Process for processing corrosion-resistant aluminum alloy pipe through laser cladding

Abstract

The invention discloses a process for processing a corrosion-resistant aluminum alloy pipe through laser cladding, which comprises the following steps of: performing laser cladding on a formed aluminum alloy pipe, transmitting a laser beam to the surface of the aluminum alloy pipe, conveying cladding layer powder / alloy wires to a laser area, quickly melting the cladding layer powder / alloy wires and the surface of the aluminum alloy pipe together through the laser beam, and solidifying, thereby obtaining the corrosion-resistant aluminum alloy pipe. The cladding layer combined with the aluminum alloy pipe is formed on the surface of the aluminum alloy pipe, cladding layer powder / alloy wires are made of zinc or zinc alloy, the cladding layer serves as a sacrificial anode, a thin and compact oxide and hydroxide layer is formed on the surface of the aluminum alloy pipe, further oxidation reaction is effectively prevented, and the corrosion resistance and reliability of the aluminum alloy pipe are improved. And the laser cladding procedure can be accurately controlled by controlling the laser power of the laser beam, the spot diameter, the passing speed of the aluminum alloy pipe and the speed of conveying cladding layer powder / alloy wires, so that the cladding layer has the advantages of being small in dilution degree, compact in structure, good in combination with the aluminum alloy pipe and not prone to falling off.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy pipes, and in particular to a corrosion-resistant processing technology for aluminum alloy pipes. Background Art

[0002] Aluminum alloy tubes have the same pressure resistance and heat exchange capacity as copper tubes, but the cost is much lower than copper tubes. Therefore, aluminum alloy tubes are usually used as air conditioning pipes in the air conditioning field. However, aluminum alloy tubes have poor corrosion resistance and are easily corroded by moisture, oxygen, etc. in the air, which can cause the aluminum alloy tubes to fail and the air conditioning pipes to leak, thereby reducing the service life of the air conditioner.

[0003] Zinc (Zn) is a metal with moderate activity. Its natural corrosion resistance is not high. However, due to the relatively negative standard electrode potential of zinc, when zinc comes into contact with other metals (such as aluminum and copper) and is exposed to electrolytes (such as seawater or humid air), zinc will preferentially undergo oxidation reactions, thereby protecting other metals from corrosion, which makes it a commonly used sacrificial anode material. In addition, a thin and dense layer of oxides and hydroxides will form on the surface of zinc when it comes into contact with air. This film can effectively prevent further oxidation reactions.

[0004] In the prior art, the coating is usually processed on the surface of the substrate by spraying, electroplating or vapor deposition. However, the common processing technology has the defects that the bonding density between the coating and the substrate is not high and it is easy to fall off.

[0005] Therefore, how to effectively improve the corrosion resistance of aluminum alloy tubes, extend the service life of aluminum alloys, and improve the reliability of aluminum alloys has become an urgent problem to be solved in this field. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to provide a process for laser cladding processing of corrosion-resistant aluminum alloy tubes, so as to improve the corrosion resistance and reliability of the aluminum alloy tubes and extend their service life.

[0007] In order to achieve the above object, the present invention provides a process for laser cladding processing of corrosion-resistant aluminum alloy tubes, the process comprising:

[0008] hot extruding the aluminum alloy billet to form an aluminum alloy tube;

[0009] Laser cladding is performed on the formed aluminum alloy tube. First, the aluminum alloy tube is laid out to preset the laser scanning trajectory, and the laser beam is straightened and cleaned on the outer surface. Then, the laser beam emitting device is evenly distributed around the aluminum alloy tube and the laser beam is emitted corresponding to the scanning trajectory. The cladding layer powder / alloy wire is simultaneously transported to the area where the laser beam is located. The laser power of the laser beam is 3000-3500W, the spot diameter is 3-5mm, the passing speed of the aluminum alloy tube is 200-250m / min, and the speed of transporting the cladding layer powder / alloy wire is 40-60g / min. Then, the aluminum alloy tube after laser cladding is cooled through a water tank.

[0010] The aluminum alloy tube after laser cladding is subjected to finishing treatment.

[0011] Furthermore, the aluminum alloy tube includes an aluminum alloy smooth tube, and the finishing process is configured to perform coiling, online annealing, finishing, heat treatment and packaging and warehousing on the aluminum alloy smooth tube.

