CN102534367A - Steel for superhigh-strength hot rolling automobile structure and preparation method thereof - Google Patents
Steel for superhigh-strength hot rolling automobile structure and preparation method thereof Download PDFInfo
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Abstract
The invention relates to steel for a superhigh-strength hot rolling automobile structure and a preparation method thereof, belonging to the field of alloy steel production processes. The steel comprises the following components: 0.08 percent to 0.12 percent of carbon, 0.10 percent to 0.50 percent of silicon, 1.5 percent to 2.50 percent of manganese, less than 0.02 percent of phosphorus, less than 0.01 percent of sulfur, 0.02 percent to 0.05 percent of aluminum, 0.08 to 0.25 percent of vanadium, 0.03 percent to 0.06 percent of nitrogen and the balance of Fe and other inevitable impurities. The production process comprises the following steps of: converter smelting; external refining; continuous casting; hot rolling and reeling. The main process parameters are as follows: the heating temperature of continuous casting slabs is between 1,150 and 1,220 DEG C, the reeling temperature is between 500 and 650 DEG C, and the hot rolling total reduction ratio is more than 85 percent. According to the steel, vanadium-nitride micro alloying is adopted, vanadium precipitation is promoted by enhancing nitrogen, grains are refined, and precipitation strengthening and fine-grain strengthening are used as main strengthening measures, so that the yield strength is more than 700 MPa, the tensile strength is more than 800 MPa, the total elongation rate after fracture is more than percent, and the steel is used for high-strength automobile structures with high plasticity and good cold bending properties.
Description
Technical field
The invention belongs to steel alloy production technique field, be applicable to, be specially adapted to production tensile strength greater than 800MPa, and have of the production of the superstrength vehicle structure of excellent toughness and plasticity with steel with the production of vanadium as the steel alloy of main strengthening element.
Background technology
The high-strength vehicle structural steel of domestic production at present; Generally all adopt alloying elements such as compound interpolation Nb, Ti, Mo to carry out microalloying; Its basic ideas adopt Nb to hinder the austenite recrystallization crystal grain thinning exactly; Adopt Ti and V etc. to carry out precipitation strength, adopt Mo to postpone perlitic transformation to obtain enhanced tissues such as bainite or ferritic.The microalloy amount that such mode of production is added is more, higher to the controlled rolling and controlled cooling technical requirements simultaneously, and product performance are comparatively responsive to technology, and it is bigger to fluctuate, and cost is higher.On the basis of carbon manganese steel, add vanadium and nitrogen separately and carry out microalloying,, therefore realize continuous casting relatively easily because vanadium is the easiest solid solution in the micro alloying element, and is not prone to transverse crack.In addition, because that temperature is separated out in the solid solution of microalloy element V is lower, therefore, the Heating temperature that needs is lower, therefore, can produce under the close condition at the C-Mn steel and produce.Containing the V steel can produce through the recrystallize controlled rolling, and its rolling temperature is higher, needn't improve armor plate strength through reducing finishing temperature, therefore, need not increase considerably mill load, and the relative finishing temperature of its mechanical property is insensitive.
The V-N micro-alloying technology is mainly used in the production of high strength cast iron at home at present, climbs steel research and development v n micro alloying 500MPa grade high-strength reinforcing bar; The ys of Germany's exploitation is that 500MPa grade high-strength degree reinforcing bar has adopted the v n micro alloying technology.The V-N micro-alloying technology is used in vehicle structure with also being in the starting stage in the production of steel.
The CSP corporate boss of North America will utilize the precipitation strength effect of V-N microalloying, and the main strengthening mechanism of the V-N micro-alloyed steel of being developed is the precipitation strength of V.The composition and the performance of its product are as shown in table 1.The ferrite grain size of its product is bigger, and strength level is lower, and tensile strength only reaches about 600MPa.
