# Influence of Secondary Electromagnetic Stirring and Soft Reduction on Slab Macrosegregation Evolution of E355 Steel

## TL;DR

This study shows how electromagnetic stirring and soft reduction can reduce defects in steel slabs, improving the quality of rolled steel products.

## Contribution

The paper introduces optimized parameters for secondary electromagnetic stirring and soft reduction to minimize macrosegregation in E355 steel slabs.

## Key findings

- Increasing electromagnetic stirring intensity improves equiaxed crystal ratio and reduces centerline segregation.
- Alternating stirring mode is more effective than continuous mode in reducing segregation.
- Optimized parameters reduced banded structures and improved mechanical property consistency in rolled plates.

## Abstract

Macrosegregation in continuous casting slabs remains a critical defect that adversely affects the homogeneity and mechanical properties of the final rolled products. Industrial experiments were conducted on E355 steel continuous casting slabs to investigate the effects of electromagnetic stirring (EMS) and soft reduction (SR) on the evolution of slab macrosegregation. Furthermore, the inheritance of segregation from the slab to the rolled plate was analyzed. The results indicate that the equiaxed crystal ratio increases and the centerline segregation decreases with increasing stirring intensity. The application of both secondary EMS and SR minimized the centerline segregation in the slab. When the current intensity was increased from 0 A to 320 A in continuous stirring mode, the equiaxed crystal fraction increased from 22.52% to 32.52%, and the centerline segregation index decreased from 1.23 to 1.17. Compared with the continuous stirring mode, the alternating stirring mode promoted a more pronounced increase in the equiaxed crystal ratio and a further reduction in the centerline segregation. The centerline segregation in the slab correlates with the banded structure observed in the rolled plate. A higher degree of slab centerline segregation corresponds to a more severe banded structure and greater fluctuations in the mechanical properties of the plate. Through parameter optimization, the recommended settings are an alternating stirring mode with a current of 320 A at 5 Hz and an SR amount of 3 mm. Under these optimized conditions, the equiaxed crystal ratio of the slab increased to 35.22%, the centerline segregation index dropped to 1.15, and the banded structure in the rolled plate was reduced to grade 2.0. Consequently, the standard deviations of the tensile strength and elongation were 8.03 MPa and 1.1%, respectively.