Method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating

Abstract

The invention discloses a method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating. The method comprises the following steps: step 1, surface treatment; step 2, rolling; step 3, straightening; and 4, short-time high-frequency electromagnetic induction heating is conducted, and the high-strength and high-plasticity AZ31B magnesium plate is obtained. Rolling is matched with short-time high-frequency electromagnetic induction heating, the grain size is reduced, the strength of the magnesium alloy is improved, the magnesium alloy generates high-density induction current so that top-speed heating can be carried out, the dynamic recrystallization temperature of the magnesium alloy under the current effect is obviously reduced, crystal lattices of the magnesium alloy are seriously distorted due to the fact that the magnesium alloy is affected by electronic wind, and the magnesium alloy has a good mechanical property. The high-strength and high-plasticity AZ31B magnesium plate has the advantages that the high-strength and high-plasticity AZ31B magnesium plate is uniform in dislocation density distribution, the average grain size is reduced, electron wind power generated by current can enable atom bonding to be broken, lattice atoms are rearranged, and the strength and plasticity of the magnesium alloy are improved by the specific structure, so that the high-strength and high-plasticity AZ31B magnesium plate is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of metal deformation and heat treatment processing, and specifically relates to a method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating. Background Art

[0002] The microstructure of a material greatly affects its mechanical properties, so obtaining a high-performance microstructure is the goal pursued by researchers. As the lightest structural material, magnesium alloy has the advantages of low density, high specific strength and specific stiffness, making it a focus of attention in the automotive, aerospace and other fields. However, due to its poor plasticity and low strength, the development and utilization of magnesium alloys is still limited. Therefore, one of the key challenges in developing advanced lightweight magnesium alloys is to achieve both low-temperature ductility and higher strength at the same time.

[0003] Traditionally, deformed magnesium alloys are usually processed by hot deformation or warm and cold deformation plus repeated intermediate annealing, which inevitably leads to high processing costs and low efficiency. Many researchers have studied various heat treatment methods to obtain microstructures with better mechanical properties. However, traditional heat treatment using a furnace is very time-consuming and requires heating at a certain temperature. This may cause problems such as oxidation, surface degradation, and grain growth, which hinder the performance of the material. Therefore, an effective method is needed to control the microstructure to ensure good material properties.

[0004] Recently, electrical pulse processing (EPT) has been developed to assist in the forming or heat treatment of various materials. Introducing an electric current into the deformed workpiece can effectively improve the deformability of different metals and alloys in terms of reducing flow stress, increasing elongation, and suppressing springback. This method has been widely used for various high strength-to-weight ratio alloys, such as titanium alloys and aluminum alloys. Several mechanisms have been reported for the effect of electrical pulses on microstructure, such as Joule heating and electron wind.

[0005] Therefore, it is necessary to develop a new process for industrial production of high-performance magnesium alloys with low cost and high efficiency. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating in view of the deficiencies of the above-mentioned prior art. The method reduces the grain size of the clean magnesium alloy billet by rolling to improve the strength of the magnesium alloy, and then cooperates with short-time high-frequency electromagnetic induction heating to make the straightened magnesium alloy billet generate a high-density induced current for extremely rapid heating, wherein the dynamic recrystallization temperature of the magnesium alloy billet under the action of the current is significantly reduced, and the magnesium alloy is severely distorted due to the influence of the electron wind, the dislocation density distribution becomes uniform, and the average grain size is reduced. The electron wind force generated by the current can break the atomic bonds and rearrange the lattice atoms. This unique structure improves the strength and plasticity of the magnesium alloy, thereby obtaining a high-strength and high-plasticity AZ31B magnesium plate.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating, characterized in that the method comprises the following steps:

[0008] Step 1: Surface treatment: grinding, cleaning and drying the AZ31B magnesium alloy blank in sequence to obtain a clean magnesium alloy blank;

[0009] Step 2, rolling: the clean magnesium alloy billet obtained in step 1 is subjected to multiple rolling processes to obtain a rolled magnesium alloy billet;

[0010] Step 3, straightening: straightening the rolled magnesium alloy billet obtained in step 2 to obtain a straightened magnesium alloy billet;

[0011] Step 4: short-time high-frequency electromagnetic induction heating: the straightened magnesium alloy billet obtained in step 3 is subjected to short-time high-frequency electromagnetic induction heating to obtain a high-strength and high-plasticity AZ31B magnesium plate.

