CN106319387B - A kind of X80 large-deformation-resistance pipeline steels and manufacturing method - Google Patents

Abstract

The present invention discloses a kind of X80 large-deformation-resistance pipeline steels and manufacturing method, the mass percent of chemical composition is C 0.04% 0.09% in the steel, Si 0.15% 0.55%, Mn 1.50% 1.75%, Nb 0.04% 0.10%, V 0.02% 0.08%, Ti 0.01% 0.03%, Cu 0.15% 0.55%, Ni 0.15 0.55%, Cr 0 0.15%, Mo 0.15% 0.45%, Al 0.025% 0.045%, N 0.0002% 0.011%, P≤0.015%, S≤0.005%, remaining be Fe and it is other be inevitable impurity element.Using following process route：Stock → converter or electric furnace smelting → external refining → casting → slab reheating → controlled rolling → control cooling, after two-phase section quenching, do not use using tempering or tempering process；Compared with prior art, have the advantages that lower yield tensile ratio, uniform elongation higher, obdurability match more preferable, steel plate is small with plate poor performance, thickness direction structural homogenity is high, band-like rank is low etc..

Description

A kind of X80 large-deformation-resistance pipeline steels and manufacturing method

Technical field

The invention belongs to technical field of pipeline steel, it is related to a kind of X80 large-deformation-resistance pipeline steels and manufacturing method, especially relates to And a kind of X80 large-deformation-resistance pipeline Wide and Thick Slabs and preparation method thereof prepared using two-phase section process for quenching.Using the present invention The pipeline Wide and Thick Slab of preparation can be applied to manufacture and be based on stress design area Longitudinal SAW Pipe.

Background technology

As petroleum resources demand increasingly increases, the investment construction of new oil gas field gradually increases.Due to the production of oil gas Ground and area of consumption generally require to pass through the geological conditions such as permafrost band, earthquake zone badly regional, it is therefore desirable to long oil/gas pipe Road meets the requirement based on stress design：The lateral performance of steel pipe meets traditional requirement based on stress design, longitudinal performance Feature with anti-large deformation.The typical performance parameter for characterizing anti-large deformation feature is that yield tensile ratio is low (Rt0.5/Rm≤0.80), Uniform elongation height (UEL >=10%), stress-strain diagram are thole top-type.In order to which the ess-strain for quantifying thole top-type is bent Line refers to usually using strain hardening exponent n or stress ratio Rt1.5/Rt0.5, Rt2.0/Rt1.0, Rt5.0/Rt1.0, stress ratio Mark has many advantages, such as that measurement is easy relative to n, and description curve shape is more accurate.

In order to reach based on the property of resisting large deformation needed for stress design, there are two types of means：1) thick walled steel tube is used；2) it adopts With the Plate Production steel pipe of duplex structure.In actual application, both methods is not isolated.If only with wall is increased Thick mode improves anti-large deformation ability, and steel plate thickness is often especially thick, industrialized production difficulty is big and cost of investment drastically Increase.Based on this, large-deformation resistance pipe the characteristics of being provided with heavy wall and two-phase simultaneously at present.

Currently, the large deformation Pipeline Steel Plate of production heavy wall two-phase, there are two types of process routes, first, rolled after controlled rolling and controlled cooling The supply of material, reuses after being heat-treated one is the steel plate after controlled rolling and controlled cooling.Because steel plate wall thickness is big, the life of traditional TMCP techniques The dual phase sheet steel of production exists with the disadvantages such as plate difference is big, low temperature DWTT properties percent of pass is low in performance, organizationally there is band The deficiencies of shape rank is high, along wall thickness direction nonuniform organization.

