| 摘要 |
PURPOSE: A steel wire used as a bead wire for automobile which not only maintains high strength and toughness but also represents a high elongation is provided, and a method for manufacturing the steel wire is provided. CONSTITUTION: In a steel wire comprising 0.4 to 0.65 wt.% of C, 0.1 to 1.0 wt.% of Si, 0.1 to 1.0 wt.% of Mn, 0.3 wt.% or less of Cr, 100 ppm(parts per million) or less of B and a balance of Fe and other inevitable impurities, wherein one or more elements selected from the group consisting of Ti, Nb and V is additionally contained in the steel wire in the amount range of 0.02 wt.% or less, and the structure of the steel wire comprises 10% or less of pro-eutectoid ferritic fraction and a balance of discontinuous pearlitic fraction, the high strength steel wire having a high elongation is characterized in that the steel wire is a bead wire for automobile that is continuously drawn by a series of dies which are adjusted to an approaching angle from a steel product to dies of 2α=7-9.5 degrees, a diameter of the final steel wire that is blowing heat treated to the temperature range of 490 to 560 deg.C is 1.6 mm or less, a salt patenting value 10d=28-36, an elongation is 5.0-8.2%, and a fraction of inner microvoids formed after drawing and blowing is 0.2% or less.
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