After a recruitment phase, seven MIMESIS students began their work in February 2016, one student started in May 2016. Four students had a background in materials science, the other four in applied mathematics and computational engineering.
Supported by an interdisciplinary training program between materials science and applied mathematics and secondments to at least two industrial partners, the students worked on ambitious PhD projects combining expertise in materials science and applied mathematics and covering a broad range of topics centred around three major topics - induction heating, phase transformations in steel alloys, and ladle stirring.
Two of the theses concern hardening: one was on the hardening of helical and bevel gears by an optimized single or multi-frequency approach. and the other is a novel idea about the hardening of the inner surface of pipes. Here, main achievements were the development of computational tools for a systematic approach towards induction coil design and experimental work using a thermomechanical simulator together with numerical simulations, which helped to find a feasible path to create a graded material structure with extremely good wear resistance on the inner surface leading also to a number of research papers involving two companies.
Two of the theses are related to induction heating applications, for the production of high-frequency welded pipes and for pre- and post-heating in the thermal cutting of steel plates. In high-frequency tube welding a break-through result could be achieved for the process simulation. An improved modeling of spatially dependent velocities in combination with a numerical stabilization procedure allowed for the first time for a complete three-dimensional process simulation with arbitrary feed velocities. Concerning the thermal cutting of steel plates, the consequential use of modern optimal control methods for partial differential equations allowed the computation of optimal preheating strategies and a feasibility study as a decision support tool for investing in this new technological approach.
Two further theses were concerned with phase transformations during steel production. The first one broadened the knowledge of quantitative prediction of intergranular corrosion while the second one achieved a better understanding of the microstructure of as-quenched low-carbon auto-tempered martensitic steels, which will help in making better, environmentally efficient, lightweight, and high-strength steels.
The final two theses were related to secondary metallurgy in the ladle. In the first one, computational fluid dynamics models of ladle treatments have been used to optimize the alloying practice and to reduce the consumption of nickel as an alloying element. The last one achieved an improvement of ladle stirring monitoring and control based on an optimal control approach utilizing vibration measurements.
The research work has led to seven PhD theses, one student took a parental leave in the last stage of his contract and decided not to come back and finish his thesis. The ESRs presented their achievements in international conferences and university seminars in Europe, America, and Asia. Moreover, they participated in activities like the “Long night of sciences” where they presented their work to the general public.
Practical aspects, simulation strategies and developed models have been taken up by the companies and will lead to further collaboration with the scientific partners.
