A method of injection molding a strong and tough FeMnAlC alloy

Abstract

The application discloses a kind of methods for preparing FeMnAlC alloy by injection molding, belong to metal powder injection molding process technical field.It includes the following steps: S1, aluminum powder is prepared by gas atomization method, and micro-carbon ferromanganese alloy powder is prepared by mechanical crushing method, and then mixed after adding binder to aluminum powder and micro-carbon ferromanganese alloy powder;S2, mixing, granulation is made into feed;S3, granular feed is heated, and the blank is obtained by injection machine injection, and the binder is removed to obtain the defatted blank;S4, the defatted blank is sintered at 1230-1250 DEG C under protective gas atmosphere, quenched at 1000-1100 DEG C after cooling, heat treated at 500-600 DEG C, and polished to obtain toughened FeMnAlC alloy.The FeMnAlC alloy prepared by the application can solve the problems of high-carbon high-alloy, thin-walled part forming difficulty and uneven structure, and improve the forming efficiency and structure uniformity of FeMnAlC alloy parts.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal powder injection molding process, and more particularly to a method for preparing a toughened FeMnAlC alloy by injection molding. BACKGROUND

[0002] The overall weight of a vehicle directly affects the fuel consumption, and a 10% reduction in weight can increase the fuel efficiency by 7%. Therefore, the lightweight of vehicles and other transportation vehicles is of great significance. In view of the requirements of lightweight and high safety performance of vehicles, it is of great significance to prepare advanced high-strength steel for vehicles with good combination of strength and plasticity.

[0003] Studies have shown that the addition of 1% Al in steel can reduce the density by 0.101 g / cm 3 , i.e. a 1.5% reduction in density; and the addition of 1% C in steel can reduce the density by 0.41 g / cm 3 , i.e. a 5.3% reduction in density. FeMnAlC alloy steel is a lightweight steel developed by increasing the content of Al and C on the basis of high manganese steel, which has the advantages of low density, high strength, high plasticity, corrosion resistance, etc. It has good fatigue performance and good high-temperature oxidation resistance, and at the same time has strong corrosion resistance, wear resistance and high hardness. FeMnAlC alloy steel has excellent comprehensive mechanical properties (yield strength 0.4-1.0 GPa, tensile strength 0.6-1.3 GPa) and significant weight reduction effect. At the same time, FeMnAlC alloy steel also has other excellent properties such as high strength and high toughness at room temperature and low temperature, good fatigue performance and high-temperature oxidation resistance, etc. In addition, the age hardening and energy absorption capacity during collision of FeMnAlC alloy steel make it a high-strength automobile steel with great potential. However, due to the high content of carbon, manganese and aluminum in FeMnAlC alloy steel, plastic deformation is difficult during forming, and the workpiece is prone to cracking, especially thin-walled complex parts are difficult to form. SUMMARY

[0004] In view of the problem that high-carbon high-alloy steel and thin-walled parts are difficult to be formed in the prior injection molding, the application provides a method for preparing a toughened FeMnAlC alloy by injection molding, which is used to solve the problem that high-carbon high-alloy steel and thin-walled parts are difficult to be formed, and meanwhile, the network carbide enriched at the grain boundary of the injection-molded part is eliminated by using the residual heat of the formed part, the distribution of Mn, Al and C elements in the FeMnAlC alloy steel is improved, and the mechanical properties of the FeMnAlC alloy steel material are further improved. The component prepared by the method has no defects such as holes, cracks, pores and slag inclusions, and has small and uniform organization, and the mechanical properties of the formed part are equivalent to those of a hot-rolled or forged part, the material utilization rate and forming efficiency of the FeMnAlC alloy component are high, and the method is a high-efficiency and clean preparation technology.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the application is as follows:

[0006] The application provides a method for preparing a toughened FeMnAlC alloy by injection molding, which comprises the following steps.

[0007] S1, spherical aluminum powder is prepared and sieved by using a gas atomization method, and micro-carbon ferromanganese alloy powder is prepared by using a mechanical crushing method, and then the spherical aluminum powder and the micro-carbon ferromanganese alloy powder are mixed after adding a binder to obtain mixed powder;

[0008] S2, the mixed powder is mixed and then granulated to prepare a feedstock;

[0009] S3, the feedstock is heated to have fluidity, and then the feedstock is injected into a mold cavity by using an injection machine to obtain a blank, the blank is taken out after cooling, and then the binder is removed to obtain a debinding blank;

[0010] S4, the debinding blank is sintered at 1230-1250 DEG C under a protective gas atmosphere, is cooled to 1000-1100 DEG C for quenching, and is heat-treated at 500-600 DEG C after the quenching is completed, and then is polished to obtain a toughened FeMnAlC alloy.

