Decomposition of phase-hardened martensite in Fe-Ni-C alloy

The processes that take place during tempering of the martensite of quenched steel are essentially governed by the chemical composition of the steel and the various influences to which it is exposed. Systematic investigations have been made to observe the effect of the content of carbon and alloying elements in the [alpha]-solid solution, elastic and plastic deformation, and irradiation by high-energy particles, and other factors influencing the mechanism and kinetics of martensite decomposition. The influence of phase hardening, caused by [delta] [r reversible] [alpha] transitions, on martensite decomposition needs further study. It has been shown that when quenched, Fe-Ni steel, is heated in the range of the reverse [alpha] [r arrow] [delta] transition at a rate 60 K/s, the effect of phase hardening reduces to a rise in intensity of martensite decomposition without any change in its mechanism. In the present work the authors have investigated the influence of phase hardening on the decomposition of martensite in an alloy in which the transition is accomplished by the shear mechanism, involving diffusion redistribution of the alloying elements between [alpha]- and [delta]-phases.