CN106244915B - A kind of think gauge X80 pipe fitting steel pipes of excellent in low temperature toughness and preparation method thereof - Google Patents
A kind of think gauge X80 pipe fitting steel pipes of excellent in low temperature toughness and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
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- 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
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
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Abstract
The invention belongs to the technical field of low-alloy high-strength pipe fitting steel pipe manufacture, think gauge X80 pipe fitting steel pipes of a kind of excellent in low temperature toughness and preparation method thereof are specifically related to.The think gauge X80 pipe fitting steel pipes of this kind of excellent in low temperature toughness, chemical composition are as follows according to percentage by weight：C：0.04 0.07%, Si：0.20 0.30%, Mn：1.70 1.90%, P≤0.01%, S≤0.005%, Nb：0.035 0.070%, Mo:0.20 0.25%, Cu:0.10 0.20%, Cr:0.15 0.25%, Ni:0.15 0.30%, Ti：0.03 0.04%, Al：0.01 0.02%, N≤0.005%, 2≤Ti/Al≤3,2≤Al/N≤5, V:0.02‑0.04%；Surplus is Fe and its inevitable impurity.By low-carbon multi microalloy composition design, accurately pipe crimping, welding and Technology for Heating Processing produce the think gauge X80 pipe fitting steel pipes with excellent low temperature toughness performance for comprehensive utilization.
Description
Technical field
The invention belongs to the technical field of low-alloy high-strength pipe fitting steel pipe manufacture, it is excellent to be specifically related to a kind of low-temperature flexibility
Different think gauge X80 pipe fitting steel pipes and preparation method thereof.
Background technology
With going into operation for going into operation successively for petroleum pipeline industry, particularly Sino-Russian eastern line, pipeline need by extremely frigid zones,
A series of severe area of geology such as permafrost, in these area laying pipelines, it is necessary to the low temperature resistant think gauge pipe in part
Part steel pipe.Needed for pipeline partial tube need it is exposed -45 DEG C of temperature at a temperature of, pipe fitting thickness reaches more than 50mm, this kind of
Pipe fitting steel, because alloy content is high, is easily worked hardening in plate rolling tube, on the basis for the intensity for ensureing heat-treated steel pipe
Upper is difficult to take into account low-temperature flexibility again.Therefore, there is an urgent need to the think gauge pipe fitting steel pipe progress to the tenacity excellent under extremely cold environment
Research and production, meet the needs of pipe fitting market.
To meet the requirement of think gauge X80 pipe fitting steel pipe low-temperature flexibility indexs, it is necessary to using its high-performance as target, from composition
It is just careful in detail at the beginning of design, pipe crimping, welding and heat treatment technique to formulate, it can be provided using these technologies and safe and reliable be
The engineer applied of system, Simultaneous Stabilization production and safety.Think gauge X80 pipe fitting steel of the present invention for production high/low temperature tenacity excellent
Many problems of pipe, production practices and technological equipment with reference to scene, are designed, rationally using low-carbon multi microalloy unique component
Control Ti/Al ratios and Al/N ratios, be precisely controlled pipe crimping, welding and heat treatment technique ensures think gauge X80 pipe fitting steel in Re Chu
There is excellent low-temperature flexibility performance after reason, solve that think gauge X80 rank pipe fitting steel roll pipe process windows are narrow, and performance is unstable
The problem of poor toughness after being particularly heat-treated.Realize think gauge X80 pipe fitting steel it is efficient, stably, mass production.To promote
The large-scale industrial production of think gauge pipe fitting steel serves the effect of positive important.
Do not account in the prior art Ti/Al than with Al/N compare pipe fitting steel low-temperature flexibility influence, also not from
System considers composition design, molding technique parameter, prewelding, inside and outside Welding, expanding technology and heat treatment critical process to pipe fitting
The influence of steel low-temperature flexibility, simply it is related to some processes parameter, without the linking and coordination of each technique of overall thinking, it is difficult to
The low-temperature flexibility of stable guarantee pipe fitting steel plate.
