CN114160625B

CN114160625B - Pulse current assisted rapid bending forming method for magnesium alloy pipe

Info

Publication number: CN114160625B
Application number: CN202111504749.6A
Authority: CN
Inventors: 徐虹; 任思宇; 王玉鹏; 闫荣辉; 白明; 马品奎; 程秀明
Original assignee: Jilin University
Current assignee: Jilin University
Priority date: 2021-12-01
Filing date: 2021-12-01
Publication date: 2022-09-23
Anticipated expiration: 2041-12-01
Also published as: CN114160625A

Abstract

The invention provides a pulse current assisted magnesium alloy pipe rapid bending forming method which comprises the steps of bending a magnesium alloy pipe subjected to homogenization treatment, and introducing pulse current in the bending process. The die materials of the bending die, the supporting roller and the like which are contacted with the magnesium alloy pipe adopt high-strength insulating ceramic materials. Compared with the traditional magnesium alloy bending process, the pulse current assisted bending forming is beneficial to promoting dislocation movement and recrystallization in the magnesium alloy plastic deformation process, can improve the plastic forming performance of the high-strength light pipe, effectively avoids the problems of fracture and rebound of the magnesium alloy during room-temperature bending, and has high product size precision. Compared with the traditional low-plasticity alloy pipe hot bending process, the whole process flow is simple and quick, and the method has good industrial application prospect.

Description

Pulse current assisted rapid bending forming method for magnesium alloy pipe

Technical Field

The invention belongs to the technical field of alloy profile processing and forming, and particularly relates to a pulse current assisted rapid bending and forming method for a magnesium alloy pipe.

Background

As one of the most interesting materials for industrial light weight, the magnesium alloy has the advantages of high specific strength and specific stiffness, good vibration absorption and damping performance, easiness in recycling and the like, and has wide application prospects in the fields of military industry (army carrying tools, tactical backpacks), medical instruments (wheelchairs, folding chairs) and the like which need alloy light weight. However, magnesium alloy belongs to a novel material, and has poor forming performance at normal temperature, and when the problem of plastic forming is researched, data accumulated in a plurality of previous researches cannot be directly applied, so that the research on bending forming of magnesium alloy pipe fittings is of great significance.

The bending forming of the magnesium alloy pipe is typical plastic forming, and the bending mode of the pipe mostly adopts a hot bending process. The students of Ohio State university preliminarily studied the room temperature and heating bending property of the magnesium alloy pipe, and the results show that the magnesium alloy is easy to break when bending deformation is carried out at room temperature, the bending forming property is very poor, the bending property of the magnesium alloy pipe is obviously improved when the magnesium alloy pipe is heated to 150 plus 200 ℃, and the bending processing of the magnesium alloy pipe can be carried out by using two times of relative bending radius. At present, the commonly used pipe hot bending methods include flame heating bent pipes, medium frequency induction local heating bent pipes and in-furnace heating bent pipes. The flame heating has low heat efficiency, is only suitable for bending large-diameter thin-wall pipe fittings, and the magnesium alloy has active and flammable properties and cannot be heated by flame. Although the plasticity of the magnesium alloy is improved at high temperature, the forming at high temperature can increase the deformation complexity, and the over-high heating temperature is not beneficial to the bending forming of the magnesium alloy pipe, because the over-high temperature can cause local softening of the pipe and wall thickness reduction during the bending process, and the pipe wall is not uniformly thinned and distributed.

The bending experimental method selected by the invention is press bending, and the press bending is the best process method for bending and forming the circular tube. Press bending is one of the earliest methods for bending and forming pipes, and the forming method is to bend a pipe (plate or bar) into a formed part with a certain angle and a certain curvature according to the design requirement by using a die. The bending forming can bend a pipe with a straight line section and a bending die, and has the characteristics of low die cost, high flexibility degree, short production period and the like. During bending, the tube blank is supported by two supporting rolls, an arc surface bending die with a certain bending angle is placed in the middle of the tube blank, and thrust is applied to the tube blank to carry out pressurized bending, so that a bent tube with a certain curvature radius is obtained. The bending forming has strong adaptability to the shape curvature, and is one of the main forming methods of the grid high-rib integral wall plate at present. But after bending at room temperature, the rebound phenomenon is obvious during unloading, and the dimensional accuracy is low.

