连铸坯宏观与半宏观偏析行为表征

为了深入了解连铸坯宏观偏析和半宏观偏析的分布特征,采用碳硫检测、化学分析、直读光谱、金属原位分析方法研究连铸坯厚度方向C、Mn元素宏观偏析行为;通过连铸坯低倍组织腐蚀和图像扫描处理方法探究半宏观偏析分布特征。研究结果表明,碳硫检测和直读光谱检测方法可定量分析C元素宏观偏析,而Mn元素适合采用直读光谱和金属原位分析方法,半宏观偏析可通过半宏观偏析面积比和半宏观偏析度实现定量表征。在连铸坯厚度方向,随着距铸坯表面距离的增加,C元素和Mn元素偏析不断波动,在铸坯中心处偏析较大。半宏观偏析主要存在于铸坯芯部,在枝晶转变区和铸坯中心处半宏观偏析度达到最大值。

Characterization of macrosegregation and semi-macrosegregation in continuous casting bloom

In order to obtain the distribution of macroscopic segregation and semi-macroscopic segregation in continuous casting bloom, the carbon-sulfur detection, chemical analysis, direct reading spectroscopy, and metal in-situ analysis were used to analyze the macrosegregation behavior of C and Mn elements in thickness direction of the bloom. The semi-macroscopic segregation distribution characteristics of continuous casting billet were investigated by low-power microstructure corrosion and image scanning processing. The result shows that the carbon-sulfur detection and direct reading spectroscopy detection are suitable for the macroscopic segregation detection of C. For the Mn segregation, the direct reading spectroscopy and metal in-situ analysis characterization methods are more appropriate. It also found the semi-macroscopic segregation degree can be quantitatively characterized by the semi-macroscopic segregation area ratio and the semi-macroscopic segregation degree. In the direction of the thickness of continuous casting bloom, the segregation of C and Mn elements fluctuates with the increase of the distance from the surface of the bloom, and the segregation is larger at the center of the bloom. The semi-macroscopic segregation mainly exists in the inner part of bloom, and the degree of semi-macroscopic segregation reaches the maximum in the dendrite transition zone and the center zone.