A kind of ultra-high strength aluminum alloy magnetron GMA additive and welding method

Abstract

The present invention provides an ultra-high strength aluminum alloy magnetron GMA material addition and welding method, the material addition and welding equipment used include a welding gun, a magnetic head with three excitation paths, an A-path excitation current loop, a B-path excitation current loop, and a dual-path output excitation power supply, the welding gun uses a double-pulse cladding current, and the double-pulse cladding current, the A-path excitation current, and the B-path excitation current are coupled and matched with each other during material addition. The present invention can improve the heat and mass transfer process of ultra-high strength aluminum alloy GMA material addition and welding, improve its forming accuracy, refine its grain size, and greatly improve the forming quality of components.

Description

Technical Field

[0001] The present invention mainly relates to the technical field related to additive and welding, and specifically to an ultra-high strength aluminum alloy magnetron GMA additive and welding method. Background Art

[0002] Geometric arc (GMA) additive manufacturing is an advanced digital manufacturing technology that uses electric arc as a heat source and gradually forms metal parts from wires, surfaces, and bodies according to a three-dimensional digital model under the control of a program through the addition of wires. It has the advantages of short cycle, low cost, and few part size restrictions.

[0003] In the prior art, the related technology of the publication number CN107855629A, entitled Pulse composite magnetic field assisted GMAW high-speed welding method and device, is based on full digital arc welding, using a controllable pulse composite magnetic field generation system combined with a welding gun, and improving the lateral spread and longitudinal flow of liquid metal in the high-speed welding molten pool from the perspective of periodically regulating the arc and the molten droplet motion trajectory, thereby achieving the goal of simultaneously suppressing the high-speed welding undercut and hump defects. However, it still has the following defects:

[0004] 1) Applicability limitations: The above-mentioned existing technologies are mainly aimed at general GMAW high-speed welding, and are not sufficiently applicable to GMA additive manufacturing of ultra-high-strength aluminum alloys. When processing ultra-high-strength aluminum alloys, due to their special alloy composition and performance requirements, the original technology is difficult to meet the requirements in terms of arc capacity density control and alloy element burnout.

[0005] 2) Limited process window: Limited by the performance of the welding power source and the database configuration, it is difficult to meet the complex requirements of ultra-high-strength aluminum alloy GMA additive and welding only by controlling the droplet transition or adjusting the welding machine parameters, resulting in a relatively narrow process window.

[0006] 3) The molten pool cannot flow forward and backward: In additive manufacturing, insufficient stirring of the molten pool will prevent the alloy elements from being evenly distributed, resulting in component segregation and reducing the mechanical properties of the material; it will make it difficult for the gas in the molten pool to escape, forming pores, weakening the strength and density of the material, and concentrating the stress around the pores when bearing, which may cause the failure of the structural parts; it will cause uneven temperature distribution in the molten pool, restrict the formation and growth of crystal nuclei, resulting in coarse and uneven grains, reducing the toughness and strength of the material, and making the parts prone to brittle fracture when impacted; it will cause the liquid metal to flow unevenly, resulting in irregular shape of the specimen. For complex-shaped specimens, uneven thickness or deformation of thin walls will occur, affecting the installation and performance of parts in high-precision scenarios; it will make the solidified surface of the liquid metal rough, and the surface roughness will increase after the accumulation of new metal liquid, which may require additional processing, and will also increase the friction coefficient and wear of the parts and affect corrosion resistance and dimensional accuracy; it will also affect the bonding between two adjacent layers, resulting in poor interlayer bonding, stratification when bearing loads, greatly reducing the mechanical properties of the specimen, and may cause sudden failure in the manufacturing of high-load structural parts. Summary of the invention

[0007] In order to solve the shortcomings of the current technology, the present invention combines the existing technology and starts from practical application to provide an ultra-high strength aluminum alloy magnetron GMA additive and welding method. The technology adopts a double-pulse cladding current coupled with a dual-path excitation current to apply a composite pulse magnetic field to the arc from the front of the substrate. By targetedly changing the arc motion behavior and regulating the horizontal and vertical flow state of the liquid metal in the molten pool, the ultra-high strength aluminum alloy GMA additive and welding heat and mass transfer process are improved, the grains are refined, and the forming quality is optimized.

