Producing Ultrafine Grain Al6061 Alloy by Accumulative Back Extrusion Process

Accumulative back extrusion (ABE) is a kind of severe plastic deformation process to refine the microstructure, resulting in significant improvement in mechanical properties. In the present study, AA6061-T6 alloy was subjected to a newly designed ABE process at room temperature. One cycle of ABE was employed to the workpiece. The microstructural evolution was then characterized using optical microscopy and transmission electron microscopy (TEM) techniques. The results show that after one cycle of ABE, significant grain refinement was achieved. This led to the formation of ultrafine grains of smaller than 1???m. Besides, there was about a two-fold increase in the hardness, increasing from approximately 88 Hv to 155-160 Hv after only one cycle of ABE.