What Kinds of Heat Treating are Appropriate for Lasers?
In general, lasers are not good heat sources for bulk heat treatment since laser light is very expensive in terms of dollars per joule. They are, however, appropriate for selective heat treatments such as localized hardening, tempering or annealing. Of these processes, transformation hardening of steel is the most common and the most interesting. There are, of course, many ways in which localized hardening of steel is accomplished. These can be divided into diffusion methods such as carburizing, where the steel s composition is locally changed to harden it, and selective hardening methods such as flame hardening, where heat is applied locally to transform an area. Selective hardening is done with sources such as flame, electrical induction or lasers which can be set to heat only a portion of an article. In contrast to diffusion hardening, the entire part must be composed of a steel which can produce the desired hardness. The heat source raises the selected area to the austenitizing tem
