HIGH-STRENGTH DIP GALVANISED STEEL PLATE, HIGH STRENGTH, ALLOYED, DIP GALVANISED STEEL PLATE WITH SUPERIOR MECHANICAL CUTTING CHARACTERISTIC, AND METHOD OF THEIR MANUFACTURING Russian patent published in 2015 - IPC C22C38/06 C22C38/04 C23C2/00 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: plate contains base steel plate with thickness from 0.6 to 5.0 mm, and formed on its surface by dip galvanisation of the coating layer. Base steel plate contains in wt %: C from 0.075 to 0.40, Si from 0.01 to 2.50, Mn from 0.80 to 3.50, P from 0.0001 to 0.10, S from 0.0001 to 0.01, Al from 0.001 to 2.0, O from 0.0001 to 0.01, N from 0.0001 to 0.01, and rest is for Fe and inevitable admixtures. In range from 1/8 to 3/8 of thickness from surface of the base steel plate with centre 1/4 of plate thickness the structure of the base steel plate contains 3 vol % or more residual austenite phase and from 40 to 90% ferrite phase. C content in solid solution of residual austenite phase is from 0.70 to 1.00 wt %. Average grain diameter of residual austenite phase is 2.0 mcm or below, and average distance between grains of residual austenite is from 0.1 to 5.0 mcm. Thickness of decarburised layer formed on part of surface layer of the base steel plate is from 0.01 to 10.0 mcm, average diameter of oxide grains on part of surface layer of the base steel plate is from 30 to 120 nm, and average their density is 1.0×10¹² oxides/m² or more.

EFFECT: production of steel plate with superior high mechanical cutting, plasticity, and with assurance of high strength at maximum tensile strength 900 MPa or more.

7 cl, 13 tbl