A greater mitigation effect of single-coil helical electromagnetic stirring on central carbon segregation of 45 steel continuous casting billet

A novel single-coil helical electromagnetic stirring (SHEMS) is proposed to relieve central carbon segregation and shrinkage in 45 steel continuous casting billets. Simulations and industrial trials on 180 mm × 180 mm billets are conducted to compare SHEMS with rotary electromagnetic stirring (REMS). The REMS only generates circumferential flow with weak temperature homogenisation, while SHEMS forms three-dimensional helical flow with axial components to lower the core-surface temperature gradient. Besides, industrial trials demonstrate that SHEMS raises the equiaxed ratio from 18% to 21% and reduces average shrinkage cavity size. Moreover, compared with no‑EMS, REMS relieves segregation by only 3.5%, whereas SHEMS achieves a 23.7% reduction in segregation. This study verifies that the SHEMS can be an outstanding strategy for continuous casting billets to optimise solidification microstructure, central shrinkage and carbon segregation.