Decisive influence of critical process parameters on the microstructure and tensile properties of friction stir back extruded magnesium alloy tubes

Friction Stir Back Extrusion (FSBE) is evolving as a novel extrusion process for producing high strength ultrafinegrained
tubes from a range of metallic alloys. This investigation focuses on developing a high-fidelity experimental
methodology to control the critical process parameters of the FSBE process for manufacturing high
strength ZE41 magnesium alloy tubes. The crucial parameters of FSBE required to manufacture highly reliable
ZE41 tubes were determined with solid evidence obtained through a wide range of thorough experimental trials
on ZE41 magnesium round rods. The metallurgical characterisation was performed at key regions across the
tubes obtained using the ideal process conditions to understand the influence of FSBE process parameters on the
microstructural formation. Mechanical properties of the tubes were evaluated and found that the tubes produced
at optimum conditions have achieved high tensile and hoop strengths. The microstructure-mechanical property
correlation confirmed that the FSBE process driven with the controlled process parameters enable to produce
defect-free high strength ZE41 magnesium tubes with a significant enhancement in grain refinement.