RETRACTED: Numerical and experimental analyses of repetitive tube expansion and shrinking processed AZ91 magnesium alloy tubes (Retracted article. See vol. 29, pg. 3039, 2015)

A novel severe plastic deformation (SPD) technique entitled repetitive tube expansion and shrinking (RTES) has been developed to fabricate ultra-fine grained and nanostructured AZ91 tubular components. This method includes two different half-cycles and is based on pressing a tubular part through an angular channel die with two shear zones. In order to primarily demonstrate the deformation behavior and refinement ability of RTES method, the FE simulations and experimental analyses were both done. Analytical calculations and FE simulations of this method accompanied by Abaqus/explicit indicate that the large amount of equivalent plastic strain of 5.8 is imposed in each cycle. In experimental investigations of a single-cycle of RTES, microstructural observations showed a significant grain refinement from the initial value of similar to 150 mu m to similar to 700 nm. The distribution characteristic of refinement and hardness were consistent with that of simulated effective strain. This novel SPD method seems to be very promising for future commercial practice.