Analysis of hot deformation behavior and processing map of extruded AZ40 alloy

The Gleeble-3500 thermal simulation tester was used to perform hot deformation behavior on the extruded AZ40 Mg alloy to analyze the trend of the true stress-strain curve after compression and to obtain the influence of the flow stress on the deformation temperature and strain rate. Subsequently, the constitutive equation was constructed for extruded AZ40 alloy based on the hyperbolic-sine relationship, and the thermal processing map of extruded AZ40 alloy was established based on the dynamic material model (DMM), thereby estimating the processing range of extruded AZ40 alloy. The results show that the rheological curve of extruded AZ40 alloy is characterized by obvious dynamic recrystallization. Furthermore, during the compression process, the peak stress of extruded AZ40 alloy decreases with the increase of deformation temperature, while increases with the increase of strain rate. Moreover, the proportion of dynamic recrystallized grains (DRGs) decreases with the increase of the strain rate under the same deformation temperature condition; while the DRGs size increases with the increase of the deformation temperature under the same strain rate condition. The coarse uncrystallized grains show obvious crystallographic orientations of 〈10<span style="border-top: 1px solid; padding-top: 0px;">1</span>0〉‖ND and 〈2<span style="border-top: 1px solid; padding-top: 0px;">1</span><span style="border-top: 1px solid; padding-top: 0px;">1</span>0〉‖ND, while crystallographic orientation of DRGs is random distributed. Finally, through thermal processing map and tissue analysis, the optimal processing window was identified as <i>T</i>=573 K, $\dot \varepsilon $=0.1 s^-1.