Preparation process of bimetal composite tee joint

Abstract

The invention relates to the technical field of pipeline equipment, and provides a bimetal composite tee joint preparation process which comprises the following steps: S1, a hot-rolled composite plate is provided, the hot-rolled composite plate comprises a carbon steel base layer, a stainless steel composite layer and a transition layer located between the carbon steel base layer and the stainless steel composite layer, and the transition layer is made of AlFeMnNi series high-entropy alloy; s2, the hot-rolled composite plate is rolled and welded, and a tubular blank is obtained; s3, the tubular blank is subjected to hot press molding, and a tee joint blank is obtained; and S4, the tee joint blank is subjected to shaping treatment, and the bimetal composite tee joint is obtained. By means of the technical scheme, the problem that in the prior art, the double-metal composite tee joint is poor in corrosion resistance is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline equipment, in particular, to a preparation process of a bimetallic composite tee joint. BACKGROUND

[0002] As a connecting component in a fluid conveying system, the bimetallic composite tee joint is widely used in the fields of petroleum, chemical industry, offshore platform and nuclear power due to its good corrosion resistance. The bimetallic composite tee joint adopts a composite structure of base layer / overlay, that is, a corrosion-resistant material such as stainless steel is used as the overlay on the inner wall in contact with the conveying medium, and a high-strength material such as carbon steel is used as the base layer on the pressure-bearing main structure part. This structural design makes the bimetallic composite tee joint have good service performance and engineering application value.

[0003] However, in the actual preparation process of the bimetallic composite tee joint, due to the carbon atom concentration gradient between the carbon steel base layer and the stainless steel overlay, the carbon atoms in the carbon steel base layer will spontaneously migrate to the stainless steel overlay. This will form chromium carbide on the side of the stainless steel overlay with a higher chromium content, resulting in a decrease in the corrosion resistance of the stainless steel overlay.

[0004] In order to inhibit carbon migration during the preparation of the bimetallic composite tee joint and improve its corrosion resistance, the common methods in the prior art are as follows: (1) adjusting the chemical composition of the carbon steel base layer or the stainless steel overlay, for example, the invention with the authorization announcement number CN112981251B determines that the most suitable carbon content of the overlay is 0.02%~0.03% and the carbon content of the base layer is 0.02%~0.06%, so that the overlay has excellent corrosion resistance and the base layer has high toughness, but the fluctuation range of the carbon content of the overlay and the base layer is too narrow, the composition control is too strict, and high-precision smelting processes such as vacuum decarburization or electroslag remelting need to be used to achieve it; (2) setting an intermediate layer such as pure nickel or pure copper between the carbon steel base layer and the stainless steel overlay, for example, the invention patent application with the application publication number CN118061648A sets a pure nickel foil intermediate layer between the stainless steel plate and the carbon steel plate, which reduces the decrease in the corrosion resistance of the composite plate caused by the element diffusion between the stainless steel plate and the carbon steel plate, but in the long-term service process, the nickel foil is easy to form brittle intermetallic compounds with Fe, Cr and other elements, thereby increasing the risk of stress corrosion cracking. Therefore, in order to better inhibit carbon migration and improve the corrosion resistance of the bimetallic composite tee joint, a new preparation process of the bimetallic composite tee joint needs to be researched. SUMMARY

[0005] The present application proposes a preparation process of a bimetallic composite tee joint, thereby solving or at least alleviating one or more of the above-mentioned problems and other aspects in the prior art.

[0006] The technical solution of the present application is as follows: This invention proposes a preparation process for a bimetallic composite tee, comprising the following steps: S1. A hot-rolled composite plate is provided, the hot-rolled composite plate comprising a carbon steel base layer, a stainless steel cladding layer and a transition layer located between the carbon steel base layer and the stainless steel cladding layer, wherein the material of the transition layer comprises an AlFeMnNi high-entropy alloy. S2. The hot-rolled composite plate is rolled and welded to obtain a tubular billet; S3. The tubular blank is hot-pressed to obtain a tee blank; S4. The tee blank is shaped to obtain a bimetallic composite tee.

