자동차용 Al-6Si-2Cu 합금의 용체화처리에 따른 미세조직 및 기계적 특성 변화

홍승표; 김정석; Seung-Pyo Hong; Chung-Seok Kim

Korean Journal of Materials Research, Vol.24, No.10, 538-542, October, 2014

DOI10.3740/MRSK.2014.24.10.538 Export Citation

자동차용 Al-6Si-2Cu 합금의 용체화처리에 따른 미세조직 및 기계적 특성 변화

Microstructure and Mechanical Properties on Solid Solution Heat Treatment of Al-6Si-2Cu Alloy for Lightweight Automotive

홍승표, 김정석^†

조선대학교 재료공학과

Seung-Pyo Hong, and Chung-Seok Kim^†

Department of Materials Science and Engineering, Chosun University, Gwangju 501-759, Korea

E-mail:

Microstructural and mechanical characteristics of Al-6Si-2Cu alloy for lightweight automotive parts were investigated. The test specimens were prepared by gravity casting process. Solution heat treatments were applied to as-cast alloys to improve mechanical properties. The microstructure of the gravity casting specimen presents a typical dendrite structure, having a secondary dendrite arm spacing (SDAS) of 37 μm. In addition to the Al matrix, a large amount of coarsened eutectic Si, Al2Cu intermetallic phase, and Fe-rich phases were identified. After solution heat treatment, single-step solution heat treatments were found to considerably improve the spheroidization of the eutectic Si phase. Two-step solution treatments gave rise to a much improved spheroidization. The mechanical properties of the two-step solution heat treated alloy have been shown to lead to higher values of properties such as tensile strength and microhardness. Consequentially, the microstructural and mechanical characteristics of Al alloy have been successfully characterized and are available for use with other basic data for the development of lightweight automotive parts.

Keywords:Al-Si-Cu alloy;solution heat treatment;spheroidization;lightweight automotive

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[1] Al-Alawi BM, Bradley TH, Appl. Energy, 113, 1323 (2014)

[2] Kim KT, J. Korea Foundry Soc., 31, 101 (2011)

[3] Sasaki K, Takahashi T, Int. J. Fatigue., 28(3), 203 (2006)

[4] Ceschini L, Morri A, Pivetti G, Mater. Design, 32, 1367 (2011)

[5] Zeren M, Karakulak E, Gumus S, Trans. Nonferrous. Met. Soc. China, 21, 1698 (2011)

[6] Samuel EH, Samuel AM, Doty HW, AFS. Trans., 30, 839 (1996)

[7] Li Z, Samuel AM, Samuel FH, Ravindran C, Valtierra S, J. Mater. Sci., 116, 1203 (2003)

[8] Ceschini L, Boromei I, Morri A, Seifeddine S, Svensso IL, Mater. Design, 36, 522 (2012)

[9] Sjolander E, Seifeddine S, Mater. Design., 31, 44 (2010)

[10] Nishimura T, Toda H, Kobayashi M, Kobayashi T, Uesugi K, Suzuki Y, J. Cast Metal. Res., 21, 114 (2008)

[11] Li YJ, Brusethaug S, Olsen A, Scripta. Mater., 54, 99 (2006)

[12] Luna IA, Molinar HM, Roman MJC, Bocardo JCE, Trejo MH, Mater. Sci. Eng. A., 561, 1 (2013)

[13] Ceschini L, Boromei I, Morri A, Seifeddine S, Svensson IL, J. Mater. Process. Tech., 209, 5669 (2009)