激光诱导击穿光谱对34CrNiMo6钢中硫化锰夹杂物的评级表征

使用激光诱导击穿光谱(LIBS)对钢铁样品的扫描分析过程中,MnS夹杂物会引发S和Mn同时出现异常信号,并且信号强度与夹杂物面积之间存在线性关系.应用上述特征并参考德国标准DIN 50602中的检验要求,提出了一个用LIBS进行MnS夹杂物评级的方法.实验方法中,首先要在样品上统计得到的S、Mn元素信号强度与夹杂物面积...

Rating characterization of manganese sulfide inclusion in 34CrNiMo6 steel by laser-induced breakdown spectroscopy

During the scanning analysis of steel sample by laser-induced breakdown spectroscopy (LIBS), MnS inclusions would cause the abnormal signal both for S and Mn at the same time. Moreover, the signal intensity had linear relationship with the inclusion area. According to the above characteristics and the inspection requirements in German standard DIN 50602, a rating method for MnS inclusions by LIBS was proposed. In experimental method, the fitted curves between signal intensity and inclusion area for both S and Mn elements were obtained based on specimen statistics, and the curves were used as calibration curves. Then the field of view with highest total signal intensity of characteristic elements in inclusion was found within the scanning region and used as the field of view with most inclusions. The inclusion area in the field of view was obtained by inversion calculation with the signal intensity of inclusions according to the calibration curve. Finally, the rating grade was calculated according to the relational expression between rating grade and inclusion area. The contrastive analysis of the proposed LIBS method and traditional metallographic method was implemented on 34CrNiMo6 steel specimen for the main shaft of wind generator. The results showed that, when the content of MnS inclusion was low (n<3), the results of Mn obtained by the LIBS method had significant difference with those obtained by the traditional metallographic method. But the results of S were basically consistent for both methods. When the content of MnS inclusion was high(n≥3), the analysis results of S and Mn by the proposed LIBS method were in good agreement with those obtained by the traditional metallographic method. The proposed method could meet the precision requirements of conventional metallographic examination.