CN100420769C - Rolling controlled and cooling controlled steel for hydraulic power station penstock and manufacture method thereof - Google Patents
Rolling controlled and cooling controlled steel for hydraulic power station penstock and manufacture method thereof Download PDFInfo
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- CN100420769C CN100420769C CNB2006100200380A CN200610020038A CN100420769C CN 100420769 C CN100420769 C CN 100420769C CN B2006100200380 A CNB2006100200380 A CN B2006100200380A CN 200610020038 A CN200610020038 A CN 200610020038A CN 100420769 C CN100420769 C CN 100420769C
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Abstract
the invention discloses a rolling-cooling control steel and manufacturing method of hydraulic power plant steel pipe in the low-carbon low-alloy steel preparing domain, which comprises the following parts: 0.03-0.10% C, 0.05-0.20% Si, 1.0-3.0% Mn, not more than 0.02% P, not more than 0.015% S, 0.3-2.0% Cr, 0.20-0.60% Ni, 0.05-0.15% Nb and 0.0006-0.003% B. the chemical component of steel satisfies the following relational expressions: (1): 1.50%<=Cr+Mn<=3.5% (2): 1.5C<=Nb, wherein the opening temperature is not less than 1100 deg.c; the total pressure rate over 950 deg.c is over 50%. and is over 65% when lower than 950 deg.c; the terminal rolling temperature is controlled between 800 and 930 deg.c; the remaining time of rolling temperature is 50-500s, which can be cooled to indoor temperature at 2-18 deg.c per s.
Description
Technical field
The present invention relates to a kind of hydropower station pressure steel pipe with the cold steel of high strength control control, belong to low-carbon low-alloy steel and make the field.
Background technology
The technician of the technical field of the invention is fully aware of, and steel construction such as hydropower station pressure steel pipe, bifurcated pipe and spiral case belong to plate of moderate thickness with steel plate, and thickness range generally between 25-65mm, needs a large amount of welding procedures in the engineering construction process.China's hydropower station pressure steel for steel pipes is mostly used low welding crack sensitivity steel (abbreviating the CF steel as) manufacturing at present, adopts two kinds of technological processs to produce this steel, and a kind of is modified process; Another kind of is controlled rolling+tempering process.This CF steel contains the alloying elements such as Mo, V of higher level because of complex chemical composition, and production process is more, thereby cost an arm and a leg, in addition, though the tensile strength of modified CF steel reaches the 600MPa level, but its yield strength is higher with the ratio (abbreviating yield tensile ratio as) of tensile strength, generally be higher than 0.9, the steel yield tensile ratio that has even reach 0.95, shock resistance is low, poor stability, can not engineering demands, and, traditional CF steel drift hit toughness require be :-20 ℃ of A
Kv〉=47J.Along with steel construction such as hydropower station pressure steel pipe, bifurcated pipe and spiral case progressively develop to the maximization direction, requirement to the impact toughness of steel also improves gradually, impact toughness 〉=the 47J of traditional C F steel can not meet the demands, for large-scale hydraulic power pressure steel pipe, bifurcated pipe and spiral case-20 ℃ of A with steel
KvRequirement is higher than 54J or higher.Therefore, for reducing the production cost of hydropower station pressure steel for steel pipes, all making great efforts to develop various high strength, high tenacity, the relatively low steel grade of cost both at home and abroad.Steel penstock for improving welding efficiency and improving the site welding operating environment, extensively adopts some advanced welding technique in implementing construction in addition, for this reason, requires steel penstock can adapt to different welding condition with steel, has good welding property.Fast development along with Chinese national economy, steel construction such as hydropower station pressure steel pipe progressively develop to high strength, maximization direction, thus the development and production cost low have good combination of strength and toughness and have a hydropower station pressure steel pipe of excellent welding performance imperative with rolling controlled and cooling controlled steel.
