CN109694976B - Low-cost soluble magnesium alloy and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of metal materials and processing, and relates to a low-cost soluble magnesium alloy and a preparation method and application thereof, which can be used to prepare relevant parts of shale oil and gas development using multi-stage sliding sleeve staged fracturing technology. The alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following elements by mass percentage: Al 0.20-0.50wt%, Ca 0.20-1.00wt%, Mn 0.30-1.10wt%, Cu 0.10- 1.20wt%, Ni 0.10-0.50wt%, and the rest are Mg and unavoidable impurity elements. The low-cost soluble magnesium alloy prepared by the invention has a tensile strength of ≥280 MPa, a yield strength of ≥240 MPa and an elongation of ≥14%; the dissolution rate in a 93° C., 3% KCl solution is 50-60 mg cm ^{- 2} h ^-1 .

Description

A kind of low-cost soluble magnesium alloy and its preparation method and application

technical field

The invention belongs to the technical field of metal materials and processing, and in particular relates to a low-cost soluble magnesium alloy and a preparation method and application thereof, which can be used to prepare relevant parts of shale oil and gas development using multi-stage sliding sleeve staged fracturing technology.

Background technique

The development of science and technology promotes the continuous improvement of the global industrial automation level, which leads to a further increase in the demand for energy. Shale oil and gas, as one of the important directions of the development of the energy field at present and in the future, has high economic value. The related extraction technology has been successful in the United States and gradually spread to the world. According to statistics, my country's shale gas reserves rank first in the world, and shale oil reserves rank third in the world, with broad prospects for future development. However, the relevant mining technology is still in the starting price range, and the current mainstream technology is the multi-stage sliding sleeve staged fracturing technology commonly used in horizontal well mining. A key component of the technology is the fracturing tool, including temporary plugging balls, ball seats, bridge plugs, and sliding sleeves. The above tools should have the characteristics of dissolvability and good strength and elongation during the fracturing process.

At present, the dissolvable materials developed for the above tools at home and abroad are mostly polymer materials, composite materials, aluminum alloys and magnesium alloys. The mechanical properties of polymer materials are low, and they are not easily decomposed in high-temperature corrosive media. Most of the composite materials use nano-scale metal powder, which greatly increases the material cost and hinders its application and promotion.

The patent "A pressure-resistant and fast-degrading cast aluminum alloy and its preparation method" (application number 201710327729.3) and the patent "a light-weight pressure-resistant and rapidly decomposing cast magnesium alloy" (application number CN201310284659.X) respectively announced a Fast dissolving cast aluminium alloys and cast magnesium alloys. However, the inventors found that the aluminum alloy and magnesium alloy products obtained by the casting process have obvious casting structure characteristics: dendritic structure, relatively coarse grains and different degrees of component segregation; this will lead to low mechanical properties of the products and poor dissolution process. Uneven and stable.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a low-cost soluble magnesium alloy and a preparation method and application thereof. The soluble magnesium alloy of the invention does not contain expensive rare earth elements, and on the basis of realizing low cost, it has both good mechanical properties and a uniform and stable dissolution rate; the alloy is a kind of soluble magnesium with good comprehensive performance. alloy. In the preparation process of the soluble magnesium alloy of the present invention, the extrusion speed can be as high as 20 m/min.

The present invention adopts following technical scheme:

A first aspect of the present invention provides a low-cost soluble magnesium alloy, the low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, and is composed of the following elements by mass percentage: Al 0.20-0.50 wt%, Ca 0.20-1.00wt%, Mn 0.30-1.10wt%, Cu 0.10-1.20wt%, Ni 0.10-0.50wt%, and the rest are Mg and inevitable impurity elements.

In the present invention, unavoidable impurities≤0.050%.

In a second aspect of the present invention, a method for preparing the above-mentioned low-cost soluble magnesium alloy is provided, comprising the following steps: weighing pure magnesium ingot, pure aluminum ingot, Mg-Ca master alloy, Mg-Mn master alloy, and Mg-Cu intermediate Alloy, Mg-Ni intermediate alloy; pass in protective gas and smelt, cast into ingot; homogenize the ingot, cut into billets of corresponding size and peel; hot extrusion into rod; the hot extrusion The pressing conditions are as follows: the extrusion temperature is 350-400°C, the extrusion ratio is 4-10, and the extrusion speed is 10-20 m/min; the extrusion temperature is preferably 350°C.

