The present invention provides a method for producing a sheet. The method includes providing a substrate, depositing a metal coating over at least one surface by dipping the substrate in a bath in order to obtain the sheet, wiping the metal coating by means of at least one nozzle projecting through at least one outlet a wiping gas onto the metal coating, the sheet being run in front of the nozzle, the wiping gas being ejected from the nozzle along a primary direction of ejection (E), a confinement box delimiting a confined zone at least downstream of the zone of impact (I) of the wiping gas on the sheet and solidifying the metal coating. The method satisfying: $\frac{Z}{d}?12\mathrm{and}{f}_{O_2}?\frac{{10}^{-4}}{W^2}\left(0.63+\sqrt{0.4+94900*W^2}\right)\mathrm{with}W=\frac{\sqrt{\mathrm{PdZ}}}{V}.$

A method for producing high-strength galvannealed steel sheets having excellent workability and fatigue resistance. The method comprises subjecting a steel sheet to an oxidation treatment, the oxidation treatment including heating the steel sheet in an upstream stage at a temperature in the range of 400 C. to 750 C. in an atmosphere having an O.sub.2 concentration of not less than 1000 ppm by volume and a H.sub.2O concentration of not less than 1000 ppm by volume and a downstream stage at a temperature in the range of 600 C. to 850 C. in an atmosphere having an O.sub.2 concentration of less than 1000 ppm by volume and a H.sub.2O concentration of not less than 1000 ppm by volume. The method further comprises subjecting the steel sheet to reducing annealing, hot-dip galvanizing treatment and alloying treatment.

The present invention provides a hot-dip galvanized steel sheet that is excellent in plating wettability and plating adhesiveness even when a base steel sheet contains Si and Mn, and a manufacturing method of the same. The hot-dip galvanized steel sheet according to the present invention includes a base steel sheet containing Si, Mn, and other predetermined components, and a hot-dip galvanizing layer formed on at least one surface of the base steel sheet. In the base steel sheet, a value of H.sub.A representing average hardness in a surface layer ranging from an interface between the base steel sheet and the hot-dip galvanizing layer to 50 m in depth and a value of H.sub.B representing average hardness in a deep portion ranging from the interface to greater than 50 m in depth satisfy all the following three relational expressions.
50H.sub.A500(1)
50H.sub.B500(2)
0.5H.sub.A/H.sub.B0.9(3)

The present invention provides a deformed part created by forming a coated metal sheet into a part, the coated metal sheet comprising a steel substrate, at least one face of which is coated with a metal coating deposited by dipping the substrate in a bath, said coating comprising between 0.2 and 0.7% by weight of Al, the remainder of the metal coating being Zn and inevitable impurities, wherein an outer surface of a metal coating of the deformed part has a waviness Wa0.8 of less than or equal to 0.43 ?m.

A high-strength hot-dip galvanized steel sheet including a hot-dip galvanized plating layer on a steel sheet base material whose tensile strength is 590 MPa or more, wherein the plating layer includes projecting alloy layers being in contact with the steel sheet base material, a number density of the projecting alloy layers is 4 pieces/mm or more per unit length of an interface between the steel sheet base material and the plating layer when seen from a sectional direction, and a maximum diameter of the projecting alloy layers at the interface is 100 m or less, wherein the steel sheet base material includes: a miniaturized layer being directly in contact with the interface between the steel sheet base material and the plating layer; a decarburized layer being in contact with the miniaturized layer and existing on an inward side of the steel sheet base material; and an inner layer other than the miniaturized layer and the decarburized layer, and one kind or two kinds or more of oxides of Si and Mn are contained in layers of the miniaturized layer, the decarburized layer, and the projecting alloy layers.

