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Al 7003 합금의 인장 및 피로 특성에 미치는 열처리(T5, T6)의 영향
김민종 ( M J Kim ),김관영 ( K Y Kim ),어광준 ( G J Euh ),임영목 ( Y M Rhym ),이기안 ( K A Lee ) 대한금속재료학회(구 대한금속학회) 2015 대한금속·재료학회지 Vol.53 No.3
A7003 alloy underwent T5 and T6 heat treatments (T5: 90 ℃ for 5 hrs and 150 ℃ for 16 hrs; T6: 470 ℃ for 3 hrs followed by artificial aging at 80 ℃ for 14 hrs, and 120 ℃ for 42 hrs); the tensile and fatigue properties of the treated materials were then examined. High-cycle fatigue tests were conducted at R (stress ratio)=0.1, and f (frequency)=20 Hz. The average grain size of A7003-T5 alloy was 3.8 μm, and that of A7003-T6 alloy was 4.1 μm. Both of the alloys were found to have MgZn2 (?), Fe-based intermetallic phases in their aluminum matrix. A7003-T6 alloy had finer MgZn2 (?) phases distributed more evenly than A7003-T5 alloy. Tensile test results showed that A7003-T6 alloy had higher strength (Y.S. & T.S.) and lower elongation compared to those of A7003-T5 alloy. High cycle fatigue results showed that A7003-T6 alloy had longer fatigue limit (320 MPa) than that (290 MPa) of T5 alloy. A7003-T6 alloy was found to perform better in all other fatigue stress conditions, too. Based on the observation of tensile and fatigue fracture surfaces, the correlations between microstructures made by heat treatments and mechanical/fatigue properties were also investigated along with the fatigue deformation mechanism of A7003 alloy.(Received April 22, 2014)
Eco ADC12(Al-Si-Cu) 합금의 인장 및 고주기 피로 변형 거동
김관영(G. Y. Kim),김규식(K. S. Kim),김세광(S. K. Kim),윤영옥(Y. O. Yoon),이기안(K. A. Lee) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.5
The effects of Eco-Mg addition (0.6% and 0.8% wt%) on the microstructure development and tensile, high cycle fatigue properties of Eco-ADC 12 alloys have been investigated. Eco-ADC 12 alloys is made using Eco-Mg(Mg-Al₂Cu) in place of element Mg during the manufacture of alloy ADC 12. Microstructure analysis, tensile test, high cycle fatigue test were conducted in this study. The alloy consisted of α-Al, eutectic Si and Al₂Cu phase whit higher pore fraction. The tensile and high cycle fatigue results indicated that the fatigue strength of the Eco-ADC 12(0.8%) alloy was higher than those of the Eco-ADC12(0.6%) alloy. This study also attempted to clarify the micro-mechanism of fatigue deformation behavior related with its microstructure.
Modified 2024 알루미늄 합금의 인장 및 피로 연구
김관영(G. Y. Kim),김선호(S. H. Kim),윤영옥(Y. O. Yoon),김세광(S. K. Kim),조규상(K. S. Cho),이기안(K. A. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
In this study, the microstructures and mechanical properties of the recently developed Eco-2024-T3 alloy were examined. Eco2024 is made using Eco-Mg(Mg-Al₂Ca)in place of element Mg during the manufacture of alloy 2024-T3. This is an alloy that has economic advantage and excellent properties. Alloy Eco2024 showed smaller crystal grains that were distributed more evenly compared to the existing alloy 2024-T3. It consisted of Al matrices containing minute amounts of Al₂CuMg, Al₂Cu and Ca phases and showed microstructures with reduced amounts of Fe phases or oxide. As a result of tensile test, this alloy exhibited yield strength of 413MPA, tensile strength 527㎫, and elongation of 15.4%. In other words, it showed higher strength than the existing alloy 2024 but was similar to the existing alloy 2024 in terms of elongation. In fatigue tests, alloy Eco2024-T3 recorded fatigue limit of 330 ㎫ around 80% of its yield strength this is a much more excellent property compared to the existing alloy 2024-T3, which has fatigue limit of 250㎫. Based on the aforementioned results, the correlation between the excellent mechanical properties of alloy Eco2024-T3 and its microstructure was examined.
Modified 7050-T7451 알루미늄 합금의 고주기 피로 변형 거동에 미치는 Ca첨가의 영향
김관영(G. Y. Kim),김규식(K. S. Kim),김세광(S. K. Kim),조규상(K. S. Cho),이기안(K. A. Lee) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.5
This study examined the microstructures and mechanical and fatigue properties of the recently developed Eco7050-T7451 alloy. Eco7050-T7451 is made using Eco-Mg(Mg-Al₂Ca) in place of the element Mg during the manufacture of alloy 7050-T7451, having economically advantageous and superior properties. In the microstructure observation, average grain size was measured to be 5.2㎛. It consisted of Al matrix containing minute amounts of Al₂CuMg, MgZn₂, And Ca phases and showed microstructure with reduced amounts of Fe phases or oxides. Tensile test exhibited that this alloy had yield strength of 509 MPa, Tensile strength of 559 MPa, elongation of 13.8 %, which showed greater strength than conventional alloy 7050 but the same elongation. Fatigue properties were significantly improved compared to those of conventional alloy (fatigue limit of 350MPa). The superior tensile and fatigue properties of Modified 7050-T7451 alloy were mainly attributed to grain size refinement, homogeneous distribution of 2<SUP>nd</SUP> phases, and reduced oxides.
저온 플라즈마를 이용한 디젤엔진 soot 제거에 관한 연구
채재우(J.O.Chae),황재원(J.W.Whang),김관영(K.Y.Kim),이창신(C.S.Lee),선희석(H.S.Sun),김건우(G.O.Kim) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_1
The importance of the elimination of air-pollution caused by the increase of energy demands is requested seriously in these days. Especially, the diesel engine exhaust gas is very harmful and difficult to reduce with current methods. The exhaust gas treatment technology using non-thermal plasma is one of the advanced method, and has advantage of high removal efficiency with low energy consumption. In this study, the experiment is carried with 1 cylinder agricultural diesel engine, and it is shown the soot removal efficiency with various engine R.P.M. and different reactor types(square-shape electrode reactor, planar-type reactor, and mixed type reactor).<br/>