HIGH-STRENGTH STEEL PLATE WITH EXCELLENT IMPACT STRENGTH, AND METHOD OF ITS MANUFACTURING, AND HIGH-STRENGTH GALVANISED STEEL PLATE, AND METHOD OF ITS MANUFACTURING Russian patent published in 2016 - IPC C22C38/14 C21D8/02 C23C2/02 C23C2/28 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to high-strength steel plate used in motor-car production. Sheet is made of steel containing in wt %: C from 0.075 to 0.3, Si from 0.3 to 2.5, Mn from 1.3 to 3.5, P from 0.001 to 0.05, S from 0.0001 to 0.005, Al from 0.001 to 0.05, Ti from 0.001 to 0.015, N from 0.0001 to 0.005, O from 0.0001 to 0.003, and rest is for Fe and inevitable admixtures. Plate steel has structure that in range from 1/8 to 3/8 of plate thickness after 1/4 of plate thickness contains 1-8% of residual austenite in volume fractions, average ratio of grain side lengths of the residual austenite is 2.0 or below, quantity of manganese in solid solution in the residual austenite exceeds average quantity of Mn in steel by 1.1 times or over, TiN particles are contained, they have average diameter 0.5 micron or below, and density of AlN particles with grain diameter 1 mcm or over is 1.0 particles/mm² or below.

EFFECT: plate has maximum tensile strength 900 MPa or over, and high impact strength.

12 cl, 19 tbl, 1 ex