A GH3625 high temperature alloy pipe and its production process

Abstract

The present invention belongs to the technical field of high-temperature alloy material processing, and specifically discloses a GH3625 high-temperature alloy pipe and its production process, which includes: ingot smelting, ingot forging, bar solution treatment, first billet processing, billet non-destructive testing, primary hole expansion, secondary billet processing, secondary hole expansion, rough pipe extrusion, rough pipe solution treatment, cold rolling, finished pipe solution treatment, etc., and the GH3625 high-temperature alloy pipe is prepared by using this production process. The secondary hole expansion process solves the problem of cracking caused by a large hole expansion ratio in the first time. The use of double cone dies, carbon steel tail pads and other processes in rough pipe extrusion is conducive to the smooth flow of metal, reduces extrusion pressure, reduces extrusion defects, and improves the yield rate. The GH3625 high-temperature alloy pipe produced by the present invention has good surface quality, uniform grains, high dimensional accuracy, good mechanical and corrosion resistance, and is suitable for the production and preparation of GH3625 high-temperature alloy seamless pipes, especially the production and preparation of large-diameter pipes.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature alloy material processing, and in particular to a GH3625 high-temperature alloy pipe and a production process thereof. Background Art

[0002] GH3625 is a solid solution strengthened nickel-based deformable high temperature alloy with molybdenum and niobium as the main strengthening elements. It is also called UNSN06625 and Incone l625. This alloy has high strength, high toughness, excellent fatigue resistance and resistance to chloride ion stress corrosion from low temperature to 980℃. It is widely used in nuclear industry, aviation, aerospace, petrochemical and other fields.

[0003] One of the common products of GH3625 alloy is seamless pipe. Due to the characteristics of GH3625 alloy, GH3625 alloy pipe has large deformation resistance and narrow deformation temperature range during hot processing. It is easy to produce cracks when using conventional hot perforation process, and the forging process is slow and the precision is poor. At present, the hot extrusion process puts the billet in a three-dimensional compressive stress state, which is more conducive to improving the plastic deformation ability of the material and is suitable for hot processing of low-plasticity alloys. Therefore, the commonly used mainstream production process for GH3625 alloy pipe is: one-time hole expansion + extrusion of rough pipe + cold rolling. However, the existing process has the following problems: when producing larger diameter pipes, due to the large amount of hole expansion deformation, the problem of pipe expansion and cracking often occurs during the extrusion process; in order to reduce the amount of hole expansion deformation, the means of drilling a large inner hole diameter during billet processing will be adopted, which will lead to material waste. Summary of the invention

[0004] In order to solve the above deficiencies in the prior art, the present invention aims to provide a GH3625 high-temperature alloy pipe and a production process thereof, so as to solve the problem of cracking caused by a large hole expansion ratio in the prior art, avoid material waste caused by drilling a large inner hole diameter in the billet in the traditional process, and reduce extrusion defects, improve the quality and yield of the finished product by optimizing the alloy composition, double-cone die extrusion, adding a carbon steel tail pad and other means, and at the same time provide a GH3625 high-temperature alloy pipe prepared by this process.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The invention provides a GH3625 high-temperature alloy pipe, which comprises the following components by mass percentage: Mo: 8-10%, Nb: 3.25-4.00%, C: 0.003-0.065%, Cr: 20-23%, Fe≤5%, Cu≤0.30%, Al: 0.10-0.25%, Ti: 0.15-0.35%, Co≤1.0%, Si≤0.45%, Mn≤0.45%, S≤0.010%, P≤0.015%, B≤0.006%, Mg≤0.10%, W≤0.10%, and the rest are Ni and unavoidable impurities.

[0007] As a limitation of the present invention, the GH3625 high temperature alloy pipe is a seamless pipe with an outer diameter ranging from 19 mm to 325 mm and a wall thickness ranging from 1.5 mm to 40 mm;

[0008] The seamless pipe has the following properties: tensile strength Rm≥690MPa, Rp0.2 yield strength≥276MPa, elongation≥30%, grain size≥3.0 grade, and corrosion rate according to standard ASTM G28 A method<0.9mm / year.

