A cold rolled steel flat product for packaging made of a low carbon steel having a thickness of less than 0.49 mm and a method of making. The steel flat product has a martensite-free microstructure and represents a standard grade for packaging with tensile strengths from 300 to 550 MPa, which can be produced from a cold-rolled steel sheet with a carbon content from 0.01% to 0.1% by weight by inductive annealing of the steel sheet and subsequent water cooling for quenching the recrystallization-annealed steel sheet. To achieve flatness of 5 I-units or less, the induction annealed steel sheet is first primarily cooled in the manufacturing process to a take-off temperature at a rate of less than 1000 K/s, with the take-off temperature being below the transformation temperature of 723° C., and thereafter a secondary cooling by water cooling with a water temperature of less than 80° C. at a rate of more than 1000 K/s.

A method for manufacturing a product from a flexibly rolled strip material includes the steps of: providing a strip material made from sheet steel; flexibly rolling the strip material such that a variable thickness is produced along the length of the strip material; electrolytically coating the strip material with a metallic coating material containing at least 93% of zinc by mass after the flexible rolling; heat treating at temperatures above 350° C. and below a solidus line of the coating material after the electrolytic coating; working a blank from the flexibly rolled strip material; and hot forming the blank.

A cold-rolled and recrystallization-annealed flat steel product may include a ferritic microstructure, which possesses optimized formability and suitability for a wide variety of applications, including painting, for example. The flat steel product may include a steel comprising (in percent by weight): C: 0.0001%-0.003%, Si: 0.001%-0.025%, Mn: 0.05%-0.20%, P: 0.001%-0.015%, Al: 0.02%-0.055%, Ti: 0.01%-0.1%. The steel may further include at least one of Cr: 0.001%-0.05%, V: up to 0.005%, Mo: up to 0.015%, or N: 0.001%-0.004%, which may have the following mechanical properties: Rp0.2≦180 MPa, Rm≦340 MPa, A80≦40%, and n value ≦0.23. At least one surface may have an arithmetic mean roughness Ra of 0.8-1.6 μm and a peak count RPc of 75/cm. The present disclosure also concerns methods for producing flat steel products.

The invention relates to sheet steel, more particularly a coated sheet steel, which is skin-pass rolled with a deterministic surface structure, and to a method for producing this steel.

Provided is a high-strength cold rolled steel sheet, a high-strength hot-dip galvanized steel sheet manufactured using the cold rolled steel sheet, and manufacturing methods therefor, the high-strength cold rolled steel sheet comprising, by wt %, 0.17-0.21% of carbon (C), 0.3-0.8% of silicon (Si), 2.7-3.3% of manganese (Mn), 0.3-0.7% of chromium (Cr), 0.01-0.3% of aluminum (Al), 0.01-0.03% of titanium (Ti), 0.001-0.003% of boron (B), 0.04% or less of phosphorus (P), 0.02% or less of sulfur (S), 0.01% or less of nitrogen (N) and the balance of iron (Fe) and other inevitable impurities, wherein the amounts of carbon (C), silicon (Si) and aluminum (Al) satisfy the following mathematical relation (1). [Mathematical relation (1)] [C]+([Si]+[Al])/5≤0.35% (wherein [C], [Si] and [Al] respectively mean the wt % of C, Si and Al.)

In a metal coated steel sheet, a chemical composition contains, in mass %, at least C: 0.03% to 0.70%, Si: 0.25% to 2.50%, Mn: 1.00% to 5.00%, P: 0.100% or less, S: 0.010% or less, sol. Al: 0.001% to 2.500, N: 0.020% or less, and a balance composed of iron and impurities, a metal structure contains greater than 5.0 vol % of retained austenite and greater than 5.0 vol % of tempered martensite, and satisfies a C content in the retained austenite being 0.85 mass % or more.

A high strength steel strip having medium amounts of C, Mn, Si, Cr and Al, wherein the steel strip has a microstructure consisting of, in vol. %: ferrite and bainite together 50-90%, martensite<15%, retained austenite 5-15%, the remainder being pearlite, cementite, precipitates and inclusions together up to 5%.

Provided is a high-strength cold rolled steel sheet, a high-strength hot-dip galvanized steel sheet manufactured using the cold rolled steel sheet, and manufacturing methods therefor, the high-strength cold rolled steel sheet comprising, by wt %, 0.17-0.21% of carbon (C), 0.3-0.8% of silicon (Si), 2.7-3.3% of manganese (Mn), 0.3-0.7% of chromium (Cr), 0.01-0.3% of aluminum (Al), 0.01-0.03% of titanium (Ti), 0.001-0.003% of boron (B), 0.04% or less of phosphorus (P), 0.02% or less of sulfur (S), 0.01% or less of nitrogen (N) and the balance of iron (Fe) and other inevitable impurities, wherein the amounts of carbon (C), silicon (Si) and aluminum (Al) satisfy the following mathematical relation (1). [Mathematical relation (1)] [C]+([Si]+[Al])/5≤0.35% (wherein [C], [Si] and [Al] respectively mean the wt % of C, Si and Al.)

An ultra low carbon interstitial free steel having an improved composition, wherein Ti+Nb+V is max 0.10 weight %. This steel has a very good ductility.

A sheet metal component made of a hot-formed flat steel product including a steel substrate consisting of, in mass. %, C: 0.1-0.4%, Mn: 0.5-3.0%, Si: 0.05-0.5% Cr: 0.005-1.0%, B: 0.0005-0.01% and optionally one or more of V, Ti, Nb, Al, Ni, Cu, Mo, and W, where the contents of the respective optionally present alloy element are V: 0.001-0.2%, Ti: 0.001-0.1%, Nb: 0.001-0.1%, Al: 0.01-0.2%, Ni: 0.01-0.4%, Co: 0.01-0.8% Mo: 0.001-1.0%, W: 0.001-1.0%, and the remainder iron and unavoidable impurities, wherein the unavoidable impurities include contents less than 0.1% P, less than 0.05% S, and less than 0.01% N, and an Al corrosion protection layer applied to the steel substrate, wherein the component is optionally hardened. An adhesive section having an SDR value of 3-30%, determined according to ISO 25178 is provided on the free outer face of the corrosion protection coating for adhering the sheet metal component to another component.