CN106319390B - X70 large deformation resistant pipeline steel and manufacturing method thereof - Google Patents
X70 large deformation resistant pipeline steel and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses X70 anti-large deformation pipeline steel and a manufacturing method thereof, wherein the steel comprises, by mass, 0.04% -0.09% of C, 0.15% -0.55% of Si, 1.45% -1.75% of Mn, 0.04% -0.10% of Nb, 0.02% -0.08% of V, 0.01% -0.03% of Ti, 0% -0.20% of Cu, 0.15-0.55% of Ni, 0-0.15% of Mo, 0.15% -0.45% of Cr, 0.025% -0.045% of Al, 0.0002% -0.011% of N, less than or equal to 0.015% of P, less than or equal to 0.005% of S, and the balance Fe and other inevitable impurity elements. The production adopts the following process route: the method comprises the steps of material preparation → converter or electric furnace smelting → external refining → casting → slab reheating → controlled rolling → controlled cooling, tempering after two-phase zone quenching or not adopting a tempering process.
Description
Technical field
The invention belongs to technical field of pipeline steel, is related to a kind of X70 large-deformation-resistance pipeline steels and manufacture method, especially relates to
A kind of and X70 large-deformation-resistance pipeline Wide and Thick Slabs prepared using two-phase section process for quenching and preparation method thereof.Using the present invention
The pipeline Wide and Thick Slab of preparation, it can apply 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 is thole top-type.In order to quantify the ess-strain of thole top-type song
Line, refer 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 the advantages that measurement is easy, and description curve shape is more accurate relative to n.
In order to reach based on the property of resisting large deformation needed for stress design, there are two kinds of means：1) thick walled steel tube is used；2) adopt
With the Plate Production steel pipe of duplex structure.In actual application, both approaches are not isolated.If only with increase wall
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.
At present, the large deformation Pipeline Steel Plate of heavy wall two-phase is produced, there are two kinds of process routes, first, rolled after controlled rolling and controlled cooling
The supply of material, a kind of reused after the steel plate after controlled rolling and controlled cooling is heat-treated.Because steel plate wall thickness is big, traditional TMCP techniques
The dual phase sheet steel of production, exist in performance with the shortcoming such as plate difference is big, low temperature DWTT properties percent of pass is low, organizationally exist
The deficiencies of banding rank is high, along wall thickness direction uneven microstructure.
In order to overcome these technological deficiencies, heat treatment step can be increased on the basis of TMCP techniques.At present, using heat
The open source literature of processing mode production large deformation pipe line steel is still rare.Patent CN201110054270.7 discloses " one kind tool
Have the large-deformation-resistance pipeline steel and its production method of excellent aging resistance ", its steel plate roll rear water cooling speed it is low, terminate chilling temperature
Height is also easy to produce thick MA, unfavorable to subsequent heat treatment technology controlling and process；Patent CN201010266539.3 discloses " one kind heat treatment
Large-deformation-resistance pipeline steel prepared by method and preparation method thereof ", its 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 that thickness of thin only has 1.7-2.0 times of finished steel plate and rolled final cooling temperature height is also easy to produce thick 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 ", the patent is not intended to produce large-deformation-resistance pipeline steel, and its grade of steel is only X65.
In summary, existing low temperature DWTT poor performances, banded structure rank for X70 level large-deformation resistance pipe line steels
The subject matters such as height, thickness of slab direction uneven microstructure.
The content of the invention
It is an object of the invention to provide a kind of X70 large-deformation-resistance pipeline steels and preparation method thereof, to solve current TMCP works
It is existing with weak points such as big, the banded structure rank height of plate difference performance difference during skill production large-deformation-resistance pipeline steel, together
When further to produce thickness specification higher based on stress design area Wide and Thick Slab, to meet X70 and above rank is anti-big becomes
The requirement of Wide and Thick Slab used in shape pipe line steel.