[0012] The present invention removes oxides and impurities on the surface of AZ31B magnesium alloy billet by grinding to ensure the surface is smooth and flat, and at the same time makes the AZ31B magnesium alloy billet meet the thickness requirements, removes surface impurities by cleaning and drying to ensure the uniformity of surface quality after rolling processing, reduces the grain size of the clean magnesium alloy billet by rolling, improves the strength of the magnesium alloy, and performs deformation treatment on the clean magnesium alloy billet, accumulates participating stress and dislocation entanglement and plugging, so that the subsequent electromagnetic induction heating has a more significant effect on the deformed workpiece, and the rolled magnesium alloy billet is kept flat by straightening because the distance from the rolled magnesium alloy billet to the coil has a very obvious effect on the induction heating. In order to minimize the variables, the plate needs to be cold straightened to ensure the subsequent short-time high-frequency electromagnetic induction heating. Uniformity: If the rolled magnesium alloy billet is very flat after rolling, this step can be omitted. Through short-time high-frequency electromagnetic induction heating, the straightened magnesium alloy billet generates a high-density induced current for extremely rapid heating. The dynamic recrystallization temperature of the magnesium alloy billet under the action of current is significantly reduced. This depends on the non-thermal effect of the current during the deformation process. The magnesium alloy is affected by the electron wind, and the lattice is severely distorted. With the increase of electromagnetic induction heating time, the dislocation density distribution becomes uniform, and the microstructure of the magnesium alloy is affected by the current and magnetic field. The average grain size is reduced, and the electron wind force generated by the current can break the atomic bonds and rearrange the lattice atoms. This unique structure improves the strength and plasticity of the magnesium alloy, thereby obtaining a high-strength and high-plasticity AZ31B magnesium plate.

[0013] The above-mentioned method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the AZ31B magnesium alloy billet in step one is composed of the following components by mass fraction: Al 2.5% to 3.5%, Zn 0.6% to 1.4%, Mn 0.2% to 1.0%, Si 0.08%, Ca 0.04%, Fe0.003%, Cu 0.01%, and the balance is Mg and unavoidable impurities.

[0014] The above-mentioned method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the thickness of the AZ31B magnesium alloy blank in step 1 is 10mm to 13mm. The present invention controls the thickness of the AZ31B magnesium alloy blank to facilitate subsequent processing, and at the same time enables the magnesium alloy blank to have the best short-time high-frequency electromagnetic induction heating effect, thereby obtaining a high-strength and high-plasticity AZ31B magnesium plate of suitable thickness.

[0015] The above-mentioned method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the temperature of the multiple rolling in step 2 is 300°C to 400°C, the rolling speed is 9m / min to 11m / min, the pressing amount per pass is 8% to 12%, the total pressing amount of the multiple rolling is 45% to 55%, the time of returning to the furnace and keeping warm after the first rolling is 18min to 20min, and the time of returning to the furnace and keeping warm after the second rolling and subsequent rolling is 8min to 10min. The present invention controls the rolling parameters to make the microstructure of the rolled magnesium alloy billet uniform, which is more conducive to providing stable raw materials for subsequent short-time high-frequency electromagnetic induction heating, and ensures that the obtained rolled magnesium alloy billet has no edge cracks, no surface damage or other damage, etc., to ensure the integrity of the sample.

[0016] The above-mentioned method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the thickness of the multi-pass rolled magnesium alloy billet in step 2 is 5.5mm to 7.0mm. The present invention controls the thickness of the rolled magnesium alloy billet to facilitate the short-time high-frequency electromagnetic induction heating to have the best effect, and obtains a high-strength and high-plasticity AZ31B magnesium plate of appropriate thickness.

