HIGHLY CORROSION-RESISTANT GALVANIZED HOT-FORMED HARDENED STEEL, PART THEREFROM AND METHODS FOR MANUFACTURING THEREOF Russian patent published in 2025 - IPC C22C38/32 C22C38/38 C22C38/34 C22C38/28 C22C38/26 C22C38/24 C22C38/22 C23C2/06 C23C2/40 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: present invention relates to metallurgy, namely to corrosion-resistant galvanized hot-formed hardened steel used in the manufacture of automotive parts. Said steel comprises substrate and galvanic coating. Substrate contains the following components, wt.%: C 0.12–0.35, Si 0.08–2.12, Mn 0.42–10.00, Al 0.03–0.12, Cr 0.02–0.65, Mo ≤ 1.12, Nb + V + Ti 0.02–0.25, B 0.0003–0.005, S ≤ 0.012, P ≤ 0.08, the rest is Fe and unavoidable impurities. Galvanic coating contains the following components, wt.%: Al 0.15–0.45, Fe 0.05–2.50, La 0.08–3.2 and/or Ce 0.12–5.0, Si + Mn ≤ 3.0, Mg + Cr ≤ 3.5, the rest are Zn and unavoidable impurities. Galvanic coating contains a zinc layer and a diffusion layer, wherein the diffusion layer contains a restraining layer. Zinc layer has thickness of 6–20 mcm and mainly consists of a phase ηcontaining the following components, wt.%: solid solution Fe 0.08–2.20, Al 0.08–0.45, La 0.08–1.4 and/or Ce 0.12–2.0, Si + Mn ≤ 3.0, Mg + Cr ≤ 3.5, Si/Mn ≥ 1.1, Mg/Cr ≥ 0.8. Diffusion layer has thickness of 2–4 mcm, which is less than or equal to 40% of the thickness of the zinc layer, mainly consists of phases αFe and G. In diffusion layer αFe is greater than or equal to 80 wt.%, the average content of basic elements in the solid solution is, wt.%: Al 0.34–1.45, La 0.1–2.5 and/or Ce 0.2–3.1, Si + Mn ≤ 15.0, Mg + Cr ≤ 2.4. Retaining layer has thickness of 100–200 nm, which is 5–10% of the thickness of the diffusion layer, wherein the main component of the retaining layer is Fe₂Al₅.

EFFECT: high corrosion resistance and resistance to crack development.

7 cl, 9 dwg, 9 tbl, 30 ex