Table 1 North America thin slab is produced the composition and the performance of V-N steel
| Test piece number (Test pc No.) | Thickness of strips | C/wt% | Si/wt% | Mn/wt% | Al/wt% | V/wt% | N/wt% | Rel/MPa | Rm/MPa | A/% |
| A-11 | 12.6 | 0.064 | 0.01 | 1.01 | 0.039 | 0.065 | 0.014 | 425 | 505 | 33 |
| A-12 | 7.8 | 0.053 | 0.01 | 0.99 | 0.036 | 0.067 | 0.156 | 506 | 529 | 31 |
| A-13 | 2.1 | 0.056 | 0.03 | 0.78 | 0.036 | 0.058 | 0.136 | 425 | 485 | 32 |
| A-14 | 3.8 | 0.058 | 0.02 | 0.86 | 0.037 | 0.086 | 0.0163 | 444 | 555 | 28 |
| A-15 | 6.3 | 0.05 | 0.01 | 0.8 | 0.05 | 0.057 | 0.0146 | 396 | 496 | 29 |
| B-1 | 2 | 0.054 | 0.19 | 0.99 | 0.024 | 0.05 | 0.015 | 442 | 517 | 28 |
| B-2 | 7.6 | 0.051 | 0.2 | 0.97 | 0.0 | 0.046 | 0.014 | 399 | 506 | 33 |
| C-3 | 5.7 | 0.052 | 0.36 | 1.58 | 0.026 | 0.12 | 0.02 | 536 | 627 | 30 |
Chinese patent 200510100421.2 has utilized the CSP line development vanadium nitrogen microalloy hot rolled thin strip of intensity rank for 400-700MPa.The chemical ingredients scope is: C:0.03-0.08wt%; Si:0.01-0.8wt%; Mn:0.1-2.0wt%; V:0.01-2.0wt%; N:0.002-0.03wt%, it makes steel plate organize obvious refinement through process optimization control, strength level obviously improves.But its technical process is a sheet billet continuous casting and rolling production line, and being applied to promote of production technique has certain limitation.Simultaneously, with respect to conventional process flow, because its microalloy element does not have to separate out-dissolve-process separated out; Bring into play the high solid solution advantage of microalloy element more easily; The slab thickness that it is thin, the speed of cooling of thin slab in mold and the condensing surface slab under the traditional technology has reduced thick dendrite; So its secondary, three dendrite intervals are shorter; Thereby obtain shape comparatively rule, the original as-cast structure of size tiny and uniform, the armor plate strength that the technology for controlled cooling of the controlled rolling of heavy reduction rate and optimization, thereby continuous casting and rolling technique of sheet bar is in addition produced is generally higher.
Summary of the invention
The present invention seeks to mate corresponding production technique through the V-N microalloying comes the superstrength vehicle structure of crystal grain thinning raising intensity to use steel; This technology controlling of production process is simple; Reduction is to the requirement of processing unit, and the superstrength vehicle structure with excellent toughness and cold-bending property that availability is stable is used steel plate.
A kind of superelevation heat-flash rolls vehicle structure and uses steel, it is characterized in that steel chemical composition (wt%) is: C:0.08%～0.12%; Si:0.10%～0.50%; Mn:1.50%～2.50%; P＜0.02%; S＜0.01%; Alt:0.02%～0.05%; V:0.08～0.25%; N:0.03%～0.06%; All the other are Fe and other unavoidable impurities.
The strong vehicle structure of described superelevation is characterized in that with the preparation method of steel following main technologic parameters is: 1150-1220 ℃ of continuous casting steel billet Heating temperature is incubated 0.5-1 hour; Start rolling temperature 1100-1180 ℃, finishing temperature 850-1000 ℃, coiling temperature 500-650 ℃; The total draft of hot rolling is greater than 85%; The main v n micro alloying that adopts promotes vanadium to separate out crystal grain thinning simultaneously through nitrogen pick-up, is main reinforcement means with precipitation strength and refined crystalline strengthening; Obtain ys greater than 700MPa, tensile strength is used steel greater than the superstrength vehicle structure of 800MPa.
The strong vehicle structure of described superelevation is used composition of steel, through improving nitrogen in steel content, adopts v n micro alloying, has promoted that tiny carbon vanadium nitride particle disperse in steel is separated out in the steel, and the precipitation strength effect is obviously strengthened; Enlarged the TR of separating out of two-phase particle, the second phase particle of separating out in the operation of rolling has played the effect of thinning microstructure, has improved the effect of V steel cooling controlling and rolling controlling process to steel plate structure refinement and reinforcement that contain.In addition, carbon vanadium nitride particle can promote ferritic forming core, obviously refinement ferrite crystal grain, thereby significantly improve the intensity and the toughness of steel plate.
Through adopting controlled rolling; Separating out the finish to gauge of nose temperature, and strengthening and roll postcooling speed, the final microstructure of refinement; Make that the ferritic average grain size is less than 5 microns in the steel; Promote separating out of nano level two-phase particle in the steel, the size of the two-phase particle that disperse is separated out is less than 10nm, thereby reaches the target strength of superstrength vehicle structure with steel.
