Polishko H. Scientific foundations of electroslag process with liquid metal for solid and composite ingots manufacturing.

This work is devoted to increasing the efficiency of electroslag remelting and both quality and stability of the steels and alloys properties due to creating favorable conditions for ingot formation. The dissertation develops theoretical grounds of physicochemical and heat and mass transfer processes at the ESR. It checks the new practical approaches to their implementation using liquid metal instead of the consumable electrode. It offers the application of new technological schemes of Electroslag Remelting with Liquid Metal and the practicality of their use for the production of heavy ingots for critical parts (i.e. composite rotor for modern power turbines and premium quality rails). Comparison analysis of the physicochemical and mass transfer processes at the ESR (with a consumable electrode with a fill factor 0.6…0.7) and the ESR LM has shown that in the last case the total surface of interaction is twice less, and overheat of metal coming into the mould is 70…90 K lower. Reducing the metal overheat allows increasing the ESR LM process productivity compare to the classic ESR up to 15% while maintaining the same quality of the ingot. It was stated, that the film on the tip of an electrode at classical ESR is not the critical stage in the process of refining from sulfur, because at the ESR LM at no consumable electrode the same degree of sulfur removal was reached. connection. Computational-analytical and experimental substantiation of the hybrid process combining electroslag heating of the metal meniscus and continuous casting of steel (ESR+CC) to reduce the rate of the casting (withdrawing) without disturbing its surface formation was made. It is expedient for long products (railway rails and axles, heavy beams and channels, etc.) as was checked on the example of rails made of high-strength steel. Industrial tests have shown the possibility of ESR slag ANF-28M (40/15/25/15/5) using on the caster (CC) meniscus. The use of the ESR way for the meniscus heating allows reducing the withdrawing speed of a billet by almost three times, thus, to improve the internal structure, density and homogeneity of the billet metal while maintaining the quality of its surface. Schemes for the ESR LM implementation as part of a hybrid process for CC using a current-supplying mould and the electroslag remelting way for rails production at a micro-mill were developed.