[0017] The above-mentioned method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the straightening described in step 3 is cold straightening. The present invention adopts cold straightening to prevent the microstructure from changing under high temperature conditions, which directly affects the subsequent electromagnetic induction heating results. In addition, the bending degree of the rolled magnesium alloy billet after rolling is small, high temperature is not required, and it can be carried out at low temperature, and the operation is simple.

[0018] The above-mentioned method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the frequency of the short-time high-frequency electromagnetic induction heating in step 4 is 300kHz~400kHz, the temperature is 150℃~200℃, and the time is 3s~20s. In the present invention, straightening the magnesium alloy billet under high-frequency electromagnetic induction heating will generate higher current density and magnetic field intensity. By controlling the heating frequency, that is, controlling the induced current generated by the straightening magnesium alloy billet, the Joule heat of the current on the straightening magnesium alloy billet can be controlled, and the microstructure of the magnesium alloy can be changed in a short time, so that the average grain size of the magnesium alloy is reduced, and the organizational structure is mainly in the form of a recovery state. The refinement of the grains makes the yield strength of the magnesium alloy consistent with the rolled state, and the heating temperature is controlled at 150°C to 200°C, the grains will not grow significantly, the uniformity of the grain size can be guaranteed, and the strength will not be reduced. Under high-frequency short-time experimental conditions, the magnesium alloy lattice changes drastically, the microstructure does not change significantly, the grains do not recrystallize, and are mainly in the recovery state. The refinement of the grains makes the yield strength of the magnesium alloy consistent with the rolled state, and the strength and plasticity of the AZ31B magnesium plate are improved.

[0019] The above-mentioned method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the short-time high-frequency electromagnetic induction heating in step 4 adopts single-sided heating, the heating temperature is the temperature of the back side of the straightened magnesium alloy billet, and the heating is stopped when the heating temperature reaches the set value. In the present invention, the effect of short-time high-frequency electromagnetic induction heating is ensured by controlling the heating method.

[0020] The above-mentioned method for preparing a high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the short-time high-frequency electromagnetic induction heating described in step 4 is performed 1 to 5 times. The present invention controls the number of short-time high-frequency electromagnetic induction heating to observe the influence of different electromagnetic induction heating times on the microstructure of the magnesium alloy. Induction heating 1 to 5 times is a process in which the electron wind force affects the magnesium alloy lattice. The lattice is distorted only under one induction heating condition, and at this time, the current (electron wind) has a greater influence on the magnesium alloy lattice. With the increase in the number of electromagnetic induction heating times, the degree of lattice distortion decreases, and the current has less influence on the dislocations parallel to the electron wind. Finally, a local superlattice is formed, and the dislocation rearrangement leads to a more uniform dislocation distribution, further increasing the plasticity of the AZ31B magnesium alloy.

[0021] The above-mentioned method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating is characterized in that the high-strength and high-plasticity AZ31B magnesium plate described in step four has a yield strength greater than 239 MPa, a tensile strength greater than 282 MPa, and an elongation at break not greater than 12.9%.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention reduces the grain size of the clean magnesium alloy billet by rolling to improve the strength of the magnesium alloy, and then combines short-time high-frequency electromagnetic induction heating to generate a high-density induced current in the straightened magnesium alloy billet for extremely rapid heating, wherein the dynamic recrystallization temperature of the magnesium alloy billet under the action of the current is significantly reduced, and the magnesium alloy is affected by the electron wind, and the lattice is severely distorted, the dislocation density distribution becomes uniform, and the average grain size is reduced. The electron wind force generated by the current can break the atomic bonds and rearrange the lattice atoms. This unique structure improves the strength and plasticity of the magnesium alloy, thereby obtaining a high-strength and high-plasticity AZ31B magnesium plate.

