Practice of PMO renovation for ø 250 mm round billet continuous casting machine

Aiming at the quality problems such as central shrinkage cavity and central carbon segregation existing in the casting process of the ø250 mm round billet continuous caster at Tianjin Rockcheck United Iron and Steel Group Co., Ltd., targeted technical transformation was carried out on the continuous caster by adopting the Pulsed Magneto-Oscillation (PMO) solidification homogenization technology. This paper briefly introduces the equipment assembly, technical transformation scheme of PMO technology, and analyzes the effects of PMO technical transformation on the effective diameter of the central equiaxed crystal zone, central shrinkage cavity rating, element segregation and other aspects of continuous casting billets through industrial test results. Production practice shows that after PMO technical transformation, the effective diameter of the central equiaxed crystal zone of the casting billet increases from 117 to 157 mm, with an average increase of 34%; the proportion of grade 0 central shrinkage cavity of the casting billet rises from 20% to 63.6%, with an average increase of 218%. Meanwhile, PMO technology can effectively reduce the segregation degree of solute elements in the center of continuous casting billets. On the premise of ensuring that the internal quality of the casting billets stably meets the standards, it significantly increases the continuous casting speed, realizing the coordinated optimization of product quality and production efficiency.