Kalashnikova A. Improvement of technological processes of castings obtaining from modified wear-resistant cast irons for the metallurgical and mining industries.

Thesis is devoted to the improvement of technological processes of casting of white wear-resistant cast irons with different degree of doping to provide increased mechanical and exploitational properties of castings. Experimentally established and obtained mathematical dependence of the joint influence of the main factors of the technological process on the structure, mechani-cal and exploitational characteristics of wear-resistant cast iron used for production of grinding bodies. Development is characterized by a comprehensive consideration of the influence of key technological factors of production such as: mold’s material, de-sign of the mold, maturing time of casting in the mold, temperature of the casting ex-traction, the cooling environment, and alloy modification on the exploitational prop-erties of the castings. Developed rational technological process of casting is provided an opportunity to produce castings with increased performance characteristics. Also developed, discovered and verified on the production more efficient design of metal mold which has cooler and has been investigated process of crystallization inside it-self, which provided possibility to significantly decrease weight of metal mold and effective thermal conductivity of it. Temporal and thermal parameters were developed and for the first time inves-tigated under laboratory conditions, and as result defined optimal temporal parame-ters between the crystallization of main layer of alloy, which has been modified by the modifier contained rare-earth metals (REM), and beginning of the process of bi-metallic roll flushing. The development is characterized by using of the high-layered differentiated, according the thermal zones, 3D model. Using of the created approach with computing modelling provided us with the possibility to improve existing tech-nology of bimetallic rolls production in combined molds based on the flushing tech-nology. Also, has been defined the influence of the working layer alloy modifying by the modifier contained REM, and complex using of the heat treatment on the struc-ture formation and mechanical characteristics of the cast-iron alloy. Research is char-acterized by using of the modifier based on the rare-earth metals with the targeted impacting on the structure formation of the bimetallic rolling rolls. Such complex ap-proach allowed us to provide improvement of strength and exploitational properties of the working layer alloy with simultaneous decrement of alloying materials con-suming. Complex structure and strength research for the of chromium cast iron alloy with lower containing of alloying elements under the influence of modifier has ob-tained further progressing. It provides possibility to develop cast iron alloy with higher strength and exploitational properties with simultaneous decreasing of alloying materials consuming. Also, please note that developed alloy does not require any ad-ditional heat treatment. Technological parameters of higher quality castings produc-tion were created, researched and tested under the production conditions. Considering the ecological context, using of modifier contained rare-earth metals according to the improved technological processes has positive affect.