A device and method for regulating the solidification of a molten pool of a laser cladding coating on the inner wall of a steel pipe

Abstract

The application discloses a kind of laser cladding coating pool solidification regulation and control device and regulation and control method in steel pipe inner wall, the purpose of the present application is to solve the problem of insufficient regulation and control of traditional steel pipe component inner wall laser cladding protective coating pool solidification behavior, grain growth orientation is uncontrollable.The pool solidification regulation and control method of the present application: one, inner wall temperature controller and inner wall infrared temperature sensor are arranged on the inner wall of the steel pipe wall, outer wall temperature controller and outer wall infrared temperature sensor are arranged on the outer wall of the steel pipe wall;Two, laser cladding process is used to make alloy powder melt into pool, and the temperature controller is controlled to construct radial axial coupling pool temperature field;Three, by regulating and controlling radial axial coupling pool temperature field, induce columnar crystal directional growth, while controlling pool cooling rate.The application can accurately regulate and control coating columnar crystal growth orientation, synergistically improve coating shear strength, wear resistance and full-section performance uniformity, effectively prolong the service life of steel pipe, and is suitable for steel pipe component inner wall protection strengthening.

Description

Technical Field

[0001] This invention belongs to the field of laser additive manufacturing and surface strengthening technology of metal components, specifically relating to a molten pool solidification device and control method for laser cladding coating on the inner wall of steel pipe. Background Technology

[0002] As core components of industrial equipment, transmission systems, and fluid transport systems, steel pipe structures experience complex and harsh operating conditions on their inner walls. During long-term service, the inner walls of steel pipe structures are continuously subjected to high-temperature media erosion, high-pressure loads, and intense friction and axial shearing caused by the high-speed movement of the contact medium. This makes them highly susceptible to various defects such as wear failure, microcrack initiation, and shear deformation, directly leading to decreased operational stability and significantly shortening the effective service life of the steel pipe. To improve the overall wear resistance and shear resistance of the inner walls of steel pipes, the industry commonly employs surface strengthening processes to prepare protective coatings on the inner walls, thereby improving the mechanical properties and wear resistance of the inner walls. Currently, existing methods for strengthening the inner wall of steel pipes mainly include chrome plating, nitriding, and thermal spraying. However, all traditional processes have significant technical limitations. Specifically, chrome plating has weak adhesion to the substrate, making it prone to peeling and flaking during service, resulting in poor protective stability. Nitriding layers are too thin, limiting their load-bearing capacity and making it difficult to withstand high-intensity shear loads for extended periods, thus maintaining only a short service life. Traditional thermal spraying coatings have high porosity and insufficient structural density, exhibiting significant shortcomings in impact and shear resistance, making it difficult to meet the requirements for strengthening the inner wall of steel pipe components under high loads, long cycles, and complex working conditions.

[0003] Laser cladding technology uses high-energy lasers to instantaneously melt alloy powder and the substrate surface to form a dense protective coating with complete metallurgical bonding. It has significant advantages such as controllable coating thickness, low dilution rate, and interface bonding strength that is far superior to traditional thermal spraying and electroplating processes. It has become the mainstream research direction for strengthening the inner wall of steel pipes in recent years. However, when existing conventional laser cladding processes are used to prepare coatings for the inner wall of steel pipes, there are still multiple technical bottlenecks that are difficult to solve in a coordinated manner. First, traditional laser cladding processes for the inner walls of steel pipes rely solely on the natural heat dissipation due to the temperature difference between the inner and outer walls, resulting in only a single radial temperature gradient. After solidification, columnar crystals can only grow perpendicular to the inner wall of the steel pipe. Under high shear stress conditions, shear stress easily propagates along grain boundaries, leading to coating tearing and peeling. Second, traditional laser cladding processes lack synchronous temperature measurement modules for the inner and outer walls of the steel pipe, employing only open-loop processing with fixed process parameters. This makes it impossible to precisely control the radial and axial temperature differences and heat flow vectors of the molten pool, hindering control of the molten pool cooling rate and easily leading to problems such as coarse grains and compositional segregation. Furthermore, uneven heat distribution during cladding can cause significant fluctuations in the grain morphology and mechanical properties of the coating at different locations. Due to the lack of a real-time temperature monitoring mechanism, it is difficult to identify abnormal conditions such as local overheating and rapid cooling, easily generating internal defects such as porosity and thermal cracks, significantly increasing the probability of premature coating failure and further restricting the large-scale application of this process in the field of strengthening the inner walls of steel pipe components.

