Study on the Viscosity of Molten Iron

抄録

The viscosity of Fe–C–Si alloy (3.5%C, 1.20%Si) was measured by the oscillating crucible method to investigate the presence of hysteresis and the difference in viscosity between white and grey iron melts of the same chemical composition, and to clarify a problem on the heredity of cast iron whose properties after melting depend upon charge materials. The results obtained are summarized as follows: (1) Viscosity curves measured in the superheating process did not correspond with those in the cooling process over the temperature range of 1255° to 1480°C: a negative hysteresis was recognized as proposed by Turovskii. The higher the maximum heating temperature, the wider became the hysteresis. (2) In this temperature range the viscosity of grey cast iron was higher than that of white cast iron. (3) In case of holding the melt at 1342° and 1288°C, the change in viscosity coefficient with time decreased rapidly by 20 minutes of holding. Subsequently, the difference between the white iron and grey cast iron melts was clearly recognized, where the viscosity of the latter was higher than that of the former. (4) With increasing Si content up to 0.43%, the hysteresis was hardly recognized, but over 1.22% Si there appeared the negative hysteresis. In both superheating and cooling proceses the viscosity showed a maximum at 1.22 %Si and a minimum at 0.43 and 2.70 %Si, respectively.