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171 |
Investigation of Color Change in Cu-Zn Alloys by Reflectivity and Color Difference Analysis
반사도와 색 차 분석을 이용한 Cu-Zn 합금의 색 변화 고찰
Yeon Beom Jeong, Sung Hwan Hong, Hae Jin Park, Young Seok Kim, Jeong Tae Kim, Hoo Dam Lee, Yun Jung Hwang, Young Hoon Lee, Ki Buem Kim정연범, 홍성환, 박혜진, 김영석, 김정태, 이후담, 황윤중, 이영훈, 김기범
Korean J. Met. Mater. 2018;56(3):171-176. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.171
Abstract
The change in reflectivity of Cu-Zn alloys was investigated with the modulation of Zn content. The reflectivity of the prepared alloys were compared with pure copper and divided into wavelength regions corresponding to blue, green, yellow, and red colors. As the amounts of Zn increased, the difference in reflectivity of..... More
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177 |
Effect of Pre-Straining on the High-Cycle Fatigue Properties of Hot-Rolled Steel Sheets for Automotive Structural Uses
자동차 구조용 열연강판의 고주기 피로 특성에 미치는 전변형 효과
Dong-Woog Ha, Chang-Yeol Jeong하동욱, 정창열
Korean J. Met. Mater. 2018;56(3):177-186. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.177
Abstract
The drive towards weight reduction in the automotive industry has led to the use of high strength steel sheets for structural applications. Pressing and stamping are important processes in automotive production and result in additional straining on the vehicle body and chassis sheet material. It is therefore important to have..... More
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187 |
Effects of Manufacturing Conditions on Tensile Fracture Behaviors in Hyper-Eutectoid Steel Wires
과공석 강선에서 공정조건이 인장파단 거동에 미치는 영향
Kang Suk An, Jung Hoon Park, Won Jong Nam안강석, 박정훈, 남원종
Korean J. Met. Mater. 2018;56(3):187-196. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.187
Abstract
This study investigated the effects of manufacturing conditions, such as patenting temperature and drawing strains, on the tensile fracture behaviors, especially on reduction of area (RA), of hyper-eutectoid steel wire. Steel wires with the chemical compositions of Fe-0.92C-1.3Si-0.6Mn-0.3Cr (wt%), were austenitized at 900 °C for 3 min and isothermally transformed..... More
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197 |
Microstructure of Rhenium Coatings Deposited by CVD on Graphite and Mo Substrates
흑연 및 Mo 기판 위에 CVD 성장된 Re 코팅층의 미세조직
Sun Kyu Lee, Dong Yun Nam, Nam Ho Bae, Sung Taek Lim, Yong-Jun Oh이선규, 남동윤, 배남호, 임성택, 오용준
Korean J. Met. Mater. 2018;56(3):197-204. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.197
Abstract
Rhenium coatings were fabricated on a graphite substrate at 1100 and 1250 oC and a molybdenum substrate at 1150 and 1250 oC by chemical vapor deposition (CVD) using ReCl5 precursor, and the effects of deposition temperatures and substrates on microstructure and crystal orientation were investigated. The rhenium coating on graphite..... More
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205 |
Efficacy of Acid Cleaning on the Deoxidation of Titanium Powder Using Calcium
Chon-Il Hong, Jae-Won Lim
Korean J. Met. Mater. 2018;56(3):205-209. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.205
Abstract
The optimum acid cleaning conditions for removing CaO formed by the reaction of Ca with Ti powder were investigated in this study. In this experiment, we used Ti powders composed of irregular polygonal Ti particles with average sizes of 125 mm and 250 μm. Ca granules were charged at 50%..... More
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210 |
Effect of Anisotropy on Springback Prediction in Forming of 590MPa High Strength Steel
590MPa급 고강도강의 성형 시 스프링백 예측 정확도에 미치는 판재이방성의 영향
Se Kye Park, Eung Ryul Baek, Nokeun Park박세계, 백응률, 박노근
Korean J. Met. Mater. 2018;56(3):210-220. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.210
Abstract
Material parameters, extracted from mechanical behavior in a uniaxial direction without considering anisotropy in the rolling direction, are commonly used when doing forming analysis. However, when these material parameters are used for the forming analysis of a material which has large anisotropy, inaccurate analysis results can be obtained. In this..... More
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221 |
Effect of Hot Forging and Heat Treatment on the Microstructure and Mechanical Properties of Cr Steel
Cr강의 미세조직과 파괴인성에 미치는 열간단조 및 열처리 공정의 영향
Dong Jun Lee, Yong-Nam kwon, Min Suk Kim, Ga Eun Ku, Sang Hyun Heo, Nam Yong Kim, Jin-Mo Lee이동준, 권용남, 김민석, 구가은, 허상현, 김남용, 이진모
Korean J. Met. Mater. 2018;56(3):221-226. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.221
Abstract
In this study, the effects of hot forging and heat treatment (quenching and tempering) of cast Cr alloy steel on the microstructures and mechanical properties were investigated. The hot forging was performed at a compressive ratio 0.5 at 1,250 oC. The heat treatment process was quenching (860 oC for 2..... More
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227 |
Heat Dissipation Analysis of High-Power, Multi-Chip LED Bulbs
고 출력, 멀티 칩 LED 벌브에서 방열 거동 해석
Cheol-Hee Moon문철희
Korean J. Met. Mater. 2018;56(3):227-234. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.227
Abstract
To ensure the reliability of high-power light-emitting diode (LED) bulbs, temperature management is very important, including reduction of the junction temperature on the LED chip and enhancing outward thermal dissipation. Simulation can be an effective tool for predicting the temperature distribution over all bulbs, which enables a quantitative analysis. In..... More
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235 |
Bridge Burst Characteristics of Aluminum and Copper Thin-Film Bridges in Electrical Initiation Devices
Kyoungjin Kim, Kyu-Hyoung Kim, Seung-gyo Jang
Korean J. Met. Mater. 2018;56(3):235-243. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.235
Abstract
The optimal design of electrical initiation devices for explosive charges and other high energy materials critically depends on the bridge burst or the electrical explosion of the thin-film metallic bridges. It is therefore quite important to select the right material with suitable explosion properties for the metallic bridge film. However,..... More
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244 |
Comparison of the Hydrogen Release Properties of Zn(BH4)2-Added MgH2 Alloy and Zn(BH4)2 and Ni-Added MgH2 Alloy
Myoung Youp Song, Young Jun Kwak
Korean J. Met. Mater. 2018;56(3):244-251. Published online 2018 Mar 6 DOI: https://doi.org/10.3365/KJMM.2018.56.3.244
Abstract
Samples with compositions of 99 w/o MgH 2+1 w/o Zn(BH 4) 2 (designated MgH 2-1Zn(BH 4) 2) and 96 w/o MgH 2+2 w/o Zn(BH 4) 2+2 w/o Ni (designated MgH 2-2Zn(BH 4) 2-2Ni) were prepared by milling in a planetary ball mill in a hydrogen atmosphere (reaction-involving milling). The hydrogen release properties of MgH 2- 1Zn(BH 4) 2 and MgH 2-2Zn(BH 4) 2-2Ni were compared. A larger quantity..... More
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