CN107557616B - Nickel-based corrosion-resistant alloy pipe and manufacturing method thereof - Google Patents

Nickel-based corrosion-resistant alloy pipe and manufacturing method thereof Download PDF

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CN107557616B
CN107557616B CN201710887676.0A CN201710887676A CN107557616B CN 107557616 B CN107557616 B CN 107557616B CN 201710887676 A CN201710887676 A CN 201710887676A CN 107557616 B CN107557616 B CN 107557616B
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nickel
resistant alloy
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CN107557616A (en
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欧新哲
黄妍凭
马明娟
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Baowu Special Metallurgy Co Ltd
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Baowu Special Metallurgy Co Ltd
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Abstract

A nickel-based corrosion resistant alloy pipe for a high temperature gas cooled reactor steam generator and a manufacturing method thereof are disclosed, wherein the pipe comprises the following components in percentage by weight: 0.03-0.04% of C, less than or equal to 0.010% of P, less than or equal to 0.010% of S, 20.0-23.0% of Cr, more than or equal to 58.0% of Ni, Mo: 8.5-9.5%, Nb: 3.3-3.8%, Al: 0.35-0.60%, Ti: 0.35-0.60%, Mg: 0.002-0.005%, Fe: 3.0-5.0%, Al + Ti: 0.90-1.0%, and the balance of inevitable impurities. The pipe has uniform tissue, 3-5 grade grain size, room-temperature tensile strength of more than or equal to 700MPa, yield strength of more than or equal to 300MPa and elongation of more than or equal to 40 percent; the high-temperature strength at 750 ℃ is more than or equal to 500MPa, the yield strength is more than or equal to 210MPa, and the elongation is more than or equal to 90 percent; flattening until the distance between the inner walls is 2 times of the wall thickness, and no crack is formed on the sample after flattening; the water leakage or sweating phenomenon can not be caused when the pipes are subjected to a 20MPa hydrostatic test one by one; the pipes are subjected to liquid permeation inspection one by one, the surface is not allowed to have permeation defects, and the pipe is extrapolated by 10 degrees at 750 DEG C5The hour endurance strength is more than or equal to 75.3MPa, and the manufacturing requirement of the high-temperature gas cooled reactor steam generator is met.

Description

Nickel-based corrosion-resistant alloy pipe and manufacturing method thereof
Technical Field
The invention belongs to the technical field of nickel-based corrosion-resistant alloy seamless pipe processing, and particularly relates to a nickel-based corrosion-resistant alloy pipe for a high-temperature gas cooled reactor steam generator and a manufacturing method thereof.
Background
Nuclear power is advanced clean energy, is an important component of the national energy strategy, and is one of the most important measures for realizing the national energy-saving and emission-reducing targets. The modular high-temperature gas cooled reactor nuclear power station has the characteristics of high safety, simple system, high power generation efficiency, wide application, economic competitiveness and the like, and is one of the fourth generation advanced nuclear reactor types required by the future energy market. The helium temperature at the inlet of a steam generator in a high-temperature gas cooled reactor nuclear power station reaches 750 ℃, so that the long-term working temperature of parts in a steam generator inlet chamber and a heat exchange assembly also reaches 750 ℃, the manufacturing of the parts puts severe requirements on the room temperature performance, 750 ℃ instantaneous performance, 750 ℃ durability, tissue stability, corrosion performance and the like of materials, and common austenitic stainless steel and nickel-based alloy cannot meet the use requirements.
The UNS N06625 nickel-based corrosion-resistant alloy is one of main candidate materials for manufacturing the high-temperature gas-cooled reactor steam generator, is a Ni-Cr-Mo solid solution strengthening type nickel-based corrosion-resistant alloy with higher Mo content, not only contains higher Cr and Ni elements, but also has higher Mo and Nb elements, so that the UNS N06625 alloying degree is higher, if a conventional seamless pipe processing method is adopted, the difficulty is quite high from the process aspects of smelting, hot processing, cold processing and heat treatment of the pipe, and particularly the difficulty is higher when the UNS N06625 alloy pipe meeting the manufacturing requirements of the high-temperature gas-cooled reactor steam generator is manufactured.
Disclosure of Invention
The invention aims to provide a nickel-based corrosion-resistant alloy pipe for a high-temperature gas cooled reactor steam generator and a manufacturing method thereof, wherein the tensile strength at room temperature of the alloy pipe is more than or equal to 700MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 40 percent; the high-temperature strength at 750 ℃ is more than or equal to 500MPa, the yield strength is more than or equal to 210MPa, and the elongation is more than or equal to 90 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is more than or equal to 75.3MPa, and the method is suitable for manufacturing a high-temperature gas cooled reactor steam generator.