[0007] As a further technical solution, the preparation process of the hot-rolled composite plate includes the following steps: S11. Provides carbon steel plates, stainless steel plates, and AlFeMnNi series high-entropy alloy powders; S12. Spray the AlFeMnNi series high-entropy alloy powder onto the surface of the carbon steel plate or the stainless steel plate to obtain a high-entropy alloy layer. Then, assemble and seal the plate in the order of carbon steel plate, high-entropy alloy layer and stainless steel plate from bottom to top to obtain a hot-rolled composite plate blank. S13. The hot-rolled composite plate blank is hot-rolled to obtain the hot-rolled composite plate.

[0008] As a further technical solution, the preparation process of the AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder and Ni powder in equal atomic ratios to obtain the AlFeMnNi-based high-entropy alloy powder.

[0009] As a further technical solution, the preparation process of the AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder, Ni powder and Cu powder in equal atomic ratios to obtain the AlFeMnNi-based high-entropy alloy powder.

[0010] As a further technical solution, the ball mill rotates at a speed of 300-400 rpm for 60-72 hours.

[0011] As a further technical solution, in step S13, the rolling temperature of the hot rolling process is 1300~1350℃, and the total reduction rate is 60%~70%.

[0012] As a further technical solution, in step S3, the temperature of the hot pressing is 900~1020℃.

[0013] As a further technical solution, step S4 includes a conditioning process after the shaping process.

[0014] As a further technical solution, the quenching and tempering process includes quenching and tempering; The quenching temperature is 920~950℃, and the holding time is 20~40min; The tempering temperature is 500~530℃, and the holding time is 20~40min.

[0015] As a further technical solution, the thickness of the carbon steel base layer is 8~20mm; and / or The thickness of the stainless steel cladding is 4-8 mm; and / or The thickness of the transition layer is 50~100μm.

[0016] The beneficial effects of this invention are as follows: The AlFeMnNi high-entropy alloy transition layer in the hot-rolled composite plate of this invention can suppress carbon migration during the preparation of bimetallic composite tees, avoiding the formation of chromium carbides on the stainless steel cladding side with a higher chromium content, thereby ensuring the corrosion resistance of the bimetallic composite tee. Unlike existing technologies that adjust the chemical composition of the carbon steel base layer and stainless steel cladding or set a pure metal intermediate layer, the technical solution of this invention has the following advantages: (1) The present invention uses a specific AlFeMnNi high-entropy alloy as a transition layer material to effectively hinder carbon migration and ensure the corrosion resistance of the bimetallic composite tee. From the overall perspective, the slow diffusion effect in the dynamics of the high-entropy alloy and the lattice distortion effect in the structure increase the migration energy barrier of carbon atoms and reduce the diffusion rate of carbon atoms. From the perspective of the effect of each element, Al and Ni elements can reduce the carbon solubility in the local area, thereby reducing the activity of carbon atoms and hindering the diffusion of carbon atoms. Fe and Mn elements have a high affinity for carbon atoms and can further capture the migrating carbon atoms and prevent the carbon atoms from continuing to diffuse. The cocktail effect of each element effectively hinders carbon migration and ensures the corrosion resistance of the bimetallic composite tee.

[0017] (2) The transition layer of AlFeMnNi high-entropy alloy has a thermodynamic high-entropy effect, which makes the atoms at the interface more inclined to form solid solution structure rather than intermetallic compound, thereby avoiding stress corrosion cracking.

[0018] (3) The present invention does not have special requirements for the chemical composition of the base carbon steel plate and the cladding stainless steel plate, and the raw materials are readily available, which broadens the application scope of the bimetallic composite tee preparation process of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be understood that, unless the context clearly indicates otherwise, the terms “comprising,” “including,” or “having” as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, as used herein, “comprising” and / or “including” indicate the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof.

[0021] In this application, the numerical range indicated by "~" refers to the range of values ​​specified as the lower and upper limits, respectively, before or after the term. When multiple values ​​for the upper or lower limit of any numerical range are mentioned, the range disclosed herein can be understood as a range with any one of the mentioned upper limits as its upper limit and any one of the mentioned lower limits as its lower limit.

