A hot-rolled strip steel product having a chemical composition consisting of, in terms of weight percentages (wt. %): 0.025%-0.070% C, 0%-1.10% Si, 0.50%-2.0% Mn, <0.020% P, <0.050% S, <0.010% N, 0%-0.60% Cr, 0%-0.20% Ni, 0%-0.25% Cu, 0%-0.20% Mo, 0%-0.15% Al, 0%-0.050% Nb, 0.020%-0.20-% V, 0.020%-0.15% Ti, 0%-0.0010% B, remainder Fe and inevitable impurities, wherein the strip steel product has a microstructure comprising of, in terms of volume percentages (vol. %), ferrite ≥90%, wherein the ferrite structure comprises 10%-50% quasi-polygonal ferrite and a reminder of ferrite structure is polygonal ferrite and/or bainite: and wherein the steel strip product has an average ferrite grain size of <10 μm, an average hole expansion ratio of ≥50%, a yield strength (Rp0.2%) longitudinal to rolling direction of ≥660 MPa and a tensile strength of ≥760 MPa.

A hot-rolled strip steel product is described having a chemical composition consisting of, in terms of weight percentages (wt. %): 0.030%-0.10% C, 0%-1.10% Si, 0.50%-2.0% Mn, <0.020% P, <0.010% S,<0.010% N, 0%-0.60% Cr, 0%-0.20% Ni, 0%-0.25% Cu, 0%-0.30% Mo, 0%-0.15% Al, 0%-0.10% Nb, 0.10%-0.30% V, <0.020% Ti, 0%-0.0010% B, remainder being Fe and inevitable impurities, wherein the hot rolled strip steel product has a a microstructure comprising, in terms of volume percentages (vol. %), ferrite≥90, wherein the ferrite structure comprises bainite, at least 50% of polygonal ferrite and at most 10% quasi-polygonal ferrite, and wherein the steel strip product has an average hole expansion ratio≥50%, a yield strength (Rp0.2%) longitudinal to rolling direction of ≥660 MPa and a tensile strength≥760 MPa.

The present invention relates to a coated steel sheet having a thin aluminium alloy coating and a coating method thereof The coated steel sheet of the present invention is used for hot stamping. The coating thickness of the coated steel sheet is 5˜14 μm, wherein the aluminium alloy coating comprises a FeAlSi inhibitive layer adjacent to a substrate steel sheet and an Al alloy layer outside the FeAlSi inhibitive layer, wherein the thickness of the FeAlSi inhibitive layer is no more than 60% of the coating thickness and is 1.5˜6.0 μm. The diameters of Kirkendall voids within 2 μm from an interface between the FeAlSi inhibitive layer and the substrate steel to the interior of the substrate steel are no more than 2.5 μm, wherein the number of Kirkendall voids with a diameter of no less than 0.5 μm and no more than 2.5 μm does not exceed 15 per 35 μm. The present invention also discloses a coating method for coating a thin aluminium alloy coating on a substrate steel sheet for hot stamping. It can eliminate skip coating and enable a hot stamped component obtained by the coated steel sheet to have excellent resistance spot welding performance.

Method of hot press forming an article from zinc or zinc alloy coated steel, wherein the steel is a product obtained by: casting the molten steel into slabs; reheating the slabs; hot rolling the steel into a strip, preferably with an FRT above Ar3; coiling the hot rolled steel strip; pickling the hot rolled steel strip; continuous annealing the strip; hot dip coating the steel strip with the zinc or zinc alloy whilst: using a dipping time of 3 seconds or more; maintaining in the hot dip bath a bath temperature of 420° C. to 500° C.; wherein the zinc bath contains essentially zinc, at least 0.1% Al, and optionally up to 5% Al and optionally up to 4% Mg, the rest of the bath including further elements all individually less than 0.3%, and unavoidable impurities; hot press forming the article.

The invention relates to a process for producing an at least partly quenched and tempered sheet steel component, where the process comprises the following steps: providing a sheet steel, at least partly austenitizing the sheet steel at a temperature of at least Ac1, at least partly hardening the at least partly austenitized sheet steel to give an at least partly hardened sheet steel component, where the at least partly austenitized sheet steel is cooled to a temperature below Ms, at least partly annealing the at least partly hardened sheet steel component at a temperature of less than Ac1 for producing an at least partly quenched and tempered sheet steel component. A further subject of the invention is an at least partly quenched and tempered sheet steel component.