A hot-dip galvanized steel sheet having a base steel sheet and a hot-dip galvanized layer, a ferrite phase is, by volume fraction, 50% or less in a range of ? thickness to ? thickness centered at a position of ? thickness from the surface of the base steel sheet, a hard structure is 50% or more, wherein the hot-dip galvanized steel sheet has the hot-dip galvanized layer in which Fe is 5.0% or less and Al is 1.0% or less, and columnar grains formed of a ? phase is 20% or more in an entire interface between the plated layer and the base steel sheet. On the surface of the base steel sheet, a volume fraction of a residual austenite is 3% or less.

A high-strength hot-dip coated hot-rolled steel sheet excellent in terms of surface appearance quality and coating adhesiveness and a method for manufacturing. The method includes performing hot rolling followed by pickling on steel to form a pickled steel sheet, the steel having a chemical composition containing, by mass %, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 1.0% or less, Mn: 0.3% or more and 2.5% or less, P: 0.08% or less, S: 0.02% or less, Al: 0.001% or more and 0.20% or less, and Fe and inevitable impurities. The method further includes performing rolling with a rolling reduction ratio of 1% or more and 10% or less, and a hot-dip coating treatment. The obtained steel sheet has an arithmetic average roughness Ra of 2.0 m or less on the surface of the steel sheet, and a tensile strength of 590 MPa or more.

A high-strength multi-phase steel having minimum tensile strengths of 750 M:Pa and preferably having a dual-phase microstructure for a cold- or hot-rolled steel strip, in particular for lightweight vehicle construction is disclosed. The high-strength multi-phase steel has improved forming properties and a ratio of yield point to tensile strength of at most 73%. The high-strength multi-phase steel includes in mass %: C?0.075 to ?0.105; Si?0.600 to ?0.800; Mn?1.000 to ?0.700; Cr?0.100 to ?0.480; Al?0.010 to ?0.060; N 0.0020?0.0120; S?0.0030; Nb?0.005 to ?0.050; Ti?0.0050 to ?0.050; B?0.0005 to ?0.0040; Mo?0.200; Cu?0.040%; Ni?0.040 % the remainder iron, including typical elements accompanying steel that are not mentioned above, which represent contamination resulting from smelting.

A high-formability, super-high-strength, hot-dip galvanized steel plate, the chemical composition of which comprises, based on weight percentage, C: 0.15-0.25 wt %, Si: 1.00-2.00 wt %, Mn: 1.50-3.00 wt %, P0.015 wt %, S0.012 wt %, Al: 0.03-0.06 wt %, N0.008 wt %, and the balance of iron and unavoidable impurities. The room temperature structure of the steel plate comprises 10-30% ferrite, 60-80% martensite and 5-15% residual austenite. The steel plate has a yield strength of 600-900 MPa, a tensile strength of 980-1200 MPa, and an elongation of 15-22%. Through an appropriate composition design, a super-high-strength, cold rolled, hot-dip galvanized steel plate is manufactured by continuous annealing, wherein no expensive alloy elements are added; instead, remarkable increase of strength along with good plasticity can be realized just by appropriate augment of Si, Mn contents in combination with suitable processes of annealing and furnace atmosphere control. In addition, the steel plate possesses good galvanization quality that meets the requirement of a super-high-strength, cold rolled, hot-dip galvanized steel plate for automobiles.

A method for the fabrication of a steel product is provided. The method includes the steps of characterizing a layer of oxides present on a running steel substrate which includes providing a portion of the steel substrate comprising a layer of oxides and the portion defines an oxide surface, collecting light (Lr) from the oxide surface using a hyperspectral camera (20) in order to obtain intensity values (I.sub.?,M) respectively representative of an intensity of a part (Lr.sub.?,M) of the collected light, each part being respectively collected from one of a plurality of points (M) located on the oxide surface and respectively has a wavelength (?) from a plurality of wavelengths, comparing the obtained intensity values with reference intensity values obtained for reference oxides, and calculating amounts of reference oxides in the layer. A device for characterizing a layer of oxides present on a steel substrate is also provided.