A high-toughness skateboard shell and method of making the same

Abstract

The application discloses a high-toughness skateboard shell, which comprises the following raw materials in percentage by weight: carbon 0.35-0.42%, chromium 8.5-9.5%, silicon 1.8-2.2%, molybdenum 0.8-1.1%, nickel 1.5-2.4%, vanadium 0.1-0.2%, titanium 0.05-0.1%, boron 0.001-0.003%, rare earth pre-alloy 0.03-0.07%, and the balance of iron and inevitable impurities; wherein the rare earth pre-alloy is composed of lanthanum, cerium, yttrium, aluminum and magnesium. The application aims at solving the technical problem of low toughness of the skateboard shell.

Description

Technical Field

[0001] This invention belongs to the technical field of skateboard brick auxiliary components, and particularly relates to a high-toughness skateboard shell and its preparation method. Background Technology

[0002] Slide block is a key component for controlling the flow of molten steel in continuous casting and is widely used in the iron and steel metallurgical industry. Slide blocks are typically used in conjunction with a steel shell, which provides support, protection, and facilitates installation and fixation. During continuous casting, the slide block and shell are frequently subjected to the impact of molten steel, high-temperature baking, and mechanical vibration, which places high demands on the performance of the slide shell, especially in terms of toughness.

[0003] Currently, most existing slide block shells are made of ordinary carbon steel or low-alloy steel, whose toughness often fails to meet practical application requirements. During long-term use, slide block shells are prone to cracking, deformation, and even breakage. This not only affects the normal use of the slide block and shortens its service life, but may also lead to safety hazards such as molten steel leakage, seriously impacting the stability and safety of continuous casting production. Summary of the Invention

[0004] This invention provides a high-toughness skateboard shell and its preparation method, in order to solve the technical problem of low toughness in current skateboard shells.

[0005] In view of this, the present invention provides a high-toughness skateboard shell comprising the following raw materials by weight percentage: carbon 0.35-0.42%, chromium 8.5-9.5%, silicon 1.8-2.2%, molybdenum 0.8-1.1%, nickel 1.5-2.4%, vanadium 0.1-0.2%, titanium 0.05-0.1%, boron 0.001-0.003%, rare earth pre-alloy 0.03-0.07%, with the balance being iron and unavoidable impurities.

[0006] Optionally, the rare earth pre-alloy is composed of lanthanum, cerium, yttrium, aluminum, and magnesium.

[0007] Optionally, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium is (3-4):(2-3):1:(0.8-1.2):(0.2-0.4).

[0008] Optionally, the rare earth pre-alloy is prepared by the following method: lanthanum, cerium, yttrium, aluminum and magnesium are melted under an inert gas, kept at a constant temperature, and powdered to obtain pre-alloy powder, which is then pressed into alloy wire to obtain rare earth pre-alloy.

[0009] Furthermore, the rare earth pre-alloy is prepared by the following method: lanthanum, cerium, yttrium, aluminum and magnesium are melted under an inert gas (nitrogen or argon), kept at a constant temperature, and powdered to obtain pre-alloy powder with a particle size of 30-80 μm. The pre-alloy powder is then pressed into alloy wire with a diameter of 5-8 mm to obtain the rare earth pre-alloy.

[0010] More preferably, the pre-alloyed powder has a particle size of 50 μm and the alloy wire has a diameter of 6.5 mm.

[0011] Optionally, the melting temperature is 850-950℃, the holding time is 30-60min, the molten pre-alloy is powdered by water atomization, the atomization pressure is 8-12MPa, the water temperature is 20-30℃, and the pressure for pressing into alloy wire is 200-300MPa.

[0012] Furthermore, the melting temperature is 900℃, the holding time is 45min, the molten pre-alloy is powdered using water atomization, the atomization pressure is 10MPa, the water temperature is 25℃, and the pressure for pressing into alloy wire is 250MPa.

[0013] Optionally, the oxygen content of the pre-alloyed powder is ≤0.05wt%, the loose packing density is 2.5-3.0g / cm3, and the density of the alloy wire is ≥96%.

[0014] A method for preparing a high-toughness skateboard shell includes the following steps: heating each raw material to a certain temperature for initial melting, then continuing to heat and hold the temperature while stirring continuously to form molten steel, adding rare earth pre-alloys, letting it stand, casting to form a billet, and then subjecting the billet to a two-stage heat treatment to obtain the skateboard shell.

