Method for preparing high-strength alloy through injection molding

Abstract

The invention discloses a method for preparing a high-strength alloy through injection molding. According to the high-strength and high-hardness Fe-Mn-Al-C alloy, the density is 5.8-7 g / cm < 3 >, the density is 99% or above, the tensile strength is larger than 1200 MPa, and the hardness is larger than 360 HV0.1. The preparation method of the high-strength and high-hardness Fe-Mn-Al-C alloy comprises the following steps: mixing Fe-Mn-Al-C alloy powder with a binder in a vacuum environment at 180-190 DEG C to obtain a feed; adding the feedstock into an injection machine, heating the feedstock until the feedstock has fluidity, and injecting the feedstock into a mold cavity through the injection machine to obtain a green body; and the blank is subjected to degreasing, sintering, solution treatment and aging treatment, and the high-strength and high-hardness Fe-Mn-Al-C alloy is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of metal powder injection molding technology, and in particular to a method for preparing high-strength and high-hardness FeMnAlC alloy parts by injection molding. Background Art

[0002] FeMnAlC steel is a new type of high-strength, low-density steel. It uses Mn and Al to replace expensive Cr and Ni elements and can be used as a substitute for stainless steel. It has significant advantages. The density of FeMnAlC alloy is significantly lower than that of traditional steel. Every 1wt% of Al added can reduce the density by 1.3%, which is crucial for reducing product weight and improving energy efficiency.

[0003] FeMnAlC alloy exhibits excellent mechanical properties and meets the requirements of high-performance structural components. FeMnAlC alloy has good corrosion resistance at both room temperature and high temperature, making it suitable for harsh environments such as aircraft and chemical industries. FeMnAlC alloy also has good fatigue performance, high temperature oxidation resistance, aging hardening ability and collision energy absorption ability, making it a highly promising advanced high-strength steel.

[0004] However, the high content of carbon, manganese and aluminum in FeMnAlC alloy also brings challenges to its preparation process. Traditional preparation processes such as hot rolling and forging have the following problems. It is difficult to accurately control the uniform distribution of alloy components in traditional processes, which easily causes uneven organization and affects the performance of the material.

[0005] In order to overcome the shortcomings of traditional processes, metal injection molding (MIM) technology is considered to be a very promising method for preparing FeMnAlC alloy parts. MIM technology can prepare parts with complex shapes and high dimensional accuracy, and has the advantages of high material utilization and high production efficiency, providing new possibilities for the wide application of FeMnAlC alloys.

[0006] The patent specification with publication number CN113088823A discloses a lightweight, high-strength and high-corrosion-resistant Fe-Mn-Al-C-Cr steel and a preparation method thereof. The lightweight, high-strength and high-corrosion-resistant Fe-Mn-Al-C-Cr steel is composed of the following components in weight percentage: Mn: 25%-35%; Al: 6%-12%; C: 0.7%-2.0%; Cr: 1.0%-6.0%; O: 0.01%-0.5%; Si: 0-0.1%; Ni: 0-0.6%; Cu: 0-0.05%; N: 0-0.05%; trace elements 0-0.1%, trace elements include one or more of V, Co, Mo, P, S; the balance is Fe. The preparation method of the above-mentioned lightweight, high-strength and highly corrosion-resistant Fe-Mn-Al-C-Cr steel includes the following steps: powder raw material preparation, feed preparation, injection, catalysis, sintering, heat treatment, and passivation treatment, wherein the weight ratio of the binder components used in the injection molding feed is: polyoxymethylene: ethylene-vinyl acetate copolymer: polyethylene: microcrystalline wax: stearic acid at a weight ratio of 80-90:1-2:2-3:3-6:1-2, the injection pressure is 60-140MPa, and the sintering atmosphere is an argon atmosphere. This patented technology adds an appropriate amount of Cr and other trace elements, and cooperates with the passivation process to make the obtained Fe-Mn-Al-C-Cr steel have excellent corrosion resistance. However, the patented technical solution does not involve hardness indicators, and the density of Cr-free Fe-Mn-Al-C steel is still as high as 7.68g / cm 3 , it is not lightweight enough, and its mechanical properties such as tensile strength still need to be further improved. Summary of the invention

[0007] In view of the above technical problems and the shortcomings in the art, the present invention provides a lightweight, high-strength and high-hardness Fe-Mn-Al-C alloy with a density of only 5.8 to 7 g / cm 3 , and the density is above 99%. In addition, it has excellent mechanical properties, with a tensile strength greater than 1200MPa and a hardness greater than 360HV 0.1 .