In order to overcome these technological deficiencies, heat treatment procedure can be increased on the basis of TMCP techniques.Currently, using heat The open source literature that processing mode produces large deformation pipe line steel is still rare.Patent CN201110054270.7 discloses a kind of " tool Have the large-deformation-resistance pipeline steel and its production method of excellent aging resistance ", steel plate roll rear water cooling speed it is low, terminate cooling temperature Height is also easy to produce coarse MA, unfavorable to subsequent heat treatment technology controlling and process；Patent CN201010266539.3 discloses a kind of " heat treatment Large-deformation-resistance pipeline steel and preparation method thereof prepared by method ", steel plate thickness 10-25mm, and it is not directed to rolled steel plate Production technology；Patent CN201010289370.3 discloses " low yield strength ratio fine grain, high strength Pipeline Steel Plate and its production method ", In-between base lets cool 1.7-2.0 times of the thin only finished steel plate of thickness and rolled final cooling temperature height is also easy to produce coarse rich carbon phase MA constituent elements；Patent CN201010235925.6 discloses a kind of " side of manufacturing pipeline steel medium plate with excellent tenacity through normalizing rolling Method ", which is not intended to production large-deformation-resistance pipeline steel, and its grade of steel is only X65.

Compared with the heat treatment process used by the above-mentioned patent, present invention employs be more advantageous to improve the anti-large deformation of steel plate The two-phase section quenching technology of performance, the technology have many advantages, such as that cooling velocity higher, the control of steel plate tissue ratio are accurate.It increases After thinking about it quenching process, although in process it is complicated some, structural homogenity, properties percent of pass and the stabilization of steel plate Property increases substantially, and is especially more than the steel plate for anti-large deformation of 25mm to thickness, the cost performance for being heat-treated production is apparent Better than the cost performance of TMCP productions.

In conclusion existing low temperature DWTT poor performances, banded structure rank for X80 level large-deformation resistance pipe line steels The main problems such as height, plate thickness direction nonuniform organization, are well solved using technical scheme of the present invention.

Invention content

The object of the present invention is to provide a kind of X80 large-deformation-resistance pipeline steels and preparation method thereof, to solve current TMCP works It is existing with shortcomings such as big, the banded structure rank height of plate difference performance difference during skill production large-deformation-resistance pipeline steel, together When further produce that thickness specification is higher to be based on stress design area Wide and Thick Slab, to meet, X80 and the above rank are anti-big to be become The requirement of Wide and Thick Slab used in shape pipe line steel.

Finished steel plate thickness is indicated with t (unit, mm) in the present invention.

The purpose of the present invention is achieved through the following technical solutions：

X80 large-deformation-resistance pipeline steels of the present invention, it is characterised in that：The mass percent of chemical composition is C in the steel 0.04%-0.09%, Si 0.15%-0.55%, Mn 1.50%-1.75%, Nb 0.04%-0.10%, V 0.02%- 0.08%, Ti 0.01%-0.03%, Cu 0.15%-0.55%, Ni 0.15-0.55%, Cr 0-0.15%, Mo 0.15%-0.45%, Al 0.025%-0.045%, N 0.0002%-0.011%, P≤0.015%, S≤0.005%, It is remaining be Fe and it is other be inevitable impurity element.

The destination organization of moderate resistance large deformation Pipeline Steel Plate of the present invention is by apparent two phase composition of nonhomogeneous hardness, wherein soft phase is Ferrite, including polygonal ferrite, quasi-polygonal ferrite or their any mixture；Hard is mutually bainite, MA groups Member, martensite or their any mixture；Ferritic volume fraction is 40%-60%；Ferrite crystal grain average diameter is 4-10um。

Selection two-phase structure is based on considered below：Ferrite as soft phase, can provide low yield strength with it is high Uniform elongation；Bainite etc. is hard mutually can to provide high-tensile；Soft or hard Phase Proportion appropriate, may be implemented intensity, low temperature Toughness, the matched well of property of resisting large deformation, to meet the whole requirement based on stress design pipe line steel.Ferrite When score is identical, increase ferrite grain size, is conducive to improve uniformly extension numerical value and reduction yield tensile ratio；Ferrite crystal grain mistake In coarse, the low-temperature flexibility of steel plate can be adversely affected.Therefore, the ferrite volume fraction that the present invention chooses is 40%- 60%, ferrite average diameter is 4-10um.

