A molybdenum-containing heat-conducting austenitic manganese steel and a preparation method thereof

Abstract

The present invention discloses a molybdenum-containing heat-conducting austenitic manganese steel and a preparation method thereof, which relates to the technical field of molybdenum-containing manganese steel and comprises the following processes: mixing pig iron and pure iron and melting them; adding ferrochrome, ferromanganese, ferromolybdenum, ferrotitanium, ferroniobium and chromium nitride, and continuing to melt to form molten steel; discharging the furnace and casting to obtain a blank; and performing heat treatment to obtain austenitic manganese steel. By adding element molybdenum to the manganese steel, carbides are formed with carbon in the manganese steel and are dispersed in the steel, which can optimize the morphology and distribution of carbides in the austenitic manganese steel, reduce defects in the manganese steel, and inhibit dislocation movement, which helps to improve the thermal conductivity of the manganese steel; at the same time, solute atoms around it are depleted, which can further improve its thermal conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of molybdenum-containing manganese steel, and specifically relates to a heat-conducting austenitic manganese steel containing molybdenum element and a preparation method thereof. Background Art

[0002] Manganese steel is a high-strength steel, and its main characteristics are its high strength, high hardness and good wear resistance. As a traditional wear-resistant steel, in resisting abrasive wear or chiseling wear under strong impact and high stress, its wear resistance is unparalleled by other materials. In addition, manganese steel also has good toughness and corrosion resistance, showing good tensile strength, impact resistance and wear resistance, and is suitable for various high-strength working environments. Due to its high strength and wear resistance, manganese steel performs excellently in these fields and can withstand large pressures and wear. The application fields of manganese steel are very wide and are often used in manufacturing mechanical parts, automobile parts, railway vehicles, bridges, excavators, loaders and other equipment. However, with the increase of manganese content, the thermal conductivity of manganese steel drops sharply, and its heat conduction is poor; the linear expansion coefficient rises, and large internal stresses will be formed during rapid heating or cooling, increasing the cracking tendency of parts; and it is not easy to conduct heat during processing, and thermal deformation is likely to occur, which is not conducive to the hot processing of manganese steel. Therefore, we propose a heat-conducting austenitic manganese steel containing molybdenum element and a preparation method thereof. Summary of the Invention

[0003] The purpose of the present invention is to provide a heat-conducting austenitic manganese steel containing molybdenum element and a preparation method thereof to solve the problems raised in the above background art.

[0004] To solve the above technical problems, the present invention provides the following technical solutions: A preparation method of a heat-conducting austenitic containing molybdenum element, including the following processes:

[0005] Mix pig iron and pure iron and melt them; add ferrochrome, ferromanganese, ferromolybdenum, ferro-titanium, ferro-niobium and chromium nitride, and continue melting to form molten steel; pour and cast to obtain a blank; perform heat treatment to obtain austenitic manganese steel.

[0006] Further, the austenitic manganese steel includes the following mass components: carbon (C): 1.2 - 1.5%, manganese (Mn): 6 - 9%, molybdenum (Mo): 1 - 2%, chromium (Cr): 2 - 4%, silicon (Si): 0.8 - 1.0%, nitrogen (N): 0.1 - 0.5%, titanium (Ti): 0.06 - 0.10%, niobium (Nb): 0.05 - 0.07%, phosphorus (P) ≤ 0.07%, sulfur (S) ≤ 0.04%, and the balance is iron (Fe).

[0007] Further, the melting temperature is 1420 - 1480 °C.

[0008] Furthermore, the addition temperature of chromium nitride is 1550 - 1570 °C, and then continue smelting for 40 - 60 min.

[0009] Furthermore, the tapping temperature is 1520 - 1550 °C, and the pouring temperature is 1370 - 1420 °C.

[0010] Furthermore, the process conditions of heat treatment are: heating to 1080 - 1130 °C and holding for 90 - 100 min.

