连铸结晶器水量对40Cr钢方坯表面裂纹的影响  

Effect of mold water flow rate in 40Cr billet continuous casting on surface crack

作　　者：史伟宁 SHI Wei-ning(Steelmaking Plant,Xiangtan Iron and Steel Group Co.,Ltd.,Xiangtan 411101,Hunan,China)

机构地区：[1]湘潭钢铁集团有限公司炼钢厂,湖南湘潭411101

出　　处：《连铸》2023年第2期84-89,105,共7页Continuous Casting

摘　　要：为了改善湘钢2号连铸机产出的40Cr钢铸坯表面裂纹问题,特对不同结晶器水量下铸坯表面质量的变化进行研究。结果表明,随着结晶器水量增加,热流密度先增加后降低,铸坯表层的晶粒尺寸先减小后增大。当结晶器水量小于2250 L/min时,铸坯表层存在数量较多的异常长大奥氏体晶粒组织,晶粒度不均匀,铸坯表层裂纹主要沿着晶界扩展。当结晶器水量大于2333.33 L/min时,随着结晶器水量增加,热流密度降低,铸坯表层晶粒尺寸开始增加,铸坯表层没有出现裂纹。当结晶器水量为2333.33 L/min时,靠近结晶器壁侧钢水形核率最大,铸坯表层晶粒度最细小均匀,获得了最有利于抵抗应力开裂的晶粒组织。这种分析方法为解决铸坯表面裂纹问题提供了新思路。In order to improve the surface cracks of 40Cr steel billet produced by Xianggang’s No.2 continuous casting machine,the evolution of surface quality of the billet under different mold water flow rates was studied.The results show that with the increase of the mold water flow rate,the heat flux density increases first and then decreases,and the grain size on the billet surface decreases first and then increases.When the mold water flow rate is less than 2250 L/min,a large number of abnormally grown austenite grain structures are displayed and the grain sizes are not uniform on the billet surface,the surface cracks of the billet mainly propagate along the grain boundaries.When the mold water flow rate is greater than 2333.33 L/min,with the increase of the mold water flow rate,the heat flux density decreases,the grain sizes on the billet surface increase again,but surface cracks on the billet disappear.When the mold water flow rate is 2333.33 L/min,the nucleation rate of molten steel near the mold wall is the largest,the grain size of the billet surface is the smallest and uniform,and the grain structure that is the most conducive to resisting stress cracking is obtained.This analysis method provides a new idea for solving the problem of billet surface cracks.

关 键 词：方坯连铸 结晶器水量 表面裂纹 晶粒尺寸 形核率 

分 类 号：TF777[冶金工程—钢铁冶金]