Cavitation-erosion-resistant low-density steel and preparation method thereof

Abstract

The invention relates to the technical field of metal materials, in particular to cavitation-erosion-resistant low-density steel and a preparation method thereof.The cavitation-erosion-resistant low-density steel is prepared from, by mass, 24.5% of Mn, 0.86% of C, 10-13% of Al and the balance Fe, the total percentage is 100%, the surface layer of the Fe-Mn-Al-C steel treated through the method becomes more compact, and the surface hardness and strength are both greatly improved. In addition, after being treated by the method, the Fe-Mn-Al-C steel surface structure is more uniform, the cavitation erosion resistance, wear resistance, corrosion resistance and other properties are obviously improved, and the requirements of harsh service conditions are met.

Description

Technical Field

[0001] The invention relates to the technical field of metal materials, and in particular to a cavitation-resistant low-density steel and a preparation method thereof. Background Art

[0002] In recent years, low-density steel has again aroused widespread interest. Studies have shown that as long as the density of steel is reduced by 10%, its advantages and competitiveness in the automotive field can be maintained or greatly improved. But at the same time, the automotive industry has put forward higher requirements for the specific strength, formability, connectivity, etc. of materials. Adding light elements such as silicon, aluminum, and magnesium to steel can reduce its density. Light elements also have a significant impact on the thermodynamic stability of steel materials. It can be seen that low-density steel is an emerging discipline, and its research is both an opportunity and a challenge. Therefore, it is necessary and meaningful to conduct systematic research on the basic issues and application practices of low-density steel research in a timely manner.

[0003] Fe-Mn-Al-C low-density steel is a new type of lightweight alloy. Compared with ordinary steels, it contains more Al and Mn elements. Based on the current research on low-density steel, Fe-Mn-Al-C low-density steel with high Al content has excellent weight reduction potential, high strength-plasticity product, strain hardening and high absorption energy, and is one of the most promising lightweight steels. Fe-Mn-Al-C low-density steel has great application potential in flow-through parts such as turbine blades and valve stems due to its light weight, high strength, and certain corrosion resistance. However, it needs to face the invasion of cavitation damage during service, which reduces the service life of the steel. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a cavitation-resistant low-density steel and a preparation method thereof. The present invention adjusts the Al content in the low-density steel to make the surface structure of the Fe-Mn-Al-C steel more uniform, and the cavitation resistance, wear resistance and corrosion resistance are significantly improved, so as to meet the requirements of harsh service conditions.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The invention discloses a cavitation-resistant low-density steel, which is made of the following components by mass percentage: 24.5% Mn, 0.86% C, 10% to 13% Al, the balance Fe, and 100% alloy.

[0007] The cavitation-resistant low-density steel of the present invention regulates the Al content in the steel to be 10% to 13%. When the Al content in the steel exceeds 10%, a ferrite structure appears in the structure. This is because the Al element, as an α-phase stabilizing element, increases the precipitation temperature of ferrite, prompting the generation of more ferrite. The increase in ferrite can increase the strength and hardness of the alloy steel, and make the alloy steel have the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance, excellent stress corrosion resistance, etc., and can be used to manufacture parts resistant to corrosion by the atmosphere, water vapor, water and oxidizing acids. When the Al content in the steel exceeds 13%, there is too much ferrite in the structure, which will increase the brittleness and greatly reduce the strength and toughness, affecting the service life of the material.

[0008] In a preferred embodiment of the present invention, the steel sheet is made of the following ingredients, calculated by mass percentage: Mn 24.5%, C 0.86%, Al content of 10.28% to 12.18%, and Fe balance, which totals 100%.

[0009] In a preferred embodiment of the present invention, the phase composition of the cavitation-resistant low-density steel is austenite and ferrite.

[0010] In a preferred embodiment of the present invention, the density of the cavitation-resistant low-density steel is 6.36-6.55 g / cm 3 .

[0011] In a preferred embodiment of the present invention, the cavitation-resistant low-density hardness is 357.8 to 392.1 HV.

[0012] Another object of the present invention is to provide a method for preparing the cavitation-resistant low-density steel as described in any one of the above, comprising the following steps:

[0013] The following raw materials are weighed according to mass percentage: Mn 24.5%, C 0.86%, Al 10-13%, Fe balance, totaling 100%.

[0014] The raw materials are smelted by vacuum smelting to obtain the smelted alloy. In order to reduce the high-temperature burnout rate of the alloy element Al during the smelting process, a CaO crucible is mainly used for smelting.