[0011] Furthermore, the heat treatment process is as follows: first, heat up at a heating rate of 50 - 100 °C / h to 650 - 700 °C and hold for 1 - 3 h; then heat up at a heating rate of 100 - 150 °C / h to 1050 - 1110 °C and hold for 90 - 100 min; then water-cool, the water temperature is 10 - 20 °C, and the water temperature after water-cooling ≤ 45 °C. The austenite transformation occurs in the manganese steel structure, and its toughness is improved.

[0012] In the above technical solution, chromium (Cr) in the manganese steel can combine with the element carbon in the steel to form hard carbides, thereby improving the hardness and wear resistance of the manganese steel, making it more suitable for various working conditions. And chromium can form a dense oxide film on the surface of the steel, preventing the direct contact of oxygen and moisture with the steel matrix, thereby improving the corrosion resistance of the manganese steel, enabling it to have good applications in humid and corrosive environments.

[0013] The element molybdenum (Mo) is a strong carbide-forming element, which can form carbides with the carbon in the manganese steel and disperse in the steel. It can optimize the morphology and distribution of carbides in austenitic manganese steel, reduce the defects in the manganese steel, inhibit dislocation movement, which helps to improve the thermal conductivity of the manganese steel; at the same time, the solute atoms around it are depleted, which can further improve its thermal conductivity. The carbides of molybdenum have high melting points and hardness, and can fix other carbides in the manganese steel to a certain extent, inhibit the aggregation of cementite, promote the carbides to disperse in small sizes, strengthen the austenite structure of the manganese steel, improve its hardness and strength, which helps to improve the wear resistance of the manganese steel and reduce its damage under friction and wear. It has good thermal stability, mechanical stability and corrosion resistance. At high temperatures, the molybdenum element can form a stable solid solution with iron, thereby improving the high-temperature strength and plasticity of the manganese steel and improving its thermal performance. However, if the content of molybdenum in the manganese steel is too high, it will dissolve in the steel matrix after heat treatment. Due to the large size difference between it and iron atoms, it will generate a large lattice potential, cause lattice distortion, the grain boundary strengthening effect and the impact toughness will decrease; the scattering effect on electrons is enhanced, the thermal conductivity decreases, which is not conducive to the comprehensive performance of the manganese steel.

[0014] The addition of elemental silicon can refine the grains, improving the strength, hardness and wear resistance of manganese steel; and can also improve its thermal stability and oxidation resistance. A small amount of elemental nitrogen mainly exists in the form of nitrides in manganese steel, which can increase the hardness and strength of the steel, improve its wear resistance and corrosion resistance, making it more adaptable to various working conditions; and can also improve its plasticity and toughness, enhancing the impact resistance of manganese steel. However, excessive nitrogen will cause a decrease in the plasticity and toughness of the steel, prone to brittle fracture. Niobium can exist in the form of carbides in the billet, improving its hardness, strength and toughness; after heat treatment, it partially dissolves in austenitic manganese steel, which can inhibit the growth of grain structure, improve its hardenability, and austenitic manganese steel can obtain higher hardness and improved wear resistance.

[0015] Furthermore, after heat treatment, molybdenum infiltration and vapor deposition are carried out in sequence to form a molybdenum layer;

[0016] The process conditions for molybdenum infiltration are: the electrode spacing is 18 mm, the source voltage is 650 V, the source current is 1.4 - 1.6 V, the cathode voltage is 400 V, the cathode current is 3.8 - 4.0 A, the temperature is 940 - 960 °C, the atmosphere is argon, the working pressure is 35 Pa, the source is pure molybdenum, after sputtering for 1 - 3 h; passive electrode sputtering is carried out under the mask for 30 - 90 min;

[0017] The process conditions for vapor deposition are: using molybdenum hexafluoride and hydrogen as raw materials, the deposition temperature is 1000 - 1100 °C, the pressure is 2.0 - 2.7 kPa, and the duration is 90 - 120 min.

