微合金钢连铸方坯表面裂纹成因分析及控制  

Analysis and control of surface cracks on casting bloom of microalloyed steel

作　　者：曾亚南[1] 孙彦辉[1] 艾西[1] 马志飞[1] 刘瑞宁 刘泳 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]河北钢铁集团石家庄钢铁有限责任公司,河北石家庄050031

出　　处：《炼钢》2014年第4期15-19,共5页Steelmaking

摘　　要：针对某厂生产微合金钢大方坯产生大量表面缺陷的状况，对铸坯生产过程的工艺参数进行了统计分析，利用Gleeble-l500热模拟试验机研究了钢种的热塑性，同时利用金相显微镜、SEM、TEM对缺陷铸坯的微观组织和析出粒子等进行了分析研究，结果表明：铸坯在矫直区产生17-25μm的铁素体膜，产生应力集中。裂纹处残余铜含量偏高，诱发裂纹生成延伸。拉速由0．58m／min提升至0．63m／min时，铸坯在矫直区温度平均提高40℃左右。控制钢水叫（N）在45×10-6左右，结晶器保护渣碱度在1．11，黏度为0．85Pa·s，液渣层厚度在8mm以上时，可以有效改善铸坯裂纹。Based on the conditions of defects of HSLA steel during solidification, the process parameters of continuous casting were analyzed. The surface cracks of bloom were investigated by optical microscopy, SEM and EDS, the precipitates were analyzed by TEM. Furthermore, the hot ductility was studied by Gleeble-1500 thermal simulator. The results showed that ferrite film, formed in straightening area, is in the range from 17-25μm, would lead to stress concentration at grain boundaries. Cracks would be induced by the higher content of copper. In addition, the surface temperature of bloom was improved 40 ℃ with the casting speed increasing from 0. 58 m/s to 0. 63 m/ min. In order to decrease the cracks during continuous casting, the mass fraction of nitrogen in steel should be controlled in 45 × 10-6, the basicity of mold powder and viscosity should be controlled at 1.11, 0. 85 Pa·s, and the molten slag layer should greater than 8 mm.

关 键 词：微合金钢 大方坯 表面缺陷 脆性区 析出粒子 

分 类 号：TF777.2[冶金工程—钢铁冶金]