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Twin roll strip casting 공정으로 제조된 Al 3527K 합금의 인장 및 피로 변형 거동
함기수(G. S. Ham),백민석(M. S. Baek),어광준(K. J. Euh),임영목(Y. M. Rhyim),이기안(K. A. Lee) 한국소성가공학회 2016 한국소성가공학회 학술대회 논문집 Vol.2016 No.4
This study investigated tensile and fatigue properties of Al 3527K alloy manufactured by strip casting process. Al 3527K alloy (as strip casted (F material)) produced by twin roll strip casting and H heat treated (480°C, 6hr, AC) alloy were examined and compared. Microstructure observation results revealed that both alloys (F and H) featured rapid solidification microstructures. In addition, both alloys were identified to be composed of Al, Al6(Mn, Fe) and AlFeMnSi phases. As H heat treatment was applied, Al 3527K-H alloy formed a more even phase distribution than Al 3527K-F alloy. The tensile properties showed that H heat treatment resulted in increase of strength and decrease of elongation. In tensile fracture surface observation, both alloys showed typical ductile fracture modes. The F alloy was measured to have a dimple size of 6.8㎛ on average, and the H alloy measured 4.2㎛ on average in fracture surfaces. High-cycle fatigue tests were performed using ISTRON 8501, and the test conditions were stress ratio R=0.1, 10 Hz at room temperature. The fatigue limit showed that H heat treatment resulted in increase of fatigue properties at all stress condition. Furthermore, F alloy featured a larger deviation in fatigue life in all identical stress conditions compared to the O alloy. This study also discussed the fatigue deformation behavior of Al 3527K alloy manufactured by strip casting through the abovementioned mechanical properties as well as the tensile and fatigue fractographies.
Fe-Cr-B 계 합금 폭발용사 코팅층의 미세구조와 마모에 의한 표면 비정질상 생성
김문철,박찬경,진현우,임영목 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.6
Thermal spray coating layers were prepared on the carbon steel plates with iron-chrome-boron alloy powders using a detonation gun under various fuel gas contents. The coating layer was composed of Fe rich Fe-Cr solid solution and (Cr. Fe)_xB particles, which had relatively a tow friction coefficient such as 0.05 and showed high wear resistance. The transition from crystalline to amorphous phase occurred during the wear treatment. TEM observation revealed that Fe-Cr solid solution phase with super-saturated B and Si was one of the main contributors for the transition. Oxide inclusions formed at an excess fuel gas condition may impede the crystalline to amorphous transition by lowering the solute content in Fe-Cr solid solution phase.
초미립 Fe-Cr-B 합금 용사코팅층의 미세조직과 상형성
김문철,박찬경,진현우,임영목 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.11
High boron containing Fe-Cr alloy powder has been investigated in this research as to its microstructure evolution by the rapid solidification in thermal spraying process. The Fe-Cr alloy powder consists of Cr-rich metal borides, such as Cr_(1.65)Fe_(0.35)B_(0.96) and Cr₂B, within Fe-Cr solid solution matrix phase. In the alloy powder, the boron content in the matrix phase was extremely low. Boron was supplied to the matrix Fe-Cr solid solution phase by the thermal dissolution of Cr-rich boride particles during the thermal spraying. Cross-sectional TEM observation on the coatings indicates that the coated layer is composed of equiaxed nanocrystalline Fe-Cr solid solution phase and boride particles. The formation of equiaxed nanocrystalline phase indicates that large undercooling could be attained during the rapid solidification of thermal spraying process.