CN105463324B - A kind of thick-specification high-tenacity pipe line steel and its manufacture method - Google Patents

A kind of thick-specification high-tenacity pipe line steel and its manufacture method Download PDF

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CN105463324B
CN105463324B CN201610025495.2A CN201610025495A CN105463324B CN 105463324 B CN105463324 B CN 105463324B CN 201610025495 A CN201610025495 A CN 201610025495A CN 105463324 B CN105463324 B CN 105463324B
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steel
thick
pipe line
line steel
thickness
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CN201610025495.2A
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CN105463324A (en
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章传国
郑磊
孙磊磊
柏明卓
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宝山钢铁股份有限公司
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226Hot rolling
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C33/00Making ferrous alloys
    • C22C33/04Making ferrous alloys by melting
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/002Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/14Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium

Abstract

A kind of thick-specification high-tenacity pipe line steel and its manufacture method, the chemical composition mass percent of the steel is:C:0.015~0.085%, Si:0.1~0.5%, Mn:0.4~1.5%, P≤0.015%, S≤0.003%, Cr:0.1~0.4%, Mo:0.04~0.09%, Nb:0.01~0.06%, Ti:0.005~0.02%, Ca:0.001~0.005%, Al:0.02~0.045%, 0.04%≤Nb+C≤0.1%, remaining is Fe and inevitable impurity.The present invention uses the component system of low C microalloyings, with reference to the big pressure of low-temperature heat, roughing and control the manufacturing process such as cold, the 450Mpa of 25~40mm think gauges and the pipe line steel of above grade of steel are obtained, and the pipe line steel has good low-temperature flexibility, the long distance delivery available for natural gas.

Description

A kind of thick-specification high-tenacity pipe line steel and its manufacture method
Technical field
The present invention relates to pipe line steel, and in particular to a kind of thick-specification high-tenacity pipe line steel and its manufacture method.
Background technology
Think gauge line pipe is mainly used in big throughput pipeline, submerged pipeline, passes through the specific demands such as earthquake zone pipeline and evil Bad environmental area.The development exploited with petroleum resources and polar region is moved towards by inland, ocean moved towards by land, deep-sea is moved towards by shallow sea And the growth requirement of the big throughput rate of pipeline, thick-walled pipe spool will be widely used in oil-gas pipeline construction, should with good Use prospect.It is thus right to improve the security of submarine pipeline operation, reduction maintenance cost, it is necessary to using heavy wall high tenacity welded tube Steel for pipe proposes think gauge, the demand of high tenacity;It is riser tubing conveying capacity for terrestrial pipeline, is keeping Need to use heavy caliber thick wall welded tube in the case that grade of steel is constant, high intensity, the need of think gauge are thus proposed to steel for pipe Ask.Therefore, think gauge pipe line steel is by the major products as future application, and its difficult point developed essentially consists in how to ensure full wall Thick intensity and low-temperature flexibility, especially DWTT (Drop weight tear test, drop weight tearing test) performance.
Prior art key is the performance of specification pipe line steel after being realized by equipment capability lifting, and such as Di Lingen is by adopting More than the 400mm thick continuous casting billet of spy is manufactured with vertical casting machine, thus for think gauge Pipeline Steel Plate manufacture established high endoplasm, The basis of big pressure ratio, and provide sheet stock to enterprises such as European steel pipe, VSK.Japanese JFE companies use burning optimization on line Device, using the structural homogenity on HOP process improving steel plate thickness direction, is conducive to improving the DWTT of think gauge pipe line steel Uniform mechanical property and can be obtained, while the ovality of steel pipe can also be improved.
Chinese many enterprises have carried out the developmental research of think gauge pipe line steel, and main direction of studying has:Duplex structure's ratio Example is studied the affecting laws of DWTT performances, shows tough with optimal increase pipe line steel when ratio of ferrite is about 28% The effect of property;By increasing the single pass reduction ratio of roughing passage come refinement microstructure, so as to improve think gauge pipe line steel Low-temperature flexibility.
