基于二冷区凝固冷却的连铸大方坯表面裂纹控制研究OA

Severe surface cracks were observed on continuous casting blooms produced at a steel plant.Distinct decarburized layers on both sides of the cracks indicated that the cracks formed during the continuous casting process.The ductility temperature range of this steel grade was determined to be 985～1 290℃ via Gleeble high-temperature tensile testing.Fracture surface morphologies within this range exhibited numerous dimples of varying depths,characteristic of ductile fracture.Based on these findings,an optimization scheme for secondary cooling water distribution was proposed.The scheme included increasing the water flow rates in the second and third cooling zones to 1.3 times their original values,controlling the straightening point temperature within the ductility range of 985～1290℃,andlimitingthetemperaturereboundineachzoneto≤100℃/m.Industrial trial results demonstrated that after optimization,surface cracks on the blooms were essentially eliminated,and the first-pass yield for the surface inspection of the rolled products increased from78.2％to85.6％.