1. The iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler is characterized by comprising the following components in percentage by weight: c: 0.04-0.06%, less than or equal to 0.30% of Si, less than or equal to 0.10% of Mn, less than or equal to 0.020% of P, less than or equal to 0.008% of S, Cr: 21.00-22.00%, Ti: 1.00-1.30%, Al: 0.70-1.00%, Mo: 2.10-2.40%, Nb: 1.00-1.30%, Fe: 19.00-20.00 percent of N, less than or equal to 0.008 percent of B, less than or equal to 0.006 percent of B, and the balance of Ni and trace elements, wherein the sum of the components is 100 percent.

2. A method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 1, comprising the steps of: the method comprises the following steps of duplex process smelting (vacuum induction and vacuum consumable), forging, hot extrusion, solution heat treatment, intermediate cold rolling, solution heat treatment, final cold rolling, finished product heat treatment, straightening, acid washing, surface grinding, finished product inspection, cleaning, marking and packaging, and specifically comprises the following steps:

first, smelting

Smelting the alloy material by adopting a vacuum induction and vacuum self-consumption duplex process, firstly adding the ingredients into a vacuum induction furnace for vacuumizing, starting heating when the vacuum degree is less than 100Pa, adding a deoxidizing agent, casting the alloy ingot after smelting, and then performing vacuum self-consumption;

second, forging

Cogging the alloy ingot obtained in the step one by adopting a 2000-ton quick forging machine into an octagonal blank, and then forging by adopting a 1300-ton radial forging machine;

three, hot extrusion

Peeling the surface of the forging stock obtained in the step two, then sizing, machining into a hot extrusion stock, and then hot extruding into a hot extrusion pipe at 1100-1200 ℃;

solution heat treatment and acid pickling of tube blank

Carrying out solution heat treatment on the hot extrusion pipe obtained in the step three in a high-temperature box furnace, wherein the heat treatment temperature is 1100-1200 ℃, the heat preservation time is 30-60 min, the cooling mode is water cooling, then straightening is carried out, head and tail defects are cut off and burrs are removed, mixed liquor is adopted for carrying out acid pickling at 50-70 ℃, then washing is carried out to remove residual acid, and the inner surface and the outer surface are subjected to polishing treatment;

the mixed solution comprises the following components in percentage by mass: hydrofluoric acid: 5-8%, nitric acid: 10-15% of water, and the balance of water, wherein the sum of the components is 100%;

pipe end treatment

Inspecting, grinding and polishing the inner surface and the outer surface of the seamless pipe obtained in the fourth step, and chamfering the outer wall of one end of the seamless pipe by 30-60 degrees;

sixth, intermediate cold rolling and solution heat treatment

Performing multiple-pass cold rolling on the seamless pipe processed in the fifth step by using a cold rolling mill, removing oil after each pass of cold rolling, performing intermediate solution heat treatment in a continuous roller hearth furnace, and performing straightening, acid washing, inspection and grinding, internal and external surface polishing and chamfering treatment;

seventh, finished product cold rolling and finished product heat treatment

Performing cold rolling, deoiling and heat treatment on the finished product of the alloy pipe processed in the step six, and then performing straightening, acid pickling, inspection and grinding, polishing the inner surface and the outer surface, sizing and cleaning burrs on the inner surface and the outer surface of two ends;

eighthly, finished product inspection

And step seven, carrying out finished product inspection on the seamless pipes one by one, wherein the finished product inspection comprises ultrasonic inspection, eddy current inspection, physical and chemical inspection, surface quality inspection and size inspection, and the finished product inspection comprises the following steps:

the ultrasonic inspection is carried out according to the regulation of GB/T5777 plus 2008, and the size of the standard sample artificial defect is 0.20mm multiplied by 20mm multiplied by 0.40mm (depth multiplied by length multiplied by width);

the eddy current inspection is carried out according to the regulation of GB/T7735-2016, and the diameter of the standard sample through hole is phi 1.00 mm;

the physical and chemical inspection comprises chemical components, tensile test at 25-700 ℃, Hardness (HBW) and grain size; in addition, after sampling of a physical and chemical inspection sample, carrying out simulated aging heat treatment on the sample, and then carrying out room-temperature stretching and hardness detection;

the surface quality inspection comprises roughness, and the size inspection comprises outer diameter, wall thickness and straightness;

nine steps of cleaning

Cleaning the outer surface: wiping the outer surface of the alloy pipe with cotton cloth dipped with acetone or alcohol one by one until the outer surface is free from oil stains and color spots caused by foreign matters, and finally wiping the alloy pipe clean with dry white cotton cloth;