[0009] The present invention also provides a production process for GH3625 high temperature alloy pipe, comprising the following steps performed in sequence:

[0010] S1. Ingot smelting: the alloy material is smelted into ingots through vacuum induction melting, vacuum casting electrode, and vacuum electroslag remelting technology;

[0011] S2. Ingot forging: heating the ingot to 1170°C to 1190°C for forging, with a final forging temperature of 950°C, forging it into a cylindrical bar with a forging ratio of 4 to 10;

[0012] S3, solution treatment of the bar, heating the cylindrical bar back to the furnace to 1130℃~1150℃, using water as the cooling medium to achieve rapid cooling; the furnace temperature when the bar enters the furnace is 900℃, the holding time is 2.0min~5.0min / mm, and the temperature is raised to the target temperature at a rate of 150℃~250℃ / h;

[0013] S4, the first blank processing, the bar is drilled with an inner hole, the outer circle is turned, and the two ends are flattened to obtain a blank; a bell mouth with an opening angle of α is processed at the inner circle of the blank head;

[0014] S5, non-destructive testing of the blank, performing ultrasonic testing on the blank obtained in S4;

[0015] S6, primary hole expansion, using a vertical hole expander to expand the heated billet once;

[0016] S7, process the blank again, turn the outer circle of the blank after the hole expansion, polish it, flatten the two ends, process the bell mouth with an angle of α' at the inner circle of the head of the blank, process the bevel angle with an angle of β at the outer circle of the tail, and process the fillet at the connection between the bevel and the ingot body;

[0017] S8, secondary hole expansion, the billet heated to temperature is expanded by a vertical hole expander;

[0018] S9, rough pipe extrusion, heating the billet after the secondary hole expansion in step S8 and then using a horizontal extruder to extrude the rough pipe;

[0019] S10, solution treatment of the rough pipe, heating to temperature in stages in a chamber furnace and then water cooling;

[0020] S11, cold rolling, using a pilger cold rolling mill for two to seven passes of cold rolling treatment, each pass deformation of 30% to 60%, feed amount 2.6 to 5.6 mm / time, rolling speed 30 to 60 times / minute, and the last pass of cold rolling deformation is controlled at 30% to 50%; the intermediate tube after each cold rolling is firstly removed from the cold rolling oil in the degreasing tank, and then the intermediate tube is solution treated, and then transferred to the mixed acid pickling tank for pickling to remove the oxide scale; the solution treatment process of the intermediate tube in the cold rolling stage is 1150 ° C heating time 3.0min to 6.0min / mm, and water is used as the cooling medium to achieve rapid cooling;

[0021] S12, solution treatment of finished tubes, cold-rolled tubes with an inner diameter of 35mm or more are heated to temperature and then water-cooled, the process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, water is used as cooling medium to achieve rapid cooling within 60S; cold-rolled tubes with an inner diameter less than 35mm and a wall thickness of less than 5mm are heat-treated in a protective atmosphere bright furnace annealing furnace, the process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, protective gas strong convection jet + water cooling jacket cooling;

[0022] S13, finishing, straightening, testing, surface treatment, flat head, packaging.

[0023] As a further limitation of the present invention: in S4, the bell mouth opening angle α processed at the inner circle of the head is 46°, the inner hole drilling deviation is ±0.5mm, and the outer diameter deviation of the finished outer circle is ±1mm; the end face verticality at both ends is ≤1mm; the inner and outer surfaces are ground and polished to remove scratches and tool mark defects, the surface roughness Ra≤1.6μm, the blank length deviation is ±5mm, and the concentricity of the inner and outer circles is ≤1mm.

[0024] As a further limitation of the present invention: the one-time hole enlarging step in S6 comprises:

[0025] ①When the temperature of the electric furnace is 950℃, put the billet into the furnace and keep it warm for 3.0h~6.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the temperature is evenly heated for 1.5~3.5min; the second heating power is 600kW~800kW, the frequency is 62~90Hz, the temperature reaches 1155℃~1180℃, and then it is taken out of the furnace;

[0026] ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200℃;

[0027] ③ After the blank is heated, the inner and outer surfaces are evenly coated with glass powder lubricant, and then the blank is placed in the reaming tube, and the reaming head is placed in the bell mouth of the blank head, and then the hole is expanded; the expansion speed is 130mm / s~180mm / s, the expansion ratio ranges from 1.02 to 1.28, and after expansion, it is cooled in water above 900℃.

[0028] As a further limitation of the present invention: in S7, the opening angle α' of the bell mouth processed at the inner circle of the head is 46°, the processing angle β at the outer circle of the tail is 35°, and the radius R of the fillet processed at the connection between the bevel and the ingot body is 20mm; the outer diameter deviation of the finished product is ±1mm; the verticality of the end faces at both ends is ≤1mm; the length deviation is ±5mm, and the concentricity of the inner and outer circles is ≤1mm; check whether the inner hole has defects and clean the defects; clean the cracks, folds, scars, and deep pit defects on the inner and outer surfaces, the grinding depth-width-length ratio is greater than 1:5:10, and the edges and corners are smoothly transitioned, and the surface roughness of all surfaces after cleaning is Ra≤1.6μm.