[0022] Shear performance is one of the mechanical properties that determines the safety and reliability of bimetallic composite tees during service. Insufficient shear performance will make the composite a weak point. Under long-term stress, delamination may gradually expand from the initial stage. Once the stainless steel cladding separates from the carbon steel base layer, corrosive media will enter the delamination gaps, corroding the carbon steel base layer and causing perforation and leakage in the bimetallic composite tee. Therefore, how to further improve the shear performance of bimetallic composite tees while effectively suppressing carbon migration and ensuring their corrosion resistance is another technical challenge.

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preparation process of the bimetallic composite tee according to the embodiments of the present invention will be described in detail below.

[0024] According to one aspect of the present invention, a process for preparing a bimetallic composite tee is provided, comprising the following steps: S1. Provide hot-rolled composite plate, which includes a carbon steel base layer, a stainless steel cladding layer, and a transition layer between the carbon steel base layer and the stainless steel cladding layer. The material of the transition layer includes AlFeMnNi high-entropy alloy.

[0025] This invention selects carbon steel as the base material of the hot-rolled composite plate. Carbon steel has good strength and toughness, providing basic structural support for the bimetallic composite tee. Stainless steel is selected as the cladding material; its corrosion resistance allows the bimetallic composite tee to be used in corrosive environments. An AlFeMnNi high-entropy alloy is selected as the transition layer material, which can suppress carbon migration during the preparation of the bimetallic composite tee and ensure corrosion resistance. Due to the presence of the transition layer, this invention has no special requirements on the chemical composition of the base carbon steel plate and the cladding stainless steel plate, the raw materials are readily available, and the application range of the preparation process is broadened. The AlFeMnNi high-entropy alloy refers to a high-entropy alloy whose elements include Al, Fe, Mn, and Ni. In addition to the above elements, it may also include other elements that can form high-entropy alloys, such as Co and Cr. The atomic ratio of each element in the AlFeMnNi high-entropy alloy is 5%~35%.

[0026] In one embodiment of the present invention, the thickness of the carbon steel base layer is 8~20mm; and / or The thickness of the stainless steel cladding is 4~8mm; and / or The thickness of the transition layer is 50~100μm.

[0027] S2. The hot-rolled composite plate is rolled and welded to obtain a tubular blank.

[0028] This invention involves bending a hot-rolled composite sheet into a cylindrical shape on a plate rolling machine. After rolling, it is welded, using either gas metal arc welding (GMAW) or gas tungsten arc welding (GTAW). Following welding, any surface defects found in the tubular blank are repaired.

[0029] S3. Hot pressing is performed on the tubular blank to obtain a tee blank.

[0030] The hot pressing temperature of this invention is 900~1020℃. During hot pressing, the tubular blank is placed in a heating furnace for heating. After exiting the furnace, the tubular blank is placed in a forming die for pressing and forming, so that the branch pipe protrudes and forms a bulge, thus obtaining a tee blank.

[0031] S4. The tee blank is shaped to obtain a bimetallic composite tee.

[0032] This invention utilizes a cutting tool to make a hole at the end of the branch pipe of the tee blank. After removing the burrs from the hole, the hole is drawn and shaped until the size of the branch pipe opening meets the requirements. Finally, a jig is used for shaping to obtain a bimetallic composite tee.

[0033] In one embodiment of the present invention, the shaping process further includes a quenching and tempering process, which includes quenching and tempering. The quenching temperature is 920~950℃, and the holding time is 20~40min; the tempering temperature is 500~530℃, and the holding time is 20~40min.

[0034] In this invention, the heat treatment can eliminate the internal stress generated by the shaping process, effectively reduce the deformation of the bimetallic composite tee caused by stress release, improve the dimensional accuracy of the product, and ensure the dimensional stability of the bimetallic composite tee during long-term use.

[0035] In one embodiment of the present invention, the preparation process of the hot-rolled composite plate includes the following steps: S11 provides carbon steel plates, stainless steel plates, and AlFeMnNi-based high-entropy alloy powders.

