| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an ultra fine steel wire having high strength and high toughness, preferably having >=3,720 N/mm2 tensile strength, and excellent in longitudinal crack resistance. SOLUTION: The residual stress in the surface of the ultra fine steel wire is regulated to <=157×InD+273 N/mm2 (where D is the diameter pf the extra fine steel wire after final drawing, (mm)). As the chemical components of the steel wire, 0.8-1.1%, by weight, C, 0.1-0.5% Si, 0.15-0.6% Mn, 0.05-0.4% Cr, 0.05-0.8% Cu and <=0.03% Al can be cited. The steel wire can be manufactured by subjecting a wire rod, having (1,270 to 1,570) N/mm2 tensile strength after final patenting treatment and <=0.02% area ratio of pro-eutectoid ferrite and/or pro-eutectoid cementite, to drawing at >=3.3 true strain and further skin pass rolling to regulate the residual stress in the surface of the resultant steel wore so that it satisfies the above condition.</p> |
