Abstract
The results of an experimental study of the temperature dependences of the kinematic viscosity and specific electrical resistance of wear-resistant cast irons ИЧХ28Н2 and ICh300Kh25F4 in the liquid state are presented. The kinematic viscosity was determined by the method of damped torsional oscillations of a crucible with a melt. Specific electrical resistance was measured by the rotating magnetic field method. The measurements were carried out in the mode of two successive heatings of the samples from 1300 to 1650°C. After the first measurement, the sample was crystallized and cooled to a temperature of 25 °C at a rate of 1 °C/s. The second measurement was carried out without removing the sample from the laboratory setup and changing the atmosphere. The results of measuring the temperature dependences of kinematic viscosity and specific electrical resistance are discussed in the context of the concept of the microheterogeneous structure of liquid cast irons. Hysteresis of the temperature dependences of viscosity and electrical resistance obtained during the first heating of the samples to 1550°С was detected, which serves as indirect evidence of the destruction of microheterogeneities. The absence of hysteresis during the second heating of the sample after crystallization confirms the irreversible nature of the destruction of microheterogeneities. A conclusion is made on the recommended mode of high-temperature melt treatment (HTMT) of wear-resistant cast irons, which involves heating the melt to 1550°С. Heating of liquid wear-resistant cast irons IChKh28N2 and ICh300Kh25F4 to 1550°С leads to the destruction of micro-inhomogeneities, as a result of which, upon subsequent cooling and crystallization, an improved microstructure of the ingot is formed.