Effect of the Parameters in Inverted Cone-Shaped Pouring Channel Process on the Microstructure of Semi-Solid 7075 Aluminum Alloy Slurry

Abstract:

The semi-solid slurry of 7075 aluminum alloy was prepared by using an innovative non-stirring technology that can be called inverted cone-shaped pouring channel process (ICSPC). The effect of pouring temperature and structural parameters of the channel on the microstructure of semi-solid 7075 aluminum alloy slurry was investigated. The experimental results reveal that when keeping the pouring temperature within some range, the slurry with spherical primary α(Al) grains can be prepared by ICSPC process, and with the decline of the pouring temperature, the microstructure of semi-solid 7075 aluminum alloy is more desirable under the same channel. The appropriate combination of channel length and interior surface slope can also give rise to a transition of the growth morphology of primary α(Al) from coarse dendritic to coarse particle-like and further to fine-globular at the same pouring temperature. In ICSPC process, numerous effective heterogeneous nucleation takes place in the melt as it flowed along the interior surface of the channel and the morphology of primary α(Al) grains is virtually determined by the degree of contact condition between the superheat melt and the interior surface of the channel. A better contact condition stands for a stronger heat extraction from the melt, and will finally appear as a remarkable increase of primary α(Al) grains survived in the melt, which will conspicuously promote the spherical growth of the primary α(Al) grains.

• Periodical: Solid State Phenomena (Volumes 192-193)
• Pages: 415-421
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.192-193.415
• Online since: October 2012
• Authors: Bin Yang, W.M. Mao, Jian Nan Zeng, Xiao Jun Song
• Keywords: 7075 Al-Alloy, Inverted Cone-Shaped Pouring Channel, Primary α-Al Grain, Semi-Solid

References

[1] M.C. Flemings, Behavior of metal alloys in the semi-solid state, J. Metall Trans A. 22 (1991) 957-981.

[2] Z. Fan, Semisolid metal processing, J. International Materials Reviews. 47 (2002) 1-37.

[3] J. Wannasin, S. Thanabumrungkul, Development of a semi-solid metal processing technique for aluminium casting applications, J. Songklanakarin Journal of Science and Technology. 30 (2008) 215-220.

[4] P. Kapranos, Semi-solid metal processing-A process looking for a market, J. Solid State Phenomena. 141 (2008) 1-8.

DOI: 10.4028/www.scientific.net/ssp.141-143.1

[5] R.A. Martinez, M.C. Flemings, Evolution of particle morphology in semisolid processing, J. Metall Trans. 36 (2005) 2205-2210.

DOI: 10.1007/s11661-005-0339-1

[6] J. Wannasin, R. Canyook, R. Burapa, M.C. Flemings, Evaluation of solid fraction in a rheocast aluminum die casting alloy by a rapid quenching method, J. Scripta Materialia. 59 (2008) 1091-1094.

DOI: 10.1016/j.scriptamat.2008.07.029

[7] S. Wu, L. Xie, J. Zhao, H. Nakae, Formation of non-dendritic microstructure of semi-solid aluminum alloy under vibration, J. Scripta Materialia. 58 (2008) 556-559.

DOI: 10.1016/j.scriptamat.2007.11.010

[8] W.M. Mao, A.M. Zhao, C.L. Cui, X.Y. Zhong, The formation mechanism of non-dentritic primary α(Al) phases in semi-solid AlSi7Mg alloy, J. Acta Metallugica Sinica. 35 (1999) 971-974.

[9] P. Wang, G.M. Lu, J.Z. Cui, Microstructure of nearby liquidus semi-continuous casting aluminum alloy A356, J. Acta Metallugica Sinica. 38 (2002) 389-392.

[10] H. Kaufmann, H. Wabusseg, P.J. Uggowitzer, Metallurgical and processing aspects of the NRC semi-solid casting technology, J. Aluminum. 76 (2000) 70-75.

[11] R.G. Guan, F.R. Cao, L.Q. Chen, Dynamical solidification behaviors and microstructural evolution during vibrating wavelike sloping plate process, J. J Mater Proc Technol. 209 (2009) 2592-2601.

DOI: 10.1016/j.jmatprotec.2008.06.007

[12] H. Mehrara, M.N. Ahmadabadi, S. Ashourid, J. Ghisinejad, Modeling of inclined cooling plate semisolid processing by model alloy, J. Diffusion and Defect Data Part B. 141 (2008) 785-790.

DOI: 10.4028/www.scientific.net/ssp.141-143.785

[13] T. Thaga, P. Kapranos, Simple rheocasting processes, J Mater Process Technol. 130 (2002) 594-598.

[14] A.J. Carr, D.J. Browne, M.J. Hussey, N. Lumsden, M. Scanlan. Modelling and experimental development of the direct thermal method of rheocasting, J. International Journal of Cast Metals Research. 20 (2007) 325-332.

DOI: 10.1179/136404608x286147