Dynamic Recrystallization Behavior And Simulation Of GWZK134 Alloy During Hot Deformation

Rare earth magnesium alloys have high strength,excellent heat resistance,corrosion resistance and creep resistance,and have become a research and development hotspot in aerospace,military and other high-tech fields.As a necessary raw material for forming large-scale extrusion parts,large-size RE-Mg alloy ingots are widely used in missile shell,weapon armor and automobile hub.In this paper,the experimental study of large-size GWZK134 alloy ingot is carried out.The rheological stress characteristics and the evolution law of microstructure are analyzed.The dynamic recrystallization behavior during hot compression is predicted by finite element simulation technology,and the visualization of the variation law of characterization parameters is realized.The developed coupling system of physical experiment-constitutive-dynamic recrystallization phenomenological-finite element simulation has important guiding significance for the optimization of forming process,the control of grain size and the improvement of properties of extruded parts.The rheological stress curves of GWZK134 alloy were obtained by thermal simulation compression experiments at strain rates of 0.001s^-1,0.01s^-1,0.1s^-1 and 1s^-1,temperatures of360?,400?,440?,480?and maximum compression of 60%.With the increase of strain,the flow stress curve shows obvious dynamic recrystallization characteristics.The decrease of strain rate and the increase of temperature will lead to the decrease of flow stress and peak strain.Based on the experimental data of thermal compression,the Arrhenius constitutive equation describing the variation of peak stress and the Fields-Backofen softening factor constitutive model describing the flow stress during the dynamic softening stage are constructed.Comparing the constitutive model value with the experimental value,the agreement is good.The dynamic recrystallization phenomenological model was constructed by linear fitting method.The parameters of the model were embedded in Deform-3D grain module.The finite element simulation platform of GWZK134 alloy was established.The hot compression process of the alloy was simulated numerically and the microstructure was observed with EBSD analysis technology.It is found that the distribution of equivalent strain in the alloy is inhomogeneous,and the dynamic recrystallization integral corresponds to the distribution of equivalent strain.With the increase of deformation,the rise of deformation temperature and the decrease of strain rate,the level of dynamic recrystallization increases and the integral number of dynamic recrystallization increases.In addition,without considering the effect of strain on grain size,the increase of deformation temperature and the decrease of strain rate will lead to the increase of dynamic recrystallization grain size and the decrease of overall average grain size.