure maintenance. Because of these advantages, weathering steel is spotlighted as a new material distinguished from existing finishing materials and expanding its application as an external material of construction. In addition, it is an environment- friendly external material in that it can be used as it is without additional artificial surface treatment. One of patterns that can be called 'contemporary' in fine art since the 20th century is the emergence of iron formations based on welding technology, and another is the establishment of the concept of environmental formations. Formations have a direct relation with vanous materials that have their own uruque properties. With the materials, artists express their ideas in natural forms, and one of their important jobs is to discover beauty latent in the materials. The plasticity, permanence and economic efficiency of Iron suggest new possibility of creation in terms of material and technique. In addition, the durability, heavy feel and gigantic scale of iron make it a suitable material of environmental formations in harmony with urban spaces of contemporary society. Environmental formations are structures installed inside and outside buildings to improve the beauty of surrounding environment and to contribute to emotional stability. They enrich the culture of human community and create new spaces for interaction between man and nature. This is a concept compatible with circulation of nature, and IS consistent with the penTlanent circulation of iron in the aspect of the recycling of iron. The author linked the changing process of fonnations to the concept of circulation in living organic bodies through changes over time in color and texture of weathering steel and contrast between weathering steel and stainless steel.

Initial Stage of Atmospheric Corrosion of Carbon and Weathering Steels in Thailand Climate

( K. Nii ),( C. Bhamornsut ),( L. Chotimongkol ),( E. Vutivat ),( R. Nakkhuntod ),( P. Jeenkhajohn ),( S. Suphonlai ) 한국부식방식학회 2003 Corrosion Science and Technology Vol.2 No.4

무도장 고내후성강을 이용한 건축물 외벽 마감의 시트간 접합방식유형과 방수성능평가에 관한 연구

양정필 대한건축학회 2003 대한건축학회논문집 Vol.19 No.1

The main purpose of this study is to investigate and evaluate the joint types of weathering steel derails in exterior wall. Usually rust influence bad impact against steel. So proper treatments against rust are necessary need in constructing buildings. But in case of weathering steel, rust(stabilized rust) rather protect steel and increase durability. The results of study are as follows: 1. The color of rust on weathering steel surface is changed onto dark-chocolate color, after serring up the sample model. And the difference of color by directions and parts is gradually reduced. 2. The rust stains on the surface by rebounded rains are not removed. So exterior wall of weathering steel must part from the floor level, about 30㎝. 3. The joint types of weathering steel are divided into 'butt joint type', 'overlapped joint type', and 'folded joint type'. 4. In aspect of waterproof performance, 'overlapped joint type' is superior to any other joint type.

합금원소 첨가가 구조용 강의 해변 내후성에 미치는 영향 연구 (Ⅰ) : Ca, Si의 첨가 효과 Ca and Si Effects

정환교,유장용,김규영 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.11

The objective of this study is to understand the effect of Si, on the corrosion property of the Ca-modified weathering steel and to determine the proper range of such alloying elements to maximize the effect of Ca on the corrosion resistance of the steel. The pH of a thin water film covering the steel was measured to evaluate the effect Ca addition on pH value. The electrochemical impedance spectroscopy (EIS) was employed to evaluate the corrosion resistance of the Ca-modified weathering steel. The characteristics of rust formed on the weathering steels having different alloy chemistry were examined. Analysis on the inclusion morphology and composition showed that the Ca-containing inclusions were mainly composed of Ca-Al-Mn-O-S,and Si was not founded in them except the specimen containing 0.6%Si. In distilled water, the Ca-modified specimens with or without Si showed higher pH values as Ca content was increased. The effect of Ca addition was not greatly affected by the addition of Si when the steel contained a proper Ca content of 50-70 ppm. In the impedance test, the specimens containing higher amounts of Ca showed higher polarization resistance, meaning better corrosion resistance. The analysis on the rust layers formed on the Ca-modified steel surface showed that the dense inner layer was mainly composed of a-FeOOH and y-FeOOH, whereas the loose outer layer was composed of ν-FeOOH and β-FeOOH. Fe₃O_(4) was distributed randomly throughout the rust layer. The specimens containing a high amount of Ca showed a dense and compact morphology, and the specimens containing Si also showed a dense and compact one. The result of Mossbauer analysis showed that more α-FeOOH was formed as Ca content was increased. (Received May 24, 2004)

Corrosion Behavior of Fe-Ni Bainitic Steel Through an Inverted Austempering Multi-Step Process for Weathering Steel Applications

