HARDENING TREATMENT METHOD OF LOW ALLOY STEEL

• Main Authors: NAGAMATSU HIROKAZU, INOUE TAKASHI, KANAZAWA SEIJI, ICHIKI RYUSUKE, AKAMINE SHUICHI
• Format: Patent
• Language: English
• Published: 19.06.2014
• Subjects: ALLOYS; 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; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PROBLEM TO BE SOLVED: To provide a hardening treatment method capable of surface layer hardening treatment of a low alloy steel having a small content of a rare metal or not containing a rare metal.SOLUTION: In a hardening treatment method of a low alloy steel, the surface of the low alloy steel is irradiated with a plasma jet of nitrogen gas containing hydrogen gas added thereto under an atmospheric pressure to heat a surface layer of the low alloy steel to an austenitic transformation point temperature or higher, and to thereby diffuse nitrogen atoms onto the surface layer of the low alloy steel; and further, the low alloy steel is hardened to generate martensitic transformation of the surface layer of the low alloy steel, to thereby generate a nitrogen martensite phase.