Before the present invention proposes, Chinese patent Granted publication CN1084798C has introduced " high tenacity; the manufacture method of high wear resistant steel of slurry pipeline ", by smelting, forge, hot rolling, technological process production such as batch after the cooling, its chemical ingredients is by weight percentage: C:0.02-0.05, Mn:0.50-1.0, Si:0.15-0.45, Cr:0.50-0.80, Cu:0.15-0.40, Ni:0.10-0.25, Mo:0.15-0.30, Nb:0.02-0.05, Ca:0.0010-0.0080, N:0.0070-0.03, Ti:0.01-0.022, S≤0.0060, coiling temperature is 540 ± 20 ℃.That utilizes solid solution nitrogen and nitride separates out the acquisition certain intensity.Its weak point is, the chemical ingredients more complicated, and contain expensive Alloy Elements Mo, improved manufacturing cost.In addition, the welding scope that this steel can adapt to is less, can not bear advanced weldprocedures such as large-line energy welding, thereby can not be used for the construction of hydropower station pressure steel pipe, bifurcated pipe and spiral case.
Another Chinese patent Granted publication CN1040555C discloses " fatigue strength of weld and the high-strength steel of excellent weldability and manufacture method thereof ".Its chemical ingredients is by weight percentage: C:0.03-0.20%, Si:0.6-2.0%, Mn:0.6-2.0%, Al:0.01-0.08%, below the B:0.002%, and below the N:0.002-0.008%, also can add alloying elements such as Cu, Mo, Ni, Cr, Nb, V, Ti, Ca and REM, adopt common rolling or controlled rolling method manufacturing.Deficiency is: one, and the complex chemical composition of steel, production process is restive, makes product percent of pass reduce, and has increased cost; Its two, contain expensive Alloy Elements Mo, V etc., be not a kind of economic shaped steel; Its three, because of containing strong oxidizing property alloying elements such as alloy element Al, REM, the stifled easily casting of the oxide compound that casting cycle the forms mouth of a river produces dangerous.A Chinese patent Granted publication CN1083893C discloses " high-tensile-strength steel and production method thereof " again, tensile strength is higher than 900MPa, its chemical ingredients is by weight percentage: C:0.02-0.1%, Si≤0.6%, Mn:0.2-2.5%, Ni:0.2-1.2%, Nb:0.01-0.1%, Ti:0.005-0.03%, Al≤0.1%, N:0.001-0.006%, Cu:0-0.6%, Cr:0-0.8%, Mo:0-0.6%, V:0-0.1%, B:0-0.0025%, Ca:0-0.006%, P≤0.015%, S≤0.003%.Deficiency is that the chemical ingredients of steel is very complicated, causes the production process complexity.Require the S content of steel not to be higher than 0.003%, increased the production difficulty, improved production cost.
Summary of the invention
For overcoming the deficiency of above-mentioned background technology and existing hydropower station pressure steel for steel pipes, the object of the present invention is to provide a kind of economical hydropower station pressure steel pipe to have the rolling controlled and cooling controlled steel and the production method thereof of excellent welding performance with high strength (yield strength is greater than 490MPa), the problem that emphasis solves is: 1. reduce the yield tensile ratio of steel, the yield tensile ratio that makes steel is less than 0.8; 2. further improve the low-temperature impact toughness of steel, make the impact toughness-20 ℃ A of steel
Kv〉=54J.Steel plate according to production method manufacturing of the present invention integrates high strength, high tenacity and low cost, adapts to the welding scope of broad.Production process is controlled easily, and is simple to operate, and production cost is lower, is fit to scale production.
