Temperatur- und Konzentrationsausgleich unter Vernachlässigung von Ortsabhängigkeit (English shop)

thermisch aktivierte und reaktionskinetisch determinierte Anwendungen in der Werkstofftechnik

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It is shown how kinetic aspects of heat conduction, temperature equalisation, diffusion and material properties can be described on a largely similar physical basis. Use is made of approximate solutions of heat conduction and diffusion theory, with preference given to conditions under which the spatial dependencies of the temperature and diffusion gradients can be regarded as of secondary importance or even negligible. The modelling approaches compiled for diffusion and reaction kinetics, together with the application examples presented, convey a specific section of the very broad field of thermally activated material modification. The model abstractions can be applied to particular advantage whenever a more in-depth treatment in terms of metal physics is not possible or would be too costly. The reaction-kinetic model is always aligned with the specific experiment and, by means of parameter identification (through numerical solution of the inverse problem as a nonlinear least-squares problem), effectively calibrated. Conversely, the model then indicates under which process conditions, or in which experimental ranges, it may be expedient to plan or add further experiments. The concept thus enables efficient—because evolutionary—experimental design and execution. Above all, however, the concrete models can show the engineer in practice which thermal process settings need to be made in order to target and achieve desired material properties. A number of case studies—including on thermally activated softening, the kinetics of scaling, phase transformation, sintering kinetics, the diffusion of surface layers, press hardening and draw annealing, as well as hydroforming—serve to further explain the modelling of thermally activated material reactions, processes that have proven their worth in research and industry.