http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
김규식(K. S. Kim),이영재(Y. J. Lee),성시영(S. Y. Sung),한범석(B. S. Han),박중철(J. C. Park),이기안(K. A. Lee) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Fatigue deformation behavior of new heat resistant A1 alloy was studied at elevated temperature. The results of phase analysis showed that this alloy has basic A1 matrix, small amount of eutectic Si and Mg2Si phase, particulates with of (Co, Ni)3Al4 strengthening phase. High temperature tensile tests were conducted to identify the mechanical properties. From room temperature to 250℃, yield and tensile strengths of new heat resistant aluminum alloy didn"t show significant decrease and elongations increased slightly. High cycle fatigue tests were performed with R= 0,30 Hz at 130℃ and low cycle fatigue tests with strain rate of 2×10<SUP>-3</SUP> s<SUP>-1</SUP> at 250℃ respectively. Fatigue limit of high cycle fatigue of this alloy was 120 MPa at the 10<SUP>7</SUP> cycles. At plastic strain amplitude of 0.12%, a fatigue limit was got at 10<SUP>3</SUP> cycles with low cycle fatigue regime. These values were superior than those of conventional heat resistant aluminum alloy such as A319. Results of fractographical observation showed that second phases, especially (Co, Ni)3Al4 particles, affected to fatigue behavior. It is also attempted to clarify the mechanism of fatigue deformation of new resistant aluminum alloy related with its microstructure.
Al - Mg - Si - (Co, Ni) 알루미늄 합금의 고온 저주기 피로 변형 거동
김규식(K. S. Kim),성시영(S. Y. Sung),한범석(B. S. Han),박중철(J. C. Park),이기안(K. A. Lee) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
High temperature low cycle fatigue tests of new heat resistant aluminum alloy were conducted in this study. Al-Mg-Si-(Co, Ni) aluminum alloy consists of Al matrix, small amount of Mg2Si and (Co, Ni)3Al4 strengthening particles. Low cycle fatigue tests controlled by total strain were performed with strain ratio (R)=-1, strain rate=2x10<SUP>-3</SUP>s<SUP>-1</SUP> at 250℃. Fatigue limit of low cycle fatigue of this alloy showed plastic strain amplitue(Δεps) of 0.22% at the 10<SUP>3</SUP> cycles. This value was superior that that of conventional aluminum alloy such as A319. Results of fractographical observation showed that second phases, especially (Co, Ni)3Al4 particles, could act a strengthening role for low cycle fatigue behavior. It is also attempted to clarify the mechanism of high temperature low cycle fatigue behavior of Al-Mg-Si-(Co, Ni) alloy related with its micorstructure and energy dissipation anaysis.
압출재 6061 알루미늄 합금의 피로특성에 미치는 열처리의 영향
김선호(S. H. Kim),김규식(K. S Kim),어광준(K. J. Euh),조규상(K. S. Cho),이기안(K. A. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.5
The effect of heat treatment on the high-cycle fatigue behavior of 6061 extruded alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both AI-Si-Mg extruded (F) and heat treated (T6) conditions. From the tensile tests, yield and tensile strengths increased and elongation decreased by T6 heat treatment. The high-cycle fatigue results indicated that the fatigue strength of the 6061-T6 alloy was significantly higher than that of the 6061-F alloys. Fatigue cracks were initiated near the surface of specimens regardless of heat treatment. In the case of6061-T6 alloy, 2<SUP>nd</SUP> cracks easily appeared when the fatigue crack met Mg₂Si phase during fatigue propagation. Fine Mg₂Si phases could be formed and homogeneously distributed by T6 heat treatment. The Mg₂Si was believed to act an effective role of retardation of fatigue crack initiation and propagation. The fatigue deformation mechanism of extruded 6061 aluminum alloy was also discussed.
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.
스폿용접기의 용접품질 향상을 위한 동저항 데이터 베이스 구축
조승진(S.J.CHO),김재문(J.M.KIM),원충연(C.Y.WON),최규하(K.H.CHOI),김규식(K.S.KIM),목형수(H.S.MOK) 전력전자학회 1998 전력전자학술대회 논문집 Vol.- No.-
A dynamic electrical parameter monitoring device was designed to simultaneously record the instantaneous value of voltage, current, power. and resistance during spot welding. The data obtained using this technique have been analyzed in tern of the relationship of theses parameters to the phenomena occuring during the formation(surface break-down, nugget formation and mechanical collapse) of spot weld. Finally ,a database implementation is undertaken to develop techniques for improving weld quality of the resistance spot welder.<br/> <br/>