Longitudinal cracks at the corners may be located near the edge of the junction between the wide face and the narrow face, some are 10 to 15 mm away from the edge, and some are just on the edge, which may cause steel breakout in severe cases. Reasons for formation: For a square shape, it may be that the thickness of the water gap along the height of the mold is not uniform, resulting in poor cooling of the corner of the mold; the taper of the mold is too small, and the radius of the mold fillet is too small. For slabs, it may be due to (1) improper support of the narrow surface causing the narrow surface to bulge. The bulging belly with a narrow face of 6-12mm is accompanied by longitudinal cracks at the corners, resulting in steel breakout.
(2) The taper is not suitable.
(3) Insufficient cooling water on the narrow surface.
ways to improve:
for billet
1) Control the geometry of the mold to prevent deformation.
2) Appropriate corner radius.
3) When assembling the mold, keep the thickness of the cooling water seam consistent to make the cooling even.
for slabs
1) Adjust the gap between the narrow surface foot rollers to limit the bulging inward by l～2mm.
2) Appropriate taper (1.0%/m).
3) Appropriate amount of cooling water.
4) Do not deviate from the center of the nozzle and the mold.
