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SUMMARY Brief consideration is given to several mechanical tests for the measurement of metal formability. The compression test is considered in some detail, and its usefulness in the calculation of forming limit lines and as a source of information on the feasibility of forming processes is demonstrated. INTRODUCTIONThe manufacture of many engineering components involves the deformation of metals and alloys. Deformation processes are relatively simple and yield products with good mechanical properties. Traditionally, the feasibility of a forming process was determined to a great extent by trial and error. Even today, many concerns rely on experience and operator skill for the successful manufacture of components. This approach often leads to the production of defective components that have to be scrapped, and time is lost while tools are modified or redesigned. Recent research has shown that formability tests can be useful in predicting the behavior of a workpiece under industrial conditions. Thus, the feasibility of a process can be determined in the laboratory at relatively low cost. Many formability tests have been used by various investigators whose choice of test appears to be governed by the availability of equipment and the nature of the forming process under consideration. This paper presents a review of the literature to illustrate the present· state of the art. FORMABILITYFormability can be defined as the amount of deformation that a material will withstand without fracture in a particular metal-working process. 1 . 3 It is not a unique property of the material, but depends on such process variables as the stress system, strain rate, temperature, and friction conditions can be ductile under hydrostatic pressure. 4 Metallic materials can be deformed to a greater extent by extrusion than by drawing, owning conditions can be ductile under hydrostatic presure. 4 Metallic materials can be deformed to a greater extent by extrusion than by drawing, owing to the compressive nature of the stresses which prevent fracture. In a drawing operation, the amount of deformation is limited by the tensile stress on the drawn material.The concept of formability can be expressed by the following relationship.1.awhere f1 is a function of the basic ductility of the material, and f2 is a function of the stress and strain system imposed by the process. It follows from this relationship that in determining formability it is necessary for one to establish (1) a fracture criterion to determine the state of stress or strain (or both) at fracture as a function of strain rate and temperature (f1), and (2) a description of stress, strain, strain rate, and temperature histories at potential fracture sites (f2).A complete analysis of formability can then be accomplished by comparison of the results of flow analysis with the limiting conditions defined by the fracture criterion.TECHNIQUES FOR TESTING FORMABILITY Metal formability can be assessed by the use of different techniques such as tension, torsion, bending, and compression tests....

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