[0011] Preferably, the FeMnAlC alloy is composed of Al: 8-12%, Mn: 20-30%, C: 0.8-2%, and the balance of Fe in terms of mass percentage; and the density of the FeMnAlC powder is 6.3-6.9 g / cm 3 .

[0012] Preferably, in S1, the method for preparing the spherical aluminum powder by using the gas atomization method comprises the following steps:

[0013] Metal aluminum is placed in a powder preparation device and is subjected to pre-vacuum treatment, a protective gas is filled into an atomization chamber as an atomization medium, the metal aluminum is heated and melted, the molten metal aluminum falls and breaks into small metal droplets, and the small metal droplets are gradually spheroidized to obtain spherical aluminum powder which is sieved.

[0014] The protective gas is nitrogen or argon, the atomization temperature is 700-740℃, the gas pressure is set to 0.58-0.62MPa, the diameter of the guide tube is 5.5mm, and the particle size of the spherical aluminum powder is 10-70μm.

[0015] Preferably, in S1, the method for preparing micro-carbon ferromanganese alloy powder by mechanical pulverization includes the following steps:

[0016] The micro-carbon ferromanganese alloy was placed in a sand mill, and water and ethanol were added to form a suspension slurry. After the sand milling was completed, the mixture was cooled to room temperature and then screened to obtain micro-carbon ferromanganese alloy powder.

[0017] The mass concentration of the suspension slurry is 8-12%, the volume ratio of water to ethanol is 8:1, the milling speed is 1200 r / min, and the particle size of the micro-carbon manganese-iron alloy powder is 10-70 μm.

[0018] Preferably, in S1, the amount of adhesive used is 0.1% to 0.5% of the mass of the FeMnAlC alloy;

[0019] The adhesive, by mass percentage, comprises 50-60% paraffin wax, 20-30% polyethylene, and the balance being mineral oil.

[0020] Preferably, in S1, the rotation speed of the sealed mixing is 40-100 r / min, and the time is 2-4 h.

[0021] Preferably, in S2, the mixing temperature is 160°C, the time is 3 hours, the rotation speed is 50 r / min, and the loading of the mixed powder is 50%.

[0022] Preferably, in S3, the heating temperature is greater than 150°C, the injection pressure of the injection machine is 1-4 kPa, the temperature is 150-180°C, and the holding time is 10-70 s.

[0023] Preferably, in step S4, the protective gas is argon, the sintering time is 90 minutes, and the heat treatment time is 10 to 20 hours.

[0024] Preferably, in S4, the grinding is carried out sequentially on sandpaper of #240, #400, #600, #800, #1000, #1200, #1500, and #2000, and then polished with diamond polishing compound.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) This invention utilizes injection molding technology and selects to prepare Al powder by gas atomization and micro carbon manganese iron alloy powder by crushing. Then, FeMnAlC powder is prepared by mixing the two powders through a drum mixer. Finally, FeMnAlC alloy molded parts are prepared. The prepared FeMnAlC alloy steel components have a density ≥99%, a hardness ≥290HB, and a tensile strength ≥700MPa (20℃). They have high density, high hardness, and excellent strength.

[0027] (2) In the FeMnAlC alloy steel component after injection molding, network carbides are prone to appear in the microstructure and accumulate at the grain boundaries, which seriously reduces the mechanical properties of the material. By using the residual heat of the molded part itself to cool it in a certain way, the formation and aggregation of network carbides can be effectively suppressed, the forming efficiency of FeMnAlC alloy parts can be improved, and a fine and uniform microstructure and excellent mechanical properties can be obtained. It is a highly efficient and energy-saving manufacturing method.

[0028] (3) The injection molding method for FeMnAlC alloy provided by the present invention has the advantages of short preparation process and integrated preparation of structure and function of complex geometric components. FeMnAlC alloy molded parts with high hardness, fine structure, complex structure, high strength and good toughness can be successfully prepared by the process method of the present invention.

