目的采用新型复合大塑性变形技术正挤压-等径角挤压工艺(FE-ECAP),研究5052铝合金在室温条件下的变形行为。方法基于有限元分析软件DEFORM-3D,在FE-ECAP工艺下对5052铝合金进行有限元模拟,研究变形过程中挤压载荷、等效应变、金属流动速度等场量的分布规律。结果 5052铝合金在FE-ECAP变形过程中,挤压载荷曲线呈双峰形态分布,在挤压模口附近达到第一次峰值,第二次出现在转角处,挤压载荷值为347 k N,同时也是整个挤压过程的最大值;经过FE-ECAP变形后,等效应变大量累积,使得主要变形区达到了高度均匀的变形状态;坯料外转角处金属的流动速度值大于内转角处的流动速度值。结论根据以上结果分析,在FE-ECAP工艺下,为使变形坯料性能优越,应尽量提高坯料变形的均匀性。
In comparison with the conventional equal channel angular pressing（ECAP） process,a comprehensive study of influence of twist extrusion（TE） process on consolidating pure aluminum powder in tubes（PITs） by equal channel angular pressing and torsion（ECAPT） was conducted via three-dimensional（3D） finite element simulation,experimental investigation and theoretical analysis.Simulation results revealed that during the consolidation of aluminum powder particles by ECAPT,TE process played a significant role of back pressure.Due to the torsional shear and high hydrostatic pressure exerted by twist channel,both the magnitude and homogeneity of the effective strain were increased markedly.After one pass of ECAPT process using a square channel with an inner angle of 90° and a twist slope angle of 36.5° at 200℃,commercial pure aluminum powder particles were successfully consolidated to nearly full density.Simulation and experimental results showed good agreement.In the microstructure observations,grains were greatly refined.At the same time,porosities were effectively eliminated by shrinking in size and breaking into small ones.Microhardness test indicated that strain distribution of ECAPT-processed billet was more homogeneous with respect to the ECAP-processed one.All these improvements may be attributed to the extreme intense shear strain induced during ECAPT and the increase in self-diffusion coefficient of aluminum due to the back pressure exerted by TE process.
