Method for preparing GH3625 alloy seamless tube through welded tube blank

Abstract

The invention discloses a method for preparing a GH3625 alloy seamless tube through a welded tube blank, which sequentially comprises the following operation steps of: cleaning the surface of a GH3625 alloy plate strip, bending to form an alloy tube blank, welding to form a straight welded tube, deburring a welding seam, sizing, detecting flaws, carrying out solution treatment, cold rolling, and carrying out online ammonia decomposition bright annealing treatment to obtain an alloy primary tube; and the alloy primary pipe is sequentially subjected to straightening, flaw detection and cutting to obtain an alloy seamless pipe finished product, and the finished product is packaged and warehoused. According to the method disclosed by the invention, the alloy tube blank of any specification meeting the requirement of a cold rolling mill can be directly produced, so that cold rolling passes and intermediate annealing passes are reduced, the production efficiency of the GH3625 alloy seamless tube is greatly improved, and the production cost is reduced; a static recrystallization process induced by a'cold rolling and annealing treatment 'process is used, grains in a weld zone are refined, and low-sigma CSL grain boundaries mainly comprising annealing twin boundaries are regulated, so that various properties of the weld zone and a base metal structure tend to be consistent.

Description

Technical Field

[0001] The invention belongs to the technical field of metal pipe preparation, and in particular relates to a method for preparing a GH3625 alloy seamless pipe through a welded pipe blank. Background Art

[0002] GH3625 alloy pipes are widely used in gas turbine engines, combustion chambers, nuclear power equipment, chemical plant hardware, seawater special equipment and solar thermal power generation absorbers due to their excellent high temperature creep, strength durability, oxidation resistance and corrosion resistance below 650℃. At present, GH3625 alloy pipes are divided into two categories, one is GH3625 seamless pipes produced by hot extrusion, and the other is GH3625 welded pipes made by welding plate and strip after curling, also known as GH3625 welded pipes. Among them, GH3625 seamless pipes are mainly used in important pipeline systems with pressure requirements because of their overall processing and no welded joints. However, due to the characteristics of GH3625 alloy, such as high alloying degree, high resistance to thermal deformation, low process plasticity, and narrow thermal processing temperature range, it is difficult to form GH3625 alloy tube billets into GH3625 seamless pipes through hot perforation and hot extrusion, which seriously restricts the production and processing efficiency of GH3625 seamless pipes, resulting in very high production and processing costs of GH3625 seamless pipes. Therefore, the price of GH3625 seamless pipes is also very expensive. Compared with GH3625 seamless pipes, the production process of GH3625 welded pipes has the characteristics of short process, high efficiency, and low production cost. Therefore, GH3625 welded pipes are widely used. However, due to the large difference in organizational properties between the weld area and the parent material area of ​​the GH3625 welded pipe, the overall corrosion resistance of the GH3625 welded pipe is poor. During use, the weld area of ​​the GH3625 welded pipe is prone to fluid leakage due to local corrosion, thus limiting its use as only low-pressure fluid pipelines and structural parts. The present invention aims to propose a method for preparing a GH3625 alloy seamless pipe by using a welded pipe blank, in order to overcome the above technical problems. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects in the prior art and provide a method for preparing GH3625 alloy seamless pipes through welded pipe blanks. The method of the present invention can not only obtain the standard shape, size and surface quality of the required pipe through cold processing (including cleaning, bending, welding, deburring, sizing, and flaw detection) to achieve geometric seamlessness of the welded pipe, but also change the microstructure and mechanical properties of the weld zone of the GH3625 alloy welded pipe through deformation heat treatment technology (including solution treatment and online ammonia decomposition bright annealing treatment) to make it consistent with the parent material zone, thereby achieving physical seamlessness of the welded pipe; compared with the traditional hot extrusion method for preparing alloy pipe blanks, the method avoids the difficult-to-control links such as (hot) perforation, hot expansion, and hot extrusion of alloy forging rods, thereby effectively shortening the process flow. The process greatly improves the production and processing efficiency of GH3625 alloy seamless pipes; compared with the traditional hot extrusion method for preparing alloy tube billets, it not only has a simple process flow and high material utilization rate, but also can directly produce alloy tube billets of any specifications that meet the cold rolling mill, so as to reduce the number of cold rolling passes and intermediate annealing passes, greatly improving the production efficiency of GH3625 alloy seamless pipes and significantly reducing production costs; the static recrystallization process induced by the "cold rolling + annealing treatment" process can significantly regulate the microstructure of the weld zone of the welded pipe, by refining the grains in the weld zone of the welded pipe, regulating the low ΣCSL grain boundaries dominated by annealing twin boundaries, and at the same time improving the properties related to the weld zone and the grain boundaries, such as intergranular corrosion performance, oxidation resistance and mechanical properties, so that the properties of the weld zone and the parent material organization tend to be consistent.