Present invention employs the two-phase section quenching technology for being more beneficial for improving steel plate property of resisting large deformation, the technology has
The advantages that cooling velocity is higher, the control of steel plate tissue ratio is accurate.Add after thinking about it quenching process, although multiple in process
It is miscellaneous some, but the structural homogenity of steel plate, properties percent of pass and stability are increased substantially, and particularly thickness is exceeded
The 25mm steel plate for anti-large deformation, the cost performance for being heat-treated production are substantially better than the cost performance of TMCP productions.
Finished steel plate thickness is represented with t (unit, mm) in the present invention.
The purpose of the present invention is achieved through the following technical solutions：
X70 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 1.45%-1.75%, Nb 0.04%-0.10%, V 0.02%-
0.08%, Ti 0.01%-0.03%, Cu 0%-0.20%, Ni 0.15-0.55%, Mo 0-0.15%, Cr 0.15%-
0.45%, Al 0.025%-0.045%, N 0.0002%-0.011%, P≤0.015%, S≤0.005%, remaining be Fe and
Other is inevitable impurity element.
The destination organization of moderate resistance large deformation Pipeline Steel Plate of the present invention is by obvious 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 35%-65%；Ferrite crystal grain average diameter is
3-11um。
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；Appropriate soft or hard Phase Proportion, it is possible to achieve intensity, low temperature
Toughness, the matched well of property of resisting large deformation, so as to meet the whole requirement based on stress design pipe line steel.Ferrite
When fraction is identical, increase ferrite grain size, be advantageous to improve uniformly extension numerical value and reduction yield tensile ratio；Ferrite crystal grain mistake
In thick, the low-temperature flexibility of steel plate can be adversely affected.Therefore, the ferrite volume fraction that the present invention chooses is 35-65%,
Ferrite average diameter is 3-11um.
The effect of main constituents is as follows in steel of the present invention：
C：Most economical in steel, most basic intensified element, the strong of steel can be significantly improved 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, it is impossible to give full play to the precipitation enhancement of the elements such as Nb.Therefore it is of the invention by C
Content range is set as 0.04%-0.09%.
Si：Adding Si is for intensity of the deoxidation with improving matrix in steelmaking process, and Si, which also has, suppresses what cementite was formed
Effect.If the toughness of the Si of excessive addition, mother metal 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 of 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
Contribute 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 that ferrite is separated out with growing up in lower temperature.Mn content, the quenching degree increase of steel are improved, 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, too high Mn contains
Amount can also increase continuous casting billet center segregation, make the anisotropy of plate property increase.In order between proof strength and low-temperature flexibility
Balance and higher slab quality, Mn content ranges of the invention be designed as 1.45%-1.75%.
Nb：It is one of most important micro alloying element in modern pipe line steel, the effect to crystal grain refinement is fairly obvious.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
It is organized in the deformed austeaite of non-recrystallization zone rolling and is changed into tiny phase-change product during phase transformation, so that steel has high intensity
And high tenacity.The present invention is exactly to coordinate C content to add the effect that appropriate Nb plays NbC, Nb content ranges 0.04%-0.10%.
V：Combined with C in steel or N, there is very strong precipitation strength to act on.Compared with Nb, carbonitride dissolving-analysis containing V
Go out that equilibrium temperature is low, be advantageous under relatively low heating temperature condition that back dissolving is with separating out, so as to play anchoring crystal boundary crystal grain thinning
Effect.Heated in two-phase section, Nb, Ti carbonitride are unable to back dissolving, and have the tendency of to grow up, and V with back dissolving because can not deposited
In this problem, thus be more suitable for two-phase section heating use with realize crystal grain refinement, precipitation strength etc. effect.Excessive V is to even
Casting process is unfavorable, therefore the V content scope 0.02%-0.08% that the present invention chooses.
Ti：It is strong solid N element, Ti/N stoichiometric proportion is 3.42, and steel can be fixed using 0.01% or so Ti
Middle 30ppm or so N, the TiN precipitated phases of tiny high-temperature stable can be formed in sheet billet continuous casting.This tiny TiN particles
Austenite Grain Growth when slab reheats can effectively be suppressed, the solid solubility of Nb, V in austenite is favorably improved, changes
The impact flexibility of kind welding heat affected zone.When Als content is too low (as being less than 0.005%), Ti can form oxide, in these
Raw particle can play a part 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 additions exceed certain certain value, TiN particles will be roughened, TiC precipitation enhancement
Show, cause low-temperature flexibility to deteriorate.Therefore, the present invention chooses Ti content ranges 0.01%-0.03%.
