CN109680135A - A kind of pipeline X80 hot-rolled coil and the production method of thickness >=22mm - Google Patents

A kind of pipeline X80 hot-rolled coil and the production method of thickness >=22mm Download PDF

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CN109680135A
CN109680135A CN201910124829.5A CN201910124829A CN109680135A CN 109680135 A CN109680135 A CN 109680135A CN 201910124829 A CN201910124829 A CN 201910124829A CN 109680135 A CN109680135 A CN 109680135A
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thickness
hot
pipeline
rolled coil
temperature
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CN109680135B (en
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徐锋
徐进桥
李利巍
邹航
崔雷
岳江波
张鹏武
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Wuhan Iron and Steel Co Ltd
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Wuhan Iron and Steel Co Ltd
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    • C21D—MODIFYING 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
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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    • C21D6/00—Heat treatment of ferrous alloys
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    • C21D6/00—Heat treatment of ferrous alloys
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    • C21—METALLURGY OF IRON
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    • C21D6/00—Heat treatment of ferrous alloys
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    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
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    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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  • Heat Treatment Of Steel (AREA)

Abstract

A kind of pipeline X80 hot-rolled coil of thickness >=22mm, chemical component and wt% are as follows: C:0.025 ~ 0.045%；Si:0.15~0.30%；Mn:1.70~1.85%；P≤0.001%；S≤0.0012%；Alt:0.015 ~ 0.045%；Nb:0.060 ~ 0.080%；Ti:0.008 ~ 0.020%；Cr:0.15 ~ 0.30%；Mo:0.10 ~ 0.25%；Ni:0.10~0.25%；The control of harmful element: N≤0.006%, As≤0.012%, Sb≤0.01%, Sn≤0.015%, Pb≤0.01%, Bi≤0.01%, Ca≤0.006%；Production method: slab is heated after routinely smelting and casting base；Roughing；Finish rolling；It is cooling；It batches；It is air-cooled to room temperature.The present invention is guaranteeing mechanical property: R under the precondition that existing conventional production lines are not required to transformationt0.5>=570MPa, Rm>=625MPa, YR≤0.91, A50Under >=28%, HV10≤260, steel plate thickness can be greater than 22mm, until 23mm, and -20 DEG C of KV2>=300J, -15 DEG C of DWTTSA >=95%.

Description

A kind of pipeline X80 hot-rolled coil and the production method of thickness >=22mm
Technical field
The present invention relates to a kind of pipeline X80 steel and production method, belong to the pipeline X80 hot rolling of thickness >=22mm a kind of Roll bending and production method.
Background technique
With the environmental problem that the development and coal burning bring of Re-search on Urbanization process become increasingly conspicuous, China is to natural The demand of the gas energy increases in formula is broken out.From one line of transfering natural gas from the west to the east, two wires to the new Guangdong Zhejiang line, Sino-Russian put into operation in recent years The natural gas pipeline projects such as eastern line can be seen that pipe line steel just towards Hi-grade steel, heavy caliber, big wall thickness and high pressure with steel feature Developer conveying direction, on the one hand can significantly improve the air input efficiency of single conduit engineering, and another party can cut operating costs. But with the increase of wall thickness, low-temperature flexibility, especially low temperature block hammer performance can sharply decline.Think in the art: when When the product thickness of pipe line steel reaches 18.4mm or more, the every increase 1mm of thickness, then the difficulty of drop weight tearing toughness will increase by 10 Times.Therefore the X80 of think gauge is developed, the technique of most critical is exactly to solve the problems, such as that low temperature drops hammer toughness.
In general, the backbone network of natural gas high pressure conveying mainly uses made of the X80 hot rolled heavy plate of 22mm or more Straight-line joint submerged arc welding tube, but Wide and Thick Slab production efficiency is low, manufacturing cost is higher.Although with newly-built 2250mm heat domestic in recent years Tandem rolling producing line goes into operation or completes the transformation that cooling and strength is batched to old producing line, has and produces 22mm using hot continuous rolling producing line The ability of the above X80, but it there are thickness of strand deficiency, roll-force is smaller, intermediate base thickness limit is limited etc. a series of asks Topic, causing the X80 of 22mm or more to develop, there are still many difficulties.
