Uniform Dispersion Mechanism of Carbides by Subcritical Annealing at below A<sub>1</sub> Transformation Temperature for High-chromium Case-hardening Steels

In the JIS standard case-hardening steel, spheroidizing annealing can improve cold forgeability but inevitably results in uneven distribution of carbides (a mixture of lamellar carbides and spherical carbides, and uneven carbides distribution). This degrades cold forgeability and promotes grain coarsening during carburizing. To address this problem, new SA methods combined with suitable chemical compositions are required to achieve a uniform distribution of carbides in a hypoeutectoid steel.