Therefore, in view of the defects and shortcomings of the prior art, the invention aims to provide a magnesium alloy pipe bending process which is rapid, efficient and good in formability. On the basis of preparing the high-precision magnesium alloy pipe forming part, the process cost is reduced, the process flow is shortened, and the method is an ideal alloy plastic processing mode with low cost, short flow and high performance.

Disclosure of Invention

The electric pulse treatment technology has the characteristics of short time, high efficiency and high energy. The invention provides a pulse current assisted rapid bending forming method for a magnesium alloy pipe, which comprises the following steps:

(1) homogenizing the magnesium alloy pipe, preserving the heat at 400-500 ℃ for 1-5h, and then quenching the magnesium alloy pipe with water at 25-50 ℃ to obtain the homogenized magnesium alloy pipe;

(2) fixing the magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, respectively connecting symmetrical positions at two ends of the pipe with a positive electrode and a negative electrode of a pulse power supply, introducing current, operating the bending press after the reading is stable, setting the bending radius to be 120mm, and setting the motion speed of the bending die to be 6-10 mm/s; the preset bending angle is 70-120.0 degrees, the voltage is 4-8.0V, the current intensity is 3.5-7.0KA, the pulse width is 300-500 mu s, the frequency is 5-20.0kHz, the deformation area temperature is 140-280 ℃, the rebound rate of the magnesium alloy pipe is 1-9 percent after the bending is finished, and the time required by the process flow is 5-20 s.

Further, the magnesium alloy is one of AZ61, AZ80 or AM 30.

Furthermore, the AZ61 is Mg-6.39Al-0.71Zn-0.32Mn, and the mass ratio is as follows: 6.39% of Al, 0.71% of Zn, 0.32% of Mn, less than 0.02% of impurity and the balance of Mg; the AZ80 magnesium alloy is Mg-8.40Al-0.57Zn-0.17Mn, and the mass ratio is as follows: 8.40 percent of Al, 0.57 percent of Zn, 0.17 percent of Mn, less than 0.02 percent of impurity and the balance of Mg; the AM30 magnesium alloy is Mg-3.46Al-0.60Mn-0.08Zn, and comprises the following components in percentage by mass: 3.46 percent of Al, 0.60 percent of Mn, 0.08 percent of Zn, less than 0.02 percent of impurity and the balance of Mg.

Further, the magnesium alloy pipe is subjected to homogenization treatment in the step (1), the temperature is kept at 400 ℃ for 1h, and then quenching treatment is carried out by using water at 30-40 ℃ to obtain the magnesium alloy pipe subjected to homogenization treatment.

Further, the supporting roller or the bending die in the step (1) is made of high-strength insulating ceramic materials.

Further, the moving speed of the bending die in the step (2) is 6-8 mm/s; the preset bending angle is 90-110.0 degrees, the current intensity is 4-6KA, the deformation region temperature is 170-200 ℃, and after bending is finished, the resilience rate of the magnesium alloy pipe is 1.91-6.63 percent.

Further, the time required by the process flow in the step (2) is 8-10 s.

Compared with the prior art, the invention has the advantages that:

1. the pulse current auxiliary pipe forming is that the electro-plastic effect of a metal material is utilized, and pulse current is applied in the pipe bending deformation process, so that the pipe is easier to generate plastic deformation, the plastic deformation resistance in the bending processing process is reduced, a material with poor plasticity or unsuitable for thermal radiation or thermal conduction heating can be processed and formed, and the thinning processing of the pipe is completed; compared with a single bending material, the magnesium alloy material processed by the pulse current auxiliary bending process has the structure and appearance of equiaxed crystals which are uniformly distributed, crystal grains are more refined, and the pulse current promotes dislocation motion and annihilation generated in the deformation process so as to improve the nucleation rate of recrystallization; compared with the traditional processing, the working efficiency is greatly improved, and the cost and the energy loss are reduced.

