Study on macrostructure refinement of 12 wt-%Cr ferritic stainless steel slabs by TiN nucleation

摘要

During the continuous casting of ferritic stainless steel slabs, the low area ratio of the central equiaxed crystal zone and the coarse macrostructure can be a major problem. Heterogeneous nucleation by TiN nucleation was applied to refine the macrostructure of 12%Cr ferritic stainless steel slabs in industrial production. The experimental results indicated that the macrostructure was refined significantly by Ti additions. The central equiaxed crystal zone deviated from the central line of the slab and was very close to the lower side of the slabs. Simultaneously, a secondary columnar crystal transition was observed in the upper regions of slabs. It was concluded that the sedimentation of plentiful free crystals in the upper region of slabs resulted in the deviation of the equiaxed crystal zone from the centreline and the appearance of secondary columnar crystals.