A high-strength cold-rolled steel sheet comprises: a chemical composition that contains C, Si, Mn, P, S, N, Al, Ti, Nb, and B with a balance consisting of Fe and inevitable impurities, and satisfies [mol % N]/[mol % Ti]<1; and a steel microstructure in which: an area fraction of ferrite is 30% or more and 60% or less; a total area fraction of tempered martensite and bainite is 35% or more and 65% or less; an area fraction of quenched martensite is 15% or less; an area fraction of retained austenite is 1% or more and 10% or less; an area fraction of low-Mn ferrite having a Mn concentration of 0.8×[% Mn] or less is 5% or more and 40% or less; a result of subtracting the area fraction of the low-Mn ferrite from the area fraction of the ferrite is 10% or more; an area fraction of a residual microstructure is less than 3%; and an average grain size of the low-Mn ferrite is 10 μm or less.

Disclosed in the present invention is a manufacturing method for a carbon steel and austenitic stainless-steel rolling clad plate, comprising the steps of: (1) obtaining a blank material of a carbon steel layer and a blank material of a stainless-steel layer; (2) assembling blank materials; (3) cladding and rolling; (4) cold rolling; (5) first annealing; and (6) second annealing. The carbon steel and austenitic stainless-steel rolling clad plate has two unique annealing processes, so that the clad plate has the performance advantages of the austenitic stainless-steel and the carbon steel. In addition, further disclosed in the present invention is a carbon steel and austenitic stainless-steel rolling clad plate manufactured by this method.

Disclosed are thermoformed component having excellent coating adhesion and a method for manufacturing the same. The thermoformed component comprises a substrate layer and an aluminum coating coated on at least one surface of the substrate layer, wherein the average roughness Ra of a surface of the thermoformed component is between 1.0 μm and 3.0 μm, the peak height and the peak-to-valley height Rt are between 8 μm and 30 μm, and the roughness peak count Rpc is greater than or equal to 50. The thermoformed component has good paintability, good coating adhesion and good corrosion resistance, and is very suitable for automotive parts.

A high-performance thermoformed component provided with a coating, and a manufacturing method therefor. The thermoformed component comprises a substrate and a coating thereon. The substrate comprises the following ingredients in percentage by weight: 0.01-0.8% of C, 0.05-1.0% of Si, 0.1-5% of Mn, 0.001-0.3% of P, 0.001-0.1% of S, 0.001-0.3% of Al, 0.001-0.5% of Ti, 0.0005-0.1% of B, 0.001-0.5% of Nb, 0.001-0.5% of V, and the remainder being Fe and other unavoidable impurities. The appearance of the thermoformed component has no color difference and no mottling. The surface oxygen content of the thermoformed component is 0.1-20 wt. %, and the ratio of the standard deviation to the average value of the surface oxygen content satisfies: 0<standard deviation of oxygen content/average value of oxygen content ≤0.3. In the manufacturing method, a coated steel plate that has undergone heat treatment, transfer processing, and hot stamping is not treated with oil.

A high-performance thermoformed component provided with a coating, and a manufacturing method therefor. The thermoformed component comprises a substrate and a coating thereon. The substrate comprises the following ingredients in percentage by weight: 0.01-0.8% of C, 0.05-1.0% of Si, 0.1-5% of Mn, 0.001-0.3% of P, 0.001-0.1% of S, 0.001-0.3% of Al, 0.001-0.5% of Ti, 0.0005-0.1% of B, 0.001-0.5% of Nb, 0.001-0.5% of V, and the remainder being Fe and other unavoidable impurities. The appearance of the thermoformed component has no color difference and no mottling. The surface oxygen content of the thermoformed component is 0.1-20 wt. %, and the ratio of the standard deviation to the average value of the surface oxygen content satisfies: 0<standard deviation of oxygen content/average value of oxygen content ≤0.3. In the manufacturing method, a coated steel plate that has undergone heat treatment, transfer processing, and hot stamping is not treated with oil.