钢中夹杂物是影响钢性能的重要因素。 有很多手段可以分析夹杂物的形貌尺寸和组成, 但同时分析夹杂物含量和尺寸的手段未见报道。 金相显微镜和扫描电镜等分析夹杂物尺寸要求样品表面精细制备, 通常钢铁样品要用800目砂纸打磨表面后用抛光膏磨成镜面, 费时费力。 采用激光诱导击穿光谱LIBS可以方便地同时分析钢中大于1 μm的夹杂物含量和尺寸分布, 同时LIBS分析时样品制备不需要像金相制样那样精细, 采用80目以上砂纸打磨表面, 无需将样品表面处理成镜面。 LIBS分析钢铁样品, 如果激发斑点激发到同时含有固溶元素及其夹杂物时, 均匀分布于基体铁中的固溶元素强度呈正态分布, 夹杂物作为夹杂元素的“富集体”会产生较高光谱强度并叠加在固溶光谱信号中, 可以将夹杂物产生的光谱强度解析分离出来, 这个解析出的夹杂物光谱强度包含了夹杂物尺寸大小和夹杂物平均浓度的信息。 夹杂物作为夹杂元素对比其固溶元素, 本质上相当于夹杂元素的“局部富集”, 在激发到夹杂物时, 富集的元素进入激发等离子体中释放出更强的分析谱线。 采用含Al2O3夹杂物及MnS夹杂物的钢铁样品, 以扫描电镜测得的夹杂物尺寸和面积测量结果作参照, 分析验证夹杂物面积、 尺寸与分析同样样品获得的LIBS的夹杂物光谱强度关联, 得出结论是夹杂物的面积与夹杂物光谱强度呈直线相关。 球状夹杂物的直径与夹杂物强度呈抛物线关系。 包含多个激发位置的夹杂物的平均浓度与夹杂物平均强度呈直线相关。 系统地给出了采用LIBS分析钢中夹杂物尺寸（面积）和夹杂物平均浓度的三个公式, 利用LIBS分析夹杂物的同一组光谱强度数据, 可以同时测定钢中夹杂物面积、 尺寸和含量。 分析了LIBS同时分析夹杂物尺寸（面积）和成分的原理。 并用钢中氧化铝夹杂物分析进行了验证, 理论公式和实际分析基本一致。

Inclusions are an important factor for steel performance. Many methods can be used to analyze the size and component. But no report was found that inclusion size and concentration was determined simultaneously. The metallographic microscope and SEM require fine polishing sample surface in inclusion analysis. Steel samples should be grinded at 800 mesh grinding paper and polished to mirror surface, and it is a time-consuming process. LIBS can analyze the inclusion size distribution over 1 μm and content average in steel and sample surface can be ground by over 80 mesh grinding paper, the mirror surface is not needed. When LIBS was used analyzing steel samples, if burn shot contains soluble element and its inclusion, homogenized soluble element in the matrix Fe presents in Gaussian distribution, inclusion as an “element concentrated area” yields high intensity than soluble element and additive to soluble element intensity. Inclusion intensity which was separated from the total intensity contains information of inclusion size and average inclusion concentration. When inclusion was excited, the enrichment element comes to the plasma and emit hight light intensity. Analyzing the steel samples which contain Al2O3 and MnS inclusions, the inclusion size and area were obtained and make a correlation with the LIBS inclusion intensity. The results show that the inclusion area and LIBS inclusion intensity are linear correlation, the diameter of globular inclusion and LIBS inclusion intensity are parabolic correlation. Average inclusion concentration which comes from multi-shot and LIBS inclusion intensity is linear correlation. Formulas （1）, （10）, （20）were given which using the same intensity data to analyze the inclusion size, area and concentration. The principle for simultaneous analysis of inclusion size (or area) and average content in steel by LIBS are explained. The Al2O3 inclusion in steel samples is analyzed and verified. The Al2O3 inclusion content analysis results and formula are coincided each other.