The content of the invention
It is an object of the invention to a kind of think gauge X80 pipes of excellent in low temperature toughness are provided for above-mentioned defect
Part steel pipe and preparation method thereof, under the premise of improving produced on-site efficiency and ensureing steel plate steady production, produce with low temperature
The excellent X80 pipe fitting steel pipes of toughness properties.By low-carbon multi microalloy composition design, comprehensive utilization accurately pipe crimping, welding
And Technology for Heating Processing produces the think gauge X80 pipe fitting steel pipes with excellent low temperature toughness performance.
The technical scheme is that：A kind of think gauge X80 pipe fitting steel pipes of excellent in low temperature toughness, chemical composition is according to weight
It is as follows to measure percentage：C：0.04-0.07%, Si：0.20-0.30%, Mn：1.70-1.90%, P≤0.01%, S≤0.005%, Nb：
0.035-0.070%, Mo:0.20-0.25%, Cu:0.10-0.20%, Cr:0.15-0.25%, Ni:0.15-0.30%, Ti：0.03-
0.04%, Al：0.01-0.02%, N≤0.005%, 2≤Ti/Al≤3,2≤Al/N≤5, V:0.02-0.04%, Pcm=C+Si/30
+ (Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.22%,
Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15=0.41%-0.53%；Surplus is for Fe and its inevitably
Impurity.
The think gauge X80 pipe fitting steel pipe preparation methods of the excellent in low temperature toughness, comprise the following steps：（1）Raw steel
Storage and inspection；（2）Steel plate feeding；（3）Steel-plate ultrasound wave inspection；（4）Milling side；（5）Pre-bending；（6）Steel plate forming；（7）Prewelding；
（8）Pre- postwelding inspection, repairing；（9）Interior weldering；（10）1# ultrasonic examinations and visual examination；（11）1#X radiographic inspections and inside weld
Check；（12）Outside weld；（13）Machinery expanding；（14）The water pressure test；（15）Pipe end chamfered edge；（16）2# ultrasonic examinations and outward appearance inspection
Look into；（17）Pipe end magnetic powder inspection；（18）2#X radiographic inspections；（19）Bend shaping；（20）Heat treatment.
The step（4）Milling is 20mm in two side milling of light plate, and steel plate uses JCOE moulding process, first steel plate pressure
Be pressed into " C " shape into " J " shape, then by second half of steel plate, eventually form " O " shape of opening, punching press passage amount to 21 passages or
23 passages, wherein compacting " J " shape passage 4-5 roads, " C " shape passage 13-15 roads, suppress " O " shape passage 3-5 passages, every time pressure
The interval 5-6 seconds carry out lower a time deformation after the completion of system, and reduction in pass is carried out using incremental manner until preferable rate in the wrong, stagnation pressure
Lower amount is 580 ± 3mm.
The step（7）CO2 gas shielded arc weldings are used in prewelding, gas welding wire is diameter 3.2mm CHW-60C welding wires,
Preheated before welding, 15 DEG C -20 DEG C of preheating temperature, gas mixture ratio CO2/ Ar=18%/82%, flow 45-55L/min,
Weld heat input is 6-7KJ/CM, weldering speed 2-3m/min, using DC reverse connection electric current 1050-1250A, voltage 20-26V.
The step（9）First uses DC reverse connection in interior weldering, and the second to four is exchange；First electric current I=
1050-1250A, voltage U=20-26V；Second electric current I=785-920A, voltage U=35-40V；3rd electric current I=685-
820A, voltage U=35-40V；4th electric current I=580~700A, voltage U=35-40V；Distance between weldingwires d=18 ± 2mm, welding speed
Spend V=1.0-1.20m/min, weld heat input 55-70KJ/CM.