[0015] The smelted alloy is forged to obtain a casting.

[0016] The ingot is heat treated to obtain cavitation-resistant low-density steel.

[0017] In a preferred embodiment of the present invention, the forging temperature is 1000° C. to 1100° C., and the average forging ratio is 1.18.

[0018] In a preferred embodiment of the present invention, the heat treatment temperature is 1100-1200° C. and the heat treatment time is 2 hours.

[0019] In a preferred embodiment of the present invention, the melting temperature is 1150° C. and the holding time is 2 h.

[0020] In a preferred embodiment of the present invention, the crucible used in the smelting process is a CaO crucible.

[0021] The processing technology of Fe-Mn-Al-C steel still needs extensive and in-depth research to provide effective parameters for actual industrial applications. It is of great significance to control the phase composition by controlling the Al element content to achieve the enhancement and toughness of Fe-Mn-Al-C low-density steel and improve the actual application performance.

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

[0023] 1. The Fe-Mn-Al-C cavitation-resistant low-density steel prepared by the present invention has an Al content in the steel of 10-13%. When the Al content in the steel exceeds 10%, a ferrite structure appears in the structure. This is because the Al element, as an α-phase stabilizing element, increases the precipitation temperature of ferrite and promotes the production of more ferrite. The increase in ferrite can increase the strength and hardness of the alloy steel, and make the alloy steel have the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance, excellent stress corrosion resistance, etc., and can be used to manufacture parts resistant to corrosion by the atmosphere, water vapor, water and oxidizing acids. When the Al content in the steel exceeds 13%, there is too much ferrite in the structure, which will increase the brittleness and greatly reduce the strength and toughness, affecting the service life of the material.

[0024] 2. The surface layer of the Fe-Mn-Al-C steel obtained by regulating the Al content in the low-density steel in the present invention becomes denser, and the surface hardness and strength are greatly improved. In addition, the surface structure of the Fe-Mn-Al-C steel can be made more uniform, and the cavitation resistance, wear resistance, corrosion resistance and other properties are significantly improved, so as to meet the requirements of harsh service conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a process flow chart of the preparation process.

[0026] Figure 2 1 is the XRD diagram of the Fe-Mn-Al-C low-density steel with different Al contents in the present invention.

[0027] Figure 3 This is a SEM image of the low-density steel prepared in Comparative Example 1 of the present invention after cavitation.

[0028] Figure 4 This is a SEM image of the low-density steel after cavitation prepared in Comparative Example 2 of the present invention.

[0029] Figure 5This is a SEM image of the low-density steel after cavitation prepared in Example 1 of the present invention.

[0030] Figure 6 This is a SEM image of the low-density steel prepared in Example 2 of the present invention after cavitation. DETAILED DESCRIPTION

[0031] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0033] Example 1

[0034] A method for preparing Fe-Mn-Al-C cavitation-resistant low-density steel comprises the following steps:

[0035] (1) The following raw materials are weighed in percentage by mass: Mn 24.5%, C 0.86%, Al 10.28%, Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0036] (2) The smelted alloy is processed by a forging machine at a forging temperature of 1050°C and an average forging ratio of 1.18 to obtain the required ingot.

[0037] (3) The ingot was homogenized at 1150° C. for 2 hours to obtain Fe-Mn-Al-C cavitation-resistant low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments. The preparation process flow chart is shown in FIG. Figure 1 shown.

[0038] Example 2

[0039] A method for preparing Fe-Mn-Al-C cavitation-resistant low-density steel comprises the following steps:

[0040] (1) The following raw materials are weighed in percentage by mass: Mn 24.5%, C 0.86%, Al 12.18%, Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0041] (2) The smelted alloy is processed by a forging machine at a forging temperature of 1050°C and an average forging ratio of 1.18 to obtain the required ingot.

[0042] (3) The ingot was homogenized under heat treatment conditions at about 1150°C for 2 hours to obtain Fe-Mn-Al-C cavitation-resistant low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments.

[0043] Example 3

[0044] A method for preparing Fe-Mn-Al-C cavitation-resistant low-density steel comprises the following steps:

[0045] (1) The following raw materials are weighed in percentage by mass: Mn 24.5%, C 0.86%, Al 10%, Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0046] (2) The smelted alloy is processed by a forging machine at a forging temperature of 1000°C and an average forging ratio of 1.18 to obtain the required ingot.

