40Mn2圆钢冷剪切裂纹形成原因及改进措施

Analysis on cold shear crack of 40Mn2 bar and its improvement measures

以不同厂家生产的Φ65mm圆钢为研究对象,采用化学分析、低倍组织、高倍组织检验等手段,分析了40Mn2圆钢冷剪切裂纹产生的原因。检验发现,钢材带状组织严重,高达3.0级;钢中存在SiO2-CaO-FeO、SiO2-MnO-FeO系夹杂物,且出现1.5级Ds类不变形夹杂。材料性能显示出强烈的各向异性,形成了冷剪切裂纹。据此进一步对炼钢连铸工艺过程及连铸坯分析,找出工艺缺陷,并针对性地制定了改进措施。

Taking different 065 mm bars made by different manufacturers as research object, the cold shear crack of 40Mn2 bar was analyzed by means of chemical composition, macrostructure and microstructure examinations. The results showed that the trip-shape structure was observable with level 3; SiO2-CaO-FeO, SiO2-MnO;FeO inclusions and the occurrence of grade 1. 5 class Ds non-deformation inclusion were observed. As a result, the properties of materials showed a strong anisotropy which can be considered the main reason of the cold shear crack. On this basis, further analyzing on the steelmaking process and slab quality was made to improve the technologies and put forward corresponding measures.