Applicability of a modified backward extrusion process on commercially pure aluminum

• Modified novel backward extrusion process was presented.
• Higher plastic strain of ∼3.5 were obtained.
• Deformation zone geometry was modified.
• Hardness was increased to about 63 Hv from the initial value of ∼40 Hv.
• Better strain homogeneity and higher hydrostatic stress was applied.

In this study, a modified novel backward extrusion process implementing severe plastic deformation is presented for processing of ultrafine-grained materials. Deformation zone geometry was modified by elimination of mandrel’s fillet for enhancing plastic strain and adding particular slope. Finite element analysis has been revealed higher strain value and more strain uniformity in this process. The process was applied to commercially pure aluminum, and microstructure and microhardness measurements were investigated. Surveying of microstructure in extruded specimen showed significant grain refinement resulted from the higher plastic strain of about 3.5 after only single pass new process. Uniform equivalent plastic strain through the thickness and length of the sample was achieved. Higher hydrostatic compression stress resulted from new die geometry limits the formation of any defects. Microhardness evolution in extruded part showed more than 52% improvement.