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Al 7003 합금의 열처리(T5, T6)에 따른 인장 및 고주기 피로 변형 거동
김민종(M. J. Kim),김관영(K. Y. Kim),어광준(K. J. Euh),이기안(K. A. Lee) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.10
Tensile and high-cycle fatigue defomation behavior due to heat treatment (T5, T6) on Al 7003 alloy were investigated. Aluminum 7003 alloy was produced through casting and extruding, and then heat treatments of T5(90 ℃, 5hrs. + 150 ℃, 16hrs.) and T6 (470 ℃, 3hrs., 80 ℃ and WQ solution processing, 14hrs + 120 ℃, 42hrs.) followed respectively. Using the two kinds of Al 7003 alloys to which different heat treatments were applied, microstructure analysis, tensile tests, room-temperature high-cycle tests, etc., were performed. The observation of microstructure showed that the average grain size was 3.8 μm for T5 alloy and 4.1 μm for T6 alloy. Both kinds of heat-treated alloys were analyzed to be Al-matrix and to have MgZn₂ and Fe-intermetallic phase; MgZn₂ with T6 condition had finer and more regular distribution compared to the one with T5 condition. The tensile results showed the following properties under the T5 heat treatment condition: tensile strength of 359.0MPa; yield strength of 326.1MPa, and; ductility of 28.0%. On the other hand, under the T6 condition, tensile strength was 411.6MPa, yield strength was 373.6MPa, and ductility was 26.3%. In other words, under the T6 heat treatment condition, relatively higher strength and minor decrease in ductility were obtained compared to those under the T5 condition. The high-cycle fatigue results showed that the fatigue limit (10<SUP>7</SUP>cycle) under the T5 heat treatment condition was 290MPa, and the fatigue limit (10<SUP>7</SUP>cycle) under the T6 condition was 320WPa. Under all stress conditions, the fatigue life of T6 alloy was verified to be longer than that of T5 alloy. Based on the observation on tensile and fatigue fracture surfaces, the excellent properties of the T6 heat-treated alloy were confirmed to cone from the effective reinforcement phases with small and uniform distribution generated by the heat treatment under such condition. Based on these results, Al 7003 alloy`s tensile and fatigue deformation mechanisms were also discussed.
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 AM30 마그네슘 합금의 인장, 고주기 피로 및 피로 균열 전파 변형 거동
김민종(M. J. Kim),김세광(S. K. Kim),임현규(H. K. Lim),박중철(J. C. Pack),이기안(K. A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Tensile and fatigue deformation behaviors of newly developed ECO AM30 alloy was investigated. Microstructure analysis,tensile, high cycle fatigue, fatigue crack propagation tests were conducted. In the microstructure observation, average grain size was 5.8㎛ for AM30 alloy (conventional reference material) and 2.5 ㎛ for ECO AM30 alloy. ECO alloy consisted of Mg matrix containing minute amounts of Mg17Al12, Al6Mn, Mg32(Al, Zn)49, and Al₂Ca phases. Tensile results showed that the properties of ECO AM30 alloy (T.S: 313.8MPa, Y.S: 184.3MPa, elongation: 21.3%) were superior to those of AM30 alloy (T.S: 310.2MPa, Y.S: 177.3MPa, elongation: 16.5%). High cycle fatigue limit of AM30 (set at 10<SUP>7</SUP> cycles) was 130 MPa and that of ECO AM30 alloy was 170 MPa. Result of fatigue crack propagation experiment, both alloys showed similar fatigue crack propagation rate. Better tensile and fatigue properties of ECO AM30 alloy is mainly due to the refined grains and homogeneously distributed fine strengthening particles.
ECO AZ31 마그네슘 합금의 인장, 고주기 피로 및 피로 균열 전파 변형 거동
김민종(M. J. Kim),김관영(K. Y. Kim),김세광(S. K. Kim),임현규(H. K. Lim),박중철(J. C. Pack),이기안(K. A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
Tensile and fatigue deformation behaviors of newly developed ECO AZ31 alloy was investigated. Microstructure analysis, tensile, high cycle fatigue, fatigue crack propagation tests were conducted. In the microstructure observation, average grain size was 3.2㎛ for AZ31 alloy and 2.7㎛ for ECO AZ31 alloy. Alloys consisted of Mg matrix containing minute amounts of Mg17Al12, Al6Mn, Mg12(Al, Zn)49phases. Tensile results showed that the properties of ECO AZ31 alloy (T.S: 314.6MPa, Y.S: 188.7MPa, elongation: 20.2%) were superior to those of AZ31 alloy (T.S: 306.4MPa, Y.S: 177.6MPa, elongation: 17.7%). High cycle fatigue limit of AZ31 (set at 10<SUP>7</SUP> cycles) was 140MPa and that of ECO AZ31 alloy was 160MPa. Result of fatigue crack propagation experiment, both alloys showed similar fatigue crack propagation rate. The cause of better properties the new ECO alloy was also discussed based on the fractography observations.
