Dependence of precipitate formation on normalizing temperature and its impact on the heat treatment of F82H-BA07 Steel

A detailed study of the microstructural evolution during heat treatment of F82H steel at different temperatures has been carried out. By increasing the normalizing temperature from 1193 K to 1333 K, the residual austenitic and packet grain sizes increased. The chromium-enriched precipitate, M23C6, increased with the normalizing temperature. Tiny vanadium-rich precipitates, of the MX type, were formed on the grain boundaries when the normalizing temperature remained below 1223 K. Above 1223 K, the proportion of vanadium-enriched precipitate decreased significantly. With a two-step normalizing heat treatment, tiny tantalum- and vanadium-rich precipitates remained on the grain boundaries and within grains when the normalizing temperature of the second step remained below 1223 K. It suggested that the second-step heat treatment in a two-step normalizing heat treatment above 1223 K influenced the tantalum- and vanadium-rich MX precipitate formation in F82H steel.