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Hydrogen Induced Crack Propagation in Bainitic X70 Steel in Hydrogen Pressured Tensile Test
베이나이트계 X70강 수소가압분위기 인장시험의 수소취성균열 전파
Byung Hak Choe, Hyeon Su Jang, Bum Gyu Lee, Eui Soo Kim, Woo Sik Kim, Un Bong Baek, Sung Hoon Nam최병학, 장현수, 이범규, 김의수, 김우식, 백운봉, 남승훈
Korean J. Met. Mater. 2018;56(1):1-7. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.1
Abstract
This study investigated hydrogen induced cracking (HIC) of X70 steel, used for gas pipeline material, with a bainitic microstructure. The effect of hydrogen on the steel was investigated by tensiletesting in a high pressure hydrogen atmosphere, using OM, SEM and TEM analyses. The mechanisms of hydrogen-related cracking were represented as..... More
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Growth Rate of Gamma Prime Precipitates in Ni-Base Superalloy
니켈기 초내열합금의 감마프라임상의 성장거동
Junhyeob Oh, Daeyoung Jo, Hongkyu Kim, Jondo Yun오준협, 조대영, 김홍규, 윤존도
Korean J. Met. Mater. 2018;56(1):8-13. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.8
Abstract
The mechanical properties of nickel-base superalloys used in disk and blade materials for gas turbine engines can be maximized by controlling their microstructure, such as the size of precipitates. In this study, we investigated the size of gamma prime precipitates after age hardening heat treatment at 650-980 oC for 1-48..... More
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Development of Rare-Earth Element Based High Entropy Bulk Metallic Glasses
희토류 원소계 고엔트로피 벌크 비정질 합금 개발
Jinyeon Kim, Hyun Seok Oh, Jinwoo Kim, Eun Soo Park김진연, 오현석, 김진우, 박은수
Korean J. Met. Mater. 2018;56(1):14-25. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.14
Abstract
High entropy alloys (HEAs) are a relatively new class of metallic materials. HEAs lead to high mixing entropy and the formation of a simple solid solution rather than intermediate phases. This might be explained by the fact that the configurational entropy outweighs the enthalpy of formation of intermetallic compounds. Meanwhile,..... More
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Effect of Carbon Addition and Recrystallization on the Microstructure and Mechanical Properties of CoCrFeMnNi High Entropy Alloys
CoCrFeMnNi 고엔트로피 합금에서 탄소 첨가 및 재결정열처리가 미세구조 및 기계적 특성에 미치는 영향
Jun Yeong Ko, Jae Sook Song, Sun Ig Hong고준영, 송재숙, 홍순익
Korean J. Met. Mater. 2018;56(1):26-33. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.26
Abstract
The effect of carbon addition on the cast and rolled microstructures of CoCrFeMnNi high entropy alloys were studied. Both as-cast CoCrFeMnNi and CoCrFeMnNiC0.1 alloys have a dendritic microstructure. Small carbide particles were observed at the inter-dendritic region in the as-cast CoCrFeMnNiC0.1 and elongated-grained structure with aligned carbides were developed at..... More
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A Study on the Variation in Tensile Ductility of Porous Sintered Iron
다공성 소결 순철에서 인장연성의 변화에 관한 연구
Jae-Young Jung, Ho-Sang Sohn정재영, 손호상
Korean J. Met. Mater. 2018;56(1):34-39. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.34
Abstract
A model based on Irwin's approach to elastic-plastic deformation was applied to predict the tensile ductility of a sintered iron. The evaluation of this model using experimental results for porous sintered iron showed that tensile ductility depends not only on the pore volume fraction, but also the pore size and..... More
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Effect of Al Addition on the Microstructure, Tensile Properties, and Bendability of Extruded Mg-7Sn-1Zn Alloy
Al 첨가가 Mg-7Sn-1Zn 합금 압출재의 미세조직과 인장 및 굽힘 특성에 미치는 영향
Sang-Hoon Kim, Jong Un Lee, Ye Jin Kim, Jae Ok Choi, Jeong-Hun Lee, Sung Hyuk Park김상훈, 이종언, 김예진, 최재옥, 이정훈, 박성혁
Korean J. Met. Mater. 2018;56(1):40-48. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.40
Abstract
The effect of Al addition on the microstructure and mechanical properties of extruded Mg-Sn based alloy is investigated by adding 1 wt% Al to the Mg-7Sn-1Zn alloy and indirectly extruding the billets with and without the Al addition. The Al addition promotes dynamic recrystallization (DRX) behaviour during hot extrusion, which..... More
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Recovery of Fine Aluminum Hydroxide with High Whiteness Index from Low Quality
Bauxite Using Caustic Roasting and Water Leaching
Su Jin Kim, Jeong Il Lee, Kyu Sung Han, So Yeong Byun, Tam Tran, Myong Jun Kim
Korean J. Met. Mater. 2018;56(1):49-58. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.49
Abstract
A bauxite of low quality containing 6.75% reactive silica and 37.4% Al 2O 3 as gibbsite was roasted with additives including NaOH (caustic/total alumina molar ratio of 2-4:1) and CaO (CaO/total SiO 2 molar ratio of 0.5-3:1) at 300-1000 oC, producing calcines containing sodium aluminate (Na2O.Al 2O 3), silicates and hematite. Optimum conditions included roasting..... More
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Enhancement of the Hydrogen-Storage Characteristics of Mg by Adding Mg2Ni and Ni to MgH2 via High Energy Ball Milling in Hydrogen Atmosphere
Seong-Hyeon Hong, Young Jun Kwak, Myoung Youp Song
Korean J. Met. Mater. 2018;56(1):59-65. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.59
Abstract
In this work, Mg 2Ni and Ni were added to MgH 2 in order to improve the hydrogen-storage properties of Mg. A 94 wt% MgH 2+5 wt% Mg 2Ni+1wt% Ni (named 94MgH 2+5Mg 2Ni+1Ni) sample was prepared by milling in a hydrogen atmosphere in a planetary ball mill for 5 h. The Mg 2Ni was hydrided during..... More
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Charge Transport and Thermoelectric Properties of P-type Bi2-xSbxTe3 Prepared by Mechanical Alloying and Hot Pressing
Kyung-Wook Jang, Hyeok-Jin Kim, Woo-Jin Jung, Il-Ho Kim
Korean J. Met. Mater. 2018;56(1):66-71. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.66
Abstract
Bi 2-xSb xTe 3 (x = 1.4–1.7) solid solutions were synthesized by mechanical alloying (MA) and consolidated by hot pressing (HP), and their charge transport and thermoelectric properties were examined. The relative densities of the hot-pressed specimens were higher than 96% on average. As the Sb content was increased, the lattice constants decreased,..... More
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Infrared Spectra and Thermal Properties of Sodium Silicate Solutions
규산나트륨 수용액의 분자결합구조 및 열적특성 연구
Young Bok Ryu, Man Sig Lee류영복, 이만식
Korean J. Met. Mater. 2018;56(1):72-78. Published online 2018 Jan 1 DOI: https://doi.org/10.3365/KJMM.2018.56.1.72
Abstract
An inorganic binder is a good way to mitigate the environmental issues of organic binders containing phenol, formaldehyde, etc. One of the most representative materials in the field of inorganic moulding sand binders is a group of binder systems based on alkali silicate compounds, however, many aspects need to be..... More
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