[0008] The technical solution of the present invention is as follows:

[0009] An ultra-high strength aluminum alloy magnetron GMA additive and welding method, the additive and welding equipment used includes a welding gun, a magnetic head with three excitation paths, an A-path excitation current loop for providing an A-path excitation current, a B-path excitation current loop for providing a B-path excitation current, and a dual-path output excitation power supply. The welding gun uses a double-pulse deposition current, and the double-pulse deposition current, the A-path excitation current, and the B-path excitation current have the following matching relationship during additive and welding:

[0010] Assuming the unit time is t, the double-pulse welding current alternates between high and low periods, wherein the cycle duration of the high pulse welding current and the low pulse welding current are both 4t. In the high pulse welding current stage, the power-on time of the A-path excitation current and the B-path excitation current are both 1t, and the A-path excitation current and the B-path excitation current are not energized at the same time. In the low pulse welding current stage, the power-on time of the A-path excitation current and the B-path excitation current are both 1t, and the A-path excitation current and the B-path excitation current are not energized at the same time.

[0011] Furthermore, in the high pulse welding current cycle t1-t5 period, the matching relationship between the A-way excitation current and the B-way excitation current is as follows:

[0012] During the time period t1-t2, the excitation current of path A is in an active state, and the excitation current of path B is in an inactive state;

[0013] During the time period t2-t3, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state;

[0014] During the time period t3-t4, the excitation current of path A is in an inactive state, and the excitation current of path B is in an active state;

[0015] During the time period t4-t5, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state;

[0016] During the low pulse welding current cycle t5-t9 period, the matching relationship between the A-way excitation current and the B-way excitation current is as follows:

[0017] During the time period t5-t6, the excitation current of path A is in an active state, and the excitation current of path B is in an inactive state;

[0018] During the time period t6-t7, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state;

[0019] During the time period t7-t8, the excitation current of path A is in an inactive state, and the excitation current of path B is in an active state;

[0020] During the time period t8-t9, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state.

[0021] Furthermore, the double-pulse welding current is controlled by a double-pulse welding power supply, and the A-path excitation current and the B-path excitation current are controlled by a dual-path output excitation power supply.

[0022] Furthermore, the high pulse welding current of the double pulse welding current is 200-350A, the low pulse welding current is 100-280A, the A-path excitation current and the B-path excitation current are 1-15A, and the frequency is 1-120HZ.

[0023] Furthermore, the additive speed is controlled at 0.6-1.2 m / min.

[0024] Furthermore, an electrical signal acquisition system is set up to collect the parameters of double-pulse cladding current, A-path excitation current, and B-path excitation current during the additive process.

[0025] Beneficial effects of the present invention:

[0026] 1. Based on the existing technology, the present invention is specifically aimed at GMA additive manufacturing and welding of ultra-high strength aluminum alloys. By applying a composite pulse magnetic field to the arc from the front of the substrate, the arc movement behavior is specifically changed to better adapt to the characteristics of ultra-high strength aluminum alloys.

[0027] 2. The present invention breaks through the limitations of the welding power supply's own performance and process window. By establishing the intrinsic connection between "excitation parameters-GMA additive electrical parameters-arc molten pool behavior-thermal cycle characteristics-precipitation phase behavior-organization evolution", the optimal matching between the composite pulsed magnetic field parameters and the GMA additive and welding electrical parameters is achieved, providing a broader process space for ultra-high strength aluminum alloy GMA additive manufacturing and welding.

[0028] 3. The present invention adopts a double-pulse welding current, which presents a periodic alternation of high and low currents, and cooperates with the double excitation currents IA and IB in a specific excitation (T)-off (3T)-excitation (T) mode. At different stages, the arc is subjected to electromagnetic forces in different directions, so that the arc can swing back and forth and left and right periodically, which can better adapt to the characteristics of ultra-high-strength aluminum alloys. The metal flow behavior of the molten pool produced by the combination of this specific arc waveform and excitation current can produce turbulent flows that collide with each other inside the molten pool. The strong convection is perpendicular to the growth direction of the columnar grains, making the dendrite arms easily break and form new grains. On the other hand, the turbulent flows that collide with each other under the action of electromagnetic force drive the heat fluctuations inside the molten pool, thereby causing the newly formed columnar crystals to remelt in fragile locations and break the grains.