European patent EP 2105513B1 discloses a kind of manufacture method of Welding Thick Pipe Pipeline Steel Plate, micro- using low-carbon Alloying component system, and volume fraction by controlling bainite is more than 80%, can manufacture strength grade 600MPa with Upper, thickness is the Pipeline Steel Plate of 20~40mm specifications.The patent is to employ the elements such as Zr, B, refines the crystallite dimension of steel and carries Gao Gang quenching degree, to control the crystallite dimension of heat affected area, improves impact flexibility.
Japan Patent JP55008454A discloses a kind of manufacture method of V-type steel, is closed using C-Mn basic ingredients and vanadium are micro- The composition design of aurification, by controlling total deformation >=30% of Ar3~900 DEG C, Ar3~Ar1 deflections to be 10~60%, so Air cooling or the rolling mill practice batched, realize the crystal grain refinement of steel afterwards, and improve obdurability.
Japan Patent JP58055529A discloses a kind of manufacture method of think gauge hot rolling pipeline steel strip, using low C alloy The composition design of change, by controlling low heating-up temperature and coexistence region rolling reduction >=30%, then with more than or equal to 3 DEG C/s's Cooling rate is cooled to 480 DEG C and batched, and can manufacture hot-rolled sheet coil more than the 4.5mm specifications with high intensity.
The content of the invention
It is an object of the invention to provide a kind of thick-specification high-tenacity pipe line steel and its manufacture method, the pipe line steel is advised to be thick Lattice high tenacity 450MPa and above Grade Pipeline Steel, finished steel plate thickness is 25~40mm, and the microscopic structure of the steel is to refine Based on polygonal ferrite, its yield strength >=450MPa, tensile strength >=535MPa, -20 DEG C of full-scale Charpy-V impact powers >= 250J, -20 DEG C of full thickness of slab DWTT Percentage of Shear Fracture For Fracture Surface percentage >=85%, while having manufacturability, may be utilized in fabricating heavy wall Straight-line joint submerged arc welding tube, applied to submarine pipeline, crossing pipeline and polar region pipe-line construction etc., is mainly used in the long range of natural gas Conveying.
To reach above-mentioned purpose, technical scheme is as follows:
A kind of thick-specification high-tenacity pipe line steel, its chemical composition mass percent is:C:0.015~0.085%, Si:0.1 ~0.5%, Mn:0.4~1.5%, P≤0.015%, S≤0.003%, Cr:0.1~0.4%, Mo:0.04~0.09%, Nb: 0.01~0.06%, Ti:0.005~0.02%, Ca:0.001~0.005%, Al:0.02~0.045%, remaining be Fe and Inevitable impurity, and above-mentioned element need to meet following relation simultaneously:0.04%≤Nb+C≤0.1%.
Further, the chemical composition also includes:Cu≤0.4%, Ni≤0.4%, N≤0.01%, B≤0.0004%, O ≤ 0.005%, V≤at least one of 0.08%, it is calculated in mass percent.
The microstructure of thick-specification high-tenacity pipe line steel of the present invention based on the polygonal ferrite that refines, wherein, Volume ratio shared by polygonal ferrite is 40~90%, polygonal ferrite crystallite dimension≤10 μm.
Yield strength >=450MPa of thick-specification high-tenacity pipe line steel of the present invention, tensile strength >=535MPa, -20 DEG C Full-scale Charpy-V impact power >=250J, -20 DEG C of full thickness of slab DWTT Percentage of Shear Fracture For Fracture Surface percentage >=85%.
In the Design of Chemical Composition of the present invention:
C:C is most basic intensified element, and C, which is dissolved in steel, forms interstitial solid solution, plays solution strengthening, and strong Carbide former formation Carbide Precipitation, then play a part of precipitation strength.But too high C is to the toughness and weldability of steel Can be unfavorable;C is too low and reduces the intensity of steel.Therefore, the present invention controls C content to be 0.015~0.085%.
Si:Si is solution strengthening element, while be also the deoxidant element in steel, but too high levels can deteriorate the welding of steel Performance, is removed while being unfavorable for hot rolling iron scale in the operation of rolling, therefore, and present invention control Si contents are 0.1~0.5%.