The step（12）First uses DC reverse connection in outside weld, and the second to four is exchange；First electric current I=
1050-1250A, voltage U=20-26V；Second electric current I=720-880A, voltage U=35-40V；3rd electric current I=675-
820A, voltage U=35-40V；4th electric current I=630~750A, voltage U=35-40V；Distance between weldingwires d=18 ± 2mm, welding speed
Spend V=1.00-1.20m/min.
The step（13）Machinery expanding rate is 0.50-0.55% in machinery expanding.
The step（20）Integral quenching+low-temperature insulation+tempering heat treatment process, hardening heat 880 are used in heat treatment
DEG C -930 DEG C, Quenching Soaking Time is according to 3.0min/mm, and hardening media is mass fraction 15%NaCl salt solution, low-temperature insulation temperature
Spend for 150-180 DEG C, thermal insulation medium is silicone oil, soaking time 20-30min, 650 ± 50 DEG C of temperature, and tempering time is
4.2min/mm, room temperature is cooled to the furnace after tempering.
Beneficial effects of the present invention are：The think gauge X80 pipe fittings steel pipe of excellent in low temperature toughness of the present invention its into setting up separately
The effect of each element is as follows in meter：
C：Carbon is to improve the main and most cheap element of intensity, and with the increase of carbon content, the intensity of steel increases, but
The welding performance of steel plate and plasticity and toughness are deteriorated simultaneously, therefore the present invention selects low-carbon composition design so that steel plate has good
Plasticity and toughness and excellent welding performance.
Mn：Manganese is the effective element for improving intensity and toughness, and it is weak carbide formation element, its effect in smelting
Be deoxidation and eliminate the influence of sulphur, can also reduce austenite transformation temperature, fining ferrite grains, to improve armor plate strength and
Toughness is beneficial.Simultaneously can also solution strengthening ferrite and increase steel quenching degree.It has to bainite transformation under the conditions of low-carbon
Significant facilitation.But during Mn too high levels, then hardening of steel and ductility degenerates.Mn because of its positive effect, cost it is cheap
Turn into one of main addition element in quality plate production.
Si：Silicon plays a part of deoxidier, while has solution strengthening effect, can also greatly delay the shape of carbide
Into lagging growing up for cementite, add stabilization of austenite.But Si contents are high, easily there is field trash in steel grade, and steel are easily raw
Rust, iron rust is easily rolled into steel plate top layer, galvanizing poor performance, while Si and all shown when being welded to multithreading in hot rolling production
Local brittle zones have harmfulness.
Cu：The precipitation strength of copper is the important means for the intensity for improving steel, in addition, Cu to the corrosion resistance of steel, improve
Weldability, low-temperature flexibility, mouldability and machinability etc. are all highly profitable.But on the other hand, continuous casting steel when Cu contents are high
Crackle is also easy to produce when base heating or hot rolling, deteriorates surface of steel plate performance, it is necessary to add according to the difference of intensity rank and steel plate thickness
Add appropriate Ni to prevent the generation of this crackle.
Ni：Nickel does not have harmful effect to welding heat affected zone hardening and toughness, the intensity of mother metal can again improved, and make
Low-temperature flexibility greatly improves.But it is that the cost for causing steel compared with noble element significantly rises, less economical.Added in steel
The purpose of Ni elements is mainly the tendency that the steel billet for preventing amount containing Cu high cracks in heating or hot rolling.According to containing for Cu
Amount, by the control of Ni contents at 0.7-1 times of Cu contents.