In order to achieve the purpose, the invention adopts the following technical scheme:
a nickel-based corrosion-resistant alloy pipe for a high-temperature gas cooled reactor steam generator comprises the following chemical components in percentage by weight: c: 0.03-0.04%, P is less than or equal to 0.010%, S is less than or equal to 0.010%, Cr: 20.0-23.0%, Ni is more than or equal to 58.0%, Mo: 8.5-9.5%, Nb: 3.3-3.8%, Al: 0.35-0.60%, Ti: 0.35-0.60%, Mg: 0.002-0.005%, Fe: 3.0-5.0%, and the above elements also need to satisfy the following relational expression: al + Ti: 0.90-1.0%, and the balance of inevitable impurities.
Preferably, the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator further comprises the following chemical components: more than 0 and less than or equal to 0.3 percent of Si, more than 0 and less than or equal to 0.50 percent of Mn, more than 0 and less than or equal to 0.20 percent of Cu, and more than 0 and less than or equal to 0.08 percent of Co.
Furthermore, the microstructure of the nickel-based corrosion-resistant alloy pipe is equiaxial crystal, and the grain size is 3-5 grade.
Then, the tensile strength at room temperature of the nickel-based corrosion-resistant alloy pipe is more than or equal to 700MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 40%; the high-temperature strength at 750 ℃ is more than or equal to 500MPa, the yield strength is more than or equal to 210MPa, and the elongation is more than or equal to 90 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is more than or equal to 75.3 MPa.
In the composition design of the pipe of the invention:
c: element C is an important alloying element that strongly forms, stabilizes and expands austenite. On the one hand, C element is easy to form Cr carbide with Cr in the alloy, which easily causes the problem of intergranular corrosion of the alloy, and the pipe in the high-temperature gas cooled reactor is not allowed to generate intergranular corrosion defects, so that the C content in the alloy is not easy to be too high. On the other hand, the C element is an important alloy element for interstitial solid solution strengthening, and the pipe in the high-temperature gas-cooled reactor has special requirements on the high-temperature strength and the endurance strength of the alloy at 750 ℃, so that the C content cannot be too low. Therefore, the content of C is controlled to be 0.03-0.04%.
Mo: mo element can improve the solid solution strength of the alloy, but Mo element is also an element easy to segregate, and can promote the precipitation of intermetallic harmful phases, so that the plasticity of the alloy is reduced, and the addition is not high easily. The content of Mo is controlled to be 8.5-9.5%.
Nb: nb is an important solid solution strengthening element in the nickel-based alloy, but Nb is also an easily segregated element, too much Nb is easy to form a Laves phase with a lower melting point, the hot workability of the alloy is reduced, and the strengthening effect is not ideal if the Nb content is too low. Therefore, the content of Nb is controlled to be 3.3-3.8%.
Al and Ti: al and Ti mainly affect alloy dislocation and form Ni with Ni3The (Al, Ti) strengthening phase improves the alloy strength. The invention promotes the alloy to form Ni by controlling the total addition amount of Al and Ti3Strengthening phase (Al and Ti), pinning dislocation, controlling growth of alloy crystal grain size, and improving high temperature instantaneous strength at 750 deg.C and high temperature permanent strength at 750 deg.C. On the other hand, Al and Ti have high chemical activity, the addition amount of Al and Ti is too high, Al and Ti are easy to form brittle compounds with C, N, O and S during welding, and welding is causedThe welding crack is generated, the welding performance of the material is reduced, and meanwhile, the Al and Ti are easy to burn during smelting. In order to improve the comprehensive performance of the alloy, the invention controls the ratio of Al: 0.35-0.60%, Ti: 0.35-0.60%, and the total amount of Al and Ti is in the range of 0.90-1.0%.
Mg: the proper amount of Mg alloy is added, the main functions are to purify crystal boundary and enhance the long-term creep resistance of the alloy at high temperature, but excessive Mg can generate Mg brittle inclusion to influence the plasticity of the alloy. Therefore, the content of Mg is controlled to be 0.002-0.005%.
Co: co element is activated and radioactive in the irradiation environment of a nuclear electric field, and can be precipitated in nuclear power systems such as pipelines and valves, so that the pipelines and valves also have radioactivity, the normal operation of the nuclear power station can be influenced, and Co is controlled to be less than or equal to 0.08%.
Cr: the Cr element can improve the oxidation resistance of the alloy in a high-temperature environment to generate a passivation effect, and meanwhile, the higher Cr can improve the overall corrosion resistance and the local corrosion resistance of the alloy. However, with the increase of the Cr content, the structural stability of the alloy is reduced, a brittle intermetallic phase is easily formed in the structure, and the processing and use performances of the alloy are reduced. Therefore, the Cr content is controlled to be 20.0-23.0%.
