FWF - Fließinstabilitäten - Flow instabilities and flow localization in alloys

Industrial processes such as forging and rolling to form metallic materials, involve high temperatures, large deformations and large forces. All these processes are not only used to give a form to the metallic part, but also to modify its characteristics at the microscale. This last point is relevant for the final performance of the part. On the other hand, during these processes, undesirable damage at different size scales can occur. Many efforts have been done to describe, explain, model and predict these damage caused mainly by a strong localization of the deformation. A well-established approach to model the flow localization is given by the so-called “processing maps”, in which the formability of the material is predicted at different deformation temperatures and velocities. These maps are simply built using experimental data obtained from hot compression tests done at the laboratory scale. Although to the intense use of the model, the thermodynamic and physical bases to describe it, as well as its prediction potential were questionable. In this proposal we describe a complete and detailed analysis of the phenomena of localization of the deformation, to develop a new criteria combining a large amount of experimental results, simple flow modelling and irreversible thermodynamics. The new criteria can be used for optimization of industrial forming processing of metallic parts, and its potential will be tested using examples of commercial metallic materials. The use of this method will impact directly in the quality, and thus in the performance, of mechanical and structural parts. Finally, the optimization of processing routes and the better performance of structural parts are both indirectly related to decrease the energy involved in the processing and during service, respectively. To reach our goals we will develop models, use computer simulation and carry out experiments of hot deformation in the laboratory scale.