HEAVY-DUTY STRUCTURAL STEEL AND MANUFACTURING METHOD THEREOF Russian patent published in 2016 - IPC C22C38/58 C22C38/50 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely production of hot-rolled structural steel sheet with thickness of 2-12 mm,Steel has following composition, wt%: C: 0.07-0.12, Si: 0.1-0.7, Mn: 0.5-2.0, Ni: 1.5-4.5, Cu: 0.25-3.0, Cr: 0.5-1.6, Mo: 0.1-0.8, Ti: 0.005-0.04, V: less than 0.1, if necessary, one or more components from: B: less than 0.0003 or 0.0005-0.003 provided that content of titanium makes 0.02-0.04 or satisfies condition 3*N(%)<Ti≤0.04 %, Nb: 0.008-0.08 or less than 0.008, Ca: 0.0005-0.005, Al: 0.01-0.15 , iron (Fe) and unavoidable impurities, in particular N: ≤0.01, P: <0.02, S <0.04. Carbon equivalent of C_E of structural steel, calculated from expression C_E= (C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15) is equal to 0.5-1.2 to ensure ability for hardening of weld re-austenitisation zone, executed on such steel. Ultimate tensile strength of steel at break R_p0.2 is at least 960 MPa, and microstructure is more than 80 % of martensite and/or self-hardening martensite.

EFFECT: obtaining high-strength steel with high impact strength of thermal influence zone of weld joints.

37 cl, 4 dwg, 2 tbl