Technical characterstic of the present invention is following:
(1) promotes separating out of vanadium through nitrogen pick-up, strengthen precipitation strength and refined crystalline strengthening effect
The present invention separates out thermodynamics and dynamics through molten steel nitrogen pick-up is improved vanadium, strengthens V and separates out ratio, strengthens precipitating reinforcing effect.Select lower Heating temperature and soaking time, make that microalloy element dissolves fully in the steel, to increase the vanadium ratio of precipitated phase.
(2) adopt the controlled rolling of two stages
The present invention adopts conventional hot rolling line, adopts two stage rolling to get final product, and can take into account the production of other hot-rolled product.Give and certain draught through the recrystallization zone, promote that V separates out in the high temperature austenite district, hinder austenite recrystallization, the refinement original austenite grains; The district gives heavy reduction at non-recrystallization, and the small and dispersed of carbonitride is separated out when promoting phase transformation.Precipitate is to help to induce intracrystalline ferritic forming core, further crystal grain thinning in the ferrite transformation process at austenitic transformation simultaneously.
(3) adopt rational cooling system and coiling technique to make and separate out the ratio maximization
Through rational controlled rolling and technology for controlled cooling; Control the opportunity of separating out and separate out the quantity and the size of two-phase particle; The present invention has explored a kind of best coiling temperature system and technology, has lowered traditional technology and has produced the requirement of high-strength steel to equipment, and the product comprehensive mechanical property of acquisition is best.
Compared with prior art, advantage of the present invention:
1 pair of equipment requirements is lower
The present invention adopts conventional equipment of hot rolling can satisfy working condition.Slab heating temperature is low, save energy.Finishing temperature is higher, and required rolling load is lower, also can cut down the consumption of energy.
2 technology susceptibilitys are low
The present invention adopts V-N microalloying production superelevation heat-flash to roll automobile steel and since vanadium mainly be the interval section of lesser temps promptly the stage of batching separate out, thereby hot rolling technology is less to the performance impact of V-N steel, can select for use flexibly according to field condition.
3 grain refinings, product reaming and cold-bending property are good
The present invention adopts V-N microalloying production superelevation heat-flash to roll automobile steel, promotes vanadium to separate out in the austenitic area through nitrogen pick-up, hinders austenite and grows up; The forming core point of austenite to ferritic transformation is provided simultaneously, improves nucleation rate, refinement ferrite crystal grain, the average ferrite grain size of product are less than 5 microns, and the surface layer grain size is compared traditional high-strength steel less than 2 microns, and microstructure is refinement greatly.Improved intensity and toughness greatly on the one hand, also improved clod wash and reaming performance on the other hand, even if when nitrogen content is higher, cold-bending property still can be up to standard.
4 precipitating reinforcing effects
Compare conventional low nitrogen vanadium steel, the vanadium major part is in precipitation state in the V-N microalloyed steel, and the amount of separating out of vanadium improves more than 30%, and the precipitation particles size obviously reduces, and through the practicality that nitrogen pick-up can be practiced thrift vanadium, has the higher cost advantage.
Description of drawings
Fig. 1 is a typical two-phase particle morphology in the steel
Embodiment:
Embodiment 1:
Molten steel chemical ingredients (wt%): C:0.09-0.11%; Si:0.25-0.40%; Mn:1.50-2.0%; V:0.10-0.15%; N:0.03-0.05%.
Hot-rolled process parameter is: continuous blank heating temperature 1150-1200 ℃; Start rolling temperature: 1120-1150 ℃; Finishing temperature: 850-920 ℃; Coiling temperature 580-610 ℃.
The mechanical property of steel plate is as shown in table 2.Typical two-phase particle is as shown in Figure 1 in the steel.
The mechanical property of table 2 embodiment 1
| Product thickness/mm | Rel/MPa | Rm/MPa | A/% | 180 ° of clod washes, b=35mm, d=a |
| 5.0 | 725 | 835 | 25 | Qualified |
| 8.0 | 745 | 815 | 23 | Qualified |
Embodiment 2:
Molten steel chemical ingredients (wt%): C:0.10-0.12%; Si:0.30-0.50%; Mn:1.50-2.0%; V:0.13-0.20%; N:0.04-0.06%.
Hot-rolled process parameter is: continuous blank heating temperature 1150-1200 ℃; Start rolling temperature: 1120-1150 ℃; Finishing temperature: 860-930 ℃; Coiling temperature 580-610 ℃.
The mechanical property of steel plate is as shown in table 3.