[0036] In this invention, the carbon steel can be selected from commonly used steels in the field, and its composition meets the standard of GB / T 3274-2017 "Hot-rolled steel plates and strips of carbon structural steel and low alloy structural steel", preferably Q345 carbon steel; the stainless steel can be selected from commonly used steels in the field, and its composition meets the standard of GB / T 4237-2015 "Hot-rolled steel plates and strips of stainless steel", preferably austenitic stainless steel, more preferably 316 stainless steel; the AlFeMnNi high-entropy alloy powder can be commercially available powder or self-made powder, and this invention has no special requirements on the morphology of the AlFeMnNi high-entropy alloy powder.

[0037] S12. Spray AlFeMnNi series high-entropy alloy powder onto the surface of carbon steel plate or stainless steel plate to obtain a high-entropy alloy layer. Then, assemble and seal the plate in the order of carbon steel plate, high-entropy alloy layer and stainless steel plate from bottom to top to obtain hot-rolled composite plate blank.

[0038] When spraying AlFeMnNi-based high-entropy alloy powder according to this invention, thermal spraying, plasma spraying, or cold spraying can be used. Since cold spraying does not require a heat source and virtually no phase transformation or oxidation occurs during powder deposition, cold spraying is the preferred method. After assembling the blanks, the edges of the assembled plates are sealed using gas metal arc welding (GMAW) or gas tungsten arc welding (GTAW) to form a closed hot-rolled composite slab.

[0039] S13. The hot-rolled composite plate blank is hot-rolled to obtain a hot-rolled composite plate.

[0040] This invention involves feeding a hot-rolled composite plate billet into a heating furnace for heating at a rate controlled at 5-10°C / min. During heating, thermocouples are used to monitor the temperature of different parts of the billet in real time to ensure uniform temperature rise across all parts. Once the billet reaches the rolling temperature, it is held at that temperature for 20-30 minutes before rolling. The rolling temperature for hot rolling is 1300-1350°C. Before rolling, the rolls of the hot rolling mill are preheated to 200-300°C to reduce the temperature difference between the rolls and the billet. During hot rolling, the total reduction rate is 60%-70%, with the reduction rate in the first pass controlled at 15%-20%, and the reduction rate gradually decreasing in subsequent passes. The rolling speed is 0.5-1.5 m / s. After rolling, the billet is air-cooled to room temperature to obtain the hot-rolled composite plate.

[0041] In one embodiment of the present invention, the preparation process of AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder and Ni powder in equal atomic ratios to obtain AlFeMnNi-based high-entropy alloy powder.

[0042] Gas atomization, water atomization, plasma rotating electrode atomization, and mechanical alloying are commonly used methods for preparing high-entropy alloy powders. Mechanical alloying involves mixing elemental metal powders and then ball milling them in a high-energy ball mill. Through the impact, compression, and shearing of the grinding balls, the powder undergoes repeated cold welding and fracture, ultimately achieving alloying at the atomic scale. The entire preparation process is simple and the equipment cost is low; therefore, this invention employs mechanical alloying to prepare AlFeMnNi-based high-entropy alloy powders. During preparation, ball milling is performed under a vacuum argon atmosphere using stainless steel balls and a stainless steel container, with a ball-to-material mass ratio of 8-12:1. This invention successfully prepared AlFeMnNi high-entropy alloy powders via mechanical alloying, and its phase structure is identical to publicly reported phase structures, exhibiting a two-phase structure of B2 and FCC phases. This invention uses AlFeMnNi high-entropy alloy powders to prepare hot-rolled composite plates, obtaining an AlFeMnNi high-entropy alloy transition layer. The AlFeMnNi high-entropy alloy transition layer can, on the one hand, enhance the carbon migration barrier and reduce the diffusion rate through the slow diffusion effect of kinetics and the effect of structural lattice distortion; on the other hand, the cocktail effect of each element can further enhance the carbon barrier effect, effectively hinder carbon migration, and ensure the corrosion resistance of the bimetallic composite tee.

