A press hardening method includes the following steps providing a carbon steel sheet coated with a barrier pre-coating including nickel and chromium wherein the weight ratio Ni/Cr is between 1.5 and 9, cutting the sheet to obtain a blank, thermal treatment of the blank in an atmosphere having an oxidizing power equal or higher than that of an atmosphere consisting of 1% by volume of oxygen and equal or smaller than that of an atmosphere consisting of 50% by volume of oxygen, such atmosphere having a dew point between −30 and +30° C., transfer of the blank into a press tool, hot-forming of the blank to obtain a part, cooling of the part to obtain a microstructure in steel being martensitic or martensito-bainitic or made of at least 75 wt. % of equiaxed ferrite, from 5 to 20 wt. % of martensite and bainite in amount less than or equal to 10 wt. %.

The present invention provides a rolled steel sheet, for press hardening, for which the chemical composition includes, with contents expressed by weight, 0.24%≦C≦0.38%, 0.40%≦Mn≦3%, 0.10%≦Si≦0.70%, 0.015%≦Al≦0.070%, 0%≦Cr≦2%, 0.25%≦Ni≦2%, 0.015%≦Ti≦0.10%, 0%≦Nb≦0.060%, 0.0005%≦B≦0.0040%, 0.003%≦N≦0.010%, 0.0001%≦S≦0.005%, 0.0001%≦P≦0.025%, it being understood that the titanium and nitrogen content satisfy: Ti/N>3.42, and that the carbon, manganese, chromium and silicon content satisfy:

[00001]$2.6.Math..Math.C+\frac{\mathrm{Mn}}{5.3}+\frac{\mathrm{Cr}}{13}+\frac{\mathrm{Si}}{15}\ge 1.1.Math.\%,$

with the chemical composition optionally including one or more of the following elements: 0.05%≦Mo≦0.65%, 0.001%≦W≦0.30%, 0.0005%≦Ca≦0.005%, with the remainder made up of iron and inevitable impurities coming from preparation. The sheet includes a nickel content Ni.sub.surf at any point of the steel near the surface of said sheet over a depth Δ, such that Ni.sub.surf>Ni.sub.nom, where Ni.sub.nom designates the nominal nickel content of the steel, and such that Ni.sub.max designates the maximum nickel content within Δ:

[00002]$\frac{\left({\mathrm{Ni}}_{\max }+{\mathrm{Ni}}_{\mathrm{nom}}\right)}{2}\times \left(\Delta \right)\ge 0.6$

and such that:

[00003]$\frac{\left({\mathrm{Ni}}_{\max }+{\mathrm{Ni}}_{\mathrm{nom}}\right)}{\Delta }\ge 0.01,$

with the depth Δ expressed in microns and the Ni.sub.max and Ni.sub.nom contents expressed in percentages by weight.

Provided is an alloy-plated steel material that can be used in home appliances, automobiles, and construction materials and the like and, more particularly, to an alloy-plated steel material having excellent corrosion resistance and high surface quality.

A painted steel part includes a steel sheet precoated with a metallic coating and hot formed, the coating including: 2.0 to 24.0% by weight of zinc; 1.1 to 7.0% by weight of silicon; optionally from 0.5 to 3.0% by weight of magnesium when the amount of silicon is between 1.1 and 4.0%, and optionally additional elements chosen from Pb, Ni, Zr or Hf, a content by weight of each additional element being less than 0.3% by weight, a balance being aluminum, unavoidable impurities and residual elements resulting from feeding ingots or from a passage of the steel sheet in a molten bath; and a ratio Al/Zn by weight greater than 2.9; and a paint layer.

Provided is a zinc alloy-plated steel material used in automobiles, building materials, home appliances, or the like, and more specifically, to a zinc alloy-plated steel material having excellent corrosion resistance and surface quality, and a method for producing same.

Provided is an Al or Al alloy-coated stainless steel sheet having a coating substrate and a hot-dip Al or Al alloy coated layer provided on a surface of the coating substrate, the coating substrate having a predetermined chemical composition, the Mo content and W content of the chemical composition of the coating substrate, the thickness of the coating substrate, and the thickness of the hot-dip Al or Al alloy coated layer satisfying predetermined relations.

In a component made of press-form-hardened, aluminium-based coated steel sheet, the coating has a covering which contains aluminum and silicon applied in the hot-dip process. The press-form-hardened component in the transition region between steel sheet and covering has an inter-diffusion zone I, wherein, depending on the layer application of the covering before heating and press hardening, the thickness of the inter-diffusion zone I obeys the following formula: I [μm]<(1/35)×application on both sides [g/m.sup.2]+(19/7). Formed on the inter-diffusion zone I is a zone having various intermetallic phases having an average total thickness between 8 and 50 μm, on which zone there is in turn arranged a covering layer containing aluminum oxide and/or hydroxide having an average thickness of at least 0.05 μm to at most 5 μm.

There is provided a hot-stamped body including: a steel base metal; and a metallic layer formed on a surface of the steel base metal, wherein the metallic layer includes: an interface layer that contains, in mass %, Al: 30.0 to 36.0%, has a thickness of 100 nm to 5 μm, and is located in an interface between the metallic layer and the steel base metal; and a principal layer that includes coexisting MgZn.sub.2 phases and insular FeAl.sub.2 phases, is located on the interface layer, and has a thickness of 3 μm to 40 μm.

Provided is a plated steel sheet having both strength and workability. In a hot-dip Zn—Al—Mg-based plated steel sheet, the steel substrate contains C in an amount of 0.050 to 0.180% by mass, Si in an amount of 0.001 to 0.50% by mass, Mn in an amount of 1.00 to 2.80% by mass, Ti in an amount of 0.01 to 0.10% by mass, and B in an amount of 0.0005 to 0.0100% by mass, an average grain size of cementite after winding in a hot rolling step is not greater than 2 μm, a metal structure after a continuous hot-dip galvanizing step includes a ferrite phase and not less than 15 and less than 45% by area of a second phase, and the second phase is composed of martensite or composed of martensite and bainite and has an average crystal grain size of not greater than 8 μm.

Provided is a plated steel material which can be used for an automobile, a household appliance, a building material, and the like and, more specifically, to a zinc alloy plated steel material having excellent surface quality and corrosion resistance, and a method for manufacturing the same.