SURFACE TREATMENT METHOD FOR IRON ALLOY MATERIAL

• Main Authors: SUGIMOTO YOSHIHIKO, TAKAHASHI KATSUHIRO
• Format: Patent
• Language: English
• Published: 16.02.2012
• Subjects: CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; FORGE FURNACES; FORGING; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; HAMMERING; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PRESSING METAL; PUNCHING METAL; RIVETING; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS ORPROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL

PROBLEM TO BE SOLVED: To solve the following problems with a conventional surface treatment method for an iron alloy material: the diffused amount of diffusing elements serving as a diffusing agent is not sufficient and also a treatment agent has a short life, and therefore a treatment bath may change with time to cause a variation in forming a hardened layer.SOLUTION: In the surface treatment method, after performing a pre-nitriding treatment on a surface of the iron alloy material (material to be treated), a diffusion treatment is performed to form a surface hardened layer. After performing a nitriding treatment on the surface of the iron alloy material, actually nitrided material to be treated is heated and retained in 400-700 °C molten salt, thereby forming the surface hardened layer consisting of a nitride or a carbonitride of one or more types of elements such as a group 4-7 element in the fourth to sixth period in the periodic table on the material to be treated.