| 摘要 |
There is provided a hot forged product. By appropriately controlling the structure during the hot forging process, the fatigue strength of the hot forged product required to cope with the increased susceptibility to stress caused by the reduction in size and weight is, for example, 20% higher than that of a forged product manufactured by an existing method. In addition, the areas which are not required to have high fatigue strength, as well as other areas, provide a good machinability when subjected to machining after hot forging, which enables easy finishing. The hot forged product has hardened areas introduced by partial cooling after hot forging, and unhardened areas, wherein Vickers hardness V 1 of the hardened areas on the surface and Vickers hardness V 2 of the unhardened areas satisfy (V 1 - V 2 )/V 2 : 0.1 to 0.8. |