[0018] Furthermore, after vapor deposition, alloy powder is used to perform laser cladding on austenitic manganese steel to form a cladding layer;

[0019] The process conditions for laser cladding are: the laser power is 1150 - 1250 W, the scanning speed is 3.5 - 4.5 mm / s, and the powder feeding speed is 7.0 - 8.0 g / min; the laser spot diameter is 1.5 mm, the overlapping rate is 60%, the defocus amount is 15 mm, and both the powder feeding gas and the shielding gas are argon.

[0020] Furthermore, the thickness of the cladding layer is 1.5 - 2.0 mm.

[0021] Furthermore, the alloy powder is Ni60 alloy powder and aluminum nitride composite powder with a size of 45 - 106 μm, and the volume ratio is (5 - 7)∶(3 - 5);

[0022] Before use, it is dried at 150 °C for 60 min to remove moisture.

[0023] Further, the Ni60 alloy powder comprises the following mass components: 0.6-1.0% of carbon, 3.0-4.5% of silicon, 14-17% of chromium, 2.5-4.5% of boron, <15% of iron, 0.04-0.07% of lanthanum, and the balance being nickel.

[0024] Further, before laser cladding, the austenitic manganese steel is preheated at 150 °C for 60 min.

[0025] In the above technical solution, through the laser cladding technology, the alloy powder is melted in the flight space to form a micro-melting pool on the surface of the austenitic manganese steel. The alloy liquid forms a metallurgical bond with the manganese steel and forms a cladding layer. The overall dendritic structure is fine, the compositional difference between grain boundaries is small, the grain distribution is uniform, and there are hard borides and carbides in the structure. The addition of rare earth lanthanum makes the compounds finer and more dispersed, which can inhibit the segregation of harmful impurities at the grain boundaries, reduce the brittleness of the structure, alleviate the performance gradient difference between the cladding layer and the manganese steel matrix, effectively improve the surface hardness of the matrix, and has good wear resistance, corrosion resistance and high-temperature oxidation resistance. The surface roughness of the nickel-based cladding layer is low, and the machining amount of the parts after cladding is reduced; the thermal conductivity of metallic nickel is better. When it is set as the cladding layer on the surface of manganese steel, it can flatten the surface and remove the oxide layer; and it can reduce heat accumulation, optimize heat distribution, promote the rapid conduction and uniform distribution of temperature, and alleviate local overheating, thereby effectively improving the overall thermal conductivity of manganese steel.

[0026] By using aluminum nitride composite powder as the raw material, the cladding layer contains aluminum nitride. Aluminum nitride has extremely high thermal conductivity and hardness, which can further enhance the hardness and thermal conductivity of the cladding layer, and strongly promote the wear resistance and thermal conductivity of the overall manganese steel.

[0027] Preheating the workpiece to be treated (austenitic manganese steel) can slow down the temperature gradient, alleviate stress concentration, and reduce the cracking tendency of the cladding layer. Relatively high scanning speed and powder feeding rate can reduce the maximum temperature in the laser cladding process, which is helpful to obtain better performance of the cladding layer.

[0028] In the above technical solution, molybdenum is infiltrated on the surface of manganese steel by plasma metal infiltration technology to form an alloy layer rich in molybdenum metal on its surface, which can effectively improve the hardness and wear resistance of manganese steel and help improve its corrosion resistance. Then, passive electrode sputtering is carried out to pattern the surface of the alloy layer to form grooves. Then, using molybdenum hexafluoride as the molybdenum source, under the reduction action of hydrogen, chemical vapor deposition is carried out. Molybdenum metal is generated and deposited under high temperature and high pressure, and molybdenum elements migrate and grow from the alloy layer into the grooves, thus forming a molybdenum layer with interface voids that can promote the disappearance of dislocations and stress release. In laser cladding, molybdenum is solid-solved in nickel, further improving the corrosion resistance and high-temperature resistance of the cladding layer; at the same time, the interface voids can partially migrate into the cladding layer to form relatively dispersed nano-pores, which helps to relieve stress concentration, inhibit the initiation of cracks, promote the interaction between the surface and dislocations, improve its strength and plasticity, and can retain the thermal conductivity of the manganese steel matrix and its surface.

