In the present invention, provided is a steel sheet having a predetermined chemical composition and a metallographic structure, in which A/B, which is a ratio of a length A of an interface between epitaxial ferrite and ferrite to a length B of an interface between the epitaxial ferrite and martensite in a cross section that is along a rolling direction and perpendicular to a surface of the steel sheet at a position of ¼ of a sheet thickness from the surface of the steel sheet is more than 1.5, a ratio of a major axis to a minor axis of the martensite is 5.0 or more, and a tensile strength is 980 MPa or more.

An equipment for the continuous hot dip-coating of a metal strip including an annealing furnace, a tank containing a liquid metal bath, a snout connecting the annealing furnace and the tank, through which the metal strip runs in a protective atmosphere and the lower part of the snout, the snout tip, is at least partly immersed in the liquid metal bath in order to define with the surface of the bath, and inside this snout, a liquid seal and a separate overflow attached/hold to the snout through fixings, the overflow including at least one tray, placed in the vicinity of the strip when entering the liquid metal bath and encompassed by the liquid seal.

A hot-dip coated steel product including: a steel product; and a coating layer including a Zn—Al—Mg alloy layer disposed on a surface of the steel product, in which the Zn—Al—Mg alloy layer includes a Zn phase, an Al phase, and a MgZn.sub.2 phase, and contains a Mg—Sn intermetallic compound phase in the Zn phase, and the coating layer has a chemical composition satisfying a predetermined average composition, a total area proportion of the Al phase and the MgZn.sub.2 phase is 70% or more, an area proportion of the Zn phase is 30% or less, an average value of cumulative circumferential lengths of the Al phase is less than 88 mm/mm.sup.2, and a total frequency in number of the Al phase having a circumferential length of 50 μm or more is less than 100.

Provided is a technique that can produce a hot dip Zn—Al—Mg-based alloy coated steel product with a good plating appearance, without the need for heating of a steel product prior to immersion in a hot dip plating bath. Flux (11) for hot dip Zn—Al—Mg-based alloy plating contains: ZnCl.sub.2; and a low-reactive chloride which has low reactivity with respect to Mg in a plating bath and contains at least two chlorides selected from the compound group consisting of alkali metal chlorides and alkaline-earth metal chlorides, and a composition of the ZnCl.sub.2 and the low-reactive chloride is adjusted so that a liquidus temperature of the flux is 450° C. or lower.

This coated steel member includes: a steel sheet substrate having a predetermined chemical composition; and a coating formed on a surface of the steel sheet substrate and containing Al and Fe, in which the coating has a low Al content region having an Al content of 3 mass % or more and less than 30 mass % and a high Al content region formed on a side closer to a surface than the low Al content region and having an Al content of 30 mass % or more, a maximum C content of the high Al content region is 25% or less of a C content of the steel sheet substrate, a maximum C content of the low Al content region is 40% or less of the C content of the steel sheet substrate, and a maximum C content in a range from an interface between the steel sheet substrate and the coating to a depth of 10 μm on a side of the steel sheet substrate is 80% or less of the C content of the steel sheet substrate.

To obtain a high-strength hot-dip galvanized steel sheet having excellent surface appearance even in the case where a steel strip containing Mn at a predetermined ratio or more to Si is subjected to hot-dip galvanizing treatment, a method of producing a hot-dip galvanized steel sheet using a continuous hot-dip galvanizing apparatus comprises: subjecting a steel strip to annealing, by conveying it in an annealing furnace; and subjecting the steel strip discharged from a cooling zone to hot-dip galvanizing using a hot-dip galvanizing line, to obtain a hot-dip galvanized steel sheet. The steel strip has a chemical composition containing, in mass %, Mn: 1.7% or more and 3.5% or less and Si: 0.2% or more and 1.05% or less and satisfying [Si]/[Mn]≤0.30. The chemical composition, a dew point of an atmosphere in the soaking zone, and a delivery temperature of the heating zone satisfy Formula (1).

A rolled steel sheet, for press hardening is provided, having a chemical composition where Ti/N>3.42, and the carbon, manganese, chromium and silicon contents satisfy: $2.6C+\frac{\mathrm{Mn}}{5.3}+\frac{\mathrm{Cr}}{13}+\frac{\mathrm{Si}}{15}\ge 1.1\%.$
The sheet has a nickel content Ni.sub.surf at any point of the steel in the vicinity of the surface over a depth Δ, such that: Ni.sub.surf >Ni.sub.nom, Ni.sub.nom denoting the nominal nickel content of the steel, and such that, Ni.sub.max denoting the maximum nickel content within Δ: $\frac{\left({\mathrm{Ni}}_{\max }+{\mathrm{Ni}}_{\mathrm{nom}}\right)}{2}\times \left(\Delta \right)\ge 0.6,$
and such that: $\frac{\left({\mathrm{Ni}}_{\max }-{\mathrm{Ni}}_{\mathrm{nom}}\right)}{\Delta }\ge 0.01$
and the surface density of all of the particles D.sub.i and the surface density of the particles D.sub.(>2 μm) larger than 2 micrometers satisfy, at least to a depth of 100 micrometers in the vicinity of the surface of said sheet:
D.sub.i+6.75 D.sub.(>2 μm) <270
D.sub.i and D.sub.(>2 μm) being expressed as number of particles per square millimeter, and said particles denoting all the oxides, sulfides, and nitrides, either pure or combined such as oxysulfides and carbonitrides, present in the steel matrix.

A hot-dip coated steel product including: a steel product; and a coating layer including a Zn—Al—Mg alloy layer disposed on a surface of the steel product, in which the Zn—Al—Mg alloy layer includes a Zn phase, an Al phase, and a MgZn.sub.2 phase, and contains a Mg—Sn intermetallic compound phase in the Zn phase, and the coating layer has a chemical composition satisfying a predetermined average composition, a total area proportion of the Al phase and the MgZn.sub.2 phase is 70% or more, an area proportion of the Zn phase is 30% or less, an average value of cumulative circumferential lengths of the Al phase is less than 88 mm/mm.sup.2, and a total frequency in number of the Al phase having a circumferential length of 50 μm or more is less than 100.

A steel sheet for the manufacture of a press hardened part is provided, having a composition of: 0.15%≤C≤0.22%, 3.5%≤Mn<4.2%, 0.001%≤Si≤1.5%, 0.020%≤Al≤0.9%, 0.001%≤Cr≤1%, 0.001%≤Mo≤0.3%, 0.001%≤Ti≤0.040%, 0.0003%≤B≤0.004%, 0.001%≤Nb≤0.060%, 0.001%≤N≤0.009%, 0.0005%≤S≤0.003%, 0.001%≤P≤0.020%. A microstructure has less than 50% ferrite, 1% to 20% retained austenite, cementite, such that the surface density of cementite particles larger than 60 nm is lower than 10{circumflex over ( )}7/mm.sup.2, and a complement of bainite and/or martensite, the retained austenite having an average Mn content of at least 1.1*Mn %. Press-hardened steel part obtained by hot forming the steel sheet, and manufacturing methods thereof.

Disclosed is a hot-stamping component, which includes a base steel plate; and a plated layer on the base steel plate and including a first layer, a second layer, and an intermetallic compound portion having an island shape in the second layer, wherein the first layer and the second layer are sequentially stacked, and an area fraction of the intermetallic compound portion with respect to the second layer is an amount of 20% to 60%.