[0012] Furthermore, the aluminum alloy tube includes an aluminum alloy internally threaded tube, and the finishing process is configured to perform coiling, online annealing, internal thread forming, finishing, heat treatment and packaging and warehousing on the aluminum alloy internally threaded tube.

[0013] Furthermore, in the hot extrusion process, the aluminum alloy billet is gradient heated to 400∽450°C or 430∽470°C, and then extruded through a die with an extrusion ratio of ≥150, and the extruded aluminum alloy tube is cooled in a water tank.

[0014] Furthermore, in the coiling process, when the aluminum alloy tube is stretched, the stretching passes are adapted to the size of the aluminum alloy tube, and the elongation coefficient of each pass is 1.1 to 1.8, and the total deformation rate of the stretching is configured to be 35% to 85%.

[0015] Furthermore, in the heat treatment process, the aluminum alloy tube is placed in an annealing heating furnace, the temperature of the annealing heating furnace is set to 450-570° C., and the temperature is kept for 30-90 minutes to perform heat treatment on the aluminum alloy tube.

[0016] Furthermore, the cladding layer powder / alloy wire is composed of zinc or zinc alloy.

[0017] Furthermore, the laser beam emitting device is configured such that three laser cladding guns are evenly distributed around the aluminum alloy tube at an angle of 120°.

[0018] Furthermore, the laser beam emitting device is configured such that two laser cladding guns are evenly distributed around the aluminum alloy tube at an angle of 180°.

[0019] The process for laser cladding processing of corrosion-resistant aluminum alloy tubes provided by the present invention performs laser cladding on the formed aluminum alloy tube, and simultaneously transmits the cladding layer powder / alloy wire to the area where the laser beam is located while emitting a laser beam on the surface of the aluminum alloy tube, so that the laser beam quickly melts and solidifies the cladding layer powder / alloy wire together with the surface of the aluminum alloy tube, and forms a cladding layer combined with the aluminum alloy tube on the surface of the aluminum alloy tube, so that the cladding layer can protect the aluminum alloy tube.

[0020] At the same time, the cladding layer powder / alloy wire is formed of zinc or zinc alloy, so that the cladding layer can act as a sacrificial anode to form a thin and dense oxide and hydroxide layer on the surface of the aluminum alloy tube and effectively prevent further oxidation reactions to improve the corrosion resistance and reliability of the aluminum alloy tube and extend its service life.

[0021] Furthermore, the present invention also sets the laser power of the laser beam, the spot diameter, the passing speed of the aluminum alloy tube and the speed of conveying the cladding layer powder / alloy wire within a certain range, thereby accurately controlling the laser cladding process flow, so that the formed cladding layer has the advantages of small dilution, dense structure, good bonding with the aluminum alloy tube, and not easy to fall off. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0023] Figure 1 A process flow chart of laser cladding processing of corrosion-resistant aluminum alloy tubes provided by the present invention;

[0024] Figure 2 This is a schematic diagram of the processing principle of the aluminum alloy internal threaded pipe in the present invention;

[0025] Figure 3 This is a comparison chart of the performance test results of aluminum alloy internally threaded pipes under the process of the present invention and the traditional process;

[0026] Figure 4 This is a comparison chart of SWAAT test results of aluminum alloy internally threaded pipes under the process of the present invention and the traditional process. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams.

[0028] The present invention provides a process for laser cladding processing of corrosion-resistant aluminum alloy tubes. The laser cladding process is mainly added after the hot extrusion process, and the aluminum alloy tube is laser clad to form a zinc or zinc alloy cladding layer on the surface of the aluminum alloy tube, thereby improving the corrosion resistance and reliability of the aluminum alloy tube and extending the service life. At the same time, various parameters in the laser cladding process are accurately controlled so that the cladding layer has the advantages of small dilution, dense structure, good combination with the aluminum alloy tube, and not easy to fall off.

[0029] Combination Figure 1 , this process mainly includes:

[0030] First, the aluminum alloy billet is hot extruded to be formed into an aluminum alloy tube.

[0031] In the hot extrusion process, aluminum alloy round bars of specified grades are selected as aluminum alloy billets, and the aluminum alloy billets are gradient heated so that there is a temperature difference from the core to the surface of the aluminum alloy tube. This can effectively control the temperature distribution of the material during the extrusion process, improve the fluidity of the aluminum alloy tube, and facilitate forming.