The third aspect of the present invention provides the application of the above-mentioned low-cost soluble magnesium alloy in the preparation of soluble parts in the process of shale oil and gas exploitation.

The present invention achieves beneficial results:

(1) The Mg-Al-Ca-Mn-Cu-Ni alloy of the present invention refines the grain size of the ingot through Mn and Ca, thereby reducing the segregation of the ingot, making the Cu and Ni in the material evenly distributed, and forming fine and dispersed Mg ₂ Cu and Mg ₂ Ni to achieve the purpose of uniform dissolution. The low-cost soluble magnesium alloy prepared by the invention has a tensile strength of ≥280 MPa, a yield strength of ≥240 MPa and an elongation of ≥14%; the dissolution rate in a 93° C., 3% KCl solution is 50-60 mg cm ^-2 h ^-1 .

(2) The alloy of the present invention weakens the basal texture of the magnesium alloy by adding Ca element, thereby increasing the elongation of the material. In addition, Ca itself has flame retardant and anti-oxidation effects, which improves the ignition point of the alloy. Therefore, the amount of shielding gas is reduced during the smelting process; gas shielding is not required during the homogenization process, and the extrusion rate can be as high as 20m/min during the extrusion process.

(3) In the present invention, a small amount of Al element is added to the alloy. On the one hand, the strength of the material is improved by solid solution strengthening, and on the other hand, a small amount of high melting point (Mg, Al) ₂ Ca and Al ₈ Mn ₅ can be formed in the second phase. , to improve the strength of the material by means of dispersion strengthening.

(4) The soluble magnesium alloy of the present invention can be rapidly extruded at a high temperature of 350-400° C. and an extrusion ratio of less than 10 to obtain a soluble magnesium alloy with good mechanical properties. "Deformation through shielding gas" and "small extrusion ratio" can reduce deformation resistance during processing, increase forming rate, and reduce equipment loss; asset investment.

(5) Only a small amount of relatively expensive Ni element is added to the soluble magnesium alloy of the present invention, which increases the cost of the alloy less; at the same time, the material processing rate is high and the cost is low, so the application prospect is good.

Description of drawings

The accompanying drawings forming a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention.

FIG. 1 shows the microstructure of the magnesium alloy prepared in Test Example Group 1.

FIG. 2 is the microstructure of the magnesium alloy prepared in Test Example Group 6. FIG.

Detailed ways

It should be noted that the following detailed description is exemplary and intended to provide further explanation of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terminology used herein is for the purpose of describing specific embodiments only, and is not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural as well, furthermore, it is to be understood that when the terms "comprising" and/or "including" are used in this specification, it indicates that There are features, steps, operations, and/or combinations thereof.

In view of the problems described in the background art, the first aspect of the present invention provides a low-cost soluble magnesium alloy, the low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following mass percentages Elemental composition: Al 0.20-0.50wt%, Ca 0.20-1.00wt%, Mn 0.30-1.10wt%, Cu 0.10-1.20wt%, Ni 0.10-0.50wt%, and the rest are Mg and inevitable impurity elements.

Further, the low-cost soluble magnesium alloy is composed of the following elements by mass percentage: Al 0.30-0.50wt%, Ca 0.80-1.00wt%, Mn 0.30-0.70wt%, Cu 0.30-0.90wt%, Ni 0.20-0.40 wt%, and the rest are Mg and inevitable impurity elements.

Further, the low-cost soluble magnesium alloy is composed of the following elements by mass percentage: Al 0.50wt%, Ca 0.90wt%, Mn 0.55wt%, Cu 0.40wt%, Ni 0.30wt%, and the rest are Mg and unavoidable impurity elements.

Due to its active chemical properties, magnesium alloys are prone to oxidative combustion during smelting and casting without protection. Moderate alloying can increase the ignition temperature of the alloy and reduce costs and accident risks during smelting and casting. In addition, magnesium alloys It belongs to the close-packed hexagonal metal structure, with less slip system at room temperature, and requires hot forming processing, while high alloying will increase the material cost and reduce its forming performance at the same time. Defects such as oxidation and cracks are prone to occur during extrusion. Therefore, the selection and content control of alloying elements have a significant impact on the processing cost and product quality, mechanical properties, and dissolution rate of the material. The magnesium alloy of the present invention achieves the goals of low cost, easy forming, medium strength and elongation, and solubility by optimizing alloy elements and their contents.

