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API 강재에 첨가된 미량의 합금원소(Cr, Mo)가 CO2 포화염수 환경 내 부식거동에 미치는 영향
윤덕빈,방혜린,김완근,김성진 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.12
This study examined the effects of minor alloying elements (Cr and Mo) on the corrosion behaviorsof API grade steel in CO2-saturated near-neutral aqueous solutions. Various experimental and analyticalmethods were applied to gain insights into the underlying CO2 corrosion mechanism of the steels. The findingsrevealed that steel with a minute quantity of Mo (0.1 ~ 0.15 wt%) exhibited the lowest corrosion currentdensity and the highest polarization resistance. This outcome can be primarily attributed to the formationof a thin layer of Mo-based oxides/hydroxide, covered with a fine FeCO3 scale, consequently enhancingcorrosion resistance in CO2 environments. On the other hand, the addition of Cr (0.4 ~ 0.5 wt%) in combinationwith Mo resulted in degraded corrosion resistance due to the competitive precipitation of amorphous Cr(OH)3and crystalline FeCO3. This led to an uneven interface and the growth of FeCO3 particles, consequentlyreducing polarization resistance and increasing the corrosion rate. Based on the obtained results, it isrecommended that cost-effective steels for CO2 transportation can be developed by adding a small amount ofMo along with a higher quantity of Cr. This optimized combination of alloying elements is expected tosignificantly improve the anti-corrosion performance of the steel in near-neutral brine environments with CO2.
해양구조용 18Mn(V, Mo)강 내 Cr 첨가가 해수환경 내 부식-마모 복합거동에 미치는 영향
윤덕빈,박진성,이상철,최종교,김성진 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.9
The objective of this study was to examine the wear-corrosion behavior of 18Mn(V, Mo) steel, whichhad a minor amount of Cr addition (< 3 wt%), in an artificial seawater environment, and compare it toconventional carbon steel. A variety of electrochemical experiments, including linear polarization resistance,impedance spectroscopy, and galvanostatic polarization, were conducted, along with weight lossmeasurements after immersion and wear-corrosion testing. These tests aimed to determine the staticcorrosion and wear-corrosion mechanisms of 18Mn(V, Mo) steel with respect to Cr addition. The results ofthis study indicated that the addition of Cr to 18Mn(V, Mo) steel refined the V4C3 particles in themicrostructure, which led to an increase in surface hardness. Moreover, the 18Mn(V, Mo) steel with Craddition exhibited the lowest corrosion and corrosion-wear losses, compared to 18Mn(V, Mo) steel without Crand conventional carbon steel. This beneficial effect was primarily attributed to the formation of a thin Crenrichedcorrosion scale that adhered to the underlying steel. This corrosion scale served as a protectivebarrier against the penetration of corrosive species and as a lubricant for mechanical wear. The 18Mn(V, Mo)steel with Cr addition has potential application in various industrial fields, particularly in marine and offshoreenvironments, owing to its low corrosion-induced wear loss rate in a brine environment.
소둔 및 용접후열처리가 슈퍼 오스테나이트계 스테인리스강의 부식거동에 미치는 영향
윤덕빈 ( Duck Bin Yun ),박진성 ( Jin Sung Park ),조동민 ( Dong Min Cho ),홍승갑 ( Seung Gab Hong ),김성진 ( Sung Jin Kim ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.6
The effect of two different annealing temperatures on the level of the second phase precipitated in the microstructure and the corrosion behaviors of super austenitic stainless steel were examined. The sample annealed at a higher temperature had a significantly lower fraction of the sigma phase enriched with Cr and Mo elements, showing more stable passivity behavior during the potentiodynamic polarization measurement. However, after the welding process with Inconel-type welding material, severe corrosion damage along the interface between the base metal and the weld metal was observed regardless of the annealing temperature. This was closely associated with the precipitation of the fine sigma phase with a high Mo concentration in the unmixed zone (UMZ) during the welding process, leading to the local depletion of Mo concentrations around the sigma phase. On the other hand, the fraction of the newly precipitated fine sigma phase in the UMZ was greatly reduced by post-weld heat treatment (PWHT), and the corrosion resistance was greatly improved. Based on the results, it is proposed that the alloy composition of welding materials and PWHT conditions should be further optimized to ensure the superior corrosion resistance of welded super austenitic stainless steel.
탄소강 및 해드필드강의 파이프 조관에 따른 침식부식 거동에 대한 비교연구
김성진,윤덕빈,박진성,이상철,최종교,황중기 한국부식방식학회 2022 Corrosion Science and Technology Vol.21 No.3
Erosion-corrosion behaviors of Hadfield steel under a neutral aqueous environment with fine SiO2 particles were examined and compared with those of conventional carbon steel. A range of electrochemical experiments (potentiodynamic polarization, linear polarization, and impedance), immersion test, and slurry pot test (i.e., erosion-corrosion test) were performed. Results showed that the Hadfield steel composed of austenitic matrix with (Fe,Mn)-based carbide had lower corrosion potential and higher corrosion current density than carbon steel with a typical ferrite/pearlite structure. In addition, pipe forming increased total corrosion rates (i.e., pure corrosion and erosion-enhanced corrosion rates). Nevertheless, the erosion-corrosion rate of Hadfield steel was much smaller. Morphological observation showed that local damage in the form of a crater by erosion-corrosion was more noticeable in carbon steel. The higher resistance of Hadfield steel to erosion-corrosion was attributed to its lower total erosion rates (i.e., pure erosion and corrosion-enhanced erosion rates) highly depending on surface hardness. This study suggests that Hadfield steel with higher resistances to flowing erosion-corrosion in an aqueous environment can be applied widely to various industrial fields.
