CN105154779B - A kind of seamless steel tube for nuclear power and preparation method thereof - Google Patents
A kind of seamless steel tube for nuclear power and preparation method thereof Download PDFInfo
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- CN105154779B CN105154779B CN201510516129.2A CN201510516129A CN105154779B CN 105154779 B CN105154779 B CN 105154779B CN 201510516129 A CN201510516129 A CN 201510516129A CN 105154779 B CN105154779 B CN 105154779B
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Abstract
The present invention relates to a kind of seamless steel pipe and preparation method thereof, and in particular to a kind of nuclear power thick-walled seamless steel pipes and preparation method thereof.Seamless steel pipe of the present invention, its steel billet is made up of following weight percent composition：C 0.13~0.15%, Si 0.15~0.38%, Mn 0.80~1.20%, P≤0.015%, S≤0.001%, Cr≤0.25%, Ni≤0.50%, Mo≤0.10%, Cu≤0.18%, Al 0.020~0.050%, Sn≤0.03%, surplus is Fe.The component segregation and banded structure of P280GH thick walled steel tubes prepared by the present invention substantially mitigate, original austenite grain and ferrite crystal grain are refined, so as to significantly improve its transverse impact toughness and other mechanical properties, its metallographic structure also disclosure satisfy that the requirement of RCC M standards.
Description
Technical field
The present invention relates to a kind of seamless steel pipe and preparation method thereof, and in particular to a kind of nuclear power thick-walled seamless steel pipes and its
Preparation method.
Background technology
P280GH is French specification RCC-M《Presurized water reactor nuclear islands equipment designs and built specification》In to define high temperature special
Property carbon steel seamless steel tube kind, be widely used in pressurized-water reactor nuclear power plant main steam system, steam generator feedwater flow control, auxiliary
Help water supply system and turbine bypass system etc..
Because its use condition is special, safe class is high, so the requirement to steel pipe tissue and toughness is used far above thermoelectricity
Pipe, such as：Metallographic structure should be ferrite+pearlite, and -20 DEG C of low-temperature impact work will reach 60J, diameter of steel tube and wall thickness foot
Side knock experiment should be done with process lateral impact sample.At present, the underproof item of P280GH mechanical properties of pipe is caused
Mesh is mainly impact property, particularly wall thickness can not often meet RCC-M in the side knock performance of 20~50mm thick-walled pipe
The requirement of specification.
P280GH steel carbon manganese component segregation is serious, causes the banded structure rank of its fished pipe higher, is generally more than
2.5 level.Because banded structure causes the anisotropy of steel, bring very big to impact property, particularly side knock performance
Negative effect.
Further, since RCC-M specifications are delivered goods to P280GH steel pipes, the metallographic structure of state is limited, it is desirable to its metallographic group
Ferrite+pearlite is woven to, so the final heat treatment of P280GH steel pipes typically can only be using normalizing heat treatment, and can not be to carry
The method of its high impact property and use Tempering and Quenching.
The content of the invention
First technical problem to be solved by this invention, which is to provide one kind, can not only significantly improve P280GH heavy wall steel
The low temperature impact properties of pipe, and meet RCC-M specifications steel pipe is delivered goods state metallographic structure requirement heavy wall nuclear power with seamless
Steel pipe.
A kind of seamless steel tube for nuclear power of the present invention, its steel billet is made up of following weight percent composition：C 0.13~
0.15%th, Si0.15~0.38%, Mn 0.80~1.20%, P≤0.015%, S≤0.001%, Cr≤0.25%, Ni≤
0.50%th, Mo≤0.10%, Cu≤0.18%, Al 0.020~0.050%, Sn≤0.03%, surplus is Fe.
Further, as preferred technical scheme, a kind of seamless steel tube for nuclear power of the present invention, its steel billet is by following
Weight percent composition is constituted：C 0.128~0.136%, Si 0.28~0.32%, Mn 0.98~1.05%, P≤
0.012%th, S≤0.0008%, Cr≤0.15%, Ni≤0.09%, Mo≤0.04%, Cu≤0.08%, Al 0.032~
0.035%th, Sn≤0.008%, surplus is Fe.