Si: si element is an element that strongly forms a brittle intermetallic sigma phase, and reduces hot and cold workability of the alloy. Therefore, the content of Si is controlled to be less than or equal to 0.3 percent.
Mn: the Mn element has the effect of enlarging the austenite structure of the alloy, can replace partial nickel, improves the structure stability, reduces the cost of the alloy, but easily forms MnS and other low-melting-point harmful substances due to too high Mn content, and reduces the hot-working performance of the material. Therefore, the Mn content is controlled to be less than or equal to 0.5 percent.
Cu: the Cu element in the alloy is controlled as an inevitable impurity element, and the Cu content is specifically controlled to be less than or equal to 0.20%.
Fe: the Fe content is increased in the alloy mainly for reducing the alloy cost, and the Fe content is specifically controlled to be 3.0-5.0%.
The invention provides a method for manufacturing a nickel-based corrosion-resistant alloy pipe for a high-temperature gas cooled reactor steam generator, which comprises the following steps:
1) smelting and forging
Smelting and casting the components according to the proportion of the chemical components to form an ingot, and forging the ingot to form an intermediate round pipe blank, wherein the deformation in the forging process is 20-50%;
2) hot extruding the middle round pipe blank into a hollow billet
Preheating the intermediate round pipe blank obtained in the step 1) to 1000-1050 ℃ and preserving heat, and then heating to 1200-1230 ℃ and preserving heat; then, hot extruding to obtain a tubular billet, and cooling the tubular billet to room temperature by water, wherein the temperature of the middle round tube billet in the hot extrusion process is 1180-1200 ℃, the extrusion ratio is 2-20, and the extrusion speed is 100-200 mm/s; finally, removing oxide skin of the tubular billet to obtain the tubular billet with a defect-free surface;
3) cold working
Cold rolling or expanding and drawing the tubular billet obtained in the step 2), wherein the deformation of a cold rolling pass is 30-60% or the deformation of an expanding and drawing pass is 10-20%; if the cold rolling or drawing passes are more than two times, carrying out solid solution treatment and oxide skin removal between adjacent cold rolling or drawing passes, wherein the temperature of the solid solution treatment is 1100-1200 ℃; if the cold rolling or the expanding drawing pass is one time, directly carrying out subsequent processing;
4) performing solution treatment on the finished pipe, wherein the temperature of the solution treatment is 1100-1200 ℃;
5) and (5) surface treatment of the finished pipe.
Preferably, in the step 1), the forging process to form the intermediate circular tube blank is as follows: heating the smelted cast ingot, forging the cast ingot to an intermediate specification by using a quick forging press with the deformation of 20-50%, then reheating, finally forging the cast ingot to a black forged rod by using a radial forging machine, and turning and polishing the cast ingot to form the intermediate round pipe blank after air cooling.
Preferably, in the step 1), the surface finish Ra of the obtained intermediate round pipe blank is less than or equal to 1.6 μm.
Preferably, in the step 2), the heat preservation time of the preheated intermediate circular tube blank is 0.5-1.5 minutes for each millimeter of blank heat preservation.
Preferably, in the step 2), the heat preservation time of the heated intermediate circular tube blank is 1-3 minutes for each centimeter of thickness of the blank.
Preferably, in the step 2), during hot extrusion, the lubricant is uniformly coated on the inner surface and the outer surface of the heated intermediate circular tube blank, the lubricant is coated on the inner wall of the extrusion cylinder of the die, and the intermediate circular tube blank coated with the lubricant is placed into the extrusion cylinder to be hot-extruded into the hollow billet.
More preferably, the lubricant is a glass lubricant.
Preferably, in the step 2) and the step 3), when removing the oxide skin, the pipe is soaked in a mixed aqueous solution of hydrofluoric acid and nitric acid for 40-50 min to remove the oxide skin, then high-pressure water washing is carried out, and the surface folding, cracks and pits of the pipe are polished. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of the hydrofluoric acid is 5-8%, and the weight percentage concentration of the nitric acid is 10-15%.
Preferably, in step 5), the surface treatment of the finished pipe comprises the following steps: the method comprises the steps of soaking a pipe in a mixed aqueous solution of hydrofluoric acid and nitric acid for 40-50 min to remove oxide skin, then washing with high-pressure water, and grinding folds, cracks and pits on the surface of the pipe. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of the hydrofluoric acid is 5-8%, and the weight percentage concentration of the nitric acid is 10-15%.
In the step 1), the forging deformation amount of the tube blank is controlled to be 20-50%, so that the complete crushing of a coarse structure of an ingot can be ensured, the structure density and the structure uniformity of the tube blank are improved, and the material plasticity is improved.
