METHOD OF PRODUCING HARDENED PART NOT SUBJECT TO CRACKING UNDER ACTION OF LIQUID METAL Russian patent published in 2019 - IPC C21D1/673 C23C2/12 C21D8/04 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy. Method of hardened part production includes the following stages: a) obtaining a steel sheet with a metal coating, containing, wt%: from 2.0 to 24.0 zinc, from 1.1 to 7.0 silicon, from 1.1 to 8.0 magnesium, when the amount of silicon is between 1.1 and 4.0 wt%, and additional elements selected from Pb, Ni, Zr or Hf, with content of each less than 0.3 wt%, aluminum and unavoidable impurities – the rest, and in which ratio Al/Zn exceeds 2.9, b) cutting the coated steel sheet to produce a workpiece, c) heat treatment of workpiece at temperature of 840–950 °C to obtain austenitic microstructure in steel, d) transfer of billet into press die, e) hot forming of billet for part production, f) cooling the part obtained at step e) to obtain martensite or martensite-bainite microstructure or at least 75 % equiaxed ferrite, 5 to 20 % martensite and bainite in amount of less than or equal to 10 %.

EFFECT: excluding occurrence of cracks in part at hot stamping.

31 cl, 1 dwg, 2 tbl