METHOD OF ESTIMATING GENERATION OF CENTRAL CRACK IN CONTINUOUS CASTING

摘要

PURPOSE:To make adequate processing and to prevent the central crack by deciding the generation of the entrapment of an unsolidified molten steel and predicting the generation of the central trap when the entrapment quantity of the unsolidified molten steel exceeds the permissible limit quantity. CONSTITUTION:The generation of the entrapment of the unsolidified molten steel is decided when the time difference tf1 from the measurement time detected at a set period T by a measuring instrument before the complete solidification based on the measured time and the time difference tf2 of the next time measurement satisfies equation I at the time of estimating the complete solidification position of an ingot from the measured value by the shell thickness measuring instrument or ingot section temp. measuring instrument installed to a machine end part. The entrapment quantity of the unsolidified molten steel is calculated by equation II. In equation, Q: the entrapment quantity of the unsolidified molten steel; (n): the number of the times when the decision of the entrapment is continuously generated; tf1: the time difference before the complete solidification at the measurement time, tfi+n: the time difference before the measurement time when the tf1 at the generation of the entrapment decision of the unsolidified molten steel continuously (n) times is obtd. before the complete solidification after TXn; Vc: the casting speed, T: measurement period. The generation of the central crack is decided when the entrapment quantity exceeds the permissible limit quantity.