[0029] Further, the aluminum nitride composite powder is prepared by the following process:

[0030] Mix aluminum nitride, titanium powder and copper powder, and perform vacuum ball milling at 200 - 250 r / min for 10 - 12 h, then carry out spark plasma sintering. The sintering temperature is 950 - 970 °C, the heating rate is 100 °C / min, the loading pressure is 50 MPa, and the sintering duration is 10 - 12 min.

[0031] Further, the volume ratio of aluminum nitride, titanium powder and copper powder is 100∶(4.5 - 8.0)∶(90 - 110);

[0032] The particle sizes of aluminum nitride, titanium powder and copper powder are 2 - 30 μm.

[0033] In the above technical solution, active titanium elements and copper can generate TiN and CuTi phases on the surface of aluminum nitride to form an interface layer, realizing the interface bonding between aluminum nitride and copper, which helps the composite of aluminum nitride and copper. The deformation difficulty of the composite material increases, the anti-fatigue ability at the interface of the prepared cladding layer and its interface with the manganese steel matrix is improved, the sensitivity to temperature is reduced, and the strength and hardness are increased; moreover, both copper and titanium have high thermal conductivity, which helps to comprehensively improve the wear resistance and thermal conductivity of the manganese steel surface. Specific Embodiments

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Pig iron includes: by mass, carbon: 3.0%, manganese: 0.27%, silicon: 0.01%, phosphorus 0.035%, sulfur 0.03%, the balance being iron; pure iron: purity ≥ 99.9%; ferrochrome: chromium: 70%, carbon: 0.25%, silicon: 2.0%, the balance being iron; ferromanganese: manganese: 80%, carbon: 1.5%, silicon: 1.5%, the balance being iron; ferromolybdenum: molybdenum: 60%, carbon: 0.1%, silicon: 1.0%, the balance being iron; ferrotitanium: titanium: 70%, aluminum: 0.5%, silicon: 0.3%, the balance being iron; ferroniobium: niobium: 70%, carbon: 0.03%, silicon: 0.15%, the balance being iron; nitrided chromium: purity ≥ 99.6%, silicon: 1.0%, iron balance ≤ 0.35%;

[0036] The steel liquid components include the following components: by mass, carbon: 1.35%, manganese: 7.54%, molybdenum: 1.35%, chromium: 3.70%, silicon: 0.98%, nitrogen: 0.18%, titanium: 0.08%, niobium: 0.06%, phosphorus 0.045%, sulfur 0.01%, the balance being iron;

[0037] The Ni60 alloy powder includes the following mass components: carbon 0.8%, silicon 4.0%, chromium 16.0%, boron 4.0%, iron 8.0%, lanthanum 0.06%, the balance being nickel; the particle size range is 45 - 105 μm, and the average particle size is 57 μm;

[0038] Aluminum nitride, titanium powder, copper powder: purity ≥ 99.9%, the particle sizes are 25 μm, 1 μm, 15 μm in sequence; source pure molybdenum: purity ≥ 99.99%.