[0029] As a further limitation of the present invention: the secondary hole expansion step in S8 includes:

[0030] ① When the temperature of the electric furnace is 950℃, put it into the furnace and keep it warm for 2.0h~4.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the temperature is evenly heated for 1.0~2.5min; the second heating power is 600kW~800kW, the frequency is 65~100Hz, the temperature reaches 1160℃~1185℃, and then take it out of the furnace;

[0031] ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200°C;

[0032] ③ After the blank is heated, glass powder lubricant is evenly applied to the inner and outer surfaces, and then placed in the reaming tube, and then the reaming head is placed in the bell mouth above the blank, followed by reaming. The reaming speed is 150mm / s~200mm / s, and the reaming ratio ranges from 1.05 to 1.35.

[0033] As a further limitation of the present invention, the step of extruding the rough pipe in S9 includes:

[0034] ① After the second hole expansion is completed, the blank is turned around and then transferred to the secondary electromagnetic induction heating furnace with a heating power of 500kW to 800kW and a frequency of 40 to 70Hz. It is heated to 1160℃ to 1200℃ and then taken out of the furnace;

[0035] ② The inner wall of the extrusion barrel is heated to 300℃~500℃, and the surface of the extrusion die and core rod is heated to 250℃~450℃;

[0036] ③ Apply glass powder on the inner and outer surfaces of the blank, and then transfer it to the extrusion cylinder. The inner diameter of the extrusion cylinder is 4.5mm to 10mm larger than the outer diameter of the blank, and a glass pad is placed at the entrance of the extrusion die;

[0037] ④ Heat the prepared tail pad to a temperature of 950℃~1060℃, place it at the tail of the billet, and extrude the tail pad together with the billet;

[0038] ⑤ The power system of the extruder makes the extrusion rod push the billet to move in the extrusion direction. The billet advances at a speed of 60mm / s to 130mm / s. The extrusion ratio of the rough tube is 2.5 to 12.5. The billet metal passes through the cavity composed of the core rod and the extrusion die to become a rough tube. The extruded rough tube is cooled in water at a temperature above 960°C to below 40°C.

[0039] As a further limitation of the present invention: the extrusion die adopts a double cone die, the internal inlet of the double cone die is composed of two die angles, the die angle γ is 120°, and the die angle γ' is 30°; the length of the sizing zone of the extrusion die is 12mm; the fillet radius of the transition area between the die angle γ section and the die angle γ' section is 15mm, and the fillet radius of the transition area between the die angle γ' and the sizing zone is 12mm;

[0040] The tail pad is made of carbon steel, the outer diameter of the tail pad is the same as the outer diameter of the blank, the inner diameter of the tail pad is 4mm to 5mm larger than the inner diameter of the blank, and the length of the tail pad is 100mm.

[0041] As a further limitation of the present invention: the process of solid solution treatment of the rough pipe in S10 is: heating at 980℃ for 1.5min~2.0min / mm, heating to 1140℃ at a rate of 100℃~150℃ / h for 2.5min~5.0min / mm, and transferring to a water pool within 65S to use water as a cooling medium for rapid cooling.

[0042] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0043] (1) The hole expansion process of the present invention adopts secondary hole expansion, which solves the quality problem of cracking caused by using a large hole expansion ratio in the traditional process, and avoids the material waste caused by drilling a larger diameter inner hole in the blank;

[0044] (2) The present invention adopts a double-cone die in the extrusion die of the rough pipe extrusion stage, which is conducive to the smooth flow of metal, reduces the extrusion force, reduces extrusion defects, improves the quality of the rough pipe, and to a certain extent avoids the occurrence of unstable metal deformation, cracks in the wall thickness direction, delamination defects, etc. caused by the use of conventional flat die extrusion;

[0045] (3) The present invention adds a carbon steel tail pad behind the billet in the rough pipe extrusion stage. After the rough pipe extrusion is completed, the billet with a tail of about 25 mm to 50 mm can be extruded smoothly without causing material waste, thereby improving the yield rate.

[0046] In summary, the present invention is suitable for producing GH3625 alloy pipes with larger diameters. The diameter range of the finished pipes can be 19mm to 325mm, the wall thickness is 1.5mm to 40mm, and the tensile strength, yield strength, elongation, grain size, corrosion rate and other indicators of the finished products are higher than the requirements for product technical indicators in the relevant standards. The GH3625 high-temperature alloy pipes produced by the present invention have high dimensional accuracy, improved material utilization, good surface quality, uniform internal grains, and good mechanical and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a production process flow chart of an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the structure of the first blank processing in Example S4 of the present invention;

[0049] Figure 3 This is a schematic diagram of the structure of the second blank processing in Example S7 of the present invention;

[0050] Figure 4 Schematic diagram of the double cone mold structure in Example S9 of the present invention.

