| 摘要 |
PROBLEM TO BE SOLVED: To produce a steel wire for a steel code used as a reinforcing material for a tyre or the like, particularly a high strength extra fine steel wire excellent in fatigue characteristics after wire drawing and to provide a method for producing the same. SOLUTION: The high strength extra fine steel wire is the one contg., by weight, 0.80 to 1.20% C, in which the residual stress in the surface of the steel wire is regulated to -2000 to 200 MPa, the difference in Vickers hardness between the C cross-sectional surface layer and the center is regulated to <30, tensile strength is regulated to >=4500 MPa, and the fatigue limit is regulated to >=1000 MPa. By regulating the friction coefficient between a die and the steel wire to <0.07, the uniformity in the C cross-section of the steel wire is promoted, and the residual stress in the surface layer of the steel wire is controlled. |