Further, as preferred technical scheme, a kind of seamless steel tube for nuclear power of the present invention, its steel billet is by following
Weight percent composition is constituted：C 0.136%, Si 0.28%, Mn 1.05%, P 0.012%, S 0.0008%, Cr
0.12%th, Ni 0.08%, Mo 0.04%, Cu 0.08%, Al 0.032%, Sn 0.008%, surplus is Fe.
Or as preferred technical scheme, its steel billet is made up of following weight percent composition：C 0.128%, Si
0.32%th, Mn 0.98%, P 0.011%, S 0.0006%, Cr 0.15%, Ni 0.09%, Mo 0.04%, Cu
0.08%th, Al 0.035%, Sn 0.007%, surplus is Fe.
A kind of seamless steel tube for nuclear power described above, yield strength >=298MPa of steel pipe, tensile strength >=520MPa ,-
20 DEG C of ballistic work >=80J, metallographic structure be ferrite+pearlite, ferrite grain size≤8.0 grade, banded structure≤2.0 grade,
Lengthening coefficient >=5.5.
Due to molten steel in ingot casting crystallization process selective crystallization and formed chemical composition be in uneven distribution dendrite group
Knit, the large dendritic crystal in ingot casting is elongated in rolling along deformation direction, and gradually consistent with deformation direction, thus formed carbon and
The dilution band and enrichment band of alloying element are alternating with each other to be stacked, under the conditions of slow cooling, is first separated out in carbon and alloying element dilution band
Eutectoid ferrite, and unnecessary carbon is discharged into the enrichment band of both sides, ultimately form the band based on ferrite；And carbon and alloy member
Plain enrichment band forms the band based on pearlite behind, thus form the band based on ferrite with based on pearlite
With banded structure alternating with each other.Component segregation is more serious, and the banded structure of formation is also more serious.Due to banded structure adjacent belts
Microscopic structure it is different, their performance is also differed, with obvious anisotropy.When carrying out side knock experiment, by force
Stress concentration can be produced between weak band, causes side knock performance substantially relatively low.
P280GH steel is the higher carbon steel of manganese content, and ingot casting arborescent structure segregation is more serious, causes its fished pipe
Banded structure rank is high, the side knock performance of steel pipe is remarkably decreased.Therefore, the transverse direction of P280GH thick-walled seamless steel pipes is improved
Impact property, should improve the carbon manganese component segregation of P280GH steel first.
Therefore, second technical problem to be solved by this invention, which is to provide one kind, can be obviously improved steel pipe component segregation
Seamless steel tube for nuclear power preparation method.
A kind of preparation method of seamless steel tube for nuclear power of the present invention, comprises the following steps：
A, smelting casting：Using steel scrap and sponge iron as raw material, melting, tapping, continuous casting obtains continuous casting billet；
The present invention uses high-quality steel scrap and sponge iron for raw material, ultra high electric arc furnace melting can be used, by eccentric stove
Tap at bottom, it is ensured that stay steel to stay slag, slag free tapping；
B, hot rolling tube rolling：The continuous casting billet that a steps are obtained is heated to 1260~1280 DEG C, is incubated 6~7h；Come out of the stove, treat temperature
When degree drops to 1210~1230 DEG C, eleven punch 11 is entered to pipe；Tube rolling is carried out after perforation, finishing temperature is 860~900 DEG C；
According to the specification of fished pipe using the pipe of dimension, it is ensured that lengthening coefficient >=5.5 of steel pipe；To pipe
The implementation on conic perforator can be used by entering eleven punch 11；
C, heat treatment：It is divided into the pre-heat treatment and is heat-treated eventually；
Wherein, the pre-heat treatment is that the steel pipe that is rolled into b step is air-cooled to 300~400 DEG C and enters stove, is heated to 630~650
After DEG C, according to thickness of steel pipe meter, 1.5~2min/mm is incubated；Continue to be heated to 960~980 DEG C, be incubated 6~8h；It is cold with stove again
To 555~565 DEG C, 5~6h is incubated；Finally with being furnace-cooled to after 500 DEG C, come out of the stove and be air-cooled to room temperature；
It is that the good steel pipe of the pre-heat treatment is carried out into normalizing heat treatment to be heat-treated eventually, using pressure cooling side after normalizing heat treatment
Formula；
Wherein, the normalizing temperature of normalizing heat treatment is 890~910 DEG C, according to thickness of steel pipe meter, is incubated 2.5~3min/
mm；
Force cooling to use temperature for 10~50 DEG C of cooling medium, again take out steel pipe after cooling down the of short duration time, in sky
Room temperature is cooled in gas, is produced.