2. Compared with the prior art, when bending is carried out at the same angle, the rebound rate of the invention is far smaller than that of the prior art, and meanwhile, when the bending angle is larger than 90 degrees, the rebound rate can still keep a stable and almost unchanged trend along with the increase of the bending angle when the material is subjected to bending and pulse treatment by adopting the process, the rebound rate is reduced along with the increase of the bending angle, but the lowest rebound rate is still far higher than that of the invention, and the rebound rate can still keep a stable and unchanged trend after being obviously reduced is not seen in the prior art, so that: the good effect of the invention is realized by the cooperation of the pulse current and the pipe bending deformation process.

3. The recrystallization fraction of the inner side of the AZ61 alloy at the planned bending position after homogenization treatment is 94.3%, the recrystallization fraction of the inner side of the AZ61 alloy after independent bending treatment is 3.1%, and the recrystallization fraction of the inner side of the AZ61 alloy after bending treatment and pulse current combined treatment is 54.5%, so that the synergistic effect of bending and pulse current is beneficial to improving the formability of the alloy.

Drawings

Fig. 1 is a schematic view of a press bending apparatus of the present invention, which mainly comprises: 1-bending a die, 2-placing an alloy pipe, 3, 3 '-supporting rollers, 4-a temperature measuring instrument, 5, 5' -power connecting wires and 6-a low-voltage pulse power supply;

the bending die 1 is positioned at the upper part of the device, the alloy pipe placing area 2 is positioned between the bending die 1 and the supporting rollers 3 and 3 ', the supporting rollers 3 and 3' are respectively positioned at the symmetrical positions of the left side and the right side of the lower part of the alloy pipe placing area 2, in the bending process, the bending die 1 provides downward pressure for the alloy pipe at the alloy pipe placing area 2, and the two supporting rollers 3 perform bending processing of different angles through the cooperative action of the two supporting rollers 3 and the bending die 1 in a rotation angle mode; the thermodetector 4 monitors the electric pulse current and the temperature of the to-be-deformed area in the bending process in real time; a low-voltage pulse power supply 6 is connected with the symmetrical positions at the left side and the right side of the alloy pipe through power supply connecting wires 5 and 5', and then pulse current is applied to the alloy pipe;

FIG. 2 is a statistical chart of recrystallization fractions before and after bending the alloy pipe of the present invention;

in FIG. 2: a: and (2) carrying out homogenization treatment on the inner side of the planned bending part of the AZ61 magnesium alloy pipe, and then carrying out recrystallization fraction, B: the process of comparative example 1 is adopted to treat AZ61 magnesium alloy pipe and then the inner side recrystallization fraction of the bending part is C: and the inner side recrystallization fraction of the bending part after the AZ61 magnesium alloy pipe is processed by the process of example 2.

The following comparative example 1 and examples 1 to 8 used AZ61 magnesium alloy (Mg-6.39Al-0.71Zn-0.32Mn in mass ratio of Al 6.39%, Zn 0.71%, Mn 0.32%, impurity <0.02%, and balance Mg); example 9 used was AZ80 magnesium alloy (Mg-8.40Al-0.57Zn-0.17Mn, in mass ratio: 8.40% Al, 0.57% Zn, 0.17% Mn, less than 0.02% impurity and the balance Mg); example 10 used was an AM30 magnesium alloy (Mg-3.46Al-0.60Mn-0.08Zn, in mass ratio: 3.46% Al, 0.60% Mn, 0.08% Zn, less than 0.02% impurity and the balance Mg).

