Study on the Dendrite Arm Spacing of S50C Steel Produced by CSP

The as-cast structure always plays an important role in the formation of macrosegregation in steel products. In this study, the dendrite arm spacing of S50C steel in different positions on the slab produced without electromagnetic stirring by compact strip production) (CSP) was measured through the morphology obtained by LEXT OLS4100 laser scanning confocal microscope. The results show that: (1) the as-cast structure consisted of three zones: columnar zone, columnar to equiaxed transition (CET) zone, and equiaxed zone, among which the percentage of the equiaxed zone is about 12–13% and the CET zone is about 16%; (2) the range of λ₁ for the primary dendrite arm spacing (PDAS) is 100–220 μm and that of λ₂ for the secondary arm spacing (SDAS) is 60–120 μm, both of which show an increasing trend from the surface to the center of the slab; (3) the dendrite arms become coarsened from surface to the center of the slab; and (4) the cooling rate (ε) and permeability (K_P) were calculated and the trend of ε decreases from surface to center of the slab, and the trend of K_P increases, which means heavy segregation in the center of the slab.