[0047] (3) The ingot was homogenized at 1100°C for 2 hours to obtain Fe-Mn-Al-C cavitation-resistant low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments.

[0048] Example 4

[0049] A method for preparing Fe-Mn-Al-C cavitation-resistant low-density steel comprises the following steps:

[0050] (1) The following raw materials are weighed in percentage by mass: Mn 24.5%, C 0.86%, Al 13%, Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0051] (2) The smelted alloy is processed by a forging machine at a forging temperature range of 1100°C and an average forging ratio of 1.18 to obtain the required ingot.

[0052] (3) The ingot was homogenized at 1200°C for 2 hours to obtain Fe-Mn-Al-C cavitation-resistant low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments.

[0053] Comparative Example 1

[0054] A method for preparing Fe-Mn-Al-C low-density steel comprises the following steps:

[0055] (1) The following raw materials are weighed in percentage by mass: Mn 24.68%, C 0.83%, Al 6.43%, and Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0056] (2) The smelted alloy is processed by a forging machine at a forging temperature range of 1050°C and an average forging ratio of 1.18 to obtain the required ingot.

[0057] (3) The ingot was homogenized at 1150°C for 2 hours to obtain Fe-Mn-Al-C low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments.

[0058] Comparative Example 2

[0059] A method for preparing Fe-Mn-Al-C low-density steel comprises the following steps:

[0060] (1) The following raw materials are weighed in percentage by mass: Mn 24.44%, C 0.85%, Al 8.44%, Fe balance, totaling 100%; the raw materials used are high-purity metal blocks and carbon powder, and the above raw materials are smelted by a vacuum smelting method at a smelting temperature of 1150° C. and a holding time of 2 h to obtain a smelted alloy. During the smelting process, in order to reduce the high-temperature burnout rate of the alloy element Al, a CaO crucible is mainly used for smelting.

[0061] (2) The smelted alloy is processed by a forging machine at a forging temperature range of 1050°C and an average forging ratio of 1.18 to obtain the required ingot.

[0062] (3) The ingot was homogenized at a heat treatment condition of about 1150°C for 2 hours to obtain Fe-Mn-Al-C low-density steel. After forging, the size of the steel was 120 mm x 120 mm x 60 mm. The ingot was then hot-rolled into a bar for subsequent experiments.

[0063] Experimental process design

[0064] Designing alloying compositions

[0065] Fe-Mn-Al-C steel can be divided into four categories: (1) ferrite low-density steel, (2) ferrite-based dual-phase low-density steel, (3) austenite low-density steel, and (4) austenite-based dual-phase low-density steel. Because the mechanical properties of austenite low-density steel are relatively optimal, the chemical composition range limited by austenite Fe-Mn-Al-C low-density steel is used as the basis, and in order to reduce the density as much as possible to design Fe-Mn-Al-C low-density steel with light weight, high strength and good plasticity, the chemical composition of the alloy steel is formulated as shown in Table 1 below.

[0066] Table 1 Chemical composition of alloy steel

[0067] C (wt.%) Mn (wt.%) Al(wt.%) Fe(wt.%) Comparative Example 1 0.83 24.68 6.43 Bal. Comparative Example 2 0.85 24.44 8.44 Bal. Example 1 0.86 24.50 10.28 Bal. Example 2 0.86 24.50 12.18 Bal.

[0068] The Al element composition in the austenitic Fe-Mn-Al-C light alloy steel used for the initial calculation ranges from Al: 6 to 13 wt.%, wherein the Al element is an α-phase stabilizing element.

[0069] X-ray diffraction test

[0070] The phase composition of Fe-Mn-Al-C low-density steel with different Al contents was obtained through X-ray diffraction testing.

[0071] Optimizing alloy chemistry

[0072] Based on the X-ray diffraction results, we get Figure 2XRD patterns of Fe-Mn-Al-C low-density steels with different Al contents are shown in Table 2 and the phase composition.

[0073] Table 2 Phase composition of Fe-Mn-Al-C low-density steel with different Al contents

[0074] Al(wt.%) Phase composition Comparative Example 1 6.43 Austenite Comparative Example 2 8.44 Austenite Example 1 10.28 Austenite and Ferrite Example 2 12.18 Austenite and Ferrite

[0075] From the results in Table 2 above, it can be seen that when the Al content exceeds 10%, ferrite appears in the structure. This is because Al, as an α-phase stabilizing element, increases the precipitation temperature of ferrite and promotes the production of more ferrite. The increase in ferrite can increase the strength and hardness of the alloy steel, making the alloy steel have the characteristics of high thermal conductivity, low expansion coefficient, good oxidation resistance, excellent stress corrosion resistance, etc., and can be used to manufacture parts resistant to corrosion by the atmosphere, water vapor, water and oxidizing acids.

