Jae Do Kim - Inha University
Young Gon Lee
Sang Kyun Lee

Laser beam hardening of 12%-Cr steel has been evaluated by using a continuous wave 3 kW CO2 laser. A fine lamellar martensite formed in the hardened zones exhibits very high Vickers microhardness of 600 Hv, whereas the tempered martesite distributes in the base metal with 240 Hv. To improve the wide area of laser processing the polygon mirror device is designed and manufactured, which is able to adjust the amplitude and frequency. It consists of a rotating pyramidpolygon mirror made of copper and converts the spot laser beam into the line shaped beam. The quenching heat treatment is also processed on carbon steel with high power laser. The hardened width is obtained up to 17 mm by single scanning

12% Cr steel, Laser quenching, Pyramid polygon mirror