[0029] 4. The double-pulse welding current acts on the molten pool from the aspect of heat input, and its high-frequency pulse can generate precise heat pulses, which makes the local temperature of the molten pool rise in a short time. The dual-path excitation coupling waveform structure plays a role from the perspective of magnetic field control. The magnetic field will generate Lorentz force on the charged particles in the liquid metal. According to the Lorentz force formula (where is the particle charge, is the particle movement speed, and is the magnetic induction intensity), when there is current in the liquid metal (directional movement of charged particles), the liquid metal will be affected by force under the action of the magnetic field. In this local high-temperature area, the magnetic field guides the liquid metal to flow in the desired direction. The combination of the two can achieve fine control of the solidification process of the molten pool. When manufacturing high-precision metal parts, this fine control can make the grain structure of the molten pool after solidification finer and more uniform, avoiding coarse grains or local component segregation. This is because good temperature and flow control are conducive to the uniform formation and growth of crystal nuclei.

[0030] 5. The double-pulse deposition current can adjust the frequency and energy of the droplet transition. Its low-frequency pulse can make the droplet transition at a relatively stable frequency. The magnetic field generated by the dual-path excitation coupling waveform structure will generate magnetic force on the droplet. The droplet can be regarded as a charged body during the transition process. When it is in the magnetic field, according to the Ampere force formula (for a long straight wire, is the current, is the wire length, is the magnetic induction intensity. For the droplet, the force it receives can be analyzed by analogy), the magnetic field will change the force received by the droplet. This magnetic force accurately guides the droplet, allowing it to fall accurately into the appropriate position in the molten pool, avoiding splashing and deviation of the droplet, thereby significantly improving the forming quality of the deposited layer, making the deposited layer more beautiful and uniform in appearance, and the fish scale pattern more regular.

[0031] 6. Excitation waveform matching Dual pulse current can make the two play a role in different aspects, and cooperate with each other to achieve better additive and welding effects: dual pulse current mainly affects the molten pool and adjusts the droplet transition from the perspective of heat input, while the dual-path excitation coupling waveform structure mainly acts on the molten pool and droplets from the perspective of magnetic field control. Their combination can achieve more precise control in multiple key links, such as controlling the temperature distribution of the molten pool and the flow of liquid metal, achieving the coordination of droplet transition and weld formation, and enhancing the stability of the additive and welding process. This cooperation can give full play to their respective advantages and make up for the shortcomings of a single factor, thereby improving the quality and performance of additive and welded parts.

[0032] 7. The combination of double-pulse deposition current and dual-path excitation coupling waveform structure can improve the efficiency of additive and welding while ensuring the quality of additive and welding: the reasonable parameter setting of the double-pulse deposition current can accelerate the formation and solidification speed of the molten pool, and the magnetic field control of the dual-path excitation coupling waveform structure can reduce the unstable factors and defect repair time in the additive and welding process. In the automated additive and welding production line, this combination can appropriately increase the deposition speed and reduce the scrap rate at the same time, because the high-quality test piece forming reduces the workload of later quality inspection and rework. This comprehensive balance can better meet the dual requirements of industrial production for additive quality and efficiency and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the additive and welding equipment of the present invention.

[0034] Figure 2 It is a schematic diagram related to the composite pulse magnetic field generating structure of the present invention.

[0035] Figure 3 It is a schematic diagram of the double-pulse welding current and the dual-path excitation current waveforms of the present invention.

[0036] Figure 4 It is a schematic diagram of the external electromagnetic force and arc movement of the present invention.

[0037] Figure 5 This is the additive forming and grain orientation diagram of the ultra-high strength aluminum alloy GMA of the present invention.

[0038] Numbers shown in the accompanying drawings:

[0039] 1. First magnetic head; 2. Second magnetic head; 3. Third magnetic head; 4. A-way excitation current circuit; 5. B-way excitation current circuit; 6. Welding gun; 7. Excitation power supply; 8. Electrical signal acquisition system; 9. Double-pulse welding power supply. DETAILED DESCRIPTION

[0040] The present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the application.

[0041] Example 1 This example provides an ultra-high strength aluminum alloy magnetron GMA additive and welding method, which is mainly a new magnetic field-assisted ultra-high strength aluminum alloy GMA additive and welding process based on the new technology of matching pulse excitation current and double pulse welding current waveform.