The effect of main constituents is as follows in steel of the present invention：

C：Most economical in steel, most basic intensified element can significantly improve the strong of steel by solution strengthening and precipitation strength Degree, but improve C content and to the ductility of steel, toughness and be welded with negative effect, the evolution of modern age pipe line steel is constantly to drop The process of low C content.When C content is too low, the precipitation enhancement of the elements such as Nb cannot be given full play to.Therefore of the invention by C Content range is set as 0.04%-0.09%.

Si：It is for deoxidation in steelmaking process and the intensity for improving matrix that Si, which is added, and Si also has inhibition cementite to be formed Effect.If the toughness of the Si of excessive addition, base material and its welding heat affected zone will significantly reduce, field welding procedure performance It is deteriorated.Therefore, Si contents are set as 0.15%-0.55% in the present invention.

Mn：The intensity that steel is improved by solution strengthening is that compensation causes loss of strength because C content reduces in pipe line steel Main and most economical intensified element.Mn still expands the element of γ phase regions, can reduce γ → α phase transition temperatures of steel, drop Help to obtain tiny phase-change product during temperature, the toughness of steel can be improved, reduce ductile-brittle transition temperature；In temperature-rise period In, it can realize ferrite precipitation in lower temperature and grow up.The content of Mn is improved, the quenching degree of steel increases, and content increases to After to a certain degree, welding performance can be caused to decline the toughness of especially severe exacerbation welding heat affected zone.In addition, excessively high Mn contains Amount can also increase continuous casting billet center segregation, and the anisotropy of plate property is made to increase.In order between proof strength and low-temperature flexibility Balance and higher slab quality, Mn content ranges of the invention be designed as 1.50%-1.75%.

Nb：It is one of most important micro alloying element in modern pipe line steel, it is fairly obvious to the effect of crystal grain refinement.It is logical The recovery and recrystallization that NbC strain induced precipitates during hot rolling hinder deformed austeaite is crossed, is cooled down by controlled rolling and control So that the deformed austeaite group of non-recrystallization zone rolling is woven in and be changed into tiny phase-change product when phase transformation, so that steel has high intensity And high tenacity.The present invention is exactly that C content is coordinated to add the effect that appropriate Nb plays NbC, Nb content ranges 0.04%-0.10%.

V：It is combined with C in steel or N, there is very strong precipitation strength effect.Compared with Nb, carbonitride dissolving-analysis containing V It is low to go out equilibrium temperature, is conducive to back dissolving and precipitation under lower heating temperature condition, to play anchoring crystal boundary crystal grain thinning Effect.It is heated in two-phase section, the carbonitride of Nb, Ti are unable to back dissolving, and have the tendency that growing up, and V with back dissolving because can not be deposited In this problem, therefore it is more suitable for the effects that two-phase section heating is using to realize crystal grain refinement, precipitation strength.Excessive V is to even Casting process is unfavorable, therefore the V content range 0.02%-0.08% that the present invention chooses.

Ti：It is strong solid N element, the stoichiometric ratio of Ti/N is 3.42, and steel can be fixed using 0.01% or so Ti The N of middle 30ppm or so can form the TiN precipitated phases of tiny high-temperature stable in sheet billet continuous casting.This tiny TiN particles Austenite Grain Growth when slab reheats can be effectively inhibited, the solid solubility of Nb, V in austenite is helped to improve, changes The impact flexibility of kind welding heat affected zone.When the content of Als is too low (as being less than 0.005%), Ti can form oxide, in these Raw particle can play the role of Intragranular Acicular Ferrite forming core core, refinement welding heat affected zone tissue.In order to obtain this effect, At least to add 0.005%Ti.When Ti additive amounts are more than certain certain value, TiN particles will be roughened, the precipitation enhancement of TiC Show, low-temperature flexibility is caused to deteriorate.Therefore, the present invention chooses Ti content ranges 0.01%-0.03%.

