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논문 : 제조공정 ; 분무성형에서의 공정변수의 최적화 (1) -초기분무온도의 제어에 관하여
이재철 ( Jae Chul Lee ),석현광 ( Hyun Kwang Seok ),신돈수 ( Don Soo Shin ),이호인 ( Ho In Lee ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
Effect of the initial melt temperature on the microstructure of the sprayformed 2014 Al billet was studied with particular emphasis on the effect of superheating on the liquid fraction(FL) in the sprayed droplets. In order to determine the average liquid fraction within the sprayed droplets, the cooling rate and the flight time of droplets were calculated. The measured cooling rate of droplets was in the vicinity of ~104℃/sec and the flight time before impinging the preform ranges from 6 to 9 msec depending on the size of droplets. The obtained results from the experiments were in good agrement with those of theoretical models by P. Grant et al. and/or Lee et al. The liquid fraction of droplets did not vary significantly with the initial melt temperature such that FL was calculated to be 24% when Ti = 800℃ while FL = 19.5% when Ti = 720℃, resulting in considerable amount of porosity within the preform. Such a result indicates that the initial melt temperature control may not be effective for fabricating preforms with a minimal amount of porosity.
7XXX계 단조재의 피로 및 파괴인성에 미치는 제조공정의 영향
이오연,임재규,송기홍,손영일,은일상,신돈수 ( O . H . Lee,J . K . Lim,K . H . Song,Y . I . Son,I . S . Eun,D . S . Shin ) 한국열처리공학회 1996 熱處理工學會誌 Vol.9 No.3
The purpose of this study is to investigate the effect of impurity level and fabrication processes on the strength, fracture toughness and fatigue resistance of 7075, 7050 and 7175 high strength aluminum forgings. It has been verified that plane strain fracture toughness and fatigue characteristics of a specially processed 7175S-T74 alloy is superior to a conventionally processed 7075-T6/T73, 7050-T74 and 7175-T74 alloys. These beneficial effects primarily arise from two view points, i.e., the effect of reducing the impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as Al_7Cu₂Fe and Mg₂Si. Futher reduction of the amount of nonequilibrium second phase particles has been observed by applying a special fabrication process.
서승일(Seo Seung Il),김진태(Kim Jin Tae),박일철(Park Il Chul),이동헌(Lee Dong Hun),신돈수(Shin Don Su) 한국철도학회 1999 철도저널 Vol.2 No.2
Based on the development of designed technology for aluminum carbody, the prototype aluminum carbody has been constructed. All extrusion profiles required for the carbody has been produced and their quality has also been proven. For sound construction, welding technology to join aluminum extrusion profiles has been developed and jigs for precise assembly of blocks have been made. The aluminum carbody for urban subway train has been completed with the required chamber being set and the welding deformations being constrained by jigs. The safety of the carbody structure has also been proven by the static load test. And also, painting technology has been developed and the surface of the carbody has been pre-treated and painted. The developed technology to construct the aluminum carbody can be used in mass production of aluminum cars ordered by domestic and foreign customers.