Mn:Mn improves the intensity of steel by solution strengthening, is to compensate in steel to cause loss of strength most because C content is reduced Mainly, economic intensified element.Mn still expands the element of γ phase regions, it is possible to decrease γ → α phase transition temperatures of steel, helps to obtain Tiny phase-change product, can improve the toughness of steel;But Mn is easy segregation element, when Mn contents are higher, the Mn in casting cycle The martensitic structure of hard phase is easily generated after the completion of thickness of slab center segregation, rolling, the low-temperature flexibility and anti-dynamic for reducing material are torn Fragility energy.Therefore, the present invention controls Mn contents to be 0.4~1.5%.
Cr:Cr is the important element for the quenching degree for improving steel, it is ensured that the tissue and performance of thick steel plates through thickness are uniform Property, and Cr contents more than 0.10% when, can effectively improve the decay resistance of steel;But too high chromium and manganese add steel simultaneously In, low melting point Cr-Mn composite oxides can be caused to be formed, face crack is formed in hot procedure, while can severe exacerbation Welding performance.Therefore, Cr contents are limited to 0.1~0.4% in the present invention.
Mo:Mo is the element for expanding γ phase regions, it is possible to decrease γ → α phase transition temperatures of steel, can obtain more tiny phase Become tissue, improve the toughness of steel;Simultaneously a small amount of Mo can improve the quenching degree of steel, improve the structural homogenity of thickness direction.But With the rising of Mo contents, the ratio increase of low temperature phase change product, the low-temperature flexibility to steel is unfavorable, and damages the plasticity of steel.Therefore, The control of Mo contents is 0.04~0.09% in the present invention.
Cu、Ni:The intensity of steel can be improved by solution strengthening effect, while Cu can also improve the corrosion resistance of steel, Ni's adds Enter to improve Cu easily caused red brittleness in steel, while the low stacking fault energy of sliding can drop, and it is beneficial to toughness.Therefore, this hair Bright middle Cu, Ni content control range is≤0.4%.
Nb:Nb is that the Nb strain induced precipitates of solid solution in one of important element of low-carbon micro steel-alloy, course of hot rolling are formed Nb (N, C) particle, pinning crystal boundary suppresses the generation grown up and suppress recrystallization of deformed austeaite, cold through controlled rolling and control But deformed austeaite is made mutually to be changed into the tiny product with high dislocation density.The Nb of solid solution is after batching, with second phase particles NbC disperse educts in matrix, play precipitation strength effect.For think gauge pipe line steel, too low Nb contents disperse analysis Go out DeGrain, do not have crystal grain thinning, reinforcing matrix effect;Too high Nb contents, due to inhibiting steel plate core to tie again Brilliant generation, is unfavorable for crystal grain refinement.And Nb solid solution is relevant with C content, the too high Nb solid solution capacities of C content are few, it is impossible to play analysis Go out reinforcing and crystal grain downslide effect;C content is too low to cause grain-boundary weakness, and the too low then precipitating reinforcing effect of Nb contents is not obvious. Therefore, Nb contents should be limited to 0.01~0.06% in the present invention, and require 0.04%≤Nb+C≤0.1%.
Ti:Ti is a kind of strong carbonitride-forming elements, and Ti not molten carbonitride can hinder when steel is heated Only austenite crystal is grown up, and the TiN separated out in high temperature austenite area during roughing can effectively suppress Austenite Grain Growth.In addition In welding process, the TiN particles in steel can significantly prevent heat affected area crystal grain from growing up, so that the welding performance for improving steel plate is same When to improve welding heat affected zone impact flexibility have obvious effect.Therefore, in the present invention control of Ti contents 0.005~ 0.02%.
V:V is important micro alloying element, and the intensity of steel is mainly improved by middle low temperature precipitation strength effect, but V contains When amount is too high, precipitation is particle coarsening substantially to damage the low-temperature flexibility of steel, therefore, present invention control V content≤0.08%.
N:In micro alloyed steel, appropriate nitrogen content can play suppression and add again by forming dystectic TiN particles The effect of slab grain coarsening in thermal process, improves the obdurability of steel.But when N content is too high, the free N of high concentration after timeliness Atom pinning dislocation, significantly improves yield strength, while damaging toughness.Therefore, N≤0.01% is controlled in the present invention.
