Inhomogeneity Through Warm Equal Channel Angular Pressing

摘要

In this study, the hardness inhomogeneity of billets during multi-passes of equal channel angular pressing (ECAP) at elevated temperatures is investigated and the effect of large strain deformation during ECAP on the hardness inhomogeneity characteristics due to dynamic aging of aluminum 6061 under a variety of temperatures and ram speed was studied by TEM and hardness measurements. The hardness results showed that the hardness distribution is more homogenous after four passes using the pressing route B_c. However, when the deformation temperature was considered, performing ECAP at 100℃ may provide the most homogeneous microstructure after multi-pressing as long as the total number of pressing passes is four. This indicates that a lower temperature (in the range of warm working) is favorable for achieving an ultrafine-grainedanomaterial with a more homogenous microstructure. In order to quantify the inhomogeneity in the cross section of the as-pressed sample, an inhomogeneity index has been defined. The results show an increase in the hardness in the first pass with significant inhomogeneous deformation and a transition toward a more homogeneous structure with subsequent passes.