Numerical analysis of laser cleaning in steel rail: effect of rust layer thickness

In this study, a finite element model was established to investigate the variation of the temperature field under different rust layer thicknesses on laser cleaning in steel rail. QU70 high-carbon steel rail substrate was applied. The simulation results have demonstrated that the highest temperatures are at the edge area of each track during the multi-track scanning of laser cleaning process due to heat accumulation. To reduce the influence of heat accumulation, it is necessary to control the input laser energy at the edge of the scanning area. On the other hand, when the thickness of the rust layer increases, higher laser energy is required to remove the rust effectively. However, since the melting point and latent heat of the rust are higher than those of the substrate, higher laser energy may cause damage to the substrate. Therefore, the laser power needs to be reasonably controlled during laser cleaning to minimize damage to the substrate. Furthermore, during the multi-track scanning of laser cleaning process, the thermal cycling can induce remelting in the area where rust has already been removed. Such thermal effects may lead to microstructural alterations and surface morphology changes in the affected regions. Hence, process parameters need to be optimized to prevent negative influences on the substrate in the remelted area.