CN105132817A - 1200MPa-grade cold-rolled annealed dual-phase steel and production method thereof - Google Patents
1200MPa-grade cold-rolled annealed dual-phase steel and production method thereof Download PDFInfo
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- CN105132817A CN105132817A CN201510637974.5A CN201510637974A CN105132817A CN 105132817 A CN105132817 A CN 105132817A CN 201510637974 A CN201510637974 A CN 201510637974A CN 105132817 A CN105132817 A CN 105132817A
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Abstract
The invention discloses1200MPa-grade cold-rolled annealed dual-phase steel and a production method thereof. The production method of the 1200MPa-grade cold-rolled annealed dual-phase steel comprises the steps of hot rolling, cold rolling and annealing, and flattening. A continuous casted billet prepared from, by mass, 0.14%-0.20% of C, 1.5%-2.0% of Mn, 0%-0.005% of S, 0%-0.010% of P, 0.2%-0.6% of Si, 0.015%-0.030% of Nb, 0.010%-0.030% of Ti, 0.030% or more of Als, 0.30%-0.70% of Cr, 0%-0.000050% of N and the balance Fe and inevitable impurities is subjected to hot rolling. The tensile strength of the dual-phase steel is over 1200 MPa, the percentage elongation after fracture of the dual-phase steel is over 6%, and the dual-phase steel has the continuous yielding property and the good bake hardening performance; the dual-phase steel can be used for manufacturing mechanical anti-collision parts and reinforcing parts and particularly can be used for manufacturing anti-collision parts and reinforcing parts of automobiles and doorsill footboards of the automobiles.
Description
Technical field
The present invention relates to a kind of cold rolling high strength steel plate, the cold rolled annealed dual phase steel of especially a kind of automobile 1200MPa level and production method thereof.
Background technology
In order to satisfied reduction body of a motor car deadweight reaches the object reducing energy consumption, ensure that the safety performance of vehicle body can not reduce simultaneously, in Automobile Body Design, adopt high-strength steel more and more, especially advanced high-strength steel, wherein dual phase steel is used in automobile component are produced gradually owing to having the excellent performance such as low yield strength, high-tensile and high initial manufacture hardening rate.
At present, successful knowhow about the cold rolled annealed dual phase steel of 1200MPa rank is little, mainly concentrate on laboratory study, if publication number is disclose a kind of tensile strength 1200MPa level cold-rolled biphase steel plate and preparation method in CN102021483A, it adopts grain refining intensificatiom and controls martensite content and carrys out control intensity; But its thickness is only 1.0mm, and move back line production dual phase steel for connecting, along with the increase of matrix thickness, the difficulty of production is increasing.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of cold rolled annealed dual phase steel of 1200MPa level compared with think gauge; Present invention also offers the production method of the cold rolled annealed dual phase steel of a kind of technique simple 1200MPa level.
For solving the problems of the technologies described above, the mass percentage of chemical composition of the present invention is: C0.14 ~ 0.20%, Mn1.5 ~ 2.0%, S≤0.005%, P≤0.010%, Si0.2 ~ 0.6%, Nb0.015 ~ 0.030%, Ti0.010 ~ 0.030%, Als >=0.030%, Cr0.30 ~ 0.70%, N≤50ppm, all the other are Fe and inevitable impurity.
The thickness specification of dual phase steel of the present invention is 1.0 ~ 2.5mm.