[0032] At the same time, the aluminum alloy billet is gradient heated to 400∽450℃, and in winter when the temperature is lower, it is heated to 430∽470℃ to reduce the deformation resistance of the aluminum alloy billet and improve the plasticity, thereby reducing the extrusion force, making it easier for the aluminum alloy billet to fill the mold and improving production efficiency.

[0033] Furthermore, the heated aluminum alloy billet is extruded through a die, and the die specification of the aluminum alloy billet is adapted to the tonnage of the extrusion equipment and the selected extrusion ratio (ratio of the cross-sectional area of ​​the aluminum alloy billet to the aluminum alloy tube after forming).

[0034] Specifically, in order to ensure that the cladding layer of the formed aluminum alloy tube can be firmly bonded to the surface of the aluminum alloy tube in the subsequent laser cladding process, the hot extrusion process in this process has a stricter extrusion ratio than the traditional hot extrusion process. Preferably, the extrusion ratio is configured to be ≥150, so that the aluminum alloy billet undergoes greater deformation in the mold, which helps to refine the grains, so that the hot-extruded aluminum alloy tube is dense and defect-free, with a smooth surface, improved mechanical properties, and at the same time improves the processing effect of subsequent laser cladding.

[0035] Next, the high-temperature aluminum alloy tube extruded by the die is cooled in a water tank.

[0036] Next, the formed aluminum alloy tube is laser clad to form a cladding layer.

[0037] In the laser cladding process, the aluminum alloy tube is first laid out to preset the laser scanning trajectory to ensure the accuracy and repeatability of the laser cladding path. Through the pre-set lines, the laser beam can be guided to move along the predetermined scanning trajectory, thereby achieving cladding of specific areas on the surface of the aluminum alloy tube to improve the cladding quality and efficiency.

[0038] Furthermore, the aluminum alloy tube needs to be straightened to ensure that the aluminum alloy tube will not be deformed due to the thermal stress generated by the laser beam, so that the aluminum alloy tube maintains a stable geometric shape before and after laser cladding. At the same time, the outer surface of the aluminum alloy tube is cleaned, for example, oil, dust, oxides and other contaminants on the outer surface of the aluminum alloy tube are removed to ensure the purity of the cladding area and a suitable cladding environment, so that the aluminum alloy tube can form a good metallurgical bond with the cladding layer.

[0039] Next, the laser beam emitting device is evenly distributed around the aluminum alloy tube and the laser beam is emitted corresponding to the scanning track. The laser beam first melts the surface of the aluminum alloy tube to form a molten pool, and at the same time, the cladding layer powder / alloy wire formed by zinc or zinc alloy is transported to the molten pool area. The zinc or zinc alloy melts and diffuses in the molten pool to evenly cover the surface of the aluminum alloy tube, and then quickly solidifies together with the surface of the aluminum alloy tube to form a cladding layer combined with the aluminum alloy tube on the surface of the aluminum alloy tube, so that the cladding layer can protect the aluminum alloy tube.

[0040] Specifically, at high temperature, the laser beam can not only melt the cladding powder / alloy wire, but also cause tiny melting on the surface of the aluminum alloy tube, so that the cladding powder / alloy wire and the material on the surface of the aluminum alloy tube are fully mixed in the liquid state, and then quickly solidify to form a strong metallurgical bond, and the cladding powder / alloy wire is not easy to fall off.

[0041] At the same time, due to the extremely high energy density of the laser beam during the laser cladding process, the size and shape of the molten pool can be accurately controlled, so only a small amount of aluminum alloy tubes are involved in the melting, so that the proportion of aluminum alloy tubes replaced by cladding layer powder / alloy wire, that is, the dilution degree is small, which can maintain the original chemical composition and properties of the cladding layer and effectively protect the aluminum alloy tubes.

[0042] In order to ensure that laser cladding can form a cladding layer with low dilution, dense structure, good bonding with the aluminum alloy tube, and not easy to fall off, during the laser cladding process, the laser power of the laser beam is controlled to be 3000-3500W, so that the laser beam has a higher laser power to melt more cladding layer powder / alloy wire and increase the depth of the cladding layer, while not being too high to cause the surface temperature of the aluminum alloy tube to increase, increasing the risk of overburning and deformation.

