模具外角对等通道转角挤压纯铝变形过程的影响

模具外角对等通道转角挤压(ECAE)变形过程影响较大,文章利用有限元软件(MSC.Marc)模拟研究了模具外角对ECAE过程中等效应变、变形机理的影响。模拟结果表明,模具外角Ψ>0°～30°的范围内,等效应变的分布较为均匀;当模具外角Ψ>30°时,等效应变的分布越来越不均匀;当模具外角Ψ=0°～90°范围内逐渐增大时,试样的变形机理由单一剪切变形逐渐变为剪切变形与弯曲变形相结合的复合变形行为。为了验证模拟结果,对大尺寸纯铝进行了等通道转角挤压实验(模具内角Ф=90°,模具外角Ψ=30°),纯铝实验应变值的分布与大小和模拟应变值的分布与大小近似吻合。由光学显微组织可知,经ECAE挤压一次后,变形试样组织较为均匀,晶粒得到一定程度细化。

The influence of die outer corner angle on equal channel angular extrusion process

Equal channel angular extrusion(ECAE) process is greatly affected by die outer corner angle.In this paper,a finite element analysis software,MARC,was employed to simulate the deforming process of ECAE in order to reveal the effect of the die outer corner angle on distribution of equivalent strain field and deformation mechanism of the extruding material.The simulation results show that the distribution of equivalent strain is homogeneous when die outer corner angle is ranged between 0 and 30,however,the distribution is heterogeneity when die outer corner angle to be changed to larger than 30.Increasing of the die outer corner angle Ψ between 0 and 90,indicates that the deformation mechanism of the extrusion material has a transition from the pure share deformation to mixing deformation of the share and the bend.And a ECAE experiment to pure aluminum with large scale was conducted to demonstrate the simulation results under the channel angle of 90 and the outer corner angle of 30 to be adopted conditions,it is manifested that the distribution and value of the extrusion experiment strains of the pure aluminum are consistent with that of the simulation results approximately.Furthermore,morphologies of the pure Al explored by optical microscopy shows that the microstructure is homogeneous,and the grain size of the sample is more refined after ECAE one pass.