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박동성 ( Dongsung Park ),전중환 ( Joong-hwan Jun ),이민하 ( Min-ha Lee ),이석재 ( Seok-jae Lee ) 한국열처리공학회 2017 熱處理工學會誌 Vol.30 No.4
In the present study, we investigated the optimal austenitizing temperature of high-alloyed tool steels from an industrial point of view. Austenitizing temperatures for manufacturing 25 commercial tool steels were surveyed with their alloy compositions. The relationship between the austenitizing temperatures and the critical equilibrium temperatures by thermodynamic-based calculation was analyzed and a correlation was found. Based on the austenitizing temperatures of 25 commercial tool steels and the thermodynamic calculation results, we proposed a simple equation to predict an optimal austenitizing temperature to achieve superior mechanical properties of high-alloyed tool steels. The applicability of the proposed equation was experimentally validated with a new developed tool steel. (Received May 12, 2017; Revised May 24, 2017; Accepted May 30, 2017)
김근학 ( Keunhak Kim ),박동성 ( Dongsung Park ),전중환 ( Joong-hwan Jun ),이민하 ( Min-ha Lee ),이석재 ( Seok-jae Lee ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.4
High temperature flow behaviors of Fe-Cr-Mo-V-W-C tool steel were investigated using isothermal compression tests on a Gleeble simulator. The compressive test temperature was varied from 850 to 1,150℃ with the strain rate ranges of 0.05 and 10 s<sup>-1</sup>. The maximum height reduction was 45%. The dynamic softening related to the dynamic recrystallization was observed during hot deformation. The constitutive model based on Arrhenius-typed equation with the Zener-Hollomon parameter was proposed to simulate the hot deformation behavior of Fe-Cr-Mo-V-W-C steel. An artificial neural network (ANN) model was also developed to compare with the constitutive model. It was concluded that the ANN model showed more accurate prediction compared with the constitutive model for describing the hot compressive behavior of Fe-Cr-Mo-V-W-C steel. (Received June 18, 2018; Revised June 26, 2018; Accepted July 6, 2018)
아공정 Al-Si-Cu-Mg 합금의 액상선 온도 곡선 예측
김근학 ( Keunhak Kim ),박동성 ( Dongsung Park ),오승진 ( Seung-jin Oh ),전준협 ( Junhyub Jeon ),윤상일 ( Sang-il Yoon ),김기선 ( Ki-sun Kim ),김태영 ( Tae-young Kim ),이석재 ( Seok-jae Lee ) 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.6
In the present study we proposed new equations to predict the liquidus temperature curve for hypoeutectic Al-Si-Cu-Mg alloy. A thermodynamic simulation was carried out to calculate the liquidus temperature, eutectic temperature and eutectic Si concentration with different Si, Cu, and Mg contents in hypoeutectic Al-Si alloys. Regressed equations were derived using the thermodynamic simulation results by multiple regression analysis. The proposed equations were compared with the equations reported previously by other researchers and agreed better with the experimental data. The addition of Cu and Mg lowered the eutectic temperature. The eutectic Si concentration was decreased by adding Cu whereas that was increased by adding Mg. Al-Si binary phase diagram was successfully predicted with a consideration of the effect of Cu and Mg addition by using the proposed equations. (Received October 2, 2018; Revised October 15, 2018; Accepted November 6, 2018)
핫 프레스에 의한 TiNi/Al606l 형상기억 복합재료의 최적 제조공정 및 기계적 특성에 관한 연구
박영철,박동성 동아대학교 생산기술연구소 2000 生産技術硏究所硏究論文集 Vol.5 No.2
핫 프레스를 이용한 TiNi/A16061 형상기억 복합재료의 제조조건을 결정하기 위하여 직교배열표에 의한 일부실험법을 이용하였으며, 최적의 조건하에서 다양한 섬유의 함유량을 가진 TiNi/A16061 형상기억 복합재료를 제조하였다. 섬유의 체적함유량이 3.2%, 5.2%, 7%의 형상기억 복합재료에 대하여 상온 및 고온에서 인장실험을 실시하였다. 또한, TiNi/A16061 형상기억 복합재료의 미시적 손상기구를 파악하기 위하여 음향방출기법을 적용하였으며, amplitude와 rise time이 유효한 파라미터임을 확인하였다. Orthogonal array is used to obtain the optimum processing conditions of TiNi shape memory alloy(SMA) fiber reinforced 6061 aluminum matrix composites made by hot press. We could make a TiNi/A16061 shape memory composites under optimum conditions with various fiber volume fraction. Mechanical properties of TiNi/A16061 shape memory composites are investigated experimentally. Acoustic emission technique was used to understand microscopic failure mechanism under static loading for TiNi/A16061 composite. It was found that the key parameters affecting initial crack propagation are amplitude and rise time