3. Plasticity, Formability, and Materials

This chapter begins with the definitions of plasticity and formability from a manufacturer’s perspective. The stress–strain curve is illustrated with reference to yielding, strain hardening, and necking. The condition of plastic instability is established by deriving mathematical relationships. The techniques for improving formability are elaborated both theoretically (graphically) and from an industrial-application point-of-view. Superplasticity is explained by establishing the microstructural requirements for super-plastic forming (SPF) with the aid of illustrations. Since metal forming deals with deformation of metallic materials, the latter are discussed with reference to their mechanical behavior, especially their formability. Finally, an overview of formable ferrous alloys and formable non-ferrous alloys is given, which includes their classification, microstructures, mechanical properties data, and the effects of composition and processing on the mechanical properties. This chapter contains 10 diagrams, 13 formulae/equations, 3 tables, 8 worked numerical examples, 5 problems, and 14 MCQs with their answers, provided at the end of the book.