CN102758131B - Production method of 600MPa grade cold rolling dual-phase steel - Google Patents
Production method of 600MPa grade cold rolling dual-phase steel Download PDFInfo
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Abstract
The invention relates to a production method of 600MPa grade cold rolling dual-phase steel and belongs to the technical field of metallurgical sheet material production. The technical scheme of the production method comprises working procedures of smelting in a converter, LF (ladle furnace) refining, continuous casting, hot rolling, cold rolling and continuous annealing. The final chemical components according to mass percent are as follows: 0.06-0.09% of C, 0.4-0.6% of Si, 1.65-1.75% of Mn, less than or equal to 0.01% of P, less than or equal to 0.015% of S, 0.025-0.06% of Als, less than or equal to 0.004% of N, and the balance of Fe. Molten iron requirements in the procedure of smelting in the converter are as follows: S is less than or equal to 0.040%, desulfurization target S is less than or equal to 0.010%, added steel scrap is 4-8% of total mass of the molten iron, and hot metal ratio is more than or equal to 85%. In the production method, no alloy element is added; composition of C-Si-Mn series dual-phase steel is improved; Si content is decreased; Al content is increased; and cold rolling dual-phase steel with low yield ratio and high elongation coefficient is produced by improving smelting, hot rolling, cold rolling and continuous annealing processes; the cost is low; the production procedures are continuous; and the product quality is stable. The mechanical property of the finished product is as follows: yield strength is about 360-430MPa, tensile strength is more than or equal to 600MPa, and elongation coefficient is more than or equal to 25%.
Description
Technical field
The production method that the present invention relates to a kind of 600MPa level cold-rolled biphase steel, belongs to metallurgical plate production technical field.
Background technology
At present, the composition system of producing 600MPa level cold-rolled biphase steel is mainly C-Si-Mn series, C-Si-Mn-Cr series, C-Si-Mn-Cr-Mo, C-Si-Mn-Nb and C-Al-Mn series etc.Produce when the difficult point of cold-rolled biphase steel is to anneal and need to control higher cooling rate, and control lower final cooling temperature, make to exist in cold rolling finished product ferrite, martensite two-phase.The Martensite Volume Fraction deficiency forming when cooling rate slowly or final cooling temperature is higher, even can not form martensite, causes finished product low cross-intensity, affects quality product.But high speed of cooling and low final cooling temperature are higher to equipment requirements.Taking the C-Si-Mn series dual phase steel of common constituent as example, its martensitic transformation temperature is generally 250 DEG C of left and right, and higher to equipment requirements, industrialized mass production exists certain difficulty.
In order to reduce production difficulty, people add the alloying element that strengthens stabilization of austenite in steel, as Cr, Mo etc., for example: name is called the Chinese patent application of " tensile strength 600 MPa grade aluminum system cold-rolled dual phase steel ", number of patent application 200910272186.5, has added Mo exactly; After adding these alloying elements, be conducive to improve martensitic transformation temperature, improve final cooling temperature, reduce cooling rate, thereby reduced the requirement to equipment.But the alloy such as Cr, Mo price is higher, and production cost is higher, cause finished product price higher, be unfavorable for that the marketization of dual phase steel is promoted.Background technology, in order to produce 600MPa level dual phase steel low cost and the favourable production in the situation that, adds Nb in C-Si-Mn composition system, or increases Al content, with Al for Si.Nb has certain stable effect that strengthens stabilization of austenite and crystal grain thinning, but DeGrain.Al has remarkable effect to improving stabilization of austenite, but in background technology, mentions Al content higher (approximately 1.0%) at present.In the time that Al content is higher, smelt castability and significantly reduce, be unfavorable for continuous production.
Summary of the invention
The object of the invention is to provide a kind of production method of 600MPa level cold-rolled biphase steel, on the composition basis of C-Si-Mn dual phase steel, reduce Si content, increase appropriate Al content, improve stabilization of austenite by Si, Al, reduce production difficulty, do not affect again smelting castability, cost is low, continuous production is better, and constant product quality solves the problems referred to above that background technology exists.
