CARBURIZED COMPONENT AND MANUFACTURING METHOD THEREFOR

• Main Authors: NEISHI, YUTAKA, HAMADA, TAKANARI, SUGIURA, HIDEAKI, KOBAYASHI, YUJI, SUENO, HIDEKAZU
• Format: Patent
• Language: English; French; German
• Published: 10.08.2016
• 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

A carburized component has improved fatigue strength in a "low to medium cycle region", wherein base steel is a steel having a chemical composition containing, by mass%, C: 0.15-0.25%, Si: 0.03-0.50%, Mn: more than 0.60% and not more than 1.5%, P‰¤0.015%, S: 0.006-0.030%, Cr: 0.05-2.0%, Al‰¤0.10%, N‰¤0.03%, and O‰¤0.0020%, and optionally at least one element selected from Mo, Cu, Ni, B, Ti, Nb and V, the balance being Fe and impurities, wherein a surface hardened layer portion satisfies following conditions of (a) an average carbon concentration in the region from the outermost surface to a point of 0.2 mm depth: by mass%, 0.35-0.60%, (b) surface roughness Rz‰¤15 µm, and (c) Ãr(0) ‰¤-800 MPa, Ãr(100) ‰¤-800MPa, and residual stress intensity index Ir‰¥80000. The residual stress intensity index Ir is calculated by [Ir = ˆ«|Ãr(y)|dy], where y µm is the depth from the outermost surface and Ãr(y) is the residual stress for the points from the outermost surface to a depth of 100 µm. Here, the integration interval, that is, the range of y is 0 to 100 (µm).