Ti：Micro titanium is added, is to fix the nitrogen in steel.Other Ti has strong precipitation strength effect, can
To improve the intensity of steel, the influence also having had to the hardness at welding heat affected zone in the best condition, Ti nitride
The presence of particle can suppress the length of grain coarsening prevention steel billet crystal grain in heating, rolling, welding process of welding heat affected zone
Greatly, the toughness of mother metal and welding heat affected zone is improved.When Ti is less than 0.005%, Gu N effects are poor, during more than 0.03%, Gu N effects
Reach saturation, superfluous Ti can form carbonitride individually or together with Nb, strengthen steel, but form the analysis of bulk sometimes
Go out phase, it will deteriorate the toughness of steel.When the ratio between Ti, N atom in steel is 1：When 1, TiN particles are the most tiny and are distributed more
Dissipate, it is most strong to the refining effect of high temperature austenite crystal grain, can not only obtain excellent toughness, and can realize 30KJ/cm with
On Large Heat Input Welding.It is unfavorable to low-temperature flexibility but excessive Ti contents can cause the roughening of the nitride of titanium.Therefore,
Typically by Ti Composition Controls 0.02% or so.
Cr：The addition of chromium can reduce the transformation temperature of steel grade, thinning microstructure, effectively improve intensity, can also improve steel
Kind of inoxidizability and high temperature corrosion-resisting performance etc., but Cr is crossed and is at most separated out thick, causes the embrittlement of steel, to welding performance not
It is good, therefore Cr contents are designed as≤0.30%.
Ti/Al ratios：The TI systems oxidation that Ti mainly forms small and dispersed distribution using molten steel in process of setting is added in steel
Thing, these oxides can induce the formation of acicular ferrite inside austenite crystal（Intragranular Acicular Ferrite）, so as to play refinement
The effect of crystal grain, the appropriate Ti contents reduction Al content that increases can avoid the formation of Al2O3Promotion forms tiny Ti2O3, but it is too low
Ti/Al ratios be not enough to be formed the Ti of enough small and disperseds2O3, to form a thick field trash anti-than easy by too high Ti/Al
And it is unfavorable to the performance of steel, therefore, the present invention will be designed as 2≤Ti/Al≤3.
Al/N ratios：The performance that Al/N compares pipe fitting steel has a major impact, and suitable Al/N ratios can be with crystal grain thinning and improvement
The toughness of steel, reduce the ductile-brittle transition temperature of steel, it is necessary to control Al/N ratios and its content, the present invention is by Al/N than control 2
Between≤Al/N≤5.
- 45 DEG C of mother metal impact >=350J of pipeline steel tube that the present invention is produced, the section of shear is 100%, and weld impingement >=
250J, the section of shear are 100%；Heat affected area impact is >=290J, and the section of shear is >=85%.Think gauge X80 pipe fitting steel is low
Warm toughness properties are excellent.
Manufacture method of the present invention is the rationally control on the basis of above-mentioned low-carbon combined microalloying composition design
Ti/Al ratios and Al/N ratios, it is precisely controlled pipe crimping, welding and heat treatment technique ensures think gauge X80 pipe fittings steel after heat treatment
With excellent low-temperature flexibility performance, solution think gauge X80 rank pipe fitting steel roll pipe process windows are narrow, and performance is unstable particularly
The problem of poor toughness after heat treatment.Realize think gauge X80 pipe fitting steel it is efficient, stably, mass production.
Designed using low-carbon multi microalloy unique component, rationally control Ti/Al ratios and Al/N ratios, be precisely controlled pipe crimping,
Welding and heat treatment technique ensures that think gauge X80 pipe fittings steel has excellent low-temperature flexibility performance after heat treatment, solves
Think gauge X80 rank pipe fitting steel roll pipe process windows are narrow, the problem of poor toughness after the unstable particularly heat treatment of performance.Realize
Think gauge X80 pipe fitting steel it is efficient, stably, mass production.To promote the large-scale industrial production of think gauge pipe fitting steel to rise
The effect of positive important is arrived.The think gauge X80 pipe fittings steel pipe and manufacture method of the excellent in low temperature toughness, comprising with above-mentioned chemistry
Composition pure steel smelting, incrementally JCOE moulding process accordingly, CO2 gas shield tack welding process, interior outside weld and expanding system
Control technology, and the technique such as " quenching+low-temperature insulation+tempering heat treatment process " overall with steel pipe.