The present invention in order to achieve the above object, designed a kind of hydropower station pressure steel pipe high strength rolling controlled and cooling controlled steel, its chemical ingredients is by weight percentage: C:0.03-0.10%, Si:0.05-0.20%, Mn:1.0-3.0%, P≤0.02%, S≤0.015%, Cr:0.3-2.0%, Ni:0.20-0.60%, Nb:0.05-0.15%, B:0.0006-0.003%.The chemical ingredients of this steel satisfies following relational expression:
(1)：1.50％≤Cr+Mn≤3.5％； (2)：1.5C≤Nb。
The chemical ingredients of the present invention in above-mentioned scope is by weight percentage: C:0.03-0.065%, Si:0.05-0.10%, Mn:2.0-2.60%, P:0.010, S:0.006%, Cr:0.80-1.2%, Ni:0.30-0.35%, Nb:0.065-0.10%, B:0.0008-0.0015%.
The further chemical ingredients of the present invention is by weight percentage: C:0.065%, Si:0.07%, Mn:2.25%, P:0.012%, S:0.009%, Cr:1.15%, Ni:0.40%, Nb:0.10%, B:0.0012%.
The present invention is by above-mentioned preferred chemical ingredients, it manufactures the hydropower station pressure steel pipe is pricked the cold steel of control with control method, be to adopt start rolling temperature 〉=1100 ℃, rolling total draft 〉=50% more than 950 ℃, rolling total draft 〉=65% below 950 ℃, finishing temperature is controlled at 800-930 ℃ of temperature range, and at the finishing temperature residence time: 50-500s, the cooling rate with 2-18 ℃/s is chilled to room temperature then after the finish to gauge.Yield strength 〉=the 490MPa of steel, tensile strength: 610-750MPa, yield strength with the control cold strength ratio less than 0.80, impact toughness :-20 ℃ of A
Kv〉=54J, and have excellent welding property.
The setting of main alloy element content of the present invention and manufacture method are according to following principle.
1. the low high Mn alloying of C mode is also passed through to add an amount of alloying elements cr, makes steel transformation temperature reduction in the continuous cooling process after distortion, suppresses the ferritic formation of the non-shaping of original austenite crystal prevention, impels acicular ferrite to form at intracrystalline.In the low temperature phase change temperature province, suppress grain growth speed in the phase transition process, increase nucleation rate, thus crystal grain thinning.
2. high Nb alloying steel of the present invention.Acting in conjunction by Nb atom drageffect and small and dispersed Nb (CN) precipitated phase, the recrystallization temperature of steel is brought up to more than 950 ℃, make rolling deformation to carry out and the crystal grain phenomenon (recrystallize) of growing up unusually can not occur and cause mixed crystal, the performance of reduction steel in the high-temperature zone wide temperature range.
3. by cooling controlling and rolling controlling process process of the present invention, suppress non-shaping ferrite in high-temperature zone and perlitic transformation, steel is fully changed at middle warm area and bainite (acicular ferrite) transformation range, form the acicular ferrite structure of some amount, the steel of production has high strength, high tenacity.Below further describe the reason of selecting each alloying element and composition range in the steel of the present invention.
C: be one of gap strengthening element effective, the most most economical in the steel, in order to improve the intensity of steel, as if as long as the carbon content in the increase steel, but excessive C content can make the welding property of steel and fracture toughness property significantly reduce, on the contrary, if C content is low excessively, then be difficult to ensure the intensity of steel, one of feature of the present invention is the low high Mn alloying of C, through intensity, welding property and the fracture toughness property of overall equilbrium steel, the span of C content is defined as: 0.03-0.10%.
Si: the displacement solution strengthening element that is a kind of economy, china natural resources is very abundant, add the intensity that can significantly improve steel in the steel, and the welding property to steel does not have tangible negative impact, if but add Si too much, and can make the toughness of steel, low-temperature flexibility is obviously reduced, satisfying under the prerequisite of intensity, should reduce the content of Si as far as possible.The intensity of comprehensive steel and the consideration of toughness two aspects are defined as the composition range of Si: 0.05-0.20%.
