HIGH-STRENGTH DIP-GALVANISED STEEL SHEET AND HIGH-STRENGTH ALLOYED AND DIP-GALVANISED STEEL SHEET OF FINE MOULDABILITY AND LOW MATERIAL ANISOTROPY WITH RUPTURE STRENGTH OF 980 MPA OR HIGHER, AND METHOD OF THEIR PRODUCTION Russian patent published in 2016 - IPC B32B15/18 C21D8/02 C21D9/46 C22C18/04 C22C38/06 C22C38/58 C23C2/28 

FIELD: metallurgy.

SUBSTANCE: steel sheet comprises the dip-galvanised ply formed on the base steel sheet surface. Proposed base sheet steel contains the following substances, in wt %: C - from 0.1 to less than 0.40, Si - 0.5-3.0, Mn - 1.5-3.0, O - not over 0.006 or less, P - not over 0.04 or less, S - not over 0.01 or less, Al - not over 2.0 or less, N - not over 0.01 or less, Fe and unavoidable impurities making the rest. The microstructure of said base steel sheet contains the following components, in vol %: ferrite - 40 or more, residual austenite - 8 or less than 60, bainite or martensite making the rest. The pole density of a particular crystal-lattice orientation is located in preset range at the sheet depth making 5/8-3/8 of the sheet base surface. Claimed dip-galvanised ply contains the following elements, wt %: Fe - less than 7, Z, Al and unavoidable impurities making the rest.

EFFECT: low anisotropy, good mouldability, breaking strength of 980 MPa or higher.

16 cl, 4 tbl, 3 dwg