高拉速HRB500VNb方坯角部裂纹分析与控制  

ANALYSIS AND OPTIMIZATION OF CORNER CRACKOF HRB500VNb BILLET AT HIGH DRAWING SPEED

作　　者：张垚 柳晓辉 张万庆 李超[1] 张福利 Zhang Yao;Liu Xiaohui;Zhang Wanqing;Li Chao;Zhang Fuli(Tangshan Iron and Steel Group Co.,Ltd.,Tangshan 063016,Hebei)

机构地区：[1]唐山钢铁集团有限责任公司,河北唐山063016

出　　处：《河北冶金》2024年第12期63-67,74,共6页Hebei Metallurgy

摘　　要：通过对河钢集团唐钢公司长材事业部生产的HRB500VNb方坯与HRB500方坯的低倍组织对比,结合HRB500VNb铸坯角部温度场数值模拟,分析了铸坯角部裂纹产生的原因。结果表明,HRB500VNb发生2.0级以上的角部裂纹的几率明显高于HRB500。通过将结晶器水量由160 t·h^(-1)降低到130 t·h^(-1),水流速由12.46 m/s降低到10.34 m/s,结晶器角部半径由8 mm提高到10 mm,弱化铸坯角部传热;优化保护渣物化参数,降低保护渣粘度、熔点、碱度,提高熔速,改善铸坯与结晶器之间的传热;将二冷一区的水量降低8%,二冷三区水量增加6%,整体比水量降低0.2 L/kg,减缓铸坯的冷却速度;采用低硫、磷铁水与优质废钢,转炉出钢成分确保w(P)≤0.037%、w(S)≤0.028%,以减少夹杂物引起的角裂;炼钢工序进行全流程控氮,使氮含量控制在115~150 ppm,工艺优化后HRB500VNb方坯的角部裂纹最大等级为3级,角部裂纹2.5级及以上的比例由53.62%降低至16.09%,铸坯质量明显改善。By comparing the low magnification structure of HRB500VNb billets produced by the Long Materials Division of HBIS Group Tangsteel with HRB500 billets,and combining with numerical simulation of the temperature field at the corners of HRB500VNb billets,the causes of corner cracks in the billets were analyzed.The results indicate that the probability of HRB500VNb experiencing corner cracks above 2.0 level is significantly higher than that of HRB500.By reducing the water volume of the mold from 160 t·h^(-1) to 130 t·h^(-1),the water flow rate from 12.46 m/s to 10.34 m/s,and the radius of the mold corner from 8 mm to 10 mm,the heat transfer in the corner of the casting billet is weakened.Optimize the physicochemical parameters of the mold powder,reduce the viscosity,melting point and alkalinity of the protective slag,increase the melting rate,and improve the heat transfer between the casting billet and the mold.The water in the first zone of the second cooling is reduced by 8%,the water in the third zone of the second cooling is increased by 6%,the overall specific water is reduced by 0.2 L/kg,and the cooling speed of the casting billet is slowed down.Using low sulfur,phosphorus hot metal and high-quality scrap steel,the steel composition of converter should ensure w(P)not more than 0.037%,w(S)not more than 0.028%to reduce the Angle crack caused by inclusions;After the process optimization,the maximum level of corner crack of HRB500VNb billet is 3,and the proportion of corner crack of 2.5 or above is reduced from 53.62%to 16.09%,and the quality of billet is obviously improved.

关 键 词：HRB500VNb 高拉速 方坯 角部裂纹 磷 氮 保护渣 

分 类 号：TF55[冶金工程—钢铁冶金]