[0043] In one embodiment of the present invention, the preparation process of AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder, Ni powder and Cu powder in equal atomic ratios to obtain AlFeMnNi-based high-entropy alloy powder.

[0044] This invention also prepared AlFeMnNiCu high-entropy alloy powder by mechanical alloying, whose phase structure is the same as the publicly reported phase structure, both being a two-phase structure of BCC and FCC phases. During the preparation of the hot-rolled composite plate, due to the large positive enthalpy of mixing of Cu, it easily forms Cu-rich regions. These Cu-rich regions hinder dislocation movement, forming a reinforcing network and increasing strength, thereby effectively bearing and transmitting shear loads, further improving the shear performance of the bimetallic composite tee.

[0045] In one embodiment of the present invention, when preparing AlFeMnNi-based high-entropy alloy powder, the ball milling speed is 300~400 rpm and the time is 60~72 h. For example, the speed can be 300 rpm, 350 rpm, or 400 rpm; the time can be 60 h or 72 h, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] In this invention, when the ball milling speed is 300~400 rpm and the time is 60~72 h, the various elemental powders can be fully mixed, promoting element diffusion. This avoids the uneven composition of the high-entropy alloy caused by too low a speed or insufficient time, and also avoids the excessive fineness and severe agglomeration of the powder caused by too high a speed or too long time.

[0047] The fabrication process of a bimetallic composite tee according to the present invention will be described in detail below with reference to examples. The embodiments of the present invention described below can be modified in various ways, therefore the scope of the invention should not be construed as limited to the embodiments described in detail below. The embodiments are provided to help those skilled in the art to more easily understand the present invention.

[0048] In the examples below, the median particle size of Al powder, Fe powder, Mn powder, Ni powder and Cu powder is 40 μm.

[0049] Example 1 A fabrication process for a bimetallic composite tee includes the following steps: S1. Provide hot-rolled composite plate, which includes an 8mm thick Q345 carbon steel base layer, a 4mm thick 316 stainless steel cladding layer and a 50μm thick AlFeMnNi high-entropy alloy transition layer located between the Q345 carbon steel base layer and the 316 stainless steel cladding layer. S2. The hot-rolled composite plate is rolled into a cylindrical shape on a plate rolling machine, and then welded by tungsten inert gas welding to obtain a tubular blank. S3. Place the above tubular blank into a heating furnace and heat it to 900°C. After taking it out of the furnace, place the tubular blank into a forming die and press it to form a bulge, so that the branch pipe protrudes and forms a bulge, thus obtaining a tee blank. S4. Using a cutting machine, make a hole at the end of the branch pipe of the above-mentioned tee blank. After removing the burrs at the hole opening with a grinding wheel, draw and shape the hole opening. Use a jig to shape it. After shaping, perform quenching and tempering treatment (during quenching and tempering treatment, the quenching temperature is 920℃ and the holding time is 40min; the tempering temperature is 500℃ and the holding time is 40min) to obtain a bimetallic composite tee.

[0050] The manufacturing process of the above-mentioned hot-rolled composite plate includes the following steps: S11 offers Q345 carbon steel plate, 316 stainless steel and AlFeMnNi high-entropy alloy powder; The preparation process of AlFeMnNi high-entropy alloy powder includes the following steps: Al powder, Fe powder, Mn powder and Ni powder with equal atomic ratio are ball-milled in a planetary high-energy ball mill under vacuum argon atmosphere protection, using stainless steel balls and stainless steel jars, with a ball-to-material mass ratio of 8:1, and ball-milled at 300 rpm for 72 h to obtain AlFeMnNi high-entropy alloy powder. S12. AlFeMnNi high-entropy alloy powder is sprayed onto the surface of Q345 carbon steel plate by cold spraying to obtain a high-entropy alloy layer. The plate is assembled in the order of Q345 carbon steel plate, high-entropy alloy layer and 316 stainless steel plate from bottom to top. After assembly, the edges of the assembled plate are sealed by tungsten inert gas welding to form a closed hot-rolled composite billet. S13. The hot-rolled composite billet is sent to a heating furnace for heating at a heating rate of 5℃ / min to 1300℃. After heating, it is held at the temperature for 30 minutes before rolling. Before rolling, the rolls of the hot rolling mill are preheated to 200℃. The total reduction rate of rolling is 60%, the reduction rate of the first pass is 15%, and the reduction rate of subsequent passes gradually decreases. There are a total of 5 passes, and the rolling speed is 1.5m / s. After rolling, it is air-cooled to room temperature to obtain a hot-rolled composite plate.