Mn: not only can increase the intensity of steel, can also reduce the transformation temperature of steel, by the controlled rolling process, crystal grain thinning, improve its fracture toughness property simultaneously in the intensity that improves steel, low-alloy high-strength steel develops towards the high Mn direction of low C, so the scope of Mn content is set at: 1.0-3.0%.Contain proper C r in the steel, can improve the hardening capacity of steel, suppressing the high temperature transformation of steel in continuous cooling process is perlite, ferritic transformation, and impelling middle temperature transformation is that bainite (acicular ferrite) changes, and makes steel have good combination of strength and toughness.Ni, Cr can improve the hardening capacity and the corrosion resistance of steel, Ni can significantly improve the low-temperature flexibility of steel mother metal and welding joint, but Ni belongs to noble metal, China Ni scarcity of resources should not be added in the structure iron, though Cr can improve the corrosion resistance nature of steel, but too much Cr content is unfavorable to the welding property of steel, reduce the toughness of steel, comprehensively weigh the pros and cons of each alloying element, Ni and Cr content range are set at 0.20-0.60% and 1.0-2.0% respectively.
The Nb that adds trace in the steel, main purpose is to improve the recrystallization temperature of steel, make rolling can finishing at comparatively high temps, reduce the rolling drag of rolling mill equipment, increase the service life, the Nb of trace also has crystal grain thinning and improves intensity and flexible effect, the relation of Nb and C content is defined as: 1.5C≤Nb, be because Nb moves in the austenite grain boundary that solid solution condition and Nb (CN) precipitated phase all can suppress steel, improve the recrystallization temperature of steel more than 950 ℃.Part Nb separates out in conjunction with forming Nb (CN) mutually with C, tiny precipitated phase also can stop the recrystallize of steel, remainder Nb is dissolved in the recrystallize that suppresses steel in the steel by the atom effect of dragging admittedly, free C content significantly reduces in the matrix of steel after this handles, be unlikely in subsequent cooling process, to form perlite, worsen the performance of steel.Therefore Nb content is defined as 0.05%≤Nb≤0.15%, and 1.5C≤Nb.
B is the intensive element of hardening capacity that improves steel, the B that adds trace, with alloying element combined action such as Mn, Cr, the high temperature transformation that suppresses steel, the warm area acicular ferrite changes in impelling, and make steel have the favorable mechanical performance, but too high B content easily causes boron crisp, reduce the toughness of steel, so the B content of steel is limited to 0.0005-0.003%.
P, S are deleterious impurity elements in the steel, reduce the toughness and the welding property of steel, content is low more good more, but if limit its content low excessively, can increase the production difficulty, improve production cost, therefore under the prerequisite that does not influence toughness and welding property, steel is got P, S content be each defined in≤0.02% and≤0.015% normal ranges.
The principle of production method of the present invention institute foundation.
Start rolling temperature is set at is higher than 1100 ℃,,, have some and second precipitate mutually and separate out, in the operation of rolling, crack, cause waste product if start rolling temperature was set low generally 1100～1190 ℃ of beginning roughing.On the other hand, reduce if start rolling temperature is crossed the low final rolling temperature that will cause, low excessively finishing temperature can cause the rolling equipment wastage rate to increase.In the actual production, limit, generally the strand temperature can be heated to above 1300 ℃, therefore as long as set the start rolling temperature lower limit by save energy and equipment heating efficiency.
Owing to added an amount of alloy element Nb, the non-recrystallization temperature of steel is brought up to 950 ℃, rolling for roughing more than 950 ℃, rolling for finish rolling below 950 ℃, the roughing process is that recrystallize is rolling, draft requires to be higher than 50% purpose and is broken thick crystal grain, eliminate as-cast structure, make uniform crystal particles, peel off dirt settlings such as billet surface oxide skin, for finish rolling is prepared.The finish rolling draft requires to be higher than 65%, and purpose is by heavy reduction, as far as possible crystal grain thinning, finishing temperature is controlled at 800-930 ℃ of temperature range, at the finishing temperature residence time: 50-500s, purpose is to form the tiny precipitated phase that disperse distributes, the intensity of raising steel of being of particle after the finish to gauge.Finish to gauge and insulation back are chilled to room temperature with the cooling rate of 2-18 ℃/s, can form acicular ferrite structure in this cooling rate scope, not only have good intensity, also have good toughness and welding property.
