Papers by Author: Zdenek Pala

Abstract: LLocalized laser hardening of steel surfaces performed with optimal parameters not only hardens the surface layer, but is also capable of generating advantageous hook-like shape of residual stress depth distribution. Upon combining two most common methods of XRD and hole-drilling, the residual stresses up to the depth of 3 mm were analysed for two widths of high-powered diode laser beam. Narrower laser beam generates wider area with compressive stresses and the diffraction technique as compared with hole-drilling method always indicates higher values of compressive residual stress maxima.

Abstract: Inhomogeneous thermal fields and plastic deformation are two basic phenomena present during surface creation and substantially determine future real structure of the surface layers. In the following, a closer look will be taken at some aspects connected with real structure of milled and ground steels. Impact of end-mill speed and thickness of removed layer on grain size, macroscopic and microscopic residual stress is discussed. Possibility of prestrained surface layer in ground steel has been examined on a set of five types of steels.