HOT-FORGED PRODUCT EXCELLENT IN FATIGUE CHARACTERISTIC, AND PRODUCTION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a profitable producing method for forged product having excellent fatigue strength, such as≥400 MPa rotation bending fatigue strength by suitably controlling the structure in a hot-forging process. SOLUTION: When the hot-forged product is produced by applying plural times of hot-forgings to a steel blank composed of 0.3-0.9 mass% C, 0.01-1.2 mass% Si, 0.01-2.0 mass% Mn and the balance Fe with inevitable impurities; in the finish-forging process, plurality of directional component stresses are applied under temperature range of≥A1point to≤A3point+100°C and the stress of two or more components in the plurality of directional components, are made to respectively≥0.5. COPYRIGHT: (C)2007,JPO&INPIT