摩擦对反复镦压工艺的影响

Investigation of the effect of friction on cyclic channel die compression process

反复镦压被认为是一种有应用前景的制备块体超细晶材料的方法.文中借助有限单元法研究了摩擦因子对镦压试样等效应变大小及分布、速度场以及变形载荷的影响.研究结果表明,由于摩擦的存在,试样同一截面各点沿纵向的流动速度并不一致.镦压后试样内部的等效应变分布不均匀,除角部区域小范围内等效应变较高外,其它部分中心区域等效应变较高.随摩擦因子增大,试样的平均等效应变略有增加,但等效应变分布的均匀性明显下降.最大变形载荷随摩擦因子的增大而显著增加.因此,应采取适当的措施降低摩擦的影响.

Cyclic channel die compression(CCDC)process is regarded as a promising method for fabricating bulk ultra-fined materials.The effect of friction on the magnitude and distribution of effective strain,velocity field and deformation load were investigated by finite element method(FEM)in this paper.The results show that the velocity of same section is different along the longitudinal direction due to the existence of friction.The distribution of effective strain in the samples is inhomogeneous.The effective strain is high in the central area apart from some corner area.The average effective strain of the sample increases slightly with the increase of friction coefficient.But the distribution homogeneity of effective strain decreses obviously.The maximum deformation load increases quickly with the increase of friction coefficient.So appropriate measures should be taken to decrease the effect of friction.