[0042] This embodiment proposes to carry out research on ultra-high strength aluminum alloy GMA additive and welding with composite pulse magnetic field assisted pulse welding power source based on domestic high-performance welding power source. That is, the composite pulse magnetic field is applied to the arc from the front of the substrate, and the arc motion behavior is changed in a targeted manner, and the horizontal and vertical flow states of the molten pool liquid metal are regulated at the same time, thereby improving the ultra-high strength aluminum alloy GMA additive and welding heat and mass transfer process, improving its forming accuracy, refining its grain size, and greatly improving the forming quality of the component. In this process, the pulse magnetic field and the pulse welding current are coupled with each other; in theory, the composite pulse magnetic field assisted pulse welding power source ultra-high strength aluminum alloy GMA additive and welding forming mechanism are deeply studied, and the intrinsic connection between "excitation parameters-GMA additive electrical parameters-arc molten pool behavior-thermal cycle characteristics-precipitation phase behavior-organization evolution" is established, so as to achieve the optimal matching between composite pulse magnetic field parameters and GMA additive and welding electrical parameters. This has important academic significance and engineering practical value for enriching the theory of GMA additive and welding process and promoting the development of composite pulse magnetic field assisted ultra-high strength aluminum alloy GMA additive and welding process.

[0043] refer to Figure 1As shown, the additive and welding equipment used in the additive and welding method of this embodiment is related. The additive and welding equipment mainly includes a welding gun and a composite pulse magnetic field generating structure. The composite pulse magnetic field generating structure mainly includes a magnetic head with three excitation paths, namely the first magnetic head 1, the second magnetic head 2 and the third magnetic head 3 shown in the figure, and the material of the magnetic head is industrial pure iron. The device also includes a dual excitation current circuit, that is, an A-way excitation current circuit 4 for providing an A-way excitation current and a B-way excitation current circuit 5 for providing a B-way excitation current. The excitation coil is a copper wire, the circuit connection method is parallel, and the excitation current is provided by an excitation power supply 7 with dual output currents. The magnetic head is fixed on the welding gun 6, and an electrical signal acquisition system 8 is provided at the same time. The electrical signal acquisition system 8 is composed of a voltage sensor, a Hall current sensor and a NI data acquisition card. These components work together to accurately collect electrical signal data in the additive and welding process, wherein the electrical signal data is mainly the electrical signals of the two-way excitation current and the electrical signals of the dual-pulse cladding current. The double pulse current used by the welding gun 6 for material addition and welding is provided by a double pulse welding power source 9, which can provide periodic high and low pulse currents.

[0044] The specific methods for adding and welding ultra-high strength aluminum alloy GMA using the above-mentioned additive equipment are as follows:

[0045] 1) First, initialize the device and set the excitation current of channel A and channel B. The excitation current setting range is 1-15A and the excitation frequency is 1-120HZ.

[0046] 2) Set the parameters related to double pulse welding current and scanning speed. For double pulse welding current, the setting range of high pulse welding current is 200-350A, the setting range of low pulse welding current is 100-280A, the additive voltage is 20-35V, the scanning speed is 0.6-1.2m / min, and the shielding gas flow rate is 15-25L / min.

[0047] 3) Set the waveform matching relationship between the double-pulse welding current, A-path excitation current, and B-path excitation current.

[0048] refer to Figure 3 As shown, taking unit time t as the unit, the high and low pulses of the double-pulse welding current alternate periodically, and the single duration period of the high pulse welding current and the low pulse welding current are both 4t, that is, the high pulse current duration is in the time period t1-t2, t2-t3, t3-t4, t4-t5, and the low pulse current duration is in the time period t5-t6, t6-t7, t7-t8, t8-t9. The welding current shows a double current high and low periodic alternation.

[0049] For the excitation current, during the high pulse current duration period, the excitation time of the A-way excitation current and the B-way excitation current is 1t, and they are not excited during the remaining 3t, and the excitation current of A-way and the excitation current of B are excited alternately. During the low pulse current duration period, the excitation time of the A-way excitation current and the B-way excitation current is 1t, and they are not excited during the remaining 3t, and the excitation current of A-way and the excitation current of B are excited alternately.

[0050] Taking a double pulse cycle as an example, the coupling relationship between the double pulse welding current, the A-path excitation current, and the B-path excitation current is specifically described. In the following, the excitation path without the winding of the excitation coil is collectively referred to as the C-path. Figure 4 as shown).