O:For the pure steel smelting of low-alloy, it is required to carry out deoxidation treatment in smelting endpoint, to reduce in casting cycle The bubble and oxide of generation are mingled with, and improve the endoplasm of steel, improve the low-temperature impact toughness and anti-dynamic tear of finished steel plate Performance.When oxygen content is higher than 50ppm, the endoplasm defect such as field trash, stomata significantly increases.Therefore, the present invention in control O≤ 0.005%.
S、P:S, P are inevitable impurity elements in steel, it is desirable to more low better.By super-low sulfur (be less than 30ppm) and Ca processing carries out inclusion morphology control to sulfide, while controlling P content below 0.015%, it is ensured that invention steel has good Good low-temperature impact toughness.
Ca:The form of sulfide can be controlled by Ca processing, improves the anisotropy of steel plate, low-temperature flexibility is improved, is The control range for ensuring optimum efficiency Ca is 0.0010~0.0050%.
Al:Al is the element added for deoxidation in steel, adds appropriate Al and is conducive to crystal grain thinning, improves steel Al content control range is 0.02~0.045% in toughness and tenacity, the present invention.
B:B is strong quenching degree element, and easily separates out the plasticity for causing material, toughness decline, therefore, present invention control in crystal boundary B≤0.0004% processed.
The manufacture method of thick-specification high-tenacity pipe line steel of the present invention, it comprises the following steps:
1) smelt, cast
Smelted according to above-mentioned chemical composition, be casting continuously to form slab, slab thickness t >=11T, T is finished steel plate thickness;
2) heat
Heating-up temperature is 960~1090 DEG C, and soaking time is (0.8~1.50) t minutes, and t is slab thickness, unit mm;
3) roll
Roughing finishing temperature is 920~1000 DEG C, roughing single pass reduction ratio >=9%, and workpiece thickness is finished steel plate 4~6 times of thickness;Finish rolling start rolling temperature is 750~810 DEG C, and finish rolling finishing temperature is 740~800 DEG C;
4) control cooling
Water cooling, cooling velocity is 20~60 DEG C/s, stops cold temperature for 300~550 DEG C;Water cooling is stopped cold rear natural air cooling and obtained Finished steel plate, finished steel plate thickness T is 25~40mm.
In the manufacturing process of the present invention:
The present invention sets heating-up temperature as 960~1100 DEG C, herein in relatively low heating temperature range, is conducive to suppressing former The roughening of beginning austenite crystal, is that follow-up crystal grain refinement lays the foundation.
Step 3) in, by controlling roughing finishing temperature to avoid producing the uneven mixed grain structure of size for 920~1000 DEG C; And the roughing single pass reduction ratio of 9% and the above is designed, it may advantageously facilitate the generation of thickness of slab core austenite recrystallization;Pass through control Middle base thickness is made for 4~6 times of finished steel plate thickness to ensure that non-recrystallization zone rolling deformation ratio reaches 4~6 times, promotes to tie again Flattening deformation fully occurs for brilliant austenite, to increase defect concentration and forming core point, promotes ferrite transformation and refines phase-change organization. Because the thickness of slab of the present invention is thicker, the temperature drop of finish rolling open rolling to finish to gauge is smaller, and 740~800 DEG C of above-mentioned finishing temperature and austenite- Ferritic phase temperature is approached, and finish to gauge may advantageously facilitate alpha ferrite phase transformation in this temperature range.
Step 4) in, cooling velocity is 20~60 DEG C/s:Cooldown rate >=20 DEG C/s is conducive to suppressing pearlitic transformation, cold But speed≤60 DEG C/s can avoid the excessive bainite of generation or production martensitic structure.
It is main using low-temperature heat, the big soft reduction process of roughing in design and manufacture technology of the present invention, and cooling is controlled, pass through control The grain size of original austenite processed refines final phase transformation crystallite dimension, obtains the refinement of thick steel plates total cross-section uniform Crystallite dimension, so as to improve the obdurability of steel;While opening present invention is mainly applied to the Pipeline Steel Plate of 25~40mm think gauges Hair.
Also there is following innovation in the present invention:
(1) designed using relatively low Nb alloys, reduction Nb suppresses the effect of recrystallization, promotes thick steel plates core fully to send out Raw dynamic recrystallization, while reaching the effect of crystal grain refinement and precipitation strength.