Al：The presence of Al also plays the role of thinning microstructure typically as the deoxidier in steel.But when the content of Al Excessively, the amount of aluminium oxide nonmetal inclusion increases to reduce the cleanliness factor of steel.The too low then deoxidation of Al content is insufficient, and Ti etc. is easy Oxidizing elemental recovery rate is low, therefore the content range of Al is set as 0.025%-0.045%.

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 Being added mainly improves Cu caused red brittleness in steel, and Ni itself is also beneficial to low-temperature flexibility.In think gauge pipe line steel Intensity caused by due to water cooling intensity caused by the increase of thickness is insufficient is can also compensate for decline.The present invention chooses Cu0.15%- 0.55%, Ni 0.15%-0.55%, when which adds, effect is more preferable.

Cr、Mo：Cr, Mo element are added, CCT curve can be made to move to right, the stability of austenite increases, to promote bayesian Body phase transformation, to control, phase-change organization plays an important role, and when Cr contents are less than 7%, A3 points decline, and phase transformation turns to low temperature direction Become, tissue can be made further to refine, structure refinement is conducive to the improvement of low-temperature flexibility.During heat treatment procedure, suitably The optimization of heat treatment heating temperature and soaking time may be implemented in Cr, Mo content.In order to obtain intensity, plasticity and toughness Reasonably combined, the present invention chooses Cr 0%-0.15%, Mo 0.15%-0.45%, which presses Cr:Mo=1:When 2 addition, It is better.

N：N is one of inevitable impurity element in steel, and content is unsuitable excessively high, but the nitridations such as N and Al, Ti, Nb, V Object formation element chemical combination, can play the role of anchoring crystal boundary crystal grain thinning and precipitation strength, therefore N element is not got in steel Low better, the content range that the present invention chooses N is 0.0002%-0.011%

P、S：It is inevitable impurity element in steel, it is desirable to more lower better.For smelting cost and production technology Limitation, and cannot be unconfined low.Therefore, P, S upper content limit are set as 0.015% and 0.005% by the present invention.By ultralow S (being less than 50ppm) and Ca processing carry out inclusion morphology control to sulfide, can make the low-temperature flexibility of raising pipe line steel.

A kind of X80 large-deformation-resistance pipeline steels of the present invention be thickness targets be 26.4mm and its more than, steel plate use 230mm- The TMCP rolled steel plates that 300mm thickness steel billet is produced on cut deal reciprocating rolling mill.

TMCP rolled steel plates used in a kind of X80 large-deformation-resistance pipeline steels of the present invention use following process route：Stock → converter or electric furnace smelting → external refining → casting → slab reheating → controlled rolling → control cooling.

Its TMCP technological temperature and cooling rate are controlled according to following parameter：1050-1250 DEG C of slab heating temperature；It ties again 950-1150 DEG C of crystalline region controlled rolling start temperature, 900-1100 DEG C of recrystallization zone controlled rolling final temperature；Noncrystalline domain control System 800-900 DEG C of start temperature of rolling, 750-800 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool temperature 680-780 DEG C of degree, section cooling terminate 450-550 DEG C of cooling temperature, section cooling cooling velocity：5-25℃/s.

Its TMCP techniques reduction in pass is controlled with accumulation drafts according to following parameter：Recrystallization zone rolling is completed Workpiece thickness (3.1-3.9) t afterwards；When recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass becomes Shape amount is adjusted according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.8t or when less than 6.2t, single pass deformation Measure 10%-14%；When steel billet exit thickness is less than 7.8t and is more than or equal to 6.2t, single pass heavy deformation 16%-24%；It is non-again Crystal region cumulative deformation is not less than 65%.

Technological parameter used by its TMCP stage, based on the recognition that：

Slab heating temperature：For continuous casting billet through reheating again, original coarse as cast condition dendrite is real through reaustenitizing Existing homogenization of composition and crystal grain refinement provide necessary tissue preparation and temperature preparation to roll state.Austenite becomes with high-ductility Shape ability, temperature is higher, and its mobility is better, but the excessively high Austenite Grain Growth tendency of temperature becomes larger.Temperature is too low, Ovshinsky Body resistance of deformation becomes larger, and the pass deformation in the stage is restricted, in order to reach good austenitizing effect, plate of the present invention Base heating temperature range is designed as 1050-1250 DEG C.

