| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive high strength coil spring having strength and fatigue resistance higher than those of the conventional high strength coil spring, and to provide its production method. SOLUTION: An oil tempered wire in which chemical components and mechanical properties are controlled is used as the stock, and is made into a coil spring in which the thickness of a white layer formed by nitriding treatment is≤4μm, also, the hardness of the surface layer part (the part in the vicinity of 0.02 mm from the surface) is 700 to 900 by Hv, and the internal hardness in the part of 0.3 mm from the surface is≥580 by Hv. COPYRIGHT: (C)2006,JPO&NCIPI
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