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이진경(J.K. Lee),이상필(S.P. Lee),이준현(J.H. Lee),손인수(I.S. Son),배동수(D.S. Bae) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
A carbon steel(A53) in this study is used as material of pipe in marine plant and ship industry. An weld to connect carbon steels is necessary and an effect of weld on properties of carbon steel has been completed by many researchers. In this study, dynamic behavior of welded carbon steel is studied by acoustic emission(AE) technique, one of nondestructive tests. There are lots of AE parameters to analyze the damage behavior of carbon steel by external loading. AE parameters of energy, cumulative count, amplitude and AE event were used, and each parameter was differentiated according to the damage degree of carbon steel. Energy showed high level at elastic range of load curve, while amplitude was the highest value at the hardening region. Cumulative count showed similar growth tendency with loading curve. In addition, ultrasonic technique and hardness test were applied to evaluate the mechanical properties according to the base zone, HAZ region and weld zone of the weld specimen. The velocity and attenuation ratio showed a little of change according to the each zones, and the evaluation of ultrasonic wave on the each zone of the specimen was an useful method to clarify the mechanical properties of the carbon steel.
이종섭(J. Lee),김용배(Y. B. Kim),이근안(G. A. Lee),김응주(E. Z. Kim),배동수(D. S .Bae),박준표(J. P. Park),이상목(S. Lee) 한국소성가공학회 2012 한국소성가공학회 학술대회 논문집 Vol.2012 No.10
In this study, Hydro Co-Extrusion Process of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duo-casting were investigated. Sleeve of the duo-casted billets is 3003 Al-Mn alloy and core is 4004 Al-Si alloy. It is expected hydrostatic stress during the HCE process enhances formability of materials and minimize any defects in extruded billets due to different material properties between two Al alloys. The duo-casted billet was extruded at temperature of 423K and with extrusion ratio of 5. The effect of the HCE on microstructure of the billet was investigated by an optical microscope.