Mentality of designing of the present invention is: C: carbon is solution strengthening element, and be the guarantee that material obtains high strength, when carbon content is too low, when identical critical zone (ferrite and austenite) is heated, austenite content is low, is unfavorable for obtaining high intensity; But carbon content is too high, be unfavorable for the welding property of material; Therefore the design of carbon is more low better on the basis meeting intensity.Mn: manganese is the element strongly improving austenite hardening capacity, the austenite containing appropriate Mn can obtain the tissue of expectation by different rapid cooling final temperatures, thus obtains the product of different performance.Si: be solution strengthening element, can improve the strength of materials on the one hand; On the other hand, carbon can be accelerated to austenite segregation, purification ferrite, thus improve end properties.Nb: be Carbonitride Precipitation element, can crystal grain thinning and separate out carbonitride, improves material matrix intensity.Ti: be Carbonitride Precipitation element, for improving material matrix intensity.Cr: play strengthening effect on the one hand; Be mainly used for temperature area bainite transformation in postponement on the other hand, thus ensure to obtain martensitic stucture under low speed of cooling.
The inventive method comprises hot rolling, cold rolled annealed and smooth operation, adopts the continuously cast bloom of above-mentioned mass percent chemical composition to carry out hot rolling.
Hot-rolled process described in the inventive method: the soaking temperature of continuously cast bloom 1250 ~ 1280 DEG C, soaking time is 25 ~ 35min; Come out of the stove rolling, finishing temperature is 860 ~ 880 DEG C, and adopt leading portion cooling mode, coiling temperature is 550 ~ 680 DEG C.
Cold rolled annealed operation described in the inventive method: cold rolling draft is 40 ~ 60%; The soaking temperature of annealing process is 760 ~ 820 DEG C, and it is 630 ~ 760 DEG C that rapid cooling starts temperature, and overaging temperature is 250 ~ 300 DEG C, and production technique speed is 60 ~ 160m/min.
Smooth operation described in the inventive method: smooth draft 0.2 ~ 0.5%.
The beneficial effect adopting technique scheme to produce is: tensile strength of the present invention is at more than 1200MPa, and elongation after fracture, more than 6%, has continuous yield characteristics and good baking and hardening performance; Can be used for the purposes in the anti-striker of processing machinery and stiffener, be particularly useful for the doorsill pedal preparing the anti-striker of automobile, stiffener and automobile.
The hot-rolled process of the inventive method, is heated to assigned temperature by continuously cast bloom, realizes the solid solution of Nb element, non-uniform components; And alleviate banded structure, for hot-rolled process provides suitable strand; Hot rolling is mainly ferrite and pearlite hot rolled strip to obtain tissue.In cold rolled annealed operation, cold-rolled process except thinning to belt steel thickness, mainly for annealing process provide have mass storage can chill plate, for annealing recrystallization provides motivating force; Annealing process, by the adjustment of soaking temperature, can change ferrite and austenitic relative content under high temperature, and realize C and Mn element to austenite segregation through diffusion, complete the Recovery and recrystallization of chill volume simultaneously; The setting that rapid cooling starts temperature can regulate and control to be cooled to the ferritic amount of precipitation of extension this temperature course from soaking temperature, regulation and control austenite and ferrite content further on the one hand, and plays the ferritic effect of purification; Regulate rapid cooling cooling temperature on the other hand, to obtain the cooling rate higher than critical cooling velocity, guarantee that residual austenite changes martensite into completely; Aborning, rapid cooling terminates namely to enter overaging section, so, overaging temperature equals rapid cooling end temp, overaging temperature determines the speed of cooling of rapid cooling section on the one hand, on the other hand, the overaging at specific overaging temperature can eliminate the unrelieved stress formed in martensitic transformation process, improves finished product plasticity.
Embodiment
Below in conjunction with specific embodiment, the present invention is further detailed explanation, and wherein, the chemical composition content of each embodiment steel grade is in table 1.
Table 1: the chemical composition (wt%) of steel grade
In table 1, the surplus of chemical composition is Fe and inevitable impurity.
The production method of the cold rolled annealed dual phase steel of embodiment 1: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 130min, the soaking temperature of strand 1280 DEG C, soaking time is 28min; Come out of the stove rolling, finishing temperature is 875 DEG C, and adopt leading portion cooling mode, coiling temperature is 550 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 60%, the soaking temperature of annealing steps is 780 DEG C, and it is 630 DEG C that rapid cooling starts temperature, and overaging temperature is 280 DEG C, production technique speed is 160m/min, and described production technique speed refers to the travelling speed of band steel in continuous annealing furnace.