Al is the most economical element for enhancing the strength of wrought magnesium alloys. Ca element can significantly increase the ignition temperature of magnesium alloys and refine the ingot structure. Mn element can also refine the grain structure of magnesium alloy ingots. In addition, Al and Ca can form a higher melting point (Mg,Al) ₂ Ca phase with Mg; Al and Mn elements can also form a high melting point Al ₈ Mn ₅ phase. The microalloying of Al, Ca and Mn not only improves the strength of magnesium alloy, but also maintains a good elongation.

Traditionally, it is believed that Cu and Ni are impurity elements that increase the corrosion rate of magnesium alloys. By controlling the contents of Cu and Ni elements, the invention obtains fine Mg2Cu and Mg2Ni phases in the magnesium alloy structure, so that the soluble magnesium alloy can be prepared.

In a second aspect of the present invention, a method for preparing the above-mentioned low-cost soluble magnesium alloy is provided, comprising the following steps: weighing pure magnesium ingot, pure aluminum ingot, Mg-Ca master alloy, Mg-Mn master alloy, and Mg-Cu intermediate Alloy, Mg-Ni intermediate alloy; pass in protective gas and smelt, cast into ingot; homogenize the ingot, cut into billets of corresponding size and peel; hot extrusion into rod; the hot extrusion The pressing conditions are as follows: the extrusion temperature is 350-400°C, the extrusion ratio is 4-10, and the extrusion speed is 10-20 m/min; the extrusion temperature is preferably 350°C. In the method of the invention, the extrusion ratio is small, the extrusion speed is large, and the equipment loss is reduced.

Further, the hot extrusion conditions are: extrusion temperature of 350° C., extrusion ratio of 8, and extrusion speed of 20 m/min. The soluble magnesium alloy prepared under the hot extrusion conditions has the best properties such as solubility, tensile strength and elongation. By adopting the above-mentioned lower extrusion ratio, the present invention can prepare rods of larger size, and at the same time, the tonnage of the required extruder equipment can be reduced.

Further, the steps of smelting and pouring into ingots include: mixing pure magnesium ingots, pure aluminum ingots, Mg-Ca master alloys, Mg-Mn master alloys, Mg-Cu master alloys, and Mg-Ni master alloys according to the proportions. Weigh, introduce protective gas, smelt at 720～740℃, keep warm for 40～60min, stir for 5～10min, and refine for 20～30min. Pouring into an ingot; preferably, smelting at 730°C, holding for 60 minutes, stirring for 10 minutes, and refining for 20 minutes. After refining, the temperature is raised to 760°C and left to stand for 40 minutes.

Further, the protective gas used is a mixed gas of CO ₂ and SF ₆ , and the volume ratio of CO ₂ and SF ₆ is 200-400:1; preferably, the volume ratio of CO ₂ and SF ₆ is 300:1. The mixed gas has the most significant effect of preventing oxidation during the alloy preparation process.

Further, the conditions of the homogenization treatment are to carry out the homogenization treatment at 480-520°C for a holding time of 1-4h, the cooling method is air cooling, and then cut into corresponding blanks and peeled; preferably, at 500°C The homogenization treatment was carried out for a holding time of 2h. The invention adopts a higher homogenization temperature, on the one hand, it can promote the microalloy to dissolve into the magnesium alloy matrix as soon as possible, and reduce the heat treatment cost;

The third aspect of the present invention provides the application of the above-mentioned low-cost soluble magnesium alloy in the preparation of soluble parts in the process of shale oil and gas exploitation.

Further, the application of the above-mentioned low-cost soluble magnesium alloy in the preparation of relevant parts for shale oil and gas development using multi-stage sliding sleeve staged fracturing technology. The soluble magnesium alloy of the invention has the advantages of fast dissolution rate, high tensile strength and the like, and has broad application prospects in the preparation of related parts and components of the multi-stage sliding sleeve staged fracturing technology for shale oil and gas development.

In order to enable those skilled in the art to understand the technical solutions of the present invention more clearly, the technical solutions of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

Embodiment 1 A kind of low-cost soluble magnesium alloy

The low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following elements by mass percentage: Al 0.50wt%, Ca 0.90wt%, Mn 0.55wt%, Cu 0.40wt%, Ni is 0.30wt%, and the rest is Mg and inevitable impurity elements.

