Flow Patterns in Mold for Preventing Longitudinal Cracks on Peritectic Steel Grades

摘要

Longitudinal cracks (LFC's) are formed by casting speed variations, too high or low superheat, casting wide, rapid mold width changes, improper water cooling, taper loss, irregular mold oscillation, improper mold powder selections, worn molds, overcooling in the upper spray zones, insufficient support below the mold and poor alignment between mold and sub mold support system. Longitudinal cracks are also formed in the mold if non-uniform cooling at the meniscus results in uneven distribution of mold powder. Without the proper lubrication direct contact of liquid steel to the mold wall at localized spots cause strong temperature gradients to develop additional thermal stresses to the solidifying steel shell. All these factors are more relevant in peritectic steel grades where a strong shrinkage of the steel shell is provided by the peritectic phase transformation.