A kind of centrifugal cast cannulation and preparation technology thereof
Technical field
The invention belongs to centrifugal casting alloy furnace tubes by adopting technical field, be specifically related to a kind of centrifugal cast cannulation and
Its preparation technology.
Background technology
In China, centrifugal casting furnace tube gradually domesticizes in 20 century 70s, experienced by nearly 20
Year just forms certain production scale.At petrochemical industry, high-alloy centrifugal casting boiler tube is by extensively
As reburner and the boiler tube of pyrolysis furnace, such as Nanjing Refinery, the hydrogen manufacturing conversion furnace of Zhenghai general petrochemicals factory,
The pyrolysis furnace etc. of Yanshan Petrochemical company.
Centrifugal casting alloy furnace tubes by adopting gradually develops to high parameter and maximization direction in recent years, and military service operating mode is more
Add complexity and harshness, thus the performance requirement of the domestic centrifugal casting alloy furnace tubes by adopting come into operation on market is also got over
Coming the highest, use the boiler tube that conventional preparation techniques produces is not well positioned to meet Production requirement, loses efficacy
Accident happens occasionally, and brings very big hidden danger to the long period safe operation of petrochemical industry device for producing hydrogen.Stove
Pipe once lost efficacy, and will have a strong impact on the long period safe operation of package unit.
Additionally, high temperature furnace pipe factory generally uses intermediate frequency furnace smelting process, this technique purification capacity is poor,
Require high for the raw material selected by metallurgy.In boiler tube manufacturing, in order to reduce production cost,
The old boiler tube that generally existence recovery petroleum chemical enterprise scraps mixes the phenomenon refining new boiler tube.Adding old boiler tube smelting
During refining, the low-melting impurities that old boiler tube tube wall remains may be brought in the boiler tube of coming of new,
During boiler tube Long-term Service under High Temperature, impurity element can reduce in boiler tube Grain Boundary Segregation, embrittlement of grain boundaries
The creep-resistant property of furnace tube material, causes boiler tube service life to be greatly shortened.
Therefore, those skilled in the art need a kind of spun casting with excellent high temperature mechanical property of offer badly
Boiler tube and preparation technology thereof.
Summary of the invention
For above-mentioned deficiency, the invention provides a kind of centrifugal cast cannulation and preparation technology thereof.The present invention
The centrifugal cast cannulation that mechanical behavior under high temperature is excellent can not only be prepared, and its preparation technology also keeps away
Exempt from the embrittlement of grain boundaries that impurity element causes at boiler tube Grain Boundary Segregation, improve the service life of boiler tube.
A kind of centrifugal cast cannulation is provided one of for achieving the above object, present invention employs techniques below side
Case:
A kind of centrifugal cast cannulation, this furnace tube material, in units of mass percent, comprises following content
Component:
The two of the purpose of the present invention are to provide the preparation technology of a kind of above-mentioned centrifugal cast cannulation, including as follows
Step:
S1, to close in the middle of steel scrap, ferromanganese and ferrosilicon, ferrochrome, pure nickel, molybdenum-iron and rare earth nickel gadolinium, nickel cerium
Gold is raw material, and according to the mass percent of described each component, calculate and weigh each raw material, joins
Material;
S2, above-mentioned raw material is melted in electric furnace, and through three aluminium wire deoxidations in fusion process,
Remove the gred at liquid steel level for twice, then stand and obtain molten state molten steel;
S3, according to formula N=20 × (G/r)1/2, calculate the centrifugal rotational speed of the steel pipe die cavity of centrifugal casting.
