Preparation of Globular Microstructure Aluminum Alloy Using Cooling Slope Casting as Feed Material for Equal Channel Pressing Process

Abstract:

Equal channel angular pressing (ECAP) could be used to achieve ultra fine grains in bulk aluminum alloy through severe plastic deformation. Typically a feed material of as-cast aluminum alloys is used with a typical hypoeutectic solidification structure, consisting of primary aluminum dendrites and interdendritic network of lamellar eutectic silicon. On the other hand, semi-solid metal casting provides non-dendritic and globular microstructure which is one of a considerable factor in obtaining homogenous microstructure after ECAP. This work is an attempt to produce aluminum alloy with globular microstructure using cooling slope semi-solid casting process which is believed suitable as a feedstock for ECAP. The aim of this work described in this paper was to understand of microstructural evolution of aluminum structure during cooling slope casting process. Two experiments were carried out. A sample was casted via a cooling slope into a vertical cold mild steel mould at pouring temperature of 640°C. Cooling slope length of 250 mm, slope temperature of room temperature and tilt angle of 60^o was applied. Another sample was casted directly into a vertical cold mild steel mould at pouring temperature of 640°C. The primary α-Al phases in the sample that casted without cooling slope was mostly in dendritic throughout the section of sample whilst the primary α-Al phases transformed completely into non-dendritic in the sample that was casted via the cooling slope. Therefore, the transformation is believed resulted from the effect of cooling slope

• Periodical: Advanced Materials Research (Volume 1024)
• Pages: 247-250
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.1024.247
• Online since: August 2014
• Authors: Nguyen Van Thuong, Zuhailawati Hussain*, Anasyida Abu Seman, T.D. Huy
• Keywords: Aluminium Alloy, Cooling Slope, Globular Microstructure

References

[1] Segal, V. M. 1995. Materials processing by simple shear. Materials Science and Engineering: A, 197, 157-164.

[2] Segal, V. M. 1999. Equal channel angular extrusion: from macromechanics to structure formation. Materials Science and Engineering: A, 271, 322-333.

DOI: 10.1016/s0921-5093(99)00248-8

[3] Segal, V. M. 2004. Engineering and commercialization of equal channel angular extrusion (ECAE). Materials Science and Engineering: A, 386, 269-276.

DOI: 10.1016/s0921-5093(04)00934-7

[4] Spencer, D., Mehrabian, R. & Flemings, M. 1972. Rheological behavior of Sn-15 pct Pb in the crystallization range. Metallurgical Transactions, 3, 1925-(1932).

DOI: 10.1007/bf02642580

[5] T. Motegi, Ogawa, N., Kondo, K., Liu, C. & Aoyama, S. 1998. Continuos casting of semisolid Al-Si-Mg Alloy. in: T. Sato (Ed. ), Proceedings of ICAA6, Toyohashi, pp.297-302.

[6] Bower, T. & Flemings, M. 1967. Formation of the chill zone in ingot solidification. AIME MET SOC TRANS, 239, 216-219.

[7] Motegi, T., Tanabe, F. & Sugiura, E. Continuous casting of semisolid aluminium alloys. Materials Science Forum, 2002. Trans Tech Publ, 203-208.

DOI: 10.4028/www.scientific.net/msf.396-402.203

[8] Mondolfo, L. F. 1976. Aluminum Alloys: Structure and properties, London; Boston, Butterworth & Co Ltd.

[9] Kurz W & Fisher 1989. Fundermentals of Solidification, Switzerland - Germany - UK - USA, Trans. tech. publication.

[10] Flemings, M. C. 1974. Solidification processing. Metallurgical Transactions, 5, 2121-2134.

[11] Flemings, M. 1991. Behavior of metal alloys in the semisolid state. Metallurgical Transactions B, 22, 269-293.

DOI: 10.1007/bf02651227