[0024] 2. The present invention controls the rolling parameters to make the microstructure of the rolled magnesium alloy billet uniform, which is more conducive to providing stable raw materials for subsequent short-term high-frequency electromagnetic induction heating, and ensures that the obtained rolled magnesium alloy billet has no edge cracks, surface damage or other damage, etc., thereby ensuring the integrity of the sample.

[0025] 3. The present invention proposes a new short-process technology of "rolling + induction heating", which uses the principle of electromagnetic induction to generate high-density induced current in the magnesium alloy plate for extremely rapid heating. This not only avoids a series of problems of traditional heat treatment methods, but also introduces the influence of current on magnesium alloy, thereby achieving the synergistic effect of high strength and high plasticity of magnesium alloy.

[0026] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a metallographic image of the clean magnesium alloy billet obtained in step 1 of Example 1 of the present invention.

[0028] Figure 2 This is the metallographic diagram of the rolled magnesium alloy billet obtained in step 2 of Example 1 of the present invention.

[0029] Figure 3 This is the metallographic phase diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of Example 1 of the present invention.

[0030] Figure 4 This is the metallographic phase diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of Example 2 of the present invention.

[0031] Figure 5 This is the metallographic phase diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of Example 3 of the present invention.

[0032] Figure 6XRD diagrams of the rolled magnesium alloy billet obtained in step 2 of Example 3 of the present invention, the straightened magnesium alloy billet subjected to short-time high-frequency electromagnetic induction heating in step 4, and the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4.

[0033] Figure 7 It is a tensile curve diagram of the clean magnesium alloy billet obtained in step 1 of Example 3 of the present invention, the straightened magnesium alloy billet subjected to a short-time high-frequency electromagnetic induction heating in step 4, and the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4. DETAILED DESCRIPTION

[0034] Example 1

[0035] This embodiment includes the following steps:

[0036] Step 1, surface treatment: the AZ31B magnesium alloy blank was polished with 400# and 600# sandpaper in turn, then cleaned with anhydrous ethanol, and finally dried for 1h to obtain a clean magnesium alloy blank of 60mm×50mm×11mm (length×width×thickness);

[0037] Step 2, rolling: the clean magnesium alloy billet obtained in step 1 is kept at 360° C. for 30 minutes, and then rolled for 4 times at a rolling speed of 10 m / min, a pressing amount of 10% per pass, and a total pressing amount of 45% to 50%. The time for returning to the furnace and keeping warm after the first rolling of the multi-pass rolling is 19 minutes, and the time for returning to the furnace and keeping warm after the second rolling and subsequent rolling passes is 9 minutes, to obtain a rolled magnesium alloy billet with a thickness of 6.5 mm;

[0038] Step 3, straightening: cold straightening the rolled magnesium alloy billet obtained in step 2 to obtain a straightened magnesium alloy billet;

[0039] Step 4, short-time high-frequency electromagnetic induction heating: the straightened magnesium alloy billet obtained in step 3 is subjected to short-time high-frequency electromagnetic induction heating at a frequency of 380kHz, and the distance between the heating coil of the short-time high-frequency electromagnetic induction heating and the straightened magnesium alloy billet is 0.5mm. The short-time high-frequency electromagnetic induction heating adopts single-sided heating, and the heating temperature is the temperature of the heated back side of the straightened magnesium alloy billet. When the temperature reaches 150°C, the heating is stopped. The heating time is 3s to 4s, and the high-strength and high-plasticity AZ31B magnesium plate is obtained by cooling at room temperature.

[0040] According to tests, the high-strength and high-plasticity AZ31B magnesium plate prepared in this embodiment has a yield strength of 253 MPa, a tensile strength of 287 MPa, and an elongation at break of 6.5%.

[0041] Figure 1 The metallographic image of the clean magnesium alloy blank obtained in step 1 of this embodiment is shown in FIG. Figure 1It can be seen that the grain size in the magnesium alloy without rolling and electromagnetic induction heating is uneven, and there is also a significant difference in the grain size between the edge and the center.

