Coordinated control of preferred orientation and uniformity of AZ31 in accumulative alternating back extrusion

This paper discusses how the accumulative alternating back extrusion (AABE) process was improved by the addition of water-quench and preheating steps to mitigate the of temperature-drop problem caused by long process flows and the problem of die gap feeding. The effect of the number of extrusion cycles on grain refinement was further investigated to elucidate and rationalize the preferred orientation in AABE. Compression experiments were carried out in tandem to explore the effect of AABE on the mechanical properties of the materials. After eight cycles of AABE, the average grain size reached 5.58 mu m, and the fine-grain size reached <1 mu m. Microstructure results showed that the grain size was significantly refined via discontinuous dynamic recrystallization (DDRX) and uniformity increased with subsequent extrusion cycles. Analysis of the deformation behavior of AABE showed that there was a preferred orientation in the microstructure after alternating, and the orientation of the basal plane was related to the flow velocity field that was simulated by the finite element method. A high Schmid factor and high deformation uniformity was observed after alternating, which was favorable for subsequent processing. Increasing the number of extrusion cycles decreased the material strength and plasticity up to a certain point. Subsequently, an increase was observed, with eight cycles giving the most strength and plasticity. Moreover, the grain size and crystal orientation affected the mechanical properties of the structure. These results provide an important experimental basis for creating AABE methods and fine-tuning the microstructure properties in magnesium alloy.

Automated summary

This paper discusses improvements to the AABE process, including water-quench and preheating steps to address temperature-drop issues and die gap feeding, as well as the investigation of the effects of extrusion cycles on grain refinement and crystal orientation. The study also explores the mechanical properties of materials through compression experiments and shows that increasing extrusion cycles can refine grain size and improve mechanical properties. Additionally, the deformation behavior of AABE and its impact on material strength and plasticity were analyzed, providing insights into microstructure properties in magnesium alloy.