CN101768698B - Low cost yield strength 700MPA level non-tempering processing high strength steel plate and manufacturing method thereof - Google Patents

Low cost yield strength 700MPA level non-tempering processing high strength steel plate and manufacturing method thereof Download PDF

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CN101768698B
CN101768698B CN2010101018150A CN201010101815A CN101768698B CN 101768698 B CN101768698 B CN 101768698B CN 2010101018150 A CN2010101018150 A CN 2010101018150A CN 201010101815 A CN201010101815 A CN 201010101815A CN 101768698 B CN101768698 B CN 101768698B
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rolling
strength
steel
temperature
steel plate
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CN2010101018150A
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CN101768698A (en
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赵培林
孙新军
孙其家
陈爱娇
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莱芜钢铁股份有限公司
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Abstract

The invention discloses a low cost yield strength 700MPA level non-tempering processing high strength steel plate, which is characterized by, in terms of mass, comprising 0.05-0.10% of C, 0.1-0.4% of Si, 1.5-2.0% of Mn, less than 0.015% of P, less than 0.01% of S, 0.3-0.8% of Cr, 0.09-0.15% of Ti, 0.04-0.08% of Nb, less than 0.005% of N, less than 0.002% of O, and balance of Fe and unavoidable impurities. The manufacturing method of the steel plate comprises technological steps of smelting, rough rolling, fine rolling, reeling and cooling to obtain the steel plate with yield strength of 700-780MPa, tensile strength of 800-860MPa and elongation Delta larger than or equal to 18%. The yield strength 700MPA level non-tempering processing high strength steel plate simultaneously has abrasive resistance and better low temperature toughness, toughness and crispiness transition temperature is at around negative 40 DEG C, specific energy of shock at normal temperature can reach as high as 120J.

Description

A kind of low cost yield strength 700 MPA level non-tempering processing high strength steel plate and manufacture method thereof

Technical field

The present invention relates to the manufacture method of the not non-modifier treatment High Strength Steel Plate of a kind of low-cost Yield strength 700 MPa grade, belong to hot-rolling high-strength steel plate production technical field.

Background technology

What the steel grade of the 700MPa intensity rank that present different enterprise produces adopted is the thought of alloying, the alloying constituent difference that different enterprises adopts, and the alloy amount is also different.Along with society and expanding economy, the pressure of the saving resource that Iron And Steel Industry faced, save energy, protection environment is increasing.Both at home and abroad when producing the 700MPa steel, not only caused the increase of steel product cost at present, the difficulty, the especially rare elements that increase the recycling that has also increased the steel later stages of alloying element simultaneously are such as the Mo that often adds etc.

Producing the 700Mpa steel both at home and abroad adopts different technology to carry out processing.

Nippon Steel Manufacturing Corp's publication number is weathering resistance high tensile steel plate and the manufacture method thereof that the patent documentation of CN1639371 discloses a kind of has excellent bending properties, the steel plate and the manufacture method thereof of time property.The weathering resistance high tensile steel plate of described has excellent bending properties contains C:0.05~0.15% in mass; Si:0.5% or following; Mn:1.5~2.0%; P:<0.02%; S:<0.005%; Ni:0.2-2.0%; Cu:0.2-0.5%; Cr:0.2~1.0%; And contain Ti:0.03~0.2%; Nb:0.01~0.07%; V:0.01-0.07%; Among the B:0.0005-0.005% a kind, 2 kinds or more than, surplus is Fe and unavoidable impurities.This technical scheme is added the Ni large percentage, and cost increases greatly on the one hand, and one side Ni controls improperly and will make the steel surface produce iron scale under the situation in addition, influences surface quality.

