On the role of residual austenite in improving the complex of properties of ductile cast iron

Abstract

This article is analyzing the prospects and ways to expand the field of applying ductile cast iron-high-strength cast iron in technology. Ductile cast iron occupies a special place among structural materials. With the same level of mechanical properties, having less specific weight than steel, it provides less weight of products in comparison with steel. This reduces the consumption of raw materials and energy resources in the manufacture and operation of machines and mechanisms. There is a positive effect both in terms of economy and ecology. In addition, ductile cast iron has better casting properties than steel. In recent years, scientists and engineers have focused their efforts on finding new ways to improve the complex of mechanical and operational properties of ductile cast iron. This will make it possible to expand the field of their application and obtain additional advantages. A very effective direction – obtaining bainite matrix and a great amount of stable austenite in the structure of ductile cast iron by heat treatment allows to realize martensitic transformation in the most loaded parts during their operation and thereby increases adaptability. In this case, in addition to the traditional type of heat treatment - one-stage isothermal hardening, the technology of two-stage isothermal hardening is actively implemented, which allows for providing more dispersed ferrite and more stable austenite in the structure. A fundamentally new approach to obtaining the favorable microstructure of ductile cast iron is the organization of a foundry and heat treatment complex that makes it possible to obtain the ferrite-austenite mixture in the structure of ductile cast iron directly from the cast state, bypassing a separate heat treatment operation