The step type heating mode that the middle round pipe blank is preheated to 1000-1050 ℃ and then is subjected to heat preservation, and then is subjected to induction heating to 1200-1230 ℃ and is subjected to heat preservation is adopted in the step 2), so that the temperature of the pipe blank from the outer surface to the inner surface can be ensured to be uniform, and meanwhile, the low-temperature preheating and high-temperature heating modes can reduce the generation of oxide skin on the surface of the pipe blank and improve the surface quality of the extruded pipe.
In the step 2), the extrusion ratio is controlled to be 2-20 in the pipe extrusion process, so that the complete dispersion and uniformity of the pipe blank tissues in the extrusion process are ensured; the extrusion speed is controlled to be 100-200 mm/s, and the stability of the temperature of the pipe blank in the extrusion process can be ensured.
The alloy provided by the invention has high room temperature strength, severe material work hardening rate tendency and limited cold deformation capacity, and needs multi-pass cold working forming. In order to realize excellent cold forming, structure and size of products and reduce damage to equipment, the deformation of a cold rolling pass of the pipe is controlled to be 30-60% or the deformation of a drawing pass is controlled to be 10-20%.
The solid solution treatment temperature of the pipe finished product in the step 4) is 1100-1200 ℃, the tissue uniformity can be realized, and the high requirement of the nuclear power of the high-temperature gas cooled reactor on the tissue performance is met.
The invention gradually controls the uniformity of the tube structure by optimizing the components and controlling the deformation in the forging process, the extrusion ratio and the extrusion speed in the hot extrusion process, the deformation in the cold rolling process, the matched heat treatment process and the heat treatment on the finished product, thereby ensuring the requirements of uniform tube structure and high performance. The microstructure of the pipe manufactured by the invention is isometric crystal, the grain size is 3-5 grade, the tensile strength at room temperature is more than or equal to 700MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 40 percent; the high-temperature strength at 750 ℃ is more than or equal to 500MPa, the yield strength is more than or equal to 210MPa, and the elongation is more than or equal to 90 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is more than or equal to 75.3 MPa; flattening until the distance between the inner walls is 2 times of the wall thickness, and no crack exists on the sample after flattening; the pipes are subjected to a 20MPa hydrostatic test one by one without water leakage or sweating; the pipe is subjected to liquid permeation inspection one by one, the surface of the pipe does not have permeation defects, the pipe has excellent comprehensive performance, and the manufacturing requirement of a high-temperature gas cooled reactor steam generator is met.
The invention has the beneficial effects that:
1. in the aspect of chemical components, the invention optimizes the content of elements such as C, Mo, Nb and the like, improves the content of Al and Ti, strictly controls the content of Al and Ti within the range of 0.90-1.0%, and simultaneously adds Mg element, thereby greatly improving the uniformity of the tube structure and meeting the requirement of high comprehensive performance of the high-temperature gas cooled reactor on the material.
2. The method comprises the steps of smelting steel ingots, cogging the steel ingots and controlling the forging deformation amount to be 20-50%, so that the gross structure of the steel ingots is completely crushed, round tube blanks with uniform structures are produced, the material plasticity is increased, and the energy consumption has been saved; then, producing a capillary by adopting a hot extrusion process; and then the structure uniformity of the pipe is controlled by a cold rolling or cold drawing process and a matched heat treatment process, so that the pipe with excellent comprehensive performance is obtained, and the pipe is particularly suitable for the manufacturing requirements of a nuclear power steam generator.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
Specification of
Figure GDA0002491222390000061
The preparation of the large-caliber pipe.
1) Forging cast ingot into intermediate round pipe blank
Smelting an alloy ingot with the following chemical components (weight percentage):
c: 0.03%, P: 0.010%, S: 0.002%, Si: 0.2%, Mn: 0.20%, Cr: 20.0%, Ni: 61.9%, Cu: 0.020%, Mo: 8.5%, Nb: 3.3%, Al: 0.47%, Ti: 0.48%, Al + Ti: 0.95%, Fe: 5.0%, Co: 0.01%, Mg: 0.002%, and the balance unavoidable impurities.
Heating the cast ingot, forging to an intermediate octagonal specification by adopting a rapid forging press, then heating to a heating furnace, finally forging to a black skin forging rod by adopting a radial forging machine, and turning finish (namely an intermediate round pipe blank) after air cooling, wherein the blank surface finish Ra of the intermediate round pipe blank is less than or equal to 1.6 mu m.
