| 摘要 |
<p>A high-strength bolt having a bolt tensile strength of at least 1200 N/mm2 and being excellent in delayed fracture resistance characteristics and its steel product. A high-strength bolt having its head and shank formed of a steel product, wherein the steel product is so regulated in quality that the relation between a bolt tensile strength TS (N/mm2) and a tempering temperature T (°C) satisfies the following expression (1), the relation between the bolt tensile strength TS and a carbon equivalent C¿eq? (%) calculated from its chemical components satisfies the following expression (2), and a bolt tensile strength by hardening and tempering ranges from 1200 N/mm?2¿ to 1600 N/mm2. TS ≤ 1.1T + 850 .....(1) TS ≤ 550C¿eq? +1000 ....(2) where, Ceq = C + (Mn/6) + (Si/24) + (Ni/40) + (Cr/5) + (Mo/4) + (V/14).</p> |
