A coated steel substrate including a coating including nanographite having a lateral size between 1 and 60 m and a binder including sodium silicate or a binder including aluminum sulfate and an additive being alumina, wherein the steel substrate has the following compositions in weight percent: 0.31C1.2%, 0.1Si1.7%, 0.15Mn3.0%, P0.01%, S0.1%, Cr1.0%, Ni1.0%, Mo0.1%, and on a purely optional basis, one or more elements such as Nb0.05%, B0.003%, Ti0.06%, Cu0.1%, Co0.1%, N0.01%, V0.05%, the remainder of the composition being made of iron and inevitable impurities resulting from the elaboration and a method for the manufacture of the coated steel substrate.

A press-hardened automotive component having a first portion formed from a first steel alloy comprising between about 1.0 and 9.0 weight percent Chromium (Cr), between about 0.5 and 2.0 weight percent Silicon (Si), and between about 0.2 and 0.45 weight percent Carbon (C); and second portion formed from a second steel alloy comprising between about 1.0 and 9.0 weight percent Chromium (Cr), between about 0.5 and 2.0 weight percent Silicon (Si), and between about 0.01 and 0.25 weight percent Carbon (C). Each of the first steel alloy and second steel alloy further comprises between greater than 0.0 to about 3.0 weight percent Manganese (Mn), and between greater than 0.0 weight percent to less than about 0.01 weight percent Nitrogen (N). A laser weld interface joins the first steel alloy workpiece to the second steel alloy workpiece.

A method for the manufacture of a cold rolled, recovered TWIP steel sheet coated with a metallic coating is provided including the following steps: (A) the feeding of a slab having the following composition : 0.1<C<1.2%, 13.0Mn<25.0%, S0.030%, P0.080%, N0.1%, Si3.0%, and on a purely optional basis, one or more elements such as Nb0.5%, B0.005%, Cr1.0%, Mo0.40%, Ni1.0%, Cu5.0%, Ti0.5%, V2.5%, Al4.0%, 0.06Sn0.2%, the remainder of the composition making up of iron and inevitable impurities resulting from elaboration; (B) Reheating such slab and hot rolling it; (C) A coiling step; (D) A first cold-rolling; (E) A recrystallization annealing; (F) A second cold-rolling; and (G) A recovery heat treatment performed by hot-dip coating.

A cold rolled and annealed steel sheet includes by weight: 0.6<C<1.3%, 15.0Mn<35%, 6.0Al<15%, Si2.40%, S0.015%, P0.1%, N0.1%, optionally one or more elements chosen among Ni, Cr and Cu in an individual amount of up to 3% and optionally one or more elements chosen among B, Ta, Zr, Nb, V, Ti, Mo, and W in a cumulated amount of up to 2.0%, the remainder of the composition making up of iron and inevitable impurities resulting from elaboration, a microstructure of said sheet comprising at least 0.1% of intragranular kappa carbides, wherein at least 80% of said kappa carbides have an average size below 30 nm, optionally up to 10% of granular ferrite, the remainder being made of austenite, an average grain size of the austenite being below 6 m, an average aspect ratio of the austenite being between 1.5 and 6, an average grain size of the ferrite, when present being below 5 m, and an average aspect ratio of the ferrite, when present, being below 3.0.

The invention relates to a flat steel product for hot forming, consisting of a steel substrate which consists of a steel having 0.1-3 wt % of Mn and optionally up to 0.01 wt % of B, and of an Al-based protective coating applied to the steel substrate. The iron-free mass fraction in the protective coating of Mg as additional alloy constituent adds up to less than 2.50% Mg. In addition, the iron-free mass fraction in the protective coating of Mn as additional alloy constituent adds up to more than 0.30% Mn and the iron-free mass fraction in the protective coating of Si as additional alloy constituent adds up to less than 1.80%.

A process for manufacturing a non-stamped prealloyed steel coil, sheet or blank, comprising the following successive steps of: providing a non-stamped precoated steel coil, sheet or blank composed of a steel substrate covered by a precoating of aluminum, or aluminum-based alloy, or aluminum alloy, wherein the precoating thickness is comprised between 10 and 35 micrometers on each side of the steel coil, sheet or blank, then heating the non-stamped steel coil, sheet or blank in a furnace under an atmosphere containing at least 5% oxygen, up to a temperature ?.sub.1 comprised between 750 and 1000? C., for a duration t.sub.1 comprised between t.sub.1min and t.sub.1max, wherein: t.sub.1min=23500/(?.sub.1?729.5) and t.sub.1max=4.946?10.sup.41??.sub.1.sup.?13.08, t.sub.1 designating the total duration in the furnace, ?.sub.1 being expressed in ? C. and t.sub.1min and t.sub.1max being expressed in seconds, then cooling the non-stamped steel coil, sheet or blank at a cooling rate V.sub.r1 down to a temperature ?.sub.i, then maintaining the non-stamped steel coil, sheet or blank at a temperature ?.sub.2 comprised between 100 and 500? C., for a duration t.sub.2 comprised between 3 and 45 minutes, so to obtain a diffusible hydrogen less than 0.35 ppm.

This relates to a process for manufacturing a recovery annealed coated steel substrate for packaging applications and a packaging steel product produced thereby.

A non-stamped prealloyed steel coil, sheet or blank includes a heat-treatable steel substrate covered by an alloyed precoating containing aluminum and iron, aluminum not being present as free aluminum; and an interdiffusion layer at an interface between the steel substrate and the precoating, with a thickness between 2 and 16 micrometers, the interdiffusion layer being a layer with an (Fe) ferritic structure, having Al and Si in solid solution.

A graphene-coated steel sheet and a method for manufacturing the same are provided. The graphene-coated steel sheet includes a steel sheet and a graphene layer formed on the steel sheet. Therefore, the graphene-coated steel sheet can be useful in preventing corrosion of iron, such as oxidation of iron, and has remarkably excellent thermal conductivity and electrical conductivity, as well as excellent heat resistance resulting from thermal stability of graphene. Also, the method can be useful in manufacturing a high-quality graphene-coated steel sheet having a monocrystalline form and showing substantially no defects or impurities.

A method for producing a high strength coated steel sheet having a yield strength YS of at least 800 MPa, a tensile strength TS of >1180 MPa, a total elongation >14% and a hole expansion ratio HER>30%. The steel contains in weight %: 0.13%C0.22%, 1.2%Si1.8%, 1.8%Mn2.2%, 0.10%Mo0.20%, Nb0.05%, Al0.5%, the remainder being Fe and unavoidable impurities. The sheet is annealed at a temperature TA higher than Ac.sub.3 but less than 1000 C. for more than 30 s, then quenched by cooling temperature QT between 325 C. and 375 C., at a cooling speed sufficient to obtain a structure consisting of austenite and at least 60% of martensite, the austenite content being such that the fmal structure can contain between 3% and 15% of residual austenite and between 85 and 97% of the sum of martensite and bainite, without ferrite, then heated to a partitioning temperature PT between 430 C. and 480 C. and maintained at this temperature for a partitioning time Pt between 10 s and 90 s, then hot dip coated cooled to the room temperature. Coated sheet obtained.