A kinetic theory of martensite formation is developed for the case when isothermal transformation does not complete, which is conventionally explained in terms of the change in the state of $\gamma$ phase. The closest agreement with experiment is obtained when the Kaufman-Cohen theory modifie by Borgenstam and Hillert is used for the nucleation rate

D.A. Mirzayev

I.L. Yakovleva

K.Yu. Okishev

S.Ye. Karzunov