| 摘要 |
A steel wire for a spring, in which the sag resistance and the fatigue characteristics are improved by production processes without addition of alloy elements, is provided. The spring has a structure obtained by quenching and tempering and includes a first layer at a surface thereof, a second layer interior to the first layer, and a third layer, which is interior to the second layer and reaches a center of the spring, and the second layer has lower hardness than the first and the third layers. |
