According to the announcement from the State Intellectual Property Office, Baoshan Iron and Steel Co., Ltd. applied for a project called "A wire rod and bolt for nickel-saving high-strength weather-resistant bolts and their manufacturing method", with the publication number CN117778895A, and the application date is September 2022.
The patent abstract shows that the invention discloses a wire rod for nickel-saving high-strength weather-resistant bolts, which contains Fe and inevitable impurity elements. It also contains the following chemical elements in the following mass percentages: C: 0.15-0.25 %, Si: 0.01‑2.0%, Mn: 0.3‑2.2%, Cr: 2.5‑4.5%, Ni: 0.01‑0.1%, Cu: 0.2‑0.6%, Al: 0.001‑0.1%, Ti: 0.01‑0.5% ; And the mass percentage content of Cr and C meets: Cr/C>10; the wire rod for nickel-section high-strength weather-resistant bolts does not contain V. Correspondingly, the present invention also discloses a bolt made from the above-mentioned nickel-free high-strength weather-resistant bolt wire rod that has been at least quenched and tempered. At the same time, the invention also discloses a manufacturing method for the above-mentioned bolts, which specifically includes the steps: (1) smelting and casting; (2) heating; (3) rolling; (4) cooling: after rolling, heat at 4-5°C/ s cooling rate to below 900°C, and then continue cooling to room temperature at a cooling rate of 0.3 to 0.5°C/s.
