Combination of high-pressure torsion with incremental feeding for upsizing sample

This study introduces an advanced process solving the limitation involved in the process of high-pressure torsion (HPT). The HPT process is now well recognized as an effective process for significant grain refinement through severe plastic deformation (SPD) in many metallic materials including hard-to-deform materials. However, the applicability of the HPT process is limited to rather small diameters of disks or rings. The new proposed process, which we call incremental feeding HPT (IF-HPT), incorporates consecutive incremental feeding in the conventional HPT process to increase the SPD-processed area. The IF-HPT process is developed based on the principle of our recent SPD process called the incremental feeding high-pressure sliding (IF-HPS). The IF-HPT is applied to a Ni-based superalloy, Inconel 718, and it is demonstrated that the high-strain rate superplasticity is achieved with elongation well more than 400% at 1073K and an initial strain rate of 2 × 10_-2 s^-1. It is also proposed that the IF-HPT process can be used to increase the SPD-processed area by lateral feeding of the sheet sample as the IF-HPS developed earlier.