The original thickness of strand of the present invention is 250mm.
In summary, the present invention is designed using low-carbon multi microalloy unique component, strict to control Ti/Al ratios and Al/N ratios
Within the specific limits, in particular with Ti and Al deoxidations and crystal grain refinement, play each element characteristic and mutual collaboration is made
With, it is ingenious using incrementally JCOE moulding process, by CO2 gas shield preweldings, it is precisely controlled interior outside weld and reaming key work
Skill parameter, originality invention steel pipe is overall " quenching+low-temperature insulation+tempering heat treatment process ", realizes the low of think gauge pipe fitting steel
Warm toughness properties, take into account the feasibility and security of pipe rolling technique, large-scale industrial production preferably.
Brief description of the drawings
Fig. 1 is the metallograph of mother metal tissue in the present invention.
Fig. 2 is the metallograph of seam organization in the present invention.
Fig. 3 is the metallograph that heat affected area is organized in the present invention.
Embodiment
Below by embodiment, the present invention will be described in detail.
Embodiment 1
The think gauge X80 pipe fitting steel pipes of the excellent in low temperature toughness are prepared by the component of following mass percent：
C：0.04%, Si：0.20%, Mn：1.70%, P=0.005%, S=0.001%, Nb：0.035%, Mo:0.20%, Cu:0.10%, Cr:
0.15%, Ni:0.15%, Ti：0.03%, Al：0.01%, N=0.002%, Ti/Al=3, Al/N=5, V:0.02%,Pcm=0.16%,
Ceq =0.41%。
Surplus is Fe and inevitable impurity.
The preparation method is as follows：
1）Steel plate milling side, molding procedure：The side milling side of steel plate two is 20mm, and steel plate uses JCOE moulding process, first steel
Plate is pressed into " J " shape, then second half of steel plate is pressed into " C " shape, eventually forms " O " shape of opening, and punching press passage amounts to 21 passages,
Wherein suppress " J " shape passage 4, " C " shape passage 13, the passage of compacting " O " shape passage 4, interval 5 seconds after the completion of every time compacting
Lower a time deformation is carried out, reduction in pass is carried out using incremental manner until preferable rate in the wrong, overall reduction 577mm.
2）Steel pipe prewelding process：Using CO2 gas shielded arc weldings, gas welding wire is diameter 3.2mm CHW-60C welding wires, is welded
Preheated before connecing, 15 DEG C of preheating temperature, gas mixture ratio is CO2/Ar=18%/82%, flow 45L/min, weld heat input
For 6KJ/CM, weldering speed 2m/min, using DC reverse connection electric current 1050A, voltage 20V.
3）Welder's sequence in steel pipe：First uses DC reverse connection, and the second to four is exchange；First electric current I=1050A,
Voltage U=2V；Second electric current I=785A, voltage U=35V；3rd electric current I=685A, voltage U=35V；4th electric current I=
580A, voltage U=35V；Distance between weldingwires d=16mm, welding speed V=1.0m/min, weld heat input 55KJ/CM.
4）Steel pipe outside weld process：First uses DC reverse connection, and the second to four is exchange；First electric current I=1050A,
Voltage U=20V；Second electric current I=720A, voltage U=35V；3rd electric current I=675A, voltage U=35V；4th electric current I=
630A, voltage U=35V；Distance between weldingwires d=16mm, welding speed V=1.0m/min.
5）Machinery expanding process：Steel pipe total length machinery expanding rate is 0.50%.
6）Heat treatment step：Steel pipe uses integral quenching+low-temperature insulation+tempering heat treatment process, 880 DEG C of hardening heat,
For Quenching Soaking Time according to 3.0min/mm, hardening media is the salt solution that concentration is 15%NaCl, and low-temperature insulation temperature is 150 DEG C,
Thermal insulation medium is silicone oil, soaking time 20min, 600 DEG C of temperature, tempering time 4.2min/mm, cold with stove after tempering
But to room temperature.