Ladle furnace is whole when melting is refined in a kind of preparation method of seamless steel tube for nuclear power described above, wherein a steps
Argon is stirred, and molten steel is through vacuum outgas and feeds the processing of silicon-aluminium wire, it is ensured that the stabilization of molten steel composition and pure；Using electricity during continuous casting
Magnetic is stirred and soft pressure measure, and control molten steel is poured into a mould under low overheat, to mitigate the component segregation of pipe.
A kind of preparation method of seamless steel tube for nuclear power described above, the cooling medium of the pressure cooling wherein in step c
For 32# machine oil, and as thickness of steel pipe 20mm ＜ D≤30mm, 45~65s is cooled down；During 30mm ＜ D≤40mm, cooling 66~
95s；During 40mm ＜ D≤50mm, 96~126s is cooled down；So, the normalizing cooling rate of P280GH steel pipes can be improved, iron can be obtained again
The metallographic structure of ferritic+pearlite.
The present invention is smelting casting process, is existed when employing continuous casting using electromagnetic agitation and soft pressure measure and control molten steel
The method poured into a mould under low overheat mitigates the component segregation of pipe.
Present inventor has further discovered that, when pipe heating-up temperature be 1300 DEG C, soaking time be 16~18h when, steel
In carbon manganese component segregation will thoroughly be improved, but at the same time can bring that the oxidation and decarbonization and scaling loss of pipe be serious, crystal grain
The problem of abnormal thick, energy resource consumption is big, production cost is high, therefore, in annular furnace heating process, the present invention manages P280GH
The heating-up temperature of base brings up to 1260~1280 DEG C from usually used 1210~1230 DEG C, and soaking time extends to 6 from 3~5h
~7h, by accelerating carbon, the diffusion velocity of manganese and other alloying elements and the method for extending diffusion time so that in P280GH steel
Carbon manganese component segregation obtain a certain degree of improvement, while the oxidation and decarbonization and scaling loss lesser extent of pipe, crystal grain also will not
Abnormal growth.
, must be to pipe to refine the grain size of fished pipe because the heating-up temperature of above-mentioned pipe is higher, soaking time is longer
Base is fully deformed.The present invention employs the pipe of dimension according to the specification of fished pipe, to ensure prolonging for steel pipe
Stretch coefficient >=5.5 so that the deflection of steel pipe disclosure satisfy that the requirement of crystal grain thinning.
The present invention controls the piercing temperature of pipe at 1210~1230 DEG C, becomes by using under relatively low piercing temperature
Shape and finishing temperature control is refined into the crystal grain of fished pipe in 860~900 DEG C of method.
Although this invention takes the measure for the lengthening coefficient, piercing temperature, finishing temperature for controlling steel pipe, due to pipe
Heating-up temperature is higher, soaking time is longer, fished pipe there will still likely be the phenomenon of coarse grains, mixed crystal, therefore, this hair
It is bright that the pre-heat treatment has been carried out before steel pipe final heat treatment.
In the pre-heat treatment, preheated after the P280GH steel pipes for rolling completion are heated into 630~650 DEG C first, with
Reduce the thermal stress in heating process, it is to avoid steel pipe ftractures；Fully it is incubated after being heated to 960~980 DEG C again afterwards, utilizes carbon atom
The principle that diffusion velocity is dramatically speeded up more than 950 DEG C reduces the carbon segregation in steel, while mitigating the manganese segregation in steel；Insulation
Afterwards, 555~565 DEG C of fully insulations are furnace-cooled to, the statenchyma of ferrite+carbide are obtained, so as to cut off original thick crystalline substance
The Structure Inheritance of grain and mixed crystal, has obtained the austenite crystal of fine uniform, meanwhile, the carbon manganese component segregation in steel is also obtained
A certain degree of improvement.
In final normalized treatment, to improve banded structure, the present invention is first by the normalizing soaking time generally used
2.5~3min/mm is brought up to from 1.5~2min/mm, to improve the uniform of alloying elements distribution in normalizing austenitization
Property, by taking the method for mitigation component segregation to improve the banded structure of fished pipe..