[0004] Based on the above analysis, the protective coatings prepared by existing laser cladding processes are insufficient to meet the shear resistance and wear resistance requirements of steel pipe inner walls under various working conditions. Therefore, this invention proposes a method for controlling the solidification of the molten pool in laser cladding coatings for steel pipe inner walls. This method abandons the single natural heat dissipation mode and instead sets segmented temperature control components on the inner and outer walls of the steel pipe. A radial-axial coupled temperature gradient is constructed using inner and outer wall temperature sensors and a closed-loop temperature control system to directionally induce columnar crystal growth. The grain tilt angle is controlled by the temperature difference ratio to improve the coating's shear resistance. Simultaneously, the solidification rate is controlled, the microstructure is refined, and segregation is reduced, while also improving wear resistance. This ensures uniform coating performance throughout the entire process, solves the core defects of traditional processes, and effectively extends the service life of the steel pipe. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of insufficient control over the solidification behavior of the molten pool, uncontrollable grain growth orientation, and poor microstructure uniformity of traditional laser cladding protective coatings on the inner wall of steel pipe components. This invention provides a device and method for controlling the solidification of the molten pool in laser cladding coatings on the inner wall of steel pipes. By controlling the heat flow direction of the molten pool through the temperature difference between the inside and outside of the steel pipe, the growth orientation of columnar crystals in the coating is controlled in a directional manner. Simultaneously, the solidification rate is controlled and the microstructure is refined, improving the wear resistance of the coating and ultimately obtaining a protective coating for the inner wall of steel pipes that combines high shear strength and excellent wear resistance.

[0006] The solidification control device for laser cladding coating on the inner wall of steel pipe of the present invention includes an outer wall temperature controller, an outer wall infrared temperature sensor, an inner wall temperature controller, an inner wall infrared temperature sensor, and a laser cladding head. The laser cladding head is set inside the steel pipe wall to perform laser cladding. An inner wall temperature controller and an inner wall infrared temperature sensor are set at the inner wall cladding pool of the steel pipe wall, and an outer wall temperature controller and an outer wall infrared temperature sensor are set at the outer wall cladding pool of the steel pipe wall.

[0007] The method for controlling the solidification of the molten pool in laser cladding coating on the inner wall of steel pipe according to the present invention is implemented according to the following steps:

[0008] Step 1: Perform surface pretreatment on the area to be clad on the inner wall of the steel pipe. Insert the laser cladding head into the inside of the steel pipe. Set an inner wall temperature controller and an inner wall infrared temperature sensor at the cladding pool on the inner wall of the steel pipe. Set an outer wall temperature controller and an outer wall infrared temperature sensor at the cladding pool on the outer wall of the steel pipe.

[0009] Step 2: Turn on the laser cladding head and powder feeding system. The powder feeding system contains alloy powder. The laser cladding process is used to melt the alloy powder to form a molten pool. The radial and axial coupled molten pool temperature field is constructed by the inner wall temperature controller and the outer wall temperature controller. The temperature is measured in real time by the inner wall infrared temperature sensor and the outer wall infrared temperature sensor.

[0010] Step 3: By adjusting the radial-axial coupled molten pool temperature field, columnar crystals are induced to grow in a directional manner, while the molten pool cooling rate is controlled to form a laser cladding coating on the inner wall of the steel pipe.

[0011] This invention employs segmented temperature control components deployed on the inner and outer walls of a steel pipe. Relying on a closed-loop temperature control system for real-time temperature measurement and dynamic adjustment, a radial-axial coupled temperature gradient field is constructed in the molten pool region to directionally induce the growth direction of columnar crystals. Simultaneously, by adjusting the temperature difference ratio and the molten pool cooling rate, controllable grain orientation and refined solidification structure are achieved. This invention can precisely control the growth orientation of columnar crystals in the coating, synergistically improving the coating's shear strength, wear resistance, and overall performance uniformity, effectively extending the service life of the steel pipe. It is suitable for the inner wall protection and strengthening of steel pipe components.

