A novel technique for reducing macrosegregation in heavy steel ingots

Solid steel balls were added to the melt during the pouring process. A reference 500 kg steel ingot with no addition of solid balls was poured to provide a realistic comparison with the typical macrosegregation found in conventional industry heavy ingots. The experiments show that by adding solid balls the degree of macrosegregation is reduced, the formation of A-type segregation is prevented, a generally refined microstructure is obtained and the mechanical properties are improved. Numerical simulation of the solidification process confirms that the addition of solid balls increases the cooling rate, imposing large temperature gradient which refine the microstructure and alleviate the extent of macrosegregation.