CN102766812A - 700 MPa hot-rolled dual phase steel plate with low yield ratio and manufacture method thereof - Google Patents
700 MPa hot-rolled dual phase steel plate with low yield ratio and manufacture method thereof Download PDFInfo
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- CN102766812A CN102766812A CN2012102030604A CN201210203060A CN102766812A CN 102766812 A CN102766812 A CN 102766812A CN 2012102030604 A CN2012102030604 A CN 2012102030604A CN 201210203060 A CN201210203060 A CN 201210203060A CN 102766812 A CN102766812 A CN 102766812A
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Abstract
The present invention relates to a 700MPa hot-rolled dual phase steel plate low yield ratio and a manufacture method thereof. The hot-rolled dual phase steel plate comprises, by weight, 0.06%-0.09% of C, 1.0%-1.2% of Si, 1.10%-1.30% of Mn, 0.020%-0.050% of Al, 0.4%-0.6% of Cr and the balance of Fe. The manufacture method comprises the following steps: (1) heating a billet by a heating furnace; (2) taking the billet out of the heating furnace, and rolling the billet by a hot continuous rolling machine; (3) carrying out subsection cooling by a laminar cooling process after rolling; and (4) coiling.
Description
Technical field
The present invention relates to metallic substance, relate to continuously hot rolling metal plate and belt technical field, relate to the plow-steel manufacturing of automobile structure, be specifically related to a kind of tensile strength 700MPa low yield strength ratio hot rolling biphase plate and method of manufacture thereof.
Background technology
Development and application high-strength vehicle steel plate materials is to realize one of light-weighted major measure of automobile; General low-alloy high-strength steel mainly adopts the ferritic+pearlitic structure material of microalloy elements such as single or compound interpolation Nb, V, Ti; Along with the raising of intensity, the forming property of material reduces, particularly when tensile strength reaches 700MPa; The material yield tensile ratio is also up to more than 0.80; Not only the grinding tool load is high, loss is big, and stamping parts cracking ratio is very high, is difficult to satisfy the forming requirements that automobile factory produces in batches.Hot-rolled dual-phase steel is main with the martensitic stucture of disperse distribution about 20% on the ferrite matrix; Have low yield tensile ratio and high work hardening and baking and hardening performance; It is smooth that low ys helps drawing, and high work hardening and baking hardening make the finished product have very high intensity.Well satisfying the composite request of automotive material HS high formability ability, is the good automobile strong material of application prospect.
Hot-rolled dual-phase steel is mainly controlled the control that ferritic and martensite biphase proportion of composing are realized the dual phase steel mechanical property through chemical ingredients and technology; The control fraction of martensite volume is the key that obtains desirable mechanical property with the appearance of avoiding perlite and bainite; Usually the fluctuation of the selection of chemical ingredients and technology is very big to the influence of hot-rolled dual-phase steel mechanical property, so the stable control of hot-rolled dual-phase steel tissue and mechanical property is the maximum difficult point that hot-rolled dual-phase steel is produced always.Can production tensile strength 600MPa (ZL 200610045846.2) and the hot-rolled dual-phase steel of 540MPa (ZL 200610045847.7) with the C-Mn-Si set member.But more the hot-rolled dual-phase steel of high intensity levels adopts usually and adds more valuable alloy.For example; Disclosure of the Invention CN 101279330A reaches 700MPa through adding 0.050%Nb or 0.047 ~ 0.049%Nb+0.21 ~ 0.36%Mo element with the hot-rolled dual-phase steel tensile strength that adopts 500～600 ℃ coiling temperature production; Yield tensile ratio is 0.59 ~ 0.64; But microalloy element content is higher, and production cost is big.
Summary of the invention
The object of the present invention is to provide that a kind of cost is low, the hot-rolled dual-phase steel and the method for manufacture thereof of technology realization easily, stable mechanical property, tensile strength 700MPa low yield strength ratio.
A kind of tensile strength 700MPa hot-rolled dual-phase steel method of manufacture; Its main chemical compositions mass percent is: 0.06% ~ 0.09%C, 1.0% ~ 1.2%Si, 1.10% ~ 1.30%Mn, 0.020% ~ 0.050%Al, 0.4% ~ 0.6%Cr; Surplus is Fe, and tensile strength 700MPa hot-rolled dual-phase steel yield tensile ratio is 0.50 ~ 0.56, and yield tensile ratio is low; Forming property is good, is more suitable for the requirement of automobile structure forming technology
Concrete technical scheme is following:
A kind of 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate according to mass percent, contains 0.06% ~ 0.09%C, 1.0% ~ 1.2%Si, 1.10% ~ 1.30%Mn, 0.020% ~ 0.050%Al, 0.4% ~ 0.6%Cr, and surplus Fe.
