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.

Formation Mechanism and Control Technology of Transverse Corner Cracks During Slab Continuous Casting of Microalloyed Steels

“…Therefore, there are different understandings of the location for the formation of corner transverse cracks in microalloyed steel slabs. Many previous studies [2][3][4][5][6][7] considered that transverse corner cracks were mainly affected by improper oscillation and mold flux as well as evident fluctuation of mold level. When the friction force and thermal stress are larger than the threshold of steel, transverse corner cracks would occur at the troughs of oscillation marks.…”

Formation and Deformation Mechanism of Mountain‐Like Surface Crack on the Hot‐Rolled Thick Plate of HSLA Steel

“…Before rolling, the microcrack is in an upright V-shape. [11,21] As the slab moves to the left, the side-1 of the microcrack is the first to come into contact with the roll and deforms in the RD direction. Subsequently, the side-2 of the microcrack also comes into contact with the roll and deforms in the RD direction.…”

“…These cracks are large in size and simple in morphology and can be seen directly and clearly without treatment of the plate surface. [7][8][9][10][11][12] Sarkar et al studied the causes of corner defects and longitudinal cracks in the hotrolled plate of C-Mn steel. [7] The article concluded that the surface cracks in the hot-rolled plate were due to surface defects in the continuous casting slab by observing the morphology of the crack and the inclusions inside the cracks.…”

Effects of Sulfur on the Surface Crack in Medium Carbon Bloom

“…[20,21] Hanao et al studied cracks caused by uneven solidification in the mold [22] and Xing et al studied cracks caused by additional mechanical stress due to mold wear. [23,24] Therefore, crack formation is a highly complex phenomenon worth investigating.…”