Improvement in the r-value of aluminum sheets by differential-friction rolling

Differential-speed rolling can improve the formability of aluminum alloys through the formation of shear texture. The authors propose an alternative asymmetric rolling method. The asymmetry is achieved by differentiating the friction on the upper interface from that on the lower interface. A commercial aluminum sheet in which one surface was coated with PTFE was rolled. The shear strain introduced was comparable to that introduced by differential-speed rolling. The annealed sheet showed a higher r-value than the symmetrically rolled sheet.