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Abstract:The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 °C, 350 °C and 450 °C have been studied in compression. The extruded material had a fiber texture with > < 0 1 10 parallel to the extrusion axis. When extruded at 450 °C, the texture was less intense and the > < 0 1 10 direction moved away from the extrusion axis. The processing maps for the material extruded at 300 °C and 350 °C are qualitatively similar to the material with near-random texture (cast-homogenized) and exhibited three dynamic recrystallization (DRX) domains. In domains #1 and #2, prismatic slip is the dominant process and DRX is controlled by lattice self-diffusion and grain boundary self-diffusion, respectively. In domain #3, pyramidal slip occurs extensively and DRX is controlled by cross-slip on pyramidal slip systems. The material extruded at 450 °C exhibited two domains similar to #1 and #2 above, which moved to higher temperatures, but domain #3 is absent. The results are interpreted in terms of the changes in > < 0 1 10 fiber texture with extrusion temperature. Highly intense > < 0 1 10 texture, as in the rod extruded at 350 °C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 °C (domain #3).

Magnesium alloys gain a growing interest from transportation industry due to their high potential for lightweight applications. The driving forces for magnesium use is the requirement given by legislation to reduce the emission of green house gases and to apply materials that can be recycled. [1] Magnesium alloys possess several beneficial features as good machinability, processability via different casting routes and regarding their specific property profile they can compete with aluminium alloys and even steel. While the corrosion behavior of Mg-based materials is a problem that can be controlled satisfactorily by the use of high purity alloys in the combination with surface coatings and appropriate design rules, the limited deformability of hexagonal closepacked magnesium structure remains problematic. In fact, magnesium alloys have not really been introduced to the deformation processes, because they can be deformed satisfactorily only at temperatures above 250°C and at the slow deformation rates. These limitations increase the price of the material and hinder their broader use.AZ31 is one of the most commonly used magnesium alloy suitable for the hot deformation processes such as extrusion, forging or rolling. It is well known that thermomechanically deformed alloys possess several advantages over their cast counterparts. Cast structures are often inhomogeneous exhibiting large grains that significantly reduce workability of the material -large grain boundaries allow easy crack initiation and propagation. Thus, to improve the microstructural properties, thermal treatments are often performed before and after deformation. In addition, cast structures intrinsically contain inhomogeneously distributed alloying elements, which may segregate and hence the temperature range and deformation rate, over which the cast structure can be processed, is rather limited and must be carefully selected. Therefore, it is necessary to define an optimal processing window with regard to obtaining a high quality final product.The capability of the material to be processed under plastic deformation without fracturing is known as workability. Workability is a material property that can be influenced by several factors as initial microstructure, temperature and strain rate applied, strain and moreover by stress state in the deformation zone.In recent years, the technique of processing maps based on the Dynamic Material Model (DMM) was found to be beneficial for optimizing the hot workability and controlling the structural development during processing. [2][3][4][5] The processing maps demonstrate the optimum parameters for designing the metalworking processes without a need for often complicated, expensive and time-consuming 'trial and error' methods. A major database of processing maps has been developed for a variety of materials and has been published by Prasad and Sasidhara. [6] The processing maps are constructed by superimposition of two independent maps. The first -a power dissipation map -represents in a frame of temperatures...