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The Mg-3 pct Al-1 pct Zn (AZ31) alloy has been used as a model material for understanding the grain-refinement process of a Mg alloy fabricated by equal-channel angular extrusion (ECAE). The effects of ECAE processing parameters on grain refinement have also been studied; it was found that these effects are quite different from those for fcc metals. A multitemperature extrusion procedure has been developed, which can produce an ultrafine-grained AZ31 alloy having a grain size 0.37 lm. For the AZ31 alloy, this ultrafine-grained alloy has a record high strength accompanied by reasonably good tensile ductility. The success of the development of this ECAE procedure proves that ECAE can offer a good opportunity for the development of high-strength Mg alloys.

The present study examines the microstructure and tensile behaviour of twinning induced plasticity steel with different Mn contents. The results show that reducing the Mn content from 24 to 15 wt-% is beneficial for the improvement of the tensile strength and fracture strain of the steels. The effect of Mn content on the microstructure and workhardening behaviour as well as the effect of strain rate on the microstructure and tensile behaviour is discussed.

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