It is retrieved, has the document that China Patent Publication No. is 107177784 A of CN, disclose a kind of 22mm think gauge The milling method of X80 heavy-caliber pipeline steel: it requires workpiece thickness in 68mm, final reduction rate >=25%, finish rolling first Compression ratio >=3 times.But it is unable to reach in conventional producing line, because base thickness limit is in 58mm among conventional producing line；Extreme trace Reduction ratio >=25%, it is too high to producing line equipment Requirement, easily there is roll breakage accident, and this method is only applicable to 22mm hot-rolled coil Production, when thickness is further added by, such as larger than 22mm then will be unable to meet the requirements.
China Patent Publication No. is the document of 104726665 A of CN, discloses a kind of Hot-roller of X80 pipe line steel roll bending Skill.DWTT stability is poor when though it solving production thickness >=20mm X80 pipe line steel roll bending in the prior art asks Topic, but require workpiece thickness in 58~60mm, and finish rolling compression ratio >=62%, entry temperature at finishing≤920 DEG C.It is not only normal It is unable to reach the thickness of intermediate base in rule producing line, and entry temperature at finishing is caused rolling load excessive, bitten process due to too low It is unstable, it is serious to damage precision rolling equipment and piling of steel accident easily occurs, and find out that this method is also only full from example citing The production of sufficient 22mm or less X80, therefore work as finished product thickness and further increase, meet the requirement.
Summary of the invention
It is an object of the invention to overcome the shortcomings of the prior art, one kind is provided and is not required to existing conventional production lines Under the precondition of transformation, guaranteeing mechanical property: Rt0.5 >=570MPa, Rm>=625MPa, YR≤0.91, A50>=28%, Under HV10≤260, steel plate thickness can be greater than 22mm, until 23mm, and -20 DEG C of KV2>=300J, -15 DEG C of DWTTSA >=95% Pipeline X80 hot-rolled coil and production method.
Realize the measure of above-mentioned purpose:
A kind of pipeline X80 hot-rolled coil of thickness >=22mm, chemical component and weight percent content are as follows: C: 0.025~0.045%；Si:0.15~0.30%；Mn:1.70~1.85%；P≤0.001%；S≤0.0012%；Alt: 0.015~0.045%；Nb:0.060~0.080%；Ti:0.008~0.020%；Cr:0.15~0.30%；Mo:0.10~ 0.25%；Ni:0.10~0.25%；The control of harmful element: N≤0.006%, As≤0.012%, Sb≤0.01%, Sn≤ 0.015%, Pb≤0.01%, Bi≤0.01%, Ca≤0.006%, remaining is Fe and inevitable impurity；Metallographic structure Are as follows: acicular ferrite and 10% granular bainite for being no more than volume ratio content, grain size is at 13~14 grades.
Preferably: the weight percent content of Cr is 0.15~0.27%.
Further preferably: the weight percent content of Cr is 0.15~0.23%.
Preferably: the weight percent content of Mo is 0.11~0.22%.
Preferably: the weight percent content of Ni is 0.10~0.23%.
Further preferably: the weight percent content of Ni is 0.13~0.19%.
A kind of method of the pipeline of thickness >=22mm with X80 hot-rolled coil is produced, step:
1) after routinely being smelted and be cast into continuous casting billet, slab is heated, heating and temperature control at 1150~1200 DEG C, Time inside furnace is 200~240min；
2.) roughing is carried out, carries out reversible rolling using seven passage milling trains, and control roughing end temp 970~1010 DEG C, in which: roughing it is last fall first and the passage of falling third reduction ratio 20~21%, the reduction ratio of the second passage is 18 ~20%；And to be separated by 10s~30s between each passage of last three passage and just be rolled；Workpiece thickness after roughing Control is in 55~58mm；
3) finish rolling is carried out, is carried out using seven rack unit of F1~F7, is only passed through in F5 rack without rolling therebetween；Control Entry temperature at finishing is at 925~960 DEG C, and finish rolling overall compression ratio is not less than 60%, and in F6 and F7 rack finish rolling compression ratio Control is being not less than 8%；Exit temperature at finishing is controlled at 780~820 DEG C；
4) it is cooling to carry out rapid cooling, cooling velocity control is in 30~40 DEG C/s；
5) it is batched, oiler temperature control is at 300~350 DEG C；
6) it is air-cooled to room temperature.