[0051] In the peak phase of double pulse welding current, that is, the high pulse current phase (t1-t5):

[0052] In the t1-t2 stage, the excitation current of circuit A is in the excitation stage, and the excitation current of circuit B is in the non-activation stage. At this time, circuit A is N-level, circuit B is S-level, and circuit C is S-level. Since there is an inter-polar attractive magnetic field between circuit A and circuit C, and there is an inter-polar repulsive magnetic field between circuit B and circuit C, the arc deflects to the right front in the welding direction;

[0053] In the t2-t3 stage, the excitation current of path A is in the non-activated stage, and the excitation current of path B is in the non-activated stage. At this time, there is no magnetic field between the three paths. Under the action of the arc's own stiffness, the arc and the molten pool move backward to the wire axis without deflection.

[0054] In the t3-t4 stage, the excitation current of circuit B is in the activation stage, and the excitation current of circuit A is in the non-activation stage. At this time, circuit A is at level N, circuit B is at level S, and circuit C is at level N. Since there is a repulsive magnetic field between the same poles of circuit A and circuit C, and an attractive magnetic field between the opposite poles of circuit B and circuit C, the arc deflects to the left front of the welding direction;

[0055] In the t4-t5 stage, the excitation current of path A is in the non-activated stage, and the excitation current of path B is in the non-activated stage. At this time, there is no magnetic field between the three paths. Under the action of the arc's own stiffness, the arc and the molten pool move backward to the wire axis position without deflection.

[0056] In the above process, since the deposition current is in the high pulse stage, the heat input is high, and the arc and molten pool are large.

[0057] In the double pulse welding current base value stage, that is, the low pulse current stage (t5-t9):

[0058] In the t5-t6 stage, the excitation current of circuit A is in the activation stage, and the excitation current of circuit B is in the non-activation stage. At this time, circuit A is at N level, circuit B is at S level, and circuit C is at S level. Since there is an inter-polar attractive magnetic field between circuit A and circuit C, and an inter-polar repulsive magnetic field between circuit B and circuit C, the arc deflects to the right front in the welding direction;

[0059] In the t6-t7 stage, the excitation current of path A is in the non-activated stage, and the excitation current of path B is in the non-activated stage. At this time, there is no magnetic field between the three paths. Under the action of the arc's own stiffness, the arc and the molten pool move backward to the wire axis without deflection.

[0060] In the stage t7-t8, the excitation current of circuit B is in the activation stage, and the excitation current of circuit A is in the non-activation stage. At this time, circuit A is at level N, circuit B is at level S, and circuit C is at level N. Since there is a repulsive magnetic field between the same poles of circuit A and circuit C, and an attractive magnetic field between the opposite poles of circuit B and circuit C, the arc deflects to the left front in the welding direction;

[0061] In the t8-t9 stage, the excitation current of path A is in the non-activated stage, and the excitation current of path B is in the non-activated stage. At this time, there is no magnetic field between the three paths. Under the action of the arc's own stiffness, the arc and the molten pool move backward to the wire axis position without deflection.

[0062] Since the deposition current is in the low pulse stage, the heat input is high and the arc and weld pool are small.

[0063] Based on the above current matching relationship, the following can be generated periodically in the arc during the additive process: Figure 4 The electromagnetic forces shown are:

[0064] In the t1-t2 stage, the pulsed cladding current peak (high pulse) coupled with the A-path excitation current is in the activation stage, the arc and the molten pool are large, and the A-path excitation current is in the activation stage. Under the action of the exciting magnetic field, the forward-leaning and right-moving arc pushes the molten pool metal to flow to the right front in the direction of additive material;

[0065] In the t2-t3 stage, the pulse welding current peak (high pulse) coupled with the dual excitation current is in the non-activated stage, the arc and the molten pool are large, the two excitation currents are in the non-activated stage, the external electromagnetic force disappears, and the pulse arc's own stiffness pushes the molten pool metal to flow from the deviated position to the wire axis position;

[0066] In the t3-t4 stage, the pulse cladding current peak (high pulse) coupled with the B-path excitation current is in the activation stage, the arc and the molten pool are large, and the B-path excitation current is in the activation stage. Under the action of the exciting magnetic field, the forward-leaning and left-moving arc pushes the molten pool metal to flow to the left front in the additive direction again;

[0067] In the t4-t5 stage, the pulsed cladding current peak (high pulse) coupled with the dual excitation current is in the non-activated stage, the arc and the molten pool are large, the two excitation currents are in the non-activated stage, the external electromagnetic force disappears, and the pulsed arc's own stiffness pushes the molten pool metal from the deviated position to the wire axis position;

