Effects of laser heat treatment on mechanical properties of ceramic coated steels Part 1 – Laser irradiation conditions and mechanical properties of ceramic coated steels

In our previous study, we proposed a new surface modification technique by combination of ceramic coating and laser heat treatment. By applying laser heat treatment after coating, it was possible to improve the adhesive strength and substrate hardness of ceramic coated steels without compromising the film hardness. In the present research, in order to quench a larger area of ceramic coated steel uniformly and efficiently, a high power diode laser equipped with a galvano-scanner was used in the laser heat treatment process. The scanning laser irradiation conditions to achieve uniformly quenched substrates without any surface damage were investigated for three kinds of ceramic coated steels: CrAlN, TiAlN and CrN. The film hardness and adhesive strength of the laser irradiated regions were evaluated. It is shown that scanning laser quenching after coating effectively improved the mechanical properties for larger area of ceramic coated steels.