Preferably: the slab heating temperature is at 1150~1175 DEG C.
Preferably: being separated by 14~26s between each passage of last three passage and just be rolled.
Preferably: the entry temperature at finishing is at 935~955 DEG C.
In the present invention the reasons why effect and control of each component and main technique:
C:0.025~0.045%, carbon are most economical most important intensified elements in steel, can greatly improve the intensity of steel, But steel billet cleanliness is improved to reduce the Central Carbon Segregation generated during casting blank solidification as far as possible to special think gauge pipe line steel, It is designed using the ingredient of Ultra-low carbon, carbon content is limited to 0.025~0.045%.If its content is lower than 0.025% coil of strip Intensity declines to a great extent, and needs largely to add the alloys such as Mo, Ni, Cr, Nb being made up, and if carbon content is higher than 0.045% easily The carbon enrichment for causing slab center portion causes low temperature drop weight tearing toughness to be difficult to reach technical conditions requirement.
Si:0.15~0.30%, this yuan are known as solution strengthening and deoxidation, and content can not play reinforcing lower than 0.15% and make With, but modeling, the toughness of pipe line steel can be deteriorated if being higher than 0.30%, especially for welding heat affected zone impact reduce it is aobvious It writes.
Higher economic alloy element manganese is added in Mn:1.70~1.85%, can make up the damage of intensity caused by low-carbon It loses, meanwhile, manganese can also refine crystal grain to a certain extent, improve the impact flexibility of steel, but excessive manganese easily forms center Segregation, leads to ingredient and the tissue odds of steel, and impaired low temperature drops hammer toughness.
P :≤0.001%, S :≤0.0012%:P, S are most important harmful elements in steel, P easily in slab center segregation, Plasticity, impact flexibility can be caused to significantly reduce, especially in low temperature, it makes steel significantly become fragile.S is easily formed in conjunction with Mn MnS reduces the low-temperature flexibility of steel, therefore strict control P, S content is wanted in this programme.
Alt:0.015~0.045%, aluminium are main deoxidant elements in steel, can significantly reduce the oxygen content in steel, together When aluminium and nitrogen combination formed AlN, can effectively refine crystal grain.But when aluminium content is more than a certain amount of in steel, easily lead to aluminium Oxide be mingled with and obviously increase, reduce the cleanliness of steel, it is unfavorable to the low-temperature flexibility of steel.
Nb:0.060~0.080%, niobium can significantly improve the austenite recrystallization temperature of steel, expand Unhydrated cement Range is easy to implement high temperature controlled rolling, reduces mill load, while niobium can also inhibit Austenite Grain Growth, has significant Refined crystalline strengthening and precipitation strength effect, for thick steel plates, Nb can both make up the reduction bring intensity decline of carbon, Crystal grain can be significantly refined again improves low-temperature flexibility.Deficiency is acted on if content is lower than 0.06%, if being higher than 0.08% cost It is higher.
Ti:0.008~0.020%, titanium is similar with effect of the niobium in steel, has stronger refined crystalline strengthening and precipitation strength to make With micro titanium can also form the precipitate of high temperature refractory at high temperature in conjunction with carbon, oxygen, be conducive to inhibit sweating heat shadow The Austenite Grain Growth for ringing area, significantly improves the toughness of welding heat affected zone.Excessive Ti can then form bulky grain in conjunction with N TiN particle, significantly reduce the low-temperature flexibility of steel.Therefore in this programme the content of Ti be designed as Trace Titanium Treatment 0.008~ 0.020%.