[0043] At the same time, the spot diameter of the laser beam is configured to be 3-5 mm, so that the spot of the laser beam is kept within an appropriate range, the laser beam energy is concentrated, and it is beneficial to the melting of the cladding layer powder / alloy wire and the formation of the cladding layer.

[0044] Furthermore, the passing speed of the aluminum alloy tube is configured to be 200-250 m / min, so that the passing speed of the aluminum alloy tube is compatible with the melting speed of the cladding layer powder / alloy wire, thereby improving the uniformity of the cladding layer.

[0045] Furthermore, the speed of conveying the cladding powder / alloy wire is configured to be 40-60 g / min to ensure that the cladding powder / alloy wire is fully melted while avoiding overheating and the formation of pores.

[0046] Therefore, by controlling the laser power and spot diameter of the laser beam, the passing speed of the aluminum alloy tube and the speed of conveying the cladding powder / alloy wire, the laser beam, the aluminum alloy tube and the cladding powder / alloy wire cooperate with each other to form a uniform cladding layer on the surface of the aluminum alloy tube.

[0047] Furthermore, the cladding layer powder / alloy wire is formed of zinc or zinc alloy, so that a zinc cladding layer is formed on the surface of the aluminum alloy tube to protect the aluminum alloy tube. The zinc cladding layer on the surface is exposed to an electrolyte (such as seawater or humid air), and the zinc cladding layer will preferentially undergo an oxidation reaction to form a thin and dense oxide and hydroxide layer on the surface of the aluminum alloy tube, thereby protecting the aluminum alloy tube from corrosion to improve the corrosion resistance and reliability of the aluminum alloy tube. At the same time, the oxide and hydroxide layer can effectively prevent further oxidation reactions to increase the service life.

[0048] In this example, a synchronous powder feeding / wire feeding method is adopted. While emitting the laser beam, the cladding layer powder / alloy wire is synchronously transported to the area where the laser beam is located. This can improve the reasonable utilization rate of the cladding layer powder / alloy wire and has good controllability, thereby improving the quality of the cladding layer and the processing accuracy of the aluminum alloy tube.

[0049] Specifically, the cladding layer powder is transported through a conveying pipe parallel to the laser beam, and the conveying pipe is arranged at the rear of the laser beam nozzle close to the laser beam emitting device (behind the position where the laser beam contacts the aluminum alloy tube); and 1-2 bar nitrogen is continuously introduced into the conveying pipe, and the cladding layer powder is added to the conveying pipe through a funnel-shaped feeding device. Under the action of the nitrogen flow, the cladding layer powder is driven to continuously spray onto the surface of the aluminum alloy tube. At the same time, the conveying speed of the cladding layer powder can be accurately controlled by controlling the powder addition amount of the funnel-shaped feeding device and the flow rate of nitrogen.

[0050] Furthermore, the cladding alloy wire is clamped and conveyed by a group of rollers, and the rollers are arranged at the rear of the laser beam nozzle close to the laser beam emitting device (behind the position where the laser beam contacts the aluminum alloy tube); since the outer diameter of the cladding alloy wire is 1.2 mm or 1.6 mm, the conveying speed, conveying amount and conveying volume of the cladding alloy wire can be accurately controlled by controlling the rotation speed of the rollers.

[0051] Furthermore, in some embodiments, the laser beam emitting device is configured as two laser cladding guns evenly distributed around the aluminum alloy tube at an angle of 180° to improve the uniformity of the cladding layer and reduce thermal stress concentration, but more precise control is required to ensure that the energy distribution of the two laser beams can cooperate to avoid the occurrence of cladding defects.

[0052] In some embodiments, the laser beam emitting device can also be configured into three laser cladding guns evenly distributed around the aluminum alloy tube at an angle of 120°, so that the laser beam emitting device has higher flexibility and controllability, so that the three laser beams can cooperate to achieve more complex cladding paths and patterns, and can shape the laser beam into a circumferentially evenly distributed light spot, forming a more uniform cladding layer and better surface quality on the surface of the aluminum alloy tube.

[0053] During the laser cladding process, two or three laser cladding guns are fired synchronously, the laser cladding guns are fixed, and the aluminum alloy tube moves axially in a straight line, so that the laser beam and cladding layer powder / alloy wire act evenly on the surface of the aluminum alloy tube, forming a cladding layer on the entire surface of the aluminum alloy tube.