[0004] To achieve the above purpose, the technical solution of the present invention is to design a method for preparing GH3625 alloy seamless pipe by welded pipe blank, and the operation steps are as follows:

[0005] S1: Clean the surface of GH3625 alloy plate and strip;

[0006] S2: Bending the cleaned GH3625 alloy sheet and strip into a GH3625 alloy tube blank;

[0007] S3: welding the GH3625 alloy tube blank into a GH3625 alloy straight seam welded tube, cooling it for standby use;

[0008] S4: Deburring the weld on the GH3625 alloy straight seam welded pipe;

[0009] S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0010] S6: Perform flaw detection on the GH3625 alloy straight seam welded pipe after sizing;

[0011] S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solid solution treatment. After the solid solution treatment and heat preservation are completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature;

[0012] S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment to obtain a GH3625 alloy blank pipe;

[0013] S9: subjecting the GH3625 alloy blank pipe to an online ammonia decomposition bright annealing treatment, and then continuously moving and advancing in a cooling system of circulating cooling water and cooling to room temperature to obtain a GH3625 alloy primary pipe;

[0014] S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the finished GH3625 alloy seamless pipes are packaged and stored.

[0015] The preferred technical solution is that the specific operation of step S2 is: the cleaned GH3625 alloy plate and strip is bent into a GH3625 alloy tube blank in a tube forming device in multiple steps.

[0016] Another preferred technical solution is that the specific operation of step S3 is to weld the GH3625 alloy tube blank into a GH3625 alloy straight seam welded tube by laser welding, the laser welding power is 4400-5300W, and the welding rate is 1-1.5m / min.

[0017] Another preferred technical solution is that the specific operation of step S4 is to deburr the weld positions on both the inner and outer sides of the GH3625 alloy straight seam welded pipe.

[0018] Another preferred technical solution is that in step S6 and step S10, eddy current flaw detection and ultrasonic flaw detection are used to perform flaw detection on the pipe.

[0019] Another preferred technical solution is that the specific operation of step S7 is to subject the GH3625 alloy straight seam welded pipe that has passed the flaw detection to solid solution treatment in an online ammonia decomposition heat treatment furnace, the solid solution treatment temperature is 1090-1210° C., and the solid solution treatment time is 30-80 min.

[0020] Another preferred technical solution is that in the step S8, the cold rolling deformation of the GH3625 alloy straight seam welded pipe during cold rolling to obtain the GH3625 alloy blank pipe is 20-65% and the rolling speed is 100-150 mm / min.

[0021] Another preferred technical solution is that in the step S9, the annealing temperature of the GH3625 alloy blank pipe during the online ammonia decomposition bright annealing treatment is 870-1030° C. and the holding time is 10-60 min.

[0022] Another preferred technical solution is that the straightening process in step S10 is specifically performed by directly straightening the bright annealed GH3625 alloy primary tube obtained in step S9 on a straightening machine.

[0023] The advantages and beneficial effects of the present invention are:

[0024] 1. A method for preparing a GH3625 alloy seamless pipe by using a welded pipe blank of the present invention comprises the following steps: cleaning, bending, welding, deburring, sizing, and flaw detection are performed on the GH3625 alloy plate and strip to obtain a qualified GH3625 alloy straight seam welded pipe; then the GH3625 alloy straight seam welded pipe is subjected to solution treatment, cooling by a circulating cooling water cooling system, cold rolling, and online ammonia decomposition bright annealing to obtain a GH3625 alloy primary pipe; and finally, the GH3625 alloy primary pipe is straightened, After flaw detection and cutting, the finished GH3625 alloy seamless pipe is obtained. The method of the present invention can not only obtain the standard shape, size and surface quality of the required pipe through cold processing (including cleaning, bending, welding, deburring, sizing, flaw detection) to achieve geometric seamlessness of the welded pipe, but also change the microstructure and mechanical properties of the weld zone of the GH3625 alloy welded pipe through deformation heat treatment technology (including solution treatment and online ammonia decomposition bright annealing treatment) to make it consistent with the parent material zone, thereby achieving physical seamlessness of the welded pipe.

