Inhomogeneity in strain, microstructure and mechanical properties of AA1050 alloy during twist extrusion

In this study, inhomogeneity in the distribution of effective strain, microstructure and mechanical properties of AA1050 during twist extrusion (TE) are investigated. The samples are deformed up to 8 passes without rotation between passes. It is found that flow stress of the material increases by the number of passes. The observed percentage of the increase is more significant after two passes deformation. By increasing the number of passes to 4, smaller enhancement in flow stress occurs. As the number of passes increases to 8, a pronounced enhancement in strength is observed and fraction of high angle grain boundaries significantly increases. Microstructural analysis indicates that regardless of the number of passes, no development of cells and subgrains is observed in the central region of the specimens. In contrast, distinguished cell structure forms at the surface even by applying the first 2 passes of TE. In addition, inhomogeneity in strain, microstructure and mechanical properties are more significant at higher number of passes.