CN1793400A - Strength of extension 750-795 MPa grade double-phase steel plate and mfg. method thereof - Google Patents
Strength of extension 750-795 MPa grade double-phase steel plate and mfg. method thereof Download PDFInfo
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- CN1793400A CN1793400A CN 200510130898 CN200510130898A CN1793400A CN 1793400 A CN1793400 A CN 1793400A CN 200510130898 CN200510130898 CN 200510130898 CN 200510130898 A CN200510130898 A CN 200510130898A CN 1793400 A CN1793400 A CN 1793400A
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Abstract
The invention relates to a tensile strength 715-795MPa grade double phase steel sheet. Its chemical composition mass percent is as follows: 0.13-0.17%C, 0.20-0.40%Si, 1.30-1.50%Mn, 0.02-0.03%Nb, rest Fe. Thickness gauge is 3-4.5mm. And its form is fine grain ferrite and martensite double phase. The former volume faction is 80-85%. The latter is 20-15%. The former average grain size is 4um. The invention adopts rolling by rolling and cooling control method. The start rolling temperature is 1100-1150 centigrade degree. The final is 800-850 centigrade degree. The first segment cooling speed is 15-20 centigrade degree per second. The second is 270-310. The temperature after cooling is 620-650 centigrade degree. Winding temperature is 30-80 centigrade degree. Steel sheet thickness is 3-4.5mm.
Description
Technical field
The invention belongs to technical field of steel rolling, relate to the high-strength steel manufacturing technology of automobile structure, be specifically related to a kind of tensile strength 715～795MPa level dual phase sheet steel and manufacture method.
Background technology
High-strength vehicle is one of focus of domestic and international material work sutdy with the exploitation of hot-rolled steel sheet always.General ferrite+perlite hot-rolled steel sheet maximum strength of using is the 500MPa level, though micro alloying elements such as increase Nb or Ti can further improve intensity, plasticity is variation, thereby limited its application.For further improving intensity, developed dual phase steel (DP).Two-phase high-strength steel characteristics are the about 15% hard phases that distribute on tiny ferrite matrix, and further strengthen by the solid solution atom, and the tensile strength of ferrite-bainite and dual phase ferritic-martensitic steel is between 550～650MPa.Because the restriction of plasticity, dual phase steel can't reach 800MPa level level.For the requirement of satisfied more high strength and forming property, developed the 800MPa level three-phase TRIP steel that contains residual austenite again, the residual austenite strain-induced changes martensite (TRIP) in deformation process, when improving intensity, improves forming property.But the way of complex alloysization is adopted in the direct hot-rolled dual-phase steel that can commercially produce at present and the TRIP steel capital, has problems such as cost height, technology difficulty are big, is unfavorable for promoting, domestic still can not scale operation.Consider environmental problem and energy problem, it is steel (or add trace alloying element) that novel high-strength vehicle structural part will trend towards simple C-Si-Mn with the chemical ingredients of hot-rolled steel sheet; Develop controlled rolling and control cold novel process, comprehensive utilization refined crystalline strengthening and phase transformation strengthening mode improve the steel strength limit.
Summary of the invention
With the problem that hot-rolled steel sheet and production technique thereof exist, the invention provides a kind of tensile strength 715～795MPa level dual phase sheet steel and manufacture method at existing high-strength vehicle.
The invention provides a kind of tensile strength 715～795MPa level two-phase steel with fine crystal grain, its main chemical compositions by mass percent is: 0.13～0.17%C, 0.20～0.40%Si, 1.30～1.50%Mn, and 0.02～0.03%Nb, surplus is Fe.The present invention provides a kind of new structural state for 715～795MPa level hot rolled steel plate, that is: close grain ferrite and martensite duplex structure.Wherein: the ferrite volume fraction is 80～85%, and the martensite volume fraction is 20～15%, and the ferrite average grain size is 4 μ m.
The present invention adopt above-mentioned chemical ingredients, thickness is the steel billet of 80～250mm, by hot rolling and two sections quick process for cooling production tensile strength 715～795MPa level dual phase sheet steels, specifically carry out according to the following steps:
(1) steel billet is heated to 1150～1250 ℃, is incubated 2～2.5 hours.
(2) carry out hot rolling after the insulation, 1100～1150 ℃ of control start rolling temperatures, 800～850 ℃ of finishing temperatures.
