Making Non-Dendritic Structure via Modified Cooling Slope Technique

Abstract:

The cooling slope technique has been developed in recent years, which controls the nucleation and growth of the primary grains during solidification to achieve fine and non-dendritic microstructures. In this study, A356 Al alloys were processed through a modified cooling slope technique to obtain fine, non-dendritic microstructures, in which the cooling rate of the cast crucible was controlled. Three process parameters, namely pouring temperature, inclined slope angle, and the cooling rate of the cast crucible, were varied during the processing. The cooling slope was water-cooled with a constant water flow rate. The solid fraction and the size distributions of the primary grains along the vertical and horizontal positions of the cast ingots were measured individually. The macro-segregation was examined in terms of the distribution of the solid fraction. The yields of the ingots were calculated for studying the efficiency of the cooling slope technique. The effects of the three process parameters on the microstructures, macro-segregation, and yields were studied by the Taguchi method.

• Periodical: Advanced Materials Research (Volumes 915-916)
• Pages: 602-607
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.915-916.602
• Online since: April 2014
• Authors: Y.T. Chen, Chi Tsao*, C.H. Chiang
• Keywords: A356 Aluminum Alloy, Modified Cooling Slope, Non-Dendritic Structure, Semi-Solid Processing

References

[1] D.B. Spencer, R. Mehrabian, M.C. Flemings: Metall. Trans. 3 (1972), p.1925–(1932).

[2] S. Nafisi, O. Lashkari, R. Ghomashchi, F. Ajersch, A. Charette: Volume 54, Issue 13 (2006), p.3503–3511.

DOI: 10.1016/j.actamat.2006.03.016

[3] E. Cardoso, H. V Atkinson and H. Jones: Microstructural evolution of A356 during NRC processing (8th Int. SSP. Conf. Limassol, Cyprus, 21-23 September 2004, published by TMS).

[4] A. Mitsuru, S. Hiroto, H. Yasunori, S. Tatsuo, S. Satoru, Y. Atsushi: Method and Apparatus for Shaping Semisolid Metals (UBE Patent EP0745694 A1, 1996).

[5] D.J. Browne, M.J. Hussey, A.J. Carr and D. Brabazon: Direct Thermal Method: new Process for Development of Globular Alloy Microstructure (Int. Journal of Cast Metals Research, 16, No. 3, 2003, pp.1-9).

DOI: 10.1080/13640461.2003.11819618

[6] Toshio Haga, P. Kapranos: Simple rheocasting processes (Journal of Materials Processing Technology 130–131 (2002), p.594–598).

DOI: 10.1016/s0924-0136(02)00819-1

[7] P. J. Uggowitzer, H. Kaufmann: Evolution of Globular Microstructure in New Rheocasting and Super Rheocasting Semi-Solid Slurries. (steel research int. 75 (2004) No. 8/9, pp.525-530).

DOI: 10.1002/srin.200405806