7）After testing, the main performance of this example is as follows：It is characterized in that：The impact of -45 DEG C of mother metals is 380J, 400J,
392J, the section of shear 100%, 100%, 100%；Weld impingement is 280J., 286J, 290J, the section of shear 100%, 100%,
100%；Heat affected area impact is 310J, 321J, 318J, the section of shear 95%, 92%, 95%.
Embodiment 2
The think gauge X80 pipe fitting steel pipes of the excellent in low temperature toughness are prepared by the component of following mass percent：
C：0.07%, Si：0.30%, Mn：1.90%, P=0.010%, S=0.005%, Nb：0.070%, Mo:0.25%, Cu:20%, Cr:
0.25%, Ni:0.30%, Ti：0.04%, Al：0.02%, N=0.005%, Ti/Al=3, Al/N=2, V:0.04%,Pcm=0.22%,
Ceq =0.53%。
The preparation method is as follows：
1）Steel plate milling side, molding procedure：The side milling side of steel plate two is 20mm, and steel plate uses JCOE moulding process, first steel
Plate is pressed into " J " shape, then second half of steel plate is pressed into " C " shape, eventually forms " O " shape of opening, and punching press passage amounts to 23 passages,
Wherein suppress " J " shape passage 5, " C " shape passage 15, the passage of compacting " O " shape passage 3, interval 6 seconds after the completion of every time compacting
Lower a time deformation is carried out, reduction in pass is carried out using incremental manner until preferable rate in the wrong, overall reduction 583mm.
2）Steel pipe prewelding process：Using CO2 gas shielded arc weldings, gas welding wire is diameter 3.2mm CHW-60C welding wires, is welded
Preheated before connecing, 20 DEG C of preheating temperature, gas mixture ratio is CO2/Ar=18%/82%, flow 55L/min, weld heat input
For 7KJ/CM, weldering speed 3m/min, using DC reverse connection electric current 1250A, voltage 26V.
3）In steel pipe in welder's sequence：First uses DC reverse connection, and the second to four is exchange；First electric current I=
1250A, voltage U=26V；Second electric current I=920A, voltage U=40V；3rd electric current I=820A, voltage U=40V；4th
Electric current I=700A, voltage U=40V；Distance between weldingwires d=20mm, welding speed V=1.20m/min, weld heat input 70KJ/CM.
4）Steel pipe outside weld process：First uses DC reverse connection, and the second to four is exchange；First electric current I=1250A,
Voltage U=26V；Second electric current I=880A, voltage U=40V；3rd electric current I=820A, voltage U=40V；4th electric current I=
750A, voltage U=40V；Distance between weldingwires d=20mm, welding speed V=1.20m/min.
5）Machinery expanding process：Steel pipe total length machinery expanding rate is 0.55%.
6）Heat treatment step：Steel pipe uses integral quenching+low-temperature insulation+tempering heat treatment process, 930 DEG C of hardening heat,
For Quenching Soaking Time according to 3.0min/mm, hardening media is the salt solution that concentration is 15%NaCl, and low-temperature insulation temperature is 180 DEG C,
Thermal insulation medium is silicone oil, soaking time 30min, 700 DEG C of temperature, tempering time 4.2min/mm, cold with stove after tempering
But to room temperature.
7）After testing, the main performance of this example is as follows：It is characterized in that：The impact of -45 DEG C of mother metals is 360J, 365J,
372J, the section of shear 100%, 100%, 100%；Weld impingement is 270J., 277J, 272J, the section of shear 100%, 100%,
100%；Heat affected area impact is 300J, 295J, 298J, the section of shear 93%, 90%, 95%.
