Superplastic Flow

Superplasticity is the ability of polycrystalline materials under certain conditions to exhibit extreme tensile elongation in a nearly homogeneous/isotropic manner. Historically, this phenomenon was discovered and systematically studied by metallurgists and physicists. They, along with practising engineers, used materials in the superplastic state for materials forming applications. Metallurgists concluded that they had the necessary information on superplasticity and so theoretical studies focussed mostly on understanding the physical and metallurgi­ cal properties of superplastic materials. Practical applications, in contrast, were led by empirical approaches, rules of thumb and creative design. It has become clear that mathematical models of superplastic deformation as well as analyses for metal working processes that exploit the superplastic state are not adequate. A systematic approach based on the methods of mechanics of solids is likely to prove useful in improving the situation. The present book aims at the following. 1. Outline briefly the techniques of mechanics of solids, particularly as it applies to strain rate sensitive materials. 2. Assess the present level of investigations on the mechanical behaviour of superplastics. 3. Formulate the main issues and challenges in mechanics ofsuperplasticity. 4. Analyse the mathematical models/constitutive equations for superplastic flow from the viewpoint of mechanics. 5. Review the models of superplastic metal working processes. 6. Indicate with examples new results that may be obtained using the methods of mechanics of solids.

The present book aims at the following: - To outline briefly the techniques of mechanics of solids, particularly as it applies to strain rate sensitive materials, - to assess the present level of investigations on the mechanical behaviour of superplastics, - to formulate the main issues and challenges in mechanics of superplasticity, - to analyse the mathematical models/constitutive equations for superplastic flow from the viewpoint of mechanics, - to review the models of superplastic metal working processes, - to indicate with examples possible new results that can be obtained using the methods of mechanics of solids. It is intended for a variety of readers who may be interested in the phenomenon of superplasticity for different reasons: materials scientists and physicists working in educational institutions and R&D units, those who wish to work on the applications of superplasticity, engineers in industry, students at senior undergraduate and postgraduate levels and those who wish to understand the phenomenology and mechanics of superplasticity without involvement in actual research. A reader who has exposure to standard differential and integral calculus and elementary tensor calculus at a level taught to senior undergraduate students at a technical university should have no difficulty in following the treatments. The analytical procedures are explained in an Appendix with simple examples.