Al：Al presence also plays the role of thinning microstructure typically as the deoxidier in steel.But when Al content
Excessively, the amount of aluminum oxide nonmetal inclusion increases so as 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 Al content range 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
Adding mainly improves Cu caused red brittleness in steel, and Ni is also beneficial to low-temperature flexibility in itself.In think gauge pipe line steel
Can also compensate for because of caused by the increase of thickness water cooling intensity deficiency and caused by intensity decline.The present invention chooses Cu 0%-
0.20%th, Ni 0.15%-0.55%.
Cr、Mo：Cr, Mo element are added, CCT curve can be moved to right, the stability increase of austenite, so as to promote bayesian
Body phase becomes, and 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 advantageous to the improvement of low-temperature flexibility.During heat treatment step, suitably
Cr, Mo content, it is possible to achieve the optimization of heat treatment heating-up temperature and soaking time.In order to obtain intensity, plasticity and toughness
Reasonably combined, the present invention chooses Mo 0-0.15%, Cr 0.15%-0.45%.
N：N is one of inevitable impurity element in steel, and content is unsuitable too high, but N and Al, Ti, Nb, V etc. are nitrogenized
Thing formation element chemical combination, can play a part 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 low better.For smelting cost and production technology
Limitation, again can not 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 carries out inclusion morphology control to sulfide, can make the low-temperature flexibility of raising pipe line steel.
The present invention has the feature of low manganese plus vanadium.Manganese is low, and transformation temperature is low, and ferrite can separate out more in relatively low temperature
More amounts, ferritic size are also more tiny.
A kind of X70 large-deformation-resistance pipeline steels of the present invention are that thickness targets are 26.4mm and its above, steel plate use 230mm-
The TMCP rolled steel plates that 300mm thickness steel billet is produced on cut deal reciprocating rolling mill.
TMCP rolleds steel plate used in a kind of X70 large-deformation-resistance pipeline steels of the present invention uses 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；Tie 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 830-900 DEG C of start temperature of rolling, 805-850 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool down temperature
785-835 DEG C of degree, section cooling terminate 450-550 DEG C of chilling 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 (3.0-4.0) t afterwards；During recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass becomes
Shape amount adjusts according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.5t or during less than 5.9t, single pass deformation
Measure 10%-14%；When steel billet exit thickness is less than 7.5t and is more than or equal to 5.9t, 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 thick as cast condition dendrite is real through reaustenitizing
Existing homogenization of composition and crystal grain refinement, necessary tissue preparation and temperature preparation are provided to roll state.Austenite has high-ductility change
Shape ability, temperature is higher, and its mobility is better, but the too high Austenite Grain Growth tendency of temperature becomes big.Temperature is too low, Ovshinsky
Body resistance of deformation becomes big, 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, it is to utilize Austenite Dynamic Recrystallization and static state again
The characteristic of crystallization, make the Austenite Grain Refinement after thick heating of plate blank.In order to realize that austenitizing recrystallizes, temperature is certain
In the case of, there is minimum value in pass deformation, based on this, the stage single pass heavy deformation is the bigger the better, but due to milling train
The problems such as ability, billet bloom size match with final steel plate gauge lattice, single pass heavy deformation again can not 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 now recrystallizing is also fast；Temperature
Low, crystal grain coarsening rate is small, but required single pass least amount of deformation is consequently increased；Temperature is low to a certain extent, 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
After shape amount is more than 60%, recrystallize to the thinning effect of crystal grain with regard to unobvious.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 selects 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, it is necessary to consider to avoid in temperature upper limit design
Incomplete recrystallization section, in order to avoid producing mixed grain structure, the uniformity and low-temperature flexibility of plate property are adversely affected.It is non-
Recrystallization rolling is because accumulative effect be present in deformation, 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 can not be too low, without pay special attention to single pass heavy deformation, only
Ensure that whole steel plate thickness direction can be deformed.Therefore, noncrystalline stage control of the invention rolling starts temperature
830-900 DEG C of degree, 805-850 DEG C of final temperature；Accumulative deflection is not less than 65%.