[0015] Furthermore, a method for preparing a high-toughness skateboard shell includes the following steps: First, heat each raw material to 1450-1500℃ at a rate of 15-20℃ / min for initial melting, then continue heating to 1530-1560℃ and hold for 1-2 hours with continuous stirring to form molten steel. Add rare earth pre-alloys and let stand for 10-15 minutes. Then, preheat the mold to 200-300℃, and pour the settled molten steel into the mold at a casting temperature of 1400-1450℃ and a casting speed of 5-8 kg / s. After casting, allow it to cool naturally to room temperature, demold, and obtain a blank. The blank then undergoes a two-stage heat treatment to obtain the skateboard shell.

[0016] Optionally, the rare earth pre-alloy is added by wire feeding.

[0017] Furthermore, the rare earth pre-alloy is added by wire feeding at a speed of 1.8-2.2 m / s.

[0018] Optionally, the specific steps of the two-stage heat treatment are as follows:

[0019] First stage: Place the billet in a heat treatment furnace and start heating from room temperature. When the temperature reaches 600℃, the heating rate is controlled at 4-6℃ / min. When the temperature exceeds 600℃, adjust the heating rate to 8-12℃ / min and continue heating to 1060-1080℃. Hold the temperature for 2-3 hours. After the holding time is completed, quickly put the billet into oil for cooling. Cool the billet to below 200℃. The cooling rate must be ≥50℃ / s to obtain the quenched billet.

[0020] Second stage: The quenched blank is put back into the heat treatment furnace, and argon gas is introduced at a flow rate of 0.3-0.5 L / min. It is heated to 690-710℃ at a heating rate of 6-10℃ / min and held for 4-6 hours. After the holding is completed, it is cooled to 300℃ in the furnace and then taken out and air-cooled to room temperature to obtain the slide plate shell.

[0021] Furthermore, the specific steps of the two-stage heat treatment are as follows:

[0022] First stage: Place the billet in a heat treatment furnace and start heating from room temperature. When the temperature reaches 600℃, the heating rate is controlled at 5℃ / min. When the temperature exceeds 600℃, the heating rate is adjusted to 10℃ / min, and heating continues to 1070℃. Hold the temperature for 2.5 hours. After the holding time is completed, quickly put the billet into oil for cooling. The oil cooling temperature should be below 200℃, and the cooling rate should be ≥50℃ / s to obtain the quenched billet.

[0023] Second stage: The quenched blank is put back into the heat treatment furnace, argon gas is introduced at a flow rate of 0.4 L / min, and heated to 700℃ at a heating rate of 8℃ / min. It is held at this temperature for 5 hours. After the holding time is completed, it is cooled to 300℃ in the furnace and then taken out and air-cooled to room temperature to obtain the slide plate shell.

[0024] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages:

[0025] 1. This invention uses carbon, chromium, silicon, molybdenum, nickel, vanadium, titanium, boron and iron as the basic raw materials for the skateboard shell. Each element can improve the toughness of the material from multiple dimensions such as grain refinement, grain boundary optimization, microstructure control and defect suppression through individual action and synergistic effect.

[0026] Carbon is a key element for improving material strength. Silicon mainly acts as a deoxidizer, removing oxygen from raw materials. Chromium and molybdenum both improve the hardenability and high-temperature stability of materials. Chromium can dissolve in the iron matrix to form a solid solution, enhancing the matrix's oxidation resistance and corrosion resistance, preventing micro-cracks from forming on the surface of the sliding plate shell due to corrosion in humid or high-temperature environments. Molybdenum can inhibit "aging embrittlement" of materials during long-term use, that is, the material becomes brittle due to the formation of brittle phases caused by internal atomic diffusion. The synergistic effect of these two elements ensures that the sliding plate shell maintains stable toughness under complex working conditions (such as temperature fluctuations and slight corrosion). Nickel is one of the most effective elements for improving the toughness of metallic materials. It can significantly reduce the "brittle transition temperature" of materials, that is, the critical temperature at which a material changes from ductile fracture to brittle fracture. Even under low temperature or impact loads, it can prevent the sliding plate shell from suddenly fractured due to "cold brittleness". Meanwhile, nickel can dissolve in the iron matrix to form a single-phase solid solution, which neither forms brittle intermetallic compounds nor reduces the plasticity of the matrix through solid solution strengthening. When the skateboard shell is subjected to external impact, the matrix can absorb energy through plastic deformation instead of directly generating cracks, thereby greatly improving impact toughness.

