磨球用钢连铸圆坯纵裂问题分析与控制

Analysis and control of longitudinal crack in continuous casting round billet of grinding ball steel

某钢厂在磨球钢连铸生产过程中,发现磨球钢圆坯表面存在不同程度的纵裂,严重纵裂位置伴随明显凹陷。通过对纵裂缺陷部位宏观形貌、微观结构和能谱分析,发现连铸圆坯纵裂处激冷层厚度不均匀,局部有增碳和残留R;O夹杂。本文根据连铸工艺的追溯情况,确定了连铸拉速、钢水过热度、二冷水工艺参数的异常,以及保护渣不稳定的传热和润滑是导致连铸圆坯纵裂的主要原因,并提出了控制改进措施。通过炼钢和连铸工序一系列工艺改进措施的实施,提高了钢水纯净度,稳定了连铸过热度和拉速,改善了连铸保护渣的使用性能,较好的解决了磨球用连铸圆坯的纵向裂纹问题。

During the continuous casting production of grinding ball steel in a steel plant, it was found that there were different degrees of longitudinal cracks on the surface of grinding ball steel round billet,and the serious longitudinal cracks were accompanied by obvious depressions. Through analyzing the macro structure, microstructure structure and energy spectrum of the longitudinal crack defect, the microstructure of uneven thickness of chilling layer, existing local carburization and residual R;O at the longitudinal crack of continuous casting round billet for grinding ball was determined. According to the continuous casting process tracing, this paper determines these are the main reasons for the longitudinal crack of continuous casting round billet, such as, the abnormal process parameters of continuous casting speed, molten steel superheat and secondary cooling water,along with unstable heat transfer and lubrication of mold flux, and put forward control improvement measures. Through the implementation of a series of process improvement measures in steelmaking and continuous casting processes,improved the purity of molten steel, stabilized the superheat and drawing speed of continuous casting, ameliorated the service performance of continuous casting protective slag, and the problem of longitudinal crack of continuous casting round billet for grinding ball is better solved.