High-strength bolt steel and method for producing the same

Abstract

This invention discloses a high-strength bolt steel and its production method. Its chemical composition and mass percentage are as follows: C 0.33%–0.40%, Si 0.15%–0.35%, Mn 0.90%–1.20%, Cr 0.45%–0.65%, Cu 0.25%–0.45%, Ni 0.25%–0.45%, P≤0.020%, S≤0.010%, with the balance being Fe and unavoidable impurities. This invention improves the strength of the bolt steel by adding Mn and Cr alloys, preventing bolt fracture under alternating and impact loads. The addition of Ni and Cu alloys improves the steel's strength and ductility; Cu has resistance to atmospheric corrosion, but it is prone to cracking during rolling; adding Ni can inhibit crack formation. The mechanical properties of this invention achieve a tensile strength ≥980 MPa, a yield strength ≥830 MPa, and an impact strength (Aku2) ≥60 J, meeting the performance requirements of high-strength bolts. The method of this invention adopts the process of "electric furnace smelting + continuous casting + continuous rolling", which is simple in production process.

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