[0027] Vanadium and titanium are both strong carbide-forming elements. During material preparation, they combine with carbon to form nanoscale VC, TiC and other carbide particles. These particles are extremely small (usually less than 1 μm) and uniformly distributed. On the one hand, they can improve the strength of the material through "dispersion strengthening" and avoid insufficient strength due to simple toughening. On the other hand, they act as "grain growth inhibitors" - during melting or heat treatment, they hinder the coarsening of iron matrix grains and make the material form a fine and uniform equiaxed crystal structure.

[0028] According to the "Hall-Page relation" in materials mechanics, the finer the grains, the better the strength and toughness of the material: fine grains have more grain boundaries, and when cracks propagate, the grain boundaries will "hinder crack propagation" (the crack needs to constantly change direction to bypass the grain boundaries, consuming more energy), thus significantly improving the crack propagation resistance of the skateboard shell.

[0029] Boron tends to accumulate at grain boundaries in an iron matrix and can form stable low-melting-point compounds with iron and carbon. This distribution improves the "bonding strength" of grain boundaries, preventing "grain boundary embrittlement" caused by impurities (such as sulfur and phosphorus) (in traditional materials, cracks tend to propagate rapidly along weak grain boundaries, leading to brittle fracture). Simultaneously, boron enhances the hardenability of the material, allowing the slide plate shell to achieve a more uniform microstructure (such as bainite or tempered sorbite) during cooling, reducing localized brittle areas caused by microstructure segregation, and indirectly improving overall toughness.

[0030] 2. This invention incorporates rare earth pre-alloys into the raw materials of the skateboard shell. These pre-alloys are composed of lanthanum, cerium, yttrium, aluminum, and magnesium. Through "rare earth purification and impurity removal + regulation of inclusion morphology + optimization of grain boundaries," coupled with "aluminum-magnesium synergistic enhancement (enhanced purification, grain refinement, and improved rare earth distribution)," the toughness of the skateboard shell is improved from three core dimensions: "reducing crack initiation, hindering crack propagation, and enhancing matrix plasticity." Compared to single rare earth elements or traditional raw materials, its advantages are more "comprehensive and stable." It can eliminate hidden defects within the material and enhance overall crack resistance through microstructure optimization. It is more suitable for the complex operating conditions of skateboard shells, significantly reducing the risk of fracture failure, extending service life, and further improving the toughness of the skateboard shell, as detailed below:

[0031] Lanthanum, cerium, and yttrium are highly chemically reactive and can preferentially react with harmful impurities (oxygen, sulfur, phosphorus, nitrogen, etc.) remaining in the raw materials of the skateboard shell.

[0032] It combines with oxygen to form stable rare earth oxides (such as La2O3, CeO2, Y2O3), combines with sulfur to form high-melting-point rare earth sulfides (such as La2S3, CeS), and combines with phosphorus to form rare earth phosphides (such as LaP). The melting points of these compounds are much higher than the preparation temperature of the slide plate shell, and their density is low. They will float to the slag during the smelting process and be removed, thus avoiding the formation of "brittle inclusions" inside the material (such as FeO, FeS, etc., which are common in traditional raw materials. These inclusions are prone to stress concentration under stress and are the main "starting point" for crack initiation).

[0033] Yttrium's purification capabilities are more targeted: compared to lanthanum and cerium, yttrium has a stronger affinity for nitrogen, which can effectively remove trace amounts of nitrogen from raw materials (nitrogen easily forms brittle Fe4N, causing "nitrogen embrittlement" in materials), further reducing "hidden defects" in the matrix and reducing the probability of crack initiation from the root.

[0034] Furthermore, the addition of rare earth elements restricts the anisotropic growth of inclusions, transforming them into "blunt spherical or short rod-shaped inclusions" (such as spherical La-Ce-O composite inclusions). Spherical inclusions exert minimal "cutting effect" on the matrix and exhibit more uniform stress distribution under stress, significantly reducing the risk of crack initiation caused by inclusions. Simultaneously, rare earth elements form stable "low-melting-point grain boundary phases" (such as La-Fe-Al compounds) with elements like iron and aluminum. These phases enhance the "binding strength" of grain boundaries—when cracks propagate to the grain boundaries, more energy is required to break through them, thus delaying or preventing further crack propagation, effectively adding a "crack-resistant barrier" to the material.

