Surface Roughness Study of High-Speed Railway Wheel Materials Based on Laser-Induced Breakdown Spectroscopy

An experimental platform of laser-induced breakdown spectroscopy (LIBS) is used to obtain the spectral information of seven ER8 high-speed train wheel samples with different surface roughnesses; the correlations between their spectral line intensities and the ratios of spectral line intensities to the surface roughnesses of the samples are investigated. The results show that the spectral line intensities of the base element Fe and the alloying elements Cr, Mo, and V, the intensity ratios of ion lines to atomic lines, and the spectral line intensity ratios of alloying elements to base elements are all correlated with the surface roughnesses of the samples to different degrees. In addition, random forest (RF) models with spectral line intensities and spectral line intensities with spectral line intensity ratios as variables are established using the correlations. The study shows that it is feasible to qualitatively analyze the surface roughnesses of high-speed railway wheel materials using laser-induced breakdown spectroscopy with an RF algorithm; this technique can be used to measure and evaluate the surface roughnesses of wheels in the field and provide some basis for the application of LIBS technology to the study of high-speed railway wheels with different surface roughnesses.