HIGH-STRENGTH FLAT STEEL PRODUCT HAVING BAINITIC-MARTENSITIC MICROSTRUCTURE AND METHOD FOR PRODUCING SUCH FLAT STEEL PRODUCT Russian patent published in 2018 - IPC C21D8/02 C21D9/46 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: to provide high strength rolled products with good ductility at the same time, as well as good weldability, flat rolled steel has a structure in a hot rolled state that does not contain ferrite, wherein the structure consists of ≥ 95 % by volume of martensite and bainite with a martensite fraction of ≥ 5 % by volume and in an amount of ≤ 5 % by volume of residual austenite, as well as due to the manufacture of inevitable components of the structure. Along with Fe and inevitable impurities, flat rolled steel contains, in wt. %: 0.08–0.10 C, 0.015–0.50 Si, 1.20–2.00 Mn, 0.020–0.040 Al, 0.30–1.00 Cr, 0.20–030 Mo, 0.020–0.030 Nb, 0.0015–0.0025 B, up to 0.025 P, up to 0.010 S, up to 0.006 N, in particular, 0.001–0.006 N. Impurities include up to 0.12 Cu, up to 0.090 Ni, up to 0.0030 Ti, up to 0.009 V, up to 0.009 Co, up to 0.04 Sb, 0.0009 W.

EFFECT: invention further provides a method with which flat steel products disclosed in accordance with the invention can be manufactured reliably and at reduced costs.

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