| 摘要 |
<p>Disclosed is a steel wire or bar which is used as a material for bolts and shafts applied to parts for machine structures having high strength. Having excellent cold forging properties, the steel wire consists of 0.10 - 0.40 wt% C, 1.0 wt % or less Si, 0.30 - 2.0 wt% Mn, 0.03 wt% or less P, 0.03 wt % or less S, and the balance of Fe and impurities, and is quenched and tempered so as to have a tensile strength of 70 - 130 Kgf/mm2. A ratio (d/TS) of area reduction (d, %) to tensile strength (TS) is 0.4 - 1.2. In the present invention, it is unnecessary to conduct spheroidizing for a long time. Furthermore, it is possible to produce a heat-treated steel wire, which has forging processabilitythat is the same as or superior to spheroidized steel wire, through brief quenching and tempering processes using a high frequency induction heating method, thereby improving productivity.</p> |
