Nizhniy Novgorod State Technical University (Nizhniy Novgorod, Russia)

V. A. Korovin, Dr. Eng., Prof., Dept. “Metallurgical Technologies and Equipment”, e-mail: v.korovin2015@yandex.ru
I. O. Leushin, Dr. Eng., Prof., Dept. “Metallurgical Technologies and Equipment”, e-mail: igoleu@yandex.ru

Kazan National Research Technical University named after A.N. Tupolev – KAI (Kazan, Russia)¹ ; Kazan Federal University (Kazan, Russia)²

I. P. Balabanov, Cand. Eng., Associate Prof., Dept. “Automation and Management”; Associate Prof., Dept. “Design
and Technology for Machine-building industries” ^1,2, e-mail: balabanovip@mail.ru

Kazan National Research Technical University named after A.N. Tupolev – KAI (Kazan, Russia)
I. A. Savin, Cand. Eng., Associate Prof., Head of Dept. “Design and Technology for Machinebuilding industries”, e-mail: savin.ia@kaichelny.ru

In this paper the authors examined the problem of insufficient operating resistance of moulds which are used for manufacture of steel ingots. Massive moulds, usually made from cast iron and sometimes from carbon steel, are used conventionally for production of steel ingots. Operating resistance of moulds depends of many factors and it can be maximized when three most important requirements are executed: structural strength; resistance to slopping of internal surface of mould walls during contact with liquid steel melt; ability of mould walls to hold thermal and mechanical effects. Satisfaction of the first two requirements is achieved via varying the mould wall thickness, while meeting the third requirement is determined by correct material choice. This choice, in its turn, is impossible without deep analysis of the problems occurring during mould operation and signs of their reject, such as cracks, erosion nets and burn-backs. Improvement of mould material parameters during their manufacture via casting seems to be the most prospective solution for increase of mould resistance. In this connection, the described research was aimed on formulating the scientifically substantiated choice of the initial material for moulds, which are used for manufacture of steel ingots in the conditions of the operating industrial production facilities (1), and the complex of experimental investigations in order to improve parameters of this material via technological methods of liquid phase treatment (2). The ingots made from carbon steel were chosen as initial material, while modifying and microalloying by the complex modifier INSTEEL-7 (produced by NPP “Tekhnologiya”, Chelyabinsk) were used for liquid phase treatment of initial material for improvement of its properties. Based on the results of conducted pilot-experimental work, the following parameters were obtained: increase of impact toughness for modified metal almost by two times (in comparison with conventional metal), rise of tensile strength and yield strength by 8.5 % and 20 % respectively, decrease of relative elongation and area reduction by 27 % and by three times respectively, what provided increase of operating resistance of a mould more than by 2 times as a result.

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