Abstract
This paper describes a new large surface heat treatment method with a high power CO2 laser. The main feature of this method is to control the heat input on the surface of a carbon steel plate using a truncated pyramid mirror optical system and divided laser beams. A truncated pyramid mirror optical system enables to have a straighter beam trace on the surface than that by conventional polygon mirror system. This optical system can irradiate laser beams into a line at the surface of specimen. Each laser beam is located at the same interval. A 15kW CO2 laser and a 6 truncated pyramid mirrors are used for experiments to evaluate the new method. A large surface hardened zone without tempering on a carbon steel plate is achieved. The size of hardened layer is 60mm width, 0.6mm depth and 16mm length. This method would be very effective for continuous heat treatment of a very large steel plate without tempering.