[0051] In the figure: 1-first processing of the blank, 2-second processing of the blank, 3-double cone die, 4-sizing belt. DETAILED DESCRIPTION

[0052] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and do not constitute a limitation of the present invention.

[0053] The present embodiment discloses a GH3625 high-temperature alloy pipe, which is a seamless pipe with an outer diameter ranging from 19 mm to 325 mm and a wall thickness ranging from 1.5 mm to 40 mm, and its composition by mass percentage is: Mo: 8-10%, Nb: 3.25-4.00%, C: 0.003-0.065%, Cr: 20-23%, Fe≤5%, Cu≤0.30%, Al: 0.10-0.25%, Ti: 0.15-0.35%, Co≤1.0%, Si≤0.45%, Mn≤0.45%, S≤0.010%, P≤0.015%, B≤0.006%, Mg≤0.10%, W≤0.10%, and the rest is Ni and unavoidable impurities.

[0054] The properties of GH3625 high temperature alloy pipe are: tensile strength Rm ≥ 690MPa, Rp0.2 yield strength ≥ 276MPa, elongation ≥ 30%, grain size ≥ 3.0 grade, and corrosion rate according to standard ASTM G28 A method < 0.9mm / year.

[0055] This embodiment also discloses a production process of GH3625 high temperature alloy pipe, taking the preparation of GH3625 high temperature alloy pipe finished seamless pipe of 219mm (diameter)×12.7mm (wall thickness) as an example. Figure 1 As shown, the production process and specific production and processing technology include the following steps:

[0056] S1. Ingot smelting: the alloy material is smelted into ingots through vacuum induction melting, vacuum casting electrode and vacuum electroslag remelting technology; the electroslag remelting slag system adopts CaF2, CaO, Al2O3, SiO2 and MgO five-element slag system with a content ratio of 65:10:15:5:5 (%).

[0057] S2. Ingot forging: heating the ingot obtained in S1 to 1170°C-1190°C for forging, with a final forging temperature of 950°C, forging it into a cylindrical bar with a forging ratio of 4-10.

[0058] S3, solution treatment of the bar, returning the bar forged in S2 to the furnace and heating it to 1130℃~1150℃, using water as a cooling medium to achieve rapid cooling, thereby reducing harmful precipitated phases and achieving uniformity of the structure; specifically, the furnace temperature when the bar enters the furnace is 900℃, the holding time is 2.0min~5.0min / mm, and the temperature is raised to the target temperature at a rate of 150℃~250℃ / h.

[0059] S4, the first blank processing, the bar material is processed by drilling the inner hole and turning the outer circle to obtain the first processed blank 1, such as Figure 2As shown, a bell mouth with an opening angle of α is processed at the inner circle of the head of the first processed blank 1, and α can be preferably 46°; the technical requirements for the first blank processing include: drilling inner hole deviation ±0.5mm; turning outer diameter deviation of finished product ±1mm; flat ends, end face verticality ≤1mm; inner and outer surfaces are ground and polished to remove scratches, turning tool marks and other defects, surface roughness Ra ≤1.6μm; length deviation ±5mm; inner and outer circle concentricity ≤1mm. No bevel is processed in this process.

[0060] In this embodiment, the specifications of the first processed blank 1 obtained are φ357 mm (outer diameter) / φ65 mm (inner diameter)×700 mm (length).

[0061] S5. Non-destructive testing of blanks: After the blanks are processed, ultrasonic testing is carried out according to the requirements of GB / T6402 to ensure that they meet the requirements of quality grade 3.

[0062] S6, primary hole expansion, the heated billet is expanded once by a vertical hole expansion machine, and the primary hole expansion steps specifically include:

[0063] ① Preheat the resistance furnace, put the billet into the furnace when the furnace temperature is 950℃, and keep it warm for 3.0h~6.0h. In this implementation, the keeping time is 2.0h~4.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the soaking is 1.5~3.5min; the second heating power is 600kW~800kW, the frequency is 62~90Hz, the temperature reaches 1155℃~1180℃, and then it is taken out of the furnace;

[0064] ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200℃;

[0065] ③ After the blank is heated, the inner and outer surfaces are evenly coated with glass powder lubricant, and then the blank is placed in the reaming tube, and the reaming head is placed in the bell mouth of the blank head, and then the hole is expanded; the expansion speed is 130mm / s~180mm / s, and the expansion ratio ranges from 1.02 to 1.28; after expansion, the blank is cooled in water at above 900℃.

[0066] In this embodiment, specifically, the inner diameter of the reaming tube is selected to be 368.5 mm, the reaming head model is Φ60 / 173 mm, the reaming ratio is 1.21, and the reaming speed is 130-180 mm / s.

