Effects of ultrasound on the flow field in molten steel and solidification structure

Abstract

This research was based on FLUENT (a Computational Fluid Dynamics software). The handling process of molten steel with ultrasonic treatment was simulated by inserting volume force into the Navier–Stokes (N-S) momentum equation, and volume force was calculated through programming a User-defined Function. Accordingly, with ultrasonic treatment at constant temperature (1843 K), the flow of liquid steel was driven by a main whirlpool and its maximum velocity was 0.259 m s−1, conforming to the data in previous literature. The best characteristic insertion depth was 0.056. Moreover, conditions of other virtual force were calculated. The coupling phenomenon between the temperature field and the flow field was explained. The corresponding contrast test was carried out. Some simulation results were proved by the contrast test. The porosity of steel with ultrasonic treatment was reduced when held at 1843 K. With ultrasonic treatment, the equiaxed crystal ratio of steel increased, its grain was refined and its porosity was reduced more obviously during the initial stage of solidification.