Section cooling temperature range and cooling velocity：Since it is desired that follow-up 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, plate shape is necessarily bad after the excessive subsequent heat treatment of internal stress, if section cooling temperature is too high, the austenite not changed is just
Pearlite or thick MA constituent elements can be changed into, this kind of rich carbon phase is unfavorable for homogenization of composition and group in follow-up heat treatment process
Knit the Uniform Control.Heated in two-phase section, because structural transformation needs to realize C long-range diffusion and reallocation, if rich carbon phase
It is excessive or oversized, it is necessarily required to extend heat time or heating-up temperature, easily causes excessive grain thick, to obdurability
With unfavorable.For cooling velocity, high cooling rate is advantageous 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
785-835 DEG C of section cooling start temperature, 450-550 DEG C of final temperature, cooling velocity be 5-25 DEG C/s.
Tiny TMCP tissues are advantageous to the Dispersed precipitate of cenotype during 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 of stability contorting and plate shape to plate property
It is favourable.
After the completion of TMCP states Plate Production of the present invention, two-phase section quenching is carried out, it is characterised in that this method includes following step
Suddenly：Steel is heated in heat-treatment furnace to 685-795 DEG C, soaking time is { (1.1-2.0) t ± 5 } minute, then using quenching press
Water quenching is organized to room temperature, 16-45 DEG C of cooling velocity/s.
The present invention is quenched by two-phase section, and steel plate is rolled into state tissue, in two-phase section temperature range inside holding for a period of time,
The two-phase structure that ferrite and austenite are formed is changed into, by subsequent quenching, is transformed into ferrite+hard phase of room temperature state
Tissue.Wherein ferrite includes polygonal ferrite, quasi-polygonal ferrite or their any mixture；Hard phase body is bayesian
Body, MA constituent elements, martensite, or their any mixture.
After the completion of two-phase section quenching, 150-450 DEG C of tempering is carried out, tempering process is selectable heat treatment step, can be with
Do not use.During tempering, when temperature is 150-195 DEG C, tempering time is { (1.2-1.4) t ± 5 } minute；When tempering temperature
When degree is more than 195 DEG C and is less than 305 DEG C, tempering time selection is { (0.9-1.1) t ± 5 } minute；When temperature is 305-
At 450 DEG C, tempering time is { (0.6-0.8) t ± 5 } minute.
Technological parameter used by heat treatment stages, based on the recognition that：Two-phase section heats, and its statenchyma is polygon
Ferrite+austenite, with the rise of temperature, austenite volume fraction increases；With the extension of soaking time, cenotype volume integral
Number gradually increases, but not more than the volume fraction of its poised state, if being now further added by soaking time, the Main change of cenotype
Show as crystallite dimension increase；Heating-up temperature is selected between Ac1-Ac3, and when the composition of steel determines, the temperature range is also just true
It is fixed.Improve heating-up temperature, extend soaking time, ferrite volume fraction will increase, while ferrite grain size also can
Grow up；Low soaking time, low holding temperature will necessarily reduce production cost, however, to ensure that ferritic amount of precipitation,
Certainly exist a lower limit.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 too high, whole 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-up temperature is 685-795 DEG C, and the time is { (1.0-2.0) ± 5 } minute, 16-45 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 solution such as N, O, C
The diffusion and precipitation of the small atom of state, the anchoring of dislocation is acted in hot coating procedure after reducing tubulation, reduce timeliness to steel plate system
The adverse effect of performance after pipe, it 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 150-195 DEG C, tempering time
For { (1.2-1.4) t ± 5 } minute；When temperature is 305-450 DEG C, tempering time is { (0.6-0.8) t ± 5 } minute；
When temperature is more than 195 DEG C and is less than 305 DEG C, tempering time selection is { (0.9-1.1) t ± 5 } minute.