[0025] 2. Compared with the traditional hot extrusion process for preparing alloy tube billets, the method of the present invention for preparing GH3625 alloy seamless tubes through welded tube billets avoids the difficult-to-control links such as (hot) perforation, hot expansion, and hot extrusion of alloy forging rods, thereby effectively shortening the process flow and greatly improving the production and processing efficiency of GH3625 alloy seamless tubes.

[0026] 3. The method of the present invention for preparing GH3625 alloy seamless pipe by welded pipe blank adopts nickel-based high-temperature alloy GH3625 welded pipe as pipe blank, and is processed into nickel-based high-temperature alloy GH3625 seamless pipe by appropriate cold rolling and heat treatment process. Compared with the traditional hot extrusion method for preparing alloy pipe blank, it not only has a simple process flow and high material utilization rate, but also can directly produce alloy pipe blanks of any specifications that meet the cold rolling mill, so as to reduce the number of cold rolling passes and intermediate annealing passes, greatly improve the production efficiency of GH3625 alloy seamless pipe, and significantly reduce the production cost.

[0027] 4. The method of the present invention for preparing GH3625 alloy seamless pipe by welded pipe blank, the produced GH3625 alloy seamless pipe has good overall uniformity of organization and basically consistent organization and performance, effectively eliminating the organization and performance differentiation phenomenon between the weld area and the base material area on the GH3625 alloy seamless pipe, ensuring that the GH3625 alloy seamless pipe has excellent corrosion resistance as a whole, making it suitable for use in places with high fluid pressure.

[0028] 5. The present invention provides a method for preparing GH3625 alloy seamless pipes through welded pipe billets. The static recrystallization process induced by the "cold rolling + annealing treatment" process can significantly regulate the microstructure of the weld zone of the welded pipe, by refining the grains in the weld zone of the welded pipe, regulating the low ΣCSL grain boundaries dominated by annealing twin boundaries, and improving the properties of the weld zone related to the grain boundaries, such as intergranular corrosion resistance, oxidation resistance and mechanical properties, so that the properties of the weld zone and the parent material organization tend to be consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The microstructure diagram of the GH3625 alloy straight seam welded pipe after the welding in step S3 of Example 2 is completed;

[0030] Figure 2 The room temperature tensile stress-strain curve diagram of the weld area and the base material area of ​​the GH3625 alloy straight seam welded pipe after the welding in step S3 in Example 2 is completed;

[0031] Figure 3 (a) is the microstructure diagram of the base material area of ​​the GH3625 alloy seamless tube prepared in Example 2;

[0032] Figure 3 (b) is the microstructure diagram of the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 2;

[0033] Figure 3 (c) is the microstructure diagram of the base material area of ​​the GH3625 alloy seamless tube prepared in Example 3;

[0034] Figure 3 (d) is the microstructure diagram of the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 3;

[0035] Figure 4 (a) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Example 2;

[0036] Figure 4 (b) is a distribution diagram of grain orientation difference angles in the weld zone of the GH3625 alloy seamless pipe prepared in Example 2;

[0037] Figure 4(c) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Example 3;

[0038] Figure 4 (d) is a distribution diagram of grain orientation difference angles in the weld zone of the GH3625 alloy seamless pipe prepared in Example 3;

[0039] Figure 5 (a) is a microstructure diagram of the base material region of the GH3625 alloy seamless tube prepared in Comparative Example 1;

[0040] Figure 5 (b) is a microstructure diagram of the weld area of ​​the GH3625 alloy seamless pipe prepared in Comparative Example 1;

[0041] Figure 5 (c) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Comparative Example 1;

[0042] Figure 5 (d) is a distribution diagram of grain orientation difference angles in the weld zone of the GH3625 alloy seamless pipe prepared in Comparative Example 1;

[0043] Figure 6 The room temperature tensile stress-strain curves of the base metal area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 2;

[0044] Figure 7 The room temperature tensile stress-strain curves of the base metal area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 3;

[0045] Figure 8 This is a room temperature tensile stress-strain curve of the base material area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Comparative Example 1. DETAILED DESCRIPTION

