Easy Contact-Free Hardening of Parts with Difficult Access
During the laser skin hardening, the material (carbonaceous material) is heated up for a short time above austenitizing temperature and is transubstantiated by fast cooling down into the martensitic structure. Heat is generated by absorbing the laser radiation on the surface and the material is quenched by heat transportation inside. The surface may not melt up. The hardening depth is limited to approx. 1 to max. 1.5 mm by heat conductivity and self-quenching. Mainly the spot geometry of the laser at the processing spot and the feed rate determine the chronological temperature pattern.
Because of its square beam, the high power diode laser is particularly well-suited for large-surface applications in surface treatment, characterized by a “top-hat” intensity distribution in one beam direction and a Gaussian profile in the other direction. Compared to CO2 lasers, the diode laser benefits from its short wavelength (808 nm or/and 940 nm), which leads to increased absorption so that the usual nigrification does not apply. And compared to the Nd:YAG laser, the advantages due to the high efficiency of the diode laser are its beam profile and clearly lower investment and running costs.
- In the automotive construction parts can be hardened by the use of lasers in order to offer high strength against mechanical stress.