A coated steel substrate including a coating comprising nanographite having a lateral size between 1 and 60 m and a binder, wherein the steel substrate has the following compositions in weight percent: 0.31C1.2%, 0.1Si1.7%, 0.15Mn1.1%, 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.

To improve the formability of dual phase steels, the martensite phase is tempered. It may form a ferrite-carbide structure. The tempering step occurs after martensite has been formed in the dual phase steel. The tempering step can occur in a box annealing step or it can be performed in a continuous fashion, such as on a continuous annealing, continuous tempering heat treating, or continuous coating line. The tempering step can further comprise a temper rolling on a temper mill after the heating step.

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 flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.

Warming a metastable steel after coating and before or during cold rolling suppresses the transformation of austenite to martensite, resulting in lower mill loads and higher amounts of reduction at similar loads. As-warm rolled steel has enhanced mechanical properties when compared to steel reduced the same amount by cold rolling at room temperature.

A flat steel product for hot forming may be produced from a steel substrate that includes a steel comprising 0.1-3% by weight Mn and up to 0.01% by weight B, along with a protective coating that is applied to the steel substrate. The protective coating may be based on Al and may contain up to 20% by weight of other alloy elements. Also disclosed are methods for producing such flat steel products, steel components, and methods for producing steel components. Absorption of hydrogen is minimized during heating necessary for hot forming. This is achieved at least in part through an alloy constituent of 0.1-0.5% by weight of at least one alkaline earth or transition metal in the protective coating, wherein an oxide of the alkaline earth or transition metal is formed on an outer surface of the protective coating during hot forming of the flat steel product.

Provided is a method for manufacturing an HPF part having excellent bending properties including: manufacturing a hot rolled steel sheet; coiling the hot rolled steel sheet within a range of 450 C. to 750 C. for a time satisfying Expression 1; cold rolling, annealing and then hot dip aluminum plating on the annealed steel sheet; heating the hot dip aluminum plated steel sheet to a temperature of 850 C. to 1000 C. and maintaining the hot dip aluminum plated steel sheet for a certain period of time; and hot forming the heated steel and cooling at a temperature within a range of 200 C. or lower at a cooling speed of 20 C./s to 1000 C./s at the same time to manufacture an HPF part, [Expression 1] 190,000[coiling temperature (CT)Time (min)]/2350,000, in the Relational Expression 1, Time refers to a time taken to reach 200 C. from coiling temperature.

A high-strength cold-rolled steel sheet having excellent ductility and stretch flangeability includes: a chemical composition consisting, in mass %, C: 0.06 to 0.3, Si: 0.6 to 2.5%, Mn: 0.6 to 3.5%, P: at most 0.1%, S: at most 0.05%, Ti: 0 to 0.08%, Nb: 0 to 0.04%, total of Ti and Nb: 0 to 0.10%, sol.Al: 0 to 2.0%, Cr: 0 to 1%, Mo: 0 to 0.3%, V: 0 to 0.3%, B: 0 to 0.005%, Ca: 0 to 0.003%, REM: 0 to 0.003% and the remainder of Fe and impurities; a microstructure having a main phase including at least 40 area % in total of martensite and/or bainite; and a texture in which proportion of an average X-ray intensity in an {100}<011> to {211}<011> orientations relative to an average X-ray intensity of a random structure not having a texture is less than 6.

A high-strength multi-phase steel having tensile strengths of no less than 580 MPa, preferably with a dual-phase structure for a cold-rolled or hot-rolled steel strip having improved forming properties, in particular for lightweight vehicle construction is disclosed, containing the following elements (contents in % by mass): C 0.075 to 0.105; Si 0.200 to 0.300; Mn 1.000 to 2.000; Cr 0.280 to 0.480; Al 0.10 to 0.060; P 0.020; Nb 0.005 to 0.025; N 0.0100; S 0.0050; the remainder iron, including conventional steel-accompanying elements not mentioned above.

The present invention relates to a self-collapsed protective coating composition and use thereof. In particular, the invention relates to a self-collapsed protective coating composition for hot stamping of steel material, which can protect the surface of steel material from oxide scale and provide ease for subsequent welding.