[0068] In the t5-t6 stage, the pulsed deposition current base value (low pulse) coupled with the A-path excitation current is in the activation stage, the arc and the molten pool are small, and the A-path excitation current is in the activation stage. Under the action of the exciting magnetic field, the forward-leaning and right-moving arc pushes the molten pool metal to flow to the right front in the direction of material addition;

[0069] In the t6-t7 stage, the pulsed cladding current base value (low pulse) coupled with the dual excitation current is in the non-activated stage, the arc and the molten pool are small, the two excitation currents are in the non-activated stage, the external electromagnetic force disappears, and the pulsed arc's own stiffness pushes the molten pool metal to flow from the deviated position to the wire axis position;

[0070] In the stage t7-t8, the pulsed cladding current base value (low pulse) coupled with the B-path excitation current is in the activation stage, the arc and the molten pool are small, and the B-path excitation current is in the activation stage. Under the action of the excited magnetic field, the forward-leaning and left-moving arc pushes the molten pool metal to flow to the left front in the additive direction again;

[0071] In the t8-t9 stage, the pulse welding current base value (low pulse) coupled with the dual excitation current is in the non-activated stage, the arc and the molten pool are small, the two excitation paths are in the non-activated stage, and the external electromagnetic force disappears. Under the action of the pulse arc's own stiffness, the molten pool metal is pushed from the deviated position to the wire axis position.

[0072] 4) After setting the waveform matching relationship between the dual-pulse additive circuit and the dual-path excitation current, the A and B excitation currents and the high and low dual-pulse deposition currents are coupled with each other during the additive and welding process and remain stable, starting stable magnetic field-assisted additive manufacturing and welding.

[0073] Through the above cycle process, under the alternating action of dual-path excitation current and high and low pulse current, the arc and droplets swing forward and left and right periodically. At the same time, the arc volume, arc swing amplitude and droplet swing amplitude all change periodically, realizing the forward and backward and left and right flow of the molten pool metal, improving the heat and mass transfer behavior of the molten pool, and improving the forming accuracy.

[0074] The coupling of dual-path excitation current and dual-pulse welding current promotes the flow behavior of the molten pool metal, resulting in turbulent flows that collide with each other inside the molten pool. In this process, the strong convection of the molten pool is perpendicular to the growth direction of the columnar grains. As a result, the dendrite arms are easily broken by the shear force of the strong fluid flow, thus forming new grains and playing a role in grain refinement. On the other hand, the turbulent flows of the molten pool that collide with each other under the action of electromagnetic force drive the heat fluctuation inside the molten pool, thereby remelting the newly formed columnar crystals at the fragile parts and breaking the grains.

[0075] The arc is periodically swung by coupling the double-pulse deposition current and the double-circuit excitation current. Due to the dragging phenomenon of the arc shape, the heat dissipation area of ​​the liquid molten metal is increased, reducing the heat input. For ultra-high-strength aluminum alloys, the evaporation behavior of beneficial elements such as Zn and Mg is suppressed. In the process of additive and welding, high and low pulse currents act alternately. In the high pulse current stage, the current intensity is large, which will generate a large electromagnetic force. This electromagnetic force can drive the liquid metal in the molten pool to move violently, playing the role of stirring the molten pool. This stirring action helps to refine the grains after the molten pool solidifies. Because the uniform distribution of components in the molten pool during the solidification process is conducive to the formation of more crystal nuclei and prevents the growth of grains. In aluminum alloy additive, the stirring of high and low pulse currents can make the alloy elements in the aluminum alloy molten pool more evenly distributed, and a finer grain structure can be obtained after solidification, thereby improving the strength and toughness of the additive joint. The low pulse current stage can alleviate the violent movement of the molten pool to a certain extent. The high and low pulse currents cooperate with each other to change the fluidity of the molten pool within a suitable range. High pulse current increases fluidity, allowing the molten pool to better fill the weld gap; low pulse current can prevent excessive flow of molten pool metal and ensure the stability of the molten pool shape. High pulse current will cause the temperature of the molten pool to rise rapidly, while the temperature rise rate of the molten pool will slow down during the low pulse current stage. This alternating change helps control the heat input of the molten pool.