Recrystallization zone controlled rolling temperature and deflection：Recrystallization zone controlled rolling is to utilize Austenite Dynamic Recrystallization and static state again The characteristic of crystallization makes the Austenite Grain Refinement after coarse heating of plate blank.In order to realize that austenitizing recrystallizes, temperature is certain In the case of, there are minimum values for pass deformation, are based on this, which is the bigger the better, but due to milling train The problems such as ability, billet bloom size are matched with final steel plate gauge lattice, single pass heavy deformation again cannot be arbitrarily devised.In addition, temperature is high, The single pass least amount of deformation occurred needed for recrystallization is also small, but the crystal grain coarsening rate after recrystallizing at this time is also fast；Temperature Low, crystal grain coarsening rate is small, but required single pass least amount of deformation is consequently increased；Temperature is as low as to a certain degree, just Recrystallization will not occur again, the effect of recrystallization softening crystal grain is also just lost to austenite deformation.In this stage, become when total Shape amount is more than to recrystallize to the thinning effect of crystal grain with regard to unobvious after 60%.Therefore, recrystallization stage control of the invention Roll 950-1150 DEG C of start temperature, 900-1100 DEG C of final temperature；Single pass heavy deformation is selected as according to steel billet exit thickness 10%-14% or 16%-20% and total deformation 45%-65%.

Non- recrystallization zone controlled rolling temperature and deflection：Non- recrystallization rolling needs to consider to avoid in temperature upper limit design Incomplete recrystallization section adversely affects the uniformity and low-temperature flexibility of plate property in order to avoid generating mixed grain structure.It is non- Recrystallization rolling adds up effect because deformation exists, and the resistance of deformation of crystal grain increases with the increase of deflection, with deformation The reduction of temperature and increase, therefore, the temperature of the stage rolling cannot be too low, without pay special attention to single pass heavy deformation, only Ensure that entire steel plate thickness direction can be deformed.Therefore, noncrystalline stage control of the invention rolling starts temperature 800-900 DEG C of degree, 750-800 DEG C of final temperature；Accumulative deflection is not less than 65%.

Section cooling temperature range and cooling velocity：Since it is desired that subsequent heat treatment, the start temperature of section cooling is got over It is high better, but need to make reasonable arrangement to match rhythm of production；The finishing temperature of section cooling is too low, is unfavorable for plate shape Control, the excessive subsequent heat treatment back plate shape of internal stress is necessarily bad, if section cooling temperature is excessively high, the austenite not changed is just Pearlite or coarse MA constituent elements can be changed into, this kind of richness carbon phase is unfavorable for the homogenization of composition in follow-up heat treatment process and group Knit the Uniform Control.It is heated in two-phase section, because structural transformation is needed to realize the long-range diffusion of C and be reallocated, if rich carbon phase It is excessive or oversized, it is necessarily required to extend heating time or heating temperature, it is coarse to easily cause excessive grain, to obdurability With unfavorable.For cooling velocity, high cooling rate is conducive to crystal grain refinement, but also brings along high residual stress, is unfavorable for plate Shape controls.In addition, steel plate, under high cooling rate, the structural homogenity on thickness direction is also undesirable.Therefore, the present invention chooses 680-780 DEG C of section cooling start temperature, 450-550 DEG C of final temperature, cooling velocity are 5-25 DEG C/s.

Tiny TMCP tissues are conducive to the Dispersed precipitate of cenotype when heat treatment, and parent grain is tiny, the crystal grain of cenotype It is corresponding smaller；Low steel plate residual stress and wall thickness direction even tissue, the control to the stability contorting and plate shape of plate property It is advantageous.