[0039] Example 1: A preparation method of a molybdenum - containing heat - conductive austenite, including the following processes:

[0040] Step 1: Mix and melt pig iron and pure iron at a temperature of 1420 °C; add ferrochrome, ferromanganese, ferromolybdenum, ferrotitanium, ferroniobium and nitrided chromium, the addition temperature of nitrided chromium is 1550 °C, and then continue melting for 40 min to form steel liquid; tap the furnace, the tapping temperature is 1520 °C, and pour, the pouring temperature is 1370 °C to obtain a blank;

[0041] Heat treatment, the process conditions are: first heat up at a heating rate of 50 °C / h to 650 °C and hold for 1 h; then heat up at a heating rate of 100 °C / h to 1050 °C and hold for 90 min; then water - cool, the water temperature is 10 °C, and the water temperature after water - cooling is 40 °C to obtain austenitic manganese steel;

[0042] Step 2: Using pure molybdenum as the source electrode, perform molybdenum infiltration on austenitic manganese steel. The process conditions are as follows: the electrode spacing is 18 mm, the source electrode voltage is 650 V, the source electrode current is 1.4 V, the cathode voltage is 400 V, the cathode current is 3.8 A, the temperature is 940 °C, the atmosphere is argon, the working pressure is 35 Pa, and the source electrode is pure molybdenum. After sputtering for 1 h; perform non-source electrode sputtering under the mask for 30 min;

[0043] Then, using molybdenum hexafluoride and hydrogen as raw materials, perform chemical vapor deposition. The process conditions are as follows: the deposition temperature is 1000 °C, the pressure is 2.0 kPa, and the duration is 90 min;

[0044] Step 3: Mix aluminum nitride, titanium powder, and copper powder, and perform spark plasma sintering after vacuum ball milling at 200 r / min for 10 h. The sintering temperature is 950 °C, the heating rate is 100 °C / min, the applied pressure is 50 MPa, and the sintering duration is 10 min; the volume ratio of aluminum nitride, titanium powder, and copper powder is 100∶4.5∶110;

[0045] Take the alloy powder to perform laser cladding on austenitic manganese steel to form a cladding layer and obtain manganese steel material; the alloy powder is Ni60 alloy powder and aluminum nitride composite powder, and the volume ratio is 7∶3; before use, dry it at 150 °C for 60 min to remove moisture; before laser cladding, preheat austenitic manganese steel at 150 °C for 60 min;

[0046] The process conditions for laser cladding are as follows: the laser power is 1150 W, the scanning speed is 3.5 mm / s, and the powder feeding speed is 7.0 g / min; the laser spot diameter is 1.5 mm, the overlapping rate is 60%, the defocus amount is 15 mm, and the powder feeding gas and protective gas are both argon.

[0047] Example 2: A preparation method of a molybdenum-containing heat-conducting austenite, including the following processes:

[0048] Step 1: Mix pig iron and pure iron and melt them at 1450 °C; add ferrochrome, ferromanganese, ferromolybdenum, ferro titanium, ferroniobium, and chromium nitride. The addition temperature of chromium nitride is 1560 °C, and then continue melting for 50 min to form molten steel; pour out, the pouring-out temperature is 1540 °C, and cast, the casting temperature is 1400 °C, to obtain a blank; perform heat treatment. The process conditions are as follows: first, heat up at a heating rate of 75 °C / h to 680 °C and hold for 2 h; then heat up at a heating rate of 120 °C / h to 1080 °C and hold for 95 min; then cool with water, the water temperature is 15 °C, and the water temperature after water cooling is 40 °C, to obtain austenitic manganese steel;

[0049] Step 2: Using pure molybdenum as the source electrode, perform molybdenum infiltration on austenitic manganese steel. The process conditions are as follows: the electrode spacing is 18 mm, the source electrode voltage is 650 V, the source electrode current is 1.5 V, the cathode voltage is 400 V, the cathode current is 3.9 A, the temperature is 950 °C, the atmosphere is argon, the working pressure is 35 Pa, and the source electrode is pure molybdenum. After sputtering for 2 h; perform non-source electrode sputtering under the mask for 60 min;

[0050] Then, using molybdenum hexafluoride and hydrogen as raw materials, perform chemical vapor deposition. The process conditions are as follows: the deposition temperature is 1050 °C, the pressure is 2.4 kPa, and the duration is 100 min;