cleaning the inner surface: cleaning the wool felt plugs one by dipping with acetone or alcohol and blowing high-pressure nitrogen into the tube holes until the surfaces of the cleaned wool felt plugs are free of oil stains and color spots caused by foreign matters, and finally drying the wool felt plugs or white cotton cloth;

ten, sign and package

Marking the outer surface of the seamless pipe one by adopting a laser code spraying mode;

cleaning each seamless pipe after marking, immediately sealing two ends by using plastic plugs after cleaning, sleeving the seamless pipes one by adopting pentachloroethylene plastic bags, wrapping the outer surface of the seamless pipe by using a fabric after the seamless pipe is bundled, and tightly fastening and bundling each bundle of seamless pipes into a hexagon by using a thin steel belt.

3. The method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 2, characterized in that: in the sixth step, the seamless pipe subjected to chamfering treatment on the surface of the fifth step and the outer wall of one end of the seamless pipe is subjected to cold rolling through the precise matching of a cold rolling hole pattern and a core rod, the deformation of the cold rolling is controlled to be 25-55%, the feeding amount is 1-5 mm/time, the rolling speed is 20-60 times/min, and the mixed aqueous solution of 1% hydrofluoric acid and 10-15% nitric acid is adopted for deoiling after each cold rolling, and the temperature is 45-65 ℃; and performing intermediate solution heat treatment in a continuous roller hearth furnace, wherein the temperature of the intermediate solution heat treatment is 1150-1200 ℃, the heat preservation time is calculated according to the wall thickness of the seamless pipe, the cooling mode is water cooling, degreasing and solution heat treatment are performed after each pass of cold rolling, straightening, acid pickling, polishing the inner surface and the outer surface, and chamfering the outer wall at one end by 30-60 degrees.

4. The method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 2, characterized in that: and seventhly, performing heat treatment on the finished alloy finished pipe in a continuous roller hearth furnace at the temperature of 1125-1175 ℃, wherein the heat preservation time is calculated according to the wall thickness of the seamless pipe by 2-3 min/mm, and the cooling mode is water cooling.

5. The method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 2, characterized in that: and eighthly, performing simulated aging heat treatment in a high-temperature box type furnace, wherein the heat treatment temperature is 730-780 ℃, the heat preservation time is more than or equal to 4 hours, the cooling mode is air cooling, straightening is performed after the heat treatment, and the straightness is controlled to be less than or equal to 1.0mm/m after the straightening.

6. The method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 2, characterized in that: and step ten, when each bundle of finished pipes is bundled by a thin steel belt, the thin steel belt is kept flush with one end of each bundle of finished pipes, two thin steel belts are bound at the position, 20-30cm away from the head, of the two ends of each bundle of finished pipes, the thin steel belts at other positions of each bundle of finished pipes are uniformly bundled, and the weight of each bundle of seamless pipes is not more than 2000 Kg.

7. The method for manufacturing an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra supercritical boiler according to claim 2, characterized in that: the allowable deviation of the outer diameter of the alloy seamless pipe is +/-0.20 mm, the allowable deviation of the wall thickness is +/-8%, and the straightness is less than or equal to 1.0 mm/m; the roughness Ra of the inner surface and the outer surface is less than or equal to 1.6 mu m; the grain size is 3-7 grade;

mechanical properties in solid solution state: r at room temperature_m：600～800MPa，R_p0.2：205～430MPa，A≥40%，R_mDenotes tensile strength, R_p0.2The yield strength is shown, A represents elongation after fracture, and the hardness HBW is less than or equal to 190; high-temperature mechanical properties: at 100 ℃, R_m≥550MPa，R_p0.2More than or equal to 175MPa, and A more than or equal to 35 percent; at 200 ℃, R_m≥520MPa，R_p0.2Not less than 125MPa, A not less than 30%; at 300 ℃, R_m≥515MPa，R_p0.2Not less than 115MPa, A not less than 30%; at 400 ℃, R_m≥485MPa，R_p0.2Not less than 105MPa, A not less than 30%; at 500 ℃, R_m≥470MPa，R_p0.2More than or equal to 100MPa, A more than or equal to 35 percent; at 600 ℃, R_m≥430MPa，R_p0.2More than or equal to 100MPa, A more than or equal to 35 percent; at 700 ℃ R_m≥410MPa，R_p0.2≥100Mpa，A≥35%；

Mechanical properties in an aging state: the simulated aging heat treatment temperature is 730-780 ℃, the heat preservation time is more than or equal to 4h, and air cooling is carried out;

r at room temperature_m≥900MPa，R_p0.2≥430MPa，A≥18%，R_mDenotes tensile strength, R_p0.2The yield strength is shown, A represents elongation after fracture, and the hardness HBW is less than or equal to 290.