[0012] Compared with traditional laser cladding processes, the solidification control device and method for the laser cladding coating on the inner wall of steel pipe of this invention have the following advantages:

[0013] 1. Significantly improves the shear resistance of the coating: By constructing a radial-axial coupled temperature gradient, this invention breaks the traditional single radial heat dissipation grain growth mode. It can directionally induce columnar crystal growth direction according to needs, avoid the direct extension of shear stress along the grain boundary, and greatly improve the shear strength and anti-stripping ability of the coating, making it suitable for a variety of service conditions.

[0014] 2. Synergistic improvement of wear resistance and microstructure: By precisely controlling the cooling rate of the molten pool through a closed-loop temperature control system, grain coarsening and compositional segregation can be effectively suppressed, resulting in a refined solidification structure and uniform compositional distribution; combined with the directional growth of dense columnar crystal structure, the hardness and wear resistance of the coating are simultaneously improved, extending the wear-resistant service life.

[0015] 3. Improve coating quality and performance uniformity: Relying on synchronous temperature measurement and closed-loop control of the inner and outer walls, abnormal working conditions such as local overheating and sudden cooling can be identified and corrected in real time, effectively reducing cladding defects such as porosity and hot cracks; at the same time, a stable temperature difference field is maintained throughout the cladding process, ensuring that the grain orientation and mechanical properties of the coating are consistent throughout the steel pipe, and avoiding premature failure caused by local performance fluctuations.

[0016] 4. Excellent interfacial bonding strength: The coating is prepared by laser cladding, and the coating and the steel pipe substrate are completely metallurgically bonded. The bonding strength between the coating and the pipe wall is much higher than that of traditional processes such as chrome plating and thermal spraying. This solves the problem of easy peeling and detachment of traditional coatings and is suitable for service environments with high-intensity impact loads. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the solidification control device for the laser cladding coating on the inner wall of a steel pipe according to the present invention, wherein 1—steel pipe wall; 2—outer wall temperature controller; 3—outer wall infrared temperature sensor; 4—coating; 5—inner wall temperature controller; 6—inner wall infrared temperature sensor; 7—laser cladding head; 8—powder feeding pipe; 9—temperature control system; 10—outer wall temperature control signal transmission line; 11—inner wall temperature control signal transmission line; 12—inner wall temperature control power drive line; 13—outer wall temperature control power drive line;

[0018] Figure 2 This is a schematic diagram illustrating the mechanism of columnar crystal growth induced by the molten pool temperature gradient field in this invention. Detailed Implementation

[0019] Specific Implementation Method 1: The solidification control device for the laser cladding coating pool on the inner wall of the steel pipe in this implementation method includes an outer wall temperature controller 2, an outer wall infrared temperature sensor 3, an inner wall temperature controller 5, an inner wall infrared temperature sensor 6, and a laser cladding head 7. The laser cladding head 7 is installed inside the steel pipe wall 1 to perform laser cladding. The inner wall temperature controller 5 and the inner wall infrared temperature sensor 6 are installed at the inner wall cladding pool of the steel pipe wall 1, and the outer wall temperature controller 2 and the outer wall infrared temperature sensor 3 are installed at the outer wall cladding pool of the steel pipe wall 1.

[0020] In this embodiment, the outer wall temperature control component includes an outer wall temperature controller and an outer wall infrared temperature sensor. Its operating area is the outer wall of the steel pipe, applying directional temperature control to the outer wall of the molten pool solidification zone and collecting outer wall temperature data in real time. The inner wall temperature control component includes an inner wall temperature controller and an inner wall infrared temperature sensor, moving axially synchronously with the laser cladding head. Its operating area is the inner wall of the steel pipe, applying directional temperature control to the inner wall of the cladding zone and collecting inner wall temperature data in real time. The temperature control host monitors the temperature feedback from the inner and outer wall infrared temperature sensors in real time through the inner and outer wall temperature control signal transmission lines. It dynamically adjusts the output power of the inner and outer wall temperature controllers through the inner and outer wall temperature control power drive lines, constructing a stable radial-axial coupled temperature gradient field in the molten pool and solidification front region. This directionally controls the heat flow direction of the molten pool to induce the directional growth of columnar crystals, while simultaneously controlling the molten pool cooling rate within a preset range.