Wherein N is the centrifugal rotational speed of die cavity, and r is steel pipe inside radius, and G is steel pipe gravity coefficient, G take 47~
80, the steel pipe G-value of centrifugal casting is determined by the following manner: steel pipe G minimum for phosphorus content is taken 80, contains
The steel pipe G that carbon amounts is the highest takes 47, thereby determines that out the linear graph between steel pipe carbon content and G, and is centrifuged
The steel pipe G-value of casting is determined by linear scale by this linear graph;
S4, when die cavity turns to calculated centrifugal rotational speed, by steel ladle pour steel in die cavity,
Casting process uses argon guarantee molten steel not oxidized, pours into a mould about 5~10 minutes;
S5, the rear demoulding of above-mentioned steps, be cooled to room temperature by centrifugal steel pipe, according to measuring its sulfur included
With the content of oxygen, removed the impurity of internal surface of steel pipe layer by interior boring machining process.
Further, in step S2, three aluminium wire deoxidations, twice step bag in liquid steel level slagging-off
Include:
S20, steel scrap is added in electric furnace heat fusing, after molten steel is melting down, be sequentially added into ferromanganese and ferrosilicon
Melting down, and carry out aluminium wire deoxidation for the first time;
It is sequentially added into pure nickel, molybdenum-iron, ferrochrome after S21, aluminium wire deoxidation for the first time, then carries out the second secondary aluminium
Silk deoxidation, and remove the gred at liquid steel level;
S22, be sequentially added into rare earth nickel gadolinium, nickel cerium intermediate alloy subsequently, be again with aluminium wire deoxidation and
Liquid steel level removes the gred and stands and obtains molten state molten steel.
Further, in step S4, pouring temperature is 1523~1573 DEG C.
Further, the impurity of interior boring internal surface of steel pipe layer in step S5, until the steel pipe inner wall after interior boring
Sulfur content≤0.020%, oxygen content≤12ppm.
The beneficial effects of the present invention is:
1), in each composition of centrifugal cast cannulation of the present invention, in composition containing 1.0~the gadolinium of 2.50% and
0.20~the cerium of 0.40%.The existence of gadolinium element, on the one hand hinders growing up of crystal grain at grain boundary sites,
Serve Grain refinement, improve the comprehensive mechanical property of alloy;On the other hand, at process of setting
Middle gadolinium is preferentially forming mechanical behavior under high temperature excellent Ni-Gd intermetallic compound at grain boundaries with nickel, and will
Crystal grain wraps up, and makes the mechanical behavior under high temperature of alloy obtain the lifting of matter.The existence of a small amount of Ce elements,
On the one hand Ce elements hinders growing up of crystal grain at grain boundary sites, serves Grain refinement, improves
The comprehensive mechanical property of alloy;On the other hand, cerium can make impurity content in molten steel reduce with cleaning molten steel,
Improve its mechanical property.
2), the present invention is with nickel gadolinium and nickel cerium intermediate alloy form at preparation technology rare earth elements gadolinium and cerium
Add, on the one hand can reduce rare earth element scaling loss during high melt in a large number;On the other hand,
Nickel gadolinium intermediate alloy after fusing can at high operating temperatures can be with Ni-Gd intermetallic compound and at crystal boundary
Place preserves.
3), in preparation technology of the present invention, use aluminium wire deoxidation for three times, and twice removed the gred at liquid steel level,
Reduce further the impurity content of molten steel, it is ensured that the mechanical behavior under high temperature of boiler tube;And in spun casting
During, according to formula N=20 × (G/r)1/2Calculate the centrifugal rotational speed of the tubing die cavity of centrifugal casting,
Under this rotating speed, field trash can concentrate the inner surface being distributed in steel pipe, can be effectively reduced steel duct and occur
Inclusion content;In die cavity, during pour steel, use air seal protection in steel ladle simultaneously,
By pouring molten steel in die cavity, it is possible to prevent molten steel to be oxidized by oxygen.
4), in preparation technology of the present invention, pouring temperature is about 1523~1573 DEG C, the duration of pouring be 5~
About 10 minutes.This pouring temperature and time, on the one hand can ensure that the mobility of molten steel, reduce molten steel
Because of the long-time oxidational losses exposing and producing;On the other hand, nickel gadolinium intermediate alloy at this temperature can be preferential
Separate out, add the nucleation rate of alloy, reduce the grain size of alloy, also promote nickel gadolinium intermediate alloy
There is enough time crystallite-cladded along crystal boundary.