Cr:0.15~0.30%, the preferably weight percent content of Cr are 0.15~0.27%, further preferably Cr Weight percent content be 0.15~0.23%.The stronger solution strengthening effect of chromium, and it is cheap, it can effectively substitute The expensive alloying elements such as Mo, Ni reduce production cost.In addition, certain chromium, which is added, can also improve weather-proof, the corrosion resistance of steel And harden ability.If content is lower than 0.15%, invigoration effect can not be played；If being higher than 0.30%, the low temperature that can deteriorate steel is tough Property.
Mo:0.10~0.25%, the preferably weight percent content of Mo are 0.11~0.22%.During the element promotes by force Warm structural transformation element, effectively generation phase transformation strengthening.Meanwhile Mo has raising harden ability, uniform wall thickness group for slab Knit uniformity effect.The Mo content designed in the present invention is 0.10~0.25%.It can not work if lower than 0.10%, if high Expensive in 0.25% one side cost of alloy, on the other hand excessive Mo can promote the generation of MA, deteriorate steel plate impact flexibility.
Ni:0.10~0.25%, the preferably weight percent content of Ni are 0.10~0.23%, further preferably Ni Weight percent content be 0.13~0.19%.Nickel can effectively improve the harden ability of steel, make with certain solution strengthening With, moreover it is possible to significantly improve the low-temperature flexibility of steel.But nickel is similar with molybdenum, belongs to precious metal, easily leads to the manufacturing cost of steel substantially It improves, in addition, excessively high nickel content easily causes steel-plate iron oxide scale to be difficult to remove, leads to plate surface quality problem.
The influence of N≤0.006%, N to steel performance is similar to C, P, with the increase of N content, but the intensity of steel It significantly improves, plasticity especially toughness is significantly reduced, deteriorated weldability, cold brittleness aggravation.Therefore N must be controlled in this programme System is in 60ppm or less.
As :≤0.012%, Sb :≤0.01%, Sn :≤0.015%, Pb :≤0.01%, Bi :≤0.01%, Ca :≤ 0.006%, five-harmful elements reduce the degree of purity of steel, increase cold short, the hot-short tendency of steel, influence low-temperature flexibility, the plasticity of product Deng, therefore the lower content the better.
Why the present invention uses 1150~1200 DEG C of lower heating temperature, preferably slab heating temperature 1150~ 1175 DEG C, low temperature toughness of dropping hammer is one of most important difficult point of pipe line steel of special think gauge, and crucial control principle is to pass through The austenite grain of control before phase change is tiny to realize that the tissue after phase transformation sufficiently refines.But for special heavy plate, due to finished product Specification is thick, and roll-force can not preferably penetrate into rolled piece center portion, while center portion temperature is high, easily leads to the refinement of center portion austenite not Foot, it is therefore necessary to begin to control austenite grain size from source.According to studies have shown that austenite grain size and heating temperature Spend it is closely related, when temperature be higher than 1200 DEG C when, austenite grain can grow up rapidly, and in order to be sufficiently dissolved in steel alloy member Element, heating temperature necessarily are greater than 1150 DEG C, therefore are on the one hand to guarantee the tiny of original austenite using the heating process It homogenizes, while in turn ensuring the abundant dissolution of alloying element, ensure that other mechanical properties of the product.
Why the present invention uses the big Reduction Technology refinement original austenite grain of low temperature, and roughing end temp is controlled complete Complete 970~1010 DEG C of temperatures above of recrystallization, so that three passages are depressed after increasing as far as possible in the case where appointed condition allows Rate is to promote to recrystallize；10s~30s will be separated by between each passage of last three passage by, which controlling, is just rolled, preferably 14 ~26s, this is because in experiments it is found that: in the case where single pass depresses insufficient situation, if pressure can be added up using increasing Mode then can promote Austenite Grain Refinement, but to having time interval is wanted between this, so that recrystallization is sufficiently, but when interval When time is less than 10s, single pass recrystallization is insufficient, is also easy to produce mixed grain structure；It is then recrystallized when interval time is greater than 30s Crystal grain is grown up afterwards.