2) Hot extruding the middle round pipe blank into a hollow billet
Performing tubular billet hot extrusion on the intermediate round tubular billet obtained in the step 1) by adopting a hot extrusion machine according to the hot extrusion process of the following steps, wherein the size of the tubular billet subjected to hot extrusion is
Figure GDA0002491222390000062
Then quickly removing the mixture of oxide skin and glass powder in the mixed solution of hydrofluoric acid and nitric acid, and folding and cracking the surface of the hollow billetAnd carrying out manual grinding on the pits. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 5% and the weight percentage concentration of nitric acid is 10%, and the mixed aqueous solution is soaked for 50 min.
The steps of hot extrusion into a tubular billet are as follows:
a) preheating the obtained intermediate round pipe blank to 1000 ℃ and preserving heat for 1.5 minutes for each millimeter of blank;
b) heating the preheated middle round pipe blank to 1180 ℃ and preserving heat for 3 minutes for each centimeter of blank;
c) uniformly coating glass lubricant on the inner surface and the outer surface of the heated intermediate circular tube blank, coating the glass lubricant on the inner wall of an extrusion cylinder of a die, putting the intermediate circular tube blank coated with the lubricant into the extrusion cylinder, and hot-extruding the intermediate circular tube blank into a tubular billet; the temperature of the middle round pipe blank in the hot extrusion process is 1180 ℃, the extrusion ratio is controlled to be 3 in the hot extrusion process, and the extrusion speed is 100 mm/s;
d) rapidly cooling the hot extruded capillary to room temperature by adopting water;
e) removing oxide skin of the tubular billet subjected to the solution treatment to obtain a tubular billet with a defect-free surface; when removing oxide skin, placing the capillary in a mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove the mixture of the oxide skin and glass powder, and manually grinding folds, cracks and pits on the surface of the capillary; in the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 5% and the weight percentage concentration of nitric acid is 10%, and the mixed aqueous solution is soaked for 50 min.
3) Processing of finished pipes
a) Performing 3-pass expanding drawing on the capillary tube with the flawless surface obtained in the step 2) to prepare the capillary tube
Figure GDA0002491222390000071
The expansion deformation of the hollow billet in each pass is 20 percent. Carrying out solution treatment on the pipe after each pass of expansion and drawing, adopting water cooling, then placing the pipe after solution treatment in mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove oxide skin, then carrying out high-pressure water washing, and folding and cracking the surface of the pipeAnd carrying out manual grinding on the pits. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 5%, the weight percentage concentration of nitric acid is 10%, and the soaking time is 40 min.
b) Good for solution treatment
Figure GDA0002491222390000072
And (3) rolling the pipe again to form a finished product specification:
Figure GDA0002491222390000073
then cold-rolled to finished products
Figure GDA0002491222390000074
The steel pipe is subjected to finished product solution treatment, the solution temperature is 1100 ℃, water cooling is adopted, then the pipe subjected to solution treatment is placed in a mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove oxide skin, then high-pressure water washing is carried out, and manual coping is carried out on folds, cracks and pits on the surface of the pipe. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 5%, the weight percentage concentration of nitric acid is 10%, and the soaking time is 40 min.
4) Inspection of finished product
The grain size of the finished pipe is 4.5 grade, and the room temperature tensile strength is as follows: 780MPa, room temperature yield strength: 370MPa, room temperature elongation: 65 percent; high temperature strength at 750 ℃: 530MPa, yield strength: 240MPa, elongation: 101 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is 81.3MPa, and the endurance performance is remarkable; the GB/T15260B method is adopted to avoid intergranular corrosion defects; flattening until the distance between the inner walls is 2 times of the wall thickness, and no crack exists after a flattening test; the qualification rate of the 20MPa hydrostatic test is 100 percent after the pipes are subjected to root by root; the pipe is subjected to liquid permeation inspection one by one, the qualified rate is 100%, and the manufacturing requirement of the high-temperature gas cooled reactor steam generator is met.
Example 2
Specification of
Figure GDA0002491222390000081
The preparation of the large-caliber pipe.
1) Forging cast ingot into intermediate round pipe blank
Smelting an alloy ingot with the following chemical components (weight percentage):
c: 0.04%, P: 0.005%, S: 0.010%, Si: 0.01%, Mn: 0.50%, Cr: 23.0%, Ni: 60.43%, Cu: 0.20%, Mo: 9.5%, Nb: 3.8%, Al: 0.50%, Ti: 0.50%, Al + Ti: 1.0%, Fe: 1.0%, Co: 0.01%, Mg: 0.005% and the balance inevitable impurities.
Heating the cast ingot, forging to an intermediate octagonal specification by adopting a rapid forging press after the cast ingot is subjected to 47% deformation, then heating to a heating furnace for heating, finally forging to a black skin forging rod by adopting a radial forging machine, and turning finish (namely an intermediate round pipe blank) after air cooling, wherein the blank surface finish Ra of the intermediate round pipe blank is less than or equal to 1.6 mu m.
