Statistical Analysis Of Relation Of Manganese Sulfide Inclusion Area To Signal Intensity By Laser-Induced Breakdown Spectroscopy

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.