5), the present invention remove internal layer field trash by interior boring machining, make that steel pipe forming speed is fast, add
Work flow process reduces, and recovery rate of iron is high.
Accompanying drawing explanation
Fig. 1 is the SEM figure of centrifugal cast cannulation of the present invention.
Fig. 2 is gravity coefficient of the present invention-carbon content linear relationship chart.
Detailed description of the invention
Below in conjunction with accompanying drawing, the technical scheme in the present invention is clearly and completely described.Below
Embodiment is only used for clearly illustrating technical scheme, and can not limit the present invention with this
Protection domain.
The steel pipe G-value of centrifugal casting in the present invention is determined by the following manner: by steel pipe G minimum for phosphorus content
Taking 80, the steel pipe G that phosphorus content is the highest takes 47, and thereby determine that out between steel pipe carbon content and G is linear
Figure, and the steel pipe G-value of centrifugal casting is determined by linear scale by this linear graph.
Embodiment 1
The tubing of centrifugal casting a size of Φ 550/350 × 2000mm, its casting method is
(1), determine furnace tube material composition and by mass percentage (wt%) carry out batching weighing:
(2) steel scrap is heated in electric furnace about 1500 DEG C fusings, after molten steel is melting down, adds successively
Enter ferromanganese and ferrosilicon is melting down, and after using aluminium wire deoxidation, after sequentially adding pure nickel, molybdenum-iron, ferrochrome,
It is again with aluminium wire deoxidation and after liquid steel level removes the gred, is sequentially added into subsequently in the middle of rare earth nickel gadolinium, nickel cerium
Alloy, is again with aluminium wire deoxidation and removes the gred at liquid steel level and stand and obtain molten state molten steel;
(3) according to formula N=20 × (G/r)1/2, calculate the centrifugal rotational speed of the tubing die cavity of centrifugal casting.
Wherein N is the centrifugal rotational speed of die cavity, and r is steel pipe inside radius, and G is steel pipe gravity coefficient, G take 47~
80.First calculate carbon equivalent Ceq=0.282 of steel pipe, calculate G according to Fig. 2 in proportion and take 80,
Internal surface of pipe radius, in view of the allowance of 10mm, takes r=0.165m, and calculating centrifugal rotational speed is
378r/min。
(4) when die cavity turns to calculated centrifugal rotational speed, by steel ladle pour steel in die cavity,
Casting process use argon to ensure molten steel is not oxidized, pouring temperature is about 1523 DEG C, and the duration of pouring is
About 5 minutes;
(5) rear demoulding of above-mentioned steps, is cooled to room temperature by centrifugal steel pipe, now measures in this steel pipe
Surface sulfur 0.04%, oxygen content is 28ppm, removes steel pipe base endosexine by interior boring machining process
Impurity, the sulfur content 0.018% now recorded, oxygen content 12ppm, prepare centrifugal cast cannulation, SEM
Figure is as shown in Figure 1.
Embodiment 2: the tubing of centrifugal casting a size of Φ 460/350 × 2000mm, its casting method is
(1) determine furnace tube material composition and by mass percentage (wt%) carry out batching weighing:
(2) steel scrap is heated in electric furnace about 1500 DEG C fusings, after molten steel is melting down, adds successively
Enter ferromanganese and ferrosilicon is melting down, and after using aluminium wire deoxidation, after sequentially adding pure nickel, molybdenum-iron, ferrochrome,
It is again with aluminium wire deoxidation and after liquid steel level removes the gred, is sequentially added into subsequently in the middle of rare earth nickel gadolinium, nickel cerium
Alloy, is again with aluminium wire deoxidation and removes the gred at liquid steel level and stand and obtain molten state molten steel;
(3) according to formula N=20 × (G/r)1/2, calculate the centrifugal rotational speed of the tubing die cavity of centrifugal casting.
