抄録
When titanium (zirconium or vanadium), nitrogen and carbon are contained in steel, nitride and (or) carbide of the element are formed according to the degree of stability of these compounds. The free energy equations of the formation of nitrides and carbides in steel are derived by the same method described in the previous report (Tetsu to Hagane (1955) vol. 41, No. 10, p. 1082). The equilibrium relations of the formation of titanium-, zirconium- and vanadium-nitrides and carbides are calculated by these equations in several cases of different contents of these elements. According to the results of calculation, both titanium-(zirconium-) nitride and carbide are estimated to be effective as grain growth inhibitors, but inclusions which are precipitated in austenite may be considered to be more effective as inhibitors than those in molten steel. Vanadium nitride may also be effective as the inhibitor but there remains some uncertainty. Vanadium carbide 'VC' does not precipitate in steel while 'V4C3' may precipitate in austenite and may be effective as the inhibitor.