[0046] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0047] Example 1

[0048] The method of the present invention is used to prepare a GH3625 alloy seamless pipe, which includes the following steps:

[0049] S1: Clean the surface of GH3625 alloy plate and strip to remove the surface oxide layer and oil stains to improve welding quality;

[0050] S2: The cleaned GH3625 alloy sheet and strip are bent into GH3625 alloy tube blanks in a tube forming device in multiple steps;

[0051] S3: GH3625 alloy tube blanks were welded into GH3625 alloy straight seam welded tubes by laser welding, with a laser welding power of 4400W and a welding rate of 1.0m / min;

[0052] S4: Deburr the welds on both the inner and outer sides of the GH3625 alloy straight seam welded pipe;

[0053] S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0054] S6: Perform eddy current testing and ultrasonic testing on the sized GH3625 alloy straight seam welded pipe to check the welding quality of the weld;

[0055] S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solution treatment in an online ammonia decomposition heat treatment furnace. The solution treatment temperature is 1090°C and the solution treatment time is 30 minutes. After the solution treatment insulation is completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature to improve the cold working capacity of the weld zone of the GH3625 alloy straight seam welded pipe.

[0056] S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment, with a cold rolling deformation of 20% and a cold rolling speed of 100 mm / min to obtain a GH3625 alloy blank pipe;

[0057] S9: annealing the GH3625 alloy blank pipe in a continuous bright annealing furnace by an ammonia decomposition bright annealing process, the annealing temperature is 870°C, the holding time is 10 minutes, and after the holding is completed, the pipe is passed into a cooling system of circulating cooling water and continuously moved and pushed forward and cooled to room temperature to obtain a GH3625 alloy primary pipe;

[0058] S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the GH3625 alloy seamless pipes are packaged and stored, wherein the straightening operation is specifically: straightening the bright annealed GH3625 alloy primary pipes directly on the straightening machine.

[0059] Example 2

[0060] The method of the present invention is used to prepare a GH3625 alloy seamless pipe, which includes the following steps:

[0061] S1: Clean the surface of GH3625 alloy plate and strip to remove the surface oxide layer and oil stains to improve welding quality;

[0062] S2: The cleaned GH3625 alloy sheet and strip are bent into GH3625 alloy tube blanks in a tube forming device in multiple steps;

[0063] S3: GH3625 alloy tube blanks were welded into GH3625 alloy straight seam welded tubes by laser welding, with a laser welding power of 4700W and a welding rate of 0.9m / min;

[0064] S4: Deburr the welds on both the inner and outer sides of the GH3625 alloy straight seam welded pipe;

[0065] S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0066] S6: Perform eddy current testing and ultrasonic testing on the sized GH3625 alloy straight seam welded pipe to check the welding quality of the weld;

[0067] S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solution treatment in an online ammonia decomposition heat treatment furnace. The solution treatment temperature is 1130°C and the solution treatment time is 45 minutes. After the solution treatment insulation is completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature to improve the cold working capacity of the weld zone of the GH3625 alloy straight seam welded pipe;

[0068] S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment, with a cold rolling deformation of 35% and a cold rolling speed of 117 mm / min to obtain a GH3625 alloy blank pipe;

[0069] S9: annealing the GH3625 alloy blank pipe in a continuous bright annealing furnace using an ammonia decomposition bright annealing process, with an annealing temperature of 920°C and a holding time of 27 minutes. After the holding is completed, the pipe is passed through a cooling system of circulating cooling water and continuously moved and pushed forward and cooled to room temperature to obtain a GH3625 alloy primary pipe;

[0070] S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the GH3625 alloy seamless pipes are packaged and stored, wherein the straightening operation is specifically: straightening the bright annealed GH3625 alloy primary pipes directly on the straightening machine.