(3) carry out the two-part controlled chilling after the hot rolling, control 15～20 ℃/s of first section speed of cooling, 620～650 ℃ of cooling back temperature; 270～310 ℃/s of second section speed of cooling, 30～80 ℃ of final cooling temperatures (being coiling temperature).
(4) batch 30～80 ℃ of coiling temperatures, control steel plate thickness 3～4.5mm after the cooling.
The present invention is by hot rolling and two sections quick process for cooling, and to obtain the thickness specification be 3～4.5mm, have the steel plate of close grain ferrite and martensite duplex structure.Wherein: the ferrite volume fraction is 80～85%, and the martensite volume fraction is 20～15%, and the ferrite average grain size is 4 μ m; Main mechanical property: yield strength 465～535MPa, tensile strength 715～795MPa, breaking elongation 21～24% has considerable intensity and plasticity over-all properties.
Description of drawings
Accompanying drawing is the present invention 715～795MPa level close grain ferrite/martensite dual phase sheet steel typical gold phase constitution photo.
Embodiment
Chemical ingredients steel shown in the option table 1 is a raw material, and billet size is 80mm (thick) * 70mm (wide) * 140mm (length).Implement cooling controlling and rolling controlling process on milling train, the rolling thickness specification is the steel plate of 3～4.5mm, technology for controlled cooling such as table 2, mechanical property with organize mark such as table 3.
Table 1 embodiment surveys chemical ingredients (massfraction %, surplus is Fe)
| The composition numbering | C | Mn | Si | Nb |
| DP0 | 0.15 | 1.5 | 0.2 | 0.02 |
| DP1 | 0.13 | 1.30 | 0.22 | 0.022 |
| DP2 | 0.17 | 1.47 | 0.36 | 0.024 |
| DP4 | 0.16 | 1.4 | 0.4 | 0.03 |
Table 2 embodiment surveys the process for cooling parameter
| Numbering | Heating temperature | Soaking time | Start rolling temperature | Finishing temperature | Leading portion cooling back temperature | The leading portion speed of cooling | Final cooling temperature | The back segment speed of cooling |
| (℃) | Hour | (℃) | (℃) | (℃) | (℃/s) | (℃) | (℃/s) | |
| DP0-1 | 1150 | 2 | 1100 | 800 | 650 | 16 | 50 | 280 |
| DP0-2 | 1180 | 2.5 | 1150 | 810 | 630 | 18 | 40 | 300 |
| DP1-1 | 1250 | 2.2 | 1120 | 850 | 650 | 20 | 30 | 310 |
| DP1-2 | 1200 | 2 | 1130 | 840 | 640 | 20 | 60 | 290 |
| DP2-1 | 1230 | 2.3 | 1140 | 820 | 620 | 20 | 80 | 270 |
| DP2-2 | 1210 | 2.1 | 1150 | 800 | 650 | 15 | 50 | 300 |
| DP4-1 | 1220 | 2.4 | 1150 | 830 | 625 | 15 | 80 | 280 |
| DP4-2 | 1160 | 2.5 | 1100 | 825 | 635 | 17 | 70 | 300 |
Table 3 embodiment mechanical property and tissue volume mark
| Numbering | Steel plate thickness | R e | R m | A t | R e/R m | R m×A t | Volume fraction | |
| F | M | |||||||
| (mm) | (MPa) | (MPa) | (％) | - | - | ％ | ％ | |
| DP1-1 | 4.5 | 465 | 715 | 23 | 0.65 | 16445 | 85 | 15 |
| DP1-2 | 4.4 | 532 | 795 | 24 | 0.67 | 19080 | 83 | 17 |
| DP2-1 | 3.0 | 495 | 760 | 24 | 0.65 | 18240 | 83 | 17 |
| DP2-2 | 4.4 | 535 | 795 | 21 | 0.67 | 16695 | 80 | 20 |
Wherein:
R
e: yield strength; R
m: tensile strength; A
t: breaking elongation; R
e/ R
m: yield tensile ratio; R
m* A
t: strength and ductility product; F: ferrite; M---martensite.
Claims (2)
1, a kind of tensile strength 715～795MPa level dual phase sheet steel, its main chemical compositions by mass percent is: 0.13～0.17%C, 0.20～0.40%Si, 1.30～1.50%Mn, 0.02～0.03%Nb, surplus is Fe; The thickness specification is 3～4.5mm, has close grain ferrite and martensite duplex structure, and wherein: the ferrite volume fraction is 80～85%, and the martensite volume fraction is 20～15%, and the ferrite average grain size is 4 μ m; Product yield strength 465～535MPa, tensile strength 715～795MPa, breaking elongation 21～24%.
