METHOD OF MANUFACTURING HOT ROLLED STRIP FROM BAINITIC MULTIPHASE STEEL COATED WITH Zn-Mg-Al AND RELATED HOT STRIP Russian patent published in 2019 - IPC C22C38/14 C22C38/12 C21D8/02 C23C2/06 

FIELD: metallurgy.

SUBSTANCE: invention relates to the production of hot-rolled strip of bainitic multiphase steel coated with Zn-Mg-Al. Steel is melted with following composition, wt. %: C 0.04–0.11; Si less than or equal 0.5; Mn 1.4–2.2; Mo 0.05–0.5; Al 0.015–0.1; P up to 0.02; S up to 0.01; B up to 0.006; at least one element from the group Nb, V, Ti in accordance with the following condition: 0.02 ≤ Nb + V + Ti ≤ 0.20, the rest is iron and impurities inevitable in steel smelting. Steel melt is poured to obtain a raw material in the form of a slab, or a block, or a thin slab. Raw material is subjected to hot rolling to obtain a hot rolled strip at the final rolling temperature in the range of 800–950 °C. Hot rolled strip is cooled to a temperature of less than 650 °C and winded up. Winded roll is cooled to room temperature in still air, and the microstructure of the winded hot rolled strip after hot rolling has a bainite content of more than 50 %. Annealing is performed by heating the hot rolled strip to a temperature above 650 °C and less than Ac3, preferably less than Ac1 + 50 °C. Hot rolled strip is cooled to the temperature of the zinc bath and apply a hot dip coating of the heated hot rolled strip into the zinc alloy melting bath with the content, wt. %: Al 1.0–2.0, Mg 1.0–2.0, the rest is zinc and inevitable impurities.

EFFECT: hot rolled strips have high strength, deformability, weldability and corrosion protection.

13 cl