Background

For a long time, thermal power is a main component of electric power energy in China, and in recent years, the thermal power accounts for more than 70% of the electric power industry in China although the proportion of new energy such as nuclear power is increased. With the improvement of global requirements on environmental protection, energy conservation and emission reduction become more important, thermal power technology research with higher steam temperature and pressure is carried out in all countries, and the 700 ℃ advanced ultra-supercritical thermal power technology is the most important research and development direction. Researches show that the power generation efficiency can be greatly improved by improving the steam temperature and the steam pressure of the thermal power generating unit, so that the coal consumption is reduced, the emission is reduced, and the cost is reduced. When the steam temperature is increased to 700 ℃ and the pressure reaches 35 MPa, the thermal power generation efficiency can reach more than 50 percent, compared with the existing 600 ℃ ultra-supercritical thermal power generating unit, the thermal power generation efficiency can be increased by more than 5 percent, and the coal consumption can be reduced by about 23 g/kWh. If the advanced ultra-supercritical thermal power technology is adopted in new and existing thermal power generating units in China, more than 1 million tons of coal can be saved every year, and the exploitation of primary energy coal is greatly reduced, so that the exploitation electric power is saved, and in addition, the damage and the pressure to road and railway transportation can be reduced. Therefore, the development of the 700 ℃ advanced ultra-supercritical fossil power technology has important strategic significance for optimizing the energy structure of China, improving the utilization efficiency of coal resources, obviously reducing the consumption of fire coal, effectively controlling the emission of greenhouse gases and harmful gases and realizing the energy conservation and emission reduction of China and the sustainable development of the energy industry.

At present, 700 ℃ advanced ultra-supercritical fossil power technology is in a research and development stage in all countries in the world, and China develops relatively late. The national energy agency organizes and establishes a national 700 ℃ ultra supercritical coal-fired power generation technology innovation alliance (hereinafter referred to as an alliance) in 2010, sets up key projects in the field of national energy, and develops a series of researches on aspects of overall scheme design, high-temperature material technology, boiler design and manufacture technology, establishment and operation of a key component test platform, engineering feasibility research of a demonstration power station and the like. Along with the continuous improvement of the parameters of the thermal power generating unit, the performance level of the high-temperature material plays a key role. When the steam temperature is increased to 700 ℃ and the pressure reaches 35 MPa, the prior ferrite and austenitic stainless steel materials suitable for a unit at 600 ℃ can not meet the requirements of unit parameters. The basic requirements of the 700 ℃ advanced ultra supercritical unit on high-temperature materials are as follows: high-temperature creep resistance, high-temperature corrosion resistance, long-term structure stability, steam oxidation resistance of the inner wall of the pipe, smoke corrosion resistance and fly ash erosion resistance of the outer wall of the pipe, good cold and hot processing technology, good welding performance, low cost and the like. In order to meet the requirements, high-temperature parts such as a superheater, a reheater, a high-temperature steam pipeline, a header, a valve, a steam turbine rotor, a blade and the like of the overhigh-temperature section are made of nickel-based alloy materials. Because the nickel-based alloy material is expensive, the research and development of iron-nickel-based alloy materials such as GH2984 and HT700 are actively carried out in China besides corresponding research on alloys such as Inconel617, Nimonic 263, Inconel740/740H, Haynes 230 and Haynes 282 for 700 ℃ advanced ultra-supercritical boiler.

The iron-nickel-based high-temperature alloy has high alloying degree and large deformation resistance, and is difficult to smelt and manufacture. At present, few reports are made on the industrial production of the iron-nickel-based high-temperature alloy for the 700 ℃ advanced ultra-supercritical boiler in foreign countries, the iron-nickel-based high-temperature alloy is always in a blocked state in foreign countries, and no relevant report is made on the industrial production in domestic countries. Therefore, a preparation process of the iron-nickel alloy seamless tube which has good high-temperature structure, mechanical stability, corrosion resistance, high dimensional precision and surface quality and is suitable for 700 ℃ advanced ultra-supercritical boilers is urgently needed.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler and the manufacturing method thereof, wherein the iron-nickel alloy seamless tube has good structure and mechanical property, good dimensional accuracy and surface quality, and the manufacturing method thereof solves the manufacturing process problem of the iron-nickel alloy seamless tube so as to meet the use requirement of the 700 ℃ advanced ultra-supercritical boiler.