Embodiment 2 A kind of low-cost soluble magnesium alloy

The low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following elements by mass percentage: Al 0.40wt%, Ca 0.50wt%, Mn 0.45wt%, Cu 0.90wt%, Ni is 0.10wt%, and the rest is Mg and unavoidable impurity elements.

Embodiment 3 A kind of low-cost soluble magnesium alloy

The low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following elements by mass percentage: Al 0.30wt%, Ca 1.00wt%, Mn 0.90wt%, Cu 1.0wt%, Ni is 0.50wt%, and the rest is Mg and unavoidable impurity elements.

Embodiment 4 A kind of low-cost soluble magnesium alloy

The low-cost soluble magnesium alloy is a Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, which is composed of the following elements by mass percentage: Al 0.40wt%, Ca 1.00wt%, Mn 1.00wt%, Cu 1.2wt%, Ni is 0.50wt%, and the rest is Mg and unavoidable impurity elements.

Embodiment 5 A kind of preparation method of low-cost soluble magnesium alloy

The raw materials are: pure magnesium ingot, pure aluminum ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy, Mg-30%Cu master alloy, Mg-25%Ni master alloy.

The raw materials are weighed according to the proportion. The above raw materials are pure magnesium ingot, pure aluminum ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy; protected by CO ₂ +SF ₆ mixed gas (volume ratio of 300:1) Under the condition of smelting at 720 ℃, heat preservation for 60 minutes, stirring for 10 minutes, and refining for 20 minutes, after refining, the temperature was raised to 740 ℃ and left to stand for 30 minutes, and cast into ingots at 720 ℃.

The above-mentioned ingots were homogenized at 520° C. for a holding time of 2 hours, and the cooling method was air cooling, and then cut into corresponding billets and peeled.

The blank obtained in the previous step is extruded into a rod through an extruder at an extrusion temperature of 350° C., an extrusion ratio of 5, and an extrusion speed of 20 m/min.

Embodiment 6 A kind of preparation method of low-cost soluble magnesium alloy

The raw materials are: pure magnesium ingot, pure aluminum ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy, Mg-30%Cu master alloy, Mg-25%Ni master alloy.

The raw materials are weighed according to the proportion, and the above raw materials are pure magnesium ingot, pure aluminum ingot, pure tin ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy; in CO ₂ +SF ₆ mixed gas (volume ratio is 400 : 1) Under the protection conditions, smelting at 740 ℃, heat preservation for 40 minutes, stirring for 5 minutes, and refining for 30 minutes, after refining, the temperature is raised to 760 ℃ and left to stand for 40 minutes, and cast into an ingot at 740 ℃.

The above-mentioned ingots were homogenized at 500° C. for a holding time of 2 hours, and the cooling method was air cooling, and then cut into corresponding billets and peeled.

The billet obtained in the previous step is extruded into a bar through an extruder at an extrusion temperature of 400° C., an extrusion ratio of 8, and an extrusion speed of 20 m/min.

Embodiment 7 A kind of preparation method of low-cost soluble magnesium alloy

The raw materials are: pure magnesium ingot, pure aluminum ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy, Mg-30%Cu master alloy, Mg-25%Ni master alloy.

The raw materials are weighed according to the proportion, and the above raw materials are pure magnesium ingot, pure aluminum ingot, pure tin ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy; in CO ₂ +SF ₆ mixed gas (volume ratio is 400 : 1) Under the protection conditions, smelt at 720°C, keep warm for 40min, stir for 5min, and refine for 30min. After refining, heat up to 750°C and let stand for 30min, and cast into an ingot at 730°C.

The above-mentioned ingots were homogenized at 510° C. for a holding time of 1 hour, and the cooling method was air cooling, and then cut into corresponding billets and peeled.

The billet obtained in the previous step was extruded into a rod through an extruder at an extrusion temperature of 390° C., an extrusion ratio of 10, and an extrusion speed of 10 m/min.

Embodiment 8 A kind of preparation method of low-cost soluble magnesium alloy

The raw materials are: pure magnesium ingot, pure aluminum ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy, Mg-30%Cu master alloy, Mg-25%Ni master alloy.