After the completion of TMCP states Plate Production of the present invention, two-phase section quenching is carried out, which is characterized in that this method includes following step Suddenly：Steel is heated in heat-treatment furnace to 650-750 DEG C, soaking time is { t ± 5 (1.3-1.8) } minute, then uses quenching press Water quenching is organized to room temperature, 21-45 DEG C of cooling velocity/s.

After the completion of two-phase section quenching, tempering may be used or do not use tempering process；Temperature is 150-450 DEG C, when When temperature is 150-200 DEG C, tempering time is { t ± 5 (1.2-1.4) } minute；When temperature is more than 200 DEG C and is less than At 305 DEG C, tempering time is selected as { t ± 5 (0.9-1.1) } minute；When temperature is 305-450 DEG C, tempering time is { t ± 5 (0.6-0.8) } minute.

Technological parameter used by heat treatment stages, based on the recognition that：Two-phase section heats, and statenchyma is polygon Ferrite+austenite, with the raising of temperature, austenite volume fraction increases；With the extension of soaking time, new phase volume point Number gradually increases, but not more than the volume fraction of its equilibrium state, if being further added by soaking time at this time, the Main change of cenotype Show as crystallite dimension increase；Heating temperature selects between Ac1-Ac3, and when the ingredient of steel determines, the temperature range is also just true It is fixed.It improves heating temperature, extend soaking time, ferrite volume fraction just will increase, while ferrite grain size also can It grows up；Low soaking time, low holding temperature will necessarily reduce production cost, however, to ensure that ferritic amount of precipitation, Certainly exist a lower limiting value.In addition, it is also to reduce a selection of soaking time to properly increase holding temperature.After the completion of heating Water quenching process, high cooling rate can bring fine grain structure, but for steel plate, cooling rate is excessively high, entire steel plate thickness direction Structural homogenity is undesirable, in addition, excessively tiny ferrite crystal grain, is also unfavorable for the raising of uniform elongation.Therefore, this hair Bright two-phase section heating temperature is 650-750 DEG C, and the time is { t ± 5 (1.3-1.8) } minute, 21-45 DEG C of water quenching cooling rate/s.

Temperature and soaking time：After two-phase section quenching, in order to eliminate steel plate internal stress and promote the solid solutions such as N, O, C The diffusion and precipitation of the small atom of state act on the anchoring of dislocation after reducing tubulation in hot coating procedure, reduce timeliness to steel plate system The adverse effect of performance after pipe can selectively carry out temper.Temperature is referred to the heat coating work after tubulation Skill temperature selects, but in order to realize preferably tempering effect, soaking time is reduced while properly increasing temperature, is equally had Positive effect.Therefore, present invention selection is tempered at 150-450 DEG C, when temperature is 150-200 DEG C, tempering time For { t ± 5 (1.2-1.4) } minute；When temperature is more than 200 DEG C and is less than 305 DEG C, tempering time is selected as { (0.9- 1.1) t ± 5 } minute；When temperature is 305-450 DEG C, tempering time is { t ± 5 (0.6-0.8) } minute.

Heat treatment state large-deformation-resistance pipeline steel of the present invention, compared with existing TMCP states large-deformation-resistance pipeline steel, tool Having lower yield tensile ratio, uniform elongation higher, obdurability to match, more preferable, steel plate is small with plate poor performance, thickness direction even tissue Property the high, advantages such as band-like rank is low, be suitable for the production based on stress design area Longitudinal SAW Pipe.

In the present invention, steel plate is heated in two-phase section, and due to ferritic formation, rich carbon can occur for surrounding parent phase tissue, from And increase parent phase tissue stability to improve low-alloy steel quenching degree.The phases such as quenched ferritic phase and bainite, the two Between difference of hardness, intensity difference bigger, the property of resisting large deformation (uniform elongation, yield tensile ratio and stress ratio) of steel plate, compared with TMCP works The two-phase Steel Properties of skill production are more excellent.Because using two-phase section quenching, quenching is cooling compared with section cooling higher, and cooling effect is more Uniformly, steel plate even tissue, performance is small with plate difference, banded structure rank is low.