[0008] The invention overcomes the problems in the prior art that high-carbon high-manganese alloys are easy to volatilize and it is difficult to balance the density and mechanical properties of parts, effectively inhibits the volatilization of manganese elements in high-carbon high-manganese alloys, and significantly improves the density, hardness, strength and comprehensive mechanical properties of FeMnAlC alloy parts.

[0009] [1] A high-strength and high-hardness Fe-Mn-Al-C alloy, wherein the composition of the high-strength and high-hardness Fe-Mn-Al-C alloy is, by mass percentage, Al: 7% to 15%, Mn: 28% to 35%, C: 0.9% to 2%, and the balance is Fe; the density of the high-strength and high-hardness Fe-Mn-Al-C alloy is 5.8 to 7 g / cm 3 (e.g. 6.55 g / cm 3 、6.67g / cm 3 、6.75g / cm 3 The density is above 99%, the tensile strength is greater than 1200MPa, and the hardness is greater than 360HV. 0.1 ;

[0010] The preparation method of the high-strength and high-hardness Fe-Mn-Al-C alloy comprises the following steps:

[0011] S1, Fe-Mn-Al-C alloy powder is mixed with a binder in a vacuum environment at 180-190° C. to obtain a feed; the binder is composed of 60%-68% paraffin, 22%-25% polyethylene, and the balance is mineral oil in terms of mass percentage; based on the total mass of the Fe-Mn-Al-C alloy powder and the binder being 100%, the mass percentage of the binder is 0.6%-1%;

[0012] S2, adding the feed material into an injection machine, heating the feed material to have fluidity, and injecting the feed material into a mold cavity through the injection machine to obtain a green body; the injection pressure of the injection machine is 150-200 Bar (for example, 160 Bar, 170 Bar, etc.), and the injection is in a holding pressure state, and the holding pressure is 40-60 Bar, and can further be 40-50 Bar, for example, 45 Bar, etc.;

[0013] S3, degreasing the green body to obtain a degreased green body;

[0014] S4, sintering the debinded blank at 1240-1260° C. in a vacuum environment to obtain a sintered part;

[0015] S5, performing a solution treatment on the sintered part at 1050-1150° C. in a vacuum environment to obtain a solution part;

[0016] S6, subjecting the solid solution product to aging treatment at 480-950° C. in a vacuum environment to obtain the high-strength and high-hardness Fe-Mn-Al-C alloy.

[0017] In the present invention, the vacuum environment of step S1 and steps S4 to S6 is very important. Studies have found that if part or all of the vacuum environment in these steps is replaced by an inert atmosphere such as argon, the strength and hardness of the Fe-Mn-Al-C alloy finally obtained will be significantly reduced.

[0018] Compared with the existing conventional metal injection molding process, the present invention significantly reduces the binder dosage ratio by optimizing the binder formula, and further combines the specific injection pressure and holding pressure of the injection machine to ensure smooth injection molding of the Fe-Mn-Al-C alloy at a low binder dosage ratio, and the Fe-Mn-Al-C alloy obtained in this way has higher density, strength and hardness.

[0019] In some embodiments, in step S1, the mixing speed may be 100-120 rpm, and the mixing time may be 1-3 hours.

[0020] In some embodiments, in step S2, the feed material may be heated to 160-190° C., and the injection machine injection speed may be 20-45 mm / s.

[0021] In some embodiments, in step S3, the degreasing temperature may be 100-200° C., the degreasing time may be 4-12 hours, the degreasing agent may be oxalic acid, and the degreasing atmosphere may be a nitrogen atmosphere.

[0022] In some embodiments, in step S4, the sintering holding time at 1240-1260° C. can be 3-6 hours, preferably 3-4 hours. Under the preferred conditions, the Fe—Mn—Al—C alloy obtained has higher strength and hardness.

[0023] In some embodiments, in step S5, the solution treatment time at 1050-1150° C. can be 3-6 hours, preferably 3-4 hours. Under the preferred conditions, the Fe—Mn—Al—C alloy obtained has higher strength and hardness.

[0024] In some embodiments, in step S6, the aging treatment time at 480-950°C can be 3-6 hours, preferably 3-4 hours. Under the preferred conditions, the Fe-Mn-Al-C alloy obtained has higher strength and hardness.

