CN105886912A - Low-compression-ratio and thick-specification X70-grade gas transmission pipeline steel and production method - Google Patents

Low-compression-ratio and thick-specification X70-grade gas transmission pipeline steel and production method Download PDF

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CN105886912A
CN105886912A CN201610269204.4A CN201610269204A CN105886912A CN 105886912 A CN105886912 A CN 105886912A CN 201610269204 A CN201610269204 A CN 201610269204A CN 105886912 A CN105886912 A CN 105886912A
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steel
rolling
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CN105886912B (en
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徐锋
徐进桥
郭斌
孔君华
李利巍
崔雷
邹航
刘小国
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Wuhan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

Low-compression-ratio and thick-specification X70-grade gas transmission pipeline steel is prepared from, by weight percent, 0.03-0.075% of C, 0.15-0.35% of Si, 1.30-1.90% of Mn, not larger than 0.015% of P, not larger than 0.002% of S, not larger than 0.006% of N, 0.035-0.065% of Nb, 0.025-0.05% of V, 0.015-0.025% of Ti, 0.1-0.40% of Cr, 0.1-0.2% of Ni and 0.10-0.25% of Mo. Production steps include heating of casting blanks with the thickness ranging from 225 mm to 235 mm, rough rolling, high-pressure water descaling, fine rolling, cooling, straightening and standby application. According to the low-compression-ratio and thick-specification X70-grade gas transmission pipeline steel, the X70-grade pipeline steel with the thickness being 30 mm or above can be produced through the continuous casting blanks with the thickness being 230 mm, the Rt0.5 of the product ranges from 500 MPa to 580 MPa, the Rm of the product ranges from 600 MPa to 650 MPa, the ratio of the Rt0.5 to the Rm is not larger than 0.90, and the elongation A50 is not smaller than 24%; at -20 DEG C, the impact energy KV2 is not smaller than 250 J; at -15 DEG C, the DWTT fracture surface shear rate SA is not smaller than 95%; and HV10 <=235.

Description

A kind of low compression ratio think gauge X70 level steel for gas delivering pipeline and production method
Technical field
The present invention relates to a kind of pipe line steel and production method thereof, specifically belong to a kind of low compression ratio think gauge X70 level defeated Gas pipeline steel and production method.
Background technology
The natural gas resource almost all of China concentrates on west area, is scattered in inverse ratio, greatly with the population density of China The burning of the Fossil fuels such as the coal of amount, oil brings serious haze problem to Chinese environmental.China's economic must protected Energy crisis is solved while holding rapid growth, to this end, the natural gas of country's Devoting Major Efforts To Developing western part cleaning, built transfering natural gas from the west to the east One, two wires, currently builds three lines, and has planned four, five, six lines etc..Hi-grade steel, heavy caliber, a big ancient piece of jade, round, flat and with a hole in its centre are thick, high-pressure delivery Become the developing direction of pipe-line construction from now on.But there is more accident in the Hi-grade steel X70 ~ X80 of thin ancient piece of jade, round, flat and with a hole in its centre specification in construction, For security consideration, country needs to develop X70-X80 rank big ancient piece of jade, round, flat and with a hole in its centre thickness pipe line steel to meet the conveying of the efficient energy in a hurry.
The angle controlled from traditional handicraft, the compression ratio of pipe line steel must assure that and could meet API more than 10 times The obdurability coupling requirement of 5L, and the requirement of grade of steel more high compression ratio is the biggest.At present, continuous casting in China machine strand size mainly has 300mm, 250mm, 230mm, be only capable of producing thickness less than below 30mm pipe line steel traditionally.
Through retrieval, before the present patent application, China Patent Publication No. is the document of CN103937950A, it discloses " one Plant the production technology of low compression ratio think gauge high-grade pipe line steel ", its component and technique are mainly (C:0.03 ~ 0.08%；Si: 0.15 ~ 0.35%, Mn:1.5 ~ 2.0%；Nb:0.05 ~ 0.09%；Ti:0.015 ~ 0.025%；Mo≤0.25%；Cu≤0.35%；Ni≤ 0.30%；Cr :≤0.030%, use 250mm continuous casting billet by controlling slab reheating temperature, thick, finish rolling rolling total reduction and Rolling temperature and open the technological parameter such as cold, final cooling temperature, rate of cooling and obtain think gauge X80 pipe line steel, mechanical property is (Rt0.5:550 ~ 591MPa, Rm:694 ~ 732MPa ,-20 DEG C of KV2/ J >=300J ,-15 DEG C, DWTT: >=90%, although it can Production wall thickness is the Hi-grade steel pipe line steel of 25 ~ 33mm, but its Ni+Cu+Mo >=0.6%, cost of alloy is higher, retouches in patent meanwhile Last percentage pass reduction >=15% when rough rolling step meets deformation temperature lower limit stated, does not indicates that lowest temperature is many actually Few, meanwhile, actual production makes deformation of rolled wire drag excessive due to low temperature, is difficult to accomplish.
