Homogeneous Strain Introduction Using Reciprocation Technique in High-Pressure Sliding

This study examines strain distribution occurring in the high-pressure sliding (HPS) processing for rods of pure Al and an AZ61 alloy. The strain distribution is evaluated through the optical micrographs and hardness measurements on the cross sections at the positions of the front, center, and rear along the longitudinal axis with respect to the shearing direction. The advent of superplasticity is also used for the evaluation of sufficient introduction of strain and thus grain refinement. The strain distribution is also measured on the longitudinal cross section by marking square grids and measuring the change in grid shapes after the HPS processing. This direct measurement on the longitudinal cross section is compared with an FEM simulation. It is shown that strain is preferentially introduced in an oblique direction. Reciprocation of the sliding direction is a good solution for this inhomogeneous strain introduction. Rotation of the rod around the longitudinal axis after each sliding pass is also effective to improve the homogeneous strain distribution on the vertical cross section of the rod. It is suggested that reciprocation of the sliding direction together with rotation of the rod around the longitudinal axis promotes the homogeneity of the strain distribution.