[0025] In some embodiments, the high-strength and high-hardness Fe-Mn-Al-C alloy has a composition of Al: 8%, Mn: 30%, C: 1%, and the balance Fe, calculated by mass percentage.

[0026] In some embodiments, the high-strength and high-hardness Fe-Mn-Al-C alloy has a composition of Al: 7.18%, Mn: 32.4%, C: 0.96%, and the balance is Fe, calculated by mass percentage.

[0027] In some embodiments, the high-strength and high-hardness Fe-Mn-Al-C alloy has a composition of Al: 9.17%, Mn: 28.54%, C: 1.04%, and the balance Fe, calculated by mass percentage.

[0028] [2] The method for preparing the high-strength and high-hardness Fe-Mn-Al-C alloy according to [1] comprises the following steps:

[0029] S1, Fe-Mn-Al-C alloy powder is mixed with a binder in a vacuum environment at 180-190° C. to obtain a feed; the binder is composed of 60%-68% paraffin, 22%-25% polyethylene, and the balance is mineral oil in terms of mass percentage; based on the total mass of the Fe-Mn-Al-C alloy powder and the binder being 100%, the mass percentage of the binder is 0.6%-1%;

[0030] S2, adding the feed material into an injection machine, heating the feed material until it has fluidity, and injecting the feed material into a mold cavity through the injection machine to obtain a green body; the injection pressure of the injection machine is 150-200 Bar (for example, 160 Bar, 170 Bar, etc.), and the injection is in a holding pressure state, and the holding pressure is 40-60 Bar;

[0031] S3, degreasing the green body to obtain a degreased green body;

[0032] S4, sintering the debinded blank at 1240-1260° C. in a vacuum environment to obtain a sintered part;

[0033] S5, performing a solution treatment on the sintered part at 1050-1150° C. in a vacuum environment to obtain a solution part;

[0034] S6, subjecting the solid solution product to aging treatment at 480-950° C. in a vacuum environment to obtain the high-strength and high-hardness Fe-Mn-Al-C alloy.

[0035] The preparation method described in [3] can refer to the high-strength and high-hardness Fe-Mn-Al-C alloy described in [1] for further selection and optimization of the technical solution.

[0036] Aiming at the problem that injection molded FeMnAlC alloy parts are prone to cracking and have low strength and hardness, the present invention provides a method for preparing Fe-Mn-Al-C alloy based on metal powder injection molding, which is used to solve the problems that injection molded FeMnAlC alloy parts are prone to cracking and have low strength and hardness.

[0037] The present invention also utilizes the super solidus liquid phase sintering technology to determine the optimal sintering temperature of the FeMnAlC alloy powder, ensures the generation and uniform distribution of the liquid phase during the sintering process, promotes the densification of the alloy, improves the density and bonding strength of the parts, and effectively suppresses the occurrence of cracking. By optimizing the sintering process parameters, such as sintering temperature, holding time, etc., the uniformity of the alloy components is promoted, and the Mn, Al, and C elements are evenly distributed in the alloy matrix to avoid the performance degradation caused by local element enrichment. By controlling the carburization reaction during the sintering process, the carbides on the grain boundaries are effectively controlled within the grain boundaries, avoiding grain boundary embrittlement, and improving the strength and toughness of the alloy. After sintering is completed, the parts are subjected to solid solution treatment to eliminate internal stress and further improve the strength and toughness of the alloy. Microscope observation shows that the FeMnAlC alloy parts prepared by the method of the present invention have fine and uniform structure, no obvious holes, cracks, pores, slag inclusions and other defects, and better mechanical properties than conventional injection molded FeMnAlC alloy parts, which proves that the method of the present invention is an efficient and reliable method for preparing high-strength and high-hardness FeMnAlC alloy parts.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention provides a method for preparing high-strength and high-hardness FeMnAlC alloy parts by injection molding. The prepared FeMnAlC alloy steel component has a density of more than 99% and a hardness greater than 360HV 0.1 The tensile strength is greater than 1200MPa (20℃), and it has the advantages of high density, high hardness and high strength.

[0040] 2. The present invention effectively improves the densification degree of the alloy, promotes the homogenization of the alloy composition, and controls the precipitation of grain boundary carbides through super solidus liquid phase sintering and optimized sintering process, thereby significantly improving the strength and hardness of FeMnAlC alloy parts, enabling them to meet higher performance application requirements.