The mechanical property of table 3 embodiment 2
| Product thickness/mm | Rel/MPa | Rm/MPa | A/% | 180 ° of clod washes, b=35mm, d=a |
| 4.5 | 750 | 865 | 22 | Qualified |
| 6.0 | 765 | 880 | 22 | Qualified |
Claims (2)
1. a superelevation heat-flash rolls vehicle structure and uses steel, it is characterized in that steel chemical composition (wt%) is: C:0.08%～0.12%; Si:0.10%～0.50%; Mn:1.50%～2.50%; P＜0.02%; S＜0.01%; Alt:0.02%～0.05%; V:0.08～0.25%; N:0.03%～0.06%; All the other are Fe and other unavoidable impurities.
2. according to the preparation method of the strong vehicle structure of the described superelevation of claim 1 with steel, it is characterized in that following main technologic parameters is: 1150-1220 ℃ of continuous casting steel billet Heating temperature is incubated 0.5-1 hour; Start rolling temperature 1100-1180 ℃, finishing temperature 850-1000 ℃, coiling temperature 500-650 ℃; The total draft of hot rolling is greater than 85%; The main v n micro alloying that adopts promotes vanadium to separate out crystal grain thinning simultaneously through nitrogen pick-up, is main reinforcement means with precipitation strength and refined crystalline strengthening; Obtain ys greater than 700MPa, tensile strength is used steel greater than the superstrength vehicle structure of 800MPa.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104561791A (en) * | 2015-01-28 | 2015-04-29 | 河北钢铁股份有限公司承德分公司 | 800MPa grade automobile box steel and production method thereof |
| CN104550898A (en) * | 2014-12-27 | 2015-04-29 | 首钢总公司 | Nitrogen increment method for vanadium-nitrogen microalloying steel grade in continuous casting process |
| CN110747322A (en) * | 2019-09-26 | 2020-02-04 | 中国电力科学研究院有限公司 | 1180MPa nanoparticle reinforced ferrite steel and preparation method thereof |
| CN113755762A (en) * | 2021-09-18 | 2021-12-07 | 太原理工大学 | Low-V microalloyed ultra-fine dispersion precipitated phase high-strength steel and preparation method thereof |
| CN113930677A (en) * | 2021-09-24 | 2022-01-14 | 首钢集团有限公司 | Steel belt for packaging and production method thereof |
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| CN1748883A (en) * | 2005-10-20 | 2006-03-22 | 广州珠江钢铁有限责任公司 | Process for producing V-N micro alloy high strength steel band using thin plate blank continuously casting and continuously rolling technology |
| CN1884608A (en) * | 2006-06-06 | 2006-12-27 | 广州珠江钢铁有限责任公司 | Method for producing 700Mpa V-N microalloyed high-strength air corrosion-resistant steel based on sheet bar continuous casting tandem rolling process |
| CN101161843A (en) * | 2007-11-21 | 2008-04-16 | 广州珠江钢铁有限责任公司 | Method for improving utilization ratio of V-N micro-alloying high-strength steel vanadium alloy |
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2011
- 2011-12-02 CN CN2011103976106A patent/CN102534367A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1748883A (en) * | 2005-10-20 | 2006-03-22 | 广州珠江钢铁有限责任公司 | Process for producing V-N micro alloy high strength steel band using thin plate blank continuously casting and continuously rolling technology |
| CN1884608A (en) * | 2006-06-06 | 2006-12-27 | 广州珠江钢铁有限责任公司 | Method for producing 700Mpa V-N microalloyed high-strength air corrosion-resistant steel based on sheet bar continuous casting tandem rolling process |
| CN101161843A (en) * | 2007-11-21 | 2008-04-16 | 广州珠江钢铁有限责任公司 | Method for improving utilization ratio of V-N micro-alloying high-strength steel vanadium alloy |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104550898A (en) * | 2014-12-27 | 2015-04-29 | 首钢总公司 | Nitrogen increment method for vanadium-nitrogen microalloying steel grade in continuous casting process |
| CN104561791A (en) * | 2015-01-28 | 2015-04-29 | 河北钢铁股份有限公司承德分公司 | 800MPa grade automobile box steel and production method thereof |
| CN110747322A (en) * | 2019-09-26 | 2020-02-04 | 中国电力科学研究院有限公司 | 1180MPa nanoparticle reinforced ferrite steel and preparation method thereof |
| CN113755762A (en) * | 2021-09-18 | 2021-12-07 | 太原理工大学 | Low-V microalloyed ultra-fine dispersion precipitated phase high-strength steel and preparation method thereof |
| CN113930677A (en) * | 2021-09-24 | 2022-01-14 | 首钢集团有限公司 | Steel belt for packaging and production method thereof |
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Application publication date: 20120704 |