Heat treatment state large-deformation-resistance pipeline steel of the present invention, compared with existing TMCP states large-deformation-resistance pipeline steel, tool
Have that yield tensile ratio is lower, uniform elongation is higher, obdurability matching is more preferable, steel plate is the same as plate poor performance is small, thickness direction even tissue
Property the high, advantage such as banding rank is low, suitable for the production based on stress design area Longitudinal SAW Pipe.
In the present invention, steel plate heats 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 so as to improve low-alloy steel quenching degree.The phases such as ferritic phase after quenching and bainite, both
Between difference of hardness, intensity difference it is 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 employing two-phase section quenching, quenching cools down, cooling effect higher compared with section cooling
Evenly, steel plate even tissue, performance is the same as plate difference is small, banded structure rank is low.
Ferrite+bainite/martensite/MA the constituent elements or any mixture of three finally given after present invention heat treatment
The soft or hard steel plate for mixing tissue formed, its horizontal mechanical performance can reach following requirement：Yield strength Rt0.5 is 485-
630MPa, tensile strength Rm are 570-760MPa, yield tensile ratio Rt0.5/Rm≤0.73, 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>16%, yield strength Rt0.5 are 400-550MPa, and tensile strength Rm is 550-700MPa, yield tensile ratio Rt0.5/Rm≤
0.70, stress-strain diagram without yield point elongation and Rt1.5/Rt0.5 not less than 1.19, Rt2.0/Rt1.0 not less than 1.08,
Rt5.0/Rt1.0 is not less than 1.12, wherein Rt1.0, Rt1.5, Rt2.0, Rt5.0 be total elongation be 1.0%, 1.5%,
2.0%th, the stress value corresponding to 5.0%.
Embodiment
A kind of X70 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 1.45%-1.75%, Nb 0.04%-0.10%, V 0.02%-0.08%, Ti
0.01%-0.03%, Cu 0%-0.20%, Ni 0.15-0.55%, Mo 0-0.15%, Cr 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.
A kind of TMCP rolleds Plate Production in the present invention used in X70 large-deformation-resistance pipelines steel uses 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；Tie 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 830-900 DEG C of start temperature of rolling, 805-850 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool down temperature
785-835 DEG C of degree, section cooling terminate 450-550 DEG C of chilling 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 (3.0-4.0) t afterwards；During recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass becomes
Shape amount adjusts according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.5t or during less than 5.9t, single pass deformation
Measure 10%-14%；When steel billet exit thickness is less than 7.5t and is more than or equal to 5.9t, 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, it is characterised in that this method includes following step
Suddenly：Steel is heated in heat-treatment furnace to 685-795 DEG C, soaking time is { (1.1-2.0) t ± 5 } minute, then using quenching press
Water quenching is organized to room temperature, 16-45 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 step, can be with
Do not use.During tempering, when temperature is 150-195 DEG C, tempering time is { (1.2-1.4) t ± 5 } minute；When tempering temperature
Spend for 305-450 DEG C when, tempering time is { (0.6-0.8) t ± 5 } minute；When temperature is more than 195 DEG C and less than 305 DEG C
When, tempering time selection is { (0.9-1.1) t ± 5 } minute.
The present invention is elaborated below by one group of most preferred embodiment of the present invention：
Embodiment 1-20 chemical composition, technological parameter and results of property is as shown in tables 1 to 5.
The chemical composition of table 1 (wt%)
The TMCP technological parameters of table 2
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.