Any mixture of finally obtained ferrite+bainite/martensite/MA constituent elements or three after present invention heat treatment The soft or hard steel plate for mixing tissue constituted, horizontal mechanical performance can reach following requirement：Yield strength Rt0.5 is 550- 700MPa, tensile strength Rm are 640-830MPa, yield tensile ratio Rt0.5/Rm≤0.75, and -20 DEG C of impact absorbings can be more than 200J, - 20 DEG C of DWTT sections of shear SA are not less than 85%.The vertical mixing coefficient of steel plate can reach following requirement：Homogeneous deformation extends Rate UEL>14%, yield strength Rt0.5 be 480-600MPa, tensile strength Rm be 570-750MPa, yield tensile ratio Rt0.5/Rm≤ 0.75, stress-strain diagram without yield point elongation and Rt1.5/Rt0.5 not less than 1.17, Rt2.0/Rt1.0 not less than 1.07, Rt5.0/Rt1.0 is not less than 1.11, wherein Rt1.0, Rt1.5, Rt2.0, Rt5.0 be total elongation be 1.0%, 1.5%, 2.0%, the stress value corresponding to 5.0%.

Specific implementation mode

A kind of X80 large-deformation-resistance pipelines steel of the present invention, the mass percent of chemical composition is C 0.04%- in the steel 0.09%, Si 0.15%-0.55%, Mn 1.50%-1.75%, Nb 0.04%-0.10%, V 0.02%-0.08%, Ti 0.01%-0.03%, Cu 0.15%-0.55%, Ni 0.15-0.55%, Cr 0-0.15%, Mo 0.15%-0.45%, Al 0.025%-0.045%, N 0.0002%-0.011%, P≤0.015%, S≤0.005%, remaining is Fe and other for can not The impurity element avoided.

The destination organization of moderate resistance large deformation Pipeline Steel Plate of the present invention is by apparent two phase composition of nonhomogeneous hardness, wherein soft phase is Ferrite, including polygonal ferrite, quasi-polygonal ferrite or their any mixture；Hard is mutually bainite, MA groups Member, martensite or their any mixture；Ferritic volume fraction is 40%-60%；Ferrite crystal grain average diameter is 4-10um。

A kind of TMCP rolled Plate Productions in the present invention used in X80 large-deformation-resistance pipelines steel use following technique road Line：Stock → converter or electric furnace smelting → external refining → casting → slab reheating → controlled rolling → control cooling.

Its TMCP technological temperature and cooling rate are controlled according to following parameter：1050-1250 DEG C of slab heating temperature；It ties again 950-1150 DEG C of crystalline region controlled rolling start temperature, 900-1100 DEG C of recrystallization zone controlled rolling final temperature；Noncrystalline domain control System 800-900 DEG C of start temperature of rolling, 750-800 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool temperature 680-780 DEG C of degree, section cooling terminate 450-550 DEG C of cooling temperature, section cooling cooling velocity：5-25℃/s.

Its TMCP techniques reduction in pass is controlled with accumulation drafts according to following parameter：Recrystallization zone rolling is completed Workpiece thickness (3.1-3.9) t afterwards；When recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass becomes Shape amount is adjusted according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.8t or when less than 6.2t, single pass deformation Measure 10%-14%；When steel billet exit thickness is less than 7.8t and is more than or equal to 6.2t, single pass heavy deformation 16%-24%；It is non-again Crystal region cumulative deformation is not less than 65%.

After the completion of above-mentioned TMCP states Plate Production, two-phase section quenching is carried out, which is characterized in that this method includes following step Suddenly：Steel is heated in heat-treatment furnace to 650-750 DEG C, soaking time is { t ± 5 (1.3-1.8) } minute, then uses quenching press Water quenching is organized to room temperature, 21-45 DEG C of cooling velocity/s.