Detailed Description

Comparative example 1:

the room-temperature bending deformation process of the AZ61 magnesium alloy comprises the following steps:

(1) the method for carrying out homogenization treatment on the magnesium alloy pipe comprises the following steps: keeping the temperature at 400 ℃ for 1h, and then quenching with water at 30-40 ℃ to obtain a magnesium alloy pipe subjected to homogenization treatment;

(2) fixing the magnesium alloy pipe subjected to homogenization treatment obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, and starting a machine to perform press bending, wherein: the bending radius is 120mm, the moving speed of a bending die is 8mm/s, the preset bending angle is 110.0 degrees, the time required by the process is 12s, and the temperature of a deformation area is 20-30 ℃. After bending, the magnesium alloy pipe has obvious resilience, the bending angle of the pipe is 127.3 degrees, and the resilience rate of the pipe is 15.73 percent.

Example 1:

a pulse current assisted AZ61 magnesium alloy pipe rapid bending forming method comprises the following steps:

(1) carrying out homogenization treatment on the AZ61 magnesium alloy pipe, which comprises the following steps: keeping the temperature at 400 ℃ for 1h, and then quenching with water at 30-40 ℃ to obtain a magnesium alloy pipe subjected to homogenization treatment;

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roller and a bending die of a hydraulic pipe bender, connecting positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, and the moving speed of the bending die is 8 mm/s; the preset bend angle is 110.0 °. The voltage is 6.0V, the current intensity is 3.5KA, the pulse width is 400 mu s, the frequency is 10.0kHz, the temperature of a deformation area is 140-165 ℃, and the time required by the process is 10 s. After bending, the magnesium alloy pipe has low resilience, the bending angle of the pipe is 117.29 degrees, and the resilience rate of the pipe is 6.63 percent.

Example 2:

(1) the method for carrying out homogenization treatment on the magnesium alloy pipe comprises the following steps: keeping the temperature at 400 ℃ for 1h, and then quenching the mixture by using water at 30-40 ℃ to obtain a magnesium alloy pipe subjected to homogenization treatment;

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roller and a bending die of a hydraulic pipe bender, connecting positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, and the moving speed of a bending die is 8 mm/s; the preset bend angle is 110.0 °. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 170-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 112.39 degrees, and the springback rate of the pipe is 2.18 percent.

Example 3:

(1) carrying out homogenization treatment on the magnesium alloy pipe, comprising the following steps: keeping the temperature at 400 ℃ for 1h, and then quenching with water at 30-40 ℃ to obtain a magnesium alloy pipe subjected to homogenization treatment;

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, and the moving speed of a bending die is 8 mm/s; the preset bend angle is 110.0 °. The voltage is 6.0V, the current intensity is 4.4KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 225-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 112.4 degrees, and the springback rate of the pipe is 2.19 percent.

Example 4:

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roller and a bending die of a hydraulic pipe bender, connecting positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, and the moving speed of a bending die is 8 mm/s; the preset bend angle is 110.0 °. The voltage is 6.0V, the current intensity is 4.8KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 260-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 112.37 degrees, and the springback rate of the pipe is 2.16 percent.

According to the experimental results of the comparative example 1 and the examples 2 to 4, compared with the prior art, in the pipe bending process, the bending process and the pulse current act together, so that the rebound degree after unloading is effectively reduced, and the effect is obvious when the pulse current intensity is above 4.0KA by adjusting the pulse current parameters.

Example 5:

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, and the temperature of the deformation region is 170-. The bending radius is 120mm, the moving speed of the bending die is 6mm/s, the bending angle is set to be 110.0 degrees, and the time required by the process is 12 s. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 112.1 degrees, and the springback rate of the pipe is 1.91 percent.

Example 6:

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, and the temperature of the deformation region is 170-. The bending radius is 120mm, the moving speed of the bending die is 10mm/s, the bending angle is set to be 110 degrees, and the time required by the process is 10 s. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 113.09 degrees, and the springback rate of the pipe is 2.81 percent.

