COLD ROLLED STEEL PLATE Russian patent published in 2015 - IPC C22C38/04 C22C38/06 C22C38/38 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of cold rolled high strength steel plate. The plate is made out of steel with the following chemical composition in wt %: C: from 0.020 to 0.30; Si: from 0.10 to 3.00; Mn: from 1.00 to 3.50; P: maximum 0.10; S: maximum 0.010; sol. Al: at least 0 and maximum 2.00; N: maximum 0.010; rest - Fe and inevitable admixtures. Plate has metallurgical structure in which main phase is product of low temperature transformation, and second phase contains residual austenite. Volume part of the residual austenite is from 4.0% to 25.0% relative the full structure, and average grains size is below 0.80 mcm. Number density of grains of the residual austenite, with size 1.2 mcm or over is 3.0×10^-2 grains/mcm² or below.

EFFECT: assurance of high plasticity, ability for strain hardening and flanging-drawing, as well as tensile strength 780 MPa or over.

9 cl, 4 dwg, 3 tbl, 1 ex