HOT-ROLLED STEEL SHEET AND RELATED METHOD OF MANUFACTURE Russian patent published in 2018 - IPC C22C38/38 C22C38/28 C21D8/04 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to hot-rolled steel sheet with a thickness of between 1.5 and 4.5 millimeters used in the automotive industry. Sheet is made of steel of the following chemical composition, wt.%: 0.04 ≤ C ≤ 0.08; 1.2 ≤ Mn ≤ 1.9; 0.1 ≤ Si ≤ 0.3; 0.07 ≤ Ti ≤ 0.125; 0.05 ≤ Mo ≤ 0.35; 0.15 < Cr ≤ 0.6; when 0.05 ≤ Mo ≤ 0.11; or 0.10 ≤ Cr ≤ 0.6; when 0.11 < Mo ≤ 0.35; Nb ≤ 0.045; 0.005 ≤ Al ≤ 0.1; 0.002 ≤ N ≤ 0.01; S ≤ 0.004; P < 0.020; the rest consists of iron and inevitable impurities resulting from processing. Microstructure of the sheet is formed of granular bainite, the percentage of which is more than 70 %, and ferrite, the percentage of which is less than 20 %, the rest, if there is any, consists of lower bainite, martensite and residual austenite, with the sum of martensite and residual austenite being less than 5 %.

EFFECT: yield strength of more than 680 MPa in the direction transverse to the rolling direction and less than or equal to 840 MPa, strength between 780 MPa and 950 MPa, an elongation at break of more than 10 % and an opening expansion factor (Ac) of 45 % is provided.

22 cl, 10 dwg, 4 tbl