Technical solution of the present invention is:
A kind of production method of 600MPa level cold-rolled biphase steel, comprise converter smelting, LF refining, continuous casting, hot rolling, cold-rolling continuous annealing operation, the mass percent of final chemical composition is: C:0.06-0.09%, Si:0.4-0.6, Mn:1.65-1.75, P≤0.01%, S≤0.015%, Als:0.025-0.06%, N≤0.004%, remains as Fe; The molten iron of converter smelting operation requires: S≤0.040%, and desulfurization target S≤0.010%, steel scrap adds the 4-8% that accounts for molten iron total mass, hot metal ratio >=85%.
Described LF refining procedure, basicity is pressed 4.0-4.5 and is controlled, terminal target C≤0.055%, P < 0.007%, S≤0.02%.
LF ladle bottom blowing Ar opens to flow 80Nm3/h, and the treatment time is controlled in 40min, under the prerequisite of having buried arc, ensures omnidistance malleation; Refining out-station temperature 1558-1565 DEG C.
Described hot-rolled process, requires low-temperature heat, high-temperature final rolling, and high temperature coiling: a, hot rolling Heating temperature are 1180-1220 DEG C; B, finish rolling start rolling temperature are 1020-1080 DEG C; C, finishing temperature are 820-880 DEG C; D, coiling temperature are 620-680 DEG C, and coiling temperature and trimmed size match; In e, course of hot rolling, roughing stay-warm case normally drops into, needless to say warm after roughing finishes.
Described cold-rolling continuous annealing operation, requires soaking temperature, to produce the necessary two-phase structure of dual phase steel; Control rapid cooling cooling rate, the austenite phase transformation product forming while ensureing soaking is martensite; Control rapid cooling final cooling temperature, move back soaking temperature as 800-840 DEG C to ensure that the condensate depression of martensitic transformation: a, continuous annealing process connect; B, slow cooling final cooling temperature are 650-700 DEG C; C, rapid cooling end temp are 290-330 DEG C; D, completion of prescription temperature are 200-300 DEG C; E, belt speed are controlled between 70-270m/min, and belt speed control and product thickness match, and while distributing belt speed, cooling rate is higher than 25 DEG C/s.Smooth elongation control is between 0.5-1.0%, and smooth unit elongation and thickness match.
Described LF refining procedure, bottom blowing adopts omnidistance Argon pattern, is undertaken by low nitrogen, low-phosphorous, low-sulfur operator scheme, and converting process adopts the large quantity of slag, full range slag.Terminal target C≤0.055%, P < 0.007%, S≤0.02%.In order to reduce blow off N content, add mass ratio 0.4-0.6% lime.LF refining out-station temperature 1558-1565 DEG C, the first stove, non-turnover bag out-station temperature can improve 5-10 DEG C.
Positively effect of the present invention: the present invention does not add any alloying element, the composition of having improved C-Si-Mn series dual phase steel, has reduced Si and has contained, and has increased Al content, by improving steel-making, hot rolling technology, cold-rolling continuous annealing technique, produce the cold-rolled biphase steel that yield tensile ratio is low, unit elongation is high; Cost is low, and continuous production is better, constant product quality.Finished product mechanical performance index of the present invention: the about 360-430MPa of yield strength, tensile strength approximately >=600MPa, unit elongation >=25%.
Embodiment
The invention will be further described by the following examples.
In an embodiment, a kind of production method of 600MPa level cold-rolled biphase steel, comprise converter smelting, LF refining, continuous casting, hot rolling, cold-rolling continuous annealing operation, the mass percent of final chemical composition is: C:0.06-0.09%, Si:0.4-0.6, Mn:1.65-1.75, P≤0.01%, S≤0.015%, Als:0.025-0.06%, N≤0.004%, remains as Fe; The molten iron of converter smelting operation requires: S≤0.040%, and desulfurization target S≤0.010%, steel scrap adds the 4-8% that accounts for molten iron total mass, hot metal ratio >=85%.
1, converter smelting, LF refining, continuous casting working procedure
Final steel chemical composition is as shown in table 1.