2) Hot extruding the middle round pipe blank into a hollow billet
Carrying out capillary hot extrusion on the smooth blank obtained in the step 1) by adopting a hot extrusion machine according to the hot extrusion process of the following steps, wherein the size of the capillary hot extruded is
Figure GDA0002491222390000082
And then quickly removing the mixture of oxide skin and glass powder in a mixed solution of hydrofluoric acid and nitric acid, and manually polishing the folds, cracks and pits on the surface of the hollow billet. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 8% and the weight percentage concentration of nitric acid is 15%, and the mixed aqueous solution is soaked for 50 min.
The steps of hot extrusion into a tubular billet are as follows:
a) preheating the obtained intermediate round pipe blank to 1050 ℃ and preserving heat for 1.0 minute for each millimeter of blank;
b) heating the preheated intermediate round pipe blank to 1200 ℃ and preserving heat for 1 minute for each centimeter of blank;
c) uniformly coating glass lubricant on the inner surface and the outer surface of the heated intermediate circular tube blank, coating the glass lubricant on the inner wall of an extrusion cylinder of a die, putting the intermediate circular tube blank coated with the lubricant into the extrusion cylinder, and hot-extruding the intermediate circular tube blank into a tubular billet; the temperature of the middle round pipe blank in the hot extrusion process is 1200 ℃, the extrusion ratio is controlled to be 3 in the hot extrusion process, and the extrusion speed is 200 mm/s;
d) rapidly cooling the hot extruded capillary to room temperature by adopting water;
e) removing oxide skin of the tubular billet subjected to the solution treatment to obtain a tubular billet with a defect-free surface; when removing oxide skin, placing the capillary in a mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove the mixture of the oxide skin and glass powder, and manually grinding folds, cracks and pits on the surface of the capillary; in the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 8% and the weight percentage concentration of nitric acid is 15%, and the mixed aqueous solution is soaked for 50 min.
3) Processing of finished pipes
a) Carrying out 1-pass cold rolling on the surface-defect-free tubular billet obtained in the step 2), namely, carrying out cold rolling on the tubular billet
Figure GDA0002491222390000091
Pass deformation of 44%, then cold rolling to finished product
Figure GDA0002491222390000092
The steel pipe is subjected to finished product solution treatment, the solution temperature is 1200 ℃, water cooling is adopted, then the pipe subjected to solution treatment is placed in a mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove oxide skin, then high-pressure water washing is carried out, and manual coping is carried out on folds, cracks and pits on the surface of the pipe. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 8%, the weight percentage concentration of nitric acid is 15%, and the soaking time is 50 min.
4) Inspection of finished product
The grain size of the finished pipe is 3 grade, and the room temperature tensile strength is as follows: 750MPa, room temperature yield strength: 350MPa, room-temperature elongation: 69%; high temperature strength at 750 ℃: 510MPa, yield strength: 230MPa, elongation: 110 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is 79MPa, and the endurance performance is remarkable; the GB/T15260B method is adopted to avoid intergranular corrosion defects; the distance between the inner walls after flattening is 2 times of the wall thickness, and no crack is generated after the flattening test(ii) a The qualification rate of the 20MPa hydrostatic test is 100 percent after the pipes are subjected to root by root; the liquid permeation inspection is carried out on the pipes one by one, and the qualified rate is 100%. The manufacturing requirement of the high-temperature gas cooled reactor steam generator is met.
Example 3
Specification of
Figure GDA0002491222390000101
Preparing the small-caliber pipe.
1) Forging cast ingot into intermediate round pipe blank
Smelting an alloy ingot with the following chemical components (weight percentage):
c: 0.035%, P: 0.008%, S: 0.008%, Si: 0.3%, Mn: 0.30%, Cr: 21.5%, Ni: 61.33%, Cu: 0.10%, Mo: 9.0%, Nb: 3.5%, Al: 0.45%, Ti: 0.45%, Al + Ti: 0.9%, Fe: 3.0%, Co: 0.01%, Mg: 0.003% and the balance inevitable impurities.
Heating the cast ingot, forging to an intermediate octagonal specification by adopting a quick forging press after the cast ingot is subjected to 50% deformation, then heating to a heating furnace for heating, finally forging to a black skin forging rod by adopting a radial forging machine, and turning finish (namely an intermediate round pipe blank) after air cooling, wherein the blank surface finish Ra of the intermediate round pipe blank is less than or equal to 1.6 mu m.
2) Hot extruding the middle round pipe blank into a hollow billet
Carrying out capillary hot extrusion on the smooth blank obtained in the step 1) by adopting a hot extrusion machine according to the hot extrusion process of the following steps, wherein the size of the capillary hot extruded is
Figure GDA0002491222390000102
And then quickly removing the mixture of oxide skin and glass powder in a mixed solution of hydrofluoric acid and nitric acid, and manually polishing the folds, cracks and pits on the surface of the hollow billet. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 7% and the weight percentage concentration of nitric acid is 13%, and the mixed aqueous solution is soaked for 50 min.
