Improving quality of ø 250 mm SWRH82B hard-wire steel continuous casting billets by PMO

Due to its high carbon content, SWRH82B high-carbon steel is significantly affected by selective crystallization and solute enrichment effects during the continuous casting of ø250 mm round billets, which easily leads to severe central carbon segregation and shrinkage cavity defects, and further induces wire breakage problems in subsequent drawing processes. To improve the quality of ø250 mm SWRH82B hard wire steel continuous casting billets, Pulsed Magneto-Oscillation (PMO) solidification structure homogenization technology was introduced into the continuous casting production line of Tianjin Rockcheck United Iron and Steel Group Co., Ltd., the effects of PMO on the solidification structure and central segregation of ø250 mm continuously cast SWRH82B steel were studied. The results show that after applying PMO, the central carbon segregation index of the billet cross-section decreased from 1.19 to 1.09, with a maximum reduction of more than 43%. The width of the equiaxed crystal zone of the billet increased from 13.1 cm to 15.4 cm, the equiaxed grain ratio increased from 27.4% to 37.9%, the maximum value of the secondary dendrite arm spacing decreased from 185.9 μm to 159.9 μm, and the solidification structure was significantly refined.