MANUFACTURING METHOD OF NITRIDED STEEL MEMBER

• Main Authors: KOBAYASHI ATSUSHI, MAEDA SUSUMU, SHIMIZU YUICHIRO, KANAYAMA MASAO, AKIMOTO KIYOTAKA
• Format: Patent
• Language: English; Japanese
• Published: 16.02.2017
• 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; 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

PROBLEM TO BE SOLVED: To provide a manufacturing method of a nitrided steel member of high strength and low strain that has high pitching resistance and high bending strength, and lower strain than that subjected to carburization or carbonitriding.SOLUTION: In a manufacturing method of a nitrided steel member, a steel member made of carbon steel for mechanical structure or alloy steel for mechanical structure is subjected to nitriding under a nitriding gas atmosphere at a flow velocity of the nitriding gas of 1 m/s or more and a temperature of 500-620°C to form an iron nitride compound layer of a thickness of 2-17 μm on the surface of the steel member, the nitriding gas having a partial pressure of NHgas of 0.08-0.34, a partial pressure of Hgas of 0.54-0.82, and a partial pressure of Ngas of 0.09-0.18 relative to the total pressure of 1.SELECTED DRAWING: Figure 2 【課題】高い耐ピッチング性と曲げ強度を有し、さらに浸炭や浸炭窒化処理と比較して低歪である高強度・低歪窒化鋼部材の製造方法を提供する。【解決手段】窒化鋼部材の製造方法において、機械構造用炭素鋼鋼材または機械構造用合金鋼鋼材からなる鋼部材を、全圧を１としたときに、ＮＨ３ガスの分圧比を０．０８〜０．３４、Ｈ2ガスの分圧比を０．５４〜０．８２、Ｎ2ガスの分圧比を０．０９〜０．１８とする窒化処理ガス雰囲気中で、窒化処理ガスの流速を１ｍ／ｓ以上とし、５００〜６２０℃で窒化処理することにより、鋼部材の表面に厚さが２〜１７μｍの鉄窒化化合物層を形成する。【選択図】図２