Determination of Viscosity for Liquid Fe–Cr–Mn–Ni Alloys

The determination of viscosity of liquid Cr–Mn–Ni steel (16% Cr, 7% Mn) alloyed with 3–20% nickel is of interest in the present experimental investigation. The alloys are manufactured using a cold crucible induction levitation melting. The viscosity measurement is performed using a vibrating finger viscometer for high temperatures (≥1500 °C) and viscosities below 10 mPa s. The BN–ZrO2 vibrating finger is set in a driven harmonic oscillation in its resonance frequency of ca. 26 Hz. The constant peak-to-peak amplitude of the oscillator is controlled using a laser micrometer and a powered field coil. The viscosity of Fe–Cr–Mn–Ni alloys is slightly decreased from 3 to 6% nickel and from 6 to 9% nickel a slight increase of the isothermal viscosity is observed. Finally, the viscosity decreased significantly from 9 to 20% nickel content in the samples. The variation in the viscosity at high temperatures can be caused by a change in the primary solidification behavior, as shown in the phase diagram of the Cr–Mn–Ni steel. The temperature function of the viscosity of the high-alloyed steels is expressed using the Arrhenius function. A precise viscosity measurement is necessary for a mathematical modeling of the vacuum inert gas atomization of steel powder manufacturing.