The effect of cyclic torsion on the dislocation structure of drawn mild steel

Abstract

Cold forming is usually associated with the "work hardening" of the material being formed. The work hardening behavior of metals subject to complex processing paths is different from that in monotonic deformation. The results show that, after some initial hardening, there is a possibility that further deformation will cause softening in the material ("work softening"). Recent work showed that cyclic torsion applied to drawn products causes changes in the subsequent tensile behavior of low carbon steel, and that the effect will depend on the previous "history" of the material. For annealed samples, the cyclic torsion leads to an increase in the yield strength, but does not affect the tensile strength and elongation. For the case of previously drawn bars, the cyclic deformation caused a decrease in the yield and tensile strength and an increase in the total elongation. The present paper discusses the dislocation structure changes associated with different strain paths in mild steel

The finite element analysis of equal channel angular pressing (ECAP) considering the strain path dependence of the work hardening of metals

“…The available results cover various sheet processing routes [11][12][13][14], compression after extrusion [15], bar drawing followed by tension [16][17][18], successive shearing at various directions [19], and monotonic straining followed by cyclic straining and vice versa [20][21][22][23]. Strain path changes can lead to increased or decreased flow stresses and strainhardening rates (including strain-softening) in relation to the behavior of the material before the strain path change.…”