SWRCH10A包晶钢轧后结疤裂纹成因分析及控制技术

Cause analysis and control technology of scab cracks for rolled SWRCH10A peritectic steel

针对邢台钢铁有限责任公司生产的SWRCH10A包晶钢160 mm×160 mm规格连铸坯在轧制成Φ11 mm规格线材后,在成品线材表面发现结疤裂纹的问题,采用光学显微镜及扫描电镜对裂纹情况进行检测和分析。检验结果显示:结疤显微裂纹两侧存在明显的脱碳现象,裂纹内部为氧化铁皮。同时,经低倍酸洗发现铸坯表面存在明显的宏观表面裂纹,判断成品线材结疤裂纹为铸坯表面裂纹缺陷经轧制变形后遗留导致的。结合实际生产情况,通过调整连铸机结晶器冷却水流量、降低连铸拉速,以及控制成品的碳含量及氮铝浓度积等一系列措施,改善铸坯外观质量,最终有效消除了成品线材表面结疤裂纹问题。

For the problem of scab cracks on the surface of finished wire rod after the 160 mm×160 mm continuous casting billet was rolled to the Φ11 mm wire rod for SWRCH10A peritectic steel produced by Xingtai Iron & Steel Co.,Ltd.,the cracks were detected and analyzed by optical microscope and scanning electron microscope.The test results show that there is obvious decarburization on the both sides of scab microscopic crack,and there is iron oxide scale inside the crack.At the same time,obvious macroscopic surface cracks are found on the surface of cast billet after low magnification pickling,and the scab cracks on the finished wire rod are caused by the remaining surface crack defects of cast billet after rolling deformation.According to the actual production situation,a series of measures are conducted to improve the appearance quality of cast billet by adjusting the cooling water flow of continuous casting machine crystallizer,reducing the drawing speed of continuous casting,and controlling the carbon content and the concentration of nitrogen and aluminum for the finished product,and finally the problem of scab cracks on the surface of wire rod is effectively eliminated.