2, the manufacture method of the described tensile strength 715～795MPa of claim 1 level dual phase sheet steel is characterized in that processing step and processing parameter are:
(1) steel billet with the described chemical ingredients of claim 1 is heated to 1150～1250 ℃, is incubated 2～2.5 hours;
(2) carry out hot rolling after the insulation, 1100～1150 ℃ of control start rolling temperatures, 800～850 ℃ of finishing temperatures;
(3) carry out the two-part controlled chilling after the hot rolling, control 15～20 ℃/s of first section speed of cooling, 620～650 ℃ of cooling back temperature; 270～310 ℃/s of second section speed of cooling, final cooling temperature are 30～80 ℃ of coiling temperatures;
(4) batch 30～80 ℃ of coiling temperatures, control steel plate thickness 3～4.5mm after the cooling.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101308985A CN100348767C (en) | 2005-12-27 | 2005-12-27 | Strength of extension 750-795 MPa grade double-phase steel plate and mfg. method thereof |
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| CNB2005101308985A CN100348767C (en) | 2005-12-27 | 2005-12-27 | Strength of extension 750-795 MPa grade double-phase steel plate and mfg. method thereof |
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| CN1793400A true CN1793400A (en) | 2006-06-28 |
| CN100348767C CN100348767C (en) | 2007-11-14 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103451523A (en) * | 2013-09-03 | 2013-12-18 | 辽宁科技大学 | Niobium-containing high-strength fine-grain 700MPa-level hot-rolled dual-phase steel and production method thereof |
| CN104060158A (en) * | 2013-09-12 | 2014-09-24 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot rolled dual phase steel and production method thereof |
| CN106011618A (en) * | 2016-06-06 | 2016-10-12 | 日照宝华新材料有限公司 | Method for producing DP780 steel based on ESP sheet billet continuous casting and rolling flow |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1017351B (en) * | 1988-07-16 | 1992-07-08 | 北京科技大学 | Thermal treatment method for making two-phase steel with fine crystal grain |
| JPH09241790A (en) * | 1996-03-07 | 1997-09-16 | Nippon Steel Corp | Hot rolled high strength steel plate of low yield ratio type, excellent in durability and fatigue characteristic, by continuous hot rolling process and its production |
| CN1045623C (en) * | 1996-06-20 | 1999-10-13 | 汤铁琴 | Bluing and low-carbon martensite heat treatment of high strength building steel bar |
| JP3253880B2 (en) * | 1996-12-27 | 2002-02-04 | 川崎製鉄株式会社 | Hot-rolled high-strength steel sheet excellent in formability and collision resistance, and method for producing the same |
| JP2001164337A (en) * | 1999-12-09 | 2001-06-19 | Nippon Steel Corp | High tensile strength steel excellent in delayed fracture characteristic and producing method therefor |
| JP2002129281A (en) * | 2000-10-23 | 2002-05-09 | Nippon Steel Corp | High tensile strength steel for welding structure excellent in fatigue resistance in weld zone and its production method |
| JP4470701B2 (en) * | 2004-01-29 | 2010-06-02 | Ｊｆｅスチール株式会社 | High-strength thin steel sheet with excellent workability and surface properties and method for producing the same |
| CN100351417C (en) * | 2004-04-08 | 2007-11-28 | 宝钢集团上海梅山有限公司 | Hot-rolling and low-carbon bainite composite phase material and preparation thereof |
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2005
- 2005-12-27 CN CNB2005101308985A patent/CN100348767C/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103451523A (en) * | 2013-09-03 | 2013-12-18 | 辽宁科技大学 | Niobium-containing high-strength fine-grain 700MPa-level hot-rolled dual-phase steel and production method thereof |
| CN104060158A (en) * | 2013-09-12 | 2014-09-24 | 攀钢集团攀枝花钢铁研究院有限公司 | Hot rolled dual phase steel and production method thereof |
| CN106011618A (en) * | 2016-06-06 | 2016-10-12 | 日照宝华新材料有限公司 | Method for producing DP780 steel based on ESP sheet billet continuous casting and rolling flow |
| CN106011618B (en) * | 2016-06-06 | 2018-07-03 | 日照宝华新材料有限公司 | Method based on ESP bar strip continuous casting and rolling flow paths production DP780 steel |
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| CN100348767C (en) | 2007-11-14 |
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