FIELD: metallurgy.
SUBSTANCE: invention relates to metallurgy, namely, to cold-rolled coated steel sheets suitable for use in automobiles. Cold-rolled coated steel sheet has a composition including the following elements, wt.%: 0.12≤carbon≤0.2, 1.7≤manganese≤2.10, 0.1≤silicon≤0.5, 0.1≤aluminium≤0.8, 0.1≤chromium≤0.5, 0≤phosphorus≤0.09, 0≤sulphur≤0.09, 0≤nitrogen≤0.09, and optionally contains one or several of the following elements: nickel≤3, niobium≤0.1, titanium≤0.1, calcium≤0.005, copper≤2, molybdenum≤0.5, vanadium≤0.1, boron≤0.003, cerium≤0.1, magnesium≤0.010, zirconium≤0.010, the rest of the composition being iron and inevitable impurities. The microstructure of the sheet contains, in percentages area, 15 to 60% bainite, 25 to 55% ferrite, 5 to 15% residual austenite, wherein the content of carbon in the residual austenite is between 0.7 and 1%, and 5 to 18% martensite, wherein the total amount of bainite and ferrite is at least 70%.
EFFECT: sheet is characterised by high values of strength and elongation, making it suitable for moulding and rolling while providing good weldability.
29 cl, 4 tbl, 11 ex