[0041] 3. The present invention uses super solidus liquid phase sintering technology to effectively suppress the generation of cracks during the sintering process, improve the anti-cracking performance of parts, and ensure the yield and reliability of the product.

[0042] 4. The present invention adopts metal powder injection molding technology and adopts a specific binder in combination with injection conditions suitable therefor, and can efficiently and high-quality prepare FeMnAlC alloy parts with complex shapes and precise sizes. It has the advantages of high material utilization, high production efficiency, and low environmental pollution. It has good economic and social benefits. Compared with the existing conventional metal injection molding process, the obtained FeMnAlC alloy parts have higher strength and hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a surface scanning electron microscope (SEM) photograph of the high-strength and high-hardness Fe-Mn-Al-C alloy in Example 1.

[0044] Figure 2 This is the stress-strain curve of the high-strength and high-hardness Fe-Mn-Al-C alloy in Example 1.

[0045] Figure 3 This is a metallographic photograph of the high-strength and high-hardness Fe-Mn-Al-C alloy of Example 2.

[0046] Figure 4 This is the SEM photograph of the fracture of the high-strength and high-hardness Fe-Mn-Al-C alloy of Example 3. DETAILED DESCRIPTION

[0047] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0048] Embodiment 1:

[0049] A method for preparing high-strength and high-hardness FeMnAlC alloy parts by injection molding, comprising the following steps:

[0050] S1. First, put the iron-manganese-aluminum-carbon alloy powder into an internal mixer, wherein the mass ratio of Fe:Mn:Al:C in the iron-manganese-aluminum-carbon alloy powder is 61:30:8:1; turn on the machine and heat it to 185°C, add 1wt% (based on the total mass of the organic binder and the iron-manganese-aluminum-carbon alloy powder as 100%) of an organic binder (the binder composition is 60wt% paraffin, 25wt% polyethylene, and the balance is mineral oil), and then isolate the machine from air, in a vacuum environment, maintain the temperature at 185°C, the speed at 100r / min, the loading amount at 65%, and then start closed mixing for 2.5h to obtain a mixture, which is then made into a feed through a granulator.

[0051] S2. Pour the feed material into the feed port of the injection machine, raise the temperature to 160°C, heat it until it is fluid, and then inject the feed material into the mold cavity at an injection speed of 30 mm / s and an injection pressure of 160 Bar. During injection, it is in a holding pressure state with a holding pressure of 40 Bar and a holding time of 20 seconds, and then an injection blank with a certain supporting force is obtained.

[0052] S3. Place the injection blank into a degreasing furnace, introduce nitrogen, and use 120°C oxalic acid solution to degrease for 8 hours. Cool with the furnace and proceed to the next step of sintering.

[0053] S4. Place the degreased green body into a sintering furnace, maintain a vacuum environment, set the sintering temperature at 1258°C, and sinter for 3 hours. Allow the green body to cool naturally in the furnace, and then take it out.

[0054] S5. Solution process the sintered part at 1050℃ for 3h, maintain vacuum environment, and take it out after cooling in the furnace.

[0055] S6. The solid solution was placed in a vacuum environment, the temperature was set to 480°C, the constant temperature time was 3 hours, and aging treatment was performed. After the aging treatment, it was cooled with the furnace to obtain a high-strength and high-hardness Fe-Mn-Al-C alloy with a density of more than 99% and a density of 6.67g / cm 3 . Figure 1 The surface SEM test results of the high-strength and high-hardness Fe-Mn-Al-C alloy of this embodiment are shown. It can be seen that the microstructure of the alloy is relatively uniform, the precipitated phase morphology is clear, and the distribution is reasonable.

[0056] Table 1 shows the mechanical property test results of the sintered part obtained in step S4 of Example 1, the solid solution part obtained in step S5, and the high-strength and high-hardness Fe-Mn-Al-C alloy obtained in step S6. Figure 2 The stress-strain curve test results of the high-strength and high-hardness Fe-Mn-Al-C alloy of Example 1 are shown.

[0057] Table 1

[0058]

[0059] Embodiment 2:

[0060] A method for preparing high-strength and high-hardness FeMnAlC alloy parts by injection molding, comprising the following steps:

[0061] S1. First, put the iron-manganese-aluminum-carbon alloy powder into an internal mixer, wherein the mass ratio of Fe:Mn:Al:C in the iron-manganese-aluminum-carbon alloy powder is 59.46:32.4:7.18:0.96; turn on the machine and heat it to 185°C, add 0.8wt% (based on the total mass of the organic binder and the iron-manganese-aluminum-carbon alloy powder as 100%) of an organic binder (the binder composition is 65wt% paraffin, 24wt% polyethylene, and the balance is mineral oil), then isolate the machine from air, and in a vacuum environment, maintain the temperature at 185°C, the speed at 100r / min, and the loading amount at 67%, then start closed mixing for 3h to obtain a mixture, which is then made into a feed through a granulator.