[0067] S7, the blank is processed again, and the outer circle of the blank after the hole expansion is turned and polished to obtain the following Figure 3The reprocessed blank 2 shown in the figure has a bell mouth with an angle of α' processed at the inner circle of the head of the reprocessed blank 2, and α' can be preferably 46°; a bevel angle of β is processed at the outer circle of the tail of the reprocessed blank 2, and β can be preferably 35°, and a fillet is processed at the connection between the bevel and the ingot body, and the radius R of the fillet is preferably 20mm. Check whether the inner hole has defects and clean the defects. If there are no defects in the inner hole, the inner hole does not need to be processed. Clean the cracks, folds, scars, deep pits and other defects on the inner and outer surfaces. The grinding depth, width and length ratio is greater than 1:5:10, and the corners are smoothly transitioned; the outer diameter deviation of the finished product is ±1mm; the two ends are flat heads, and the end face verticality is ≤1mm; the length deviation is ±5mm, and the concentricity of the inner and outer circles is ≤1mm; the inner and outer surface roughness after cleaning is Ra≤1.6μm.

[0068] S8, secondary hole expansion, the heated billet is used to complete the secondary hole expansion by a vertical hole expansion machine, the hole expansion speed is 150mm / s to 200mm / s, and the hole expansion ratio range is 1.05 to 1.35; the secondary hole expansion process specifically includes:

[0069] ① When the temperature of the electric furnace is 950℃, put it into the furnace and keep it warm for 2.0h~4.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the temperature is evenly heated for 1.0~2.5min; the second heating power is 600kW~800kW, the frequency is 65~100Hz, the temperature reaches 1160℃~1185℃, and then take it out of the furnace;

[0070] ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200°C;

[0071] ③ After the blank is heated, glass powder lubricant is evenly applied to the inner and outer surfaces, and then placed in the reaming tube, and then the reaming head is placed in the bell mouth above the blank, followed by reaming. The reaming speed is 150mm / s~200mm / s, and the reaming ratio ranges from 1.05 to 1.35.

[0072] In this embodiment, specifically, the inner diameter of the reaming tube is selected to be 368.5 mm, the reaming head model is Φ75~170 / 228 mm, the reaming ratio is 1.19, and the reaming speed is 150~200 mm / s.

[0073] S9, rough pipe extrusion, heating the blank after the secondary hole expansion in step S8 and then using a horizontal extruder to extrude the rough pipe. Specifically, the rough pipe extrusion process includes:

[0074] ① After the second hole expansion is completed, the blank is turned around and then transferred to the secondary electromagnetic induction heating furnace with a heating power of 500kW to 800kW and a frequency of 40 to 70Hz. It is heated to 1160℃ to 1200℃ before being taken out of the furnace;

[0075] ② The inner wall of the extrusion barrel is heated to 300℃~500℃, and the surface of the extrusion die and core rod is heated to 250℃~450℃;

[0076] ③ Apply glass powder on the inner and outer surfaces of the blank, and then transfer it to the extrusion cylinder. The inner diameter of the extrusion cylinder is 4.5mm to 10mm larger than the outer diameter of the blank, and a glass pad is placed at the entrance of the extrusion die;

[0077] ④ Heat the prepared tail pad to a temperature of 950℃~1060℃, place it at the tail of the billet, and extrude the tail pad together with the billet;

[0078] ⑤ The power system of the extruder makes the extrusion rod push the billet to move in the extrusion direction. The billet advances at a speed of 60mm / s to 130mm / s. The extrusion ratio of the rough tube is 2.5 to 12.5. The billet metal passes through the cavity composed of the core rod and the extrusion die to become a rough tube. The extruded rough tube is cooled in water at a temperature above 960°C to below 40°C.

[0079] In this embodiment, specifically, the inner diameter of the extrusion barrel is 375mm, the extrusion die is 279.1±0.2mm, the core rod is 216.3mm, the extrusion ratio is 3.01, the extrusion speed is 80-120mm / s, the pressure surplus is 30mm, the preheating temperature of the extrusion barrel is 320℃, and the preheating temperature of the extrusion die and the core rod is 260℃. After the extrusion is completed, the initial quality inspection can be carried out to check the size and the quality of the inner and outer surfaces. The outer diameter range is required to be: 271-275mm, the wall thickness range is: 28.5-31.5mm, the length is: 2500-2700mm, and the presence of delamination defects is detected.

[0080] like Figure 4 As shown, in order to enhance the smooth flow of metal, reduce the extrusion pressure, reduce extrusion defects and improve the quality of the rough pipe during the extrusion of the rough pipe, the extrusion die adopts a double-cone die 3, and the internal inlet of the double-cone die 3 is composed of two die angles, the die angle γ is 120°, and the die angle γ' is 30°; the sizing belt 4 of the extrusion die is 12mm long, and in addition, a fillet with a radius of 15mm is processed in the transition area between the die angle γ section and the die angle γ' section, and a fillet with a radius of 12mm is processed in the transition area between the die angle γ' and the sizing belt 4.