[0071] Example 3

[0072] The method of the present invention is used to prepare a GH3625 alloy seamless pipe, which includes the following steps:

[0073] S1: Clean the surface of GH3625 alloy plate and strip to remove the surface oxide layer and oil stains to improve welding quality;

[0074] S2: The cleaned GH3625 alloy sheet and strip are bent into GH3625 alloy tube blanks in a tube forming device in multiple steps;

[0075] S3: GH3625 alloy tube blanks are welded into GH3625 alloy straight seam welded tubes by laser welding, with a laser welding power of 5000W and a welding rate of 1.2m / min;

[0076] S4: Deburr the welds on both the inner and outer sides of the GH3625 alloy straight seam welded pipe;

[0077] S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0078] S6: Perform eddy current testing and ultrasonic testing on the sized GH3625 alloy straight seam welded pipe to check the welding quality of the weld;

[0079] S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solution treatment in an online ammonia decomposition heat treatment furnace. The solution treatment temperature is 1170°C and the solution treatment time is 60 minutes. After the solution treatment insulation is completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature to improve the cold working capacity of the weld zone of the GH3625 alloy straight seam welded pipe;

[0080] S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment, with a cold rolling deformation of 50% and a cold rolling speed of 135 mm / min to obtain a GH3625 alloy blank pipe;

[0081] S9: annealing the GH3625 alloy blank pipe in a continuous bright annealing furnace using an ammonia decomposition bright annealing process, with an annealing temperature of 970°C and a holding time of 45 minutes. After the holding is completed, the pipe is passed through a cooling system of circulating cooling water and continuously moved and pushed forward and cooled to room temperature to obtain a GH3625 alloy primary pipe;

[0082] S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the GH3625 alloy seamless pipes are packaged and stored, wherein the straightening operation is specifically: straightening the bright annealed GH3625 alloy primary pipes directly on the straightening machine.

[0083] Example 4

[0084] The method of the present invention is used to prepare a GH3625 alloy seamless pipe, which includes the following steps:

[0085] S1: Clean the surface of GH3625 alloy plate and strip to remove the surface oxide layer and oil stains to improve welding quality;

[0086] S2: The cleaned GH3625 alloy sheet and strip are bent into GH3625 alloy tube blanks in a tube forming device in multiple steps;

[0087] S3: GH3625 alloy tube blanks were welded into GH3625 alloy straight seam welded tubes by laser welding, with a laser welding power of 5300 W and a welding rate of 1.5 m / min;

[0088] S4: Deburr the welds on both the inner and outer sides of the GH3625 alloy straight seam welded pipe;

[0089] S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0090] S6: Perform eddy current testing and ultrasonic testing on the sized GH3625 alloy straight seam welded pipe to check the welding quality of the weld;

[0091] S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solution treatment in an online ammonia decomposition heat treatment furnace. The solution treatment temperature is 1210°C and the solution treatment time is 80 minutes. After the solution treatment insulation is completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature to improve the cold working capacity of the weld zone of the GH3625 alloy straight seam welded pipe;

[0092] S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment, with a cold rolling deformation of 65% and a cold rolling speed of 150 mm / min to obtain a GH3625 alloy blank pipe;

[0093] S9: annealing the GH3625 alloy blank pipe in a continuous bright annealing furnace using an ammonia decomposition bright annealing process, with an annealing temperature of 1030°C and a holding time of 60 minutes. After the holding is completed, the pipe is passed through a cooling system of circulating cooling water and continuously moved and pushed forward and cooled to room temperature to obtain a GH3625 alloy primary pipe;

[0094] S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the GH3625 alloy seamless pipes are packaged and stored, wherein the straightening operation is specifically: straightening the bright annealed GH3625 alloy primary pipes directly on the straightening machine.

[0095] Comparative Example 1

[0096] A GH3625 alloy seamless pipe is prepared by the following method, comprising the following steps:

[0097] H1: Clean the surface of GH3625 alloy plate and strip to remove the surface oxide layer and oil stains to improve welding quality;

[0098] H2: The cleaned GH3625 alloy sheet and strip are bent into GH3625 alloy tube blanks in a tube forming device in multiple steps;

[0099] H3: GH3625 alloy tube blanks are welded into GH3625 alloy straight seam welded tubes by laser welding. The laser welding power is 5000W and the welding speed is 1.2m / min.

[0100] H4: Deburr the welds on both the inner and outer sides of the GH3625 alloy straight seam welded pipe;

[0101] H5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine;

[0102] H6: Perform eddy current testing and ultrasonic testing on the sized GH3625 alloy straight seam welded pipe to check the welding quality of the weld;

[0103] H7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solution treatment in an online ammonia decomposition heat treatment furnace. The solution treatment temperature is 1150°C and the solution treatment time is 60 minutes. After the solution treatment insulation is completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature;

[0104] H8: The GH3625 alloy straight seam welded pipe treated in step H7 is straightened, inspected and cut in sequence to obtain a GH3625 alloy seamless pipe finished product, wherein the straightening operation is specifically: the bright annealed GH3625 alloy primary pipe is directly straightened on a straightening machine.