[0054] Finally, the aluminum alloy tube after laser cladding is cooled in a water tank to optimize the metallurgical bonding between the cladding layer and the aluminum alloy tube, improve the bonding strength, and at the same time improve the stability of the cladding layer to improve the corrosion resistance and fatigue resistance of the aluminum alloy tube. The aluminum alloy tube is then placed in a large material basket.

[0055] In the next step, the aluminum alloy tube after laser cladding is subjected to subsequent finishing processing.

[0056] Specifically, the aluminum alloy tube includes an aluminum alloy smooth tube. For the aluminum alloy smooth tube, the finishing process is configured to perform coiling, online annealing, finishing, heat treatment and packaging and warehousing on the aluminum alloy smooth tube.

[0057] Furthermore, the aluminum alloy tube also includes an aluminum alloy internally threaded tube. For the aluminum alloy internally threaded tube, the finishing process is configured to perform coiling, online annealing, internal thread forming, finishing, heat treatment and packaging and warehousing on the aluminum alloy internally threaded tube.

[0058] The following is a detailed description of the process flow of the finishing treatment.

[0059] In the coiling process, the aluminum alloy tube is first paid out and the moving path of the aluminum alloy tube is preset. The pay-out device can guide the aluminum alloy tube to move along the predetermined path to avoid deviation or entanglement of the aluminum alloy tube during processing, so as to ensure the straightness and flatness of the aluminum alloy tube.

[0060] Next, the aluminum alloy tube is stretched, and the aluminum alloy tube is plastically deformed by external force under the action of the tensile force, thereby reducing the cross-section and extending the length. During the stretching process, the number of stretching passes is adapted to the size of the aluminum alloy tube.

[0061] Specifically, in order to avoid cracking and breaking of the aluminum alloy tube during the coiling process, reduce the tightness of the connection between the aluminum alloy tube and the cladding layer, and cause the cladding layer to fall off, the coiling process of this process has a smaller elongation coefficient and total deformation rate than the traditional coiling process. Preferably, the elongation coefficient of each pass (the multiple of the increase in length of the aluminum alloy tube after one stretching or the ratio of the cross-sectional area before and after stretching) is configured to be 1.1∽1.8, and the total deformation rate of stretching is configured to be 35%∽85%. By setting the elongation coefficient and total deformation rate within a smaller range, the processing rate of each pass can be determined, the processing process can be optimized, and the cracking or breaking of the aluminum alloy tube caused by excessive processing can be avoided. The stability and safety of the stretching process are ensured, and at the same time, the aluminum alloy tube and the cladding layer have a good metallurgical bond.

[0062] After coil drawing, the aluminum alloy tube is annealed online.

[0063] Similarly, in the online annealing process, the aluminum alloy tube is first laid out, the moving path of the aluminum alloy tube is preset, and it is straightened and the outer surface is cleaned. The temperature of the aluminum alloy tube is rapidly raised to the temperature required by the specific application through the induction heating chamber, so that the aluminum alloy tube is recrystallized to generate new grains in this process, eliminating the stress accumulated in the aluminum alloy tube during the coiling process, softening the aluminum alloy tube, and preventing the aluminum alloy tube from deformation and cracking during use. Finally, the recrystallized aluminum alloy tube is cooled in a water tank.

[0064] Furthermore, during the high-temperature online annealing process, the zinc in the cladding layer will further diffuse into the aluminum alloy tube, promoting the bonding of the cladding layer and the aluminum alloy tube, so that the cladding layer can better protect the aluminum alloy tube and improve the corrosion resistance of the aluminum alloy tube.

[0065] For the aluminum alloy internal threaded tube, after completing the online annealing, the aluminum alloy tube is internally threaded.

[0066] Specifically, combined Figure 2 The aluminum alloy tube is first reduced in diameter under the extrusion of the outer die 1 and the floating core head 2, and then enters the spinning gear mechanism 3. The steel ball 4 in the spinning gear mechanism 3 rotates and rolls around the aluminum alloy tube under the drive of the high-speed motor, and presses the aluminum alloy tube into the tooth groove of the threaded core head 5 placed inside the aluminum alloy tube, thereby forming a continuous tooth shape with a certain spiral angle in the inner cavity of the aluminum alloy tube.