[0029] (4) When Al powder is prepared by gas atomization, a protective gas is introduced. The molten metal liquid heated at high temperature is subjected to high-speed fluid impact and shearing during the falling process, and is split into small metal droplets. Then, under the action of surface tension, the formed metal droplets gradually become spherical, which meets the requirements for the use of ultrafine particle size powder. When micro carbon manganese iron alloy powder is prepared by crushing, the motor speed is controlled to perform nano-pulverization. After pulverization, the powder is taken out and dried to obtain a product with good dispersibility. Attached Figure Description

[0030] Figure 1 This is a scanning electron microscope image of pure aluminum powder from Example 1 of the present invention;

[0031] Figure 2 This is a scanning electron microscope image of the micro-carbon manganese-iron alloy powder of Example 1 of the present invention;

[0032] Figure 3 The image shows a scanning electron microscope (SEM) image of the FeMnAlC alloy prepared in Example 2 of this invention.

[0033] Figure 4 The image shows a scanning electron microscope (SEM) image of the FeMnAlC alloy prepared in Example 3 of this invention.

[0034] Figure 5 This is a scanning electron microscope image of the FeMnAlC alloy prepared in Example 4 of the present invention;

[0035] Figure 6 A scanning electron microscope image of the FeMnAlC alloy prepared in Example 5 of the present application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0037] In the following examples, the experimental methods are described, and if no special description is given, they are all conventional methods; the reagents and materials can be obtained from commercial channels if no special description is given.

[0038] Example 1

[0039] A method for preparing a toughened FeMnAlC alloy by injection molding, comprising the following steps:

[0040] S1, a method for preparing spherical aluminum powder by gas atomization: small pieces of aluminum metal are placed in a crucible of an atomization powder preparation device, and then pre-vacuum treatment is performed, nitrogen gas is then filled into an atomization chamber below the crucible as an atomization medium, the crucible and the atomization chamber are connected through a flow guide pipe, and the diameter of the flow guide pipe is 5.5 mm. The aluminum metal in the crucible is heated and melted at an atomization temperature of 700 ℃ and a gas pressure of 0.58 MPa, the molten aluminum liquid continuously falls from the bottom of the crucible along the flow guide pipe, and is subjected to high-speed fluid impact shearing when flowing into the atomization chamber, the columnar liquid stream is dispersed into small metal liquid droplets, the liquid droplets gradually spheroidize under the action of surface tension, and continuously cool and solidify as the temperature decreases, so that fine spherical powder can be obtained. The powder obtained by atomization is sieved to obtain spherical aluminum powder with a particle size of 10-70 μm;

[0041] A method for preparing micro-carbon ferromanganese alloy powder by mechanical crushing: the micro-carbon ferromanganese alloy is placed in a sand mill, and a suspension slurry with a mass concentration of 10% is formed after adding water and ethanol (volume ratio 8:1) and then performing cyclic sand milling at a speed of 1200 r / min. After sand milling, the slurry is cooled to room temperature with cold water and then sieved to obtain irregular micro-carbon ferromanganese alloy powder with a particle size of 10-70 μm;

[0042] The prepared spherical aluminum powder, micro-carbon manganese iron alloy powder, wherein the component ratio of Fe:Mn:Al:C is 71.2:20:8:0.8, and 0.5% of an organic binder (the organic binder is composed of 55% paraffin, 25% polyethylene, and the balance of mineral oil) are added into a plastic container for sealing, and then mixed in a drum-type powder mixer at a speed of 80 rpm for 3 h to obtain a mixed powder;

[0043] S2, the mixed powder is transferred to an internal mixer, mixed at 160°C for 3 h at a speed of 50 r / min, and the loading capacity is 57%, and then granulated by a granulator to prepare a feedstock;

[0044] S3, the granular feedstock is heated to above 150°C to have fluidity, and then injected into a mold cavity by an injection machine to obtain a green body with a certain rigidity and a required shape, the temperature of the injection machine is 160°C, the pressure is 2 KPa, the holding time is 30 s, and the injection-molded green body is obtained after being cooled and taken out of the mold. The shaped green body is first removed from part of the binder in dichloromethane solvent, and then the remaining binder is gradually removed from different parts of the compact along the micro-channels between the particles in a debinding furnace, and the debinding time is 6 h to obtain a debound compact. The removal rate of the binder should be slow to avoid defects such as blistering and cracking of the shaped green body;

[0045] S4, the debound compact is placed into a sintering furnace, sintered at 1250°C for 90 min under an argon protective atmosphere to obtain a sintered compact, eliminate the pores between the powder particles, and make the injection part fully dense or close to fully dense; then cooled to 1050°C in an oil pool for quenching, cooled to room temperature, placed into a heating furnace at 550°C for 20 h, then taken out and cooled to room temperature in air, polished on #240, #400, #600, #800, #1000, #1200, #1500, and #2000 sandpaper in turn, and then polished with diamond polishing agent to obtain a strong and tough FeMnAlC alloy.

