Studies have been made of the effects of thermo-mechanical treatment variables on the recrystallization of austenite, the transformation of austenite and precipitation strengthening in C-Hn steel containing niobium, niobium plus vanadium, vanadium and vanadium plus nitrogen. The amounts of niobium and vanadium were varied across the stoichiometric ratio of H:C and H:N in order to investigate the effect of stoichiometric ratio on the precipitation strengthening.