FACTORS CONTROLLING THE GRAPHITIZATION OF HIGH CARBON STEEL AT SUBCRITICAL TEMPERATURE (Part-1)

Study on the graphitization of high carbon steel-I

Abstract

Several experiments has been made in an effort to reveal some of the factors controlling graphitization of pure high carbon steel deoxidized with aluminum and silicon. The results obtained were as follows:
(1) Rate of dissociation of cementite was a maximum at about 650°C.
(2) The reaction rate of dissociation of cementite was a maximum when the steel had been quenched previously in order to produce martensite, and less graphite formed in the furnace cooled, air cooled or isothermal transformed samples.
(3) The heating at 1000°C for 2 hours and furnace cooling after water-quenching from 870°C inhibited very markedly the graphitization on subsequent anneal at 650°C. The treatment of heating above the critical apparently tend to destroy or render inoperative nucleation which would promote graphitization.
(4) Cold drawing accelerated the formation of the graphite nuclei and the increase in the cold reduction to 50% produced a corresponding increase in the rate of graphitization.
(5) The more graphite fromed in cold drawn samples of pearlitic structure than spheroidized state on subsequent annealing at 650°C.