Abstract
Friction stir back extrusion (FSBE) is emerging as a novel method to produce high
strength fine grained metallic tubes. The objective of the present work is to produce
aluminum seamless tubes from solid cylindrical bars using FSBE and to report the
microstructure and mechanical characterization. A die, tool and fixture were designed to
carry out FSBE. A conventional friction stir welding machine was utilized for FSBE. A
cylindrical bar of aluminum alloy AA6061-T6 was kept inside the hole in the die and
extruded by plunging the rotating tool. The microstructure of the produced tubes was studied
using optical microscopy. The microstructure was found to be homogeneous along the tube.
The microhardness and compressive strength of the tube are presented in this paper. The
results indicate that FSBE process is capable of producing sound aluminum seamless tubes.