[0051] Step 3: Mix aluminum nitride, titanium powder, and copper powder, and perform spark plasma sintering after vacuum ball milling at 220 r / min for 11 h. The sintering temperature is 960 °C, the heating rate is 100 °C / min, the applied pressure is 50 MPa, and the sintering duration is 11 min; the volume ratio of aluminum nitride, titanium powder, and copper powder is 100∶6∶100;

[0052] Take the alloy powder to perform laser cladding on austenitic manganese steel to form a cladding layer and obtain manganese steel material; the alloy powder is Ni60 alloy powder and aluminum nitride composite powder, and the volume ratio is 6∶4; before use, dry at 150 °C for 60 min to remove moisture; before laser cladding, austenitic manganese steel is preheated at 150 °C for 60 min;

[0053] The process conditions for laser cladding are as follows: the laser power is 1200 W, the scanning speed is 4.0 mm / s, and the powder feeding speed is 7.5 g / min; the laser spot diameter is 1.5 mm, the overlapping rate is 60%, the defocus amount is 15 mm, and the powder feeding gas and shielding gas are both argon.

[0054] Example 3: A preparation method of a molybdenum-containing heat-conducting austenite, including the following processes:

[0055] Step 1: Mix pig iron and pure iron and melt them at 1480 °C; add ferrochrome, ferromanganese, ferromolybdenum, ferro-titanium, ferro-niobium, and chromium nitride. The addition temperature of chromium nitride is 1570 °C, and then continue melting for 60 min to form molten steel; pour out of the furnace, the tapping temperature is 1550 °C, and cast, the casting temperature is 1420 °C, to obtain a billet; perform heat treatment. The process conditions are as follows: first, heat up to 700 °C at a heating rate of 100 °C / h and hold for 3 h; then heat up to 1110 °C at a heating rate of 150 °C / h and hold for 100 min; then cool with water, the water temperature is 20 °C, and the water temperature after water cooling is 40 °C, to obtain austenitic manganese steel;

[0056] Step 2: Using pure molybdenum as the source electrode, molybdenum infiltration is carried out on austenitic manganese steel. The process conditions are as follows: the electrode spacing is 18 mm, the source electrode voltage is 650 V, the source electrode current is 1.6 V, the cathode voltage is 400 V, the cathode current is 4.0 A, the temperature is 960 °C, the atmosphere is argon, the working pressure is 35 Pa, the source electrode is pure molybdenum. After sputtering for 3 h; passive electrode sputtering is carried out under the mask for 90 min;

[0057] Then, using molybdenum hexafluoride and hydrogen as raw materials, chemical vapor deposition is carried out. The process conditions are as follows: the deposition temperature is 1100 °C, the pressure is 2.7 kPa, and the duration is 120 min;

[0058] Step 3: Mix aluminum nitride, titanium powder and copper powder, and carry out spark plasma sintering after vacuum ball milling at 250 r / min for 12 h. The sintering temperature is 970 °C, the heating rate is 100 °C / min, the loading pressure is 50 MPa, and the sintering duration is 12 min; the volume ratio of aluminum nitride, titanium powder and copper powder is 100∶8∶110;

[0059] Take the alloy powder to carry out laser cladding on austenitic manganese steel to form a cladding layer and obtain manganese steel material; the alloy powder is Ni60 alloy powder and aluminum nitride composite powder, and the volume ratio is 5∶5; before use, it is dried at 150 °C for 60 min to remove moisture; before laser cladding, austenitic manganese steel is preheated at 150 °C for 60 min;

[0060] The process conditions of laser cladding are as follows: the laser power is 1250 W, the scanning speed is 4.5 mm / s, and the powder feeding speed is 8.0 g / min; the laser spot diameter is 1.5 mm, the overlapping rate is 60%, the defocus amount is 15 mm, and the powder feeding gas and the shielding gas are both argon.

