A metal mask material for OLED use reduced in amount warpage due to etching, a method for manufacturing the same, and a metal mask are provided. The metal mask material and metal mask of the present invention contain, by mass %, Ni: 35.0 to 37.0% and Co: 0.00 to 0.50%, have a balance of Fe and impurities, have thicknesses of 5.00 μm or more and 50.00 μm or less, and have amounts of warpage defined as maximum values in amounts of rise of four corners of a square shaped sample of the metal mask material of 100 mm sides when etching the sample from one surface until the thickness of the sample becomes ⅖ and placing the etched sample on a surface plate of 5.0 mm or less.

A method for manufacturing thin-specification high-Ti wear-resistant steel NM450 comprises the steps of preparing melted iron in a blast-furnace, preprocessing the melted iron, smelting the melted iron in a converter, refining the melted steel in a LF furnace, refining the melted steel in a RH furnace, conventional slab continuous casting, heating the slab in a heating furnace, dephosphorizing the slab by high-pressure water, heating the slab in a hot continuous rolling mill, performing ultra fast cooling, reeling, flattening, heating, quenching, tempering and finishing.

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.

A low-strength steel sheet for hot stamping according to an aspect of the present invention satisfies a predetermined chemical composition, the Ac.sub.3 point (° C.) represented by Equation (1) is 890° C. or more, and an area ratio of ferrite at a depth to be ¼ of a steel sheet thickness is 80% or more. Ac.sub.3 point (° C.)=910−203×[C].sup.1/2+44.7×[Si]−30×[Mn]+700×[P]+400×[Al]+400×[Ti] . . . (1) In Equation (1), [C], [Si], [Mn], [P], [Al], and [Ti] are values denoting the percentage contents of C, Si, Mn, P, Al, and Ti in terms of % by mass, respectively.

Provided is a steel sheet which is suitably used for an automobile structural member, etc., and more specifically, to: a steel sheet having excellent uniform elongation and strain hardening rate, while having high strength; and a method for producing same.

Provided are a high-strength steel sheet and a method for manufacturing same, the high-strength steel sheet including: an alloy system having C, Si, Mn, Cr, Al, Nb, Ti, B, P, S, N, and the remainder of Fe and other inevitable impurities. The contents of C, Si, and Al satisfy equation (1) below. The microstructure includes, by an area fraction, greater than 50% to 70% or less of tempered martensite, and the remainder of residual austenite, fresh martensite, ferrite, and bainite, in which a cementite phase as a second phase is precipitated and distributed in an area fraction of 1-3% between bainite laths, or at a lath on the tempered martensite or grain boundaries. [Equation (1)] [C]+([Si]+[Al])/5≤0.35 wt. % (wherein [C], [Si], and [Al] denote wt % of C, Si, and Al, respectively.)

A high-strength galvanized steel sheet includes a steel sheet having a steel composition having a specific component composition, a steel structure containing martensite and bainite at more than or equal to 70% (including 100%), ferrite at less than 20% (including 0%), and retained austenite at less than 5% (including 0%) in terms of area ratio, the amount of diffusible hydrogen in steel being less than or equal to 0.20 mass ppm; and a galvanizing layer provided on a surface of the steel sheet, having a content amount of Fe of 8 to 15% in mass %, and having an coating weight per one surface of 20 to 120 g/m.sup.2, wherein the amount of Mn oxides contained in the galvanizing layer is less than or equal to 0.050 g/m.sup.2, and a tensile strength is more than or equal to 1100 MPa and a yield ratio is more than or equal to 0.85.

A high-strength steel sheet includes a predetermined chemical composition, a microstructure contains, by volume percentage, 80% or more of tempered martensite, and a remainder consists of ferrite and bainite, the microstructure contains 5.0×10.sup.11 pieces/mm.sup.3 or more of, per unit volume, precipitate containing Ti and having an equivalent circle diameter of 5.0 nm or less, Hvs/Hvc which is a ratio of an average hardness Hvs at a position of a depth of 20 μm from a surface to an average hardness Hvc at a position of 0.20 to 0.50 mm from the surface is 0.85 or more, and the tensile strength is 1,180 MPa or more.

A steel sheet has a predetermined chemical composition, in which a metallographic structure in a surface layer region ranging from a surface to a position of 20 μm from the surface in a sheet thickness direction consists of ferrite and a secondary phase having a volume fraction of 1.0% to 15.0%, the metallographic structure in an internal region ranging from a position of more than 20 μm from the surface in the sheet thickness direction to a ¼ thickness position from the surface in the sheet thickness direction consists of ferrite and a secondary phase having a volume fraction of 5.0% to 25.0%, the volume fraction of the secondary phase in the surface layer region is less than the volume fraction of the secondary phase in the internal region, and in the surface layer region, the average grain size of the secondary phase is 0.5 μm to 4.0 μm, and a texture in which an X.sub.ODF{001}/{111} as the ratio of the intensity of {001} orientation to an intensity of {111} orientation in the ferrite is 0.70 to 2.50 is included.

The invention relates to a method for producing an ultra-high-strength hot-rolled structural steel, wherein a steel is produced with a carbon content that is not greater than 0.2%, wherein in order to avoid a diffusive transformation of the austenite, a sufficient transformation delay is achieved through the addition of manganese, chromium, and boron, and wherein the steel material is cast in a known way and the cast material is subjected to a temperature increase for purposes of the hot-rolling, wherein the strip is direct hardened immediately after the rolling process, wherein the martensite structure forms from the deformed austenite, and the material that has been produced in this way is then mechanically straightened in order to produce mobile dislocations, wherein the material is then annealed in order to adjust the desired elastic limit or yield strength while at the same time preserving the tensile strength, toughness, and forming properties that are present after the direct hardening, wherein the annealing temperature is between 100 and 200° C.