The raw materials are weighed according to the proportion, and the above-mentioned raw materials are pure magnesium ingot, pure aluminum ingot, pure tin ingot, Mg-25%Ca master alloy, Mg-10%Mn master alloy; in CO ₂ +SF ₆ mixed gas (volume ratio of 300 : 1) Under the protection conditions, smelt at 720°C, keep warm for 40min, stir for 10min, and refine for 30min. After refining, heat up to 740°C and let stand for 30min, and cast it into an ingot at 720°C.

The above-mentioned ingots were homogenized at 500° C. for a holding time of 2 hours, and the cooling method was air cooling, and then cut into corresponding billets and peeled.

The billet obtained in the previous step is extruded into a rod through an extruder at an extrusion temperature of 380° C., an extrusion ratio of 10, and an extrusion speed of 5 m/min.

Comparative Example 1

The comparison alloy is as-cast AZ91D magnesium alloy, the chemical composition of the alloy is: Mg-9.0wt%Al-0.80wt%Zn-0.3wt%Mn-0.025wt%Cu, alloy ingredients (raw materials: pure magnesium ingot, pure aluminum ingot, pure zinc ingot, Mg-10%Mn master alloy, Mg-30%Cu master alloy).

Comparative Example 2:

The difference from Example 1 is that the mass percentages of Mg-Al-Ca-Mn-Cu-Ni alloy elements are: Al 0.70wt%, Ca 1.20wt%, Mn 1.00wt%, Cu 1.5wt%, Ni 1.50wt% The rest are Mg and inevitable impurity elements.

Comparative Example 3:

The difference from Example 1 is that the mass percentages of Mg-Al-Ca-Mn-Cu-Ni alloy elements are: Al 0.30wt%, Ca 0.20wt%, Mn 0.10wt%, Cu 0.05wt%, Ni 0.05wt% The rest are Mg and inevitable impurity elements.

Comparative Example 4

The difference from Example 7 is that the extrusion temperature is 450° C., the extrusion ratio is 10, and the extrusion speed is 10 m/min.

Comparative Example 5

The difference from Example 5 is that the extrusion ratio is 40 and the extrusion speed is 10 m/min, and the rod is extruded.

Comparative Example 6

The difference from Example 5 is that the extrusion ratio is 80 and the extrusion speed is 10 m/min, and the rod is extruded.

Test example

Group 1: The alloy of Example 1 was prepared according to the method of Example 5;

Group 2: The alloy of Example 2 was prepared by the method of Example 6;

Group 3: The alloy of Example 3 was prepared by the method of Example 7;

Group 4: The alloy of Example 4 was prepared according to the method of Example 8;

Group 5: Comparative Example 1 alloy was prepared by the method of Example 5;

Group 6: Comparative Example 2 alloy was prepared by the method of Example 5;

Group 7: Comparative Example 3 alloy was prepared by the method of Example 5;

Group 8: The alloy of Example 1 was prepared by the method of Comparative Example 4;

Group 9: The alloy of Example 1 was prepared by the method of Comparative Example 5;

Group 10: The alloy of Example 1 was prepared by the method of Comparative Example 6;

The mechanical properties and solubility of each combination of gold were measured;

The mechanical properties test method is performed according to GB T 228.1-2010.

的试样置于93℃的质量分数为3％KCl水溶液中，测试每小时溶解的重量。溶解速率为：溶解的重量/(试样表面积×时间)。The dissolution performance test conditions are:

The sample was placed in a 3% KCl aqueous solution at 93°C, and the dissolved weight per hour was measured. The dissolution rate is: weight dissolved/(sample surface area x time).

Table 1 Room temperature mechanical properties and high temperature dissolution rate of magnesium alloys

Comparing the room temperature mechanical properties and high temperature dissolution rate of the magnesium alloys of the examples and the comparative examples, it can be seen that the room temperature mechanical properties of the low-cost soluble magnesium alloy prepared by the present invention are obviously better than those of the comparative example alloy, and the alloy of the present invention is 93 The dissolution rate in ℃, 3% KCl solution is obviously better than that of the comparative alloy.

It can be seen from the microstructures of the alloys of Test Example Group 1 and Test Example Group 6: the grain size of the material prepared by the present invention is uniform and fine; and the second phase is more dispersed (as shown in Figure 1 and Figure 2). Therefore, its room temperature mechanical properties are significantly better than those of the comparative alloys.

