Laser Hardening

Contact-Free Hardening of Parts that are Difficult to Access

In the case of laser skin hardening with lasers, the material (carbonaceous steel) 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 beam on the surface and the material is quenched by heat transportation inside. The surface may not melt up. The hardening depth is limited to max. approx. 1.5 mm by heat conductivity and self-quenching. Mainly the spot geometry of the laser beam at the processing spot and the feed rate determine the chronological temperature pattern.
 
Because of their rectangular beam, the high “top hat” intensity distribution in one beam direction and a gauss profile in the other direction, high power diode lasers are particularly suitable for surface applications. Compared to CO2 lasers, diode lasers have the advantage of short wavelengths (808 nm or/and 940 nm) that lead to increased absorption so that the general nigrification is unnecessary. Compared to Nd:YAG lasers, the advantages of a diode laser are its beam profile and the clearly lower investment and running costs caused by the high efficiency.