(3) smooth operation: draft 0.5%, can obtain the dual phase steel that thickness is 1.0mm after smooth.
The production method of the cold rolled annealed dual phase steel of embodiment 2: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 120min, the soaking temperature of strand 1280 DEG C, soaking time is 30min; Come out of the stove rolling, finishing temperature is 860 DEG C, and adopt leading portion cooling mode, coiling temperature is 680 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 55.0%, the soaking temperature of annealing steps is 820 DEG C, and it is 760 DEG C that rapid cooling starts temperature, and overaging temperature is 300 DEG C, and production technique speed is 125m/min.
(3) smooth operation: draft 0.4%, can obtain the dual phase steel that thickness is 1.3mm after smooth.
The production method of the cold rolled annealed dual phase steel of embodiment 3: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 128min, the soaking temperature of strand 1275 DEG C, soaking time is 32min; Come out of the stove rolling, finishing temperature is 870 DEG C, and adopt leading portion cooling mode, coiling temperature is 620 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 50%, the soaking temperature of annealing steps is 800 DEG C, and it is 700 DEG C that rapid cooling starts temperature, and overaging temperature is 260 DEG C, and production technique speed is 105m/min.
(3) smooth operation: draft 0.4%, can obtain the dual phase steel that thickness is 1.5mm after smooth.
The production method of the cold rolled annealed dual phase steel of embodiment 4: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 125min, the soaking temperature of strand 1250 DEG C, soaking time is 25min; Come out of the stove rolling, finishing temperature is 865 DEG C, and adopt leading portion cooling mode, coiling temperature is 630 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 48.5%, the soaking temperature of annealing steps is 790 DEG C, and it is 730 DEG C that rapid cooling starts temperature, and overaging temperature is 250 DEG C, and production technique speed is 90m/min.
(3) smooth operation: draft 0.3%, can obtain the dual phase steel that thickness is 1.8mm after smooth.
The production method of the cold rolled annealed dual phase steel of embodiment 5: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 128min, the soaking temperature of strand 1270 DEG C, soaking time is 27min; Come out of the stove rolling, finishing temperature is 880 DEG C, and adopt leading portion cooling mode, coiling temperature is 610 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 50.0%, the soaking temperature of annealing steps is 760 DEG C, and it is 650 DEG C that rapid cooling starts temperature, and overaging temperature is 290 DEG C, and production technique speed is 80m/min.
(3) smooth operation: draft 0.5%, can obtain the dual phase steel that thickness is 2.0mm after smooth.
The production method of the cold rolled annealed dual phase steel of embodiment 6: this 1200MPa level adopts following concrete technology.
(1) hot-rolled process: time inside furnace 138min, the soaking temperature of strand 1265 DEG C, soaking time is 35min; Come out of the stove rolling, finishing temperature is 860 DEG C, and adopt leading portion cooling mode, coiling temperature is 650 DEG C.
(2) cold rolled annealed operation: cold rolling draft is 40.0%, the soaking temperature of annealing steps is 780 DEG C, and it is 680 DEG C that rapid cooling starts temperature, and overaging temperature is 270 DEG C, and production technique speed is 60m/min.
(3) smooth operation: draft 0.2%, can obtain the dual phase steel that thickness is 2.5mm after smooth.
The mechanical property of the various embodiments described above gained dual phase steel product is in table 2, and wherein, during tensile property test, tension specimen is parallel to rolling direction, and the gauge length of tension specimen is 80mm.
Table 2: the mechanical property of each embodiment dual phase steel product
Claims (6)
1. the cold rolled annealed dual phase steel of 1200MPa level, is characterized in that, the mass percentage of its chemical composition is: C0.14 ~ 0.20%, Mn1.5 ~ 2.0%, S≤0.005%, P≤0.010%, Si0.2 ~ 0.6%, Nb0.015 ~ 0.030%, Ti0.010 ~ 0.030%, Als >=0.030%, Cr0.30 ~ 0.70%, N≤50ppm, all the other are Fe and inevitable impurity.
