• Title/Summary/Keyword: corrosion ratio

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Corrosion Behavior of Zirconium Alloys with Nb and Cr Addition (Nb 및 Cr 첨가에 따른 지르코늄 합금의 부식거동)

  • Kim, Yoon-Ho;Mok, Yong-Kyoon;Kim, Hyun-Gil;Lee, Jong-Hyeon
    • Korean Journal of Materials Research
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    • v.25 no.8
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    • pp.376-385
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    • 2015
  • The effects of Nb and Cr addition on the microstructure, corrosion and oxide characteristics of Zr based alloys were investigated. The corrosion tests were performed in a pressurized water reactor simulated-loop system at $360^{\circ}C$. The microstructures were examined using OM and TEM, and the oxide properties were characterized by low-angle X-ray diffraction and TEM. The corrosion test results up to 360 days revealed that the corrosion rates were considerably affected by Cr content but not Nb content. The corrosion resistance of the Zr-xNb-0.1Sn-yCr quaternary alloys was improved by an increasing Nb/Cr ratio. The crystal structure of the precipitates was affected by a variation of the Nb/Cr ratio. The Zr-Nb beta-enriched precipitates were mainly formed in the high Nb/Cr ratio alloy while $Zr(NbCr)_2$ precipitates were frequently observed in the low Nb/Cr ratio alloy. The studies of oxide characteristics revealed that the corrosion resistance was related to the crystal structure of the precipitate.

Application of Multiple Linear Regression to Predict Mechanical Properties of 316L Stainless Steel with Unspecified Pit Corrosion (불특정 공식손상을 가진 316L 스테인리스강의 기계적 물성치 예측을 위한 다중선형회귀 적용)

  • Kwang-Hu Jung;Seong-Jong Kim
    • Corrosion Science and Technology
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    • v.22 no.1
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    • pp.55-63
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    • 2023
  • The aim of this study was to propose a multiple linear regression (MLR) equation to predict ultimate tensile strength (UTS) of 316L stainless steel with unspecified pit corrosion. Tensile specimens with pit corrosion were prepared using a potentiostatic acceleration test method. Pit corrosion was characterized by measuring ten factors using a confocal laser microscope. Data were collected from 22 tensile tests. At 85% confidence level, total pit volume, maximum pit depth, mean ratio of surface area, and mean area were significant factors showing linear relationships with UTS. The MLR equation using these three significant factors at a 85% confidence level showed considerable prediction performance for UTS. Determination coefficient (R2) was 0.903 with training and test data sets. The yield strength ratio of 316L stainless steel was found to be around 0.85. All specimens with a pit corrosion presented a yield ratio of approximately 0.85 with R2 of 0.998. Therefore, pit corrosion did not affect the yield ratio.

Corrosion effects on tension stiffening behavior of reinforced concrete

  • Shayanfar, M.A.;Ghalehnovi, M.;Safiey, A.
    • Computers and Concrete
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    • v.4 no.5
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    • pp.403-424
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    • 2007
  • The investigation of corrosion effects on the tensile behavior of reinforced concrete (RC) members is very important in region prone to high corrosion conditions. In this article, an experimental study concerning corrosion effects on tensile behavior of RC members is presented. For this purpose, a comprehensive experimental program including 58 cylindrical reinforced concrete specimens under various levels of corrosion is conducted. Some of the specimens (44) are located in large tub containing water and salt (5% salt solution); an electrical supplier has been utilized for the accelerated corrosion program. Afterwards, the tensile behavior of the specimens was studied by means of the direct tension tests. For each specimen, the tension stiffening curve is plotted, and their behavior at various load levels is investigated. Average crack spacing, loss of cross-section area due to corrosion, the concrete contribution to the tensile response for different strain levels, and maximum bond stress developed at each corrosion level are studied, and their appropriate relationships are proposed. The main parameters considered in this investigation are: degree of corrosion ($C_w$), reinforcement diameter (d), reinforcement ratio (${\rho}$), clear concrete cover (c), ratio of clear concrete cover to rebar diameter (c/d), and ratio of rebar diameter to reinforcement percentage ($d/{\rho}$).