In order to solve the technical problems, the invention provides an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra-supercritical boiler, which comprises the following components in percentage by weight: c: 0.04-0.06%, less than or equal to 0.30% of Si, less than or equal to 0.10% of Mn, less than or equal to 0.020% of P, less than or equal to 0.008% of S, Cr: 21.00-22.00%, Ti: 1.00-1.30%, Al: 0.70-1.00%, Mo: 2.10-2.40%, Nb: 1.00-1.30%, Fe: 19.00-20.00 percent of N, less than or equal to 0.008 percent of B, less than or equal to 0.006 percent of B, and the balance of Ni and trace elements, wherein the sum of the components is 100 percent.

The invention also designs a manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler, which comprises the following steps: the method comprises the following steps of duplex process smelting (vacuum induction and vacuum consumable), forging, hot extrusion, solution heat treatment, intermediate cold rolling, solution heat treatment, final cold rolling, finished product heat treatment, straightening, acid washing, surface grinding, finished product inspection, cleaning, marking and packaging, and specifically comprises the following steps:

first, smelting

Smelting the alloy material by adopting a vacuum induction and vacuum self-consumption duplex process, firstly adding the ingredients into a vacuum induction furnace for vacuumizing, starting heating when the vacuum degree is less than 100Pa, adding a deoxidizing agent, casting the alloy ingot after smelting, and then performing vacuum self-consumption;

second, forging

Cogging the alloy ingot obtained in the step one by adopting a 2000-ton quick forging machine into an octagonal blank, and then forging by adopting a 1300-ton radial forging machine;

three, hot extrusion

Peeling the surface of the forging stock obtained in the step two, then sizing, machining into a hot extrusion stock, and then hot extruding into a hot extrusion pipe at 1100-1200 ℃;

solution heat treatment and acid pickling of tube blank

Carrying out solution heat treatment on the hot extrusion pipe obtained in the step three in a high-temperature box furnace, wherein the heat treatment temperature is 1100-1200 ℃, the heat preservation time is 30-60 min, the cooling mode is water cooling, then straightening is carried out, head and tail defects are cut off and burrs are removed, mixed liquor is adopted for carrying out acid pickling at 50-70 ℃, then washing is carried out to remove residual acid, and the inner surface and the outer surface are subjected to polishing treatment;

the mixed solution comprises the following components in percentage by mass: hydrofluoric acid: 5-8%, nitric acid: 10-15% of water, and the balance of water, wherein the sum of the components is 100%;

pipe end treatment

Inspecting, grinding and polishing the inner surface and the outer surface of the seamless pipe obtained in the fourth step, and chamfering the outer wall of one end of the seamless pipe by 30-60 degrees;

sixth, intermediate cold rolling and solution heat treatment

Performing multiple-pass cold rolling on the seamless pipe processed in the fifth step by using a cold rolling mill, removing oil after each pass of cold rolling, performing intermediate solution heat treatment in a continuous roller hearth furnace, and performing straightening, acid pickling, inspection and grinding, internal and external surface polishing and chamfering treatment;

seventh, finished product cold rolling and finished product heat treatment

Carrying out cold rolling, deoiling and heat treatment on the finished alloy pipe after the sixth treatment, and then straightening, pickling, inspecting and grinding, polishing the inner surface and the outer surface, sizing and cleaning burrs on the inner surface and the outer surface of two ends;

eighthly, finished product inspection

And step seven, carrying out finished product inspection on the seamless pipes one by one, wherein the finished product inspection comprises ultrasonic inspection, eddy current inspection, physical and chemical inspection, surface quality inspection and size inspection, and the finished product inspection comprises the following steps:

the ultrasonic inspection is carried out according to the regulation of GB/T5777 plus 2008, and the size of the standard sample artificial defect is 0.20mm multiplied by 20mm multiplied by 0.40mm (depth multiplied by length multiplied by width);

the eddy current inspection is carried out according to the regulation of GB/T7735-2016, and the diameter of the standard sample through hole is phi 1.00 mm;

the physical and chemical inspection comprises chemical components, tensile test at 25-700 ℃, Hardness (HBW) and grain size; in addition, after sampling of a physical and chemical inspection sample, carrying out simulated aging heat treatment on the sample, and then carrying out room-temperature stretching and hardness detection;