Secondly, employ and carry out the method for air cooling after short stay to accelerate normalizing cooling rate in 32# machine oil by steel pipe, make
Overcooling austenite changes at a lower temperature, and carbon can not fully be diffused into carbide former enrichment area, so, not only may be used
To significantly improve its banded structure, but also can be with the size of fining ferrite grains and pearlite colony.
The present invention is from cooling medium of the 32# machine oil as normalized treatment, using the cooling capacity of 32# machine oil substantially compared with water
It is cold poor and be slightly faster than the characteristics of mist is cold.Because P280GH steel is low carbon manganese steel, carbon and alloying element content are low, and quenching degree is poor；
And the size of P280GH thick walled steel tubes is between 20~50mm, thermal capacity is larger.Therefore, when P280GH thick walled steel tube austenites
Can not occur bainite or martensitic traoformation after short stay in immersion 32# machine oil after change, while can realize that quickening normalizing is cold
Speed and the purpose for improving cooling uniformity.In addition, in normalizing procedure, the liquid temperature of 32# machine oil should be controlled at 10~50 DEG C, it is to avoid
Answer high oil temperature and influence the service life of machine oil.
The component segregation and banded structure of P280GH thick walled steel tubes prepared by the present invention substantially mitigate, original austenite grain and
Ferrite crystal grain is refined, so as to significantly improve its transverse impact toughness and other mechanical properties, its metallographic structure also can
Enough meet RCC-M《Presurized water reactor nuclear islands equipment designs and built specification》Requirement.
Brief description of the drawings
The metallographic structure (100 ×) for the P280GH steel pipes that Fig. 1 is Ф 168.3 × 22 in embodiment 1；
The metallographic structure (100 ×) for the P280GH steel pipes that Fig. 2 is Ф 457 × 37 in embodiment 2.
Embodiment
A kind of seamless steel tube for nuclear power of the present invention, its steel billet is made up of following weight percent composition：C 0.13~
0.15%th, Si0.15~0.38%, Mn 0.80~1.20%, P≤0.015%, S≤0.001%, Cr≤0.25%, Ni≤
0.50%th, Mo≤0.10%, Cu≤0.18%, Al 0.020~0.050%, Sn≤0.03%, surplus is Fe.
Further, as preferred technical scheme, a kind of seamless steel tube for nuclear power of the present invention, its steel billet is by following
Weight percent composition is constituted：C 0.128~0.136%, Si 0.28~0.32%, Mn 0.98~1.05%, P≤
0.012%th, S≤0.0008%, Cr≤0.15%, Ni≤0.09%, Mo≤0.04%, Cu≤0.08%, Al 0.032~
0.035%th, Sn≤0.008%, surplus is Fe.
Further, as preferred technical scheme, a kind of seamless steel tube for nuclear power of the present invention, its steel billet is by following
Weight percent composition is constituted：C 0.136%, Si 0.28%, Mn 1.05%, P 0.012%, S 0.0008%, Cr
0.12%th, Ni 0.08%, Mo 0.04%, Cu 0.08%, Al 0.032%, Sn 0.008%, surplus is Fe.
Or as preferred technical scheme, its steel billet is made up of following weight percent composition：C 0.128%, Si
0.32%th, Mn 0.98%, P 0.011%, S 0.0006%, Cr 0.15%, Ni 0.09%, Mo 0.04%, Cu
0.08%th, Al 0.035%, Sn 0.007%, surplus is Fe.
A kind of seamless steel tube for nuclear power described above, yield strength >=298MPa of steel pipe, tensile strength >=520MPa ,-
20 DEG C of ballistic work >=80J, metallographic structure be ferrite+pearlite, ferrite grain size≤8.0 grade, banded structure≤2.0 grade,
Lengthening coefficient >=5.5.