2. the cold rolled annealed dual phase steel of 1200MPa level according to claim 1, is characterized in that: the thickness specification of described dual phase steel is 1.0 ~ 2.5mm.
3. a production method for the cold rolled annealed dual phase steel of 1200MPa level, comprises hot rolling, cold rolled annealed and smooth operation, it is characterized in that, the continuously cast bloom of following mass percent chemical composition is adopted to carry out hot rolling: C0.14 ~ 0.20%, Mn1.5 ~ 2.0%, S≤0.005%, P≤0.010%, Si0.2 ~ 0.6%, Nb0.015 ~ 0.030%, Ti0.010 ~ 0.030%, Als >=0.030%, Cr0.30 ~ 0.70%, N≤50ppm, all the other are Fe and inevitable impurity.
4. the production method of the cold rolled annealed dual phase steel of 1200MPa level according to claim 3, it is characterized in that, described hot-rolled process: the soaking temperature of continuously cast bloom 1250 ~ 1280 DEG C, soaking time is 25 ~ 35min; Come out of the stove rolling, finishing temperature is 860 ~ 880 DEG C, and adopt leading portion cooling mode, coiling temperature is 550 ~ 680 DEG C.
5. the production method of the cold rolled annealed dual phase steel of 1200MPa level according to claim 3, is characterized in that, described cold rolled annealed operation: cold rolling draft is 40 ~ 60%; The soaking temperature of annealing process is 760 ~ 820 DEG C, and it is 630 ~ 760 DEG C that rapid cooling starts temperature, and overaging temperature is 250 ~ 300 DEG C, and production technique speed is 60 ~ 160m/min.
6. the production method of the cold rolled annealed dual phase steel of 1200MPa level according to claim 3,4 or 5, is characterized in that, described smooth operation: smooth draft 0.2 ~ 0.5%.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106734246A (en) * | 2016-11-21 | 2017-05-31 | 首钢京唐钢铁联合有限责任公司 | Method for reducing chromatic aberration of cold-rolled dual-phase steel |
| CN107142426A (en) * | 2017-06-21 | 2017-09-08 | 唐山钢铁集团有限责任公司 | A kind of superhigh intensity annealed sheet steel and its manufacture method |
| CN108193139A (en) * | 2018-02-23 | 2018-06-22 | 唐山钢铁集团有限责任公司 | 1180MPa grades of automobile cold-rolled high-strength dual phase steels and its production method |
| CN108642379A (en) * | 2018-05-15 | 2018-10-12 | 首钢集团有限公司 | A kind of tensile strength 1200MPa grades of cold-rolled biphase steels and preparation method thereof |
| CN109280857A (en) * | 2018-09-25 | 2019-01-29 | 邯郸钢铁集团有限责任公司 | A kind of 1200MPa grades of ultrafast cold cold-rolled biphase steel plate and preparation method thereof |
| CN109628846A (en) * | 2018-12-20 | 2019-04-16 | 唐山钢铁集团有限责任公司 | 1300MPa grades of automobile super high tensile cold-rolled steel plates and its production method |
| CN113308649A (en) * | 2021-05-14 | 2021-08-27 | 唐山钢铁集团有限责任公司 | Low-yield-ratio 1000 MPa-grade cold-rolled dual-phase strip steel and production method thereof |
| CN113528932A (en) * | 2021-05-31 | 2021-10-22 | 唐山钢铁集团高强汽车板有限公司 | Martensite steel plate and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101768695A (en) * | 2010-01-21 | 2010-07-07 | 北京科技大学 | Ti microalloyed ultra-fine grained cold rolling dual-phase steel of 1,000MPa level and preparation method thereof |
