| 摘要 |
PROBLEM TO BE SOLVED: To provide a component carburized under the reduced pressure combining high fatigue resistance and pitting resistance, and to provide its production method. SOLUTION: The component carburized under the reduced pressure is obtained by subjecting a case hardening steel having a composition comprising, by mass, 0.05 to 0.4% C, 0.05 to 0.7% Si, 0.1 to 2.0% Mn, 0.003 to 0.020% N, and one or more kinds selected from 0.005 to 0.1% Nb, 0.01 to 0.1% Al and 0.01 to 0.4% Ti, and the balance Fe with inevitable impurities to forming into a prescribed shape, and subjecting the same to carburization under the reduced pressure, and, after the carburization under the reduced pressure, the depth of a crystal grain coarsened region comprising the crystal grains of≥80μm is≤0.25% of the depth of the carburized layer hardened to≥650 HV. Regarding this production method, the above steel is subjected to hot forging at high temperature, is thereafter subjected to the precipitation treatment of carbonitrides, and is thereafter subjected to carburization treatment under the reduced pressure. COPYRIGHT: (C)2008,JPO&INPIT
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