Numerical modeling and experimental investigation of brass wire forming by friction stir back extrusion

Abstract

Friction stir back extrusion (FSBE) is used to produce brass wires, and then numerical modeling is developed to model the process by the coupled Eulerian-Lagrangian (CEL) technique and verified by experiments. Next, the effects of FSBE parameters, including tool rotational and plunging speed, on the strain and temperature distributions, microstructure, and material flow patterns are studied. The results show that the highest temperature and strain occur near the tool/workpiece interface but at a further distance from the tool axis. Additionally, in the cross section of an FSBE wire, the microstructure is more refined in the sample’s periphery. A higher rotational speed or a lower plunging speed results in a coarser microstructure. The material flow pattern is a conical helix and does not change meaningfully by the process parameters. The points at the further distance from the tool axis, along with an upward movement, experience an inward spiral motion which is amplified by higher rotational speed. However, the materials near the tool axis almost take an upward movement and endure a significantly lower strain.