[0062] S2. Pour the feed material into the feed port of the injection machine, raise the temperature to 160°C, heat it until it is fluid, and then inject the feed material into the mold cavity at an injection speed of 32mm / s and an injection pressure of 170Bar. During injection, it is in a holding pressure state with a holding pressure of 45Bar and a holding pressure time of 20s, and then obtain an injection blank with a certain supporting force.

[0063] S3. Place the injection blank into a degreasing furnace, introduce nitrogen, and use 120°C oxalic acid solution to degrease for 9 hours. Cool with the furnace and proceed to the next step of sintering.

[0064] S4. Place the degreased green body into a sintering furnace and maintain a vacuum environment. The sintering temperature is 1260°C and the sintering time is 4 hours. The green body is cooled naturally in the furnace and taken out after cooling.

[0065] S5. Solution process the sintered part at 1080℃ for 3h, maintain vacuum environment, and take it out after cooling in the furnace.

[0066] S6. The solid solution was placed in a vacuum environment, the temperature was set to 480°C, the constant temperature time was 3 hours, and aging treatment was performed. After the aging treatment, it was cooled with the furnace to obtain a high-strength and high-hardness Fe-Mn-Al-C alloy with a density of more than 99% and a density of 6.75g / cm 3 , tensile strength is 1258MPa, hardness is 390.6HV 0.1 . Figure 3 The metallographic photographs of the high-strength and high-hardness Fe-Mn-Al-C alloy of this embodiment are shown, indicating that the microstructure of the Fe-Mn-Al-C alloy has a uniform precipitate phase distribution and a good matrix structure, and this microstructure can provide an excellent balance of strength, hardness and toughness.

[0067] Embodiment 3:

[0068] A method for preparing high-strength and high-hardness FeMnAlC alloy parts by injection molding, comprising the following steps:

[0069] S1. First, put the iron-manganese-aluminum-carbon alloy powder into an internal mixer, wherein the mass ratio of Fe:Mn:Al:C in the iron-manganese-aluminum-carbon alloy powder is 61.25:28.54:9.17:1.04; turn on the machine and heat it to 185°C, add 0.6wt% (based on the total mass of the organic binder and the iron-manganese-aluminum-carbon alloy powder as 100%) of an organic binder (the binder composition is 68wt% paraffin, 22wt% polyethylene, and the balance is mineral oil), then isolate the machine from air, and in a vacuum environment, maintain the temperature at 185°C, the speed at 120r / min, the loading amount at 62%, and then start closed mixing for 3h to obtain a mixture, which is then made into a feed through a granulator.

[0070] S2. Pour the feed material into the feed port of the injection machine, heat it to 160°C, heat it until it is fluid, and then inject the feed material into the mold cavity at an injection speed of 30 mm / s and an injection pressure of 160 Bar. During injection, it is in a holding pressure state with a holding pressure of 50 Bar and a holding time of 20 seconds, and then an injection blank with a certain supporting force is obtained.

[0071] S3. Place the injection blank into a degreasing furnace, introduce nitrogen, use 120°C oxalic acid solution to degrease for 4 hours, cool with the furnace, and proceed to the next step of sintering.

[0072] S4. Place the degreased green body into a sintering furnace, maintain a vacuum environment, set the sintering temperature at 1240°C, and the sintering time at 3h. Allow the green body to cool naturally in the furnace, and then take it out.

[0073] S5. Solution process the sintered part at 1050℃ for 4h, maintain vacuum environment, and take it out after cooling in the furnace.

[0074] S6. The solid solution was placed in a vacuum environment, the temperature was set to 480°C, the constant temperature time was 3 hours, and aging treatment was performed. After the aging treatment, it was cooled with the furnace to obtain a high-strength and high-hardness Fe-Mn-Al-C alloy with a density of more than 99% and a density of 6.55g / cm 3 , tensile strength is 1227MPa, hardness is 407.4HV 0.1 . Figure 4 The fracture SEM test results of the high-strength and high-hardness Fe-Mn-Al-C alloy of this embodiment are displayed, indicating that the fracture mechanism of the high-strength and high-hardness Fe-Mn-Al-C alloy is mainly ductile fracture, and it also shows good plasticity and toughness characteristics. The microstructure uniformity of the material is good, and the synergistic effect of the precipitated phase and the matrix plays a strengthening effect in the fracture.

