An Integrated Computational and Experimental Study of Vortex Chamber Performance for Reducing Entrapped Slag and Reoxidation Defects in Steel Castings

Slag defects remain a persisting and prominent problem for steel foundries across the world. Slag defects are surface defects usually caused by oxides transported from the pouring ladle or formed during the initial stages of filling that are transported into the casting cavity during pouring. This study investigates the use of vortex chambers as a component of the gating system and a potential slag trapping mechanism for ferrous metals through computational modeling and experimental validations. Six vortex chamber designs were studied using 3D sand-printing (3DSP) with varying chamber thickness and inlet-outlet height difference. For experimental validation, ASTM A216 WCB steel plates were cast using these vortex chamber designs. The results were compared to a benchmark design consisting of a conventional straight runner section in place of the vortex chamber. Computational results include ingate velocity during filling, entrained air volume fraction, and free surface defect mass. Experimental results include a subsurface pore volume fraction model based on the measured ultrasonic wave speed and attenuation. The experimental results were correlated with the computational results and show strong agreement. The computational results suggest a 31% reduction in melt velocity at the ingate from one of the vortex chamber designs and confirming the reduction in turbulence and reoxidation in the melt stream. However, the experimental results suggest no significant improvement in terms of subsurface porosity for the vortex chamber designs based on previous literature.