Why the present invention controls entry temperature at finishing at 925~960 DEG C, is preferably controlled within 935~955 DEG C, is Because finish rolling need to be rolled in Unhydrated cement, temperature is higher, may cause final tissue mixed crystal, temperature is too low, causes to bite Power is excessive, easily causes piling of steel accident.
Improve finish rolling compression ratio as far as possible on the basis of existing equipment；F6~F7 rack finish rolling compression ratio is controlled not Lower than 8%, exit temperature at finishing is controlled at 780~820 DEG C, primarily to flattening austenite before phase change as far as possible, is promoted Phase-change energy accumulation provides nucleation point for thinning microstructure in subsequent cooling procedure.
Why the present invention controls cooling velocity in 30~40 DEG C/s, primarily to it is uniform to obtain full plate thickness direction Acicular ferrite+granular bainite microstructure and suitable grain size.
Why the present invention controls oiler temperature control at 300~350 DEG C, primarily directed to the ingredient of think gauge X80 For the matched well of proof strength and toughness for system, obtains acicular ferrite+granular bainite tissue and need to surpass Rolled piece is quickly cooled to the temperature range.If temperature is higher than 350 DEG C, easily there is coarse, crystal boundary in the tissue of wall thickness center portion The quasi-polygonal ferrite of reduction+a small amount of pearlitic structrure, the low-temperature flexibility of severe exacerbation center portion are organized if lower than 300 DEG C In easily there is the larger-size island Ma Ao constituent element, impaired low temperature toughness.
Compared with prior art, the present invention guaranteeing power under the precondition that existing conventional production lines are not required to transformation Learn performance: Rt0.5>=570MPa, Rm>=625MPa, YR≤0.91, A50Under >=28%, HV10≤260, steel plate thickness can be greater than 22mm, until 23mm, and -20 DEG C of KV2>=300J, -15 DEG C of DWTTSA >=95%.
Detailed description of the invention
Fig. 1 is metallographic structure figure (surface) of the invention；
Fig. 2 is metallographic structure figure of the invention (at 1/4 thickness)；
Fig. 3 is metallographic structure figure (at 1/2 thickness) of the invention
Specific embodiment
The present invention is described in detail below:
Table 1 is the comparative example of various embodiments of the present invention and comparative example；
Table 2 is the main technologic parameters list of various embodiments of the present invention and comparative example；
Table 3 is various embodiments of the present invention and comparative example performance text list.
Various embodiments of the present invention produce according to the following steps:
1) after routinely being smelted and be cast into continuous casting billet, slab is heated, heating and temperature control at 1150~1200 DEG C, Time inside furnace is 200~240min；
2.) roughing is carried out, carries out reversible rolling using seven passage milling trains, and control roughing end temp 970~1010 DEG C, in which: roughing it is last fall first and the passage of falling third reduction ratio 20~21%, the reduction ratio of the second passage is 18 ~20%；And to be separated by 10s~30s between each passage of last three passage and just be rolled；Workpiece thickness after roughing Control is in 55~58mm；
3) finish rolling is carried out, is carried out using seven rack unit of F1~F7, is only passed through in F5 rack without rolling therebetween；Control Entry temperature at finishing is at 925~960 DEG C, and finish rolling overall compression ratio is not less than 60%, and in F6 and F7 rack finish rolling compression ratio Control is being not less than 8%；Exit temperature at finishing is controlled at 780~820 DEG C；
4) it is cooling to carry out rapid cooling, cooling velocity control is in 30~40 DEG C/s；
5) it is batched, oiler temperature control is at 300~350 DEG C；
6) it is air-cooled to room temperature.
The chemical component list (wt%) of 1 various embodiments of the present invention of table and comparative example
The main technologic parameters list of 2 various embodiments of the present invention of table and comparative example
Continued 2
3 various embodiments of the present invention of table and comparative example main performance detection statistics table
From table 3 it can be seen that the implementation of chemical component and technical matters in through the invention, realize think gauge (>= 22mm) the production of X80 grades of hot rolling pipeline roll of steel plate, properties are excellent, meet market demands, and manufacturing enterprise is existing without transformation There is equipment.
