小方坯表面角部横裂纹对大规格螺纹钢筋表面质量的影响  

The Effect of Surface Transversal Corner Crack of Billet on the Surface Quality of Large-size Ribbed Bars

作　　者：孙彪[1,2] 刘学华[1,2] 陈开智[1] 付振宇[1] 赵志海[1,2] 杨丽珠[1,2] 

机构地区：[1]马鞍山钢铁股份有限公司 [2]高性能轨道交通新材料及安全控制安徽省重点实验室

出　　处：《安徽冶金》2015年第2期13-17,共5页Anhui Metallurgy

摘　　要：某厂生产的Φ40mm热轧螺纹钢筋表面常有细小的线状缺陷,作为其原料的小方坯表面也发现有表面角部横裂纹。为考察小方坯表面角部横裂纹在螺纹钢筋表面形成何种缺陷及缺陷的形貌,对预制有不同深度、宽度表面角部横裂纹的小方坯进行了工业性轧制试验,样坯轧成Φ40mm的螺纹钢筋后,采用酸洗、金相等方法对其进行检验分析。结果表明:方坯表面的角部横裂纹在螺纹钢筋表面形成与轧制方向呈一定角度的线状缺陷,且随着裂纹深度、长度变小,螺纹钢筋上的线状裂纹深度变浅。为查找小方坯表面角部横裂纹的形成原因,采用非接触式高精度红外温度传感器测温系统对典型连铸工况下小方坯角部温度进行了长时间的在线测量,发现小方坯角部温度偏低,据此,通过提高拉速、降低二冷水量、提高校弧精度、增加喷嘴检查的频次等措施,小方坯表面角部横裂纹明显减少,螺纹钢筋上的线状缺陷消失。Fine line defects on the Φ40mm hot rolled ribbed bar frequently occurred in MaSteel and at the same time surface transversal corner cracks were also found on its raw material billets.In order to probe the relationship between the fine line defects on the Φ40mm hot rolled ribbed bar and the surface transversal corner cracks on billets,industrial rolling experiments were carried out for billets with prefabricated surface corner cracks in different depth,width and length.The billets were hot rolled into Φ40mm ribbed bars and then inspected with acid macro-etching and metallographic techniques.The results showed that line defects with certain angle to rolling direction were evolved from the prefabricated surface corner cracks,and the depth of the line defects on the bars reduced with decrease of the depth and length of the prefabricated surface corner cracks on the billets.To find the reasons of formation of the surface transversal corner cracks,long-term online temperature measurement of the billet corners under typical casting conditions were performed with high-precision non-contact infrared sensor temperature measurement system,indicating that the temperature at the billet corners were not high enough.Based on these results,preventive measures such as increasing casting speed,reducing secondary cooling water consumption,increasing arc calibration precision and the frequency of nozzle inspection were taken,which have significantly reduced the surface transversal corner cracks on the billets and eliminated fine line defects on the Φ40mm hot rolled ribbed bars.

关 键 词：小方坯 表面角横裂 钢筋表面质量 措施 

分 类 号：TG142[一般工业技术—材料科学与工程]