[0046] Example 2

[0047] A method for preparing a strong and tough FeMnAlC alloy by injection molding, comprising the following steps:

[0048] S1, the method for preparing spherical aluminum powder by gas atomization is the same as that in Example 1;

[0049] The method for preparing micro-carbon manganese iron alloy powder by mechanical crushing is the same as that in Example 1;

[0050] The prepared spherical aluminum powder, micro-carbon manganese iron alloy powder, wherein the component ratio of Fe:Mn:Al:C is 64.8:24:10:1.2, and 0.3% of organic binder (the organic binder is composed of 50% paraffin, 30% polyethylene and the rest of mineral oil) are added into a plastic container for sealing, and then mixed in a drum-type powder mixer at a speed of 100 rpm for 3 h to obtain a mixed powder;

[0051] S2, the mixed powder is transferred to an internal mixer, mixed at 160°C for 3 h at a speed of 50 r / min and a loading capacity of 57%, and then granulated by a granulator to prepare a feedstock;

[0052] S3, the granular feedstock is heated to above 150°C to have fluidity, and then injected into a mold cavity by an injection machine to obtain a green body with a certain rigidity and a required shape, the temperature of the injection machine is 180°C, the pressure is 4 KPa, the holding time is 50 s, and the injection-molded green body is obtained after being taken out of the mold after cooling. The shaped green body is first removed from part of the binder in dichloromethane solvent, and then the remaining binder is gradually removed from different parts of the compact along the micro-channels between the particles in a debinding furnace, and the debinding time is 6 h to obtain a debound compact. The removal rate of the binder should be slow to avoid defects such as blistering and cracking of the shaped green body;

[0053] S4, the debound compact is placed in a sintering furnace, sintered at 1250°C for 90 min under an argon protective atmosphere to obtain a sintered compact, eliminate the pores between the powder particles, and the injection part reaches full densification or near full densification; then cooled to 1050°C in an oil pool, cooled to room temperature, and then placed in a heating furnace at 550°C for 20 h, and then taken out and cooled to room temperature in air, and then polished on #240, #400, #600, #800, #1000, #1200, #1500, #2000 sandpaper, and then polished with diamond polishing agent to obtain a strong and tough FeMnAlC alloy.

[0054] Example 3

[0055] A method for preparing a strong and tough FeMnAlC alloy by injection molding, comprising the following steps:

[0056] S1, the method for preparing spherical aluminum powder by gas atomization is the same as that in Example 1;

[0057] The method for preparing micro-carbon manganese iron alloy powder by mechanical crushing is the same as that in Example 1;

[0058] The prepared spherical aluminum powder, micro-carbon manganese iron alloy powder, wherein the component ratio of Fe:Mn:Al:C is 56:30:12:2, and 0.4% of the organic binder (the organic binder is composed of 60% paraffin, 25% polyethylene and the balance of mineral oil) are added into a plastic container for sealing; then mixed in a drum-type powder mixer at a speed of 100 rpm for 3h to obtain a mixed powder;

[0059] S2, the mixed powder is transferred to an internal mixer, mixed at 160°C for 3h at a speed of 50r / min, and the loading capacity is 57%; then granulated by a granulator to prepare a feedstock;

[0060] S3, the granular feedstock is heated to above 150°C to have fluidity, and then injected into a mold cavity by an injection machine to obtain a green body with a certain rigidity and a required shape, the temperature of the injection machine is 150°C, the pressure is 1KPa, the holding time is 50s, and the injection-molded green body is obtained after being taken out of the mold after cooling; the formed green body is first removed from part of the binder in dichloromethane solvent, and then the remaining binder is gradually removed from different parts of the green body along the micro-channels between the particles in a debinding furnace, and the debinding time is 7h to obtain a debound green body; the removal rate of the binder should be slow to avoid defects such as blistering and cracking of the formed green body;

[0061] S4, the debound green body is placed in a sintering furnace, sintered at 1250°C for 90min under an argon protective atmosphere to obtain a sintered body, eliminate the pores between the powder particles, and make the injection part fully dense or close to full densification; then cooled to 1050°C in an oil pool for quenching, cooled to room temperature, then placed in a heating furnace at 550°C for 20h, then taken out and cooled to room temperature in air, and then polished on #240, #400, #600, #800, #1000, #1200, #1500, and #2000 sandpaper in turn, and then polished with diamond polishing agent to obtain a strong and tough FeMnAlC alloy.

