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Ramjet 고속 추진체용 Alloy 718 합금 노즐 단조품 개발
박노광,김정한,김남용,이채훈,염종택,홍재근,백동규,최성규,Park, Nho-Kwang,Kim, Jeoung-Han,Kim, Nam-Yong,Lee, Chae-Hoon,Yeom, Jong-Taek,Hong, Jae-Keun,Baek, Dong-Kyu,Choi, Sung-Gyu 한국군사과학기술학회 2008 한국군사과학기술학회지 Vol.11 No.4
Alloy 718 nozzle component was manufactured by hot forging and electron beam welding process. In this process, 718 billets produced in domestic company were used and evaluated. Before performing industrial scale hot forging, small size hot compression tests were carried out under various process conditions and then microstructural evaluations were analyzed. Using the results, FEM simulations were performed in order to optimize the hot working process. After hot working, forged work-pieces were machined and welded by electron beam. Final nozzle components were heat treated and their microstructure and mechanical properties were investigated.
Ti-6Al-4V합금의 열간 후방압출에 대한 성형 안정성 평가모델의 고찰
염종택,박노광,이유환,신태진,황상무,홍성석,심인옥,이종수,Yeom Jong-Taek,Park Nho-Kwang,Lee You-Hwan,Shin Tae-Jin,Hwang Sang-Mu,Hong Sung-Suk,Shim In-Ok,Lee Chong-Soo 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.3
The metal forming behavior of Ti-6Al-4V tube during hot backward extrusion was investigated with various forming stabilities or instabilities criteria. that is, Ziegler's instability criterion, dynamic materials model(DMM) stability criteria and Rao's instability criterion. These approaches also were coupled to the internal variables generated from FE simulation. In order to validate the reliabilities of three criteria, hot backward extrusions for Ti-6Al-4V tube making were carried out with different backward extrusion designs. The useful model for predicting the forming defects was suggested through the comparison between experimental observations and simulation results.
Ti-10wt.%Al-xMn 분말합금의 Mn첨가에 따른 소결특성 평가
신기승,현용택,박노광,박용호,이동근,Shin, Gi-Seung,Hyun, Yong-Taek,Park, Nho-Kwang,Park, Yong-Ho,Lee, Dong-Geun 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.3
Titanium alloys have high specific strength, excellent corrosion and wear resistance, as well as high heat-resistant strength compared to conventional steel materials. As intermetallic compounds based on Ti, TiAl alloys are becoming increasingly popular in the aerospace field because these alloys have low density and high creep properties. In spite of those advantages, the low ductility at room temperature and difficult machining performance of TiAl and $Ti_3Al$ materials has limited their potential applications. Titanium powder can be used in such cases for weight and cost reduction. Herein, pre-forms of Ti-Al-xMn powder alloys are fabricated by compression forming. In this process, Ti powder is added to Al and Mn powders and compressed, and the resulting mixture is subjected to various sintering temperature and holding times. The density of the powder-sintered specimens is measured and evaluated by correlation with phase formation, Mn addition, Kirkendall void, etc. Strong Al-Mn reactions can restrain Kirkendall void formation in Ti-Al-xMn powder alloys and result in increased density of the powder alloys. The effect of Al-Mn reactions and microstructural changes as well as Mn addition on the high-temperature compression properties are also analyzed for the Ti-Al-xMn powder alloys.
Waspaloy 터빈디스크의 열간 단조시 결정립분포 해석에 관한 연구
염종택,이종수,김정한,이동근,박노광,Yeom, Jong-Taek,Lee, Chong-Soo,Kim, Jeoung-Han,Lee, Dong-Geun,Park, Nho-Kwang 한국군사과학기술학회 2006 한국군사과학기술학회지 Vol.9 No.2
The microstructure evolution during a hot forging of Waspaloy was investigated using the recrystallization model and FEM simulation. In order to obtain an uniform microstructure, hot forging was carried out by two step. The change of grain size during hot forging has a deep connection with dynamic recrystallization behavior. Avrami-type constitutive equation for the dynamic recrystallization was implemented into an user subroutine of 2D FE simulator. The evolution of grain structure in the two-step forging of Waspaloy was simulated using the 2D FEM user-subroutine. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.