Composition requirement according to steel of the present invention, smelted existing patent comparative steel before the 6 batches of steel of the present invention and the 4 crowdes of the application, carry out mechanical property and oblique Y type groove constraint welding test, the results are shown in Table 1, when carrying out welding test, not preheating before the weldering, the welding surroundings temperature is 26 ℃, relative humidity is 95%, and postwelding is thermal treatment not.By table 1 as seen, steel of the present invention not only reaches requirement of strength, and has good low-temperature impact toughness, and welding joint is not all found crackle, show that steel of the present invention has good welding property, and 4 batches of comparative steel yield strengths all do not reach 490MPa, and yield tensile ratio all is higher than 0.81.No. 13 and No. 14 steel are because of containing excessive N in the comparative steel, and tiltedly Y type groove constraint welding joint is all found crackle.
The mechanical property of table 1 steel of the present invention and comparative steel and oblique Y type groove The experiment results
Steel of the present invention also has following advantage:
1) chemical ingredients is simple relatively, and production process is operated easily, and production cost is low, production efficiency height, suitable scale production.
2) not only have high strength (yield strength is greater than 490MPa), and have good welding property, adopt various welding technique welding steel of the present invention, all can not produce welding crack, significantly improve construction quality.
3) the present invention replaces expensive Alloy Elements Mo, V etc. with the associating alloying of cheap alloying element Mn, Cr and Nb, and can suitably reduce the content of Ni in the steel, and the cost of steel is significantly reduced.Adopt cooling controlling and rolling controlling process to replace traditional modified and controlled rolling+tempering process in addition, shortened the production cycle, increased output, alleviated labour intensity and further reduced production cost, economic benefit and obvious social benefit.
Embodiment
The chemical ingredients of screening has been carried out the smelting of 4 batches of steel according to the present invention, and concrete chemical ingredients is by following embodiment 1-4.
Embodiment 1
The invention process steel chemical composition (weight percent)
C：0.04，Si：0.09，Mn：2.25，P：0.011，S：0.010，B：0.001，Ni：0.30，Cr：1.10，Nb：0.065。
Embodiment 2
The invention process steel chemical composition (weight percent)
C：0.05，Si：0.06，Mn：2.10，P：0.012，S：0.006，B：0.0011，Ni：0.40，Cr：0.90，Nb：0.08。
Embodiment 3
The invention process steel chemical composition (weight percent)
C：0.065，Si：0.07，Mn：2.0，P：0.010，S：0.009，B：0.0012，Ni：0.25，Cr：0.80，Nb：0.10。
Embodiment 4
The invention process steel chemical composition (weight percent)
C：0.03，Si：0.085，Mn：2.30，P：0.013，S：0.005，B：0.00135，Ni：0.55，Cr：1.15，Nb：0.055。
Production method condition of the present invention is rolled into the thick steel plate of 20mm, start rolling temperature 〉=1100 ℃, 950 ℃, more than rolling total draft 〉=50%, 950 ℃, below rolling total draft 〉=65%, finishing temperature is: 810-860 ℃, after the finish to gauge in the finishing temperature residence time be: 100-200s, finish to gauge insulation back is chilled to room temperature with the cooling rate of 5-10 ℃/s.
Carry out mechanical property from the sampling of embodiment finished product steel plate and detect, steel grade of the present invention all reaches requirement through the performance index such as armor plate strength, impact toughness and yield tensile ratio of above-mentioned process for making production.