The patent documentation separately having China Patent Publication No. to be CN10363919A, discloses and " makes under the conditions of a kind of small reduction ratio Method with continuous casting billet production flow line steel plate ".It uses 300mm continuous casting billet production 40-50mm wide cut to reach the spy of 3200-4000mm Thick pipe line steel.Its component and technique are mainly (C:0.05 ~ 0.10%；Si:0.15 ~ 0.30%；Mn:1.0 ~ 2.0%;Nb:≤ 0.05%;V :≤0.05%, Ti :≤0.05%, use 300mm strand to cool down after reheating, two-phase control rolling, power Performance is (Rt0.5:511 ~ 541MPa；Rm:603 ~ 623MPa ,-20 DEG C of KV2/J: >=200 ~ 250J ,-10 DEG C, DWTT:50 ~ 60%), although it can produce the pipe line steel that wall thickness is 40 ~ 50mm, alloy addition level is the most little.But existing, impact flexibility is not Height, reluctantly higher than 200J, particularly-10 DEG C DWTT performances only 50 ~ 60%, it is impossible to meet engineering requirement.
Additionally, China Patent Publication No. is the document of CN1927486A, describe " low compression ratio high grade pipe line steel Production technology ", it is indicated that produce the production technology of 17 ~ 22mmX70 level pipeline pipeline steel through steekle mill with 150mm continuous casting billet.Although Its compression ratio is relatively low, but requires that Molten Steel Cleanliness is excessively strict, and wherein the content of S is less than 6ppm, and P content is less than 70ppm, right Do not accomplish for most of smelting iron and steel enterprises at all.150mm continuous casting billet domestic product line is little simultaneously, and the equipment that produces is with conventional Product line is different, and product thickness is in the range of conventional products, it is impossible to meet the pipeline engineering demand to big wall thickness (>=30mm).
From the point of view of from the existing document being produced think gauge Hi-grade steel pipe line steel by low compression ratio is reported, all exist logical Cross and add the highest alloy and sacrifice the deficiency of the think gauge high-grade pipe line steel that impact reaches with block hammer performance；For adopting Rolling with the thinnest continuous casting billet, though having produced high-grade pipe line steel in the case of low-pressure ratio, but thickness is maximum Only 22mm, the contradiction that thickness is not enough highlights.
The present invention mainly uses conventional 230mm continuous casting billet, it is to avoid enterprise invests the special think gauge continuous casting billet of enlarging separately, passes through Control to smelt composition, reheat, thick, finish rolling rolling and control cold technique reach to produce in the case of compression ratio only 6.0 ~ 7.7 30 ~ The purpose of the X70 pipe line steel of 38mm high tenacity.
Summary of the invention
The invention reside in the deficiency overcoming above-mentioned technology to exist, it is provided that a kind of in guarantee mechanical property and without adding Cu's Under premise, using the most frequently used 230mm continuous casting billet to produce thickness, to reach the low compression ratio think gauge X70 level of 30 ~ 38 mm pipe line steels defeated Gas pipeline steel and production method.
Realize the measure of above-mentioned purpose:
A kind of low compression ratio think gauge X70 level steel for gas delivering pipeline, its component and weight percent content be: C:0.03-0.075%, Si:0.15 ~ 0.35%, Mn:1.30 ~ 1.90%, P :≤0.015%, S :≤0.002%, N :≤0.006%,Nb: 0.035 ~ 0.065%, V:0.025 ~ 0.05%, Ti:0.015 ~ 0.025%, Cr:0.1 ~ 0.40%, Ni:0.1 ~ 0.2%,Mo: 0.10 ~ 0.25%, remaining is Fe and inevitably impurity；Metallographic structure is: top layer: acicular ferrite+a small amount of bainite, thickness of slab 1/4 and 1/2 tissue is all For: acicular ferrite+a small amount of granular ferrite.