[0061] Comparative Example 1: A preparation method of a molybdenum-containing heat-conducting austenite, including the following process:

[0062] Step 2: Using pure molybdenum as the source electrode, molybdenum infiltration is carried out on austenitic manganese steel. The process conditions are as follows: the electrode spacing is 18 mm, the source electrode voltage is 650 V, the source electrode current is 1.4 V, the cathode voltage is 400 V, the cathode current is 3.8 A, the temperature is 940 °C, the atmosphere is argon, the working pressure is 35 Pa, the source electrode is pure molybdenum, and sputtering is carried out for 1 h;

[0063] Steps 1 and 3 are the same as those in Example 1 to obtain manganese steel material.

[0064] Comparative Example 2: A preparation method of a molybdenum-containing heat-conducting austenite, Steps 1 and 2 are the same as Steps 1 and 3 in Example 1 to obtain manganese steel material.

[0065] Comparative Example 3: A preparation method of a molybdenum-containing heat-conducting austenite, including the following process:

[0066] Step 2: Take Ni60 alloy powder to perform laser cladding on austenitic manganese steel to form a cladding layer and obtain manganese steel material; before laser cladding, the austenitic manganese steel is preheated at 150°C for 60 minutes;

[0067] The process conditions of laser cladding are as follows: laser power 1150W, scanning speed 3.5mm / s, powder feeding speed 7.0g / min; laser spot diameter 1.5mm, overlapping rate 60%, defocusing amount 15mm, and both the powder feeding gas and the shielding gas are argon;

[0068] Step 1 is the same as that in Example 1 to obtain manganese steel material.

[0069] Experiment: Take the manganese steel materials obtained in Examples 1-3, Comparative Examples 1-3 and the austenitic manganese steel in Example 1 to prepare specimens, and detect and record their performance respectively:

[0070] Hardness test: First cut the specimen by electrical discharge machining, and use a Vickers hardness tester to detect its surface hardness. The specimen size is 20mm×20mm×10mm;

[0071] Wear resistance test: Use a wear testing machine to detect the wear mass loss of the specimen, and the wear time is 3h;

[0072] Thermal oxidation performance test: Use the weight gain method to detect the oxidation resistance of the specimen at 550°C, and take the weight gain of the specimen after 20h as the experimental index;

[0073] Fatigue resistance test: Use the microscopic crack observation method to compare the thermal fatigue performance from 700 to 25°C, and take the number of surface cracks of the specimen after 20h as the experimental index;

[0074] Corrosion resistance test: Use an electrochemical test system, use three electrodes, with platinum as the auxiliary electrode, saturated calomel as the reference electrode, and 3.5wt% sodium chloride solution as the electrolyte to perform potentiodynamic polarization curve testing, with a scanning speed of 0.001V / s, a scanning voltage range of -0.5V to 0.5V, and a scanning frequency of 10 -2 ~10 5 Hz.

[0075]

[0076] According to the data in the above table, the following conclusions can be clearly obtained:

[0077] Compare the manganese steel materials obtained in Examples 1-3, the manganese steel materials obtained in Comparative Examples 1-3 and the austenitic manganese steel in Example 1. From the test results, it can be seen that

[0078] Compared with the austenitic manganese steel in the comparative example and Example 1, the manganese steel materials obtained in Examples 1-3 have higher hardness, and lower wear amount, fatigue crack, oxidation weight gain and self-corrosion current data, which fully demonstrates that the present invention has achieved the improvement of the hardness, wear resistance, resistance to thermal and cold fatigue, thermal oxidation and corrosion resistance of the manganese steel materials.