Further, its tensile strength is 700MPa ~ 730MPa, and yield tensile ratio is 0.50 ~ 0.57.
Further, its thickness is 2.0mm ~ 6.0mm, and ys is 360MPa ~ 418MPa, unit elongation A
50Be 24.5%～30%.
Further, its n value is 0.22～0.24, and work hardening is 140MPa～174MPa, and baking hardening BH value is 76MPa～89MPa.
The method of manufacture of above-mentioned 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate, adopt following steps:
(1) strand is heated through process furnace;
(2) after heating is come out of the stove, be rolled through the hot continuous rolling unit;
(3) rolling the back adopts laminar flow cooling technology to carry out the segmentation cooling;
(4) batch.
Further, adopt 2250mm hot continuous rolling unit in the step (2), control tapping temperature, finish rolling temperature in, finishing temperature.
Further, in the step (3), control first section quick refrigerative final cooling temperature and middle air cooling time and second section and begin to cool down temperature and final cooling temperature.
Further, slab thickness is 200mm～230mm in the step (1), and strand heated in process furnace 3～4 hours, and tapping temperature is controlled at 1180 ℃～1230 ℃.
Further, in the step (2), on the 2250mm hot continuous mill, carry out breaking down and finish rolling, 1000 ℃～1040 ℃ of control finish rolling temperature ins reach the preceding high-pressure water descaling that adopts of finish rolling before the breaking down with in the breaking down process, adopt stay-warm case between breaking down and the finish rolling.
Further; Adopt the laminar flow type of cooling to carry out segmentation cooling control after the finish rolling; Finish rolling finishes back first section cools off fast, with air cooling after being cooled to 680 ℃～730 ℃ greater than 50 ℃ speed of cooling, behind air cooling 8～12S; Second section begins to cool down 620～650 ℃ of temperature controls, is cooled fast to below 150 ℃.
Compare with present prior art; The hot-rolled dual-phase steel thickness that the present invention adopts chemical ingredients of the present invention, technical process and concrete grammar and step to produce is 2.0mm ~ 6.0mm; Ys is 360MPa ~ 418MPa, and tensile strength is 700MPa ~ 730MPa, unit elongation A
50Be 24.5%～30%, yield tensile ratio is 0.50 ~ 0.57, and the n value is 0.22～0.24, and work hardening is 140MPa～174MPa, and baking hardening BH value is 76MPa～89MPa.
Not only yield tensile ratio is low for the hot-rolled dual-phase steel of the tensile strength 700MPa that employing the present invention produces, and has high work hardening and baking and hardening performance.Automobile factory is used to make automotive wheel, and not only material forming performance and surface quality are good; And automotive wheel has good fatigue property; And realization automotive wheel light-weight design; Can reduce automotive wheel weight 20%, help automobile fuel saving, consumption reduction, have good economic benefit and social benefit.
Description of drawings
Fig. 1 typically organizes photo for tensile strength 700MPa low yield strength ratio hot-rolled dual-phase steel of the present invention
Fig. 2 is the typical stress strain curve of tensile strength 700MPa low yield strength ratio hot-rolled dual-phase steel of the present invention
Wherein Fig. 1 is that tensile strength 700MPa low yield strength ratio hot-rolled dual-phase steel of the present invention is by LEPERA reagent (1%Na
2S
2O
5The aqueous solution+4% picric acid solution) organize photo after the corrosion, brilliant white is organized as martensite in the photo; The stress strain curve that Fig. 2 detects for tensile strength 700MPa low yield strength ratio hot-rolled dual-phase steel mechanical property of the present invention.
Embodiment
Describe the present invention according to accompanying drawing below, it is a kind of preferred embodiment in the numerous embodiments of the present invention.
A kind of hot-rolled dual-phase steel method of manufacture of tensile strength 700MPa low yield strength ratio, its main chemical compositions mass percent is: 0.06% ~ 0.09%C, 1.0% ~ 1.2%Si, 1.10% ~ 1.30%Mn, 0.020% ~ 0.050%Al, 0.4% ~ 0.6%Cr, surplus is Fe.
The present invention adopts above-mentioned chemical ingredients, and the manufacturing process flow process is: hot metal pretreatment → converter smelting → alloy fine setting station → LF → continuous casting → hot continuous rolling → laminar flow cools off → batches.