[0076] When adjusting the matching relationship between the double-pulse welding current and the dual-path excitation current, it can be observed from several aspects:

[0077] 1. Influence on heat and mass transfer in molten pool

[0078] The double-pulse deposition current mainly affects the molten pool from the perspective of heat input. The high and low pulse settings must ensure that the molten pool has appropriate heat input to avoid overheating or overcooling. If the heat input is too high, the molten pool temperature may be too high, the alloy element burnout may be aggravated, the droplet transition may be too fast and unstable, and the liquid metal flow in the molten pool may be too violent, affecting the solidification process of the molten pool and the final microstructure. If the heat input is too low, the metal wire is not fully melted, the molten pool cannot be formed normally, or the formed molten pool is too small, affecting the efficiency and quality of additive manufacturing and welding.

[0079] When adjusting the matching relationship, the influence of the magnetic field generated by the dual excitation current on the flow of liquid metal in the molten pool should be considered. The magnetic field will change the flow direction and speed of the liquid metal, which may accelerate or slow down the heat and mass transfer process in the molten pool. For example, when the direction of liquid metal flow guided by the magnetic field is inconsistent with the heat transfer direction, it may hinder the heat transfer in the molten pool, resulting in uneven local temperature and affecting the solidification quality of the molten pool.

[0080] The appropriate matching relationship between the double-pulse deposition current and the dual-circuit excitation current should be able to produce an appropriate stirring effect in the molten pool. Insufficient stirring of the molten pool will cause the alloy elements to be unevenly distributed, resulting in component segregation and reduced mechanical properties of the material; it will make it difficult for the gas in the molten pool to escape, forming pores and weakening the strength and density of the material. Excessive stirring may cause the liquid metal flow in the molten pool to be too chaotic, affecting the stability of the molten pool and the solidification process. Therefore, when adjusting the matching relationship, it is necessary to find the current matching method that can achieve the best stirring effect of the molten pool through experiments and simulations.

[0081] 2. Influence on droplet transition

[0082] The double-pulse deposition current can adjust the frequency and energy of the droplet transition, and its low-frequency pulse can make the droplet transition at a more stable frequency. When adjusting the matching relationship, it is necessary to ensure that the magnetic field generated by the dual-channel excitation current does not interfere with the frequency and energy of the droplet transition. If the magnetic field exerts too much force on the droplet, it may change the frequency of the droplet transition, making it too fast or too slow, affecting the filling process of the molten pool and the quality of the weld formation. At the same time, the magnetic field may also change the energy of the droplet, causing it to lose too much energy or gain extra energy during the transition process, causing the droplet to splash or fail to accurately fall into the appropriate position in the molten pool.

[0083] The energy stability of the arc is crucial to the formation and solidification process of the molten pool. The matching relationship between the double-pulse welding current and the dual-circuit excitation current should ensure the stable input of the arc energy. If the matching relationship is not appropriate, the arc energy may fluctuate greatly, affecting the temperature stability of the molten pool. When the pulse frequency of the double-pulse welding current does not match the power-on frequency of the dual-circuit excitation current, the arc energy may be too high or too low at certain times, causing the molten pool temperature to fluctuate, affecting the solidification process of the molten pool and the final microstructure.

[0084] 4. Impact on the quality of the final component

[0085] The microstructure and mechanical properties of the final component depend on the solidification process and microstructure of the molten pool. When adjusting the matching relationship between the double-pulse cladding current and the dual-path excitation current, its influence on the solidification process of the molten pool should be considered to ensure that the final component has good microstructure and mechanical properties.

[0086] The appropriate current matching relationship also has an important influence on the dimensional accuracy and surface quality of the component. If the liquid metal flow in the molten pool is unstable, it may lead to low dimensional accuracy of the component, uneven thin wall thickness or deformation. At the same time, if the droplet transition is unstable, it may lead to poor surface quality of the component, increased surface roughness, irregular fish scales and other problems. Therefore, when adjusting the matching relationship, it is necessary to improve the dimensional accuracy and surface quality of the component by optimizing the current matching relationship.

[0087] As a preferred solution of this embodiment, the additive and welding related parameters are collected in real time by the electrical signal acquisition system during the additive and welding process, so as to facilitate the analysis of molding quality, optimization parameters, fault diagnosis and the research of additive and welding process. By analyzing the monitored voltage and current signals, it can be judged whether the additive and welding process is stable and whether the additive and welding quality meets the requirements. Abnormal voltage or current fluctuations may indicate problems in the additive and welding process, such as arc instability, uneven additive and welding materials, etc. According to the analysis results of the monitoring signal, the additive and welding parameters can be adjusted and optimized. Adjust the parameters such as the deposition current, voltage, scanning speed, etc. to improve the additive and welding quality and efficiency. The monitoring signal can be used for fault diagnosis of additive and welding equipment. If the monitored electrical signal is abnormal, the equipment failure can be discovered in time, and corresponding maintenance measures can be taken to avoid production interruption. The monitoring signal can provide data support for the research of additive and welding process. By analyzing the electrical signals under different additive and welding conditions, the mechanism and law of the additive and welding process can be deeply understood, providing a theoretical basis for the development of additive and welding technology.

