HIGH STRENGTH EXTRA FINE STEEL WIRE EXCELLENT IN TWISTING CHARECTERISTIC AND MANUFACTURE THEREFOR

摘要

PROBLEM TO BE SOLVED: To provide a steel wire for a steel cord used for the reinforcement of a material for tires or the like, especially a high strength extra fine steel wire excellent in twisting characteristic and to provide a method therefor. SOLUTION: A high tension strength extra fine steel wire excellent in twisting characteristic having the tensile strength of >=4500 MPa contains 0.80-1.20 weight % C to have H<=d/200 (where H: the average width of strip state smooth part on the steel wire surface [mm], d: diameter of wire [mm]) and to have a Vickers hardness difference between cross sectional surface layer and the center of <30 and the coefficient of friction between a dies and the steel wire at the time of wet type working of extra fine steel wire is made to be <0.07.