Numerical Simulation and Experimental Validation on the Effect of Stirring Coils' Parameters on TC17 Ingot During Vacuum Arc Remelting Process

Abstract:

To reduce the risk of β-flecks, the impact of stirring coils' parameters on ingot composition and grain structure was evaluated in TC17 alloys. A model coupling the temperature, electromagnetic, fluid flow, and the solute field was established using MeltFlow vacuum arc remelting (VAR) software. The results show that Cr concentration at the centre increases gradually from the bottom and then increases sharply within 100 mm to the ingot top, showing unlike tendency compared with locations at the edge and 1/2 diameter of the ingot. The increase in either the stirring coil current or reversal time is beneficial to the decrease in Cr content and the width of equiaxed crystal at the ingot centre, due to the accelerated turbulent velocity, which causes additional mixing within the molten pool. From the macromorphology observations of TC17 ingot, at near half of the lower part of the ingot, the location where the disturbance occurs in the direction of columnar crystal growth is corresponding to the position where Cr content increases, both of which have a relationship with stirring coil parameters. The simulation results fit the experimental data well.