[0021] This embodiment constructs a controllable temperature gradient field to orient the growth orientation of columnar crystals in the coating, which can meet the shear resistance and wear resistance requirements of the protective coating on the inner wall of steel pipes under various service conditions. It is suitable for the inner wall surface strengthening treatment of various industrial pressure-bearing and fluid transportation steel pipe components.

[0022] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that a powder feeding tube 8 is connected to the laser cladding head 7.

[0023] In this embodiment, metal / alloy powder is conveyed through powder feeding pipe 8.

[0024] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the outer wall temperature controller 2, the outer wall infrared temperature sensor 3, the inner wall temperature controller 5, and the inner wall infrared temperature sensor 6 are respectively connected to the temperature control system 9 via transmission lines.

[0025] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that both the outer wall infrared temperature sensor 3 and the inner wall infrared temperature sensor 6 are non-contact infrared temperature measurement probes.

[0026] In this embodiment, the temperature measurement response time of the outer wall infrared temperature sensor 3 and the inner wall infrared temperature sensor 6 is no more than 100ms, the temperature measurement accuracy is ±5℃, and the sampling frequency is no less than 50Hz.

[0027] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that both the outer wall temperature controller 2 and the inner wall temperature controller 5 are equipped with a cooling module and a heating module. The cooling module is a semiconductor refrigeration chip; the heating module is a resistance wire heating rod or an infrared heater.

[0028] This embodiment achieves the cooling function through a semiconductor cooling chip and the heating function through a resistance wire heating rod or an infrared heater.

[0029] In this embodiment, the cooling module uses a semiconductor refrigeration module, which supports independent adjustment of cooling power in segments along the axial direction of the steel pipe, with a single-segment temperature control accuracy of ≤±5℃. The heating module uses a resistance preheating module or an infrared preheating module, with an effective heating coverage area covering an inner wall region of 5~30mm.

[0030] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the axial offset between the center of action of the outer wall temperature controller 2 and the center of action of the inner wall temperature controller 5 is 0~100mm.

[0031] In this embodiment, the axial offset refers to the distance between the outer wall temperature controller 2 and the inner wall temperature controller 5 along the axial direction of the steel pipe.

[0032] Specific Implementation Method Seven: The solidification control method for the laser cladding coating on the inner wall of the steel pipe in this implementation method is carried out according to the following steps:

[0033] Step 1: Perform surface pretreatment on the area to be clad on the inner wall of the steel pipe. Insert the laser cladding head 7 into the inside of the steel pipe. Set an inner wall temperature controller 5 and an inner wall infrared temperature sensor 6 at the cladding pool on the inner wall of the steel pipe 1. Set an outer wall temperature controller 2 and an outer wall infrared temperature sensor 3 at the cladding pool on the outer wall of the steel pipe 1.

[0034] Step 2: Turn on the laser cladding head 7 and the powder feeding system. The powder feeding system contains alloy powder. The laser cladding process is used to melt the alloy powder to form a molten pool. The radial and axially coupled molten pool temperature field is constructed by the inner wall temperature controller 5 and the outer wall temperature controller 2. The temperature is measured in real time by the inner wall infrared temperature sensor 6 and the outer wall infrared temperature sensor 3.

[0035] Step 3: By adjusting the radial-axial coupled molten pool temperature field, columnar crystals are induced to grow in a directional manner, while the molten pool cooling rate is controlled to form a laser cladding coating on the inner wall of the steel pipe.

[0036] This implementation method constructs a radial-axial coupled temperature field through misaligned temperature control of the inner and outer walls, which fundamentally determines the macroscopic orientation of columnar crystals growing at an angle towards the tube opening, and is the core control method.

[0037] In this embodiment, the temperature difference control range is 50℃~400℃, and the angle control range between the temperature gradient direction and the steel pipe axis direction is 10°~90°, which can cover the orientation requirements of columnar crystals in various scenarios such as approximately parallel axis, inclined growth and vertical inner wall.

