Isothermal Transformations in High-Strength Cast Iron

Relevance. The technological process of manufacturing parts from high-strength cast irons is simpler and more economical than the process of manufacturing parts from steel. Cast irons are less sensitive to stress concentrators and strike loads. Spheroidal graphite cast irons can achieve DI 70 grades even in the cast state. Through hardening heat treatment or additional alloying, it is possible to produce cast irons of higher strength (grades DI 80 and above). As the strength properties of cast irons increase, disadvantages in the form of low ductility and plasticity become increasingly apparent. These problems can be compensated by providing an ausferritic, bainite or bainite-austenitic structure of the metal matrix of cast irons. A good solution is to obtain cast irons with a complex structure of the bainite-ausferrite type. In this regard, the relevance of this work is due to the fact that, in the practice of modern mechanical engineering, high-strength cast irons are increasingly used.

Purpose. The purpose of this work is to study and obtain the bainite structure due to isothermal hardening. To achieve which specific features of isothermal transformation in high-strength cast iron with spheroidal graphite have been considered.

Methods. This research was based on a theoretical method (analysis, synthesis, concretization, generalization, modeling), and empirical methods (study of research experimental works of scientists and their experience in this or similar field with the application of similar designs and study by experienced specialists).

Results. The possibility and efficiency of obtaining the bainite structure in economically alloyed nickel, copper and molybdenum, in the amounts, respectively, of 1.0; 0.5 and 0.5%, of cast irons using continuous cooling in air has been established.

Conclusions. The results and conclusions formulated on their basis can be used in the future as an effective scientific basis for studying the prospects of application of isothermal hardening of alloyed and unalloyed high-strength spheroidal graphite cast irons

ausferritic cast iron, isothermal hardening, spheroidal graphite cast iron, bainite, austenitization