钢坯枝晶偏析定量的影响因素探讨

采用电子探针面分析及线分析的方法对380CL车轮钢坯中Mn元素的枝晶偏析进行定量分析试验,深入探讨了枝晶偏析定量的各种影响因素,包括加速电压、电子束流、驻留时间、累计频率、分析位置、分析尺寸等。结果表明:随着加速电压的增大,Mn的特征X射线强度计数增大,但空间分辨率降低;随着电子束流的增大,计数率呈正比例增大;随着驻留时间的延长,Mn含量值测量误差减小,但分析总时长增加;累计频率X取0.15时可最佳反映实际枝晶偏析的程度;不同分析位置的间距在20 mm以下时,偏析比值几乎相同;推荐面分析时区域尺寸在1 mm²以上,线分析时至少取水平线段1.2 mm、垂直线段0.9 mm的6条有代表性的分析线。面分析法定量统计性好,线分析法可行性强。

Discussion on influencing factors on the quantitative analysis of dendritic segregation of steel billets

The quantitative analysis tests of dendritic segregation of Mn in 380CL wheel steel billet were conducted by the means of mapping analysis and line analysis of electronic probe. Various influencing factors on quantitative analysis of dendritic segregation were discussed deeply, including accelerating voltage, beam current, dwell time, cumulative frequency, analysis position and analysis size and so on. The results showed that: when the accelerating voltage increased, the characteristic X-ray intensity counts of Mn increased, but meanwhile, the spatial resolution decreased; the counting rate increased in direct proportion to the increase of beam current; with the prolonging of dwell time, the measurement error of Mn content decreased, but the total analysis time increased; when the cumulative frequency (X) was 0.15, the degree of actual dendritic segregation could be well reflected; when the space at different analysis positions was less than 20 mm, the segregation ratio was almost same; it was recommended to choose at least 1 mm² area for mapping analysis, and six representative lines with 1.2 mm horizontal lines and 0.9 mm vertical lines for line analysis. The mapping analysis method had good statistical performance of quantitative results, while the line analysis method had good feasibility.