A kind of method producing low compression ratio think gauge X70 level steel for gas delivering pipeline, its step:
1) to component and weight percent content it is: C:0.03-0.075%, Si:0.15 ~ 0.35%, Mn:1.30 ~ 1.90%, P :≤ 0.015%, S :≤0.002%, N :≤0.006%,Nb: 0.035 ~ 0.065%, V:0.025 ~ 0.05%, Ti:0.015 ~ 0.025%, Cr:0.1 ~ 0.40%, Ni:0.1 ~ 0.2%,Mo: 0.10 ~ 0.25%, remaining is for Fe and inevitably impurity, thickness are 225- The strand of 235mm heats, and its heating and temperature control is at 1120-1180 DEG C, and makes soaking zone temperature retention time be not less than 40 points Clock, is not less than 250 minutes total heat time heating time；
2) carrying out roughing, control recrystallization zone rolling temperature, at 1050-1115 DEG C, uses maximum rolling force to roll in deformation process System, maximum rolling force is not less than 7500t；Rate of deformation controls at 4 ~ 5/s；Passage is less than 10s, last three passages interval time Accumulation reduction ratio >=22%；Treat temperature workpiece thickness at 70-90mm, recrystallization zone total reduction is 60-70%；
3) routine carries out high-pressure water descaling, controls the steel billet temperature start rolling temperature in finish rolling；
4) carrying out finish rolling, control its start rolling temperature at 850-950 DEG C, finishing temperature, at 750-850 DEG C, rolls 6 ~ 9 passages altogether, tired Long-pending reduction ratio 55-65%, and make down the 3rd and second accumulation reduction ratio >=20% of passage；
5) cool down, control to open cold temperature at 770-830 DEG C, under cooldown rate is 15-35 DEG C/s, is cooled to 300 ~ 400 ℃；
6) align, stand-by.
Each element and the effect of main technique and mechanism in the present invention
C: in the present invention, carbon content is 0.03 ~ 0.075%.Carbon is one of element of indispensable raising steel strength in steel, with Time can form microalloy carbide with the effect such as Ti, Nb in steel, play precipitation strength effect, if its content is more than 0.075%, Then can damage the toughness of steel, not have again effect less than 0.03,
Si: in the present invention, Si content is 0.15 ~ 0.35%.This yuan have solution strengthening and deoxidation, and content is less than 0.15% nothing Method works, if but simultaneously higher than 0.35%, the moulding of pipe line steel, toughness, rushing especially for welding heat affected zone can be deteriorated Hit reduction notable.
Mn: in the present invention, Mn content is 1.30 ~ 1.90%.This element primarily serves the purpose of expansion austenite stable region, expands heat Processing temperature region, beneficially fining ferrite grains size, improve yield strength and the tensile strength of steel.In the present invention, for Material at low temperature to be ensured impact and DWTT performance, the addition of Mn necessarily be greater than 1.3% just can play the effect of making up, as content is high In 1.9% notable deterioration Plate Welding performance.
Nb: in the present invention, Nb content is 0.035 ~ 0.065%.The notable crystal grain thinning of niobium energy also improves tensile strength.Niobium is at this In the During Controlled Rolling of invention, prevention original austenite can be played in the reheating stage and grow up the most rapidly, at rough rolling step Significantly improve recrystallization temperature, reduce mill load, grown up by suppression recrystal grain, can fining austenite grains size. During roller repairing, Nb(C, N) precipitation of small particle, the effect of precipitation strength can be played, Nb is to crystal grain refinement and separates out work Change with the change with content, if less than 0.03%, being unable to reach refined crystalline strengthening purpose, if higher than 0.065%, there is waste Problem, cause high cost.
Ti: in the present invention, the content of Ti is 0.015 ~ 0.025%.. titanium is a kind of strong carbide and nitride forms unit Element, reheats at steel and can stop Austenite Grain Growth in high temperature austenite district, rough rolling process, separates out at cooling stage Small and dispersed TiC can play significant precipitating reinforcing effect, thus effectively improves armor plate strength, and content is less than 0.015%, Then not enough to original austenite grain refining effect, if higher than 0.025%, being likely to be formed bulky grain TiN, being enriched in steel plate heart portion, Significantly reduce steel plate toughness.
N: N≤0.006% in the present invention.Belong to normal remaining in converter steel, can combine with titanium in steel (Ti), niobium (Nb) Form TiN, NbN to separate out, play suppression Austenite Grain Growth and precipitation strength effect.N Yu Ti of excess forms bulky grain TiN, deteriorates toughness.
Cr: in the present invention, Cr content is 0.1 ~ 0.40%, this element is solution strengthening element and improves steel plate quenching degree, promotees Enter middle temperature tissue tissue to change and Second Phase Precipitation, promote armor plate strength.Make up the intensity deficiency that low-carbon (LC) causes, if being higher than 0.40%, on the one hand cause the waste of cost, on the other hand cause carbon equivalent to raise, deteriorate weldability.
