Causes of Corner Cracks in Hypoperitectic Microalloyed Steel Billets

Abstract

Due to the development of continuous casting technology, the incidence of cracks in the continuous casting process has been significantly reduced. However, a few small cracks still appear during the continuous casting of special steel. For instance, cracks often appear at the corner of the billet during the production of hypoperitectic microalloyed steel. Most research on the causes of corner cracks in hypoperitectic microalloyed steel has focused on investigating the hot ductility of steel and not considered the shrinkage characteristics during solidification. Herein, the hot ductility behavior show that cracks are not related to the hot brittleness of steel. The effects of alloy composition on the phase evolution and shrinkage of steel during solidification are focused. Uneven solidification leads to excessive shrinkage of the corners in the billet, and an air gap is generated between the billet and the mold. The return of temperature in the corner of the billet results in the coarseness of the corner grain. Abnormal solidification also results in the severe deformation of the billet, leading to severe wear with the mold, causing Cu to infiltrate into the billet, and further increasing the crack sensitivity of the steel.