[0035] Moreover, aluminum and magnesium are both strong deoxidizing and desulfurizing elements, and their affinity for oxygen is stronger than that of rare earth elements (lanthanum and cerium). The oxides formed by aluminum and magnesium (such as Al2O3) are in the form of fine particles. Rare earth elements can be further adsorbed on the surface of these particles and transformed into "rare earth-aluminum composite oxides" (such as La-Al-O), avoiding the local embrittlement caused by the high hardness and brittleness of pure Al2O3 inclusions.

[0036] 3. This invention employs a two-stage heat treatment process. The core of the first stage is to form a uniform and fine quenched structure (such as martensite or bainite) inside the billet through "stepwise heating + high-temperature holding + rapid oil cooling," while avoiding "inherent defects" such as cracks and compositional segregation during heating / cooling, thus laying the foundation for subsequent toughness improvement. The second stage, based on the quenching in the first stage, transforms the hard and brittle quenched structure (martensite) into a "strong and tough balanced tempered structure" through "medium-temperature holding + protective atmosphere + slow cooling," while completely eliminating internal stress and preventing oxidation, ultimately achieving a significant improvement in toughness. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention can be purchased on the market or prepared by existing methods.

[0038] Preparation Example

[0039] Preparation Example 1

[0040] A rare earth pre-alloy is prepared by the following method:

[0041] Lanthanum, cerium, yttrium, aluminum, and magnesium were smelted under nitrogen at a temperature of 900℃ and held for 45 minutes. The molten pre-alloy was then powdered using a water atomization method at a pressure of 10 MPa and a water temperature of 25℃, resulting in a pre-alloy powder with a particle size of 50 μm. The pre-alloy powder was then pressed into alloy wires with a diameter of 6.5 mm under a pressure of 250 MPa to obtain the rare earth pre-alloy. The weight ratio of lanthanum, cerium, yttrium, aluminum, and magnesium was 3:2:1:0.8:0.2.

[0042] Preparation Example 2

[0043] A rare earth pre-alloy differs from Preparation Example 1 in that the amount of lanthanum added is different. In Preparation Example 2, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium in the rare earth pre-alloy is 3.5:2:1:0.8:0.2.

[0044] Preparation Example 3

[0045] A rare earth pre-alloy differs from Preparation Example 1 in that the amount of lanthanum added is different. In Preparation Example 3, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium in the rare earth pre-alloy is 4:2:1:0.8:0.2.

[0046] Preparation Example 4

[0047] A rare earth pre-alloy differs from Preparation Example 2 in that the amount of cerium added is different. In Preparation Example 4, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium in the rare earth pre-alloy is 3.5:2.5:1:0.8:0.2.

[0048] Preparation Example 5

[0049] A rare earth pre-alloy differs from Preparation Example 2 in that the amount of cerium added is different. In Preparation Example 5, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium in the rare earth pre-alloy is 3.5:3:1:0.8:0.2.

[0050] Preparation Example 6

[0051] A rare earth pre-alloy differs from Preparation Example 4 in that the amounts of aluminum and magnesium added are different. In Preparation Example 6, the weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium in the rare earth pre-alloy is 3.5:2.5:1:1.2:0.4.

[0052] Example

[0053] Example 1

[0054] A high-toughness skateboard shell, the amount of raw materials added is shown in Table 1.

[0055] A method for preparing a high-toughness skateboard shell includes the following steps:

[0056] The raw materials were first heated to 1470℃ at a rate of 18℃ / min for initial melting, and then heated to 1540℃ and held for 1.5h with continuous stirring to form molten steel. The rare earth pre-alloy prepared in Preparation Example 1 was added at a wire feed rate of 2m / s. After standing for 12min, the mold was preheated to 250℃, and then the molten steel was poured into the mold at a casting temperature of 1430℃ and a casting speed of 6kg / s. After casting, the mixture was allowed to cool naturally to room temperature, demolded, and the billet was then subjected to heat treatment.

[0057] First stage: Place the billet in a heat treatment furnace and start heating from room temperature. When the temperature reaches 600℃, the heating rate is controlled at 5℃ / min. When the temperature exceeds 600℃, the heating rate is adjusted to 10℃ / min, and heating continues to 1070℃. Hold the temperature for 2.5 hours. After the holding time is completed, quickly put the billet into oil for cooling. The oil cooling temperature should be below 200℃, and the cooling rate should be ≥50℃ / s to obtain the quenched billet.