Effect of Austenitizing Ratio on the Delta Ferrite Volume Fraction and Corrosion Resistance of Shell Mold Cast SSC13 Elbow Fitting (셀 몰드 주조한 SSC13 엘보우 피팅 주강의 고용화율에 따른 델타 페라이트 분율 변화와 내부식특성)

  • Kim, Kuk-Jin;Lim, Su-Gun;Ju, Heong-kyu;Pak, Sung-Joon
    • Journal of Korea Foundry Society
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    • v.35 no.5
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    • pp.109-113
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    • 2015
  • In this study, the measurement of FN (ferrite volume fraction) and the solution annealing ratio at a temperature of $1130^{\circ}C$ were determined with 15A elbow fittings of shell cast SSC13, and the corrosion resistance with and without austenitizing solution annealing were investigated in comparison with AISI304. The delta ferrite phase was observed in the material due to the slow cooling effect of the shell mold casting. However, the delta ferrite phase decreased gradually with the solution annealing at a temperature of $1130^{\circ}C$. The hardness generally decreased with a heat treatment; however, its corrosion resistance was improved with the heat treatment. In addition, when a passivation treatment was applied, its corrosion ratio showed the lowest value. The pattern of general corrosion decreased due to the decrease in the delta ferrite phase with the solution annealing treatment. Consequently, it is suggested that the corrosion resistance of SSC13 elbow fittings can be improved by increasing the ratio of any solution annealing treatment used and by decreasing the ferrite phase. The relationship between the ratio of solution annealing and delta ferrite is expressed as follows: SA (solution annealing ratio,%) = 98 - FN (ferrite volume fraction, %).

Evaluation of Characteristic for SS400 and STS304 steel by Weld Thermal Cycle Simulation - 2nd Report: Corrosion Characteristics (용접열사이클 재현에 의한 SS400강 및 STS304강의 특성 평가 -제2보: 부식특성)

  • Ahn, Seok-Hwan;Choi, Moon-Oh;Kim, Sung-Kwang;Son, Chang-Seok;Nam, Ki-Wook
    • Journal of Ocean Engineering and Technology
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    • v.21 no.5
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    • pp.33-38
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    • 2007
  • The welding methods have been applied in the most structural products from multi-field of automobile, ship construction and construction, and so on. The structure steel must have enough strength of structure. In this study, SS400 steel and STS304 steel were used to estimate the corrosion characteristics of the weld thermal cycle simulated HAZ. To evaluate the corrosion characteristics, also, the materials with two conditions were used in 3.5% NaCl. The one is to the drawing with diameter of ${\Phi}10$ and the other is to the residual stress removal treatment. The electrochemical polarization test and immersion test were carried out. From test results, corrosion potential, corrosion current density, weight loss ratio and corrosion rate were measured. In the kinds of SS400 steels, corrosion potential of weld thermal cycle simulated specimens after the heat treatment showed somewhat the direction of noble potential. And in the base metal to be drawing weight loss ratio and corrosion rate occurred higher than the other kinds. In the kinds of STS304 steels, the result of base metal to be drawing was similar to results of SS400 steels, too. Two kinds of $750^{\circ}C$ and $1300^{\circ}C$ of weld thermal cycle simulation after the heat treatment were rather higher than the other kinds in weight loss ratio and corrosion rate.

An Experimental Study on the Reinforcement Corrosion in Concrete Using Granulated Blast Furnace Slag (고로슬래그 미분말을 사용한 콘크리트 내의 철근부식에 관한 실험적 연구)

  • 이동혁;김은겸;김영웅;김영철
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.761-766
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    • 2002
  • This paper was peformed to verify the effect that granulated blast furnace slag gets in reinforcement corrosion resistance about chloride ion that invade from outside. An experiment accelerated for the reinforcement corrosion through repeat of brine digestion and dry. Reinforcement corrosion investigated half cell potential method of measurement by ASTM C876 and corrosion area ratio. If granulated blast furnace slag metathesis ratio is high generally that looked the corrosion of reinforcement decreasing as a result that evaluate reinforcement corrosion by ASTM C876 canon in this research. It showed high resistance about reinforcement corrosion that use normal portland cement and increase the metathesis rate of granulated blast furnace slag, as a result that evaluate metathesis rate effect of granulated blast furnace slag according to cement kind. when the test piece split destroying, area rate of reinforcement corrosion showed about result of half cell potential measurement.