The present invention adopts above chemical ingredients and technical process production tensile strength 700MPa low yield strength ratio hot-rolled dual-phase steel, specifically carries out according to the following steps:
1) slab thickness is 200mm～230mm, and strand heated in process furnace 3～4 hours, and tapping temperature is controlled at 1180 ℃～1230 ℃.
2) on the 2250mm hot continuous mill, carry out breaking down and finish rolling, 1000 ℃～1040 ℃ of control finish rolling temperature ins.For obtaining favorable surface quality, reach the preceding high-pressure water descaling that adopts of finish rolling before the breaking down with in the breaking down process.For reducing finish rolling inlet strand temperature head, adopt stay-warm case between breaking down and the finish rolling.
3) confirm finish rolling inlet intermediate blank thickness according to the final product thickness specification, the total draft of control finish rolling is more than or equal to 80%.
4) the control finishing temperature is at 820 ℃～870 ℃.
5) adopt the laminar flow type of cooling to carry out segmentation cooling control after the finish rolling; Finish rolling finishes back first section and cools off fast; With air cooling after being cooled to 680 ℃～730 ℃ greater than 50 ℃ speed of cooling; Behind air cooling 8～12S, second section begins to cool down 620～650 ℃ of temperature controls, is cooled fast to below 150 ℃.
6) batch after the cooling, coiling temperature is below 150 ℃.
Chemical ingredients steel shown in the option table 1 is a raw material, and continuous casting steel billet is of a size of 230mm (thick) * 1400mm (wide) * 9000mm (length).Strand is heated, is rolled through 2250mm hot continuous rolling unit then through process furnace; Control tapping temperature, finish rolling temperature in, finishing temperature; Rolling the back adopts laminar flow cooling technology to carry out the segmentation cooling; Control first section quick refrigerative final cooling temperature and middle air cooling time and second section and begin to cool down temperature and final cooling temperature, batch then.Rolling thickness is 2.0mm ~ 6mm.Rolling and process for cooling is seen table 2, and mechanical property is seen table 3.
Table 1 embodiment surveys chemical ingredients (mass percent %, surplus is Fe)
| The composition numbering | C | Si | Mn | P | S | Al | Cr |
| M1 | 0.080 | 1.06 | 1.19 | 0.011 | 0.008 | 0.040 | 0.51 |
| M2 | 0.074 | 1.08 | 1.20 | 0.013 | 0.004 | 0.041 | 0.49 |
| M3 | 0.080 | 1.18 | 1.22 | 0.014 | 0.005 | 0.047 | 0.47 |
Rolling and the process for cooling parameter of table 2 embodiment
Table 3 embodiment mechanical property
Wherein: Rp
0.2-ys; Rm-tensile strength; Rp
0.2/ Rm-yield tensile ratio;
A
50-elongation after fracture; The n-work hardening rate
Table 4 embodiment baking and hardening performance
Explain:
The baking hardening treatment process: after 2% preliminary draft, 170 ℃ are incubated 20 minutes.
Rp
0.2-ys; Rm-tensile strength; Rm
2%Intensity during-preliminary draft 2%;
The BH-baking hardening; Intensity when the BH=baking hardening is handled ys-2% preliminary draft;
△ Rp
0.2Ys behind the=baking hardening-initial ys; Tensile strength-initial tensile strength behind the △ Rm=baking hardening; WH-work hardening; WH=△ Rp
0.2-BH.
Combine accompanying drawing that the present invention has been carried out exemplary description above; Obviously the concrete realization of the present invention does not receive the restriction of aforesaid way; As long as the various improvement of having adopted method design of the present invention and technical scheme to carry out; Or directly apply to other occasion without improvement, all within protection scope of the present invention.
Claims (10)
1. a 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate is characterized in that, according to mass percent, contains 0.06%～0.09%C, 1.0%～1.2%Si, 1.10%～1.30%Mn, 0.020%～0.050%Al, 0. 4%～0.6%Cr, and surplus Fe.
2. 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate as claimed in claim 1 is characterized in that its tensile strength is 700MPa～730MPa, and yield tensile ratio is 0.50～0.57.
3. according to claim 1 or claim 2 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate is characterized in that its thickness is 2.0mm～6.0mm, and ys is 360MPa～418MPa, unit elongation A
50Be 24.5%～30%.
4. like each described 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate among the claim 1-3, it is characterized in that its n value is 0.22～0.24, work hardening is 140MPa～174MPa, and baking hardening BH value is 76MPa～89MPa.
