ALLOYED STEEL SHEET WITH MOLTEN ZINC COAT AND METHOD OF MANUFACTURE OF SUCH SHEET Russian patent published in 2007 - IPC C22C38/00 C22C38/58 C23C2/06 C21D1/26 

FIELD: manufacture of alloyed steel sheets with molten zinc coats by continuous electroplating method.

SUBSTANCE: proposed sheet has surface layer containing Fe at concentration of from 7 to 15 weight-%, Al at concentration of from 0.01 to 1 weight-%, the remainder being Zn and unavoidable admixtures. Surface layer includes also oxide particles of at least one type selected from Al oxide, Si oxide, Mn oxide, complex oxide of Si and Al, complex oxide of Si and Mn and complex oxide of Al, Si and Mn, either separately or in combination; average diameter of said oxide particles ranges from 0.01 to 1 mcm; heating temperature T is ensured at stage of recrystallization annealing of sheet in reduction furnace between 650 and 900°C ; steel sheet is passed through atmosphere where ratio of partial pressure of water vapor to partial pressure of hydrogen in atmosphere of said reduction surface ranges from 1.4·10^-10 ·T² - 1.0·10^-7·T+5.0·10^-4 to 6.4·10^-7·T²+1.7·10^-4·T - 0.1 forming oxide in area reaching the depth of up to 1.0 mcm from surface of steel sheet followed by application of galvanic coat of molten zinc on steel sheet and fusion of steel sheet with coat. Area of amorphous sections of Fe-Zn alloy phase in layer of coat is no less than 10% of total area of sheet.

EFFECT: enhanced strength and deformability of steel sheet.

7 cl, 1 dwg, 3 tbl