Ni: in the present invention, content is 0.1 ~ 0.25%, these two kinds of elements are solution strengthening element and improve steel plate quenching degree, Promote that middle temperature tissue tissue changes and Second Phase Precipitation, promote armor plate strength.Make up the intensity deficiency that low-carbon (LC) causes.If it is higher than 0.25% 1 aspect causes the waste of cost, on the other hand causes carbon equivalent to raise, and deteriorates welding performance.
Mo: in the present invention, content is 0.10 ~ 0.25%, this element is among the austenite stabilizing elements and through hardening element, in the present invention In can strongly facilitate middle temperature structural transformation, play the histological difference uniformly caused along plate thickness direction by rate of cooling inequality excessive Effect.Belong to residual elements less than 0.10%, do not have effect, the middle temperature structural transformation product of strong refinement, shape higher than 0.25% Becoming MA island band, cause armor plate strength too high, toughness declines.Mo belongs to noble element simultaneously, relatively costly.
At process aspect, the present invention takes into account steel plate obdurability coupling while considering low cost, and main innovation point is: 1) relatively low reheating temperature 1120 ~ 1180 DEG C, it is ensured that low C, low Nb, low Cr, Ni, Mo component system under original austenite brilliant Grain refinement controls.2) abundant rolling temperature control when rolling in recrystallization zone, utilizes the method shortening road minor tick to use multiple tracks The mode of secondary accumulative pressure carries out the crystal grain refinement of austenite.3) use accumulative press control mode equally in the finish rolling stage, allow Steel plate austenite before phase transformation is sufficiently flat, improves strain accumulation energy and defect point, improves nucleation site.4) higher cooling rate is used (15 ~ 35 DEG C/s) realize " with water cash equivalent " and carry out being quickly cooled to middle temperature structural transformation region, simultaneously with Mo homogenization along wall thickness The structural homogenity in direction.
The present invention is compared with prior art: thickness produced by the conventional continuous casting billet that thickness of strand can be used to be 230mm Reach 30mm and above X70 level pipe line steel so that do not have the production line of special thick continuous casting billet also can produce think gauge Hi-grade steel Pipe line steel, has adapted to the development trend in market, improves the market competitiveness of pipe line steel.And the yield strength of product of the present invention Rt0.5In 500 ~ 580MPa, tensile strength RmIn 600 ~ 650MPa, yield tensile ratio Rt0.5 /Rm≤ 0.90, elongation percentage A50>=24%,；- 20 DEG C of ballistic work KV2>=250J ,-15 DEG C of DWTT section shear rate SA >=95%；Hardness number HV10≤235。
Accompanying drawing explanation
Fig. 1 is the top layer metallographic structure figure of 30mm thickness product of the present invention；
Fig. 2 is metallographic structure figure at 1/4 thickness of 30mm thickness product of the present invention；
Fig. 3 is metallographic structure figure at 1/2 thickness of 30mm thickness product of the present invention.
Detailed description of the invention
Below the present invention is described in detail:
Table 1 is the value list of various embodiments of the present invention；
Table 2 is the main technologic parameters list of various embodiments of the present invention；
Table 3 is various embodiments of the present invention horizontal main performance detection statistics tables.
Various embodiments of the present invention produce according to following steps:
1) heating the strand that thickness is 225-235mm, its heating and temperature control is at 1120-1180 DEG C, and makes soaking zone Temperature retention time is not less than 40 minutes, and total heat time heating time is not less than 250 minutes；
2) carrying out roughing, control recrystallization zone rolling temperature, at 1050-1115 DEG C, uses maximum rolling force to roll in deformation process System, maximum rolling force is not less than 7500t；Rate of deformation controls at 4 ~ 5/s；Passage is less than 10s, last three passages interval time Accumulation reduction ratio >=22%；Treat temperature workpiece thickness at 70-90mm, recrystallization zone total reduction is 60-70%；
3) routine carries out high-pressure water descaling, controls the steel billet temperature start rolling temperature in finish rolling；
4) carrying out finish rolling, control its start rolling temperature at 850-950 DEG C, finishing temperature, at 750-850 DEG C, rolls 6 ~ 9 passages altogether, tired Long-pending reduction ratio 55-65%, and make down the 3rd and second accumulation reduction ratio >=20% of passage；
5) cool down, control to open cold temperature at 770-830 DEG C, under cooldown rate is 15-35 DEG C/s, is cooled to 300 ~ 400 ℃；
6) align, stand-by.
