SUBJECTED TO FINISH ANNEALING, HIGH-STRENGTH STEEL SHEET WITH COATING, HAVING HIGH YIELD POINT AND IMPROVED DEGREE OF OPENING DISTRIBUTION Russian patent published in 2019 - IPC C21D8/04 C23C2/02 C21D9/48 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy. To increase the yield point and the degree of distribution of the hole of the annealed cold-rolled steel sheet with coating, the method involves obtaining a steel sheet containing the following in wt. %: C 0.1–0.3, Mn 1–3, Si 0.5–3.5, Al 0.05–1.5, Mo + Cr in range of 0.2–0.5, iron and unavoidable impurities - cold rolling of sheet, application of zinc coating on cold-rolled sheet to obtain cold-rolled sheet with coating with yield point between 550 and 580 MPa and degree of distribution of hole below 10 %, annealing of said steel sheet after application of said zinc coating, wherein said annealing after coating is carried out at temperature of 150–650 °C for a period of time sufficient to increase the yield strength of the annealed cold-rolled steel coated sheet by at least 40 % compared to the cold-rolled steel sheet immediately after coating, and increasing the degree of distribution of the hole of annealed cold-rolled steel sheet with coating by at least 80 % compared to cold-rolled steel sheet immediately after coating.

EFFECT: annealing is performed at a temperature and for a time sufficient to significantly increase the yield strength and hole expansion of the annealed coated cold rolled steel sheet as compared with the as coated sheet.

12 cl, 17 tbl, 12 dwg