600 MPa抗震钢筋条带状异常组织的分析与控制

针对600 MPa钢筋横截面心部附近出现明显的条带状异常组织,采用金相显微镜、SEM、EDS及维氏硬度方法对试样进行分析。结果表明:心部条带状异常组织为退化珠光体,该条带状组织主要由于冶炼工序的铸坯存在Mn元素偏析,并在后续轧制过程中形成的条状偏析带。针对上述情况,通过提高转炉出钢合金窄成分控制、采用高碱度大渣量、优化结晶器电磁搅拌参数、中间包低过热度及水口全程密封浇铸措施,有效改善了铸坯心部的元素偏析,避免了钢筋条带状异常组织的产生,提高了产品质量。

Analysis and control of abnormal band like structure of 600MPa seismic reinforcement steel rebar

In view of the obvious band like abnormal structure near the center of the cross section of the 600MPa steel bar, the samples were analyzed by metallographic microscope, SEM, EDS and Vickers hardness methods. The results show that the band like abnormal structure in the core is degenerate pearlite, which is mainly due to Mn segregation in the slab of smelting process and the strip segregation band formed in the subsequent rolling process. In view of the above situation, by improving the control of the narrow composition of the converter tapping alloy, adopting high basicity and large slag amount, optimizing the electromagnetic stirring parameters of the mold, low superheat of the tundish and the full sealing casting measures of the nozzle, the elements in the core of the slab are effectively improved. Segregation avoids the occurrence of abnormal band like structures of steel bars and improves product quality.