Abstract: The generation mechanism and control technology of braking vibration and noise is a worldwide problem that the academia circle and engineers have been trying to solve for many years. In this study, laser surface quenching technique is employed to modify the frictional surfaces of four cast iron brake discs. The effects of laser quenching power on residual stress, damping coefficient, friction coefficient and braking vibrations and noise of brak discs are experimentally studied. The experiemntal results show that after laser quenching, the surface residual stress of the brake discs changes from tensile stress to compressive stress; the damping coefficient of brake discs increases with the increase of laser quenching power; the friction coefficient decreases with the increase of laser quenching power but becomes more stable, which effectively reduces braking fritional vibrations and noise. Particularly, the braking vibration of caliper reduces significantly, with a maximum reduction of RMS of the braking caliper to 30% of the original disc within the experimental range. This study is of great significance to the control of braking frictional vibrations and noise, reduction of brake wear, and improvement of the environment

Key words: brake disc, laser quenching, residual stress, frictional vibration and niose