Table 1 chemical composition
(chemical composition: wt%)
Describe with embodiment 1: molten iron condition: molten iron S:0.025%, adding amount of scrap steel: 5.3%, hot metal ratio 87%, 273 tons of target taps.Bottom-blowing of converter adopts omnidistance Argon pattern; Basicity is controlled by 4.3, terminal target C:0.025%, P:0.006%, S:0.004%.Add the lime of mass ratio 0.52%.LF ladle bottom blowing Ar, the treatment time is controlled at 30min, omnidistance positive pressure operation, 1563 DEG C of refining out-station temperatures.
2, hot-rolled process
1200 ± 10 DEG C of Heating temperatures, heat-up time 40min, finish rolling start rolling temperature is 1050 ± 10 DEG C, 850 ± 20 DEG C of finishing temperatures, 650 ± 20 DEG C of concrete technologies of coiling temperature are in table 2.Embodiment mono-strand rolling three volumes, the corresponding heat (batch) number of smelting of hot rolling reel number, reel number is numbered 1-10.Concrete technology parameter is in table 2.
Table 2 hot-rolled process parameter
This hot rolling technology coiling temperature is higher, is conducive to reduce hot-rolled finished product intensity, reduces cold rolling mill load, is conducive to control cold rolled sheet shape, improves cold-rolled products quality.
3, cold-rolling continuous annealing operation
Cold rolling trimmed size is 1200 × 1.5mm, and cold rolling draft control is 62.5%, the corresponding hot rolling reel number of cold rolling reel number, and cold rolling reel number is numbered 1-10, and annealing process is in table 3.
Table 3 even moves back parameter
Smooth unit elongation unification is according to 1.1% setting, and this time trial-production cooling rate is 35 DEG C/s.
820 DEG C of soaking are conducive to obtain the austenite of volume fraction approximately 25% and the ferrite of volume fraction approximately 75% in even moving back process.Behind slow cooling section, having part austenitic transformation is ferrite, the austenite volume fraction approximately 5% of transformation, and now the ratio of austenite and ferritic volume fraction is about 2:8.After rapid cooling, this remainder austenitic transformation is martensite, forms the necessary martensite of dual phase steel and adds ferrite two-phase structure, Martensite Volume Fraction approximately 20% in finished product.By compound interpolation Si, Al alloy, the martensite transformation temperature of the cold-reduced sheet of this patent composition used is 340 DEG C, the martensite transformation temperature that is the C-Si-Mn dual phase steel of 250 DEG C than traditional martensite transformation temperature has improved approximately 90 DEG C, reach reduction production difficulty, ensured the object that continuous batch is produced.In actual production process, rapid cooling temperature is decided to be to 300 DEG C, for martensitic transformation provides enough condensate depression, in ensureing martensitic transformation, reaches the object that makes martenaging martempering, ensured the intensity of finished product, improved again the toughness of steel.
Product mechanical property is in table 4.
Table 4 mechanical property
In table 4, mechanical property meets the requirement of 600MPa level cold-rolled biphase steel completely.
Claims (3)
1. the production method of a 600MPa level cold-rolled biphase steel, it is characterized in that comprising converter smelting, LF refining, continuous casting, hot rolling, cold-rolling continuous annealing operation, the mass percent of final chemical composition is: C:0.06-0.09%, Si:0.4-0.6%, Mn:1.65-1.75%, P≤0.01%, S≤0.015%, Als:0.025-0.06%, N≤0.004%, remains as Fe; The molten iron of converter smelting operation requires: S≤0.040%, and desulfurization target S≤0.010%, steel scrap adds the 4-8% that accounts for molten iron total mass, hot metal ratio >=85%;
Described LF refining procedure, basicity is pressed 4.0-4.5 and is controlled, terminal target C≤0.055%, P < 0.007%, S≤0.02%;
LF ladle bottom blowing Ar opens to flow 80Nm
3/ h, the treatment time is controlled in 40min, under the prerequisite of having buried arc, ensures omnidistance malleation; Refining out-station temperature 1558-1565 DEG C;
Described hot-rolled process, requires low-temperature heat, high-temperature final rolling, and high temperature coiling: a, hot rolling Heating temperature are 1180-1220 DEG C; B, finish rolling start rolling temperature are 1020-1080 DEG C; C, finishing temperature are 820-880 DEG C; D, coiling temperature are 620-680 DEG C, and coiling temperature and trimmed size match; In e, course of hot rolling, roughing stay-warm case normally drops into, needless to say warm after roughing finishes.