| CN102586688A (en) * | 2011-01-10 | 2012-07-18 | 宝山钢铁股份有限公司 | Double-phase steel plate and manufacturing method thereof |
| CN102828119A (en) * | 2011-06-14 | 2012-12-19 | 鞍钢股份有限公司 | High-bending 980 MPa-grade cold-rolled dual-phase steel and preparation process thereof |
-
2015
- 2015-09-30 CN CN201510637974.5A patent/CN105132817A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101768695A (en) * | 2010-01-21 | 2010-07-07 | 北京科技大学 | Ti microalloyed ultra-fine grained cold rolling dual-phase steel of 1,000MPa level and preparation method thereof |
| CN102586688A (en) * | 2011-01-10 | 2012-07-18 | 宝山钢铁股份有限公司 | Double-phase steel plate and manufacturing method thereof |
| CN102828119A (en) * | 2011-06-14 | 2012-12-19 | 鞍钢股份有限公司 | High-bending 980 MPa-grade cold-rolled dual-phase steel and preparation process thereof |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106734246A (en) * | 2016-11-21 | 2017-05-31 | 首钢京唐钢铁联合有限责任公司 | Method for reducing chromatic aberration of cold-rolled dual-phase steel |
| CN106734246B (en) * | 2016-11-21 | 2019-03-05 | 首钢京唐钢铁联合有限责任公司 | Method for reducing chromatic aberration of cold-rolled dual-phase steel |
| CN107142426B (en) * | 2017-06-21 | 2019-05-24 | 唐山钢铁集团有限责任公司 | A kind of superhigh intensity annealed sheet steel and its manufacturing method |
| CN107142426A (en) * | 2017-06-21 | 2017-09-08 | 唐山钢铁集团有限责任公司 | A kind of superhigh intensity annealed sheet steel and its manufacture method |
| CN108193139A (en) * | 2018-02-23 | 2018-06-22 | 唐山钢铁集团有限责任公司 | 1180MPa grades of automobile cold-rolled high-strength dual phase steels and its production method |
| CN108193139B (en) * | 2018-02-23 | 2019-09-10 | 唐山钢铁集团有限责任公司 | 1180MPa grades of automobile cold-rolled high-strength dual phase steels and its production method |
| CN108642379B (en) * | 2018-05-15 | 2020-07-24 | 首钢集团有限公司 | Cold-rolled dual-phase steel with tensile strength of 1200MPa and preparation method thereof |
| CN108642379A (en) * | 2018-05-15 | 2018-10-12 | 首钢集团有限公司 | A kind of tensile strength 1200MPa grades of cold-rolled biphase steels and preparation method thereof |
| CN109280857A (en) * | 2018-09-25 | 2019-01-29 | 邯郸钢铁集团有限责任公司 | A kind of 1200MPa grades of ultrafast cold cold-rolled biphase steel plate and preparation method thereof |
| CN109280857B (en) * | 2018-09-25 | 2021-03-05 | 邯郸钢铁集团有限责任公司 | 1200 MPa-grade ultrafast cold-rolled dual-phase steel plate and preparation method thereof |
| CN109628846A (en) * | 2018-12-20 | 2019-04-16 | 唐山钢铁集团有限责任公司 | 1300MPa grades of automobile super high tensile cold-rolled steel plates and its production method |
| CN109628846B (en) * | 2018-12-20 | 2020-08-04 | 唐山钢铁集团有限责任公司 | 1300 MPa-grade ultrahigh-strength cold-rolled steel plate for automobiles and production method thereof |
| CN113308649A (en) * | 2021-05-14 | 2021-08-27 | 唐山钢铁集团有限责任公司 | Low-yield-ratio 1000 MPa-grade cold-rolled dual-phase strip steel and production method thereof |
| CN113528932A (en) * | 2021-05-31 | 2021-10-22 | 唐山钢铁集团高强汽车板有限公司 | Martensite steel plate and preparation method thereof |
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