5. like the method for manufacture of the said 700MPa level of claim 1-4 low yield strength ratio hot-rolled dual-phase steel steel plate, it is characterized in that, adopt following steps:
(1) strand is heated through process furnace;
(2) after heating is come out of the stove, be rolled through the hot continuous rolling unit;
(3) rolling the back adopts laminar flow cooling technology to carry out the segmentation cooling;
(4) batch.
6. like the method for manufacture of the said 700MPa level of claim 5 low yield strength ratio hot-rolled dual-phase steel steel plate, it is characterized in that, adopt 2250mm hot continuous rolling unit in the step (2), control tapping temperature, finish rolling temperature in, finishing temperature.
7. like the method for manufacture of claim 5 or 6 said 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plates, it is characterized in that, in the step (3), control first section quick refrigerative final cooling temperature and middle air cooling time and second section and begin to cool down temperature and final cooling temperature.
8. like the method for manufacture of each said 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate among the claim 5-7; It is characterized in that; Slab thickness is 200mm～230mm in the step (1), and strand heated in process furnace 3～4 hours, and tapping temperature is controlled at 1180 ℃～1230 ℃.
9. like the method for manufacture of each said 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate among the claim 5-8; It is characterized in that; In the step (2), on the 2250mm hot continuous mill, carry out breaking down and finish rolling, 1000 ℃～1040 ℃ of control finish rolling temperature ins; Reach the preceding high-pressure water descaling that adopts of finish rolling before the breaking down with in the breaking down process, adopt stay-warm case between breaking down and the finish rolling.
10. like the method for manufacture of each said 700MPa level low yield strength ratio hot-rolled dual-phase steel steel plate among the claim 5-9; It is characterized in that adopt the laminar flow type of cooling to carry out segmentation cooling control after the finish rolling, finish rolling finishes back first section and cools off fast; With air cooling after being cooled to 680 ℃～730 ℃ greater than 50 ℃ speed of cooling; Behind air cooling 8～12S, second section begins to cool down 620～650 ℃ of temperature controls, is cooled fast to below 150 ℃.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103981346A (en) * | 2013-02-07 | 2014-08-13 | 中国钢铁股份有限公司 | Method for manufacturing low-yield-ratio steel |
| CN110369507A (en) * | 2019-06-18 | 2019-10-25 | 包头钢铁（集团）有限责任公司 | A method of efficiently removing high Si steel hot-rolled sheet belt surface red oxide |
| WO2020103927A1 (en) | 2018-11-23 | 2020-05-28 | 宝山钢铁股份有限公司 | High-yield-ratio cold-rolled dual-phase steel and manufacturing method therefor |
| CN112246868A (en) * | 2020-08-20 | 2021-01-22 | 唐山钢铁集团有限责任公司 | Production method of substrate for cold rolling of 700 Mpa-level high-strength checkered plate |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5629626A (en) * | 1979-08-20 | 1981-03-25 | Kobe Steel Ltd | Manufacture of hot-rolled steel plate |
| CN1970813A (en) * | 2006-12-18 | 2007-05-30 | 马鞍山钢铁股份有限公司 | Process for production of hot-rolled dual phase steel by continuous casting and continuous rolling of slab billet |
-
2012
- 2012-06-19 CN CN201210203060.4A patent/CN102766812B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5629626A (en) * | 1979-08-20 | 1981-03-25 | Kobe Steel Ltd | Manufacture of hot-rolled steel plate |
| CN1970813A (en) * | 2006-12-18 | 2007-05-30 | 马鞍山钢铁股份有限公司 | Process for production of hot-rolled dual phase steel by continuous casting and continuous rolling of slab billet |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103981346A (en) * | 2013-02-07 | 2014-08-13 | 中国钢铁股份有限公司 | Method for manufacturing low-yield-ratio steel |
| CN103981346B (en) * | 2013-02-07 | 2016-06-08 | 中国钢铁股份有限公司 | Method for manufacturing low-yield-ratio steel |
| WO2020103927A1 (en) | 2018-11-23 | 2020-05-28 | 宝山钢铁股份有限公司 | High-yield-ratio cold-rolled dual-phase steel and manufacturing method therefor |
| CN110369507A (en) * | 2019-06-18 | 2019-10-25 | 包头钢铁（集团）有限责任公司 | A method of efficiently removing high Si steel hot-rolled sheet belt surface red oxide |
| CN112246868A (en) * | 2020-08-20 | 2021-01-22 | 唐山钢铁集团有限责任公司 | Production method of substrate for cold rolling of 700 Mpa-level high-strength checkered plate |
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