The steps of hot extrusion into a tubular billet are as follows:
a) preheating the obtained intermediate round pipe blank to 1050 ℃ and preserving heat for 1.0 minute for each millimeter of blank;
b) heating the preheated intermediate circular tube blank to 1190 ℃ and preserving heat for 1 minute for each centimeter of blank;
c) uniformly coating glass lubricant on the inner surface and the outer surface of the heated intermediate circular tube blank, coating the glass lubricant on the inner wall of an extrusion cylinder of a die, putting the intermediate circular tube blank coated with the lubricant into the extrusion cylinder, and hot-extruding the intermediate circular tube blank into a tubular billet; the temperature of the middle round pipe blank in the hot extrusion process is in the range of 1190 ℃, the extrusion ratio is controlled to be 10.5 in the hot extrusion process, and the extrusion speed is 150 mm/s;
d) rapidly cooling the hot extruded capillary by adopting water;
e) removing oxide skin of the tubular billet subjected to the solution treatment to obtain a tubular billet with a defect-free surface; when removing oxide skin, placing the capillary in a mixed aqueous solution of hydrofluoric acid and nitric acid to quickly remove the mixture of the oxide skin and glass powder, and manually grinding folds, cracks and pits on the surface of the capillary; in the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 7% and the weight percentage concentration of nitric acid is 13%, and the mixed aqueous solution is soaked for 45 min.
3) Processing of finished pipes
a) Performing 3-pass cold rolling on the surface-defect-free tubular billet obtained in the step 2) until the tubular billet is subjected to the cold rolling
Figure GDA0002491222390000111
The cold rolling deformation of each pass is 30%, 40% and 60%. And (3) carrying out solid solution treatment on the pipe subjected to each cold rolling pass, wherein the solid solution temperature is 1120, water cooling is adopted, then the pipe subjected to the solid solution treatment is placed in a mixed aqueous solution of hydrofluoric acid and nitric acid to rapidly remove oxide skin, then high-pressure water washing is carried out, and the folds, cracks and pits on the surface of the pipe are manually polished. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 7%, the weight percentage concentration of nitric acid is 13%, and the soaking time is 45 min.
And the temperature of the finished product is 1180 ℃, water cooling is adopted, then the pipe subjected to the solution treatment is placed in a mixed aqueous solution of hydrofluoric acid and nitric acid to rapidly remove oxide skin, then high-pressure water washing is carried out, and folding, cracks and pits on the surface of the pipe are manually polished. In the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of hydrofluoric acid is 7%, the weight percentage concentration of nitric acid is 13%, and the soaking time is 450 min.
4) Inspection of finished product
The grain size of the finished pipe is 5 grade, and the room temperature tensile strength is as follows: 780MPa, room temperature yield strength: 380MPa, room-temperature elongation: 64 percent; high temperature strength at 750 ℃: 530MPa, yield strength: 250MPa, elongation: 100 percent; extrapolation of 10 at 750 ℃5The hour endurance strength is 82MPa, and the endurance performance is remarkable; the GB/T15260B method is adopted to avoid intergranular corrosion defects; flattening until the distance between the inner walls is 2 times of the wall thickness, and no crack exists after a flattening test; the qualification rate of the 20MPa hydrostatic test is 100 percent after the pipes are subjected to root by root; the liquid permeation inspection is carried out on the pipes one by one, and the qualified rate is 100%. The manufacturing requirement of the high-temperature gas cooled reactor steam generator is met.

Claims (10)

1. A nickel-based corrosion-resistant alloy pipe for a high-temperature gas cooled reactor steam generator comprises the following chemical components in percentage by weight: c: 0.03-0.04%, P is less than or equal to 0.010%, S is less than or equal to 0.010%, Cr: 20.0-23.0%, Ni is more than or equal to 58.0%, Mo: 8.5-9.5%, Nb: 3.3-3.8%, Al: 0.35-0.60%, Ti: 0.35-0.48%, Mg: 0.002-0.005%, Fe: 3.0-5.0%, and the balance of inevitable impurities, wherein the elements simultaneously satisfy:
Al+Ti:0.90~1.0%;
at least one of Si more than 0 and less than or equal to 0.3 percent, Mn more than 0 and less than or equal to 0.50 percent, Cu more than 0 and less than or equal to 0.20 percent and Co more than 0 and less than or equal to 0.08 percent;
the microstructure of the nickel-based corrosion-resistant alloy pipe is isometric crystal, and the grain size is 3-5 grade; the tensile strength at room temperature of the nickel-based corrosion-resistant alloy pipe is more than or equal to 700MPa, the yield strength is more than or equal to 300MPa, and the elongation is more than or equal to 40%; the high-temperature strength at 750 ℃ is more than or equal to 500MPa, the yield strength is more than or equal to 210MPa, and the elongation is more than or equal to 90 percent;
extrapolation of 10 at 750 ℃5The hour endurance strength is more than or equal to 75.3 MPa.