[0088] Example 2 The applicant has developed an external composite pulse magnetic field assisted ultra-high strength aluminum alloy GMA high-efficiency additive and welding system in Example 1. The composite pulse magnetic field interacts with the arc, and the dendrite arms are subjected to the shear force of the strong fluid flow, which is easy to break, thereby forming new grains and playing a role in refining the grains; on the other hand, the turbulence of the molten pool colliding with each other under the action of electromagnetic force drives the heat fluctuation inside the molten pool, so that the newly formed columnar crystals are remelted at the fragile parts and the grains are broken. Figure 5 As shown in Figure 5 The left side is a conventional additive method, and the right side is an additive method using the method proposed in this embodiment. Under the conditions of a wire feeding speed of 7 m / min and a scanning speed of 0.7 m / min, the structure is significantly refined, and the grain size is reduced from 49.88 μm to 38.87 μm.

Claims

1. An ultra-high strength aluminum alloy magnetron GMA additive and welding method, the additive and welding equipment used includes a welding gun, a magnetic head with three excitation paths, an A-path excitation current loop for providing an A-path excitation current, a B-path excitation current loop for providing a B-path excitation current, and a dual-path output excitation power supply, characterized in that: The welding gun adopts a double-pulse deposition current, and the matching relationship of the double-pulse deposition current, the A-path excitation current, and the B-path excitation current during material addition is as follows: Assuming the unit time is t, the double-pulse welding current alternates between high and low periods, wherein the cycle duration of the high pulse welding current and the low pulse welding current are both 4t. In the high pulse welding current stage, the power-on time of the A-path excitation current and the B-path excitation current are both 1t, and the A-path excitation current and the B-path excitation current are not energized at the same time. In the low pulse welding current stage, the power-on time of the A-path excitation current and the B-path excitation current are both 1t, and the A-path excitation current and the B-path excitation current are not energized at the same time.

2. The ultra-high strength aluminum alloy magnetron GMA material addition and welding method according to claim 1, characterized in that: During the high pulse welding current cycle t1-t5 period, the matching relationship between the A-way excitation current and the B-way excitation current is as follows: During the time period t1-t2, the excitation current of path A is in an active state, and the excitation current of path B is in an inactive state; During the time period t2-t3, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state; During the time period t3-t4, the excitation current of path A is in an inactive state, and the excitation current of path B is in an active state; During the time period t4-t5, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state; During the low pulse welding current cycle t5-t9 period, the matching relationship between the A-way excitation current and the B-way excitation current is as follows: During the time period t5-t6, the excitation current of path A is in an active state, and the excitation current of path B is in an inactive state; During the time period t6-t7, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state; During the time period t7-t8, the excitation current of path A is in an inactive state, and the excitation current of path B is in an active state; During the time period t8-t9, the excitation current of path A is in an inactive state, and the excitation current of path B is in an inactive state.

3. The ultra-high strength aluminum alloy magnetron GMA material addition and welding method according to claim 1, characterized in that: The double-pulse welding current is controlled by a double-pulse welding power supply, and the A-way excitation current and the B-way excitation current are controlled by a dual-way output excitation power supply.

4. The ultra-high strength aluminum alloy magnetron GMA material addition and welding method according to claim 1, characterized in that: The high pulse welding current of the double pulse welding current is 200-350A, the low pulse welding current is 100-280A, the A-way excitation current and the B-way excitation current are 1-15A, and the frequency is 1-120HZ.

5. The ultra-high strength aluminum alloy magnetron GMA material addition and welding method according to claim 1, characterized in that: The additive speed is controlled at 0.6-1.2m / min.

6. The ultra-high strength aluminum alloy magnetron GMA material addition and welding method according to claim 1, characterized in that: An electrical signal acquisition system is set up to collect the parameters of double-pulse deposition current, A-path excitation current, and B-path excitation current during the additive and welding process.

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