Due to molten steel in ingot casting crystallization process selective crystallization and formed chemical composition be in uneven distribution dendrite group
Knit, the large dendritic crystal in ingot casting is elongated in rolling along deformation direction, and gradually consistent with deformation direction, thus formed carbon and
The dilution band and enrichment band of alloying element are alternating with each other to be stacked, under the conditions of slow cooling, is first separated out in carbon and alloying element dilution band
Eutectoid ferrite, and unnecessary carbon is discharged into the enrichment band of both sides, ultimately form the band based on ferrite；And carbon and alloy member
Plain enrichment band forms the band based on pearlite behind, thus form the band based on ferrite with based on pearlite
With banded structure alternating with each other.Component segregation is more serious, and the banded structure of formation is also more serious.Due to banded structure adjacent belts
Microscopic structure it is different, their performance is also differed, with obvious anisotropy.When carrying out side knock experiment, by force
Stress concentration can be produced between weak band, causes side knock performance substantially relatively low.
P280GH steel is the higher carbon steel of manganese content, and ingot casting arborescent structure segregation is more serious, causes its fished pipe
Banded structure rank is high, the side knock performance of steel pipe is remarkably decreased.Therefore, the transverse direction of P280GH thick-walled seamless steel pipes is improved
Impact property, should improve the carbon manganese component segregation of P280GH steel first.
Therefore, second technical problem to be solved by this invention, which is to provide one kind, can be obviously improved steel pipe component segregation
Seamless steel tube for nuclear power preparation method.
A kind of preparation method of seamless steel tube for nuclear power of the present invention, comprises the following steps：
A, smelting casting：Using steel scrap and sponge iron as raw material, melting, tapping, continuous casting obtains continuous casting billet；
The present invention uses high-quality steel scrap and sponge iron for raw material, ultra high electric arc furnace melting can be used, by eccentric stove
Tap at bottom, it is ensured that stay steel to stay slag, slag free tapping；
B, hot rolling tube rolling：The continuous casting billet that a steps are obtained is heated to 1260~1280 DEG C, is incubated 6~7h；Come out of the stove, treat temperature
When degree drops to 1210~1230 DEG C, eleven punch 11 is entered to pipe；Tube rolling is carried out after perforation, finishing temperature is 860~900 DEG C；
According to the specification of fished pipe using the pipe of dimension, it is ensured that lengthening coefficient >=5.5 of steel pipe；To pipe
The implementation on conic perforator can be used by entering eleven punch 11；
C, heat treatment：It is divided into the pre-heat treatment and is heat-treated eventually；
Wherein, the pre-heat treatment is that the steel pipe that is rolled into b step is air-cooled to 300~400 DEG C and enters stove, is heated to 630~650
After DEG C, according to thickness of steel pipe meter, 1.5~2min/mm is incubated；Continue to be heated to 960~980 DEG C, be incubated 6~8h；It is cold with stove again
To 555~565 DEG C, 5~6h is incubated；Finally with being furnace-cooled to after 500 DEG C, come out of the stove and be air-cooled to room temperature；
It is that the good steel pipe of the pre-heat treatment is carried out into normalizing heat treatment to be heat-treated eventually, using pressure cooling side after normalizing heat treatment
Formula；
Wherein, the normalizing temperature of normalizing heat treatment is 890~910 DEG C, according to thickness of steel pipe meter, is incubated 2.5~3min/
mm；
Force cooling to use temperature for 10~50 DEG C of cooling medium, again take out steel pipe after cooling down the of short duration time, in sky
Room temperature is cooled in gas, is produced.
Ladle furnace is whole when melting is refined in a kind of preparation method of seamless steel tube for nuclear power described above, wherein a steps
Argon is stirred, and molten steel is through vacuum outgas and feeds the processing of silicon-aluminium wire, it is ensured that the stabilization of molten steel composition and pure；Using electricity during continuous casting
Magnetic is stirred and soft pressure measure, and control molten steel is poured into a mould under low overheat, to mitigate the component segregation of pipe.
A kind of preparation method of seamless steel tube for nuclear power described above, the cooling medium of the pressure cooling wherein in step c
For 32# machine oil, and as thickness of steel pipe 20mm ＜ D≤30mm, 45~65s is cooled down；During 30mm ＜ D≤40mm, cooling 66~
95s；During 40mm ＜ D≤50mm, 96~126s is cooled down；So, the normalizing cooling rate of P280GH steel pipes can be improved, iron can be obtained again
The metallographic structure of ferritic+pearlite.
The present invention is smelting casting process, is existed when employing continuous casting using electromagnetic agitation and soft pressure measure and control molten steel
The method poured into a mould under low overheat mitigates the component segregation of pipe.
