Accumulative back extrusion (ABE) processing as a novel bulk deformation method

A novel severe plastic deformation method based on an accumulative back extrusion (ABE) processing is proposed. In this process a cylindrical work piece is placed into the bottom die with the same diameter. A twin punch setup, designed to slide through each other, is the heart of this novel method. The inner punch with a predetermined diameter is forced into the work piece. This causes the excess material to flow through the gap between the die and the inner punch. This ends to a cup shape specimen. The latter is then compressed back by outer punch under geometrical constraint towards the original shape. The whole process can be repeated as many times as programmed. The method may introduce ultra-high plastic strains without any geometrical change. This has been applied to a commercial Mg–3Al–1Zn alloy and a significant grain refinement was achieved even after single cycle ABE.