[0038] Specific Implementation Method Eight: This implementation method differs from one of the specific implementation methods one to seven in that the alloy powder in step two is an iron-based self-fluxing alloy system, a nickel-based ceramic reinforced composite system, or a eutectic high-entropy alloy system.

[0039] The preferred alloy systems in this embodiment are FeCrBSiMo, FeCrBSi, and FeCoNiCrNb. 0.5 Mo 0.25 Eutectic high-entropy alloys and the like can maximize the directional control effect of temperature gradients, resulting in columnar crystals with more consistent orientation and more precise tilt angles.

[0040] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that it controls the cooling rate of the molten pool to be 10 using the inner wall temperature controller 5 and the outer wall temperature controller 2. 2 ~10 4 ℃ / s.

[0041] This embodiment controls the cooling rate of the molten pool to ensure a refined coating structure, resulting in fine columnar crystals and dispersed precipitates, thereby improving wear resistance.

[0042] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that step 3 controls the tilting growth angle of columnar crystals by adjusting the radial-axial coupled molten pool temperature field.

[0043] In this embodiment, during the solidification of the molten pool, the columnar crystals grow in the opposite direction to the direction of maximum heat flow, and their tilt angle θ (the angle with the radial direction of the steel pipe) satisfies a quantitative relationship with the radial-axial temperature difference:

[0044]

[0045] This implementation method adjusts the radial temperature difference ΔT. r With axial temperature difference ΔT a The ratio of the two values ​​can control the tilting growth angle of columnar crystals.

[0046] Specific Implementation Method Eleven: This implementation method differs from Specific Implementation Methods One through Ten in that when the powder feeding system contains Ni60+15%WC composite alloy powder, a laser cladding process is used to melt the alloy powder to form a molten pool. The laser power is controlled at 2200 W, the scanning speed at 300 mm / min, the powder feeding rate at 6 g / min, and the overlap rate at 35%. A radial-axial coupled molten pool temperature field is constructed through the inner wall temperature controller 5 and the outer wall temperature controller 2. The temperature is measured in real time through the inner wall infrared temperature sensor 6 and the outer wall infrared temperature sensor 3. The stable temperature range of the outer wall temperature control zone (i.e., the temperature measured by the outer wall infrared temperature sensor 3) is 520–570 ℃, and the stable temperature range of the inner wall temperature control zone (i.e., the temperature measured by the inner wall infrared temperature sensor 6) is 780–830 ℃.

[0047] Example 1: The solidification control device for the laser cladding coating pool on the inner wall of the steel pipe in this example includes an outer wall temperature controller 2, an outer wall infrared temperature sensor 3, an inner wall temperature controller 5, an inner wall infrared temperature sensor 6, a laser cladding head 7, and a temperature control system 9. The laser cladding head 7 is installed inside the steel pipe wall 1 to perform laser cladding. An inner wall temperature controller 5 and an inner wall infrared temperature sensor 6 are installed at the inner wall cladding pool of the steel pipe wall 1, and an outer wall temperature controller 2 and an outer wall infrared temperature sensor 3 are installed at the outer wall cladding pool of the steel pipe wall 1.

[0048] Both the outer wall temperature controller 2 and the inner wall temperature controller 5 are equipped with a cooling module and a heating module. The cooling module is a semiconductor refrigeration chip; the heating module is a resistance wire heating rod or an infrared heater.

[0049] The outer wall temperature controller 2 is connected to the control system 9 through the outer wall temperature control power drive line 13, the outer wall infrared temperature sensor 3 is connected to the control system 9 through the outer wall temperature control signal transmission line 10, the inner wall infrared temperature sensor 6 is connected to the control system 9 through the inner wall temperature control signal transmission line 11, and the inner wall temperature controller 5 is connected to the control system 9 through the inner wall temperature control power drive line 12.

