CN102732791A - Production method of cold-rolled dual phase steel with tensile strength of 450MPa - Google Patents
Production method of cold-rolled dual phase steel with tensile strength of 450MPa Download PDFInfo
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- CN102732791A CN102732791A CN2012101854607A CN201210185460A CN102732791A CN 102732791 A CN102732791 A CN 102732791A CN 2012101854607 A CN2012101854607 A CN 2012101854607A CN 201210185460 A CN201210185460 A CN 201210185460A CN 102732791 A CN102732791 A CN 102732791A
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Abstract
The invention relates to a production method of cold-rolled dual phase steel with the tensile strength of 450MPa, and belongs to the technical field of metallurgical sheet production. A technical scheme of the method comprises the operations of smelting, LF refining, continuous casting, hot rolling, cold rolling and continuous annealing, and the steel comprises the following chemical components, by weight, 0.06-0.08% of C, 0.03% or less of Si, 1.3-1.5% of Mn, 0.4-0.5% of Cr, 0.025-0.055% of Als, 0.012% or less of P, 0.010% or less of S, and the balance Fe and inevitable impurities. The steel has the following practical performance ranges: the yield strength is 290-320MPa, the tensile strength is equal to or greater than 460MPa, and the elongation rate is equal to or greater than 29%. The method which allows the content of Si in the steel to be reduced and a Cr alloy to be properly added based on C-Mn steel has the advantages of avoiding of an automobile steel surface quality problem caused by the super-higher Si content in the practical production, low alloy cost, low production equipment requirements, good production continuity, and stable product quality, and is suitable for industrialized production.
Description
Technical field
The present invention relates to the working method that a kind of tensile strength is the 450MPa cold-rolled biphase steel, belong to the metallurgical plate production technical field.
Background technology
Safety and energy consumption become the subject matter that the countries in the world automotive industry faces, and high-strength vehicle is conducted oneself with dignity to alleviating vehicle body with the use of steel, improves component strength and has vital role.Is the basis with the phase transformation strengthening,, has characteristics such as low yield strength ratio, high initial manufacture hardening rate, good intensity and ductility cooperation, developed into the novel punching press of a kind of automobile high-strength and used steel by the dual phase steel that ferritic and martensite are formed.The high-strength steel that the increasing employing intensity of domestic car manufacturing enterprise is the 450MPa level, external high-grade automobile high-strength steel consumption has reached 60-70%.In view of good intensity and the impact briquetting of dual phase steel, become the focus of iron and steel enterprise's product development at present, external iron and steel enterprise carries out the dual phase steel research and development of different stage successively.In the background technology; Iron and steel enterprise is at the composition design aspect of dual phase steel; Main Si, Mn system or Si, Mn, the Cr system of adopting, the microalloying composition system of perhaps on C, Mn composition basis, adding Nb or Cr, Mo, B satisfies the requirement of varying strength through alloying element.The steel mill that for example both at home and abroad produces 450MPa level dual phase steel seldom, and in the design of the composition of the close trade mark 500MPa dual phase steel Si content general requirement 0.4%～1.0%, some in addition higher.And abroad certain motor corporation to use the Si-Mn-Cr-Mo composition be that the composition of 500MPa level dual phase steel is C=0.06%, Si=1.35%, Mn=0.09%, Cr=0.50%, Mo=0.35%, alloy species is more, cost is corresponding also to be improved.Show that through the actual industrial knowhow too high Si content will cause steel plate to produce in process of production such as surface quality problems such as hot-rolled sheet surface red phosphorus phenomenon, galvanized sheet surface plating leakages, thereby causes the production difficulty to strengthen and the quality product reduction.Simultaneously,, cause the production cost of steel plate to increase greatly, reduced the economy of product owing to added high price alloys such as more Mo, Cr in the part steel plate.
Summary of the invention
The object of the invention provides the working method that a kind of tensile strength is the 450MPa cold-rolled biphase steel, and cost of alloy is low, and is less demanding to production unit, and the production continuity is better, and constant product quality is fit to suitability for industrialized production, solves the problems referred to above that background technology exists.