Present inventor has further discovered that, when pipe heating-up temperature be 1300 DEG C, soaking time be 16~18h when, steel
In carbon manganese component segregation will thoroughly be improved, but at the same time can bring that the oxidation and decarbonization and scaling loss of pipe be serious, crystal grain
The problem of abnormal thick, energy resource consumption is big, production cost is high, therefore, in annular furnace heating process, the present invention manages P280GH
The heating-up temperature of base brings up to 1260~1280 DEG C from usually used 1210~1230 DEG C, and soaking time extends to 6 from 3~5h
~7h, by accelerating carbon, the diffusion velocity of manganese and other alloying elements and the method for extending diffusion time so that in P280GH steel
Carbon manganese component segregation obtain a certain degree of improvement, while the oxidation and decarbonization and scaling loss lesser extent of pipe, crystal grain also will not
Abnormal growth.
, must be to pipe to refine the grain size of fished pipe because the heating-up temperature of above-mentioned pipe is higher, soaking time is longer
Base is fully deformed.The present invention employs the pipe of dimension according to the specification of fished pipe, to ensure prolonging for steel pipe
Stretch coefficient >=5.5 so that the deflection of steel pipe disclosure satisfy that the requirement of crystal grain thinning.
The present invention controls the piercing temperature of pipe at 1210~1230 DEG C, becomes by using under relatively low piercing temperature
Shape and finishing temperature control is refined into the crystal grain of fished pipe in 860~900 DEG C of method.
Although this invention takes the measure for the lengthening coefficient, piercing temperature, finishing temperature for controlling steel pipe, due to pipe
Heating-up temperature is higher, soaking time is longer, fished pipe there will still likely be the phenomenon of coarse grains, mixed crystal, therefore, this hair
It is bright that the pre-heat treatment has been carried out before steel pipe final heat treatment.
In the pre-heat treatment, preheated after the P280GH steel pipes for rolling completion are heated into 630~650 DEG C first, with
Reduce the thermal stress in heating process, it is to avoid steel pipe ftractures；Fully it is incubated after being heated to 960~980 DEG C again afterwards, utilizes carbon atom
The principle that diffusion velocity is dramatically speeded up more than 950 DEG C reduces the carbon segregation in steel, while mitigating the manganese segregation in steel；Insulation
Afterwards, 555~565 DEG C of fully insulations are furnace-cooled to, the statenchyma of ferrite+carbide are obtained, so as to cut off original thick crystalline substance
The Structure Inheritance of grain and mixed crystal, has obtained the austenite crystal of fine uniform, meanwhile, the carbon manganese component segregation in steel is also obtained
A certain degree of improvement.
In final normalized treatment, to improve banded structure, the present invention is first by the normalizing soaking time generally used
2.5~3min/mm is brought up to from 1.5~2min/mm, to improve the uniform of alloying elements distribution in normalizing austenitization
Property, by taking the method for mitigation component segregation to improve the banded structure of fished pipe..
Secondly, employ and carry out the method for air cooling after short stay to accelerate normalizing cooling rate in 32# machine oil by steel pipe, make
Overcooling austenite changes at a lower temperature, and carbon can not fully be diffused into carbide former enrichment area, so, not only may be used
To significantly improve its banded structure, but also can be with the size of fining ferrite grains and pearlite colony.
The present invention is from cooling medium of the 32# machine oil as normalized treatment, using the cooling capacity of 32# machine oil substantially compared with water
It is cold poor and be slightly faster than the characteristics of mist is cold.Because P280GH steel is low carbon manganese steel, carbon and alloying element content are low, and quenching degree is poor；
And the size of P280GH thick walled steel tubes is between 20~50mm, thermal capacity is larger.Therefore, when P280GH thick walled steel tube austenites
Can not occur bainite or martensitic traoformation after short stay in immersion 32# machine oil after change, while can realize that quickening normalizing is cold
Speed and the purpose for improving cooling uniformity.In addition, in normalizing procedure, the liquid temperature of 32# machine oil should be controlled at 10~50 DEG C, it is to avoid
Answer high oil temperature and influence the service life of machine oil.
The embodiment of the present invention is further described with reference to embodiment, not therefore by present invention limit
System is among described scope of embodiments.