the surface quality inspection comprises roughness, and the size inspection comprises outer diameter, wall thickness and straightness;

nine steps of cleaning

Cleaning the outer surface: wiping the outer surface of the alloy pipe with cotton cloth dipped with acetone or alcohol one by one until the outer surface is free from oil stains and color spots caused by foreign matters, and finally wiping the alloy pipe clean with dry white cotton cloth;

cleaning the inner surface: cleaning the wool felt plugs one by dipping with acetone or alcohol and blowing high-pressure nitrogen into the tube holes until the surfaces of the cleaned wool felt plugs are free of oil stains and color spots caused by foreign matters, and finally drying the wool felt plugs or white cotton cloth;

ten, sign and package

Marking the outer surface of the seamless pipe one by adopting a laser code spraying mode;

cleaning each seamless pipe after marking, immediately sealing two ends by using plastic plugs after cleaning, sleeving the seamless pipes one by adopting pentachloroethylene plastic bags, wrapping the outer surface of the seamless pipe by using a fabric after the seamless pipe is bundled, and tightly fastening and bundling each bundle of seamless pipes into a hexagon by using a thin steel belt.

The invention further defines the technical scheme as follows:

further, in the manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra supercritical boiler, in the sixth step, the seamless tube subjected to chamfering treatment on the surface of the fifth step and the outer wall of one end of the seamless tube is subjected to cold rolling through the precise matching of a cold rolling pass and a mandrel, the deformation of the cold rolling is controlled to be 25-55%, the feeding amount is 1-5 mm/time, the rolling speed is 20-60 times/min, and after each cold rolling pass, mixed aqueous solution of 1% hydrofluoric acid and 10-15% nitric acid is adopted for degreasing, and the temperature is 45-65 ℃; and performing intermediate solution heat treatment in a continuous roller hearth furnace, wherein the temperature of the intermediate solution heat treatment is 1150-1200 ℃, the heat preservation time is calculated according to the wall thickness of the seamless pipe, the cooling mode is water cooling, degreasing and solution heat treatment are performed after each pass of cold rolling, straightening, acid pickling, polishing the inner surface and the outer surface, and chamfering the outer wall at one end by 30-60 degrees.

In the seventh step of the manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler, the heat treatment of the finished alloy tube is carried out in a continuous roller hearth furnace, the temperature is 1125-1175 ℃, the heat preservation time is calculated according to the wall thickness of the seamless tube being 2-3 min/mm, and the cooling mode is water cooling.

In the manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler, the simulated aging heat treatment in the step eight is carried out in a high-temperature box type furnace, the heat treatment temperature is 730-780 ℃, the heat preservation time is more than or equal to 4 hours, the cooling mode is air cooling, straightening is carried out after the heat treatment, and the straightness is controlled to be less than or equal to 1.0mm/m after the straightening.

In the manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler, in the tenth step, when each bundle of finished tubes is bundled by a thin steel strip, the thin steel strip is kept flush with one end of each bundle of finished tubes, two thin steel strips are bound at the position, 20-30cm away from the head, of two ends of each bundle of finished tubes, the thin steel strips at other positions of each bundle of finished tubes are uniformly bundled, and the weight of each bundle of seamless tubes is not more than 2000 Kg.

In the manufacturing method of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler, the allowable deviation of the outer diameter of the alloy seamless tube is +/-0.20 mm, the allowable deviation of the wall thickness is +/-8%, and the straightness is less than or equal to 1.0 mm/m; the roughness Ra of the inner surface and the outer surface is less than or equal to 1.6 mu m; the grain size is 3-7 grade;

mechanical properties in solid solution state: r at room temperature_m：600～800MPa，R_p0.2：205～430MPa，A≥40%，R_mDenotes tensile strength, R_p0.2The yield strength is shown, A represents elongation after fracture, and the hardness HBW is less than or equal to 190; high-temperature mechanical properties: at 100 ℃, R_m≥550MPa，R_p0.2More than or equal to 175MPa, and A more than or equal to 35 percent; at 200 ℃, R_m≥520MPa，R_p0.2Not less than 125MPa, A not less than 30%; at 300 ℃, R_m≥515MPa，R_p0.2Not less than 115MPa, A not less than 30%; at 400 ℃, R_m≥485MPa，R_p0.2Not less than 105MPa, A not less than 30%; at 500 ℃, R_m≥470MPa，R_p0.2More than or equal to 100MPa, A more than or equal to 35 percent; at 600 ℃, R_m≥430MPa，R_p0.2More than or equal to 100MPa, A more than or equal to 35 percent; at 700 ℃ R_m≥410MPa，R_p0.2≥100Mpa，A≥35%；

Mechanical properties in an aging state: the simulated aging heat treatment temperature is 730-780 ℃, the heat preservation time is more than or equal to 4h, and air cooling is carried out; r at room temperature_m≥900MPa，R_p0.2≥430MPa，A≥18%，R_mDenotes tensile strength, R_p0.2The yield strength is shown, A represents elongation after fracture, and the hardness HBW is less than or equal to 290.

