TEMPERED COATED SHEET STEEL WITH EXCELLENT DEFORMABILITY, AND ITS MANUFACTURING METHOD Russian patent published in 2021 - IPC C22C38/06 C22C38/12 C22C38/14 C22C38/38 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to tempered coated sheet steel used for the manufacture of vehicle parts. Steel has a chemical composition containing following elements, expressed in wt.%: 0.17 ≤ carbon ≤ 0.25, 1.8 ≤ manganese ≤ 2.3, 0.5 ≤ silicon ≤ 2.0, 0.03 ≤ aluminum ≤ 1.2, sulfur ≤ 0.03, phosphorus ≤ 0.03, optionally at least one element of: chrome ≤ 0.4, molybdenum ≤ 0.3, niobium ≤ 0.04 and titanium ≤ 0.1, the rest is iron and inevitable impurities. The microstructure of sheet steel includes in fractions of the surface area from 3 to 20% of residual austenite, at least 15% of ferrite, from 40 to 85% of tempered bainite and at least 5% of tempered martensite, wherein the total amount of tempered martensite and residual austenite are in the range from 10 to 30%.

EFFECT: steel has the required level of tensile strength, relative elongation and hole distribution coefficient.

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