[0076] Therefore, based on the analysis results of Table 2 above, by adjusting and optimizing the content of micro-alloying elements in the alloy, the value range of the adjusted Al element composition is determined to be: 10-13wt.%, and finally the chemical composition of the optimized alloy shown in Table 3 below is obtained.

[0077] Table 3 Chemical composition of optimized alloy steel

[0078] C (wt.%) Mn (wt.%) Al(wt.%) Fe(wt.%) Comparative Example 1 0.83 24.68 6.43 Bal. Comparative Example 2 0.85 24.44 8.44 Bal. Example 1 0.86 24.50 10.28 Bal. Example 2 0.86 24.50 12.18 Bal.

[0079] Detection of cavitation performance and mechanical properties

[0080] 1. Cavitation resistance

[0081] The present invention conducts cavitation experiments on the Fe-Mn-Al-C light alloy steel prepared in the above-mentioned Examples 1-2 and Comparative Examples 1-2, and the test results are shown in Table 4 below.

[0082] Table 4 Cavitation test results of samples prepared in Examples 1-2 and Comparative Examples 1-2

[0083]

[0084] The cavitation experiment of the present invention is carried out by following steps:

[0085] The cavitation equipment is an XOQS-1000 ultrasonic material cavitation test machine. The horn vibration head of the equipment is 2mm away from the sample, and the ultrasonic frequency is 20kHz. The experimental temperature is controlled at 25±2℃ by a XODC-100F high-precision low-temperature circulator. The cavitation time is 9 hours in total. The FA2004 electronic balance with a precision of 0.1mg is used to weigh the alloy before the start of cavitation, 0.5h, 1h, 1.5h, 2.5h, 3.5h, 4.5h, 5.5h, 6.5h, 7.5h, and 9h, respectively. The cumulative mass loss is recorded to obtain the cavitation rate of the alloy during the cavitation process.

[0086] According to the test results in Table 1, the total cavitation mass loss of the sample prepared in Comparative Example 1 is 15.2 mg, and the cavitation rate is 1.69 mg / h; the total cavitation mass loss of the sample prepared in Comparative Example 2 is 8.0 mg, and the cavitation rate is 0.89 mg / h; while the total cavitation mass loss of the sample prepared in Example 1 is 6.1 mg, and the cavitation rate is 0.68 mg / h; the total cavitation mass loss of the sample in Example 2 is 5.0 mg, and the cavitation rate is 0.56 mg / h; it can be seen that the total cavitation mass loss of Examples 1 and 2 is significantly less than that of Comparative Examples 1 and 2, indicating that after being treated by the method of the present invention, the cavitation resistance of Fe-Mn-Al-C low-density steel can be significantly improved.

[0087] Moreover, the total mass loss and cavitation rate of the samples prepared in Example 1 and Example 2 are similar. This may be because after the treatment of the present invention, ferrite appears in the Fe-Mn-Al-C low-density steel, which makes the grain size of the surface structure smaller and the grain boundaries more, so that the hardness and strength of the Fe-Mn-Al-C low-density steel material are improved, thereby reducing the mass loss rate and improving the cavitation resistance of the Fe-Mn-Al-C low-density steel.

[0088] It can be seen from the test results of Example 1 and Comparative Example 1 that, relative to Example 1, the total cavitation mass loss and cavitation rate of the sample prepared in Comparative Example 1 increased, the mass loss rate was relatively gentle, and the mass loss increased with time and continued until the end of the cavitation experiment, which indicates that the increase in Al content can significantly improve the cavitation resistance of Fe-Mn-Al-C low-density steel.

[0089] In summary, the treatment method of the present invention can significantly improve the cavitation corrosion resistance of Fe-Mn-Al-C low-density steel, and the key factor for the present invention to improve the cavitation corrosion resistance of Fe-Mn-Al-C low-density steel lies in the regulation of the Al element content. When the Al element content is lower than or higher than the parameter range of the present invention, the cavitation corrosion resistance of Fe-Mn-Al-C low-density steel cannot be effectively improved.

