HIGH-STRENGTH STEEL HAVING HIGH DEFORMABILITY, AND METHOD OF PRODUCING SUCH STEEL Russian patent published in 2020 - IPC B32B15/01 C22C38/00 C22C38/02 C22C38/06 C22C38/26 C22C38/38 C23C2/02 C23C2/06 C23C2/40 C21D8/02 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to sheet steel suitable for automotive industry. Chemical composition of coated steel sheet: 0.17 % ≤ carbon ≤ 0.24 %, 1.9 % ≤ manganese ≤ 2.2 %, 0.5 % ≤ aluminium ≤ 1.2 %, 0.5 % ≤ silicon ≤ 1 %, 0.05 % ≤ chromium ≤ 0.2 %, 0.015 % ≤ niobium ≤ 0.03 %, phosphorus ≤ 0.03 %, sulphur ≤ 0.004 % and at discretion of 0.005 % ≤ titanium 0.0 5%, 0.001 % ≤ molybdenum 0.05 %, iron and unavoidable impurities remaining as a result of treatment. Si + Al ≥ 1.3 %. Microstructure of sheet steel with coating contains in fractions of area of 10–20 % residual austenite, wherein phase of said austenite has carbon content of 0.9–1.1 %, 40–55 % of polygonal ferrite, 15-40 % of granular bainite and at least 5 % of tempered martensite, wherein total amount of tempered martensite and residual austenite is 20–30 %.

EFFECT: higher deformability and high strength.

19 cl, 3 dwg, 6 tbl