(2) by using low-temperature heat technique, suppress to reheat Austenite Grain Growth, it is big from Sources controlling crystallite dimension It is small, be conducive to follow-up crystal grain refinement.
(3) using refinement polygonal ferrite based on microscopic structure design, effective average grain size 10 μm with Under, crack growth resistance is lifted by using high density high-angle boundary, so as to effectively lift the anti-dynamic tear performance of steel.
Beneficial effects of the present invention:
The present invention with crystal grain refinement, is separated out by force for the 450MPa of 25~40mm think gauges and the pipe line steel of above grade of steel Based on the materials theories such as change, phase transformation control, the component system of low C microalloyings is employed, is specifically:Contained using relatively low C Amount, in low Mn, appropriate Nb, Ti microalloying and Cu, Ni, Cr, the composition design of a small amount of Mo alloyings;And combine controlled rolling and The thermo-mechanical treatment process of cooling is controlled, the steel plate of TMCP states is obtained, full thickness of slab is obtained based on fining ferrite (≤10 μm) Microscopic structure to improve the low-temperature flexibility of steel, the Mechanical Characteristics with high intensity, high tenacity, especially total wall thickness DWTT Performance section of shear rate reaches more than 85%.
25~40mm think gauge pipelines structure of steel that the present invention is produced, performance reach claimed below:
1) microscopic structure:Polygonal ferrite volume ratio:40~90%;Polygonal ferrite grain size:≤10μm;
2) tensile property:Yield strength Rt0.5:≥450MPa;Tensile strength Rm:≥535MPa;
3) -20 DEG C of full-scale Charpy-V impact power AKv:≥250J;
4) -20 DEG C of full thickness of slab DWTT (Drop Weight Tear Test, drop weight tearing test) performance Percentage of Shear Fracture For Fracture Surface Rate SA:>=85%.
Brief description of the drawings
Fig. 1 is the representative microstructure of the position of 6 pipe line steel thickness of slab of the embodiment of the present invention 1/2.
Fig. 2 is the representative microstructure of the position of 6 pipe line steel thickness of slab of the embodiment of the present invention 1/4.
Embodiment
With reference to embodiment and accompanying drawing, the present invention will be further described.
Table 1 is the composition of steel of the embodiment of the present invention, and the fabrication process parameters of the steel of the embodiment of the present invention of table 2, the present invention of table 3 is real Apply the performance of a steel.
Fig. 1, Fig. 2 are the typical microstructures of steel of the present invention.As shown in figure 1, being ferrite+bainite group at thickness of slab 1/2 Knit, polygonal ferrite ratio is 60% or so, and average grain size is at 8 μm or so;As shown in Fig. 2 being similarly at thickness of slab 1/4 Ferrite+bainite structure, polygonal ferrite ratio is 75% or so, and average crystal grain eats size for 7 μm or so.It can be seen that, this Organization type, the grain size of the through thickness of invention steel plate are basically identical, and polygonal ferrite ratio is 40~90%, ferrite Crystallite dimension≤10 μm.
As shown in Table 3, the present invention can manufacture 25~40mm think gauge pipe line steels, and its tissue, performance reach claimed below:
1) microscopic structure
Polygonal ferrite ratio:40~90%;
Polygonal ferrite grain size:≤10μm;
2) tensile property
Yield strength Rt0.5:≥450MPa;
Tensile strength Rm:≥535MPa;
3) -20 DEG C of full-scale Charpy-V impact powers
AKv:≥250J;
Percentage of Shear Fracture For Fracture Surface rate SA% (Shear Area):>=90%;
4) -20 DEG C of full thickness of slab DWTT (Drop Weight Tear Test, drop weight tearing test) performances
Percentage of Shear Fracture For Fracture Surface rate SA%:>=85%.
It can be seen that, composition and manufacturing process designed according to this invention, obtained pipe line steel are all up target performance requirement, With good comprehensive mechanical property, and carbon equivalent is relatively low, is conducive to improving steel pipe forming welding and site girth welding welding performance. Other present component is simple, and process window is wider, with stronger manufacturability.