Example 7:

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, the moving speed of the bending die is 8mm/s, and the bending angle is set to be 100 degrees. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 170-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 102.16 degrees, and the springback rate of the pipe is 2.16 percent.

Example 8:

(2) and (2) fixing the AZ61 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, the moving speed of the bending die is 8mm/s, and the bending angle is set to be 90 degrees. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 170-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 91.95 degrees, and the springback rate of the pipe is 2.17 percent.

Example 9:

a pulse current assisted AZ80 magnesium alloy pipe rapid bending forming method comprises the following steps:

(1) the method for carrying out homogenization treatment on the magnesium alloy pipe comprises the following steps: keeping the temperature at 420 ℃ for 1h, and then quenching with water at 30-40 ℃ to obtain a magnesium alloy pipe subjected to homogenization treatment;

(2) and (2) fixing the AZ80 magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, connecting the positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating the bending machine after the reading is stable. The bending radius is 120mm, the moving speed of the bending die is 8mm/s, and the bending angle is set to be 90 degrees. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mu s, the frequency is 10.0kHz, the temperature of a deformation area is 170-200 ℃, and the time required by the process is 9 s. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 91.98 degrees, and the springback rate of the pipe is 2.20 percent.

Example 10:

a pulse current assisted AM30 magnesium alloy pipe rapid bending forming method comprises the following steps:

(2) fixing the AM30 magnesium alloy pipe obtained in the step (1) between a supporting roller and a bending die of a hydraulic pipe bender, connecting positive and negative poles of a pulse power supply at symmetrical positions at two ends of the pipe, introducing current, and operating a press bending machine after the reading is stable. The bending radius is 120mm, the moving speed of the bending die is 8mm/s, and the bending angle is set to be 90 degrees. The voltage is 6.0V, the current intensity is 4.0KA, the pulse width is 400 mus, the frequency is 10.0kHz, the temperature of the deformation area is 170-. After bending, the magnesium alloy pipe almost has no springback, the bending angle of the pipe is 91.97 degrees, and the springback rate of the pipe is 2.19 percent.

TABLE 1 COMPARATIVE EXAMPLE 1 Press-bending Processes and Material Properties relating to EXAMPLES 1-8

The prior art is as follows: the Master thesis "AZ 61 magnesium alloy pipe bending forming study" page 71, third section open column "(2) bending forming experimental conclusion: when the bending angle is not less than 30 degrees, the bending angle and the rebound angle of the bent pipe are approximately in a linear relationship, and the bending angle and the rebound rate are in an inverse proportion relationship, namely the rebound rate is in a descending trend along with the increase of the bending angle. "in combination with this paper, page 48, Table 4.1 rebound analysis Table

Data in The Tab.4.1 The springback analysis table reference Table are as follows

As can be seen from table 1: the magnesium alloy pipe processed by a single bending process has high resilience rate, and the formability of the material is obviously influenced; but with the auxiliary addition of the pulse current, the rebound rate showed a significant decrease trend, wherein the rebound rates at 90 °, 100 ° and 110 ° were 2.17%, 2.16% and 2.18%, respectively, from which it can be seen that: when the bending angle of the steel plate is 90 degrees or more, the rebound rate is almost not changed along with the increase of the bending angle, the steel plate shows a stable trend, and the influence on the formability of the material tends to be stable. The results of the 4.1AZ61 rebound analysis table of page 48 of the master paper "AZ 61 magnesium alloy tube bending forming study" in the prior art show that: the rebound resilience at 90 ℃ is 10.17%, the rebound resilience at 120 ℃ is 9.13%, and the rebound resilience at 180 ℃ is 8.76% at the minimum. Compared with the prior art, the resilience (2.17%) of 90 degrees of the invention is far less than the resilience (10.17%) of the prior art, the paper discloses that the resilience of 180 degrees is the minimum value in the bending process of 0-180 degrees and is 8.76%, and is also far greater than the resilience of 90 degrees, 100 degrees and 110 degrees of the invention, in addition, the change between the bending angle and the resilience disclosed by the paper does not present a stable trend, which is different from the invention, so that the invention can be seen: the press bending process and the pulse current have synergistic effect, and meanwhile, the rebound rate of the material is obviously reduced, and the rebound rate can be almost kept stable and unchanged when the bending angle is larger than 90 degrees, which is a technical effect not provided by the prior art.