Miftakhur Rohmah,Gusti Umindya Nur Tajalla,Gilang Ramadhan,Yunita Triana,Efendi Mabruri 한국부식방식학회 2024 Corrosion Science and Technology Vol.23 No.1

A Fe-Ni Bainitic steel as a weathering steel application was developed by combining its excellent mechanical properties and corrosion resistance in maritime environments. Nickel concentration (0.4-3 wt%) and inverted austempering multi-step (IAM) process were primary determinants of the microstructure of the Fe-Ni Bainitic steel. The initial austempering steel was performed at 300 o C for 600 seconds to obtain a partly bainitic transformation. The steel was heated again for 1800 s at 450 o C. The microstructure was comprised of ferrite, a blocky martensite/austenite island, and a homogeneous lath-shape bainite structure with widths ranging from 4.67 to 6.89 µm. The maximum strength, 1480 MPa, was obtained with 3 wt% nickel. In this study, corrosion behavior was investigated utilizing potentiodynamic and electrochemical impedance spectroscopy (EIS) tests. A higher nickel content in Fe-Ni Bainitic steel refined the grain size, improved the bainite fraction, lowered the corrosion rate to 0.0257 mmpy, and increased the charge transfer of film resistance to 1369 Ω.

무도장 내후성 강 교량의 밀폐형 박스거더 내부의 부식에 대한 고찰

마승환(Ma, Seung-Hwan),노영태(Noh, Young-Tai),장건익(Jang, Gun-Ik) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.4

내후성 강재는 대기환경에서 내식성이 우수하여 강교량의 재료로 많이 사용되고 있다. 그러나 내후성 강은 해수와 가까운 지역, 음지 및 습도가 높은 환경에서는 안정된 녹층이 형성되지 않고, 일반녹이 발생하고 있다. 따라서 열악한 대기 환경을 가지는 일본에서는 무도장으로 사용하지 않고, 녹안정화 처리를 하고 있는 상황이다. 그러나 국내에서 건설된 내후성 강은 대부분 무도장으로 건설되었고, 건습의 주기적인 반복이 일어나기 어려운 밀폐형 박스거더형으로 건설되었다. 특히, 한강수변위에 건설된 강교량의 경우, 수분의 증발, 온도차에 의한 결로 및 우수에 의한 체수 등으로 내후성강의 부동태 피막 형성에 해로운 영향을 미치고 있다. 이에 따라, 본 연구에서는 상수도 보호구역에 무도장 내후성 강으로 건설된 교량의 밀폐 형 박스거더 내부의 부식 특성을 분석하기 위하여, 육안에 의한 관찰, 셀로판 테이프 시험, 강재 두께 측정, 표면 부식 전위 측정, 채취한 녹의 전자현미경 분석 및 X선 회절 분석을 실시하였다. 분석을 통하여, 밀폐형 박스거더 내부에서 불안정녹층 이 관찰되었으며, 특히, 상부 및 하부 플랜지의 경우 우수에 의한 체수, 결로 및 제설제에 의한 영향 등으로 부식 정도가 심하게 관찰되었다. Weather proof steels are used for steel bridges due to its high corrosion resistance under atmospheric conditions. However, instead of forming stabilized rust layers, general rust occurs on weather proof steels under high humidity condition close to seawater or shady places. In Japan, therefore, they perform rust stabilization treatment instead of unpainted treatment due to severe atmospheric conditions. However, most of domestic weather proof steels were constructed unpainted in the form of closed box-girder, which makes the periodical repetition of dry and wet hard to occur. For the steel bridges constructed on the Han river, the evaporation of water, dew condensation due to temperature change, and stagnant water due to rain affect harmfully on the formation of passive film on weather proof steels. Thus, in this research, in order to analyze corrosion properties inside the closed box-girder for the unpainted weather proof steel bridge in the waterworks safety zone, multiple ways of analysis such as observation with eyes, cellophane-tape test, steel thickness measurement, surface corrosion potential measurement, electron microscope analysis, and X-ray diffraction analysis of the rust were performed. As a result, unstable rust layer was observed inside the closed box-girder, and severe corrosion was observed on the top and bottom of the flanges due to the effects of stagnant water caused by rain, dew condensation, and de-icing materials.