Technical scheme of the present invention is:
A kind of tensile strength is the working method of 450MPa cold-rolled biphase steel, comprises smelting, LF refining, continuous casting, hot rolling, cold rolling company and moves back operation, and its chemical composition and weight percent are: C:0.06%～0.08%; Si :≤0.03%, Mn:1.3%～1.5%, Cr:0.4%～0.5%; Als:0.025%～0.055%; P :≤0.012%, S :≤0.010%, all the other are Fe and unavoidable impurities.
Said smelting procedure: the converter smelting that the coverter pig bottom blowing is good, omnidistance BOTTOM ARGON BLOWING; Blow off requires [C]≤0.05%, [P]＜0.01%, [S]≤0.008%; Forward and backward pushing off the slag during tapping, control is the quantity of slag down; Safeguard tap hole, guarantee steel stream rounding.
Said LF refining procedure: refining time is not less than 40 minutes, micro-pressure operation; Make the white slag operation in the refining process; Adopt mid-carbon fe-mn, ferrochrome to carry out the alloying operation; Carry out calcium and handle, line feeding finishes the back and guarantees to blow the time only greater than 5min; Forbid to blow cruelly in the treating processes and cause molten steel nitrogen pick-up.
Said continuous casting working procedure: continuous casting adopts protection cast, control process nitrogen pick-up; The surplus steel of middle bag is not less than 13t, and big bag remains steel and is not less than 10t; Nozzle quick-change, the unusual strand of liquid fluctuating are blocked inspection.
Said hot-rolled process: the hot rolling Heating temperature is 1210 ~ 1250 ℃, and Heating temperature and hot-rolled finished product thickness are complementary, and finishing temperature is 850 ~ 870 ℃, and coiling temperature is 635 ~ 665 ℃, and coiling temperature and hot-rolled finished product thickness specification are complementary.
Operation is moved back by said cold rolling company: even moving back soaking temperature is 810～830 ℃, and the slow cooling final cooling temperature is 650～670 ℃, and fast cold junction Shu Wendu is 290～310 ℃, and the completion of prescription temperature is 240～260 ℃; Belt speed is controlled between 76～170m/min, and belt speed control is complementary with product thickness; Smooth elongation control is within 0.5～1.1%, and smooth unit elongation and thickness are complementary.
Positively effect of the present invention: the present invention is through chemical ingredients, steel-making and the rolling technology of design DP450; DP450 finished product mechanical performance index is reached or be superior to GB; The actual performance scope is: ys 290～320MPa, tensile strength >=460MPa, unit elongation >=29%.The present invention passes through to reduce Si content in the steel on the basis of C-Mn steel; An amount of Cr alloy that adds, the surface quality problems of the automobile steel of avoiding causing because of silicone content is too high in the actual industrial production, cost of alloy is low; Less demanding to production unit; The production continuity is better, and constant product quality is fit to suitability for industrialized production.
Embodiment
Below through embodiment the present invention is described further.
In an embodiment, a kind of tensile strength is the working method of 450MPa cold-rolled biphase steel, comprises smelting, LF refining, continuous casting, hot rolling, cold rolling company and moves back operation; Its chemical composition and weight percent are: C:0.06%～0.08%, and Si :≤0.03%, Mn:1.3%～1.5%; Cr:0.4%～0.5%, Als:0.025%～0.055%, P :≤0.012%; S :≤0.010%, all the other are Fe and unavoidable impurities.
Each procedure technology step is following:
1, smelting procedure, LF refining procedure, continuous casting working procedure
Embodiment is as shown in table 1 with steel chemical composition.
Table 1 chemical ingredients (wt%)
Describe with embodiment one: the molten iron condition: molten iron [S] is 0.01%, steel scrap 8.3%, hot metal ratio 91.7%, 273 tons of target taps.Omnidistance Argon pattern is adopted in the converter bottom blowing.Basicity is controlled terminal point target [C] by 4.1: 0.036%, [P]: 0.007%, [S]: 0.008%.Pushing off the slag before the tapping before the tap hole outside adds floating plug and taps adds slag stop cone in the tap hole inboard before the tapping end and carries out the back pushing off the slag; The slag amount in the control tapping process inflow ladle and the ratio 0.6% of molten steel amount.Molten steel amount in converter tapping to the ladle reaches at 1/4 o'clock, adopts electrolytic manganese, medium carbon ferrochrome and magnalium calcium iron deoxidation alloying.Add lime during tapping to 1/3, lime improves the basicity of slag in the impact of high-temperature steel stream fusing and interact with molten steel down, and the oxidisability of reduction slag, the flowability of improving slag are that refining slag making desulfurization creates good conditions.
