硫化锰夹杂物面积与激光诱导击穿光谱信号强度关系的统计分析

Statistical Analysis of Relation of Manganese Sulfide Inclusion Area to Signal Intensity by Laser-Induced Breakdown Spectroscopy

在风电主轴上制取金相试样(材料牌号34CrNiMo6),用激光诱导击穿光谱仪(LIBS)扫描分析了抛光表面上S、Mn、Fe、Cr、Mo、Si和Al等元素的二维分布。使用金相显微镜对比扫描分析前后的金相照片,提取了各烧蚀点覆盖区域的MnS夹杂物形貌,获得了S和Mn两元素异常信号分布特征及对应激发区域内的MnS夹杂物面积数据,分析了夹杂物面积与信号强度之间的关系。结果表明,S和Mn两元素基本都在相同位置出现异常信号,且两元素的异常信号强度具有明显的线性相关性,材料中的MnS夹杂物是引发S和Mn出现异常信号的最主要来源,并且MnS夹杂物面积与S和Mn两元素的异常信号强度之间存在较强的线性相关性,可以通过对异常信号的分析来识别MnS夹杂物并确定其尺寸及分布状态。通过建立简化物理模型,计算了MnS夹杂物面积与S和Mn两元素含量之间的关系,在低含量段,得到了夹杂物面积与S和Mn两元素含量之间近似呈线性关系的结果,进而验证了S和Mn两元素异常信号强度与MnS夹杂物面积之间线性相关的实验结果。分析认为,元素的宏微观偏析、夹杂物面积测量的偏差、预剥蚀导致的夹杂物剥落等因素都会对夹杂物面积与信号强度之间的线性统计关系产生影响。

Laser-induced breakdown spectroscopy( LIBS) was used for analysis of the distribution of S,Mn,Fe,Cr,Mo,Si,Al in a 34CrNiMo6 steel sample cut from a main shaft of wind driven generator. The MnS inclusion area in each ablation craters cover zone was extracted in the way of comparing the metallograph captured by optical microscopy before and after LIBS scanning ablation. The statistic relation between MnS inclusion area and signal intensity of S and Mn was analyzed. The result showed that the abnormal signal of S and Mn occurred at the same position with the existence of MnS inclusion,and their signal intensity showed linear relationship. The abnormal signal of S and Mn were triggered mainly by MnS inclusion. The statistic result also showed linear relationship between signal intensity and MnS inclusion area both for S and Mn. It was possible to determine the inclusion type,size and distribution by analyzing abnormal signal. A simplified ablation model was established to calculate the relation of S and Mn content to MnS inclusion area. The arithmetic result showed a linear relation between the content and MnS inclusion area both for S and Mn. The calculation confirmed the linear relationship between signal intensity and inclusion area observed in experiment. The linear relationship could be interfered by macro-segregation,micro-segregation,deviation in measuring inclusion area,and inclusion spatter in pre-ablation.