Composition value list (wt%) of table 1 various embodiments of the present invention and comparative example
Table 2 various embodiments of the present invention and the cooling controlling and rolling controlling process of comparative example
Illustrate: table 1 and the data not one-to-one relationship in table 2.
Table 3 various embodiments of the present invention and comparative example horizontal main performance detection statistics table
From table 3 it can be seen that the present invention is by 230mm continuous casting billet, in the case of compression ratio is only 6.0-7.7, by taking Low-carbon (LC) route, carries out intensity with the Cr that cost of alloy is relatively low as main intensified element and makes up, by controlling in thick, finishing stands Total reduction and passage accumulation pressure process and rolling temperature obtain the X70 level pipeline pipeline steel of 30 ~ 38mm think gauge, have excellent Good intensity and toughness coupling, particularly low-temperature impact toughness and low temperature block hammer performance.
This detailed description of the invention is only and most preferably enumerates, the not restricted enforcement to technical solution of the present invention.

Claims (2)

1. a low compression ratio think gauge X70 level steel for gas delivering pipeline, its component and weight percent content be: C:0.03- 0.075%, Si:0.15 ~ 0.35%, Mn:1.30 ~ 1.90%, P :≤0.015%, S :≤0.002%, N :≤0.006%,Nb: 0.035 ~ 0.065%, V:0.025 ~ 0.05%, Ti:0.015 ~ 0.025%, Cr:0.1 ~ 0.40%, Ni:0.1 ~ 0.2%,Mo: 0.10~ 0.25%, remaining is Fe and inevitable impurity；Metallographic structure is: top layer: acicular ferrite+a small amount of bainite, thickness of slab 1/4 It is with 1/2 tissue: acicular ferrite+a small amount of granular ferrite.
2. a kind of method producing low compression ratio think gauge X70 level steel for gas delivering pipeline, its step:
1) to component and weight percent content it is: C:0.03-0.075%, Si:0.15 ~ 0.35%, Mn:1.30 ~ 1.90%, P :≤ 0.015%, S :≤0.002%, N :≤0.006%,Nb: 0.035 ~ 0.065%, V:0.025 ~ 0.05%, Ti:0.015 ~ 0.025%, Cr:0.1 ~ 0.40%, Ni:0.1 ~ 0.2%,Mo: 0.10 ~ 0.25%, remaining is for Fe and inevitably impurity, thickness are 225- The strand of 235mm heats, and its heating and temperature control is at 1120-1180 DEG C, and makes soaking zone temperature retention time be not less than 40 points Clock, is not less than 250 minutes total heat time heating time；
2) carrying out roughing, control recrystallization zone rolling temperature, at 1050-1115 DEG C, uses maximum rolling force to roll in deformation process System, maximum rolling force is not less than 7500t；Rate of deformation controls at 4 ~ 5/s；Passage is less than 10s, last three passages interval time Accumulation reduction ratio >=22%；Treat temperature workpiece thickness at 70-90mm, recrystallization zone total reduction is 60-70%；
3) routine carries out high-pressure water descaling, controls the steel billet temperature start rolling temperature in finish rolling；
4) carrying out finish rolling, control its start rolling temperature at 850-950 DEG C, finishing temperature, at 750-850 DEG C, rolls 6 ~ 9 passages altogether, tired Long-pending reduction ratio 55-65%, and make down the 3rd and second accumulation reduction ratio >=20% of passage；
5) cool down, control to open cold temperature at 770-830 DEG C, under cooldown rate is 15-35 DEG C/s, is cooled to 300 ~ 400 ℃；
6) align, stand-by.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109082601A (en) * 2018-09-03 2018-12-25 本钢板材股份有限公司 A kind of acid-resisting corrosion X70MS line steel hot rolling roll bending and its manufacturing method
CN111748741A (en) * 2020-06-30 2020-10-09 武汉钢铁有限公司 Thick pipeline steel and low compression ratio production process thereof
CN111748742A (en) * 2020-06-30 2020-10-09 武汉钢铁有限公司 Super-thick-wall X70 grade marine acid-resistant pipeline steel and preparation method thereof
CN112680659A (en) * 2020-12-04 2021-04-20 安阳钢铁股份有限公司 Low-compression-ratio economical X70 pipeline steel and production method thereof
CN115287428A (en) * 2021-11-19 2022-11-04 中南大学 Method for regulating and controlling dual-phase structure of X70-grade pipeline steel and increasing low-temperature toughness

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