Laser beam hardening has been used in industrial applications since 1970. The potential of lasers in hardening, however, has not been fully explored until now. There exist many possibilities to increase the efficiency of laser beam hardening. They came into sight with the development of new laser sources such as rf-excited gas-lasers with the ability of fast modulation and high power Nd:Yag lasers.
By controllable lasers it is possible to build up a closed-loop regulation using a pyroelectric device to measure surface temperature and therewith controlling the laser output power. This system permits the surface temperature to be kept constant at a given value during the process. By very fast modulated rf-excited CO2 lasers a new system of beam shaping for surface modifications with lasers can be built. Deflection of the focussed laser beam in two directions using scanning mirrors and simultaneous variation of the laser power allows to form the intensity on the workpiece in shape and height. Moreover, the coupled laser power and beam form can be freely optimized even during the process.
Another possibility to increase the efficiency is the use of newly developed high power CO and solid-state lasers, which can be used to harden steels without absorptive coatings.
Experiments obtained with all described setups are shown and discussed.