In addition, the recrystallization fraction of the inside of the AZ61 alloy at the pseudo-press bending after the homogenization treatment of example 2 of the present invention was 94.3%, the recrystallization fraction of the inside after the bending treatment alone was 3.1%, and the recrystallization fraction of the inside after the bending treatment and the pulse current treatment together was 54.5%, whereby it was found that the synergistic effect of the bending treatment and the pulse current contributes to the improvement of the formability of the alloy.

Claims

1. A pulse current assisted magnesium alloy pipe rapid bending forming method is characterized by comprising the following steps:

(2) fixing the magnesium alloy pipe obtained in the step (1) between a supporting roll and a bending die of a hydraulic pipe bender, respectively connecting symmetrical positions at two ends of the pipe with a positive electrode and a negative electrode of a pulse power supply, introducing current, operating the bending press after the reading is stable, setting the bending radius to be 120mm, and setting the motion speed of the bending die to be 6-10 mm/s; the preset bending angle is 70-120.0 degrees, the voltage is 4-8.0V, the current intensity is 3.5-7.0KA, the pulse width is 300-20.0 kHz, the frequency is 5-20.0kHz, the deformation area temperature is 140-280 ℃, after the bending is finished, the rebound rate of the magnesium alloy pipe is 1-9 percent, and the time required by the process flow is 5-20 s.

2. The pulse current assisted magnesium alloy pipe rapid bending forming method according to claim 1, characterized in that: the magnesium alloy is AZ61, AZ80 or AM 30.

3. The pulse current assisted magnesium alloy pipe rapid bending forming method as claimed in claim 2, characterized in that: the AZ61 is Mg-6.39Al-0.71Zn-0.32Mn, and is prepared from the following components in percentage by mass: 6.39% of Al, 0.71% of Zn, 0.32% of Mn, less than 0.02% of impurity and the balance of Mg; the AZ80 magnesium alloy is Mg-8.40Al-0.57Zn-0.17Mn, and the mass ratio is as follows: 8.40 percent of Al, 0.57 percent of Zn, 0.17 percent of Mn, less than 0.02 percent of impurity and the balance of Mg; the AM30 magnesium alloy is Mg-3.46Al-0.60Mn-0.08Zn, and comprises the following components in percentage by mass: 3.46 percent of Al, 0.60 percent of Mn, 0.08 percent of Zn, less than 0.02 percent of impurity and the balance of Mg.

4. The pulse current assisted magnesium alloy pipe rapid bending forming method according to claim 1 or 2, characterized in that: homogenizing the magnesium alloy pipe in the step (1), preserving heat for 1h at 400 ℃, and then quenching with water at 30-40 ℃ to obtain the homogenized magnesium alloy pipe.

5. The pulse current assisted magnesium alloy pipe rapid bending forming method according to claim 4, characterized in that: the supporting roller or the bending die in the step (1) is made of high-strength insulating ceramic materials.

6. The pulse current assisted magnesium alloy pipe rapid bending forming method according to claim 4, characterized in that: the moving speed of the bending die in the step (2) is 6-8 mm/s; the preset bending angle is 90-110.0 degrees, the current intensity is 4-6KA, the deformation zone temperature is 170-200 ℃, and after the bending is finished, the rebound rate of the magnesium alloy pipe is 1.91-6.63 percent.

7. The pulse current assisted magnesium alloy pipe rapid bending forming method according to claim 4, characterized in that: the time required by the process flow in the step (2) is 8-10 s.