[0051] Example 2 A fabrication process for a bimetallic composite tee includes the following steps: S1. Provide hot-rolled composite plate, which includes a 20mm thick Q345 carbon steel base layer, an 8mm thick 316 stainless steel cladding layer, and a 100μm thick AlFeMnNi high-entropy alloy transition layer located between the Q345 carbon steel base layer and the 316 stainless steel cladding layer. S2. The hot-rolled composite plate is rolled into a cylindrical shape on a plate rolling machine, and then welded by tungsten inert gas welding to obtain a tubular blank. S3. Place the above tubular blank into a heating furnace and heat it to 1020°C. After taking it out of the furnace, place the tubular blank into a forming die and press it to form a bulge, so that the branch pipe protrudes and forms a bulge, thus obtaining a tee blank. S4. Using a cutting machine, make a hole at the end of the branch pipe of the above-mentioned tee blank. After removing the burrs at the hole opening with a grinding wheel, draw and shape the hole opening. Use a jig to shape it. After shaping, perform quenching and tempering treatment (the quenching temperature is 950℃ and the holding time is 20min; the tempering temperature is 530℃ and the holding time is 20min) to obtain a bimetallic composite tee.

[0052] The manufacturing process of the above-mentioned hot-rolled composite plate includes the following steps: S11 offers Q345 carbon steel plate, 316 stainless steel and AlFeMnNi high-entropy alloy powder; The preparation process of AlFeMnNi high-entropy alloy powder includes the following steps: Al powder, Fe powder, Mn powder and Ni powder with equal atomic ratio are ball-milled in a planetary high-energy ball mill under vacuum argon atmosphere protection, using stainless steel balls and stainless steel jars, with a ball-to-material mass ratio of 12:1, and ball-milled at 400 rpm for 60 h to obtain AlFeMnNi high-entropy alloy powder. S12. AlFeMnNi high-entropy alloy powder is sprayed onto the surface of Q345 carbon steel plate by cold spraying to obtain a high-entropy alloy layer. The plate is assembled in the order of Q345 carbon steel plate, high-entropy alloy layer and 316 stainless steel plate from bottom to top. After assembly, the edges of the assembled plate are sealed by tungsten inert gas welding to form a closed hot-rolled composite billet. S13. The hot-rolled composite billet is sent to a heating furnace for heating at a heating rate of 10℃ / min to 1350℃. After heating, it is held at the temperature for 20 minutes before rolling. Before rolling, the rolls of the hot rolling mill are preheated to 300℃. The total reduction rate of rolling is 70%, the reduction rate of the first pass is 20%, and the reduction rate of subsequent passes gradually decreases. There are a total of 5 passes, and the rolling speed is 0.5m / s. After rolling, it is air-cooled to room temperature to obtain a hot-rolled composite plate.

[0053] Example 3 The difference between this embodiment and Embodiment 2 is that the transition layer of the hot-rolled composite plate is an AlFeMnNiCu high-entropy alloy. The preparation process of AlFeMnNiCu high-entropy alloy powder includes the following steps: Al powder, Fe powder, Mn powder, Ni powder and Cu powder with equal atomic ratios are ball-milled in a planetary high-energy ball mill under vacuum argon atmosphere protection, using stainless steel balls and stainless steel jars, with a ball-to-material mass ratio of 12:1, and ball-milled at 400 rpm for 60 hours to obtain AlFeMnNiCu high-entropy alloy powder.