[0058] Second stage: The quenched blank is put back into the heat treatment furnace, argon gas is introduced at a flow rate of 0.4 L / min, and heated to 700℃ at a heating rate of 8℃ / min. It is held at this temperature for 5 hours. After the holding time is completed, it is cooled to 300℃ in the furnace and then taken out and air-cooled to room temperature to obtain the slide plate shell.

[0059] Examples 2-5

[0060] A high-toughness skateboard shell differs from Example 1 in that the amount of raw materials added is different, as shown in Table 1.

[0061] Table 1 Percentage content of each raw material

[0062] raw material Example 1 Example 2 Example 3 Example 4 Example 5 carbon 0.35 0.35 0.35 0.4 0.42 chromium 8.5 8.5 8.5 9.0 9.5 silicon 1.8 1.8 1.8 2.0 2.2 molybdenum 0.8 0.8 0.8 0.9 1.1 nickel 1.5 1.5 1.5 2.0 2.4 vanadium 0.1 0.1 0.1 0.15 0.2 titanium 0.05 0.05 0.05 0.07 0.1 boron 0.001 0.001 0.001 0.002 0.003 Rare earth pre-alloys 0.03 0.05 0.07 0.05 0.05 Iron and unavoidable impurities margin margin margin margin margin

[0063] Examples 6-10

[0064] A high-toughness skateboard shell, which differs from Example 4 in that the rare earth pre-alloy is from a different source. The rare earth pre-alloys in Examples 6-10 were prepared using Preparation Examples 2-6, respectively.

[0065] Comparative Example

[0066] Comparative Example 1

[0067] A high-toughness skateboard shell, which differs from Example 1 in that it does not contain rare earth pre-alloys.

[0068] Comparative Example 2

[0069] A high-toughness skateboard shell, which differs from Example 1 in that no aluminum and magnesium are added to the rare earth pre-alloy.

[0070] Performance testing

[0071] The following performance tests were performed on the skateboard shells in Examples 1-10 and Comparative Examples 1-2:

[0072] Tensile strength: The tensile strength was determined according to ASTM E8 "Metallic materials, tensile test method", and the test results are shown in Table 2.

[0073] Elongation after fracture: The elongation after fracture was determined according to GB / T4161-2007 "Test method for plane strain fracture toughness of metallic materials (KIC)" and the test results are shown in Table 2.

[0074] Fracture toughness: The fracture toughness was determined according to GB / T4161-2007 "Test method for plane strain fracture toughness of metallic materials (KIC test method)", and the test results are shown in Table 2.

[0075] Table 2 Detection Results

[0076] project Tensile strength (MPa) Elongation after fracture (%) Fracture toughness (MPa-m 1 / 2 )]]> Example 1 1923 14.6 81.4 Example 2 1928 15.3 83.7 Example 3 1926 15.2 83.2 Example 4 1930 16.1 84.8 Example 5 1927 15.7 84.4 Example 6 1932 16.8 86.3 Example 7 1930 16.6 86.0 Example 8 1938 17.5 87.9 Example 9 1935 17.2 88.6 Example 10 1941 17.9 89.4 Comparative Example 1 1912 8.4 65.9 Comparative Example 2 1915 11.7 70.2

[0077] As shown in Table 2, the high-toughness sliding plate shell of the present invention, through the synergistic effect between various raw materials, can improve the toughness of the material from multiple dimensions such as grain refinement, grain boundary optimization, microstructure control, and defect suppression. Specifically, the tensile strength of the sliding plate shell is 1923-1941 MPa, the elongation after fracture is 14.6-17.9%, and the fracture toughness is 81.4-89.4 MPa·m. 1 / 2 .

[0078] Combining Example 1 and Comparative Examples 1-2, it can be seen that the tensile strength of the skateboard shell in Example 1 is 1923 MPa, the elongation after fracture is 14.6%, and the fracture toughness is 81.4 MPa·m. 1 / 2 The results are superior to those of Comparative Examples 1-2, indicating that adding rare earth pre-alloys to the raw materials of skateboard shells is more suitable, and adding aluminum and magnesium to rare earth pre-alloys is more suitable. By "rare earth purification and impurity removal + regulation of inclusion morphology + optimization of grain boundaries", and "aluminum and magnesium synergistic effect (enhancing purification, refining grains, and improving rare earth distribution)", the toughness of skateboard shells is improved from three core dimensions: "reducing crack initiation, hindering crack propagation, and improving matrix plasticity".