[0050] The laser cladding coating solidification control device for the inner wall of steel pipe described in this embodiment comprises three parts: a laser cladding execution system, an inner and outer wall temperature control system, and a closed-loop temperature control system. Specifically: The laser cladding execution system, as the core execution unit for coating preparation, outputs a high-energy laser to melt alloy powder and form a molten pool with the substrate surface. Through synchronous powder feeding and axial advance, a dense protective coating is formed by layer-by-layer cladding on the inner wall of the steel pipe. The inner and outer wall temperature control system applies differentiated temperature control to the areas before and after the molten pool using inner and outer wall temperature control components. Simultaneously, it collects real-time temperature data from the inner and outer walls, providing a structural and temperature measurement basis for constructing a radial-axial coupled temperature gradient. The closed-loop temperature control system performs closed-loop control, dynamically adjusting the inner and outer wall temperature control outputs after receiving real-time temperature feedback. This maintains a stable temperature difference field and molten pool cooling rate, precisely controlling the columnar crystal growth orientation of the coating to ensure uniform coating microstructure and properties throughout the entire section.

[0051] Example 2: The solidification control method of the laser cladding coating molten pool on the inner wall of the steel pipe in this example is implemented according to the following steps:

[0052] Step 1: Pre-treat the area to be clad on the inner wall of the steel pipe by grinding, degreasing, and derusting. Insert the laser cladding head 7 into the steel pipe. Set an inner wall temperature controller 5 and an inner wall infrared temperature sensor 6 at the cladding pool on the inner wall of the steel pipe 1. Set an outer wall temperature controller 2 and an outer wall infrared temperature sensor 3 at the cladding pool on the outer wall of the steel pipe 1.

[0053] Step 2: Turn on the laser cladding head 7 and the powder feeding system. The powder feeding system contains Ni60+15%WC composite alloy powder. The laser cladding process is used to melt the alloy powder to form a molten pool. The laser power is controlled at 2200 W, the scanning speed at 300 mm / min, the powder feeding rate at 6 g / min, and the overlap rate at 35%. The radial temperature difference threshold is preset to 180℃, and the axial temperature difference threshold is preset to 90℃ (temperature difference ratio 0.5). The coating cooling rate is 10. 3 The temperature control parameter of ℃ / s is constructed by the inner wall temperature controller 5 and the outer wall temperature controller 2 to form a radial-axial coupled molten pool temperature field. The temperature is measured in real time by the inner wall infrared temperature sensor 6 and the outer wall infrared temperature sensor 3. The temperature stability range of the outer wall temperature control zone is 520~570 ℃, and the temperature stability range of the inner wall temperature control zone is 780~830 ℃. The system allows a temperature difference fluctuation tolerance range of ±15℃, and the axial offset distance between the inner and outer temperature control components is 50mm.

[0054] Step 3: By adjusting the radial-axial coupled molten pool temperature field, directional growth of columnar crystals is induced, while simultaneously controlling the molten pool cooling rate to 10. 3 At ℃ / s, a laser cladding coating is formed on the inner wall of the steel pipe.

[0055] This embodiment employs segmented temperature control components deployed on the inner and outer walls of the steel pipe. Relying on the real-time temperature measurement and dynamic power adjustment of the closed-loop temperature control system, a stable radial-axial coupled temperature gradient field is constructed in the molten pool region to directionally control the growth orientation of columnar crystals in the coating. Simultaneously, by precisely controlling the temperature difference ratio and the molten pool cooling rate, controllable grain orientation, grain refinement, and uniform coating performance are achieved simultaneously, synergistically improving the coating's shear strength, wear resistance, and service reliability.

[0056] The nickel-based composite coating prepared in this embodiment exhibits columnar crystals with an approximately 27° directional tilt, refined grains, uniform carbide dispersion, and few pores. The average interfacial shear strength of the coating is 325 MPa, significantly improving wear resistance and spalling resistance. The overall performance of the steel pipe is uniform, and its service life is significantly extended. If axial coupling temperature control is eliminated and only natural heat dissipation at room temperature exists, with only a single natural cooling radial temperature gradient, the vertical inner wall growth of the columnar crystals is easily torn along the grain boundaries by shear stress. This results in coarse grains, severe compositional segregation, a significant increase in the number of pores and hot cracks, poor interfacial shear strength, and a substantial decrease in the service reliability of the steel pipe.

