Baoshan Iron & Steel Co., Ltd.

Yong Zhong

Li Ping Wang

Li Wang

Xinyan Jin

Shu Zhou

Weijun Feng

Guangkui Hu

Wei Xiong

Xiaoming He

Jianjun Zhi

Junjie Huang

Liyang Zhang

Yanglin Ke

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.

A hot dipped high manganese steel and a manufacturing method therefor. The high manganese steel comprises a steel base plate and a coating on the surface of the steel base plate. The core of the steel base plate is austenite. The surface layer of the steel base plate is a ferrite fine grain layer. The ferrite fine grain layer comprises an oxide of Al. Furthermore, the steel base plate of the hot dipped high manganese steel comprises, in mass percentages, 10 to 30% of Mn element, 1 to 2% of Al element, and 0.4 to 0.8% of C element. The manufacturing method comprises: 1) manufacturing strip steel; 2) primary annealing and acid washing; 3) secondary annealing and hot dipping.

Hot dipped high manganese steel and manufacturing method therefor

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.

Cold-rolled high-strength steel having tensile strength of not less than 1500 MPA and excellent formability, and manufacturing method therefor

A high-formability and super-strength cold-rolled steel sheet and a manufacturing method thereof. The weight percentage of its components is: C 0.15-0.25%, Si 1.00-2.00%, Mn 1.50-3.00%, P&#x2264;0.015%, S&#x2264;0.012%, Al 0.03-0.06%, N&#x2264;0.008%, and the rest are Fe and inevitable impurities. The manufacturing method comprises the following steps: 1) smelting and casting; 2) heating to 1170&#x2dc;1230&#xb0; C. and performing thermal insulation; 3) performing hot rolling, the finish rolling temperature being 880&#xb1;30&#xb0; C., and coiling at 550&#x2dc;650&#xb0; C.; and 4) performing acid washing, cold rolling, and annealing, the cold rolling reduction being 40-60%, annealing at 860-920&#xb0; C., and performing slow cooling to 690-750&#xb0; C. with the cooling rate of 3&#x2dc;10&#xb0; C./s; performing rapid cooling at 240&#x2dc;320&#xb0; C., with the cooling speed &#x2265;50&#xb0; C./s, then heating to 360&#x2dc;460&#xb0; C., and performing thermal insulation for 100&#x2dc;500 s to cool to the room temperature at last. Finally, a high-formability, low-rebound property and super-strength cold-rolled steel sheet with the yield strength of 600&#x2dc;900 MPa, the tensile strength of 980&#x2dc;1150 MPa, the elongation of 17&#x2dc;25% is obtained.

High-formability and super-strength cold-rolled steel sheet

A high-formability, super-high-strength, hot-dip galvanized steel plate, the chemical composition of which comprises, based on weight percentage, C: 0.15-0.25 wt %, Si: 1.00-2.00 wt %, Mn: 1.50-3.00 wt %, P&#x2264;0.015 wt %, S&#x2264;0.012 wt %, Al: 0.03-0.06 wt %, N&#x2264;0.008 wt %, and the balance of iron and unavoidable impurities. The room temperature structure of the steel plate comprises 10-30% ferrite, 60-80% martensite and 5-15% residual austenite. The steel plate has a yield strength of 600-900 MPa, a tensile strength of 980-1200 MPa, and an elongation of 15-22%. Through an appropriate composition design, a super-high-strength, cold rolled, hot-dip galvanized steel plate is manufactured by continuous annealing, wherein no expensive alloy elements are added; instead, remarkable increase of strength along with good plasticity can be realized just by appropriate augment of Si, Mn contents in combination with suitable processes of annealing and furnace atmosphere control. In addition, the steel plate possesses good galvanization quality that meets the requirement of a super-high-strength, cold rolled, hot-dip galvanized steel plate for automobiles.

High-formability and super-strength hot galvanizing steel plate and manufacturing method thereof

The present invention discloses a superstrength cold rolled weathering steel sheet, wherein the weight percentage of the chemical elements thereof are as follows: C: 0.05&#x2dc;0.16%; Mn: 1.00&#x2dc;2.20%; Al: 0.02&#x2dc;0.06%; Cu: 0.20&#x2dc;0.40%; Cr: 0.40&#x2dc;0.60%; Ti: 0.015&#x2dc;0.035%; P: less than 0.03%; and C+Mn/16 is more than 0.19% and less than 0.23%; the remainders thereof being Fe and other unavoidable impurities. The present invention also discloses a method of manufacturing said superstrength cold rolled weathering steel sheet, comprising the following stages: smelting, heating and preservation, hot rolling, coiling, pickling, cold rolling, continuous annealing and skin passing. The advantages of the superstrength cold rolled weathering steel sheet and the method of manufacturing the same are: high strength, i.e., the yield strength more than 700 MPa and the tensile strength more than 1000 MPa; excellent performance of atmosphere corrosion resistance; thin so as to meet the demand of reducing the thickness and weight thereof; good shape and surface quality.

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Shanghai, China

Yong Zhong