[0054] Example 4 The only difference between this embodiment and Embodiment 3 is that the transition layer of the hot-rolled composite plate is an AlFeMnNiCo high-entropy alloy. The preparation process of AlFeMnNiCo high-entropy alloy powder includes the following steps: Al powder, Fe powder, Mn powder, Ni powder and Co powder with equal atomic ratios are ball-milled in a planetary high-energy ball mill under vacuum argon atmosphere protection, using stainless steel balls and stainless steel jars, with a ball-to-material mass ratio of 12:1, and ball-milled at 400 rpm for 60 hours to obtain AlFeMnNiCo high-entropy alloy powder.

[0055] Example 5 The only difference between this embodiment and Embodiment 3 is that the transition layer of the hot-rolled composite plate is an AlFeMnNiCr high-entropy alloy. The preparation process of the AlFeMnNiCr high-entropy alloy powder includes the following steps: Al powder, Fe powder, Mn powder, Ni powder and Cr powder with equal atomic ratios are ball-milled in a planetary high-energy ball mill under vacuum argon atmosphere protection, using stainless steel balls and stainless steel jars, with a ball-to-material mass ratio of 12:1, and ball-milled at 400 rpm for 60 hours to obtain AlFeMnNiCr high-entropy alloy powder.

[0056] Comparative Example 1 A fabrication process for a bimetallic composite tee includes the following steps: S1. Provide hot-rolled composite plate, which includes an 8mm thick Q345 carbon steel base layer and a 4mm thick 316 stainless steel cladding layer. S2. The hot-rolled composite plate is rolled into a cylindrical shape on a plate rolling machine, and then welded by tungsten inert gas welding to obtain a tubular blank. S3. Place the above tubular blank into a heating furnace and heat it to 900°C. After taking it out of the furnace, place the tubular blank into a forming die and press it to form a bulge, so that the branch pipe protrudes and forms a bulge, thus obtaining a tee blank. S4. Using a cutting machine, make a hole at the end of the branch pipe of the above-mentioned tee blank. After removing the burrs at the hole opening with a grinding wheel, draw and shape the hole opening. Use a jig to shape it. After shaping, perform quenching and tempering treatment (the quenching temperature is 920℃ and the holding time is 40min; the tempering temperature is 500℃ and the holding time is 40min) to obtain a bimetallic composite tee.

[0057] The manufacturing process of the above-mentioned hot-rolled composite plate includes the following steps: S11, available in Q345 carbon steel plate and 316 stainless steel; S12. Q345 carbon steel plate and 316 stainless steel plate are assembled into billets. After assembly, the edges of the assembled plates are sealed by tungsten inert gas welding to form a closed hot-rolled composite billet. S13. The hot-rolled composite billet is sent to a heating furnace for heating at a heating rate of 5℃ / min to 1300℃. After heating, it is held at the temperature for 30 minutes before rolling. Before rolling, the rolls of the hot rolling mill are preheated to 200℃. The total reduction rate of rolling is 60%, the reduction rate of the first pass is 15%, and the reduction rate of subsequent passes gradually decreases. There are a total of 5 passes, and the rolling speed is 1.5m / s. After rolling, it is air-cooled to room temperature to obtain a hot-rolled composite plate.

[0058] Comparative Example 2 The difference between this comparative example and Example 1 is that the transition layer of the hot-rolled composite plate is a FeCoNiCr high-entropy alloy, and the FeCoNiCr high-entropy alloy powder is a commercially available powder.

[0059] Experiment Example 1: Corrosion Resistance Test of Stainless Steel Cladding The corrosion rate of the stainless steel cladding in Example 1 and Comparative Examples 1 and 2 was tested using Method B in GB / T 4334-2020 "Corrosion of Metals and Alloys - Test Method for Intergranular Corrosion of Austenitic and Ferritic-Austenitic (Duplex) Stainless Steel". Sampling was conducted away from weld seams. The test results are shown in Table 1.