[0062] Example 4

[0063] A method for preparing a strong and tough FeMnAlC alloy by injection molding, comprising the following steps:

[0064] S1, the method for preparing spherical aluminum powder by gas atomization is the same as that in Example 1;

[0065] The method for preparing micro-carbon manganese iron alloy powder by mechanical crushing is the same as that in Example 1;

[0066] The prepared spherical aluminum powder, micro-carbon ferromanganese alloy powder, wherein the component ratio of Fe:Mn:Al:C is 56:30:12:2, and 0.1% of an organic binder (the organic binder is composed of 55% paraffin, 30% polyethylene and the rest of mineral oil) are added into a plastic container for sealing, and then mixed in a drum-type powder mixer at a speed of 40-100 rpm for 3 hours to obtain a mixed powder;

[0067] S2, the mixed powder is transferred to an internal mixer, mixed at 160℃ for 3 hours at a speed of 50 r / min and a loading capacity of 57%, and then granulated by a granulator to prepare a feedstock;

[0068] S3, the granular feedstock is heated to above 150℃ to have fluidity, and then injected into a mold cavity by an injection machine to obtain a green body with a certain rigidity and a required shape, the temperature of the injection machine is 170℃, the pressure is 2KPa, the holding time is 10s, and the injection-molded green body is obtained after being taken out of the mold after cooling; the formed green body is first removed from part of the binder in dichloromethane solvent, and then the remaining binder is gradually removed from different parts of the green body along the micro-channels between the particles in a debinding furnace, the debinding time is 6h, and the debinding green body is obtained; the removal rate of the binder should be slow to avoid defects such as blistering and cracking of the formed green body;

[0069] S4, the debinding green body is placed into a sintering furnace, sintered at 1250℃ for 90min under an argon protective atmosphere to obtain a sintered body, eliminate the pores between the powder particles, and make the injection part fully dense or close to fully dense; then cooled to 1100℃ in an oil pool for quenching, cooled to room temperature, placed into a heating furnace at 600℃ for 10h, then taken out and cooled to room temperature in air, polished on #240, #400, #600, #800, #1000, #1200, #1500, #2000 sandpaper in turn, and then polished with diamond polishing agent to obtain a strong and tough FeMnAlC alloy.

[0070] The spherical Al powder and the micro-carbon ferromanganese alloy powder prepared in Example 1 are observed by an electron microscope for microstructure observation, Figure 1 The scanning electron microscope (SEM) image of the spherical Al powder of Example 1 is shown in Figure 1 The aluminum powder is in the form of spherical particles with a size of 10-70um. Figure 2 The scanning electron microscope (SEM) image of the micro-carbon ferromanganese alloy powder of Example 1 is shown in Figure 2 The micro-carbon ferromanganese alloy powder particles are in the form of irregular particles with a size of 10-70um after screening.

[0071] The strong and tough FeMnAlC alloy prepared in Examples 1-4 is observed by an electron microscope for microstructure observation, Figures 3-6Scanning electron microscope (SEM) images of the strong and tough FeMnAlC alloy prepared in Examples 1-4 of the present application. As shown, the injection-molded FeMnAlC alloy has a microstructure of austenite (light gray), ferrite (gray), and carbide (black) after the strong and tough treatment. The carbide content of the FeMnAlC alloy with a carbon content of 2.0% is higher than that of the FeMnAlC alloy with a carbon content of 1.2%. Figures 3-6

[0072] The strong and tough FeMnAlC alloy prepared in Examples 1-4 was subjected to density measurement and performance test. The prepared sample has a density of 99.2-99.6%, a Brinell hardness HB of 340-420, and a tensile strength of 840-916 MPa, which is superior to that of the FeMnAlC alloy obtained by casting (tensile strength of 724 MPa and Brinell hardness HB of 320). The injection-molded FeMnAlC alloy prepared by the method has excellent tensile strength.

[0073] In summary, the present application prepares FeMnAlC alloy steel powder by injection molding, uniformly mixes aluminum powder, micro-carbon manganese iron powder, and adhesive, injection molds in a heated state by an injection machine, removes the organic binder in the molded blank by chemical and thermal decomposition, obtains a dense product after sintering, and adjusts the microstructure uniformly by a certain heat treatment method. This molding method can quickly manufacture high-performance complex-shaped FeMnAlC alloy steel components, such as body outer structure components, internal structure components, suspension structure components, and support components. This technology solves the problem of easy cracking of FeMnAlC alloy steel components in traditional manufacturing technology. At the same time, it has high molding precision, excellent strength, and good one-piece molding effect, greatly shortens the production cycle, and improves the material utilization rate. Network-shaped carbides easily appear in the microstructure of the FeMnAlC alloy steel material after injection molding, which seriously affects the mechanical properties of the material. Using the residual heat of the molded part for cooling in a certain cooling manner can eliminate the network-shaped carbides, obtain a fine and uniform microstructure, and improve the mechanical properties of the FeMnAlC alloy steel material, further reducing the design cross-sectional area of the component.

