ABSTRACT
The superplastic behaviors of a high specific strength steel (HSSS) with dual-phase microstructure and ultrafine grains have been investigated under a specific temperature range and at a wide strain rate of specific range. Superplasticity is of both academic and industrial interests because it enables the production of complex parts. Superplastic forming may be more widely used if the superplasticity can be achieved under lower deformation temperatures and at higher deformation strain rates. The UFG HSSS has the potential for the application in automobile industry due to its excellent mechanical properties. This UFG HSSS also has potential for easy superplastic forming in the industry due to its dual-phase microstructure and small grain size. However, the superplastic behaviors and the corresponding deformation mechanisms of this HSSS under high temperature tensile deformation are still unknown. Thus, the fraction of boundaries should be considered as a controlling factor for the superplasticity.