[0042] Figure 2 is the metallographic diagram of the rolled magnesium alloy billet obtained in step 2 of this embodiment, Figure 2 The left picture in the middle shows the left part of the rolled magnesium alloy billet, the middle picture shows the middle part of the rolled magnesium alloy billet, and the right picture shows the right part of the rolled magnesium alloy billet. Figure 2 It can be seen from the figure that the grains in the rolled magnesium alloy billet after rolling are fine and there are some twins.

[0043] Figure 3 This is the metallographic diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of this embodiment. Figure 3 The left picture in the middle is the left part of the high-strength and high-plasticity AZ31B magnesium plate, the middle picture is the middle part of the high-strength and high-plasticity AZ31B magnesium plate, and the right picture is the right part of the high-strength and high-plasticity AZ31B magnesium plate. Figure 3 It can be seen that the overall grains are relatively small, the number of grain boundaries is increased compared with the rolled state, and more necklace-shaped fine grains appear at the grain boundaries. At this time, it can be seen that the organization is all deformed, and super-large grains appear locally. The microstructure is not as uniform as the rolled state.

[0044] Example 2

[0045] This embodiment includes the following steps:

[0046] Step 1, surface treatment: the AZ31B magnesium alloy blank was polished with 400# and 600# sandpaper in turn, then cleaned with anhydrous ethanol, and finally dried for 1h to obtain a clean magnesium alloy blank of 60mm×50mm×10mm (length×width×thickness);

[0047] Step 2, rolling: the clean magnesium alloy billet obtained in step 1 is kept at 340°C for 30 minutes, and then rolled for 4 times at a rolling speed of 9m / min, a pressing amount of 12% per pass, and a total pressing amount of 45% to 50%. The time for returning to the furnace and keeping warm after the first rolling of the multi-pass rolling is 18 minutes, and the time for returning to the furnace and keeping warm after the second rolling and the subsequent rolling is 8 minutes, so as to obtain a rolled magnesium alloy billet with a thickness of 5.5mm;

[0048] Step 3, straightening: cold straightening the rolled magnesium alloy billet obtained in step 2 to obtain a straightened magnesium alloy billet;

[0049] Step 4, short-time high-frequency electromagnetic induction heating: the straightened magnesium alloy billet obtained in step 3 is subjected to short-time high-frequency electromagnetic induction heating at a frequency of 360kHz, and the distance between the heating coil of the short-time high-frequency electromagnetic induction heating and the straightened magnesium alloy billet is 0.5mm. The short-time high-frequency electromagnetic induction heating adopts single-sided heating, and the heating temperature is the temperature of the heated back side of the straightened magnesium alloy billet. When the temperature reaches 170°C, the heating is stopped, and the electromagnetic induction heating is performed again after cooling to room temperature, and the heating is repeated 3 times. The total heating time is 9s to 12s to obtain a high-strength and high-plasticity AZ31B magnesium plate.

[0050] According to tests, the high-strength and high-plasticity AZ31B magnesium plate prepared in this embodiment has a yield strength of 239 MPa, a tensile strength of 286 MPa, and an elongation at break of 10.9%.

[0051] Figure 4 This is the metallographic diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of this embodiment. Figure 4 The left picture in the middle is the left part of the high-strength and high-plasticity AZ31B magnesium plate, the middle picture is the middle part of the high-strength and high-plasticity AZ31B magnesium plate, and the right picture is the right part of the high-strength and high-plasticity AZ31B magnesium plate. Figure 4 It can be seen that the grain size has basically not changed compared with the first time, the grain structure is still mainly deformed, and no recrystallization occurs. However, the grain boundaries between the grains become longer, and the grain growth direction tends to be more in the same direction, so the plasticity increases.