Embodiment 1
The production of Ф 168.3 × 22 P280GH steel pipes
Smelt casting：
High-quality steel scrap+sponge iron is used for raw material, using ultra high electric arc furnace melting, by eccentric bottom tapping, it is ensured that
Steel is stayed to stay slag, slag free tapping；
Using the whole Argon stirring of ladle furnace during refining, molten steel is through vacuum outgas and feeds silicon-aluminium wire processing, it is ensured that molten steel into
Point stabilization and pure；
Electromagnetic agitation and soft pressure measure are used during continuous casting, control molten steel is poured into a mould under low overheat, to mitigate pipe
Component segregation；
By smelting and continuous casting, Ф 280 continuous casting billet is obtained, the chemical composition of steel billet is shown in Table 1,
The chemical composition of the P280GH steel billets of table 1
| C | Si | Mn | P | S | Cr | Ni | Cu | Mo | Al | Sn |
| 0.136% | 0.28% | 1.05% | 0.012% | 0.0008% | 0.12% | 0.08% | 0.08% | 0.04% | 0.032% | 0.008% |
Tube rolling：
Using Ф 280 continuous casting billet tube rolling, lengthening coefficient is 6.89；
The heating-up temperature of pipe is 1260 DEG C before rolling, and soaking time is 6.5h；
Pipe is come out of the stove and implements to perforate on conic perforator after its temperature is down to 1220 DEG C；
Then tube rolling is carried out on milling train, control finishing temperature is at 860~900 DEG C.
Heat treatment：
1st, the pre-heat treatment
300~400 DEG C are air-cooled to after the completion of P280GH steel pipe rollings and enters stove, is heated to be incubated after 630 DEG C, soaking time is
35min；
Continue to be heated to after insulation to be incubated after 960 DEG C, soaking time is 8h；
After insulation, 560 DEG C of insulations are furnace-cooled to, soaking time is 6h；
Then it is furnace-cooled to come out of the stove after 500 DEG C and is air-cooled to room temperature.
2nd, heat treatment eventually
Steel pipe by the pre-heat treatment carries out final heat treatment, and heat treating regime is heat-treated for normalizing, and step is as follows：
Normalizing temperature is 910 DEG C, and soaking time is 66min；
Cooling is by the way of cooling is forced, and specific method is：
Cooling medium uses 32# machine oil, and liquid temperature controls temperature to be 10~50 DEG C.
Steel pipe is immersed in cooling medium after 45s, then taken out from cooling medium, and is cooled to room temperature in atmosphere.
Steel tube performance is detected:
The performance test results of Ф 168.3 × 22 P280GH steel pipes are shown in Table 2~table 3, and accompanying drawing 1 is shown in metallographic structure.Wherein,
The test stone of non-metallic inclusion is GB/T10561, and the test stone of banded structure is GB/T 13299, the inspection of grain size
Standard is GB/T 6394.
The non-metallic inclusion of table 2, grain size and metallographic structure situation
The mechanical property of the seamless steel pipe of table 3
Embodiment 2
The production of Ф 457 × 37 P280GH steel pipes
Smelt casting：
High-quality steel scrap+sponge iron is used for raw material, using ultra high electric arc furnace melting, by eccentric bottom tapping, it is ensured that
Steel is stayed to stay slag, slag free tapping；
Using the whole Argon stirring of ladle furnace during refining, molten steel is through vacuum outgas and feeds silicon-aluminium wire processing, it is ensured that molten steel into
Point stabilization and pure；
Electromagnetic agitation and soft pressure measure are used during continuous casting, control molten steel is poured into a mould under low overheat, to mitigate pipe
Component segregation；
By smelting and continuous casting, Ф 620 continuous casting billet is obtained, the chemical composition of steel billet is shown in Table 4,
The chemical composition of the P280GH steel billets of table 4
| C | Si | Mn | P | S | Cr | Ni | Cu | Mo | Al | Sn |
| 0.128% | 0.32% | 0.98% | 0.011% | 0.0006% | 0.15% | 0.09% | 0.08% | 0.04% | 0.035% | 0.007% |
Tube rolling：
Using Ф 620 continuous casting billet tube rolling, lengthening coefficient is 5.97；
The heating-up temperature of pipe is 1280 DEG C before rolling, and soaking time is 7h；
Pipe is come out of the stove and implements to perforate on conic perforator after its temperature is down to 1220 DEG C；
Then tube rolling is carried out on milling train, control finishing temperature is at 860-900 DEG C.