[0090] 2. Alloy surface morphology after cavitation

[0091] The samples prepared in Example 1-2 and Comparative Example 1-2 were respectively subjected to scanning electron microscope (SEM) tests, and the test results are as follows: Figure 2-5 shown.

[0092] Figure 3 This is the SEM image of the sample prepared in Comparative Example 1 after cavitation. It can be seen that there is only austenite structure on the surface of the sample, the surface damage is very serious, and the cavitation occurs mainly at the grain boundary, and the cavitation progresses gradually from the grain boundary to the interior of the grain. Figure 4 This is the SEM image of the sample prepared in Comparative Example 2 after cavitation. It can be seen that, similar to Comparative Example 1, the cavitation mechanism of the sample is that plastic deformation begins at the austenite grain boundary and grain boundary spalling occurs. Figure 5 This is the SEM image of the sample prepared in Example 1 after cavitation. Figure 6 The SEM image of the sample prepared in Example 2 after cavitation erosion shows that, relative to Comparative Example 1, the samples prepared in Example 1 and Example 2 clearly show ferrite structure, and have less surface damage, which is mainly concentrated at the austenite grain boundaries, indicating that ferrite has better cavitation resistance than austenite, and further illustrates that the increase in Al content plays an important role in improving the cavitation resistance of Fe-Mn-Al-C low-density steel.

[0093] 3. Mechanical properties test

[0094] The present invention tests the mechanical properties of the Fe-Mn-Al-C low-density steel prepared in Example 1-2 and Comparative Example 1-2, and the test results are shown in Table 5.

[0095] Table 5 Mechanical properties of Fe-Mn-Al-C low-density steel prepared in Example 1-2 and Comparative Example 1-2

[0096]

[0097]

[0098] It can be seen from Table 5 that the hardness of the Fe-Mn-Al-C low-density steel obtained in Example 1 and Example 2 is significantly greater than that in Comparative Example 1 and Comparative Example 2, while the density is less than that in Comparative Example 1 and Comparative Example 2, which indicates that the treatment method of the present invention can effectively improve the hardness of the Fe-Mn-Al-C low-density steel, thereby improving the cavitation corrosion resistance of the Fe-Mn-Al-C low-density steel.

[0099] In summary, the surface layer of the Fe-Mn-Al-C steel treated by the method of the present invention becomes more dense, and the surface hardness and strength are greatly improved. In addition, after being treated by the method of the present invention, the surface structure of the Fe-Mn-Al-C steel can be made more uniform, and the cavitation resistance, wear resistance, corrosion resistance and other properties are significantly improved, so as to meet the requirements of harsh service conditions.

[0100] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0101] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A cavitation-resistant low-density steel, characterized in that: The steel is made of the following ingredients by mass percentage: Mn 24.5%, C 0.86%, Al 10%-13%, and Fe balance, which totals 100%.

2. The cavitation-resistant low-density steel according to claim 1, characterized in that: The invention is made of the following ingredients by mass percentage: Mn 24.5%, C 0.86%, Al content of 10.28% to 12.18%, and Fe balance, which is 100% in total.

3. The cavitation-resistant low-density steel according to claim 1, characterized in that: The phase composition of the cavitation-resistant low-density steel is austenite and ferrite.

4. The cavitation-resistant low-density steel according to claim 1, characterized in that: The density of the cavitation-resistant low-density steel is 6.36-6.55 g / cm 3 .

5. A method for preparing the cavitation-resistant low-density steel according to any one of claims 1 to 4, characterized in that: The following steps are involved: Weigh the following raw materials by mass percentage: Mn 24.5%, C 0.86%, Al 10%-13%, Fe balance, totaling 100%; The raw materials are melted by vacuum smelting to obtain a melted alloy; The smelted alloy is forged to obtain a casting billet; The ingot is heat treated to obtain cavitation-resistant low-density steel.

6. The method for preparing cavitation-resistant low-density steel according to claim 5, characterized in that: The forging temperature is 1000℃~1100℃, and the average forging ratio is 1.

18.

7. The method for preparing cavitation-resistant low-density steel according to claim 5, characterized in that: The heat treatment temperature is 1100°C to 1200°C, and the heat treatment time is 2 hours.

8. The method for preparing cavitation-resistant low-density steel according to claim 5, characterized in that: The melting temperature is 1150°C and the holding time is 2 hours.

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