[0081] After the extrusion of the rough tube is completed, in order to ensure that the tail of the billet of about 25mm to 50mm can be smoothly extruded to form a rough tube without causing material waste, a tail pad is set at the tail of the billet. The material of the tail pad is carbon steel. The outer diameter of the tail pad is the same as the outer diameter of the billet, and the inner diameter of the tail pad is 4mm to 5mm larger than the inner diameter of the billet. The length of the tail pad is 100mm.

[0082] S10, solution treatment of the rough pipe, heating to temperature in stages in a chamber furnace and then water cooling; the solution treatment process is: heating at 980℃ for 1.5min~2.0min / mm, heating to 1140℃ at a rate of 100℃~150℃ / h for 2.5min~5.0min / mm, transferring to a water pool within 65S to use water as a cooling medium to achieve rapid cooling.

[0083] In this embodiment, specifically, the heating time at 980° C. is 1.5 min / mm, and the heating time at 1140° C. is 3.0 min / mm when the temperature is increased at a rate of 120° C. / h.

[0084] S11, cold rolling, using a pilger cold rolling mill for two to seven passes of cold rolling treatment, each pass deformation 30% to 60%, feed 2.6 to 5.6 mm / time, rolling speed 30 to 60 times / minute, and the last pass of cold rolling deformation is controlled at 30% to 50%; the intermediate tube after each cold rolling, first remove the cold rolling oil in the degreasing tank, then carry out the solution treatment of the intermediate tube, and then transfer to the mixed acid pickling tank for pickling to remove the oxide scale; the solution treatment process of the intermediate tube in the cold rolling stage is: 1150 ° C heating time 3.0min to 6.0min / mm, use water as the cooling medium to achieve rapid cooling.

[0085] In this embodiment, two cold rolling processes are performed, and the deformation process is: rough pipe φ273mm (diameter) × 30mm (wall thickness) - cold rolled intermediate pipe φ245mm (diameter) × 22mm (wall thickness) - cold rolled finished pipe φ219mm (diameter) × 12.7mm (wall thickness); the deformation amount of the first pass is 32.7%, and the deformation amount of the second pass is 46.6%. The feed amount is 3.6mm / time, and the rolling speed is 46 times / minute.

[0086] S12. Solution treatment of finished pipes. To ensure the quality of the pipe body, different treatment processes are used for solution treatment of finished pipes according to the pipe body model. Cold-rolled pipes with an inner diameter of 35 mm and above are heated to temperature and then water-cooled. The process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, and water is used as the cooling medium within 60S to achieve rapid cooling; cold-rolled pipes with an inner diameter of less than 35mm and a wall thickness of less than 5mm are heat treated in a protective atmosphere bright furnace annealing furnace. The process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, protective gas strong convection jet + water cooling jacket cooling.

[0087] The finished tube in this embodiment is treated with water cooling for solution treatment, and the process is as follows: heating at 1010°C for 3.5 min / mm, and rapid cooling is achieved within 60 seconds using water as a cooling medium.

[0088] S13, finishing, straightening, testing, surface treatment, flat head, packaging.

[0089] The prepared GH3625 high-temperature alloy seamless pipe with a specification of φ219 mm (diameter) × 12.7 mm (wall thickness) was subjected to performance testing, and 1# to 3# were randomly selected for testing. The test data are shown in Table 1.

[0090] Table 1. Performance test results of GH3625 high temperature alloy finished seamless pipe

[0091] Test items Rm (MPa) Rp0.2 (MPa) A（%） ASTM G28 A method intergranular corrosion Grain size 1# Measured value 859 377 63 0.45mm / year Level 5.5 2# Measured value 852 351 63 0.36mm / year Level 5.0 3# Measured value 883 389 57 0.28mm / year Level 5.0 Technical indicators ≥690 ≥276 ≥30 <0.9mm / year ≥3.0