The publication number of Baoshan Iron ﹠ Steel Co., Ltd is the patent documentation of CN101153371, relates to a kind of high-strength cold-formed hot continuous rolled steel plate and production method thereof.Its chemical ingredients is as follows: C:0.05~0.10wt%, Si:0.10~0.50wt%, Mn:1.0~2.0wt%, P≤0.025wt%, S≤0.010wt%, Nb:0.03~0.08wt%, Ti:0.05~0.15wt%, Mo:0.10~0.50wt%, Ca:0.0010~0.0050wt%, Al:0.01~0.05wt%, all the other are Fe and unavoidable impurities.Its technical process comprises: the dark desulfurization of molten iron → converter top bottom blowing → external refining → continuous casting (machine is clear) → hot-loading and hot-conveying advances holding pit → slab reheat → controlled rolling → controlled chilling → batch → finishing.The adding and the lower cooling temperature of later stage of alloying element such as Mo in this technical scheme have not only improved the cost of steel, have also improved the carbon equivalent and the crackle sensitivity coefficient of steel, and its processability is had disadvantageous effect.

The publication number of Northeastern University is the manufacture method that relates to a kind of 700MPa level F/B high strength band steel in the patent documentation of CN1757783, main points are that the chemical composition weight percent of apolegamy steel is: C:0.12-0.18, Si :≤0.1, Mn:1.60-2.20, Ti:0.15-0.22, P:<0.01, S:<0.01, all the other are iron Fe, carry out following cooling controlling and rolling controlling process system: the continuous casting steel billet Heating temperature is 1200 ℃, the roughing start rolling temperature is 1150 ℃, the roughing finishing temperature is 1050 ℃, and middle steel billet thickness is 32-45mm, and the finish rolling start rolling temperature is 1000-950 ℃, the finish rolling finishing temperature is 790-850 ℃, water-cooled between finishing stand; Rolling postcooling speed is 30-50 ℃/s, batches at 450-600 ℃.The most of heterogeneous structure for the bainite structure of refinement and a little ferrite of this application high strength band steel metallographic structure, final rolling temperature are crossed to hang down and have been caused very big difficulty to situ production, and the control of bainite structure content is also very difficult.Single high Ti handles, and the microalloying effect reduces greatly, and cast is the difficult control of separating out of TiN.

Summary of the invention

The objective of the invention is in order to save resource, reduce and smelt difficulty, make that simultaneously the steel band of producing satisfies more than the Yield strength 700 MPa, a kind of low cost yield strength 700 MPA level non-tempering processing high strength steel plate and manufacture method thereof are provided, be on the basis of carbon manganese structure iron composition, by adding an amount of microalloy element and adopting the controlled rolling and controlled cooling technology, the production yield strength is more than 700MPa, tensile strength is more than 780MPa, unit elongation has the steel band of good cold forming capability simultaneously more than 16%.

Technical scheme of the present invention is: a kind of low cost yield strength 700 MPA level non-tempering processing high strength steel plate is characterized in that: contain C:0.05~0.10% in mass; Si:0.1%~0.4%; Mn:1.5~2.0%; P<0.015%; S<0.01%; Cr:0.3~0.8%; Ti:0.09~0.15%; Nb:0.04~0.08%; N:<0.005%; O:<0.002%; All the other are iron Fe and unavoidable impurities.

Above-mentioned low cost yield strength 700 MPA level non-tempering processing high strength steel plate, yield strength: 700~780MPa; Tensile strength: 800~860MPa, unit elongation δ 〉=18%.

A kind of manufacture method of above-mentioned steel plate: it is characterized in that step is as follows:

1) smelt: comprise the chemical ingredients of matching high-strength steel, the continuous casting steel billet processing step, its main points are: the chemical composition of apolegamy high-strength steel, smelt in converter, refining furnace was handled 30~40 minutes, and impurity and gas content in the strict control steel carry out continuous casting subsequently and become strand;

2) roll forming technology: adopt the controlled rolling and controlled cooling pattern, to the continuous casting steel billet heating, Heating temperature is 1200~1250 ℃, afterwards carried out controlled rolling at 120~150 minutes heat-up time, and the roughing start rolling temperature is 1160 ℃, the roughing finishing temperature is 1060 ℃, and it is rolling that the roughing process is carried out 5 passages; The finish rolling start rolling temperature is 1060~1020 ℃, and the finish rolling finishing temperature is 850~950 ℃, and it is rolling that the finish rolling process is carried out 4~6 passages, adopts water-cooled between finishing stand;

3) coiling technique and cooling system: blank behind the rolling is carried out the laminar flow cooling, speed of cooling is 20~50 ℃/S, and coiling temperature is 540~600 ℃, and above-mentioned continuous casting steel billet is through after the roughing, middle sotck thinkness is 28~40mm, and final product thickness is 3~10mm; According to different final thickness sizes, every time draught of finish rolling process is controlled at 15~40%.