Comparing the test example groups 1, 9 and 10, it can be seen that the mechanical properties of the material are further enhanced as the extrusion ratio increases. The invention can achieve better performance by adopting a smaller extrusion ratio, which is beneficial to the popularization and application of the alloy and the preparation method.

To sum up, the low-cost dissolvable magnesium alloy of the present invention can meet the performance requirements of different components related to the multi-stage sliding sleeve staged fracturing technology in the shale oil and gas exploitation process.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, The simplification should be equivalent replacement manners, which are all included in the protection scope of the present invention.

Claims (14)

1. a low-cost soluble magnesium alloy, is characterized in that, described alloy is Mg-Al-Ca-Mn-Cu-Ni magnesium alloy, is made up of the element of following mass percentage: Al 0.20～0.50wt%, Ca 0.20～ 1.00 wt %, Mn 0.30~1.10 wt %, Cu 0.10~1.20 wt %, Ni 0.10~0.50 wt %, and the rest are Mg and inevitable impurity elements. 2. The low-cost soluble magnesium alloy according to claim 1, characterized in that, it is composed of the following elements by mass percentage: Al 0.30-0.50 wt %, Ca 0.80-1.00 wt %, Mn 0.30-0.70 wt %, Cu 0.30 wt % ~0.90 wt %, Ni 0.20~0.40 wt %, and the rest are Mg and inevitable impurity elements. 3. The low-cost soluble magnesium alloy according to claim 1, characterized in that, it is composed of the following elements by mass percentage: Al 0.50 wt %, Ca 0.90 wt %, Mn 0.55 wt %, Cu 0.40 wt %, Ni 0.30 wt % %, and the rest are Mg and inevitable impurity elements. 4. the preparation method of the low-cost soluble magnesium alloy described in any one of claim 1～3, is characterized in that, comprises the following steps: take by weighing pure magnesium ingot, pure aluminum ingot, Mg-Ca master alloy, Mg-Mn master alloy , Mg-Cu master alloy, Mg-Ni master alloy; pass protective gas and smelt, pour into ingots; homogenize the ingots, cut into billets of corresponding size and peel; hot extrusion into bars ; The hot extrusion conditions are: extrusion temperature 350~400°C, extrusion ratio 4~10, extrusion speed 10~20m/min. 5 . The preparation method according to claim 4 , wherein the extrusion temperature is 350° C. 6 . 6 . The preparation method according to claim 4 , wherein the hot extrusion conditions are: an extrusion temperature of 350° C., an extrusion ratio of 8, and an extrusion speed of 20 m/min. 7 . 7. preparation method according to claim 4, is characterized in that, described smelting, the step of casting into ingot comprises: pure magnesium ingot, pure aluminum ingot, Mg-Ca master alloy, Mg-Mn master alloy, Mg -Cu master alloy and Mg-Ni master alloy are weighed according to the proportions, passed in protective gas, smelted at 720~740℃, kept for 40~60min, stirred for 5~10min, refined for 20~30min, and heated to 740~740℃ after refining Stand at 760°C for 30~40min, and cast into ingots at 720~740°C. 8. The preparation method according to claim 7, characterized in that, smelting at 730°C, keeping the temperature for 60min, stirring for 10min, and refining for 20min, after refining, the temperature is raised to 760°C and left to stand for 40min, and cast into an ingot at 720°C. 9 . The preparation method according to claim 4 , wherein the protective gas used is a mixed gas of CO ₂ and SF ₆ , and the volume ratio of CO ₂ and SF ₆ is 200-400:1. 10 . 10 . The preparation method according to claim 9 , wherein the volume ratio of CO ₂ and SF ₆ is 300:1. 11 . 11. preparation method according to claim 4 is characterized in that, the condition of described homogenization treatment is to carry out homogenization treatment at 480～520 ℃ for holding time 1～4h, cooling mode is air cooling, and then cut into corresponding blanks and peeled. 12 . The preparation method according to claim 11 , wherein the homogenization treatment is carried out at 500° C. for a holding time of 2 h. 13 . 13. The application of the low-cost soluble magnesium alloy according to any one of claims 1 to 3 in the preparation of soluble parts in the process of shale oil and gas exploitation. 14. The application according to claim 13, characterized in that it is an application in the preparation of related parts and components of shale oil and gas development using multi-stage sliding sleeve staged fracturing technology.

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