[0092] The GH3625 high-temperature alloy pipe finished seamless pipe obtained according to the production process of the present invention has test results such as tensile strength Rm, Rp0.2 yield strength, elongation, grain size, corrosion rate of standard ASTM G28 A method, etc. that meet the technical index requirements.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A production process for GH3625 high temperature alloy pipe, characterized in that: It includes the following steps, performed in order: S1. Ingot smelting: the alloy material is smelted into ingots through vacuum induction melting, vacuum casting electrode, and vacuum electroslag remelting technology; S2. Ingot forging: heating the ingot to 1170°C to 1190°C for forging, with a final forging temperature of 950°C, forging it into a cylindrical bar with a forging ratio of 4 to 10; S3, solution treatment of the bar, heating the cylindrical bar back to the furnace to 1130℃~1150℃, using water as the cooling medium to achieve rapid cooling; the furnace temperature when the bar enters the furnace is 900℃, the holding time is 2.0min~5.0min / mm, and the temperature is raised to the target temperature at a rate of 150℃~250℃ / h; S4, the first blank processing, the bar material is drilled with an inner hole, the outer circle is turned, and the two ends are flattened to obtain a blank; a bell mouth with an opening angle of α is processed at the inner circle of the blank head; S5, non-destructive testing of the blank, performing ultrasonic testing on the blank obtained in S4; S6, primary hole expansion, using a vertical hole expander to expand the heated billet once; S7, process the blank again, turn the outer circle of the blank after the hole expansion, polish it, flatten the two ends, process the bell mouth with an angle of α' at the inner circle of the head of the blank, process the bevel angle with an angle of β at the outer circle of the tail, and process the fillet at the connection between the bevel and the ingot body; S8, secondary hole expansion, the billet heated to temperature is expanded by a vertical hole expander; S9, rough pipe extrusion, heating the billet after the secondary hole expansion in step S8 and then using a horizontal extruder to extrude the rough pipe; S10, solution treatment of the rough pipe, heating to temperature in stages in a chamber furnace and then water cooling; S11, cold rolling, using a pilger cold rolling mill for two to seven passes of cold rolling treatment, each pass deformation of 30% to 60%, feed amount 2.6 to 5.6 mm / time, rolling speed 30 to 60 times / minute, and the last pass of cold rolling deformation is controlled at 30% to 50%; the intermediate tube after each cold rolling is firstly removed from the cold rolling oil in the degreasing tank, and then the intermediate tube is solution treated, and then transferred to the mixed acid pickling tank for pickling to remove the oxide scale; the solution treatment process of the intermediate tube in the cold rolling stage is 1150 ° C heating time 3.0min to 6.0min / mm, and water is used as the cooling medium to achieve rapid cooling; S12, solution treatment of finished tubes, cold-rolled tubes with an inner diameter of 35mm or more are heated to temperature and then water-cooled, the process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, water is used as cooling medium to achieve rapid cooling within 60S; cold-rolled tubes with an inner diameter less than 35mm and a wall thickness of less than 5mm are heat-treated in a protective atmosphere bright furnace annealing furnace, the process is: 960℃~1030℃ heating time 3.0min~8.0min / mm, protective gas strong convection jet + water cooling jacket cooling; S13, finishing, straightening, testing, surface treatment, flat head, packaging; The composition of the GH3625 high-temperature alloy pipe is as follows by mass percentage: Mo: 8-10%, Nb: 3.25-4.00%, C: 0.003-0.065%, Cr: 20-23%, Fe≤5%, Cu≤0.30%, Al: 0.10-0.25%, Ti: 0.15-0.35%, Co≤1.0%, Si≤0.45%, Mn≤0.45%, S≤0.010%, P≤0.015%, B≤0.006%, Mg≤0.10%, W≤0.10%, and the rest is Ni and unavoidable impurities.

2. The production process of a GH3625 high temperature alloy pipe according to claim 1, characterized in that: The GH3625 high temperature alloy pipe is a seamless pipe with an outer diameter ranging from 19 mm to 325 mm and a wall thickness ranging from 1.5 mm to 40 mm; The seamless pipe has the following properties: tensile strength Rm≥690MPa, Rp0.2 yield strength≥276MPa, elongation≥30%, grain size≥3.0 grade, and corrosion rate according to standard ASTM G28 A method<0.9mm / year.

3. The production process of a GH3625 high temperature alloy pipe according to claim 1 or 2, characterized in that: In the S4, the bell mouth opening angle α processed at the inner circle of the head is 46°, the inner hole drilling deviation is ±0.5mm, and the outer diameter deviation of the finished outer circle is ±1mm; the end surface verticality at both ends is ≤1mm; the inner and outer surfaces are ground and polished to remove scratches and tool mark defects, the surface roughness Ra≤1.6μm, the blank length deviation is ±5mm, and the concentricity of the inner and outer circles is ≤1mm.

4. The production process of a GH3625 high temperature alloy pipe according to claim 3, characterized in that: The one-time hole enlarging step in S6 comprises: ①When the temperature of the electric furnace is 950℃, put the billet into the furnace and keep it warm for 3.0h~6.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the temperature is evenly heated for 1.5~3.5min; the second heating power is 600kW~800kW, the frequency is 62~90Hz, the temperature reaches 1155℃~1180℃, and then it is taken out of the furnace; ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200℃; ③ After the blank is heated, the inner and outer surfaces are evenly coated with glass powder lubricant, and then the blank is placed in the reaming tube, and the reaming head is placed in the bell mouth of the blank head, and then the hole is expanded; the expansion speed is 130mm / s~180mm / s, the expansion ratio ranges from 1.02 to 1.28, and after expansion, it is cooled in water above 900℃.

