大型钢锭轧板开裂和穿孔缺陷分析及浇铸工艺优化

Analysis on Cracking and Perforation Defects of Heavy Plate Rolled from Large-Scale Ingot and Optimization of Casting Process

分析了S355JR和S355J2低碳钢(/%:0.17～0.20C、0.30～0.55Si、1.40～1.60Mn、≤0.020P、≤0.015S、0.020～0.040A1、0.020～0.030Nb)28～40 t钢锭轧成230～400 mm钢板出现的开裂和穿孔缺陷。通过提高浇钢工操作水平,根据钢水过热度控制本体浇铸和帽口浇铸时问;控制精炼终点[O]≤25×10^(-6)以及钢中铝含量0.020%～0.040%等优化浇铸工艺措施使钢锭探伤合格率提高到96.8%。

An analysis on cracking and perforation defects occurred in 230 ~ 400 mm plates rolled from 28 ~ 40 t ingot of low carbon steel S355JR and S355J2 （/% ： 0. 17 ~ 0. 20C, 0. 30 ~0. 55Si, 1.40 ~ 1.60Mn, ≤0. 020P, ≤0. 015S, 0. 020 ~0. 040A1, 0. 020~0. 030Nb） is emTied out. With the optimum process measures including increasing level of op- eration crews, controlling ingot body and hot top casting speed according to overheating extent of liquid, controlling refining end [O]≤25 ×10^-6 and aluminium content in steel 0. 020%~0. 040% , the ingot qualified ratio by nondestructive testing increases to 96.8%.