ZINC-COATED STEEL FOR PRESS HARDENING APPLICATION AND METHOD OF PRODUCTION Russian patent published in 2018 - IPC C23C2/06 C23C2/28 C21D1/673 C21D1/78 

FIELD: metallurgy.

SUBSTANCE: invention relates to the production of a steel strip with an annealed zinc coating. Method includes the steps of steel being galvanized, followed by annealing to obtain a coating on the steel, and the galvanized annealed steel is subjected to pre-alloy heat treatment carried out prior to hot stamping at a temperature in the range of 850°F (454°C) to 950°F (510°C). Moreover, the steel is subjected to heat treatment with preliminary doping during the heat treatment time, which is determined in such a way that after the pretreatment heat treatment, the Fe content in the coating is in the range of 15 to 25 wt. %.

EFFECT: heat treatment with pre-alloying provides the possibility of obtaining the desired α-Fe phase in the coating by increasing the iron concentration in a shorter time at the austenitizing temperature, and also reduces the loss of zinc and ensures the formation of a more adherent oxide film after hot stamping.

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