Heat treatment：
1st, the pre-heat treatment
300~400 DEG C are air-cooled to after the completion of P280GH steel pipe rollings and enters stove, is heated to be incubated after 630 DEG C, soaking time is
65min；
Continue to be heated to after insulation to be incubated after 980 DEG C, soaking time is 8h；
After insulation, 565 DEG C of insulations are furnace-cooled to, soaking time is 6h；
Then it is furnace-cooled to come out of the stove after 500 DEG C and is air-cooled to room temperature.
2nd, final heat treatment
Steel pipe by the pre-heat treatment carries out final heat treatment, and heat treating regime is heat-treated for normalizing, and step is as follows：
Normalizing temperature is 890 DEG C, and soaking time is 100min；
Cooling is by the way of cooling is forced, and specific method is：
Cooling medium uses 32# machine oil, and liquid temperature controls temperature to be 10~50 DEG C.
Steel pipe is immersed in cooling medium after 92s, then taken out from cooling medium, and is cooled to room temperature in atmosphere.
Steel tube performance is detected
The performance test results of Ф 457 × 37 P280GH steel pipes are shown in Table 5~table 6, and accompanying drawing 2 is shown in metallographic structure.
Wherein, the test stone of non-metallic inclusion is GB/T10561, and the test stone of banded structure is GB/T
13299, the test stone of grain size is GB/T6394.
The non-metallic inclusion of table 5, grain size and metallographic structure situation
The mechanical property of the seamless steel pipe of table 6
Claims (2)
1. a kind of preparation method of seamless steel tube for nuclear power, it is characterised in that：Comprise the following steps：
A, smelting casting：Using steel scrap and sponge iron as raw material, melting, tapping, continuous casting obtains continuous casting billet；
Wherein, ladle furnace whole Argon stirring when melting is refined, molten steel is through vacuum outgas and feeds silicon-aluminium wire processing；Adopted during continuous casting
With electromagnetic agitation and soft pressure measure；
The continuous casting billet is made up of following weight percent composition：C 0.128~0.136%, Si 0.28~0.32%, Mn
0.98~1.05%, P≤0.012%, S≤0.0008%, Cr≤0.15%, Ni≤0.09%, Mo≤0.04%, Cu≤
0.08%th, Al 0.032~0.035%, Sn≤0.008%, surplus is Fe；
B, hot rolling tube rolling：The continuous casting billet that a steps are obtained is heated to 1260~1280 DEG C, is incubated 6~7h；Come out of the stove, treat that temperature drops
During to 1210~1230 DEG C, eleven punch 11 is entered to pipe；Tube rolling is carried out after perforation, finishing temperature is 860~900 DEG C；
C, heat treatment：It is divided into the pre-heat treatment and is heat-treated eventually；
Wherein, the pre-heat treatment is that the steel pipe that is rolled into b step is air-cooled to 300~400 DEG C and enters stove, is heated to 630~650 DEG C
Afterwards, according to thickness of steel pipe meter, it is incubated 1.5~2min/mm；Continue to be heated to 960~980 DEG C, be incubated 6~8h；Again with being furnace-cooled to
555~565 DEG C, it is incubated 5~6h；Finally with being furnace-cooled to after 500 DEG C, come out of the stove and be air-cooled to room temperature；
It is that the good steel pipe of the pre-heat treatment is carried out into normalizing heat treatment to be heat-treated eventually, using the pressure type of cooling after normalizing heat treatment；
Wherein, the normalizing temperature of normalizing heat treatment is 890~910 DEG C, according to thickness of steel pipe meter, is incubated 2.5~3min/mm；
Force cooling to use temperature for 10~50 DEG C of cooling medium, again take out steel pipe after cooling down the of short duration time, in atmosphere
Room temperature is cooled to, is produced.
2. a kind of preparation method of seamless steel tube for nuclear power according to claim 1, it is characterised in that：Pressure in step c
The cooling medium of cooling is 32# machine oil, and as thickness of steel pipe 20mm ＜ D≤30mm, cools down 45~65s；30mm ＜ D≤40mm
When, cool down 66~95s；During 40mm ＜ D≤50mm, 96~126s is cooled down.
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