镁合金正挤压-扭转变形的数值模拟与实验研究

Numerical simulation and experimental research of AZ31 Mg alloys processed by direct extrusion and torsional deformation

结合传统挤压与扭转变形的特点提出正挤压-扭转复合变形方式,采用有限元软件对其变形方式进行数值模拟。研究扭转角度对坯料变形过程中累积应变的影响,并对经过不同扭转角度变形后坯料的等效应变分布的不均匀程度进行定量分析。根据正挤压-扭转复合变形的模拟结果,设计出较优的模具结构并进行实验研究。结果表明:正挤压-扭转复合变形可以显著提高镁合金变形过程的累积应变,随着扭转角度的增大,累积应变增大,但不均匀程度相对增加,最大等效应变高达3.75。当模具扭转角为40°时,试样可获得较大的等效应变和均匀的等效应变分布。在复合变形后,AZ31镁合金的晶粒尺寸由300μm显著细化至约6μm。

Combining the feature of traditional extrusion and torsional deformation, direct extrusion and torsional compound deformation was proposed, and numerical simulation of deformation process was investigated using finite element software. Effect of torsion angle on cumulative strain during the deformation process was studied, and the non-uniformity of the equivalent strain distribution after different torsion angle deformation was also analyzed quantitatively. According to the simulation results of direct extrusion and torsional deformation, reasonable die structure was designed, and experimental research was carded out. The results show that the direct extrusion and torsional compound deformation can significantly enhance the accumulation strain of deformed magnesium alloys, and the cumulative strain increases with the increase of torsional angle, the maximum equivalent strain can get up to 3.75, but the degree of nonuniformity increases relatively. The specimen can obtain larger and more uniform distribution of equivalent strain for torsion angle of 40°. After compound deformation, the grain size of AZ31 magnesium alloy can be significantly refined from 300μm to about 6μm.