Claims (7)

1. a kind of thick-specification high-tenacity pipe line steel, its chemical composition mass percent is:C:0.015~0.085%, Si:0.1~ 0.5%, Mn:0.4~1.5%, P≤0.015%, S≤0.003%, Cr:0.1~0.4%, Mo:0.04~0.09%, Nb: 0.01~0.06%, Ti:0.005~0.02%, Ca:0.001~0.005%, Al:0.02~0.045%, remaining be Fe and Inevitable impurity, and above-mentioned element need to meet following relation simultaneously:0.04%≤Nb+C≤0.1%;The pipe line steel leads to Following method is crossed to obtain:Including:
1) smelt, cast
Smelted according to above-mentioned chemical composition, be casting continuously to form slab, slab thickness t >=11T, T is finished steel plate thickness;
2) heat
Heating-up temperature is 960~1090 DEG C, and soaking time is (0.8~1.50) t min, and t is slab thickness, unit mm;
3) roll
Roughing finishing temperature is 920~1000 DEG C, roughing single pass reduction ratio >=9%, and workpiece thickness is finished steel plate thickness T 4~6 times;Finish rolling start rolling temperature is 750~810 DEG C, and finish rolling finishing temperature is 740~800 DEG C;
4) control cooling
Water cooling, cooling velocity is 20~60 DEG C/s, stops cold temperature for 300~550 DEG C;Water cooling stops cold rear natural air cooling and obtains finished product Steel plate, finished steel plate thickness T is 25~40mm.
2. thick-specification high-tenacity pipe line steel according to claim 1, it is characterised in that the chemical composition also includes:Cu ≤ 0.4%, at least one of Ni≤0.4%, N≤0.01%, B≤0.0004%, O≤0.005%, V≤0.08%, with matter Measure percentage meter.
3. thick-specification high-tenacity pipe line steel according to claim 1 or 2, it is characterised in that the thick-specification high-tenacity pipe The microstructure of line steel based on the polygonal ferrite that refines, wherein, volume ratio shared by polygonal ferrite for 40~ 90%, polygonal ferrite crystallite dimension≤10 μm.
4. thick-specification high-tenacity pipe line steel according to claim 1 or 2, it is characterised in that the thick-specification high-tenacity pipe Yield strength >=450MPa of line steel, tensile strength >=535MPa, -20 DEG C of full-scale Charpy-V impact power >=250J, -20 DEG C of full plates Thick DWTT Percentage of Shear Fracture For Fracture Surface percentage >=85%.
5. the manufacture method of thick-specification high-tenacity pipe line steel as claimed in claim 1 or 2, it is characterised in that including following step Suddenly:
1) smelt, cast
Smelted according to the chemical composition described in claim 1 or 2, be casting continuously to form slab, slab thickness t >=11T, T is finished product Steel plate thickness;
2) heat
Heating-up temperature is 960~1090 DEG C, and soaking time is (0.8~1.50) t min, and t is slab thickness, unit mm;
3) roll
Roughing finishing temperature is 920~1000 DEG C, roughing single pass reduction ratio >=9%, and workpiece thickness is finished steel plate thickness T 4~6 times;Finish rolling start rolling temperature is 750~810 DEG C, and finish rolling finishing temperature is 740~800 DEG C;
4) control cooling
Water cooling, cooling velocity is 20~60 DEG C/s, stops cold temperature for 300~550 DEG C;Water cooling stops cold rear natural air cooling and obtains finished product Steel plate, finished steel plate thickness T is 25~40mm.
6. the manufacture method of thick-specification high-tenacity pipe line steel according to claim 5, it is characterised in that the think gauge is high The microstructure of toughness pipe line steel based on the polygonal ferrite that refines, wherein, the volume ratio shared by polygonal ferrite is 40~90%, polygonal ferrite crystallite dimension≤10 μm.
7. the manufacture method of the thick-specification high-tenacity pipe line steel according to claim 5 or 6, it is characterised in that the thick rule Yield strength >=450MPa of lattice high tenacity pipe line steel, tensile strength >=535MPa, -20 DEG C of full-scale Charpy-V impact powers >= 250J, -20 DEG C of full thickness of slab DWTT Percentage of Shear Fracture For Fracture Surface percentage >=85%.
CN201610025495.2A 2016-01-15 2016-01-15 A kind of thick-specification high-tenacity pipe line steel and its manufacture method CN105463324B (en)

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