2. The method for manufacturing the nickel-based corrosion-resistant alloy tube material for the steam generator of the high temperature gas cooled reactor according to claim 1, comprising the steps of:
1) smelting and forging
Smelting and casting the mixture into an ingot according to the chemical composition proportion of claim 1, and forging the ingot into an intermediate round pipe blank, wherein the deformation in the forging process is 20-50%;
2) hot extruding the middle round pipe blank into a hollow billet
Preheating the intermediate round pipe blank obtained in the step 1) to 1000-1050 ℃ and preserving heat, and then heating to 1200-1230 ℃ and preserving heat; then, hot extruding to obtain a tubular billet, and cooling the tubular billet to room temperature by water, wherein the temperature of the middle round tube billet in the hot extrusion process is 1180-1200 ℃, the extrusion ratio is 2-20, and the extrusion speed is 100-200 mm/s; finally, removing oxide skin of the tubular billet to obtain the tubular billet with a defect-free surface;
3) cold working
Cold rolling or expanding and drawing the tubular billet obtained in the step 2), wherein the deformation of a cold rolling pass is 30-60% or the deformation of an expanding and drawing pass is 10-20%; if the cold rolling or drawing passes are more than two times, carrying out solid solution treatment and oxide skin removal between adjacent cold rolling or drawing passes, wherein the temperature of the solid solution treatment is 1100-1200 ℃; if the cold rolling or the expanding drawing pass is one time, directly carrying out subsequent processing;
4) performing solution treatment on the finished pipe, wherein the temperature of the solution treatment is 1100-1200 ℃;
5) and (5) surface treatment of the finished pipe.
3. The method for manufacturing the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator according to claim 2, wherein in the step 1), the forging process to form the intermediate circular pipe blank comprises the following steps: heating the smelted cast ingot, forging the cast ingot to an intermediate specification by using a quick forging press with the deformation of 20-50%, then reheating, finally forging the cast ingot to a black forged rod by using a radial forging machine, and turning and polishing the cast ingot to form the intermediate round pipe blank after air cooling.
4. The method for manufacturing the nickel-based corrosion-resistant alloy pipe for the high temperature gas cooled reactor steam generator according to claim 2, wherein the surface finish Ra of the intermediate round pipe blank obtained in the step 1) is less than or equal to 1.6 μm.
5. The method for manufacturing the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator according to claim 2, wherein in the step 2), the heat preservation time of the preheated intermediate circular pipe blank is 0.5-1.5 minutes per millimeter of blank heat preservation.
6. The method for manufacturing the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator according to claim 2, wherein in the step 2), the heat preservation time of the heated intermediate circular pipe blank is 1-3 minutes per centimeter of thickness of the blank.
7. The method according to claim 2, wherein in the step 2), the lubricant is uniformly coated on the inner and outer surfaces of the heated intermediate circular tube blank during hot extrusion, the lubricant is coated on the inner wall of the extrusion cylinder of the die, and the intermediate circular tube blank coated with the lubricant is placed into the extrusion cylinder for hot extrusion into the tubular billet.
8. The method according to claim 7, wherein the lubricant is a glass lubricant.
9. The manufacturing method of the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator according to claim 2, wherein in the step 2) and the step 4), when the oxide skin is removed, the pipe is soaked in a mixed aqueous solution of hydrofluoric acid and nitric acid for 40-50 min to remove the oxide skin, then high-pressure water washing is carried out, and folds, cracks and pits on the surface of the pipe are polished; in the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of the hydrofluoric acid is 5-8%, and the weight percentage concentration of the nitric acid is 10-15%.
10. The method for manufacturing the nickel-based corrosion-resistant alloy pipe for the high-temperature gas-cooled reactor steam generator according to claim 2, wherein in the step 5), the surface treatment of the finished pipe comprises the following steps: soaking the pipe in a mixed aqueous solution of hydrofluoric acid and nitric acid for 40-50 min to remove oxide skin, then washing the pipe with high-pressure water, and polishing folds, cracks and pits on the surface of the pipe; in the mixed aqueous solution of hydrofluoric acid and nitric acid, the weight percentage concentration of the hydrofluoric acid is 5-8%, and the weight percentage concentration of the nitric acid is 10-15%.
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