2. a kind of production method of 600MPa level cold-rolled biphase steel according to claim 1, is characterized in that described cold-rolling continuous annealing operation, requires soaking temperature, to produce the necessary two-phase structure of dual phase steel; Control rapid cooling cooling rate, the austenite phase transformation product forming while ensureing soaking is martensite; Control rapid cooling final cooling temperature, move back soaking temperature as 800-840 DEG C to ensure that the condensate depression of martensitic transformation: a, continuous annealing process connect; B, slow cooling final cooling temperature are 650-700 DEG C; C, rapid cooling end temp are 250-350 DEG C; D, completion of prescription temperature are 200-300 DEG C; E, belt speed are controlled between 70-270m/min, and belt speed control and product thickness match, and while distributing belt speed, cooling rate is higher than 25 DEG C/s; Smooth elongation control is between 0.5-1.0%, and smooth unit elongation and thickness match.
3. according to the production method of a kind of 600MPa level cold-rolled biphase steel described in claim 1 or 2, it is characterized in that described LF refining procedure, bottom blowing adopts omnidistance Argon pattern, undertaken by low nitrogen, low-phosphorous, low-sulfur operator scheme, converting process adopts the large quantity of slag, and full range slag adds mass ratio 0.4% lime; LF refining out-station temperature 1558-1565 DEG C, the first stove, non-turnover bag out-station temperature improve 5-10 DEG C.
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| CN103088255B (en) * | 2013-01-02 | 2014-12-03 | 河北钢铁股份有限公司邯郸分公司 | Manufacturing process of automobile low-alloy high-strength steel cold-rolled sheet with high product of strength and elongation |
| CN103938101B (en) * | 2014-04-10 | 2016-08-31 | 马钢(集团)控股有限公司 | A kind of steel plate and preparation method thereof |
| CN104313460A (en) * | 2014-10-13 | 2015-01-28 | 河北钢铁股份有限公司邯郸分公司 | 500MPa-grade cold rolling dual-phase steel and production method thereof |
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| CN106755867B (en) * | 2016-12-01 | 2019-01-18 | 首钢集团有限公司 | A kind of hot dip galvanized dual phase steel surface treatment method |
| CN107012392B (en) * | 2017-05-15 | 2019-03-12 | 河钢股份有限公司邯郸分公司 | A kind of 600MPa grade high-strength low-alloy cold-strip steel and its production method |
| CN108411202A (en) * | 2018-04-03 | 2018-08-17 | 本钢板材股份有限公司 | A kind of think gauge cold-rolled biphase steel and preparation method thereof |
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| CN108517468B (en) * | 2018-05-24 | 2020-09-22 | 山东钢铁集团日照有限公司 | One-steel multi-stage economical cold-rolled dual-phase steel and production method thereof |
| CN109136739B (en) * | 2018-06-29 | 2020-08-04 | 唐山钢铁集团有限责任公司 | Control method for coatable performance surface quality of dual-phase steel cold-rolled high-strength automobile plate |
| CN111961962A (en) * | 2020-07-24 | 2020-11-20 | 江苏沙钢集团有限公司 | Rolling method of normalized structural steel |
| CN114150216A (en) * | 2021-11-04 | 2022-03-08 | 本钢板材股份有限公司 | Low-cost 600 MPa-grade cold-rolled DP steel and production method thereof |
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| CN102212745A (en) * | 2011-06-03 | 2011-10-12 | 首钢总公司 | High-plasticity 780MPa-level cold rolled dual-phase steel and preparation method thereof |
Non-Patent Citations (2)
| Title |
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| C-Si-Mn冷轧双相钢的应变硬化特性;邝霜等;《材料工程》;20091231(第2期);第11-14页和第18页 * |
| 邝霜等.C-Si-Mn冷轧双相钢的应变硬化特性.《材料工程》.2009,(第2期),第11-14页和第18页. |
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