COLD-ROLLED STEEL PLATE WITH ZINC OR ZINC ALLOY COATING, METHOD OF ITS PRODUCING AND SUCH STEEL PLATE USE Russian patent published in 2016 - IPC C21D1/20 

FIELD: metallurgy.

SUBSTANCE: invention can be used, in particular, in the automobile industry, and relates to manufacturing of the cold-rolled and annealed steel plate with TRIP-effect. The steel plate has the following composition, wt %: 0.17≤C≤0.25, 1.5≤Mn≤2, 0.50≤Si≤1, 0.50≤Al≤1.2, wherein Si+Al≥1.30, the rest is for iron and inevitable admixtures produced as a result of treatment. The plate microstructure in percents of the area is from 65 to 85% ferrite, and from 15 to 35% martensite and residual austenite spots. An average size of the said martensite and residual austenite spots is below 1.3 micron, and their average form factor is below 3. The mechanical strength Rm of the plate is from 780 to 900 MPa inclusively, and the fracture elongation A% is above or equal to 19%.

EFFECT: combination of high strength and high formability.

17 cl, 3 dwg, 5 tbl