[0079] Compared with Example 1, the gas-phase deposition process was not set in Comparative Example 1; the molybdenum infiltration and gas-phase deposition processes were not set in Comparative Example 2; the molybdenum infiltration and gas-phase deposition processes were not set in Comparative Example 3, and aluminum nitride composite powder was not added in the laser cladding process. The hardness of the manganese steel materials obtained in Comparative Examples 1-3 decreased, and the wear amount, fatigue crack, oxidation weight gain and self-corrosion current data deteriorated. It can be seen that the setting of the process and the components used for the manganese steel materials in the present invention can promote the comprehensive improvement of their hardness, wear resistance, resistance to thermal and cold fatigue, thermal oxidation and corrosion resistance.

[0080] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for preparing thermally conductive austenitic manganese steel containing molybdenum, characterized in that: Including the following processes: Pig iron and pure iron are mixed and smelted; ferrochrome, ferromanganese, ferromolybdenum, ferrotitanium, ferroniobium and chromium nitride are added and smelted to form molten steel; the steel is taken out of the furnace and poured to obtain billets; Heat treatment to obtain austenitic manganese steel; The austenitic manganese steel comprises the following mass components: carbon: 1.2-1.5%, manganese: 6-9%, molybdenum: 1-2%, chromium: 2-4%, silicon: 0.8-1.0%, nitrogen: 0.1-0.5%, titanium: 0.06-0.10%, niobium: 0.05-0.07%, phosphorus ≤0.07%, sulfur ≤0.04%, and the balance is iron; The process conditions of the heat treatment are: heating to 650-700°C at a heating rate of 50-100°C / h, keeping the temperature for 1-3h; then heating to 1050-1110°C at a heating rate of 100-150°C / h, keeping the temperature for 90-100min; and then water cooling; After heat treatment, molybdenum infiltration and vapor deposition are performed in sequence to form a molybdenum layer; The process conditions of molybdenum diffusion are as follows: the source electrode is pure molybdenum, the inter-electrode spacing is 18mm, the source voltage is 650V, the source current is 1.4-1.6V, the cathode voltage is 400V, the cathode current is 3.8-4.0A, the temperature is 940-960℃, the atmosphere is argon, the working pressure is 35Pa, and after sputtering for 1-3h; the passive electrode sputtering is carried out under the mask for 30-90min; The process conditions of vapor deposition are: using molybdenum hexafluoride and hydrogen as raw materials, the deposition temperature is 1000-1100°C, the pressure is 2.0-2.7 kPa, and the duration is 90-120 min; After vapor deposition, the alloy powder is taken to perform laser cladding on austenitic manganese steel to form a cladding layer.

2. The method for preparing a thermally conductive austenitic manganese steel containing molybdenum according to claim 1, characterized in that: The furnace temperature is 1520~1550℃, and the pouring temperature is 1370~1420℃.

3. The method for preparing a thermally conductive austenitic manganese steel containing molybdenum according to claim 1, characterized in that: The process conditions of laser cladding are: laser power 1150~1250W, scanning speed 3.5~4.5mm / s, powder feeding speed 7.0~8.0g / min; laser spot diameter 1.5mm, overlap rate 60%, defocus amount 15mm, powder feeding gas and shielding gas are argon.

4. The method for preparing a thermally conductive austenitic manganese steel containing molybdenum according to claim 1, characterized in that: The alloy powder is Ni60 alloy powder and aluminum nitride composite powder, and the volume ratio is (5-7): (3-5); The Ni60 alloy powder comprises the following mass components: 0.6-1.0% carbon, 3.0-4.5% silicon, 14-17% chromium, 2.5-4.5% boron, <15% iron, 0.04-0.07% lanthanum, and the balance is nickel; The aluminum nitride composite powder is prepared by the following process: aluminum nitride, titanium powder and copper powder are mixed, vacuum ball milled at 200-250 r / min for 10-12 hours, and then spark plasma sintered, the sintering temperature is 950-970°C, the heating rate is 100°C / min, the loading pressure is 50MPa, and the sintering time is 10-12 minutes.

5. A thermally conductive austenitic manganese steel containing molybdenum element obtained according to the preparation method according to any one of claims 1 to 4.

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