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A Study on the Characteristics of Reinforcing Steel according to Specification and Diameter (철근의 강종 및 직경 변화에 따른 부식특성에 관한 연구)

  • Lim, Jae-won;Jee, Nam-Yong;Yoon, Sang-Chun;Choi, Jin-man
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.11a
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    • pp.53-58
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    • 2003
  • Concrete structures move wholly with concrete and rebar, so they endure external force, but recently the embedded rebar in concrete has been corroded by environmental, physical and chemical factors, the embedded rebar corrosion influences concrete structure to deteriorate structure capacity. To revaluate effect to deterioration of concrete structure according to corrosion of rebar, the researcher mostly examined into corrosion rebar and complex relation of concrete. In that there are flexural strength deterioration of corrosion concrete structure and the bond strength of concrete. But It has not sufficiently studied about physical characteristic of corrosion rebar itself. In this study I will compare specification of rebar through corrosion experiment with corrosion ratio of rebar according to diameter and revaluate. And will investigate the effect to strength characteristic of rebar according to corrosion ratio.

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A Study on the Characteristics of Reinforcing Steel according to Specification and Diameter (철근의 강종 및 직경 변화에 따른 부식특성에 관한 연구)

  • 임재원;지남용;윤상천;최진만
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2003.05a
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    • pp.53-58
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    • 2003
  • Concrete structures move wholly with concrete and rebar, so they endure external force, but recently the embedded rebar in concrete has been corroded by environmental, physical and chemical factors. the embedded rebar corrosion influences concrete structure to deteriorate structure capacity. To revaluate effect to deterioration of concrete structure according to corrosion of rebar, the researcher mostly examined into corrosion rebar and complex relation of concrete. In that there are flexural strength deterioration of corrosion concrete structure and the bond strength of concrete. But It has not sufficiently studied about physical characteristic of corrosion rebar itself. In this study I will compare specification of rebar through corrosion experiment with corrosion ratio of rebar according to diameter and revaluate. And I will investigate the effect to strength characteristic of rebar according to corrosion ratio.

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Experimental Study on the Penetration Depth and Concentration of Corrosion Inhibitor Using Press-in Method Into the Inside of Concrete (콘크리트 내부로의 압입공법을 사용한 방청제의 침투깊이 및 농도에 관한 실험적 연구)

  • Cho, Hyeong-Kyu;Yoo, Jo-Hyeong;Lee, Han-Seung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.13 no.5 s.57
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    • pp.160-168
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    • 2009
  • After steel bar was corroded it removes concrete contaminated, it does steel bar corrosion protection, repairing method and corrosion inhibitor spreading method are difficult to secure corrosion protection performance. Accordingly, in this research before Research and Development to penetrate corrosion inhibitor to high pressure by steel bar position, it measures penetration depth through corrosion inhibitor high pressure penetration experiment and amount of nitrite by position and then it predicts penetration depth in accordance with water-cement ratio, pressure, pressure time and it computed water-cement ratio, pressure, pressure time to be more than 0.6 mol ratio of chloride ion and nitrite to have outstanding corrosion protection performance. As a result of experiment, water-cement ratio gives the biggest influence to penetration of corrosion inhibitor and also the more depth of specimen becomes deep, concentration of penetrated corrosion inhibitor does not equal and becomes low.

A Study on the Estimation of Steel Corrosion in Concrete Exposed under the Environment of Seawater (해양환경하에 방치한 콘크리트중의 철근의 부식 추정에 대한 연구)

  • 문한영;김성수;류재석
    • Magazine of the Korea Concrete Institute
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    • v.6 no.2
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    • pp.129-137
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    • 1994
  • This study was performed for the purpose of obtaining the fundamental data to establish the criterion of concrete deterioration and presuming steel corrosion of concrete structures under the environment of seawater. Steel embedded concrete specimens were exposed in seawater for 1year. The soluble chloride content in concrete, corrosion potential and steel corrosion were considered. The results show that soluble chloride content in concrete was decreased with lower water-cement ratio and with mineral admixtures. Half-cell potential is reduced with steel corrosion. Corrosion area ratio is correlative with half-cell potential.