염수환경 내 해드필드강 용접열영향부의 부식 및 침식-부식 거동에 미치는 Cr 첨가의 영향
진승우,박진성,윤덕빈,이상철,최종교,오민석,김성진 대한금속·재료학회 2023 대한금속·재료학회지 Vol.61 No.12
The corrosion and erosion-corrosion behaviors in the weld heat-affected zone (HAZ) of Hadfieldsteels with varying Cr contents (1, 2, and 3 wt%) were examined. Various experimental methods, includingelectrochemical polarization, impedance, and weight loss measurements, were utilized. Two types of isothermalheat treatments were conducted in a box furnace to simulate the intercritical HAZ, known to be themost vulnerable region in terms of mechanical properties and environmental stabilities, and large-scalesamples for the erosion-corrosion experiment were fabricated. The results showed that increasing the Crcontent improved the resistance to corrosion and erosion-corrosion, but there was an inflection point whereadding more Cr had the opposite effect. Up to 2 wt%, a higher resistance was exhibited owing to the formationof a thin and protective oxide scale enriched with Cr that adhered to the steel surface. On the other hand,adding 3 wt% of Cr resulted in decreased resistance. This was due to the formation of coarse M7C3 (M: Cr)precipitated along the grain boundary, which caused the development of a thick and unstable oxide scale thatdetached locally. Based on these findings, it is essential to optimize the Cr content to ensure a high resistanceto corrosion and erosion-corrosion in the HAZ of Hadfield steel.
초고강도급 자동차용 강재 내 ε-carbide (Fe<sub>2.4</sub>C)가 부식 및 수소확산거동에 미치는 영향
박진성 ( Jin-seong Park ),윤덕빈 ( Duck Bin Yun ),성환구 ( Hwan Goo Seong ),김성진 ( Sung Jin Kim ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.5
Effects of ε-carbide (Fe<sub>2.4</sub>C) on corrosion and hydrogen diffusion behaviors of ultra-strong steel sheets for automotive application were investigated using a number of experimental and analytical methods. Results of this study showed that the type of iron carbide precipitated during tempering treatments conducted at below A<sub>1</sub> temperatures had a significant influence on corrosion kinetics. Compared to a steel sample with cementite (Fe<sub>3</sub>C), a steel sample with ε-carbide (Fe<sub>2.4</sub>C) showed higher corrosion resistance during a long-term exposure to a neutral aqueous solution. In addition, the diffusion kinetics of hydrogen atoms formed by electrochemical corrosion reactions in the steel matrix with ε-carbide were slower than the steel matrix with cementite because of a comparatively higher binding energy of hydrogen with ε-carbide. These results suggest that designing steels with fine ε-carbide distributed uniformly throughout the matrix can be an effective technical strategy to ensure high resistance to hydrogen embrittlement induced by aqueous corrosion.
Zn-Al-Mg 합금도금강판의 헤어라인 처리가 표면흑색화 및 열확산도에 미치는 영향
박진성(Jin Sung Park),윤덕빈(Duck Bin Yun),김상헌(Sang Heon Kim),김태엽(Tae Yeob Kim),김성진(Sung Jin Kim) 한국표면공학회 2023 한국표면공학회지 Vol.56 No.1
The effects of hairline treatment on surface blackening and thermal diffusion behaviors of Zn-Al-Mg alloy coated steel sheet were evaluated by the three-dimensional surface profiler and laser-flash technique. The metallographic observation of coating damages by hairline treatments showed that several cracks were initiated and propagated along the interface between primary Zn/eutectic phases. As the hairline processing became more severe, the crack occurrence frequency in eutectic phase of coating layer and the surface roughness increased, which had a proportional relationship with the level of blackening on the coating surface. In addition, the higher interfacial areas of the blackened coating surface, caused by the hairline process, led to an increase in thermal diffusivity and conductivity of the coated steel sheet. On the other hand, when the coating damage by hairline treatment was excessive and the steel substrate was exposed, there was little difference between the thermal diffusivity/conductivity of the untreated sample though the blackening degree was higher than that of untreated sample. This work suggests that the increase in the surface areas of the coating layer without exposure to steel substrate through hairline treatment can be one of the effective technical strategies for the development of Zn-Al-Mg alloy coated steel sheets with higher blackening level and thermal diffusivity.
김정선(Jung Seon Kim),박영덕(Young Duk Park),윤덕빈(Duk Bin Yoon),배성민(Sung Min Bae) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4
In this paper, we present the hitting noise generation mechanism of discharge valve on swash-plate type compressor. Also we found primary parameters which affect the hitting noise of discharge valve. Main factors of operating noise were identified by both FEA of internal component and acoustic cavity resonance of discharge chamber as well as experimental validation. According to this study, operating noise of swash-plate type compressor could be improved obviously by optimal design of discharge valve system and the hardness of disc rubber. Finally, based on this study, we could reduce clearly operating noise of compressor and hitting noise mechanism of swash-plate type compressor was studied.