Above-described embodiment is only the best example, rather than a limitation of the embodiments of the present invention.

Claims (10)

1. the pipeline X80 hot-rolled coil of thickness >=22mm a kind of, chemical component and weight percent content are as follows: C:0.025 ~ 0.045%；Si:0.15~0.30%；Mn:1.70~1.85%；P≤0.001%；S≤0.0012%；Alt:0.015 ~ 0.045%；Nb: 0.060~0.080%；Ti:0.008 ~ 0.020%；Cr:0.15 ~ 0.30%；Mo:0.10 ~ 0.25%；Ni:0.10~0.25%；Harmful member The control of element: N≤0.006%, As≤0.012%, Sb≤0.01%, Sn≤0.015%, Pb≤0.01%, Bi≤0.01%, Ca≤ 0.006%, remaining is Fe and inevitable impurity；Metallographic structure are as follows: acicular ferrite and 10% no more than volume ratio content Granular bainite, grain size is at 13 ~ 14 grades.
2. a kind of pipeline X80 hot-rolled coil of thickness >=22mm as described in claim 1, it is characterised in that: the weight of Cr Degree is 0.15 ~ 0.27%.
3. a kind of pipeline X80 hot-rolled coil of thickness >=22mm as claimed in claim 1 or 2, it is characterised in that: the weight of Cr Measuring degree is 0.15 ~ 0.23%.
4. a kind of pipeline X80 hot-rolled coil of thickness >=22mm as described in claim 1, it is characterised in that: the weight of Mo Degree is 0.11 ~ 0.22%.
5. a kind of pipeline X80 hot-rolled coil of thickness >=22mm as described in claim 1, it is characterised in that: the weight of Ni Degree is 0.10 ~ 0.23%.
6. the pipeline X80 hot-rolled coil of thickness >=22mm as claimed in claim 1 or 5 a kind of, it is characterised in that: the weight of Ni Measuring degree is 0.13 ~ 0.19%.
7. producing a kind of method of the pipeline of thickness >=22mm as described in claim 1 with X80 hot-rolled coil, step:
1) after routinely smelting and being cast into continuous casting billet, slab is heated, heating and temperature control is at 1150 ~ 1200 DEG C, in furnace Time is 200 ~ 240min；
2.) roughing is carried out, carries out reversible rolling using seven passage milling trains, and control roughing end temp at 970 ~ 1010 DEG C, In: roughing it is last fall first and the passage of falling third reduction ratio 20 ~ 21%, the reduction ratio of the second passage is 18 ~ 20%；And To be separated by 10s ~ 30s between each passage of last three passage just to be rolled；Workpiece thickness control exists after roughing terminates 55~58mm；
3) finish rolling is carried out, is carried out using seven rack unit of F1 ~ F7, is only passed through in F5 rack without rolling therebetween；Control finish rolling For inlet temperature at 925 ~ 960 DEG C, finish rolling overall compression ratio is not less than 60%, and exists in F6 and the control of F7 rack finish rolling compression ratio Not less than 8%；Exit temperature at finishing is controlled at 780 ~ 820 DEG C；
4) it is cooling to carry out rapid cooling, cooling velocity control is in 30 ~ 40 DEG C/s；
5) it is batched, oiler temperature control is at 300 ~ 350 DEG C；
6) it is air-cooled to room temperature.
8. the method for producing the pipeline X80 hot-rolled coil of thickness >=22mm a kind of as claimed in claim 7, feature exist In: the slab heating temperature is at 1150 ~ 1175 DEG C.
9. the method for producing the pipeline X80 hot-rolled coil of thickness >=22mm a kind of as claimed in claim 7, feature exist In: to be separated by 14s ~ 26s between each passage of last three passage and just be rolled.
10. the method for producing the pipeline X80 hot-rolled coil of thickness >=22mm a kind of as claimed in claim 7, feature exist In: the entry temperature at finishing is at 935 ~ 955 DEG C.
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