To above-mentioned continuous casting material be in the austenite recrystallization district, non-recrystallization district and the controlled rolling of deformation induced phase change zone.By the austenite recrystallization controlled rolling of high-temperature zone, abundant refine austenite crystal grain; By water-cooled between the passage in finish rolling stage, reduce the rolled piece temperature, increase the distortion in austenite non-recrystallization district; The finish rolling finishing temperature is controlled at 850~950 ℃, makes the bigger accumulation strain of generation in the operation of rolling; By rolling batching of quick cooling in back and mild temperature, obtain the polygonal ferrite of ultra-fine 3~5 μ m and account for 5~10% bainite composition.

The invention has the beneficial effects as follows: 1) the present invention has adopted low-cost composition design, replace expensive alloying element Ni with higher Cr content, precious metal elements such as Mo, by refined crystalline strengthening and precipitation strength effect, make yield strength reach more than the 700MPa, increased wear resistance simultaneously, therefore, cost reduces obviously.2) steel band of the present invention has the polygonal ferrite tissue of super-refinement, makes material have higher intensity and good plasticity, and the toughness of material is improved simultaneously.An amount of granular bainite can effectively improve tensile strength, improves work hardening capacity, reduces yield tensile ratio, makes material when improving intensity, also has good cold formability.3) low-temperature flexibility of material is better, and ductile-brittle transition temperature is about-40 ℃, and the normal temperature Charpy-V impact power can reach more than the 120J.4) the high-strength steel band of the present invention can reach following over-all properties: yield strength: 700~780MPa; Tensile strength: 800~860MPa, unit elongation δ 〉=18%.

Below describe the present invention:

1) C: carbon can improve the intensity of steel, and hardness is main gap solution strengthening element.Adopt the low-carbon (LC) composition design method can not only guarantee plasticity and the toughness that little Yu Gangyou of closing is good, and can improve the hot and cold deformability of steel effectively.Simultaneously, along with the reduction of carbon content and the reduction of carbon equivalent, can make micro-alloyed steel can keep good weldability and low ductile-brittle transition temperature.When rolling postcooling to low temperature, (Nb, Ti) C play important precipitation strength and use can to form tiny carbide with Ti and Nb.Carbon content is higher than 0.1%, although can improve intensity, can cause cold forming capability and welding property to reduce greatly.Carbon content is crossed the low increase greatly that can cause cost, and brings harsh requirement for the interpolation of alloys such as Mn.

2) Mn:Mn can reduce the transformation temperature of austenite to ferritic transformation, and austenite has refining effect to the reduction of the transformation temperature of ferritic transformation for the ferrite grain size of hot rolling attitude or normalizing attitude steel, therefore, Mn is widely used as the main alloy element in the high strength microalloy steel for a long time.The too high crack sensitivity that will increase of Mn significantly increases, and low excessively then solid solution strengthening effect is not obvious, thereby influences strength property.So the span of Mn is determined 1.5~2.0%.

3) Si: can solid solution in ferrite and austenite, improve intensity, hardness, elasticity and the wear resistance of steel.Improve quenching, normalizing and the annealing temperature of steel, improve the temper resistance and the oxidation-resistance of steel.When Si content was higher in the steel, the welding property of steel can worsen.Si content is higher than toughness and the plasticity that will damage steel more than 0.5%.