[0067] Here, the height, top angle and overall helix angle of the tooth profile can be adaptively adjusted through the threaded core head according to the specific application, and the speed of the high-speed motor is preferably 15,000∽50,000rpm to improve the tooth profile molding quality.

[0068] Furthermore, during the internal thread forming process of the aluminum alloy tube, the temperature of the local surface of the aluminum alloy tube will increase during the extrusion diameter reduction and internal thread forming of the aluminum alloy tube, so that the zinc in the cladding layer will diffuse into the aluminum alloy tube again, further improving the bonding tightness between the cladding layer and the aluminum alloy tube.

[0069] For the aluminum alloy plain tube after online annealing, or the aluminum alloy internally threaded tube after internal thread forming, the aluminum alloy tube is subjected to finishing treatment.

[0070] In the finishing process, the aluminum alloy tube is straightened, cleaned on the outer surface, and inspected online before being wound and cut into coils required for specific applications in a regular manner to reduce damage to the cladding layer of the aluminum alloy tube during transportation and storage and extend its service life.

[0071] Next, the aluminum alloy tube is heat treated.

[0072] During the heat treatment, the aluminum alloy tube is firstly coiled and placed in an annealing heating furnace for heat treatment to promote the diffusion process inside the aluminum alloy tube, thereby increasing the thickness of the cladding layer.

[0073] Specifically, during the laser cladding process, due to the rapid cooling rate, the cladding layer may have incomplete fusion or microscopic holes, which will limit the growth of the cladding layer. Through heat treatment, the diffusion between atoms can be reactivated under a lower stress state, which will promote the further fusion of the powder particles that are not fully fused, thereby increasing the overall thickness of the cladding layer.

[0074] Furthermore, heat treatment can also improve the mechanical properties of aluminum alloy tubes. For example, through solution treatment and aging treatment (such as T6 heat treatment), high-density nano-scale strengthening phases such as MgZn2 and Al2Mg3Zn3 can be precipitated in the aluminum alloy tube, and these strengthening phases can effectively improve the yield strength and hardness of the aluminum alloy tube. In addition, heat treatment can also reduce the residual stress in the cladding layer and the aluminum alloy tube, and transform the tensile stress into compressive stress, thereby improving the toughness and fatigue life of the aluminum alloy tube.

[0075] In order to effectively increase the overall thickness of the cladding layer and improve the mechanical properties of the aluminum alloy tube, the temperature of the annealing heating furnace is set to 450∽570℃, and the aluminum alloy tube is heat treated for 30∽90 minutes, so that the zinc in the cladding layer further diffuses into the aluminum alloy tube at high temperature, so that the thickness of the cladding layer on the surface of the aluminum alloy tube after heat treatment reaches 450∽800μm, which effectively protects the aluminum alloy tube and improves the corrosion resistance of the aluminum alloy tube. At the same time, the mechanical properties of the aluminum alloy tube reach the O state, so that the aluminum alloy tube achieves the best strength and toughness combination.

[0076] Here, by adjusting the temperature or holding time of the annealing heating furnace, the mechanical properties of the aluminum alloy tube can also be adjusted to meet the state requirements required for other specific applications.

[0077] Finally, the aluminum alloy tubes are packaged and stored for easy storage, and the cladding layer is not prone to failure.

[0078] Therefore, the laser cladding process for processing corrosion-resistant aluminum alloy tubes provided by the present invention processes the aluminum alloy tubes through multiple steps and accurately controls the specific implementation parameters of each step to form a stable and uniform cladding layer on the surface of the aluminum alloy tube, effectively protecting the aluminum alloy tube, improving the corrosion resistance and reliability of the aluminum alloy tube, and increasing the service life.

[0079] In order to specifically illustrate the technical effect of the present process, in this example, the laser cladding process for processing corrosion-resistant aluminum alloy tubes provided by the present invention and the traditional process are used to respectively process and form three types of aluminum alloy internal threaded tubes made of 3003 material, namely 7*0.50+0.18, 7*0.50+0.25, and 6.35*0.50+0.20.

[0080] For example, an aluminum alloy internal threaded pipe with a specification of 7*0.50+0.18 refers to an aluminum alloy internal threaded pipe with an outer diameter of 7 mm, a wall thickness of 0.50 mm, and a thread tooth height of 0.18 mm.

[0081] Furthermore, performance tests were conducted on the aluminum alloy internally threaded pipes formed by the present process and the traditional process to obtain the corresponding strengths of the aluminum alloy internally threaded pipes under different processes.