It is 43 minutes that the LF refining requires refining time, micro-pressure operation.Make the white slag operation in the refining process.Adopt mid-carbon fe-mn, ferrochrome to carry out the alloying operation.Carry out calcium and handle, line feeding finishes the back and guarantees to blow only time 6min.Molten steel composition before calcium is handled: [S] is 0.0080%, [Als]=450ppm, adopts pure calcium line to carry out calcium and handles operation, feeds calcium line and do not allow to add materials such as slag making material and reductor in preceding 5 minutes
Continuous casting requires continuous casting to adopt protection cast, control process nitrogen pick-up.Follow the principle that high temperature is poured into a mould at a slow speed, low temperature is poured into a mould fast, the pouring molten steel temperature is liquidus temperature+15-30 ℃.The speed control system of notes scope 0.9～1.6m/min.Nozzle quick-change, the unusual strand of liquid fluctuating are blocked inspection.
2, hot-rolled process
1230 ± 20 ℃ of Heating temperatures, heat-up time 40min, 860 ± 14 ℃ of finishing temperatures, 650 ± 17 ℃ of coiling temperatures.Concrete processing parameter is seen table 2.
Table 2 hot-rolled process parameter
3, operation is moved back by cold rolling company
The cold rolling trimmed size of this time producing is 1250 * 1.5mm, and cold rolling reel number is corresponding hot rolling reel number respectively, and annealing process is seen table 3.
Table 3 connects and to move back parameter (unit: ℃)
Smooth unit elongation unification is set according to 0.9%.
Be heated to the two-phase region insulation and make its partial austenitizing, in slowly cooling off subsequently, the ferritic elements such as helping carbon, manganese of separating out further shifts to austenite; Improved ferritic purity on the one hand; Improved austenitic hardening capacity on the other hand, the fast cold retained austenite that guaranteed forms the necessary martensite of dual phase steel and adds ferritic two-phase structure to martensitic transformation; The overaging section plays drawing effect to martensite, has further improved the comprehensive mechanical property of dual phase steel.
4, mechanical property
Mechanical property is seen table 4.
Table 4 mechanical property
Mechanical property satisfies the requirement of 450MPa level cold-rolled biphase steel fully in the table 4.
Claims (6)
1. working method that tensile strength is the 450MPa cold-rolled biphase steel is characterized in that comprising smelting, LF refining, continuous casting, hot rolling, cold rolling company and moves back operation, and its chemical composition and weight percent are: C:0.06%～0.08%; Si :≤0.03%, Mn:1.3%～1.5%, Cr:0.4%～0.5%; Als:0.025%～0.055%; P :≤0.012%, S :≤0.010%, all the other are Fe and unavoidable impurities.
2. the working method that is the 450MPa cold-rolled biphase steel according to the said a kind of tensile strength of claim 1; It is characterized in that said hot-rolled process: the hot rolling Heating temperature is 1210 ~ 1250 ℃; Heating temperature and hot-rolled finished product thickness are complementary; Finishing temperature is 850 ~ 870 ℃, and coiling temperature is 635 ~ 665 ℃, and coiling temperature and hot-rolled finished product thickness specification are complementary.
3. the working method that is the 450MPa cold-rolled biphase steel according to the said a kind of tensile strength of claim 2; It is characterized in that said cold rolling company moves back operation: connect that to move back soaking temperature be 810～830 ℃; The slow cooling final cooling temperature is 650～670 ℃; Fast cold junction Shu Wendu is 290～310 ℃, and the completion of prescription temperature is 240～260 ℃; Belt speed is controlled between 76～170m/min, and belt speed control is complementary with product thickness; Smooth elongation control is within 0.5～1.1%, and smooth unit elongation and thickness are complementary.
4. the working method that is the 450MPa cold-rolled biphase steel according to claim 1 or 2 said a kind of tensile strength is characterized in that said smelting procedure: the converter smelting that the coverter pig bottom blowing is good, omnidistance BOTTOM ARGON BLOWING; Blow off requires [C]≤0.05%, [P]＜0.01%, [S]≤0.008%; Forward and backward pushing off the slag during tapping, control is the quantity of slag down; Safeguard tap hole, guarantee steel stream rounding.