[0079] As can be seen from Examples 1-5, the tensile strength, elongation after fracture, and fracture toughness of the slide plate shell in Example 4 are better, indicating that the addition amount of each raw material in Example 4 is more appropriate, and the addition amount of rare earth pre-alloy is also more appropriate. If the addition amount of rare earth pre-alloy is too small, the "purification, refinement, and modification" effect of rare earth pre-alloy cannot be fully utilized, and the steel shell still retains the performance defects before modification. The grain refinement is insufficient, making it difficult to meet the requirements of "strength, toughness, and fatigue resistance" for the steel shell of the slide plate brick. If the addition amount of rare earth pre-alloy is too large, it will destroy the microstructure of the steel due to problems such as "grain boundary segregation and brittle phase formation", resulting in a decrease in the toughness of the steel shell and a deterioration in the processing performance.

[0080] As can be seen from Examples 4 and 6-10, the tensile strength, elongation after fracture, and fracture toughness of the skateboard shell in Example 10 are better, indicating that the amount of each raw material added in the rare earth pre-alloy in Example 6 is more appropriate. Through the synergistic effect between the raw materials, the hidden defects inside the material can be eliminated, and the overall crack resistance can be enhanced through microstructure optimization. It is more suitable for the complex working conditions of the skateboard shell, which can significantly reduce the risk of fracture failure, extend the service life, and improve the toughness of the skateboard shell.

[0081] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-toughness skateboard shell, characterized in that: The raw materials include the following weight percentages: carbon 0.35-0.42%, chromium 8.5-9.5%, silicon 1.8-2.2%, molybdenum 0.8-1.1%, nickel 1.5-2.4%, vanadium 0.1-0.2%, titanium 0.05-0.1%, boron 0.001-0.003%, rare earth pre-alloys 0.03-0.07%, with the balance being iron and unavoidable impurities; The rare earth pre-alloy is composed of lanthanum, cerium, yttrium, aluminum and magnesium; The weight ratio of lanthanum, cerium, yttrium, aluminum and magnesium is (3-4):(2-3):1:(0.8-1.2):(0.2-0.4).

2. The high-toughness skateboard shell according to claim 1, characterized in that: The rare earth pre-alloy is prepared by the following method: lanthanum, cerium, yttrium, aluminum and magnesium are melted under an inert gas, kept at a constant temperature, and powdered to obtain pre-alloy powder. The pre-alloy powder is then pressed into alloy wire to obtain the rare earth pre-alloy.

3. The high-toughness skateboard shell according to claim 2, characterized in that: The melting temperature is 850-950℃, the holding time is 30-60min, the molten pre-alloy is powdered by water atomization, the atomization pressure is 8-12MPa, the water temperature is 20-30℃, and the pressure for pressing into alloy wire is 200-300MPa.

4. The high-toughness skateboard shell according to claim 2, characterized in that: The oxygen content of the pre-alloyed powder is ≤0.05wt%, the loose packing density is 2.5-3.0g / cm3, and the density of the alloy wire is ≥96%.

5. A method for preparing a high-toughness skateboard shell as described in any one of claims 1-4, characterized in that: The process includes the following steps: heating the raw materials to a preliminary temperature for initial melting, then continuing to heat and hold the temperature while constantly stirring to form molten steel, adding rare earth pre-alloys, letting it stand, casting it to form a billet, and then subjecting the billet to a two-stage heat treatment to obtain the slide plate shell.

6. The method for preparing a high-toughness skateboard shell according to claim 5, characterized in that: The rare earth pre-alloy is added by wire feeding.

7. The method for preparing a high-toughness skateboard shell according to claim 5, characterized in that: The specific steps of the two-stage heat treatment are as follows: First stage: Place the billet in a heat treatment furnace and start heating from room temperature. When the temperature reaches 600℃, the heating rate is controlled at 4-6℃ / min. When the temperature exceeds 600℃, adjust the heating rate to 8-12℃ / min and continue heating to 1060-1080℃. Hold the temperature for 2-3 hours. After the holding time is completed, quickly put the billet into oil for cooling. Cool the billet to below 200℃. The cooling rate must be ≥50℃ / s to obtain the quenched billet. Second stage: The quenched blank is put back into the heat treatment furnace, and argon gas is introduced at a flow rate of 0.3-0.5 L / min. It is heated to 690-710℃ at a heating rate of 6-10℃ / min and held for 4-6 hours. After the holding is completed, it is cooled to 300℃ in the furnace and then taken out and air-cooled to room temperature to obtain the slide plate shell.