Abstract
The changes of viscosity in molten metals were measured in neutral or vacuum atmospheres and then, these values were found unrelated with runnability. But this was clearly unreasonable, because metals melted in air absorb a few gases and the viscosity of metals containing these gases should be measured in relation with runnability. The flowing down method was adopted by the author in this report and a few remarkable results were obtained as follows. (1) The viscosities of molten metals in neutral atmosphere proved to show a large differences from the viscosities measured in air and the former showed a decreasing inclination with increasing temperature and the latter an increasing inclination. Near the upper ranges of melting point, the viscosities measured in air indicated lower values than in neutral. (2) The effects of max. heating temperature for viscosities by melting in air gave a remarkable change and the pec liar values were given at every temperature and the effects of different specimens were recognized. (3) Similarly, the effects of holding time at every temperature were conspicuously recognized and in both specimens, a large increase of viscosity was given by 60 min holding. (4) The changes of viscosity by melting in air indicated the perfect reciprocal relation with the results of runnability measured in the same conditions, and it was clarified that the change of runnability was essentially under the control of the change of viscosity in liquid metal based on the gas absorption by melting in air.