[0105] (I) Microstructure and performance testing of welded pipe base material area and weld area

[0106] The GH3625 alloy straight seam welded pipe obtained by welding in step S3 of Example 2, the GH3625 alloy seamless pipe prepared in Examples 1 to 4, and the GH3625 alloy seamless pipe prepared in Comparative Example 1 were subjected to microstructure and performance tests of the base material area and the weld area:

[0107] (1) Grind the sample used to observe the microstructure with 100# to 3000# water sandpaper;

[0108] (2) The ground sample was electropolished in a mixed solution of 80 ml CH3OH + 20 ml H2SO4 for 10 s;

[0109] (3) The sample was observed by electron backscatter diffraction (EBSD) under a FEI Nano SEM Nova 430 scanning electron microscope. The microstructure and orientation difference angle distribution of the treated sample were obtained by using the Channel 5 software installed on the EBSD system. The test results are shown in the attached Figure 1 , Attachment Figures 3 to 5 .

[0110] Figure 1 The microstructure diagram of the GH3625 alloy straight seam welded pipe after the welding in step S3 of Example 2 is shown in FIG. Figure 1 It can be seen that the weld area of ​​the alloy pipe is a typical cast structure, while the base material area is composed of uniform and fine equiaxed grains and a large number of annealing twins.

[0111] Figure 3 (a) is the microstructure diagram of the base material area of ​​the GH3625 alloy seamless pipe prepared in Example 2, Figure 3 (b) is the microstructure diagram of the weld zone of the GH3625 alloy seamless pipe prepared in Example 2, Figure 3 (c) is the microstructure diagram of the base material area of ​​the GH3625 alloy seamless pipe prepared in Example 3, Figure 3 (d) is the microstructure diagram of the weld zone of the GH3625 alloy seamless pipe prepared in Example 3, Figure 5 (a) is the microstructure diagram of the base material area of ​​the GH3625 alloy seamless pipe prepared in Comparative Example 1, Figure 5(b) is the microstructure diagram of the weld zone of the GH3625 alloy seamless pipe prepared in Comparative Example 1. It can be seen that the grain size of the parent material zone of the GH3625 alloy seamless pipe prepared in Example 2 is 11.57 μm, and the grain size of the weld zone is 9.44 μm. The grain size of the parent material zone of the GH3625 alloy seamless pipe prepared in Example 3 is 8.87 μm, and the grain size of the weld zone is 9.04 μm. The grain size of the parent material zone of the GH3625 alloy seamless pipe prepared in Comparative Example 1 is 43.93 μm, and the grain size of the weld zone is 14.76 μm. In addition , the grain size of the base material zone of the GH3625 alloy seamless pipe prepared in Example 1 was tested to be 17.85 μm, and the grain size of the weld zone was 22.31 μm. The grain size of the base material zone of the GH3625 alloy seamless pipe prepared in Example 4 was tested to be 7.88 μm, and the grain size of the weld zone was 8.65 μm. This indicates that the grains of the weld zone and the base material zone of the GH3625 alloy seamless pipe prepared in Examples 1 to 4 are fully refined after appropriate "cold rolling + annealing treatment", eliminating the organizational differences between the weld zone and the base material zone, and making the microstructures of the two zones tend to be consistent.

[0112] Figure 4 (a) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Example 2;

