In order to model metal forming processes either by theoretical models or by FEM modeling, as already shown in Ch. 3, it is required, for instance, to know the flow stress of the metal that is formed, and the actual friction between the die and the workpiece. To obtain such data, a number of different test methods have been developed over the years, by which it is possible to bring a specimen of the actual material, usually of small size, into a plastic state, and during plastic deformation of it measure the required deformation force, concurrently as the size of deformations subjected to the specimen is measured. Tests of this kind are called technological tests and are commonly run on small specimens of the material, often in advanced equipment especially designed for the purpose. In this chapter, the most common technological tests for measurement of flow stress and ductility of metallic materials are discussed. The main focus will be on the tensile test and the compression test. The basic mechanics of these technological tests, and how to determine stresses and strains during the tests, will be reviewed.

Physical Simulation of Metal Forming

Some industrial metal forming processes – as for instance rolling, extrusion, and forging – are commonly run in large industrial equipment, where the possibilities of experimentation is limited. Most commonly the machinery lacks sensors to allow accurate recording of relevant process parameters. Moreover, running of full-scale experiments in big industrial equipment is expensive.