STEEL WITH CONTROLLED RATIO OF YIELD STRENGTH TO TENSILE STRENGTH AND METHOD OF ITS MANUFACTURE Russian patent published in 2023 - IPC C22C38/58 C22C38/54 C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 C21D8/06 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to the production of steel used for the manufacture of mooring chains for offshore platforms, mechanical structures and sheets for automobiles. Steel includes the following components, in wt.%: C: 0.245-0.365, Si: 0.10-0.80, Mn: 0.20-2.00, P: ≤ 0.015, S: ≤ 0.003, Cr: 0.20-2.50, Mo: 0.10-0.90, Nb: 0-0.08, Ni: 2.30-4.20, Cu: 0-0.30, V: 0.01-0.13, B: more than 0 and 0.0020 or less, Al: 0.01-0.06, Ti: 0-0.05, Ca: ≤ 0.004, H: ≤ 0.0002, N: ≤ 0.013, O: ≤ 0.0020, the rest is Fe and inevitable impurities. The contents of steel components satisfy the following relations: (8.57*C+1.12*Ni)≥4.8% and 1.2%≤(1.08*Mn+2.13*Cr)≤5.6%. The microstructure of steel is tempered martensite and tempered bainite. The yield strength to tensile strength ratio of the specified steel is 0.85-0.95, the tensile strength is 1100 MPa or more, and the yield strength is 935 MPa or more.

EFFECT: steel has the required high strength and toughness.

6 cl, 2 dwg, 2 tbl, 8 ex