[0113] Figure 4 (b) is a distribution diagram of grain orientation difference angles in the weld zone of the GH3625 alloy seamless pipe prepared in Example 2; Figure 4 (c) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Example 3; Figure 4 (d) is a distribution diagram of grain orientation difference angles in the weld zone of the GH3625 alloy seamless pipe prepared in Example 3; Figure 5 (c) is a distribution diagram of grain orientation difference angles of the base material region of the GH3625 alloy seamless tube prepared in Comparative Example 1; Figure 5(d) is the grain orientation difference angle distribution diagram of the weld zone of the GH3625 alloy seamless pipe prepared in Comparative Example 1. It can be seen that the annealing twin boundary fraction of the parent material zone of the GH3625 alloy seamless pipe prepared in Example 2 is 40.12%, and the annealing twin boundary fraction of the weld zone is 42.09%. The annealing twin boundary fraction of the parent material zone of the GH3625 alloy seamless pipe prepared in Example 3 is 47.21%, and the annealing twin boundary fraction of the weld zone is 48.93%. The annealing twin boundary fraction of the parent material zone of the GH3625 alloy seamless pipe prepared in Comparative Example 1 is 56.92%, and the annealing twin boundary fraction of the weld zone is 57.34%. In addition, the annealing twin boundary fraction of the parent material zone of the GH3625 alloy seamless pipe prepared in Example 1 is 36.71%, and the annealing twin boundary fraction of the weld zone is 42.09%. The annealing twin boundary fraction of the GH3625 alloy seamless pipe prepared in Example 4 is 43.63% in the parent material zone, and 45.32% in the weld zone, indicating that direct high-temperature solid solution treatment of the GH3625 alloy seamless pipe prepared in Comparative Example 1 helps to increase the twin boundary fraction in the weld zone, but at the same time causes abnormal growth of the grain size, which is not conducive to eliminating the organizational differences between the parent material zone and the weld zone of the alloy welded pipe. After the GH3625 alloy seamless pipe prepared in Examples 1 to 4 is subjected to appropriate "cold rolling + annealing treatment", the annealing twin boundary content in the equiaxed grains in the parent material zone and the weld zone is relatively low, that is, the appropriate "cold rolling + annealing treatment" cooperates to effectively eliminate the organizational differences between the parent material zone and the weld zone of the alloy welded pipe, thereby achieving the purpose of the invention.

[0114] (II) Mechanical properties test

[0115] A portion of the GH3625 alloy straight seam welded pipe obtained by welding in step S3 of Example 2, the GH3625 alloy seamless pipe prepared in Examples 1 to 4, and the GH3625 alloy seamless pipe prepared in Comparative Example 1 were cut out from the weld area and the base material area for room temperature tensile tests:

[0116] (1) Each specimen is processed into a standard sheet tensile specimen according to the specimen requirements in GBT 228-2002 "National Standard for Tensile Specimens";

[0117] (2) Grind the sample prepared for room temperature tensile test with 100# to 400# water sandpaper;

[0118] (3) The room temperature tensile test (tensile rate of 1×10 –3 s –1 ), the room temperature tensile stress-strain curves of each sample are shown in the attached Figure 2 , Attachment Figures 6 to 8 .

[0119] Figure 2 The room temperature tensile stress-strain curve of the weld zone and the base material zone of the GH3625 alloy straight seam welded pipe after the welding in step S3 in Example 2 is shown in FIG. Figure 2 It can be seen that the tensile strength of the parent metal area is 913MPa, the yield strength is 542MPa, and the elongation after fracture is 24.8%, and the tensile strength of the weld area is 768MPa, the yield strength is 500MPa, and the elongation after fracture is 15.1%;

[0120] Figure 6 The room temperature tensile stress-strain curves of the base metal area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 2 are shown in FIG. Figure 6 It can be seen that the tensile strength of the parent metal area is 953MPa, the yield strength is 459MPa, and the elongation after fracture is 58.11%, and the tensile strength of the weld area is 961MPa, the yield strength is 480MPa, and the elongation after fracture is 46.11%;

[0121] Figure 7 The room temperature tensile stress-strain curves of the base metal area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Example 3 are shown in FIG. Figure 7 It can be seen that the tensile strength of the parent metal area is 902MPa, the yield strength is 559MPa, and the elongation after fracture is 46.11%, and the tensile strength of the weld area is 929MPa, the yield strength is 552MPa, and the elongation after fracture is 54.44%;

[0122] Figure 8 The room temperature tensile stress-strain curves of the base material area and the weld area of ​​the GH3625 alloy seamless pipe prepared in Comparative Example 1 are shown in FIG. Figure 8 It can be seen that the tensile strength of the parent metal area is 691MPa, the yield strength is 313MPa, and the elongation after fracture is 66.11%, and the tensile strength of the weld area is 695MPa, the yield strength is 271MPa, and the elongation after fracture is 65.77%;

[0123] In addition, the tensile strength of the base material zone of the GH3625 alloy seamless pipe prepared in Example 1 is 856 MPa, the yield strength is 421 MPa, and the elongation after fracture is 62.04%, and the tensile strength of the weld zone is 872 MPa, the yield strength is 433 MPa, and the elongation after fracture is 50.03%; while the tensile strength of the base material zone of the GH3625 alloy seamless pipe prepared in Example 4 is 956 MPa, the yield strength is 582 MPa, and the elongation after fracture is 40.2%, and the tensile strength of the weld zone is 964 MPa, the yield strength is 568 MPa, and the elongation after fracture is 35.4%.