석조문화재의 풍화물성을 고려한 구조보강방법 연구

이동식,김현용 한국문화재보존과학회 2015 보존과학회지 Vol.31 No.4

본 연구에서는 석조문화재에 대한 금속보강재의 최소 개입을 통해 원형부재의 이차 훼손을 줄이고 , 동시에최대의 구조보강 효과를 얻을 수 있도록 제안된 실험을 통해 처리기술의 객관적 기준을 다음과 같이 설정하였다. 첫째, 금속보강재의 설계 기준은 석조문화재의 풍화도에 따라 보강재비의 산정이 이루어져한다. 둘째, 석조문화재의 원형이부분적으로 훼손되어 형태나 구조적으로 보강이 필요할 때 보형처리(구부재 + 신석재 접합)는 풍화등급이 높은 부재를기준으로 금속보강재 비율을 계획해야 한다. 본 연구를 바탕으로 석조문화재의 구조적인 안정을 꾀할 수 있는 조건을고려한 금속보강재 비율을 풍화영역별로 제시하면, 접합단면 대비 800kgf/cm2 이하는 0.13∼0.23, 800kgf/cm2 이상1200kgf/cm2 이하는 0.24∼0.28, 1200kgf/cm2 이상은 0.29∼0.5의 금속보강재비를 권장할 수 있다. 특히 더욱 세분화된풍화등급에 따른 금속보강재의 적용 여부는 석조물의 파괴계수와 금속보강재의 물성을 고려하여야 할 것으로 사료된다. At this, in this study, some tests were conducted to come up with a method to minimize intervention, to reduce the secondary damage to original materials, and to produce remarkable reinforcing effects. The followings show objective standards. The proportion of original material to steel reinforcement bar (the ratio of steel reinforcement bar) needs to be calculated in light of weathering intensity. Second, in the case of partial damage, prosthetic treatment is applied to add new stone materials to original materials. In that case, the ratio of steel reinforcement bar should be calculated based on material that is highly resistant to weathering. With the results of this study, it is possible to suggest conditions that can structurally stabilize stone cultural heritage, according to the weathering area. As a result, the ratio of steel reinforcement bars can be 0.13 to 0.23 in the case of 800kgf/cm2 or less, 0.24 to 0.28 in 800kgf/cm2 or higher, and 0.29 to 0.5 in 1200kgf/cm2 or higher. In particular, there is the need to take the coefficient of rupture of stone material and the properties of the steel reinforcement bar into account in cases of calculating the ratio of steel reinforcement bars according to weathering intensity.

STS 436 및 내후성 강에 대한 GMAW 용접에서 경도 변화에 따른 재료의 고온균열 성질변화 고찰 - EN 12072 G 18-8 Mn 용접와이어 사용에 따른 용접부의 변화에 대한 연구(2) -

이칠순(Chil-Soon Lee),김법헌(Bub-Hun Kim) 산업기술교육훈련학회 2012 산업기술연구논문지 (JITR) Vol.17 No.2

In industrial sites trains or vehicles have been used to transport products as a general transportation way. For saving transportation cost it can be the key to produce a storing facility that is lighter, more long-lasting, stronger, and safer as the condition of the same weight. A container doesn t ask high technology to make but allows to carry lots of loads safely. Therefore It s important to achieve automated mass production system. In this study, its purpose is to manufacture a container that is durable and strong against corruption. Thanks to the welding wire diluted on the welding parts, ferritic stainless steel, and components of the weathering steel. To achieve the goal, GMAW welding varied on welding speed, welding wire, and protective gas is applied under the condition that ferritic stainless steel and weathering steel are folded so as to make a durable container compared to a common container. Supposing to know the changes of welded materials through the analyze of components variation after the completion of welding of using EN 12072 G 18-8 Mn welding wire, it s possible to create a better product by applying proper welding condition that can decrease welding defects.

Atmospheric Corrosion Behavior of Weathering Steel Exposed to the Outdoors for 10 Years in Korea

Yoo, Y.R.,Choi, S.H.,Kim, Y.S. The Corrosion Science Society of Korea 2022 Corrosion Science and Technology Vol.21 No.4

Steel structures exposed to the outdoors experienced several types of corrosion, which may reduce their thickness. Since atmospheric corrosion can induce economic losses, it is important to consider the atmospheric corrosion behavior of a variety of metals and alloys. This work performed outdoor exposure tests for 10 years at 14 areas in Korea and calculated the atmospheric corrosion rate of weathering steel. This paper discussed the atmospheric corrosion behavior of weathering steel based on various corrosion factors. The average corrosion rates in coastal, industrial, urban, and rural areas were found to range from (2.83 to 4.23) ㎛/y, (2.99 to 4.23) ㎛/y, (1.72 to 3.14) ㎛/y, and (1.57 to 2.85) ㎛/y respectively. It should be noted that the maximum corrosion rate was about 6.0 times greater than the average corrosion rate. Regardless of the exposure sites, the color differences were increased, but the glossiness was reduced and there was no relationship between the corrosion rate and environmental factors and the glossiness.