Achieving superplasticity in hard-to-deform metallic materials using high-pressure sliding (HPS) process

Abstract. This presentation shows that superplasticity is achieved in hard-to-deform materials when they are processed by severe plastic deformation (SPD) through high-pressure sliding (HPS). The HPS process is similar to the high-pressure torsion (HPT) process as the straining is made under high pressure in highly constrained conditions. It is applicable to a sheet form of samples while the HPT process uses disks or rings, and thus it has advantage that the sample size can be increased. In addition, when the HPS process is combined with a feeding process, the SPD-processed area can be further enlarged without increasing the machine capacity, of which process is called the incremental feeding HPS (IF-HPS). The HPS process is applied to a Ni-based superalloy (Inconel 718), a Ti-6Al-7Nb alloy (F1295) and a Mg-6Al-1Zn alloy (AZ61), and superplasticity is well attained in all the hard-to-deform alloys with total elongations more than 400%. It is also demonstrated that cup forming of the Inconel 718 with practical dimensions is realized by application of the IF-HPS process.