Embodiment 3
The think gauge X80 pipe fitting steel pipes of the excellent in low temperature toughness are prepared by the component of following mass percent：
C：0.05%, Si：0.25%, Mn：1.80%, P=0.008%, S=0.002%, Nb：0.050%, Mo:0.20%, Cu:0.15%, Cr:
0.20%, Ni:0.20%, Ti：0.031%, Al：0.015%, N=0.004%, Ti/Al=2, Al/N=3.75, V:0.03%,Pcm=
0.19%,Ceq =0.46%。
The preparation method is as follows：
1）Steel plate milling side, molding procedure：The side milling side of steel plate two is 20mm, and steel plate uses JCOE moulding process, first steel
Plate is pressed into " J " shape, then second half of steel plate is pressed into " C " shape, eventually forms " O " shape of opening, and punching press passage amounts to 23 passages,
Wherein suppress " J " shape passage 4, " C " shape passage 14, the passage of compacting " O " shape passage 5, interval 5.5 after the completion of every time compacting
Second carries out lower a time deformation, and reduction in pass is carried out using incremental manner until preferable rate in the wrong, overall reduction 580mm.
2）Steel pipe prewelding process：Using CO2Gas shielded arc welding, gas welding wire are diameter 3.2mm CHW-60C welding wires, are welded
Preheated before connecing, 18 DEG C of preheating temperature, gas mixture ratio is CO2/Ar=18%/82%, flow 50L/min, weld heat input
For 6.5KJ/CM, weldering speed 2.5m/min, using DC reverse connection electric current 1150A, voltage 25V.
3）In steel pipe in welder's sequence：First uses DC reverse connection, and the second to four is exchange；First electric current I=
1150A, voltage U=25V；Second electric current I=800A, voltage U=38V；3rd electric current I=700A, voltage U=38V；4th
Electric current I=600A, voltage U=38V；Distance between weldingwires d=18mm, welding speed V=1.10m/min, weld heat input 60KJ/CM.
4）Steel pipe outside weld process：First uses DC reverse connection, and the second to four is exchange；First electric current I=1150A,
Voltage U=25V；Second electric current I=800A, voltage U=38V；3rd electric current I=720A, voltage U=38V；4th electric current I=
700A, voltage U=38V；Distance between weldingwires d=18mm, welding speed V=1.10m/min.
5）Machinery expanding process：Steel pipe total length machinery expanding rate is 0.53%.
6）Heat treatment step：Steel pipe uses integral quenching+low-temperature insulation+tempering heat treatment process, 900 DEG C of hardening heat,
For Quenching Soaking Time according to 3.0min/mm, hardening media is the salt solution that concentration is 15%NaCl, and low-temperature insulation temperature is 160 DEG C,
Thermal insulation medium is silicone oil, soaking time 25min, 650 DEG C of temperature, tempering time 4.2min/mm, cold with stove after tempering
But to room temperature.
7）After testing, the main performance of this example is as follows：It is characterized in that：The impact of -45 DEG C of mother metals is 370J, 365J,
372J, the section of shear 100%, 100%, 100%；Weld impingement is 275., 280J, 268J, the section of shear 100%, 100%,
100%；Heat affected area impact is 295J, 298J, 300J, the section of shear 90%, 92%, 93%.
Claims (8)
- A kind of 1. think gauge X80 pipe fitting steel pipes of excellent in low temperature toughness, it is characterised in that chemical composition according to weight percent such as Under：C：0.04-0.07%, Si：0.20-0.30%, Mn：1.70-1.90%, P≤0.01%, S≤0.005%, Nb：0.035- 0.070%, Mo:0.20-0.25%, Cu:0.10-0.20%, Cr:0.15-0.25%, Ni:0.15-0.30%, Ti：0.03-0.04%, Al：0.01-0.02%, N≤0.005%, 2≤Ti/Al≤3,2≤Al/N≤5, V:0.02-0.04%, Pcm=C+Si/30+ (Mn+ Cu+Cr)/20+Ni/60+Mo/15+V/10+5B≤0.22%,Ceq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15=0.41%-0.53%；Surplus is Fe and its inevitable impurity； Described -45 DEG C of mother metal impact >=350J of pipe fitting steel pipe, the section of shear is 100%, weld impingement >=250J, and the section of shear is 100%；Heat affected area impact is >=290J, and the section of shear is >=85%.
