连铸圆坯表面网状裂纹特征分析与控制  

Analysis and control of reticular crack on the surface of continuous casting round billet

作　　者：金友林[1] 汪国才[1] 陆强[1] JIN Youlin;WANG Guocai;LU Qiang(Special Steel Plant,Ma'anshan Iron and Steel Co.Ltd.,Ma'anshan 243002,China)

机构地区：[1]马鞍山钢铁股份有限公司特钢公司,安徽马鞍山243002

出　　处：《炼钢》2022年第3期43-47,共5页Steelmaking

摘　　要：采用酸浸低倍检测、电子显微镜、电子探针等手段对圆坯表面网状裂纹特征和形成原因进行了分析。研究发现圆坯表面网状裂纹沿粗大奥氏体晶界呈网状分布,存在明显脱碳现象,裂纹内富集As元素。分析表明圆坯表面网状裂纹的形成原因是钢中As元素含量高导致的奥氏体晶界As元素富集和过热度高导致的奥氏体晶粒粗大。据此进行了控制圆坯表面网状裂纹的工艺优化措施,控制钢中As元素质量分数在0.008%以内、控制钢水过热度在20~35℃、降低结晶器保护渣熔点并提高黏度,取得了显著效果。The characteristics and causes of reticular cracks on the surface of round bloom were analyzed by means of acid etching, electron microscope and electron probe test. It was found that the reticular cracks on the surface of round bloom were distributed in a reticular along the coarse austenite grain boundary, and there was obvious decarburization structure. The cracks were rich in As element. The analysis showed that the reasons of reticular cracks on the surface of round bloom were the enrichment of As element at austenite grain boundary caused by the high As mass fraction in molten steel and the coarseness of austenite grain caused by high superheat. Based on this, the optimization process to control the reticular crack on the surface of round bloom were carried out such as controlling the mass fraction of As in steel within 0.008 %,controlling the superheat of molten steel between 20-35 ℃,and reducing the melting point of mold flux and increasing the viscosity. Consequently, remarkable results were obtained.

关 键 词：网状裂纹 奥氏体晶粒 夹杂物 连铸圆坯 As富集 过热度 

分 类 号：TF777[冶金工程—钢铁冶金]