Microstructure Evolution and Mechanical Property Characterization of 6063 Aluminum Alloy Tubes Processed with Friction Stir Back Extrusion

Abstract

Friction stir back extrusion (FSBE) is a technique for lightweight metal extrusion. The frictional heat and severe plastic deformation of the process generate an equiaxed refined grain structure because of dynamic recrystallization. Previous studies proved that the fabrication of tube and wire structures is feasible. In this work, hollow cylindrical billets of 6063-T6 aluminum alloy were used as starting material. A relatively low extrusion ratio allows for a temperature and deformation gradient through the tube wall thickness to elucidate the effect of heat and temperature on the microstructure evolution during FSBE. The force and temperature were recorded during the processes. The microstructures of the extruded tubes were characterized using an optical microscope, energy-dispersive x-ray spectroscopy, electron backscatter diffraction, and hardness testing. The process reduced the grain size from 58.2 lm to 20.6 lm at the inner wall. The microhardness of the alloy was reduced from 100 to 60-75 HV because of the process thermal cycle. tract No. DE-AC05-00OR22725 with the US Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/do e-public-access-plan).

Parameter Optimization of the Forging and Forming Process Using Particle Swarm Optimization

“…The specific data of the billet is the diameter of 90mm, the length of 250mm, and the inner diameter of the extrusion cylinder of 96mm. The hollow circular tube produced has an outer diameter of 60 mm, an inner diameter of 56 mm and a wall thickness of 2 mm [8]. Subsequent forging simulations will be carried out according to the data of the aluminum alloys in Table 1 into the simulation software.…”

Harnessing friction stir back extrusion process to fabricate microtubes from as-cast Mg–4Zn–0.7Zr-1.6RE magnesium alloy

“…AZ31B grade magnesium alloy seamless tubes were produced using the FSBE process by Miller et al [8] and reported the grain size and morphology variations along the tube wall. Zhang et al [9] produced thick-walled aluminium alloy tubes and found a grain size gradient from the interior to the exterior surface of the tube wall. Jarrah et al [10] evidenced a more considerable variation in the metal flow behaviour, strain rate, and temperature between the inner and outer wall during the manufacturing of AZ31B magnesium alloy tubes via the FSBE process.…”

Optimization of microstructural and mechanical properties of brass wire produced by friction stir extrusion using Taguchi method

“…However, by technological advancement, new recycling techniques have emerged, such as the friction stir back extrusion (FSBE), enabling the shops to recycle the metal chips into extruded products directly. 9 , 10…”

“…Previously, friction-based processes such as friction welding methods have demonstrated their capability in joining and forming the materials in solid-state and have introduced products with desired mechanical properties. 10–12 Recently new friction stirring concept was developed, which targets the processing and recycling of chips to generate a bulk material. The FSBE, as a solid-state recycling technique, produces frictional heat to soften the recycling chips, and then, by applying adequate pressure as a forging force, the chips are merged and then pushed to a channel to produce an integrated product like a wire or tube.…”