Claims (4)
1. hydropower station pressure steel pipe rolling controlled and cooling controlled steel, the chemical ingredients that it is characterized in that this steel is by weight percentage: C:0.03-0.10%, Si:0.05-0.20%, Mn:1.0-3.0%, P≤0.02%, S≤0.015%, Cr:0.3-2.0%, Ni:0.20-0.60%, Nb:0.05-0.15%, B:0.0006-0.003%, the chemical ingredients of this steel satisfies following relational expression:
(1)：1.50％≤Cr+Mn≤3.5％；(2)：1.5C≤Nb。
2. by the described a kind of hydropower station pressure steel pipe rolling controlled and cooling controlled steel of claim 1, it is characterized in that this steel chemical composition is by weight percentage: C:0.03-0.065%, Si:0.05-0.10%, Mn:2.0-2.60%, P:0.010%, S:0.006%, Cr:0.80-1.2%, Ni:0.30-0.35%, Nb:0.065-0.10%, B:0.0008-0.0015%.
3. by the described a kind of hydropower station pressure steel pipe rolling controlled and cooling controlled steel of claim 1, it is characterized in that this steel chemical composition is by weight percentage: C:0.065%, Si:0.07%, Mn:2.25%, P:0.012%, S:0.009%, Cr:1.15%, Ni:0.40%, Nb:0.10%, B:0.0012%.
4. produce a kind of method of producing the hydropower station pressure steel pipe as claimed in claim 1 with rolling controlled and cooling controlled steel, it is characterized in that adopting start rolling temperature 〉=1100 ℃, rolling total draft 〉=50% more than 950 ℃, rolling total draft 〉=65% below 950 ℃, finishing temperature is controlled at 800-930 ℃ of temperature range, at the finishing temperature residence time: 50-500s, the cooling rate with 2-18 ℃/s is chilled to room temperature then after the finish to gauge.
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| CNB2006100200380A CN100420769C (en) | 2006-08-24 | 2006-08-24 | Rolling controlled and cooling controlled steel for hydraulic power station penstock and manufacture method thereof |
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| CNB2006100200380A CN100420769C (en) | 2006-08-24 | 2006-08-24 | Rolling controlled and cooling controlled steel for hydraulic power station penstock and manufacture method thereof |
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| CN100420769C true CN100420769C (en) | 2008-09-24 |
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| CN103045965A (en) * | 2012-12-27 | 2013-04-17 | 内蒙古包钢钢联股份有限公司 | Technique for manufacturing steel plate for 600MPa hydropower steel penstock |
| CN106636896A (en) * | 2016-12-05 | 2017-05-10 | 武汉钢铁股份有限公司 | High hardenability hot-rolled knife board steel |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1236020A (en) * | 1999-05-31 | 1999-11-24 | 宝山钢铁(集团)公司 | Method for producing high toughness, high wear resistant steel of slurry pipeline |
| CN1715435A (en) * | 2004-06-30 | 2006-01-04 | 宝山钢铁股份有限公司 | Method for producing X80 pipeline steel having anti-HIC property and its hot-rolled plate |
| CN1760398A (en) * | 2005-07-26 | 2006-04-19 | 武汉钢铁(集团)公司 | Steel in use for soldering pressure pipe in hydraulic power station under large line energy, and manufacturing method |
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2006
- 2006-08-24 CN CNB2006100200380A patent/CN100420769C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1236020A (en) * | 1999-05-31 | 1999-11-24 | 宝山钢铁(集团)公司 | Method for producing high toughness, high wear resistant steel of slurry pipeline |
| CN1715435A (en) * | 2004-06-30 | 2006-01-04 | 宝山钢铁股份有限公司 | Method for producing X80 pipeline steel having anti-HIC property and its hot-rolled plate |
| CN1760398A (en) * | 2005-07-26 | 2006-04-19 | 武汉钢铁(集团)公司 | Steel in use for soldering pressure pipe in hydraulic power station under large line energy, and manufacturing method |
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