Efremenko A. The increasing of impact-abrasive wear resistance of steels in corrosive water-based solutions by improving of chemical compound and microstructure

The object of study is the phase-structural factors that determine the wear resistance of alloys in various conditions of wear. The goal is to improve the chemical composition and microstructural state of steel, providing the achievement of high resistance to impact-abrasive wear in the presence of corrosive water media. The subject of study is the influence of chemical composition and microstructure of steels and cast irons of different systems and doping level on their resistance to the shock-abrasive wear in the presence of corrosive aqueous solutions. Methods: metallographic, microprobe and X-ray analysis techniques, scanning electron microscopy, measurement of macro-and micro-hardness, corrosion testing, the definition of wear resistance in the laboratory and industrial conditions, the mathematical design of experiments. The the innovation of work - the concepts of wear resistance of steels and cast irons concerning the impact-abrasive-corrosive wear have been further developed, the ranking of alloys with increase in their wear resistance in water solutions of salts, acids and alkalis with a pH of 1 to 14 is established; it is shown that level to wear resistance in greater degree is contributed to microstructural factor, rather then chemical composition and corrosion resistance. That makes the alloys with less quantity of alloying adds to be the most effective according to correlations "wear resistance - price". The maximum of wear resistance is providing by getting of austenite-martensite structure with no secondary carbides containing 65-75 % of retained austenite which transforms into martensite during wear process; the character of mechano-chemical reactions during wear have been found, it has been shown that 70 % of wear is related to the phenomenon of tribocorrosion synergy, which in 67,0-99,8% caused by increasing mechanical wear under the influence of corrosive medium; it the reasonability of alloying by copper to improve the impact-abrasive-corrosive wear resistance of low-alloy steels has been shown. The degree of implementation: the chemical composition of new low alloyed steels 115ХГ2С1Ю, 75ХГ2С1ЮД1, 75Г2С with high impact-abrasive-corrosive wear resistance and modes of their heat treatment have been developed. Results have been implemented into the production of grinding balls in the "Azovstal" Steel Works with economic benefit of 671 th. UAH. Scope of use - mining and metallurgy.