SURFACE HARDENING METHOD BY CARBURIZATION HARDENING OF PURE IRON AND LOW CARBON STEEL BY LASER

摘要

PURPOSE:To form a high hardeness surface layer which is hardened by carburization hardening and is highly resistant to wear by coating a black film of a carbon-contg. material on the surface of pure iron or low carbon steel and hardening by laser. CONSTITUTION:A carbon-contg. material such as black magic ink or the like which prevents laser reflection and generates a carburizing effect is coated on the surface to be worked of pure iron or low carbon steel by which a black film treatment is applied on said surface. Laser is then irradiated thereto in a home position and the material to be worked is moved continuously. The surface of said material subjected to the irradiation of the laser is heated to a high temp. and the black film is thermally decomposed to form nascent carbon. The carbon penetrates in the material to be worked and said material is thus carburized. Austenite texture is formed near the surface by the high temp. heating. The irradiated part is quickly cooled by the heat transmission to the non-irradiated part and the carburized part is transformed from the austenite texture to martensite texture so that the surface-hardened layer by the carburization hardening having high hardness is formed.