[0124] It can be seen from the tensile strength, yield strength and elongation data of the weld zone and the parent material zone of the GH3625 alloy seamless pipe prepared in Examples 1 to 4 that, relative to the GH3625 alloy seamless pipe prepared in Comparative Example 1, the GH3625 alloy seamless pipe prepared by the method of the present invention in Examples 1 to 4 has very little difference in the room temperature mechanical properties of the parent zone and the weld zone of the alloy welded pipe after appropriate cold rolling and heat treatment, and the strength is greatly improved, which indicates that appropriate "cold rolling + annealing treatment" is beneficial to improving the mechanical properties of the parent material zone and the weld zone of the GH3625 alloy seamless pipe, eliminating the performance difference between the weld zone and the parent material zone, and achieving the purpose of the invention.

[0125] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing GH3625 alloy seamless pipe by welded pipe blank, characterized in that: The steps are as follows: S1: Clean the surface of GH3625 alloy plate and strip; S2: Bending the cleaned GH3625 alloy sheet and strip into a GH3625 alloy tube blank; S3: welding the GH3625 alloy tube blank into a GH3625 alloy straight seam welded tube, cooling it for standby use; S4: Deburring the weld on the GH3625 alloy straight seam welded pipe; S5: The GH3625 alloy straight seam welded pipe after deburring is sizing on a sizing machine; S6: Perform flaw detection on the GH3625 alloy straight seam welded pipe after sizing; S7: The GH3625 alloy straight seam welded pipe that has passed the flaw detection is subjected to solid solution treatment. After the solid solution treatment and heat preservation are completed, the GH3625 alloy straight seam welded pipe is continuously moved and pushed forward in the cooling system of circulating cooling water and cooled to room temperature; S8: cold rolling the GH3625 alloy straight seam welded pipe cooled to room temperature after solution treatment to obtain a GH3625 alloy blank pipe; S9: subjecting the GH3625 alloy blank pipe to an online ammonia decomposition bright annealing treatment, and then continuously moving and advancing in a cooling system of circulating cooling water and cooling to room temperature to obtain a GH3625 alloy primary pipe; S10: After straightening, flaw detection and cutting of the GH3625 alloy primary pipes, the finished GH3625 alloy seamless pipes are packaged and stored.

2. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: The specific operation of step S2 is: the cleaned GH3625 alloy plate and strip is bent into a GH3625 alloy tube blank in a tube forming device in multiple steps.

3. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: The specific operation of step S3 is to weld the GH3625 alloy tube blank into a GH3625 alloy straight seam welded tube by laser welding, the laser welding power is 4400-5300W, and the welding rate is 1-1.5m / min.

4. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: The specific operation of step S4 is to deburr the weld positions on both the inner and outer sides of the GH3625 alloy straight seam welded pipe.

5. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: In the step S6 and the step S10, eddy current flaw detection and ultrasonic flaw detection are used to perform flaw detection on the pipe.

6. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: The specific operation of step S7 is to perform solid solution treatment on the GH3625 alloy straight seam welded pipe that has passed the flaw detection in an online ammonia decomposition heat treatment furnace, the solid solution treatment temperature is 1090-1210° C., and the solid solution treatment time is 30-80 minutes.

7. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: In the step S8, the cold rolling deformation of the GH3625 alloy straight seam welded pipe to obtain the GH3625 alloy blank pipe is 20-65% and the rolling speed is 100-150 mm / min.

8. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: In the step S9, the annealing temperature of the GH3625 alloy blank pipe during the online ammonia decomposition bright annealing treatment is 870-1030° C. and the holding time is 10-60 min.

9. The method for preparing GH3625 alloy seamless pipe by welded pipe blank according to claim 1, characterized in that: The straightening process in step S10 is specifically performed by directly straightening the bright annealed GH3625 alloy primary tube obtained in step S9 on a straightening machine.

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