4) Cr: chromium can improve intensity and the hardness and the wear resistance of steel.Chromium adds the high-temperature oxidation resistance (non-scale) that can significantly improve steel in the steel, significantly improves the hardening capacity of steel, improves the anti-temper resistance of steel.On the other hand, chromium also can promote the temper brittleness tendency of steel.Cr content is lower than at 0.3% o'clock, and anti-wear-resisting effect is relatively poor.Be higher than at 0.8% o'clock, unfavorable to hardening capacity, the delayed fracture of steel.The useful range of Cr is 0.3~0.8% in this steel.

5) Nb: be important micro alloying element, can improve the non-recrystallization district temperature of steel, ensure the effect of controlled rolling, make grain refining after the Steel Rolling, Nb rolling later stage of NbC precipitation particles of separating out has the precipitation strength effect simultaneously.Experiment shows that the scope in this steel is 0.04%~0.08%, best results.The too high or too low then DeGrain of content.

6) Ti: be precipitation strength element important among the present invention, separate out TiN during high temperature, effectively stop AUSTENITE GRAIN COARSENING.Below 600 ℃, precipitation is separated out and is nanometer TIC or (Nb, Ti) C particle, effective pinning dislocation, thereby raising yield strength from steel.Experiment shows that it is less than 0.09%, separates out precipitation strength effect deficiency.Form crack defect at casting billet surface when being higher than 0.15% continuous casting; Under quick refrigerative prerequisite, its precipitation strength effect also is tending towards saturated, selects its span of control 0.09%~0.15% simultaneously.

On basis according to the mentioned component design, the cooling controlling and rolling controlling process that adopts, heating process adopts heat, and Heating temperature is more than 1200 ℃, heat-up time, the cold and hot degree difference according to strand suitably was controlled at 120~150 minutes, was beneficial to the abundant solid solution of alloying element like this.Finish rolling is carried out under 900~1080 ℃, and the rolling alloying element that can reduce of comparatively high temps is in too early the separating out from austenite of controlled rolling process; Simultaneously, coiling temperature adopts 500 ℃~600 ℃, to obtain the best precipitation strength effect of separating out.

Embodiment

The present invention will be described below to enumerate specific embodiment.It is pointed out that embodiment only is used for that the invention will be further described, do not represent protection scope of the present invention, nonessential modification and adjustment that other people make according to the present invention still belong to protection scope of the present invention.

The chemical ingredients scope of setting according to the present invention, following embodiment is by following concrete technical process: with chemical ingredients C, Si, Mn, S, P and Fe are raw material, carry out electric furnace or converter smelting, refining process molten steel is carried out Alloying Treatment, continuous casting, strand direct heating or soaking, hot continuous rolling, rolls back laminar flow water cooling, flow preparation such as batches and form.

List following two forms according to experimental result, compare with all the other inventions disclosed, carry out comprehensive comparative analysis and explanation at the embodiment of the invention.

Table 1

As can be seen from Table 1, the present invention has adopted composition design cheaply, replaces Ni with Ti, elements such as Mo, the present invention add alloying element simple, the chemical ingredients cost is lower, simultaneously, avoids single interpolation Ti element, well brought into play Nb, the combined microalloying effect of Ti element, on-the-spot working control are got up simply, and be easy to operate.

As can be seen from Table 2, Heating temperature of the present invention and finishing temperature realize rolling relatively easy than other patent height for general hot rolls.Simultaneously, the composition design cost of employing is lower, can guarantee the yield strength of this steel band, and unit elongation etc. all are not less than other inventions.

Table 2

In sum, utilize the parameter value in the technical scheme of the present invention can reach purpose of the present invention.Over-all properties: yield strength: 700~780MPa; Tensile strength: 800~860MPa, unit elongation δ 〉=18%.

