Baoshan Iron & Steel Co., Ltd.

Huanrong Wang

Wei Wang

Ana Yang

Jiansu Zhang

Zigang Li

Jianye Li

A'na Yang

Disclosed are a high-strength and high-toughness steel plate with an 800 MPa grade tensile strength and a method for manufacturing the same, the chemical composition of the steel plate in weight percentage being: C: 0.15-0.25%, Si: 1.0-2.0%, Mn: 1.2-2.0%, P&#x2264;0.015%, S&#x2264;0.005%, Al: 0.5-1.0%, N: &#x2264;0.006%, Nb: 0.02-0.06%, O&#x2264;0.003%, and the balance being Fe and other inevitable impurities, and 1.5%&#x2264;Si+Al&#x2264;2.5%. By adopting an isothermal heat treatment a high-strength and high-toughness steel plate with an 800 MPa grade tensile strength, which has a microstructure mainly including bainite ferrite and residual austenite, is obtained impact energy.

High-strength high-tenacity steel plate with tensile strength of 800 MPa and production method therefor

A 980 MPa-grade hot-rolled dual-phase steel and a manufacturing method therefor. The chemical components of the steel comprise, in percentage by weight, 0.10%-0.20% of C, 0.8%-2.0% of Si, 1.0%-2.0% of Mn, 0-0.02% of P, 0-0.005% of S, 0-0.003% of O, 0.02%-0.06% of Al, 0-0.006% of N, 0.01%-0.06% of Nb, 0.01%-0.05% of Ti, and the balance of Fe and inevitable impurities. In addition, the components need to meet the following relation: 0.05%&#x2264;Nb+Ti&#x2264;0.10. The microstructure of the steel is made of ferrite and martensite. The average grain size of the ferrite is 5-10 &#x3bc;m, and the equivalent grain size of the martensite is 15-20 &#x3bc;m. The yield strength of the steel is greater than or equal to 500 MPa, the tensile strength of the steel is greater than or equal to 980 MPa, and the ductility Ais greater than or equal to 12%; the steel has excellent strength, ductility and tenacity matching and a relatively low yield ratio, and can be applied to parts requiring good formability, high strength and reduced thickness, such as wheels.

980 MPa-grade hot-rolled dual-phase steel and manufacturing method therefor

A 980 MPa-grade hot-rolled ferrite bainite dual-phase steel and a manufacturing method therefor. The chemical components of the steel comprise, in percentage by weight, 0.15-0.30% of C, 0.8-2.0% of Si, 1.0-2.0% of Mn, 0-0.02% of P, 0-0.005% of S, 0-0.003% of O, 0.5-1.0% of Al, 0-0.006% of N, 0.01-0.06% of Nb, 0.01-0.05% of Ti, and the balance of Fe and inevitable impurities. In addition, the chemical components meet the following relations: 0.05%&#x2264;Nb+Ti&#x2264;0.10%, and 2.5&#x2264;Al/C&#x2264;5.0. The microstructure of the steel is made of ferrite and bainite. The average grain size of the ferrite is 5-10 &#x3bc;m, and the equivalent grain size of the bainite is less than or equal to 20 &#x3bc;m. The yield strength of the steel is greater than or equal to 600 MPa, the tensile strength of the steel is greater than or equal to 980 Mpa, and the ductility is greater than or equal to 15%.

980 MPa-grade hot-rolled ferritic bainite dual-phase steel and manufacturing method therefor

Disclosed is provided a low yield ratio and superhigh-strength hot-rolled Q&P steel and a method for manufacturing the same, having the following chemical composition in weight percentage: C: 0.2-0.3%, Si: 1.0-2.0%, Mn: 1.5-2.5%, P: &#x2264;0.015%, S: &#x2264;0.005%, Al: 0.5-1.0%, N: &#x2264;0.006%, Nb: 0.02-0.06%, Ti: &#x2264;0.03%, O: &#x2264;0.003%, and the balance being Fe and inevitable impurities. The manufacture method comprises a stepped cooling process to finally obtain the steel with a three-phase structure containing a certain volume fraction of proeutectoid ferrite; martensite; and residual austenite, and having an excellent comprehensive performance with a yield strength of &#x2265;600 MPa, a tensile strength of &#x2265;1300 MPa, a good elongation, and a low yield ratio. The obtained Q&P steel also shows an excellent match of high plasticity suitable for easy deformabilities and wear-resistances.

Low-yield-ratio ultra-high-strength hot-rolled QandP steel and production method therefor

A high-toughness hot-rolled high-strength steel with a yield strength of Grade 800 MPa with its chemical components, in weight percentages, being C 0.02-0.05%, Si&#x2264;0.5%, Mn 1.5-2.5%, P&#x2264;0.015%, S&#x2264;0.005%, Al 0.02-0.10%, N&#x2264;0.006%, Nb 0.01-0.05%, Ti 0.01-0.03%, 0.03%&#x2264;Nb+Ti&#x2264;0.06%, Cr 0.1%-0.5%, Mo 0.1-0.5%, B 0.0005-0.0025%, and the balance of Fe and unavoidable impurities, and a preparation method thereof. The present invention acquires, via direct quenching, an ultra-low carbon martensite structure with a yield strength of 800 Mpa and an impact energy of more than 100J under a temperature of &#x2212;80&#xb0; C.

High-toughness hot-rolling high-strength steel with yield strength of 800 MPa, and preparation method thereof

A 700 Mpa-level high-strength hot rolling Q&P steel and the method of manufacturing the same, which steel has the chemical compositions in weight percentage as follows: C: 0.15%&#x2dc;0.40%; Si: 1.0%&#x2dc;2.0%; Mn: 1.5%&#x2dc;3.0%; P: less than or equal to 0.015%; S: less than or equal to 0.005%; Al: 0.3%&#x2dc;1.0%; N: less than or equal to 0.006%; Ti: 0.005%&#x2dc;0.015%, the remainders being Fe; it having a yield strength of more than or equal to 700 Mpa, a tensile strength of more than or equal to 1300 Mpa and an elongation rate of more than 10%. Through reasonable design on the compositions and on the basis of the compositions of common C&#x2014;Mn steel, the present invention improves the content of Si to restrict the precipitation of cementite, performs the micro-Ti treatment to refine the austenite grains, and improves the content of Al to quicken the austenite transformation dynamics during the air cooling process; at the same time, combines the hot rolling process with the staged cooling process to obtain the structures of proeutectoid ferrite plus martensite plus retained austenite and reduces the cost of alloy elements substantially.

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Shanghai, China

Huanrong Wang