Friction Stir Back Extrusion: Preliminary Investigations on Through-Wall Characteristics for Al-1100-O

Abstract

Friction stir back extrusion has recently been identified as a method for manufacturing stronger, more ductile seamless tubes. However, most of the work to date has investigated tubes with low length to diameter ratios and there has been little work investigating the change in grain through the thickness of the tube wall. The current project presents preliminary results in an investigation of the effect of the stirring process on developing ultrafine grain through the tube wall. The long term goal of the project is to miniaturize the process in order to produce highly ductile microscale tubes for biomedical applicaions, microscale heat exchangers, and fuel cell manufacturing applications. Friction stir back extrusion is a variation of friction stir processing and friction stir welding in that the end of a non-cutting tool rotates against a metal work piece, heats the work piece, and creates an ultrafine grain structure. The work described here considers tool speed and diameters when forming tubes from A1100-O aluminum work pieces. It was found that for rotations varying from 750 RPM to 2000 RPM that the maximum stir zone was approximately 250 μm at the bottom of the tube and approximately 50 μm in the walls. The outside diameter of the tubes was 12.5 mm and inside diameters of 6.35 mm and 9.3mm were produced.

Building on Gleiter: The Foundations and Future of Deformation Processing of Nanocrystalline Metals

“…The most well-known and well-studied SPP methods are friction stir welding (FSW) and friction stir processing (FSP). [257] Other SPP methods may include cold-spray, [37,[258][259][260] friction extrusion, friction consolidation and shear-assisted processing and extrusion (ShAPE) methods, [42,[261][262][263][264][265][266] and solid-state additive manufacturing. [267][268][269][270] In the same way that heterostructured materials are somewhat artificially collected based on heterogenous **In the opinion of the author, a very similar transition has been made between the bulk metallic glass [283,284] community and the high-entropy alloys community.…”

Optimization of friction stir back extrusion mechanical properties and productivity of magnesium AZ31-B seamless tubes

“…The self-induced heat generated due to friction between the stirring tool and the specimen and plastic deformation softens the material aiding in the outward material flow and forming a tubular shaped structure. 24 Consequently, the load needed to force the stirring tool into the billet is remarkably less than other SPD processes such as cold extrusion. Such tubular shapes can be used in various industries including aerospace and automotive.…”