[0057] This invention employs segmented temperature control components deployed on the inner and outer walls of a steel pipe. A closed-loop temperature control system measures and dynamically adjusts the temperature in real time, constructing a radial-axial coupled temperature gradient field in the molten pool region to directionally induce columnar crystal growth. Simultaneously, by adjusting the temperature difference ratio and the molten pool cooling rate, controllable grain orientation and refined solidification structure are achieved. This invention can precisely control the columnar crystal growth orientation of the coating, synergistically improving the coating's shear strength, wear resistance, and overall performance uniformity, effectively extending the service life of the steel pipe. It is suitable for strengthening the inner wall protection of steel pipe components.

Claims

1. A device for controlling the solidification of the molten pool in laser cladding coating on the inner wall of a steel pipe, characterized in that... The solidification control device for the laser cladding coating pool on the inner wall of the steel pipe includes an outer wall temperature controller (2), an outer wall infrared temperature sensor (3), an inner wall temperature controller (5), an inner wall infrared temperature sensor (6), and a laser cladding head (7). The laser cladding head (7) is set inside the steel pipe wall (1) for laser cladding. An inner wall temperature controller (5) and an inner wall infrared temperature sensor (6) are set at the inner wall cladding pool of the steel pipe wall (1), and an outer wall temperature controller (2) and an outer wall infrared temperature sensor (3) are set at the outer wall cladding pool of the steel pipe wall (1).

2. The device for controlling the solidification of the laser cladding coating pool on the inner wall of a steel pipe according to claim 1, characterized in that... A powder feeding tube (8) is connected to the laser cladding head (7).

3. The device for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 1, characterized in that... The outer wall temperature controller (2), the outer wall infrared temperature sensor (3), the inner wall temperature controller (5), and the inner wall infrared temperature sensor (6) are connected to the temperature control system (9) via transmission lines.

4. The device for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 1, characterized in that... Both the outer wall infrared temperature sensor (3) and the inner wall infrared temperature sensor (6) are non-contact infrared temperature probes.

5. The device for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 1, characterized in that... Both the outer wall temperature controller (2) and the inner wall temperature controller (5) are equipped with a cooling module and a heating module. The cooling module is a semiconductor refrigeration chip; the heating module is a resistance wire heating rod or an infrared heater.

6. The device for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 1, characterized in that... The axial offset between the center of action of the outer wall temperature controller (2) and the center of action of the inner wall temperature controller (5) is 0~100mm.

7. A method for controlling the solidification of the molten pool in laser cladding coating on the inner wall of steel pipe, characterized in that... The method for controlling the solidification of the molten pool of laser cladding coating on the inner wall of steel pipe is implemented according to the following steps: Step 1: Perform surface pretreatment on the area to be clad on the inner wall of the steel pipe. Insert the laser cladding head (7) into the inside of the steel pipe. Set an inner wall temperature controller (5) and an inner wall infrared temperature sensor (6) at the cladding pool on the inner wall of the steel pipe (1). Set an outer wall temperature controller (2) and an outer wall infrared temperature sensor (3) at the cladding pool on the outer wall of the steel pipe (1). Step 2: Turn on the laser cladding head (7) and the powder feeding system. The powder feeding system contains alloy powder. The laser cladding process is used to melt the alloy powder to form a molten pool. The radial and axial coupled molten pool temperature field is constructed by the inner wall temperature controller (5) and the outer wall temperature controller (2). The temperature is measured in real time by the inner wall infrared temperature sensor (6) and the outer wall infrared temperature sensor (3). Step 3: By adjusting the radial-axial coupled molten pool temperature field, columnar crystals are induced to grow in a directional manner, while the molten pool cooling rate is controlled to form a laser cladding coating on the inner wall of the steel pipe.

8. The method for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 7, characterized in that... In step two, the alloy powder is an iron-based self-fluxing alloy system, a nickel-based ceramic-reinforced composite system, or a eutectic high-entropy alloy system.

9. The method for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 7, characterized in that... The cooling rate of the molten pool is controlled to be 10 by the inner wall temperature controller (5) and the outer wall temperature controller (2). 2 ~10 4 ℃ / s.

10. The method for controlling the solidification of the molten pool of laser cladding coating on the inner wall of a steel pipe according to claim 7, characterized in that... Step 3 controls the tilting growth angle of columnar crystals by adjusting the radial-axial coupled molten pool temperature field.

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