- 2. a kind of think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness described in claim 1, comprise the following steps： （1）Raw steel is put in storage and examined；（2）Steel plate feeding；（3）Steel-plate ultrasound wave inspection；（4）Milling side；（5）Pre-bending；（6）Steel plate into Type；（7）Prewelding；（8）Pre- postwelding inspection, repairing；（9）Interior weldering；（10）1# ultrasonic examinations and visual examination；（11）1#X rays Flaw detection and inside weld inspection；（12）Outside weld；（13）Machinery expanding；（14）The water pressure test；（15）Pipe end chamfered edge；（16）2# ultrasonic waves Flaw detection and visual examination；（17）Pipe end magnetic powder inspection；（18）2#X radiographic inspections；（19）Bend shaping；（20）Heat treatment.
- 3. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（4）Milling is 20mm in two side milling of light plate, and steel plate uses JCOE moulding process, steel plate is first pressed into " J " shape, then Second half by steel plate is pressed into " C " shape, eventually forms " O " shape of opening, and punching press passage amounts to 21 passages or 23 passages, wherein " J " shape passage 4-5 roads are suppressed, " C " shape passage 13-15 roads, suppress " O " shape passage 3-5 passages, interval after the completion of every time compacting The 5-6 seconds carry out lower a time deformation, and reduction in pass is carried out using incremental manner, and overall reduction is 580 ± 3mm.
- 4. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（7）CO is used in prewelding2Gas shielded arc welding, gas welding wire are diameter 3.2mm CHW-60C welding wires, are carried out before welding Preheating, 15 DEG C -20 DEG C of preheating temperature, gas mixture ratio CO2/ Ar=18%/82%, flow 45-55L/min, weld heat input For 6-7k J/ ㎝, weldering speed 2-3m/min, using DC reverse connection electric current 1050-1250A, voltage 20-26V.
- 5. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（9）First uses DC reverse connection in interior weldering, and the second to four is exchange；First electric current I=1050-1250A, electricity Press U=20-26V；Second electric current I=785-920A, voltage U=35-40V；3rd electric current I=685-820A, voltage U=35- 40V；4th electric current I=580~700A, voltage U=35-40V；Distance between weldingwires d=18 ± 2mm, welding speed V=1.0-1.20m/ Min, weld heat input are 55-70 k J/ ㎝.
- 6. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（12）First uses DC reverse connection in outside weld, and the second to four is exchange；First electric current I=1050-1250A, electricity Press U=20-26V；Second electric current I=720-880A, voltage U=35-40V；3rd electric current I=675-820A, voltage U=35- 40V；4th electric current I=630~750A, voltage U=35-40V；Distance between weldingwires d=18 ± 2mm, welding speed V=1.00- 1.20m/min。
- 7. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（13）Machinery expanding rate is 0.50-0.55% in machinery expanding.
- 8. the think gauge X80 pipe fitting steel pipe preparation methods of excellent in low temperature toughness according to claim 2, it is characterised in that institute State step（20）Integral quenching+low-temperature insulation+tempering heat treatment process is used in heat treatment, 880 DEG C -930 DEG C of hardening heat, is quenched Fiery soaking time is mass fraction 15%NaCl salt solution according to 3.0min/mm, hardening media, and low-temperature insulation temperature is 150-180 DEG C, thermal insulation medium is silicone oil, soaking time 20-30min, 650 ± 50 DEG C, tempering time 4.2min/mm of temperature, is returned Cool to room temperature after fire with the furnace.
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| CN103556079A (en) * | 2013-10-14 | 2014-02-05 | 宝鸡石油钢管有限责任公司 | High-strength water riser main-pipe with excellent anti-fatigue performance and manufacturing method thereof |
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