Claims (1)

1. the manufacture method of the non-modifier treatment High Strength Steel Plate of low-cost Yield strength 700 MPa grade contains C:0.05~0.10% in mass; Si:0.1%~0.4%; Mn:1.5~2.0%; P<0.015%; S<0.01%; Cr:0.3~0.8%; Ti:0.09~0.15%; Nb:0.04~0.08%; N:<0.005%; O:<0.002%; All the other are iron Fe and unavoidable impurities; Above-mentioned steel plate yield strength: 700~780MPa; Tensile strength: 800~860MPa; Unit elongation: δ 〉=18% is characterized in that step is as follows:
1) smelt: comprise the chemical ingredients of matching high-strength steel, the continuous casting steel billet processing step, its main points are: the chemical composition of apolegamy high-strength steel, smelt in converter, refining furnace was handled 30~40 minutes, and impurity and gas content in the strict control steel carry out continuous casting subsequently and become strand;
2) roll forming technology: adopt the controlled rolling and controlled cooling pattern, to the continuous casting steel billet heating, Heating temperature is 1200~1250 ℃, and heat-up time was at 120~150 minutes; Carry out controlled rolling afterwards, the roughing start rolling temperature is 1160 ℃, and the roughing finishing temperature is 1060 ℃, it is rolling that the roughing process is carried out 5 passages, and the finish rolling start rolling temperature is 1060~1020 ℃, and the finish rolling finishing temperature is 850~950 ℃, it is rolling that the finish rolling process is carried out 4~6 passages, adopts water-cooled between finishing stand;
3) coiling technique and cooling system: blank behind the rolling is carried out the laminar flow cooling, speed of cooling is 20~50 ℃/S, and coiling temperature is 540~600 ℃, and above-mentioned continuous casting steel billet is through after the roughing, middle sotck thinkness is 28~40mm, and final product thickness is 3~10mm; According to different final thickness sizes, every time draught of finish rolling process is controlled at 15~40%.
CN2010101018150A 2010-01-27 2010-01-27 Low cost yield strength 700MPA level non-tempering processing high strength steel plate and manufacturing method thereof CN101768698B (en)

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CN101956141A (en) * 2010-10-08 2011-01-26 莱芜钢铁股份有限公司 Low-cost non-quenched and tempered high-strength wear-resistant steal plate with yield strength of 780 MPa grade and manufacturing method thereof
CN103122435A (en) * 2011-11-18 2013-05-29 江苏省沙钢钢铁研究院有限公司 Hot-rolled titaniferous high-strength steel plate with yield strength higher than 700MPa and production method thereof
CN103774050A (en) * 2012-10-25 2014-05-07 吴雪 High-ductility steel with low yield ratio
CN103773935A (en) * 2012-10-25 2014-05-07 吴雪 Process for rolling low yield ratio and high plasticity steel plate with thickness of 40 nm
CN103774052A (en) * 2012-10-25 2014-05-07 吴雪 Method for preparing high-strength steel plate with thickness of 20 mm
CN103031419B (en) * 2012-12-24 2015-05-27 首钢总公司 Method for improving performance uniformity of steel roll of Ti microalloyed high strength machinery
CN103320717B (en) * 2013-06-04 2015-07-22 南京钢铁股份有限公司 Ultra high-strength high titanium steel plate with yield strength of 960 MPa and preparing method of same
CN103388109A (en) * 2013-07-10 2013-11-13 内蒙古包钢钢联股份有限公司 500 MPa grade superfine crystal steel for engineering machinery and preparation method thereof
TWI509087B (en) * 2014-07-21 2015-11-21 China Steel Corp High strength hot rolled steel
CN104498690B (en) * 2015-01-12 2016-08-17 武汉科技大学 A kind of hot-rolled high-strength micro alloyed steel and preparation method thereof
CN107058898A (en) * 2017-03-31 2017-08-18 河钢股份有限公司邯郸分公司 A kind of Q690D low-carbon bainite steels and its production method
CN108246801B (en) * 2017-12-29 2020-12-08 钢铁研究总院华东分院 Large-size non-quenched and tempered steel rolling equipment and rolling production method thereof
CN111286675A (en) * 2020-03-31 2020-06-16 湖南华菱湘潭钢铁有限公司 Production method of X80 hot rolled steel plate for large-caliber hot-bending pipe

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