The invention has the beneficial effects that:

(1) the invention relates to a 700 ℃ advanced ultra supercritical boiler iron-nickel alloy seamless tube, which is prepared by selectively adding alloy elements such as 1.00-1.30% of Nb, 1.00-1.30% of Ti, 0.70-1.00% of Al and B less than or equal to 0.006%, wherein:

al and Ti: a small amount of gamma prime phase (Ni 3 (Al, Ti)) was formed, and precipitation strengthening was achieved.

Al and Cr: the combined action ensures that the coating has stronger high-temperature oxidation resistance.

Ni and Cr: the mass fraction is large, so that the alloy has strong corrosion resistance.

Cr, Mo, and Nb: has the solid solution strengthening effect and makes the alloy easy to form and weld.

Nb, Ti: the strong carbide forms elements, NbC and TiC are easy to form, the intergranular corrosion resistance is improved, and in addition, the carbide can play a pinning role and prevent grains from growing up, so that the grains are refined, and the strength is improved.

B: microalloying, improving creep strength and plasticity of the alloy.

The invention is an iron-nickel alloy, which has lower cost than nickel-based alloy, can resist high temperature, has good structure stability and high temperature strength at 700 ℃, has good plasticity, is easy to machine and form, and has lower manufacturing cost.

(2) The deformation of different materials is different, the deformation process and the heat treatment process are changed by utilizing the characteristics of the materials, the forming process adopts multi-pass cold rolling deformation, the deformation of each pass is controlled to be 25-55%, if the deformation of each pass exceeds 55%, the alloy pipe has the risk of cracking in the rolling process, if the deformation of each pass is lower than 25%, the deformation is smaller than the critical deformation, mixed crystals can be generated after the solution heat treatment, the uniformity of the matrix structure of the seamless pipe is influenced, and the performance uniformity of the seamless pipe is influenced, particularly the high-temperature long-term performance; the feeding amount of the 1 st pass is controlled to be 3-5 mm/time, the rolling speed is 30-60 times/min, the non-uniform deformation of the seamless pipe can be effectively prevented, and the obtained seamless pipe has good surface quality and small size deviation; the feeding amount of the subsequent pass is controlled to be 1-3 mm/time, the rolling speed is controlled to be 20-50 times/min, and the surface quality and the dimensional accuracy of the seamless pipe are further improved.

(3) The invention relates to a manufacturing step (VI) of an iron-nickel alloy seamless tube for a 700 ℃ advanced ultra-supercritical boiler, wherein before cold rolling, the outer wall of one end of each pass of the seamless tube needs to be subjected to chamfering treatment of 30-60 degrees, so that the stress concentration of the seamless tube is reduced when the cold rolling is started, and the head part is prevented from cracking during the rolling.

(4) The iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler has the advantages that the solution heat treatment temperature of a hot extrusion tube is 1100-1200 ℃, and the heat preservation time is 30-60 min, so that the seamless tube has good plasticity and can be smoothly cogging. The temperature of the solution heat treatment after the intermediate cold rolling is 1150-1200 ℃, and the heat preservation time is calculated according to the wall thickness of the alloy pipe about 2-3 min/mm, so that the seamless pipe is ensured to have good plasticity, and favorable conditions are provided for the cold rolling forming of the subsequent process. The heat treatment temperature of the finished product pipe is 1125-1175 ℃, and the cooling mode is water cooling; and eighthly, simulating aging heat treatment at 730-800 ℃, keeping the temperature for more than or equal to 4 hours, and cooling in an air cooling mode.

The manufacturing method of the invention adopts vacuum induction and vacuum consumable smelting, accurately controls alloy components, effectively controls non-metallic inclusions, improves the purity of the alloy, and adopts hot extrusion and cold rolling process for forming, so that the seamless tube has good tissue compactness, high temperature strength and corrosion resistance, and the comprehensive performance completely meets the use requirements of the iron-nickel alloy seamless tube for the 700 ℃ advanced ultra-supercritical boiler.