Selection of atomic emission lines on the mutual identification of austenitic stainless steels with a combination of laser-induced breakdown spectroscopy (libs) and partial-least-square regression (plsr)

Laser-induced breakdown spectroscopy (LIBS) is a promising method for the rapid determination of compositions of stainless steels in steel scrap. LIBS is widely known as a method for very rapid elemental analysis in open-air without any pretreatment. We applied a laboratory-build LIBS system for mutual identification of 5 types of austenitic stainless steels, SUS304, SUS310, SUS316, SUS321, and SUS347. The certified reference materials of JSM M 200 were employed for establishing supervised models, conducting partial-least-square regression (PLSR) for the determination of Cr, Ni, Mo, Ti, and Nb. Since it needed more than 10 minutes of calculation time when all the wavelength range were utilized for PLS2 regression, suitable emission lines in the determination were picked up for the reduction of calculation amount and time. When we select single emission lines having higher excitation levels to avoid an affection by self-absorption, the good determination results for Cr, Ni, Mo, and Nb could be obtained with reasonable accuracy and precision by the calculation with PLS1 regression.