Influence of Scale Formation on Copper Enrichment Behaviour in Continuously Cast Slab

Copper enrichment behavior in continuously cast slab induced by scale formation after continuous cooling in H₂O vapor atmosphere and consecutively in air has been experimentally investigated by combining with SEM-EDS analysis, for the purpose to examine the effects of initial slab surface temperature and contents of copper and nickel. For Slab 1 with copper content of 0.1 percent, no visible copper enrichment is found at scale-substrate interface irrespective of the various scale microstructures formed at different initial slab surface temperatures. For Slab 2 with higher contents of copper and nickel, copper-rich phase accumulates and stays at scale-substrate interface under the condition of lower initial slab surface temperature; while Cu-rich phase in the porous scale formed at higher initial slab surface temperature is noted with simultaneous Ni-emichment appearing in front of the steel-scale interface. Both a porous scale and high nickel content work together to provide pores for copper-rich phase migration away from interface and occlude within the scale layer.