Study on solid state steelmaking from thin cast iron sheets through decarburization in H2O–H2

Abstract

ABSTRACT To study the decarburization behavior of cast iron sheets, a series of gas-solid experiments were carried out. The treatment was carried out under Ar-H2-H2O mixed gas atmosphere. Results show that P H2O/P H2 in the gas mixture determines the oxidation of iron at a given temperature and the critical value of P H2O/P H2 to produce ferric oxide rises with temperature. The oxidation of iron take place when the ratio of P H2O/P H2 > 0.62, 0.66, 0.7 at 1293 K, 1353 K, 1413 K, respectively. The gas-solid decarburization reaction of cast iron sheets follows first-order kinetics. Cross-sectional microstructure images indicate that graphitization of cast iron sheets occurs at 1353 and 1413 K. The depth of the decarburized layer increases gradually with temperature and time, the square of depth has a near linear relationship with time. The activation energies of the decarburization reaction calculated by two different ways are similar to that for internal carbon diffusion.