Analysis of Ti-inclusions in high carbon chromium bearing steel by laser-induced breakdown spectroscopy.

The presence of Ti-inclusions has a significant impact on the fatigue life of bearing steel. Laser-induced breakdown spectroscopy (LIBS) is a useful tool for analyzing Ti-inclusions, despite the fact that the effective excitation area of LIBS is actually larger than the pre-set spot diameter. The area affected by the LIBS spot ranges from 150 μm to 376.6 μm. A new parameter L has been introduced for better understanding the characterization of Ti-inclusions detected in SEM-EDS and LIBS measurements, When the L threshold falls below the value of 188.3 μm, the SEM-EDS and LIBS data are obtained from the same Ti-inclusion. The study demonstrates that there is a linear relationship between LIBS intensity and Ti-inclusions area, which was tested both theoretically and practically. The analysis of six samples of rolling GCr15 bearing steel with a Cr element content of 1.5% shows that one regression line is enough for analyzing the same type of inclusion processed under the same conditions. This method can significantly reduce the workload and analysis time during the actual analysis process.