After the completion of two-phase section quenching, 150-450 DEG C of tempering is carried out, tempering process is selectable heat treatment procedure, can be with It does not use.When tempering, when temperature is 150-200 DEG C, tempering time is { t ± 5 (1.2-1.4) } minute；When tempering temperature When degree is 305-450 DEG C, tempering time is { t ± 5 (0.6-0.8) } minute；When temperature is more than 200 DEG C and is less than 305 DEG C When, tempering time is selected as { t ± 5 (0.9-1.1) } minute.

It elaborates to the present invention below by one group of most preferred embodiment of the present invention：

Chemical composition, technological parameter and the results of property of embodiment 1-20 is as shown in tables 1 to 5.

1 chemical composition of table (wt%)

2 TMCP technological parameters of table

Table 3 is heat-treated (two-phase section quenching+tempering) technological parameter after rolling

Note：In table " " represent do not carry out tempering heat treatment.

4 horizontal mechanical performance result of table

5 vertical mixing coefficient result of table

Claims (2)

1. a kind of preparation method of X80 large-deformation-resistance pipeline steels, which is characterized in that the change of the X80 large-deformation-resistance pipeline steels It is C 0.04%-0.09%, Si 0.15%-0.55%, Mn 1.50%-1.75%, Nb to learn composition quality percentage 0.04%-0.10%, V 0.02%-0.08%, Ti 0.01%-0.03%, Cu 0.15%-0.55%, Ni 0.15- 0.55%, Cr 0-0.15%, Mo 0.15%-0.45%, Al 0.025%-0.045%, N 0.0002%-0.011%, P≤ 0.015%, S≤0.005%, remaining be Fe and it is other be inevitable impurity element, steel plate thickness target be 26.4mm and More than it, the TMCP rolled steel plates produced on cut deal reciprocating rolling mill using 230mm-300mm thickness steel billet,

It, which is produced, uses following process route：Stock → converter or electric furnace smelting → external refining → casting → slab reheats → Controlled rolling → control cooling；

Its TMCP technological temperature and cooling rate are controlled according to following parameter：1050-1250 DEG C of slab heating temperature；Recrystallization zone 950-1150 DEG C of controlled rolling start temperature, 900-1100 DEG C of recrystallization zone controlled rolling final temperature；Noncrystalline domain control is rolled 800-900 DEG C of start temperature processed, 750-800 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool temperature 680-780 DEG C, section cooling terminates 450-550 DEG C of cooling temperature, 5-25 DEG C of section cooling cooling velocity/s；

Its TMCP techniques reduction in pass is controlled with accumulation drafts according to following parameter：In after the completion of recrystallization zone rolling Between base thickness (3.1-3.9) t；When recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass heavy deformation It is adjusted according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.8t or when less than 6.2t, single pass heavy deformation 10%-14%；When steel billet exit thickness is less than 7.8t and is more than or equal to 6.2t, single pass heavy deformation 16%-24%；It is non-to tie again Crystalline region cumulative deformation is not less than 65%；

After the completion of above-mentioned TMCP states Plate Production, two-phase section quenching is carried out, quenching includes the following steps：It is heated in heat-treatment furnace For steel to 650-750 DEG C, soaking time is { t ± 5 (1.3-1.8) } minute, then using quenching unit water quenching to room temperature, cooling speed Spend 21-45 DEG C/s；

After the completion of quenching, tempering is not used or carries out 150-450 DEG C of tempering；When using tempering process, when temperature is At 150-200 DEG C, tempering time is { t ± 5 (1.2-1.4) } minute；When temperature is more than 200 DEG C and is less than 305 DEG C, return Fiery selection of time is { t ± 5 (0.9-1.1) } minute；When temperature is 305-450 DEG C, tempering time is { (0.6-0.8) t ± 5 } minute；

T is steel plate thickness, unit (mm) in formula.

2. a kind of preparation method of X80 large-deformation-resistance pipeline steels according to claim 1, which is characterized in that the X80 Large-deformation-resistance pipeline is that ferrite and hard phase bainite, MA constituent elements, martensite form by soft phase with structure of steel, wherein ferritic Volume fraction is 40%-60%；Ferrite crystal grain average diameter is 4-10um.