[0060] Table 1. Test results of corrosion resistance of stainless steel cladding

[0061] A comparison of Example 1 and Comparative Examples 1 and 2 shows that the present invention, using a specific AlFeMnNi-based high-entropy alloy as a transition layer, can effectively ensure the corrosion resistance of the bimetallic composite tee. Furthermore, compared to other high-entropy alloy systems such as FeCoNiCr high-entropy alloys, the AlFeMnNi-based high-entropy alloy better guarantees the corrosion resistance of the bimetallic composite tee, reducing the corrosion rate to as low as 0.7 g / (m²). 2 ·h) and below.

[0062] Experimental Example 2: Shear Strength Test The shear strength of the bimetallic composite tees in Examples 1-5 was tested according to GB / T 6396-2008 "Test Methods for Mechanical and Technological Properties of Composite Steel Plates". The shear stress rate was 5 N / (mm²). 2 ·s -1 When taking samples, avoid the weld seam. The test results are shown in Table 2 below.

[0063] Table 2 Shear strength test results

[0064] The comparison between Example 3 and Examples 2, 4 and 5 shows that, compared with other AlFeMnNi-based high-entropy alloys, the AlFeMnNiCu high-entropy alloy with a transition layer can further improve the shear performance of the bimetallic composite tee.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a bimetallic composite tee, characterized in that, Includes the following steps: S1. A hot-rolled composite plate is provided, the hot-rolled composite plate comprising a carbon steel base layer, a stainless steel cladding layer and a transition layer located between the carbon steel base layer and the stainless steel cladding layer, wherein the material of the transition layer comprises an AlFeMnNi high-entropy alloy. S2. The hot-rolled composite plate is rolled and welded to obtain a tubular billet; S3. The tubular blank is hot-pressed to obtain a tee blank; S4. The tee blank is shaped to obtain a bimetallic composite tee.

2. The preparation process of a bimetallic composite tee according to claim 1, characterized in that, The manufacturing process of the hot-rolled composite plate includes the following steps: S11. Provides carbon steel plates, stainless steel plates, and AlFeMnNi series high-entropy alloy powders; S12. Spray the AlFeMnNi series high-entropy alloy powder onto the surface of the carbon steel plate or the stainless steel plate to obtain a high-entropy alloy layer. Then, assemble and seal the plate in the order of carbon steel plate, high-entropy alloy layer and stainless steel plate from bottom to top to obtain a hot-rolled composite plate blank. S13. The hot-rolled composite plate blank is hot-rolled to obtain the hot-rolled composite plate.

3. The preparation process of a bimetallic composite tee according to claim 2, characterized in that, The preparation process of the AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder and Ni powder in equal atomic ratios to obtain the AlFeMnNi-based high-entropy alloy powder.

4. The preparation process of a bimetallic composite tee according to claim 2, characterized in that, The preparation process of the AlFeMnNi-based high-entropy alloy powder includes the following steps: ball milling Al powder, Fe powder, Mn powder, Ni powder and Cu powder in equal atomic ratios to obtain the AlFeMnNi-based high-entropy alloy powder.

5. The preparation process of a bimetallic composite tee according to claim 3 or 4, characterized in that, The ball mill operates at a speed of 300-400 rpm for 60-72 hours.

6. The preparation process of a bimetallic composite tee according to claim 2, characterized in that, In step S13, the rolling temperature of the hot rolling process is 1300~1350℃, and the total reduction rate is 60%~70%.

7. The preparation process of a bimetallic composite tee according to claim 1, characterized in that, In step S3, the temperature of the hot pressing is 900~1020℃.

8. The preparation process of a bimetallic composite tee according to claim 1, characterized in that, In step S4, the shaping process is followed by a conditioning process.

9. The preparation process of a bimetallic composite tee according to claim 8, characterized in that, The quenching and tempering process includes quenching and tempering; The quenching temperature is 920~950℃, and the holding time is 20~40min; The tempering temperature is 500~530℃, and the holding time is 20~40min.

10. The preparation process of a bimetallic composite tee according to claim 1, characterized in that, The carbon steel base layer has a thickness of 8~20mm; and / or The thickness of the stainless steel cladding is 4-8 mm; and / or The thickness of the transition layer is 50~100μm.

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