Wherein N is the centrifugal rotational speed of die cavity, and r is steel pipe inside radius, and G is steel pipe gravity coefficient, G take 47~
80, the steel pipe G-value of centrifugal casting is determined by linear scale by carbon content relation in material.The carbon of steel pipe is worked as
Amount Ceq=0.398, calculates G according to ratio and takes 62, and internal surface of pipe radius is in view of the processing of 10mm
Surplus, takes r=0.130m, and calculating centrifugal rotational speed is 437r/min;
(4) when die cavity turns to calculated centrifugal rotational speed, by steel ladle pour steel in die cavity,
Casting process use argon to ensure molten steel is not oxidized, pouring temperature is about 1550 DEG C, and the duration of pouring is
About 7 minutes;
(5) rear demoulding of above-mentioned steps, is cooled to room temperature by centrifugal steel pipe, now measures in this steel pipe
Surface sulfur 0.035%, oxygen content is 25ppm, by table in interior boring machining process removal steel pipe base
Layer impurity, the sulfur content 0.019% now recorded, oxygen content 11ppm, prepare centrifugal cast cannulation.
Embodiment 3: the tubing of centrifugal casting a size of Φ 420/240 × 2000mm, its casting method is
((1) determine furnace tube material composition and by mass percentage (wt%) carry out batching weighing:
(2) steel scrap is heated in electric furnace about 1500 DEG C fusings, after molten steel is melting down, adds successively
Enter ferromanganese and ferrosilicon is melting down, and after using aluminium wire deoxidation, after sequentially adding pure nickel, molybdenum-iron, ferrochrome,
It is again with aluminium wire deoxidation and after liquid steel level removes the gred, is sequentially added into subsequently in the middle of rare earth nickel gadolinium, nickel cerium
Alloy, is again with aluminium wire deoxidation and removes the gred at liquid steel level and stand and obtain molten state molten steel;
(3) according to formula N=20 × (G/r)1/2, calculate the centrifugal rotational speed of the tubing die cavity of centrifugal casting.
Wherein N is the centrifugal rotational speed of die cavity, and r is steel pipe inside radius, and G is steel pipe gravity coefficient, G take 47~
80, the steel pipe G-value of centrifugal casting is determined by linear scale by carbon content relation in material.The carbon of steel pipe is worked as
Amount Ceq=0.55, calculates G according to ratio in Fig. 2 and takes 47, and internal surface of pipe radius considers 10mm
Allowance, take r=0.110m, calculating centrifugal rotational speed is 515r/min;
(4) when die cavity turns to calculated centrifugal rotational speed, by steel ladle pour steel in die cavity,
Casting process use argon to ensure molten steel is not oxidized, pouring temperature is about 1573 DEG C, and the duration of pouring is
About 10 minutes;
(5) rear demoulding of above-mentioned steps, is cooled to room temperature by centrifugal steel pipe, now measures in this steel pipe
Surface sulfur 0.039%, oxygen content is 27ppm, by table in interior boring machining process removal steel pipe base
Layer impurity, the sulfur content 0.019% now recorded, oxygen content 12ppm, prepare centrifugal cast cannulation.
Through the centrifugal cast cannulation mechanical behavior under high temperature Data Comparison that above-mentioned manufacture method obtains:
Table 1 deep-sea oil recovery equipment valve seat steel forgings comprehensive mechanics Data Comparison
As shown in Table 1, above-mentioned 3 embodiment products are respectively provided with the mechanical behavior under high temperature of excellence, can be very well
Ground is applicable to petrochemical industry.
The above is only the preferred embodiment of the present invention, it is noted that general for the art
For logical technical staff, on the premise of without departing from the technology of the present invention principle, it is also possible to make some improvement
And deformation, these improve and deformation also should be regarded as protection scope of the present invention.