Characterization of the Influence of Rotational and Traverse Speeds on the Mechanical and Microstructural Properties of Wires Produced By the FSBE Method

This study investigates the effects of tool traverse and rotational speeds in the friction stir back extrusion (FSBE) process on the microstructural and mechanical properties of brass wires produced. The microstructural properties were examined by microscopic tests and the mechanical properties of the wires by hardness and pressure tests. The material flow pattern, temperature history, and strain experienced by the materials were investigated using a numerical model to understand better the effects of tool traverse and rotational speed on the final properties of the wires. Numerical results showed that, on the one hand, the strain experienced by the material in the wire periphery is more than the center of the wire, and on the other hand, the material experiences a lower temperature in the wire periphery. The microstructural results showed that this more significant strain and lower temperature in the perimeter of the wires caused the grain size to be finer than the center of the wire. Moreover, a coarser microstructure is produced by a faster rotation speed or a slower traverse speed. Also, increasing the traverse speed or decreasing the rotational speed increased the hardness of wires produced, so that the sample made with a traverse and rotational speeds of 40 mm/min and 315 rpm had the highest hardness, and the wire made with a rotational speed of 800 rpm and a traverse speed of 25 mm/min had the lowest hardness.