Heat treatment of Ni–Mn–Cu cast iron

Examined was the influence of chemical composition defined by the nickel equivalent, as well as time and temperature of soaking on course of decomposition process of metallic matrix in the austenitic Ni–Mn–Cu cast iron. In alloys with the equivalent value ranging from 16.0% to 23.0%, with properly selected heat-treatment parameters, possible is controlled, partial transition of austenite to hard acicular ferrite. Obtained is the structure morphologically corresponding to that of ausferrite, characteristic for cast iron quench-hardened with isothermal transformation (e.g. CGI or ADI). Replacing the quench-hardening operation by soaking permits, among others, obtaining homogeneous structure in the entire cross-section of solid thick-walled castings or elimination of quenching stresses.