熔銑の改良研究(II)

Abstract

The changes in some properties of cast iron treated by blowing of various gases (N2, coke gas, H2, air, CO2 and O2) into the molten state were investigated.(1) By the blowing of reducing gases such as H2 and coke gas, the fluidity of molten iron increased and the precipitation of flaky graphite was accelerated. The above mentioned phenomena were distinct in the B.F. iron containing of Ti, V and other impurities.(2) By the blowing of N2, air and CO2 gases into the B.F. iron, the fluidity decreased, but the changes in other properties of the iron were not nearly observed. On the other hand, in a charcoal iron the structure was changed into the non-uniform fracture with fine graphite and at the same time the fluidity and tensile strength decreased.(3) By the blowing of O2 into B.F. irons6), impurities such as Ti, V and etc. decreased, and moreover the mechanical properties were improved so as to show the character near to that of charcoal iron.(4) The cast iron made of charcoal iron was easily nodulized by magnesium treatment. after the blowing of H2 or coke gas, whereas that of B.F. irons containing the amount of impurities were more easily nodulized after the blowing of O2. Perhaps the reason of this phenomena was as follows: it had been known that oxygen and impurities such as Ti, As, V and etc. prevented the nodulizing of graphite by magnesium. By the blowing of O2 into B.F. irons containing the amount of impurities, some of the impurities decreased but the oxygen- content did not increased. On the other hand, as charcoal iron did not contain impurities, the deoxidation by reducing gases gave the good effect for nodulizing of graphite.