[0075] In summary, the present invention prepares high-strength and high-hardness FeMnAlC alloy by injection molding, effectively inhibits the volatilization of manganese elements in high-carbon and high-manganese alloys, and significantly improves the density, hardness, strength and comprehensive mechanical properties of FeMnAlC alloy parts.

[0076] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A high-strength and high-hardness Fe-Mn-Al-C alloy, characterized in that: The composition of the high-strength and high-hardness Fe-Mn-Al-C alloy is Al: 7% to 15%, Mn: 28% to 35%, C: 0.9% to 2%, and the balance is Fe. The density of the high-strength and high-hardness Fe-Mn-Al-C alloy is 5.8 to 7 g / cm 3 , density is above 99%, tensile strength is greater than 1200MPa, hardness is greater than 360HV 0.1 ; The preparation method of the high-strength and high-hardness Fe-Mn-Al-C alloy comprises the following steps: S1, Fe-Mn-Al-C alloy powder is mixed with a binder in a vacuum environment at 180-190° C. to obtain a feed; the binder is composed of 60%-68% paraffin, 22%-25% polyethylene, and the balance is mineral oil in terms of mass percentage; based on the total mass of the Fe-Mn-Al-C alloy powder and the binder being 100%, the mass percentage of the binder is 0.6%-1%; S2, adding the feed material into an injection machine, heating the feed material until it has fluidity, and injecting the feed material into a mold cavity through the injection machine to obtain a green body; the injection pressure of the injection machine is 150-200 Bar, and the injection is in a holding pressure state, and the holding pressure is 40-60 Bar; S3, degreasing the green body to obtain a degreased green body; S4, sintering the debinded blank at 1240-1260° C. in a vacuum environment to obtain a sintered part; S5, performing a solution treatment on the sintered part at 1050-1150° C. in a vacuum environment to obtain a solution part; S6, subjecting the solid solution product to aging treatment at 480-950° C. in a vacuum environment to obtain the high-strength and high-hardness Fe-Mn-Al-C alloy.

2. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S1, the mixing speed is 100-120 rpm, and the mixing time is 1-3 hours.

3. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S2, the feed material is heated to 160-190°C, and the injection speed of the injection machine is 20-45 mm / s.

4. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S3, the degreasing temperature is 100-200° C., the degreasing time is 4-12 hours, the degreasing agent is oxalic acid, and the degreasing atmosphere is nitrogen atmosphere.

5. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S4, the sintering holding time at 1240-1260° C. is 3-6 hours, preferably 3-4 hours.

6. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S5, the solution treatment time at 1050-1150°C is 3-6 hours, preferably 3-4 hours.

7. The high-strength and high-hardness Fe-Mn-Al-C alloy according to claim 1, characterized in that: In step S6, the aging treatment time at 480-950°C is 3-6 hours, preferably 3-4 hours.

8. The method for preparing a high-strength and high-hardness Fe-Mn-Al-C alloy according to any one of claims 1 to 7, characterized in that: Includes steps: S1, Fe-Mn-Al-C alloy powder is mixed with a binder in a vacuum environment at 180-190° C. to obtain a feed; the binder is composed of 60%-68% paraffin, 22%-25% polyethylene, and the balance is mineral oil in terms of mass percentage; based on the total mass of the Fe-Mn-Al-C alloy powder and the binder being 100%, the mass percentage of the binder is 0.6%-1%; S2, adding the feed material into an injection machine, heating the feed material until it has fluidity, and injecting the feed material into a mold cavity through the injection machine to obtain a green body; the injection pressure of the injection machine is 150-200 Bar, and the injection is in a holding pressure state, and the holding pressure is 40-60 Bar; S3, degreasing the green body to obtain a degreased green body; S4, sintering the debinded blank at 1240-1260° C. in a vacuum environment to obtain a sintered part; S5, performing a solution treatment on the sintered part at 1050-1150° C. in a vacuum environment to obtain a solution part; S6, subjecting the solid solution product to aging treatment at 480-950° C. in a vacuum environment to obtain the high-strength and high-hardness Fe-Mn-Al-C alloy.

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