5. the working method that is the 450MPa cold-rolled biphase steel according to claim 1 or 2 said a kind of tensile strength, it is characterized in that said LF refining procedure: refining time is not less than 40 minutes, micro-pressure operation; Make the white slag operation in the refining process; Adopt mid-carbon fe-mn, ferrochrome to carry out the alloying operation; Carry out calcium and handle, line feeding finishes the back and guarantees to blow the time only greater than 5min.
6. the working method that is the 450MPa cold-rolled biphase steel according to the said a kind of tensile strength of claim 3 is characterized in that said continuous casting working procedure: continuous casting adopts protection cast, control process nitrogen pick-up.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103981452A (en) * | 2014-05-28 | 2014-08-13 | 江苏省沙钢钢铁研究院有限公司 | Economic air-cooled dual-phase low yield ratio steel plate and production process thereof |
| CN105401071A (en) * | 2015-12-22 | 2016-03-16 | 武汉钢铁(集团)公司 | Galvanized dual-phase steel for 500 MPa class car and production method |
| CN107267726A (en) * | 2017-06-06 | 2017-10-20 | 武汉钢铁有限公司 | The manufacture method of 450MPa grades of cold-rolled biphase steels of tensile strength |
| CN115584428A (en) * | 2022-11-07 | 2023-01-10 | 鞍钢股份有限公司 | Novel short-process low-cost cold-rolled DH590 steel and production method thereof |
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| KR20030055541A (en) * | 2001-12-27 | 2003-07-04 | 주식회사 포스코 | A Method of Manufacturing Hot-Rolled Sheet Having Superior Strength and Elongation |
| CN101781739A (en) * | 2010-03-18 | 2010-07-21 | 武汉钢铁(集团)公司 | Automobile cold-rolled dual-phase steel with tensile strength of 500 MPa |
| CN101942603A (en) * | 2010-09-28 | 2011-01-12 | 北京科技大学 | 600MPa-level ultra-low silicon cold rolling hot galvanizing dual-phase steel and preparation process thereof |
| CN102174683A (en) * | 2011-01-30 | 2011-09-07 | 首钢总公司 | Method for producing cold-rolling low-carbon aluminum killed steel with uniform through plate mechanical property |
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2012
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Patent Citations (4)
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| KR20030055541A (en) * | 2001-12-27 | 2003-07-04 | 주식회사 포스코 | A Method of Manufacturing Hot-Rolled Sheet Having Superior Strength and Elongation |
| CN101781739A (en) * | 2010-03-18 | 2010-07-21 | 武汉钢铁(集团)公司 | Automobile cold-rolled dual-phase steel with tensile strength of 500 MPa |
| CN101942603A (en) * | 2010-09-28 | 2011-01-12 | 北京科技大学 | 600MPa-level ultra-low silicon cold rolling hot galvanizing dual-phase steel and preparation process thereof |
| CN102174683A (en) * | 2011-01-30 | 2011-09-07 | 首钢总公司 | Method for producing cold-rolling low-carbon aluminum killed steel with uniform through plate mechanical property |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103981452A (en) * | 2014-05-28 | 2014-08-13 | 江苏省沙钢钢铁研究院有限公司 | Economic air-cooled dual-phase low yield ratio steel plate and production process thereof |
| CN103981452B (en) * | 2014-05-28 | 2016-03-09 | 江苏省沙钢钢铁研究院有限公司 | A kind of economical air cooling two-phase low yield strength ratio steel plate and production technique thereof |
| CN105401071A (en) * | 2015-12-22 | 2016-03-16 | 武汉钢铁(集团)公司 | Galvanized dual-phase steel for 500 MPa class car and production method |
| CN107267726A (en) * | 2017-06-06 | 2017-10-20 | 武汉钢铁有限公司 | The manufacture method of 450MPa grades of cold-rolled biphase steels of tensile strength |
| CN115584428A (en) * | 2022-11-07 | 2023-01-10 | 鞍钢股份有限公司 | Novel short-process low-cost cold-rolled DH590 steel and production method thereof |
| CN115584428B (en) * | 2022-11-07 | 2023-08-18 | 鞍钢股份有限公司 | Short-flow low-cost cold-rolled DH590 steel and production method thereof |
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Application publication date: 20121017 |