Mg+Al<sub>2</sub>Ca 첨가 ADC12 (Al-Si-Cu) 합금의 미세조직, 인장 및 고주기 피로 특성
김영균,김민종,김세광,윤영옥,이기안,Kim, Y.K.,Kim, M.J.,Kim, Shae K.,Yoon, Y.O.,Lee, K.A. 한국소성가공학회 2017 소성가공 : 한국소성가공학회지 Vol.26 No.5
This study investigated the microstructure, tensile strength, and high cycle fatigue properties of ADC12 aluminum alloys with different $Mg+Al_2Ca$ contents manufactured using die casting process. Microstructural observation identified the presence of ${\alpha}-Al$, eutectic Si, $Al_2Cu$, and Fe-intermetallic phases. The increase of $Mg+Al_2Ca$ content resulted in finer pore size and decreased pore distribution. Room temperature tensile strength tests were conducted at strain rate of $1{\times}10^{-3}/sec$. For 0.6%Mg ADC12, measured UTS, YS, and El were 305.2MPa, 157.0MPa, and 2.7%, respectively. For 0.8%Mg ADC12, measured UTS, YS, and El were 311.2 MPa, 159.4 MPa, and 2.4%, respectively. Therefore, 0.8% ADC12 alloy had higher strength and slightly decreased elongation compared to 0.6% Mg ADC12. High cycle fatigue tests revealed that 0.6% Mg ADC12 alloy had a fatigue limit of 150 MPa while 0.8% Mg ADC12 had a fatigue limit of 160MPa. It was confirmed that $Mg+Al_2Ca$ added ADC12 alloy achieved finer, spherical eutectic Si particles, and $Al_2Cu$ phases with greater mechanical and fatigue properties since size and distribution of pores and shrinkage cavities decreased as $Mg+Al_2Ca$ content increased.
MIM(금속분말사출성형)공법으로 제작된 Fe-2%Ni합금의 미세조직 및 기계적 특성
조규상(K. S. Cho),김민종(M. J. Kim),김관영(K. Y. Kim),정재옥(J. O. Jeong),박시우(S. W. Park),이기안(K. A. Lee) 한국소성가공학회 2013 한국소성가공학회 학술대회 논문집 Vol.2013 No.5
Microstructure and mechanical properties of Fe-2%Ni alloy produced by MIM(Metal Injection Molding) were investigated. Microstructure analysis, tensile test, and high cycle fatigue test were conducted. In the microstructure observation results, non-regular grain and inhomogeneous ferrite and pearlite were appeared. Non-sintered C, Si, Mn including phases were also detected. As a result of tensile test, MIMed Fe-2%Ni alloy represented yield strength of 285,5 MPa, tensile strength 605.7 MPa, and elongation 6.02%. The tensile properties of MIMed Fe-2%Ni alloy showed higher elongation and similar strengths compared to those of conventional Fe-2%Ni alloy. High cycle fatigue limit was obtained as 440 MPa. Micro-mechanisms of tensile and fatigue deformation behaviors in MIMed Fe-2%Ni alloy were also discussed based on the fractography observation.
Modified Al-Si-Mg 계 조조용 합금의 ECO-Mg 함량 변화에 따른 인장 및 피로 변형 거동
함기수(G.S. Ham),백상우(S.W. Baek),김민종(M.J. Kim),김세광(S.K. Kim),윤영옥(Y.O. Yoon),조규상(K.S. Cho),이기안(K.A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
The effect of ECO-Mg addition on the microstructure, tensile and fatigue deformation behaviors of modified Al-Si-Mg casting alloy was investigated. Four different alloys having various amounts of ECO-Mg (0.3, 0.4, 1.0 and 1.5 wt.%) were prepared though sand casting process. OM microscopy, Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-ray Diffraction (XRD) analyses was examined as well as hardness, tensile, and fatigue tests. Modified aluminum alloy consisted of α-Aluminum (dendrite shape), eutectic Si, Mg₂Si and Fe-intermetallic phases. It was found that DAS(Dendrite Ann Spacing) gradually decreased and eutectic Si, Fe-intermetallic phases were more finely distributed in the matrix with increasing the amount of ECO-Mg. Tensile and fatigue properties were also improved with increasing ECO-Mg content. The micro-mechanisms of tensile and fatigue deformations of the alloy were also discussed based on the fractography observation results.