Longitudinal Surface Cracks of Medium Carbon Steel on CSP Thin Slab

摘要

Since solidifying shell suffered much larger stress and strain than conventional slab in mold, thin slab is more sensitive to cracks. The longitudinal surface cracks of thin slab mainly appeared in the center and 1/4 regions of broad face which is corresponding to the position that center and border of the funnel. Based on the production practice of medium carbon steel thin slab by CSP plant, reasons and influential factors of longitudinal cracks were investigated, some industrial measures were adopted to eliminate the cracks. The efficient solution to reduce the longitudinal cracks are using of High CaO/SiO2 ratio, proper viscosity mold powder, maintain the stability of heat flux in mold and a proper taper during casting. Proper pouring temperature and secondary cooling, good running conditions (such as alignment between mold and submold surport assemblies, etc) also play an important role in prevention of longitudinal surface cracks.