Microstructural Evolution of AZ31 Mg Wrought Alloy during Partial Remelting for Thixoextrusion

Abstract:

An attempt has been made to investigate feasibility of thixoextrusion for AZ31 Mg wrought alloy through simple partial remelting. Microstructural evolution of AZ31 Mg wrought alloy for thixoextrusion was investigated as functions of isothermal holding temperature and time in the partially remelted semisolid state. The interesting point of this study was that the thixotropic structures of AZ31 Mg wrought alloy without additional pretreatment could be obtained through simple partial remelting. The uniform average grain size and liquid fraction according to the isothermal holding time were very important for the thixoextrusion. Because, it is must be considered on actual extrusion time. The liquid fraction was increased with increasing isothermal holding temperature and time. But, the liquid fraction was almost uniform after 10 min. The average grain size was decreased with increasing isothermal holding temperature. On the other hand, as the holding time increased, the average grain sizes were uniform at 615
and 622
. This phenomenon is very useful for thixoextrusion in terms of process control such as actual extrusion time.

• Periodical: Solid State Phenomena (Volumes 116-117)
• Pages: 251-254
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.116-117.251
• Online since: October 2006
• Authors: Young Ok Yoon, Shae K. Kim
• Keywords: AZ31 Mg Wrought Alloy, Microstructural Evolution, Partial Remelting, Thixoextrusion

References

[1] E.F. Emley: Principles of Magnesium Technology (London: Pergamon Press, 1966).

[2] S. Kleiner, O. Beffort and P.J. Uggowitzer: Scripta Mater. Vol. 51 (2004), p.405.

[3] M.C. Fleming: Metall. Trans. AVol. 22 (1991), p.957.

[4] D.H. Kirkwood: Inter. Mater. Rev. Vol. 39 (1994), p.173.

[5] K.P. Young and R. Fitze: Proc. 3rd Int. Conf. on Semi-Solid Processing of Alloys and Composites (1994), p.155.

[6] J. F. Seconde and M. Suery : J. Master. Sci. Vol. 19 (1984), p.3995.

[7] S. Annavarapu and R.D. Doherty: Acta. Mater. Vol. 43 (1995), p.3207.