[0052] Example 3

[0053] This embodiment includes the following steps:

[0054] Step 1, surface treatment: the AZ31B magnesium alloy blank was polished with 400# and 600# sandpaper in turn, then cleaned with anhydrous ethanol, and finally dried for 1h to obtain a clean magnesium alloy blank of 60mm×50mm×13mm (length×width×thickness);

[0055] Step 2, rolling: the clean magnesium alloy billet obtained in step 1 is kept at 320° C. for 30 minutes, and then multi-pass rolling is performed at a rolling speed of 11 m / min, a pressing amount of 8% per pass, and a total pressing amount of 50% to 55%. The time for returning to the furnace and keeping warm after the first rolling of the multi-pass rolling is 20 minutes, and the time for returning to the furnace and keeping warm after the second rolling and subsequent rolling passes is 10 minutes, to obtain a rolled magnesium alloy billet with a thickness of 7 mm;

[0056] Step 3, straightening: cold straightening the rolled magnesium alloy billet obtained in step 2 to obtain a straightened magnesium alloy billet;

[0057] Step 4, short-time high-frequency electromagnetic induction heating: the straightened magnesium alloy billet obtained in step 3 is subjected to short-time high-frequency electromagnetic induction heating at a frequency of 340kHz, and the distance between the heating coil of the short-time high-frequency electromagnetic induction heating and the straightened magnesium alloy billet is 0.5mm. The short-time high-frequency electromagnetic induction heating adopts single-sided heating, and the heating temperature is the temperature of the heated back side of the straightened magnesium alloy billet. When the temperature reaches 190°C, the heating is stopped, and the electromagnetic induction heating is performed again after cooling to room temperature, and the heating is repeated 5 times. The total heating time is 16s to 19s to obtain a high-strength and high-plasticity AZ31B magnesium plate.

[0058] According to tests, the high-strength and high-plasticity AZ31B magnesium plate prepared in this embodiment has a yield strength of 239 MPa, a tensile strength of 282 MPa, and an elongation at break of 12.9%.

[0059] Figure 5 This is the metallographic diagram of the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 of this embodiment. Figure 5 The left picture in the middle is the left part of the high-strength and high-plasticity AZ31B magnesium plate, the middle picture is the middle part of the high-strength and high-plasticity AZ31B magnesium plate, and the right picture is the right part of the high-strength and high-plasticity AZ31B magnesium plate. Figure 5 It can be seen that the grains have not grown and the structure is composed of large and small grains.

[0060] Figure 6 The XRD diagrams of the rolled magnesium alloy billet obtained in step 2 of this embodiment, the straightened magnesium alloy billet subjected to a short-time high-frequency electromagnetic induction heating in step 4, and the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 are shown in FIG. Figure 6 The magnesium alloy billet subjected to medium rolling is named rolling, the magnesium alloy billet subjected to short-time high-frequency electromagnetic induction heating is named REIH1, and the high-strength and high-ductility AZ31B magnesium plate is named REIH5. The ND surface is selected as the test surface. Figure 6 It can be seen that the (0002) basal plane peak is significantly enhanced with the increase of the number of induction heating times, and the peaks of other planes such as (1011), (1012) and (1013) are all enhanced. The introduction of current makes the material affected by the electron wind, and the grains spin, so that the grains with similar orientations tend to one orientation, so the XRD shows an enhanced peak. The enhancement of other non-basal planes indicates that the influence of the electron wind on the lattice is not two-dimensional, and it will affect other orientations and planes.

[0061] The clean magnesium alloy blank obtained in step 1 of this embodiment, the straightened magnesium alloy blank subjected to short-time high-frequency electromagnetic induction heating in step 4, and the high-strength and high-plasticity AZ31B magnesium plate obtained in step 4 were subjected to tensile tests using an electronic universal testing machine. The results are as follows: Figure 7 , Figure 7The clean magnesium alloy billet is named initial, the straightened magnesium alloy billet after a short-time high-frequency electromagnetic induction heating is named REIH1, and the high-strength and high-plasticity AZ31B magnesium plate is named REIH5. Figure 7 It can be seen that the strength of the samples after rolling and induction heating treatment is improved, and the strength remains almost consistent. With the increase in the number of heating times, the plasticity is improved. The strength and plasticity of the samples heated 5 times are greatly improved, proving that high-strength-plastic AZ31B magnesium alloy can be prepared by rolling and electromagnetic induction heating.

