| 摘要 |
PURPOSE: A U-bolt and a manufacturing method thereof are provided to omit a quenching/tempering heat treatment process, thereby simplifying manufacturing processes. CONSTITUTION: A U-bolt is composed of, in wt%: C: 0.15-0.50; Si: 1.5 or less; Mn: 0.25-2.0; P: 0.03 or less; S: 0.03 or less; and the remainder Fe and inevitable impurities. The U-bolt is formed by bending a steel wire which is treated with quenching which is followed by tempering to have tensile strength: 70-130Kgf/mm^2; yield ratio: 85-97%; sectional reduction ratio: 50% or more; and austenite crystal particle: ASTM No.9 or more. A bent part of the steel wire has more than 85% of tensile strength ratio, and, when the steel wire is drawn, more than 50% of sectional reduction ratio. The above mentioned compositions additionally include one composition among, in wt%: Cr: 0.05-2.0wt%; Mo: 0.05-1.0wt%; B: 0.0003-0.0050wt%; and Ti: 0.01-0.05wt%. [Reference numerals] (AA) Wire; (BB) Tempering; (CC) Cutting; (DD) Sign; (EE) U curve; (FF) Plating; (GG) Product |
