The flow characteristics of superplasticity

1Division of Materials Science and Engineering, Hanyang University, 133–791, Seoul, South Korea 2Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453, USA CA 90089–1453, Los Angeles, USA 3Department of Materials Engineering and Civil Construction, Universidade Federal de Minas Gerais, Belo Horizonte 31270–901, MG, Brazil 4Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, SO17 1BJ, Southampton, U.K Attaining superplastic elongations is an important prerequisite for using metals in commercial superplastic forming applications. This review briefly summarizes the principles of superplasticity in conventional materials and then demonstrates that similar behavior, for both the flow properties and the cavitation characteristics, may be attained in ultrafine-grained materials with submicrometer grain sizes produced through the application of severe plastic deformation (SPD). An advantage of using SPD processing is that the regime of superplastic flow is displaced to faster strain rates and often occurs within the region of high strain rate superplasticity.