[0062] Example 4

[0063] The difference between this embodiment and embodiment 3 is that in step 2, the clean magnesium alloy billet obtained in step 1 is kept at 400° C. for 30 minutes, and in step 4, the straightened magnesium alloy billet obtained in step 3 is subjected to short-term high-frequency electromagnetic induction heating at a frequency of 300 kHz.

[0064] Example 5

[0065] The difference between this embodiment and embodiment 3 is that in step 2, the clean magnesium alloy billet obtained in step 1 is kept at 300° C. for 30 minutes, and in step 4, the straightened magnesium alloy billet obtained in step 3 is subjected to short-term high-frequency electromagnetic induction heating at a frequency of 400 kHz.

[0066] The AZ31B magnesium alloy billets in Examples 1 to 5 of the present invention are composed of the following components in mass fraction: Al 2.5% to 3.5%, Zn 0.6% to 1.4%, Mn 0.2% to 1.0%, Si 0.08%, Ca 0.04%, Fe 0.003%, Cu 0.01%, and the balance is Mg and unavoidable impurities.

[0067] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating, characterized in that: The method comprises the following steps: Step 1: Surface treatment: grinding, cleaning and drying the AZ31B magnesium alloy blank in sequence to obtain a clean magnesium alloy blank; Step 2, rolling: the clean magnesium alloy billet obtained in step 1 is subjected to multiple rolling processes to obtain a rolled magnesium alloy billet; Step 3, straightening: straightening the rolled magnesium alloy billet obtained in step 2 to obtain a straightened magnesium alloy billet; Step 4: Short-time high-frequency electromagnetic induction heating: The straightened magnesium alloy billet obtained in step 3 is subjected to short-time high-frequency electromagnetic induction heating to obtain a high-strength and high-plasticity AZ31B magnesium plate.

2. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The AZ31B magnesium alloy billet in step 1 is composed of the following components by mass fraction: Al 2.5% to 3.5%, Zn 0.6% to 1.4%, Mn 0.2% to 1.0%, Si 0.08%, Ca 0.04%, Fe 0.003%, Cu 0.01%, and the balance is Mg and unavoidable impurities.

3. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The thickness of the AZ31B magnesium alloy blank in step 1 is 10 mm to 13 mm.

4. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The temperature of the multi-pass rolling in step 2 is 300°C to 400°C, the rolling speed is 9m / min to 11m / min, the pressing amount per pass is 8% to 12%, the total pressing amount of the multi-pass rolling is 45% to 55%, the time for returning to the furnace and keeping warm after the first rolling pass is 18min to 20min, and the time for returning to the furnace and keeping warm after the second rolling pass and subsequent rolling passes is 8min to 10min.

5. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The thickness of the magnesium alloy billet rolled in multiple passes in step 2 is 5.5 mm to 7.0 mm.

6. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The straightening described in step 3 is cold straightening.

7. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The frequency of the short-time high-frequency electromagnetic induction heating in step 4 is 300kHz~400kHz, the temperature is 150℃~200℃, the time is 3s~20s, and the distance between the heating coil of the short-time high-frequency electromagnetic induction heating and the straightening magnesium alloy billet is 0.5mm.

8. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The short-time high-frequency electromagnetic induction heating in step 4 adopts single-sided heating, and the heating temperature is the temperature of the heated back side of the straightened magnesium alloy billet. The heating is stopped when the heating temperature reaches the set value.

9. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The short-time high-frequency electromagnetic induction heating described in step 4 is performed 1 to 5 times.

10. The method for preparing high-strength and high-plasticity AZ31B magnesium plate based on short-time high-frequency electromagnetic induction heating according to claim 1, characterized in that: The high-strength and high-plasticity AZ31B magnesium plate in step 4 has a yield strength greater than 239 MPa, a tensile strength greater than 282 MPa, and an elongation at break not greater than 12.9%.

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