MasazOkamoto and Yukimasa Ozawa
(1) The hyper-eutectoid steel is more difficult to deacarburize than the eutectoid steel in spite of its higher carbon content probably because of the finer austenitic grain size in the former. (2) When special element is added in steel, the decarburization is reduced in proportion to the intensity of the affinity between carbon and the special element. Ni has a weak affinity for carbon,but it retards the decarburization a little for it refines somewhat the austenitic grain size. Mn coarsens the austenitic grain size, but it retards the decarburization probably because of the affinity for carbon.Cr makes the decarburization very difficult, for it has a strong affinity for carbon and also refines strongly the austenitic grain size. (3) On the prevention of oxidation the packing materials give the best result in CaO powder followed by MgO, Al2O3, SiO2 and then Fe2O3. Especially, when CaO is used the surface of the steel has not yet lost the metallic lustre even after heated at 1000° for 2 hours. Furthermore the decarburization of steel is strongly promoted by using CaO. Hence, it is very effective for non-oxidation decarburization. (4) Both the intensity of the affinity of W for carbon and that of the action of W to refine the austenitic grain size are almost equal to those of Cr, notwithstanding W has for weaker action to retard the decarburization than Cr. It is probably because in the same weight percentage the number of W atom is far fewer than that of Cr atom.
Please do not copy without permission.