Baoshan Iron & Steel Co., Ltd.

Ironovation Materials Technology Co., Ltd.

Shu Zhou

Li Ping Wang

Li Wang

Hongliang Yi

Xiaochuan Xiong

Yong Zhong

Xinyan Jin

Guodong Wang

Dapeng Yang

Huajie Qin

Zeran Hou

Pre-coated steel sheet with aluminum or aluminum alloy pre-coating, manufacturing method and hot stamped components, where the method for manufacturing a pre-coated steel sheet with aluminum or aluminum alloy pre-coating relates to the situation of 0.10%≤C≤0.30%, the dew point of the mixed atmosphere is controlled in the range of −40˜−15° C. and, where it relates to the situation of 0.30%<C≤0.50%, the dew point of the mixed atmosphere is controlled in the range of −36˜−12° C. A pre-coated steel sheet with aluminum or aluminum alloy pre-coating is obtained by the method and hot stamping components are obtained by the pre-coated steel sheet. The improved toughness and VDA peak force are achieved for the hot stamping components and then the collision safety of hot stamping components is elevated.

Pre-coated steel sheet with aluminum or aluminum alloy pre-coating, manufacturing method and hot stamped components

Coated steel sheet used for hot stamping has a thin aluminium alloy coating with coating thickness of 5˜14 μm. The aluminium alloy coating has a FeAlSi inhibitive layer adjacent to a substrate steel sheet and an Al alloy layer outside the FeAlSi inhibitive layer. The thickness of the FeAlSi inhibitive layer is no more than 60% of the coating thickness and is 1.5˜6.0 μm. 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, and 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 coating method eliminates skip coating and resulting hot stamped component has excellent resistance spot welding performance.

Coated steel sheet with thin aluminium alloy coating and coating method thereof

Provided in the present disclosure is a method of heat treating a high-strength steel, wherein the high-strength steel comprises, by weight: 0.30-0.45% C, 1.0% or less Si, 0.20-2.5% Mn, 0.20-2.0% Cr, 0.15-0.50% Mo, 0.10-0.40% V, 0.2% or less Ti, 0.2% or less Nb, and a balance of Fe and other alloy elements and impurities, wherein the above alloy elements make Eq(Mn) according to the following formula (1) no less than 1.82, which method comprises the steps of 1) austenitizing; 2) carbide precipitation; and 3) tempering. The heat-treated steel in accordance with the present invention has high strength, high ductility and high toughness at the same time, especially improved reduction in area of tensile sample, so that it is particularly suitable for preparing spring members for vehicle suspension.Eq(Mn)=Mn+0.26Si+3.50P+1.30Cr+2.67Mo  (1)

Method of heat treating a high strength steel and a product obtained therefrom

A cold-rolled high-strength steel plate having excellent phosphating performance and formability and a manufacturing method therefor. The chemical composition of the steel plate is, in percentage by weight, C-%, Si-%, Mn-%, P&#x2264;%, S&#x2264;%, Al-%, N&#x2264;%, the remainder being Fe and impurities. The surface layer of the steel plate has an inner oxide layer with a thickness of-&#x3bc;m, and there is no enrichment of Si and Mn on the surface of the steel plate. The steel plate has tensile strength of &#x2265;MPa and an elongation of &#x2265;%. The structure at the room temperature contains retained austenite, ferrite, and martensite and/or bainite.

Cold-rolled high-strength steel plate having excellent phosphating performance and formability and manufacturing method therefor

A cold-rolled steel plate () and a manufacturing method therefor. The chemical composition of the steel plate () in percentage by weight is: C 0.15-0.25%, Si 1.50-2.50%, Mn 2.00-3.00%, P&#x2264;0.02%, S&#x2264;0.01%, Al 0.03-0.06%, N&#x2264;0.01%, with the balance being Fe and impurities. The surface layer has an inner oxide layer () with a thickness of 1-5 &#x3bc;m, and there is no enrichment of Si or Mn on the surface. The steel plate () has good phosphating performance and formability, with a tensile strength of &#x2265;1180 MPa and an elongation of &#x2265;14%, and has a complex-phase structure of ferrite, martensite, and retained austenite, the content of the retained austenite being not lower than 5%. A dew point is at &#x2212;25&#xb0; C. to 10&#xb0; C. in continuous annealing, such that external oxidation transitions to internal oxidation.

Provided is a cold-rolled high-strength steel having a tensile strength of not less than 1500 MPa and an excellent formability, the chemical elements thereof having the following mass percent ratios: 0.25%-0.40% of C, 1.50%-2.50% of Si, 2.0%-3.0% of Mn, 0.03%-0.06% of Al, P&#x2264;0.02%, S&#x2264;0.01%, N&#x2264;0.01% and at least one of 0.1%-1.0% of Cr and 0.1%-0.5% of Mo, with the balance being Fe and other unavoidable impurities. The microstructure of the cold-rolled high-strength steel has 5%-20% of residual austenite and 70%-90% of martensite, and the carbon concentration ratio of the residual austenite to the martensite is greater than 3.5 and less than 15. The cold-rolled high-strength steel sheet has a high strength and an excellent formability through a rational ingredient design and microstructure control.

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Shanghai, China

Shu Zhou