[0082] Combination Figure 3 , which shows the comparison of performance test results of aluminum alloy internally threaded pipes.

[0083] As can be seen from the figure, the average tensile strength of the aluminum alloy internally threaded tube formed by this process is 115.7MPa, the average yield strength is 72.3MPa, and the average elongation is 35.3%. Compared with the aluminum alloy internally threaded tube formed by the traditional process, the tensile strength of the aluminum alloy internally threaded tube formed by this process is increased by 5.2MPa, and the yield strength is increased by 6.2MPa. The higher tensile strength and yield strength can effectively improve the pressure resistance of the aluminum alloy internally threaded tube.

[0084] Furthermore, the aluminum alloy internally threaded pipes formed by this process and the traditional process were subjected to SWAAT test. The SWAAT test simulates a salt spray test containing gases such as ammonia, which can reflect the corrosion resistance of the aluminum alloy internally threaded pipe, so as to obtain the corresponding corrosion resistance and service life of the aluminum alloy internally threaded pipe under different processes.

[0085] Combination Figure 3 and Figure 4 , which shows the comparison of SWAAT test results of aluminum alloy internally threaded pipes.

[0086] As can be seen from the figure, the average failure days of the aluminum alloy internal threaded pipe formed by this process is 46.3 days, which is much higher than the average failure days of 7.3 days of the aluminum alloy internal threaded pipe formed by the traditional process, and is about 7 times that of the traditional process. This fully demonstrates that this process can effectively improve the corrosion resistance and reliability of aluminum alloy pipes and extend their service life.

[0087] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A process for laser cladding of corrosion-resistant aluminum alloy tubes, characterized in that: The process comprises: hot extruding the aluminum alloy billet to form an aluminum alloy tube; The formed aluminum alloy tube is laser clad. First, the aluminum alloy tube is laid out to preset the laser scanning trajectory, and the laser beam is straightened and cleaned. Then, the laser beam emitting device is evenly distributed around the aluminum alloy tube and the laser beam is emitted corresponding to the scanning trajectory. The cladding layer powder / alloy wire formed by zinc or zinc alloy is simultaneously transported to the area where the laser beam is located. The laser power of the laser beam is 3000-3500W, the spot diameter is 3-5mm, the passing speed of the aluminum alloy tube is 200-250m / min, and the speed of transporting the cladding layer powder / alloy wire is 40-60g / min. Then, the aluminum alloy tube after laser cladding is cooled through a water tank. The aluminum alloy tube after laser cladding is subjected to finishing treatment.

2. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 1 is characterized in that: The aluminum alloy tube comprises an aluminum alloy smooth tube, and the finishing process is configured to perform coil drawing, online annealing, finishing, heat treatment and packaging and warehousing on the aluminum alloy smooth tube.

3. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 1 is characterized in that: The aluminum alloy tube includes an aluminum alloy internally threaded tube, and the finishing process is configured to perform coiling, online annealing, internal thread forming, finishing, heat treatment and packaging and warehousing on the aluminum alloy internally threaded tube.

4. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 2 or 3, characterized in that: In the hot extrusion process, the aluminum alloy billet is gradient heated to 400∽450°C or 430∽470°C, and then extruded through a die with an extrusion ratio of ≥150. The extruded aluminum alloy tube is cooled in a water tank.

5. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 2 or 3, characterized in that: In the coiling process, when the aluminum alloy tube is stretched, the stretching passes are adapted to the size of the aluminum alloy tube, and the elongation coefficient of each pass is 1.1 to 1.8, and the total deformation rate of the stretching is configured to be 35% to 85%.

6. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 2 or 3, characterized in that: In the heat treatment process, the aluminum alloy tube is placed in an annealing heating furnace, the temperature of the annealing heating furnace is set to 450-570°C, and the temperature is kept for 30-90 minutes to heat treat the aluminum alloy tube.

7. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 1, characterized in that: The laser beam emitting device is configured with three laser cladding guns evenly distributed around the aluminum alloy tube at an angle of 120°.

8. The process for laser cladding of corrosion-resistant aluminum alloy tube according to claim 1, characterized in that: The laser beam emitting device is configured with two laser cladding guns evenly distributed around the aluminum alloy tube at an angle of 180 degrees.

Images