[0074] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications without departing from the spirit and scope of the application. Therefore, the appended claims are intended to cover all such changes and modifications that fall within the scope of the application.

[0075] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, if such modifications and changes fall within the scope of the claims and their equivalents, they are intended to be included therein.​

Claims

1. A method for preparing a toughened FeMnAlC alloy by injection molding, characterized in that, Includes the following steps: S1. Spherical aluminum powder is prepared and sieved by gas atomization method, and micro-carbon manganese-iron alloy powder is prepared by mechanical crushing method. After adding binder to spherical aluminum powder and micro-carbon manganese-iron alloy powder, they are sealed and mixed to obtain mixed powder. The method for preparing spherical aluminum powder includes the following steps: Metallic aluminum is placed in an atomizing powder-making device and pre-vacuumed. A protective gas is then introduced into the atomizing chamber as an atomizing medium. The metallic aluminum is heated and melted. The molten metallic aluminum falls and breaks into small metal droplets, which are gradually spherized and then screened to obtain spherical aluminum powder. The protective gas is nitrogen or argon, the atomization temperature is 700~740℃, the gas pressure is set to 0.58~0.62 MPa, the diameter of the guide tube is 5.5 mm, and the particle size of the spherical aluminum powder is 10~70 μm. The method for preparing micro-carbon manganese-iron alloy powder includes the following steps: The micro-carbon ferromanganese alloy was placed in a sand mill, and water and ethanol were added to form a suspension slurry. After the sand milling was completed, the mixture was cooled to room temperature and then screened to obtain micro-carbon ferromanganese alloy powder. The mass concentration of the suspension slurry is 8-12%, the volume ratio of water to ethanol is 8:1, the milling speed is 1200 r / min, and the particle size of the micro-carbon manganese iron alloy powder is 10-70 μm. S2. The mixed powder is kneaded and then granulated to form feed; S3. Heat the feed material until it is fluid, inject it into the mold cavity through an injection molding machine to obtain a preform, remove it after cooling, and remove the adhesive to obtain a degreased preform; The heating temperature is greater than 150℃, the injection pressure of the injection machine is 1~4KPa, the temperature is 150~180℃, and the holding time is 10~70s; S4. The degreased billet is sintered at 1230~1250℃ in a protective gas atmosphere, then quenched at 1000~1100℃. After quenching, it is heat-treated at 500~600℃ and polished to obtain a toughened FeMnAlC alloy. The FeMnAlC alloy, by mass percentage, has the following composition: Al: 8-12%, Mn: 20-30%, C: 0.8-2%, with the balance being Fe; the density of the FeMnAlC alloy is 6.3-6.9 g / cm³. 3 .

2. The method for preparing strong and toughened FeMnAlC alloy by injection molding according to claim 1, characterized in that, In S1, the amount of adhesive used is 0.1~0.5% of the mass of the FeMnAlC alloy; The adhesive, by mass percentage, comprises 50-60% paraffin wax, 20-30% polyethylene, and the balance being mineral oil.

3. The method for preparing strong and toughened FeMnAlC alloy by injection molding according to claim 1, characterized in that, In S1, the rotation speed of the sealed mixing is 40~100 r / min, and the time is 2~4h.

4. The method for preparing strong and toughened FeMnAlC alloy by injection molding according to claim 1, characterized in that, In S2, the mixing temperature is 160℃, the time is 3h, the rotation speed is 50r / min, and the loading of the mixed powder is 50%.

5. The method for preparing strong and toughened FeMnAlC alloy by injection molding according to claim 1, characterized in that, In S4, the protective gas is argon, the sintering time is 90 minutes, and the heat treatment time is 10-20 hours.

6. The method for preparing strong and toughened FeMnAlC alloy by injection molding according to claim 1, characterized in that, In S4, grinding is performed sequentially on sandpaper of #240, #400, #600, #800, #1000, #1200, #1500, and #2000, followed by polishing with diamond polishing compound.

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