5. The production process of a GH3625 high temperature alloy pipe according to claim 4, characterized in that: In the S7, the opening angle α' of the bell mouth processed at the inner circle of the head is 46°, the processing angle β at the outer circle of the tail is 35°, and the radius R of the fillet processed at the connection between the bevel and the ingot body is 20mm; the outer diameter deviation of the finished product is ±1mm; the verticality of the end faces at both ends is ≤1mm; the length deviation is ±5mm, and the concentricity of the inner and outer circles is ≤1mm; check whether the inner hole has defects and clean the defects; clean the cracks, folds, scars, and deep pit defects on the inner and outer surfaces, the grinding depth-width-length ratio is greater than 1:5:10, and the edges and corners have a smooth transition. After cleaning, the roughness of all surfaces is Ra≤1.6μm.

6. The production process of a GH3625 high temperature alloy pipe according to claim 5, characterized in that: The secondary hole expansion step in S8 comprises: ① When the temperature of the electric furnace is 950℃, put it into the furnace and keep it warm for 2.0h~4.0h; transfer it to the electromagnetic induction heating furnace and heat it twice. The first heating power is 450kW~550kW, the frequency is 40~60Hz, the temperature reaches 1100℃~1150℃, and the temperature is evenly heated for 1.0~2.5min; the second heating power is 600kW~800kW, the frequency is 65~100Hz, the temperature reaches 1160℃~1185℃, and then take it out of the furnace; ② The outer diameter of the blank before expansion is 8mm to 15mm smaller than the inner diameter of the expansion tube, and the inner wall of the expansion tube is preheated to 200°C; ③ After the blank is heated, glass powder lubricant is evenly applied to the inner and outer surfaces, and then placed in the reaming tube, and then the reaming head is placed in the bell mouth above the blank, followed by reaming. The reaming speed is 150mm / s~200mm / s, and the reaming ratio ranges from 1.05 to 1.

35.

7. The production process of a GH3625 high temperature alloy pipe according to claim 6, characterized in that: The step of extruding the rough pipe in S9 includes: ① After the second hole expansion is completed, the blank is turned around and then transferred to the secondary electromagnetic induction heating furnace with a heating power of 500kW to 800kW and a frequency of 40 to 70Hz. It is heated to 1160℃ to 1200℃ and then taken out of the furnace; ② The inner wall of the extrusion barrel is heated to 300℃~500℃, and the surface of the extrusion die and core rod is heated to 250℃~450℃; ③ Apply glass powder on the inner and outer surfaces of the blank, and then transfer it to the extrusion cylinder. The inner diameter of the extrusion cylinder is 4.5mm to 10mm larger than the outer diameter of the blank, and a glass pad is placed at the entrance of the extrusion die; ④ Heat the prepared tail pad to a temperature of 950℃~1060℃, place it at the tail of the billet, and extrude the tail pad together with the billet; ⑤ The power system of the extruder makes the extrusion rod push the billet to move in the extrusion direction. The billet advances at a speed of 60mm / s to 130mm / s. The extrusion ratio of the rough tube is 2.5 to 12.

5. The billet metal passes through the cavity composed of the core rod and the extrusion die to become a rough tube. The extruded rough tube is cooled in water at a temperature above 960°C to below 40°C.

8. The production process of a GH3625 high temperature alloy pipe according to claim 7, characterized in that: The extrusion die adopts a double cone die, and the internal entrance of the double cone die is composed of two die angles, the die angle γ is 120°, and the die angle γ' is 30°; the length of the sizing zone of the extrusion die is 12mm; the fillet radius of the transition area between the die angle γ section and the die angle γ' section is 15mm, and the fillet radius of the transition area between the die angle γ' and the sizing zone is 12mm; The tail pad is made of carbon steel, the outer diameter of the tail pad is the same as the outer diameter of the blank, the inner diameter of the tail pad is 4mm to 5mm larger than the inner diameter of the blank, and the length of the tail pad is 100mm.

9. A production process for GH3625 high temperature alloy pipe according to any one of claims 4 to 8, characterized in that: The process of solution treatment of the rough pipe in S10 is: heating at 980℃ for 1.5min~2.0min / mm, heating to 1140℃ at a rate of 100℃~150℃ / h for 2.5min~5.0min / mm, and transferring to a water pool within 65s to achieve rapid cooling using water as a cooling medium.

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