The horizontal mechanical performance result of table 4
The vertical mixing coefficient result of table 5
Claims (3)
- A kind of 1. preparation method of X70 large-deformation-resistance pipeline steels, it is characterised in that the change of described X70 large-deformation-resistance pipeline steels It is C 0.04%-0.09%, Si 0.15%-0.55%, Mn 1.45%-1.75%, Nb to learn composition quality percentage 0.04%-0.10%, V 0.02%-0.08%, Ti 0.01%-0.03%, Cu 0%-0.20%, Ni 0.15-0.55%, Mo 0-0.15%, Cr 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, thickness targets be 26.4mm and its with On, steel plate is the TMCP rolled steel plates that are produced on cut deal reciprocating rolling mill using 230-300mm 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 830-900 DEG C of start temperature processed, 805-850 DEG C of noncrystalline domain controlled rolling final temperature；Section cooling begins to cool down temperature 785-835 DEG C, section cooling terminates 450-550 DEG C of chilling temperature, section cooling, cooling velocity：5-25℃/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 (3.0-4.0) t；During recrystallization zone stage rolling, recrystallization zone total deformation 45%-65%；Single pass heavy deformation Adjusted according to steel billet exit thickness, when steel billet exit thickness is more than or equal to 7.5t or during less than 5.9t, single pass heavy deformation 10%-14%；When steel billet exit thickness is less than 7.5t and is more than or equal to 5.9t, 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 comprises the following steps：Heated in heat-treatment furnace For steel to 685-795 DEG C, soaking time is { (1.1-2.0) t ± 5 } minute, then using quenching unit water quenching to room temperature, cooling speed Spend 16-45 DEG C/s；T is finished steel plate thickness in formula, unit mm.
- A kind of 2. preparation method of X70 large-deformation-resistance pipeline steels according to claim 1, it is characterised in that：Described X70 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 35%-65%；Ferrite crystal grain average diameter is 3-11um.
- 3. the preparation method of a kind of X70 large-deformation-resistance pipeline steels according to claim 1, it is characterised in that quenching is completed Afterwards, do not use tempering or carry out 150-450 DEG C of tempering；During using tempering process, when temperature is 150-195 DEG C, return The fiery time is { (1.2-1.4) t ± 5 } minute；When temperature is 305-450 DEG C, tempering time is { (0.6-0.8) t ± 5 } Minute；When temperature is more than 195 DEG C and is less than 305 DEG C, tempering time selection is { (0.9-1.1) t ± 5 } minute；T is finished steel plate thickness in formula, unit mm.
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| CN109957710B (en) * | 2017-12-14 | 2020-07-17 | 鞍钢股份有限公司 | V-containing large-deformation X80M pipeline steel plate and manufacturing method thereof |
| CN109957709B (en) * | 2017-12-14 | 2020-07-17 | 鞍钢股份有限公司 | V-containing large-deformation X70M pipeline steel plate and manufacturing method thereof |
| CN110616383B (en) * | 2018-06-20 | 2021-03-12 | 宝山钢铁股份有限公司 | Pipeline steel with excellent toughness for-45 ℃ extremely-low temperature environment and manufacturing method thereof |
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| CN111154963A (en) * | 2019-12-26 | 2020-05-15 | 钢铁研究总院 | Welding heat influence region-resistant softened submarine pipeline steel and preparation method thereof |
| CN111826507B (en) * | 2020-06-19 | 2021-12-03 | 华菱安赛乐米塔尔汽车板有限公司 | Production process of steel with ultrahigh yield ratio |
| CN113930685B (en) * | 2021-10-13 | 2022-08-16 | 鞍钢股份有限公司 | 700 MPa-grade high-plasticity-transformation precipitation strengthening pipeline steel plate and production method thereof |
| CN114892081B (en) * | 2022-04-28 | 2023-07-28 | 湖南华菱湘潭钢铁有限公司 | High-thickness 460 MPa-level steel plate with excellent low-temperature toughness for ocean engineering and production method thereof |
| CN115181907B (en) * | 2022-07-06 | 2023-05-12 | 鞍钢股份有限公司 | High-strength high-strain reinforced V-containing pipeline wide and thick plate and production method thereof |
| CN115572901B (en) * | 2022-09-30 | 2024-01-02 | 鞍钢集团北京研究院有限公司 | 630 MPa-grade high-tempering-stability low-carbon low-alloy steel plate and manufacturing method thereof |
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