CN115074605A - Hot work die steel and preparation method thereof - Google Patents
Hot work die steel and preparation method thereof Download PDFInfo
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- CN115074605A CN115074605A CN202211002432.7A CN202211002432A CN115074605A CN 115074605 A CN115074605 A CN 115074605A CN 202211002432 A CN202211002432 A CN 202211002432A CN 115074605 A CN115074605 A CN 115074605A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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Abstract
The invention provides hot work die steel and a preparation method thereof. The hot work die steel is added with metal composite particles, the metal composite particles comprise a core layer and a shell layer, the core layer comprises titanium nitride, and the shell layer comprises titanium carbide. According to the invention, the effects of grain refinement and dislocation movement prevention are achieved by adding the metal composite particles, so that the prepared hot work die steel has excellent high-temperature strength and high-temperature fatigue performance.
Description
Technical Field
The invention relates to the technical field of die steel, in particular to hot work die steel and a preparation method thereof.
Background
The hot work die steel is an alloy tool steel suitable for producing a die for hot deforming a metal. Since the hot working mold works under high temperature and high pressure for a long time, the mold material is required to have high strength, hardness and thermal stability, and particularly, the hot working mold material should have high heat strength, thermal fatigue, toughness, wear resistance and the like. In order to meet the market demand for hot-work die steels having good properties, those skilled in the art have made many studies and improvements on hot-work die steels.
For example, chinese patent No. CN105950962B discloses a hot work die steel having both high temperature resistance and high toughness and a method for manufacturing the same, wherein the optimal mixture ratio is obtained by increasing the weight percentage of C to 0.50-0.65%, increasing the content of Mn to 0.6-1.0%, decreasing the content of Cr to 2.5-4.5%, increasing the weight percentage of Mo to 2.7-4.5%, and simultaneously adjusting the four chemical components, so that the manufactured die steel has excellent hardness, high temperature formation resistance, and high toughness.
For another example, chinese patent No. CN110863156B discloses a hot work die steel and its efficient preparation method, the hot work die steel has optimized alloy components, and uses the combined action of mechanical diffusion and thermal diffusion to homogenize the components of the hot work die steel, shorten the time required for homogenizing the alloy elements, improve the production efficiency, reduce the production cost, and the produced hot work die steel has a rockwell hardness of 55-57HRC, good isotropic properties, and good thermal stability.
According to the examples, the method for improving the performance of the hot-work die steel mostly adopts the adjustment of the alloy components of the hot-work die steel. However, in addition to the above-mentioned direction of improvement, it is also not negligible to change the properties of the die steel by adding other materials.
Specifically, the existing hot work die steel has more dislocations, and the dislocations are easy to move at high temperature, so that the performances of the hot work die steel such as high-temperature strength, high-temperature fatigue and the like are influenced.
Disclosure of Invention
The invention aims to provide hot-work die steel and a preparation method thereof, and provides hot-work die steel with excellent high-temperature strength and high-temperature fatigue performance. The scheme of the invention has important practical application value for replacing forging hot die steel by casting hot die steel and prolonging the service life of the hot die steel. In order to solve the above-mentioned technical problems, the present invention has been accomplished as described above.
The invention provides a preparation method of hot work die steel, which comprises the following steps: carbon, silicon, manganese, chromium, molybdenum, tungsten, vanadium, niobium, metal composite particles, phosphorus, sulfur and iron, wherein the mass part ratio of the metal composite particles to the carbon is 1: (3-5);
the preparation method comprises the following steps: preparing raw materials, and then sequentially carrying out converter smelting, LF refining, vacuum degassing, casting, homogenization treatment, fine grain treatment and modulation treatment to prepare hot work die steel; the modulation processing includes: performing high-temperature tempering treatment, performing at least two times of heating treatment, and then sequentially performing air cooling, water cooling, air cooling and oil cooling;
the metal composite particle comprises a core layer and a shell layer, wherein the core layer comprises titanium nitride, the shell layer comprises titanium carbide, and the metal composite particle is prepared by the following steps:
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid, stirring for 4-5 h, and drying at 60-80 ℃ for 10-12 h to prepare titanium-containing gel;
s920: coating titanium-containing gel on the outer side of titanium nitride particles with the particle size of 20-30 um to obtain a first intermediate;
s930: pre-sintering the first intermediate for at least two times to obtain a second intermediate;
s940: sintering the second intermediate at the high temperature of 1300-1500 ℃ to obtain metal composite particles;
wherein the mass ratio of polyacrylonitrile, tetrabutyl titanate and terephthalic acid is (1-5): (2-6): (0.5-1), the mass part ratio of the titanium-containing gel to the titanium nitride particles is (1-10): (1-6).
In the preparation steps, the metal composite particles are added into the hot-work die steel, so that dislocation motion in the hot-work die steel at high temperature can be prevented, and the high-temperature strength and the high-temperature fatigue performance of the hot-work die steel are improved. The utility model provides a hot work die steel is when preparing, add metal composite particle in the LF refining step, through vacuum degassing, casting, homogenization treatment, fine grain processing, the preparation obtains hot work die steel after steps such as modulation processing, it needs to explain, because add metal composite particle in the hot work die steel of this application, the alloy content of hot work die steel reduces, make hot work die steel can obtain through forged mode preparation, the current mode of forging hot work die steel has been replaced, hot work die steel's life has been prolonged. The structure of the metal composite particles is further improved, the titanium carbide layer is coated on the outer side of the titanium nitride, namely, the titanium nitride and titanium carbide composite particles are formed, the design is that in the practical application process, the pure titanium nitride particles are easy to break in the processes of molten steel, subsequent forging and the like, so that the effect of preventing dislocation movement of the pure titanium nitride particles is poor, and after the titanium nitride is coated on the outer side of the titanium nitride, the metal composite particles are not easy to break due to the fact that the hardness of the titanium carbide is higher than that of the titanium nitride, so that the high-temperature strength and the high-temperature fatigue performance of the hot work die steel are greatly improved. Because in this application be in the hot die steel of doing directly add metal composite particle, some metal composite particle can distribute on the surface of hot die steel, and the fragility on hot die steel surface increases, consequently, in the preparation method of this application, the surface to hot die steel has carried out quenching treatment, and quenching treatment includes the process of quenching twice at least for under the effect of water-cooling and oil-cooling double-deck quenching, the metal composite particle laminating of making hot die steel surface distribution is on the grain boundary, and hot die steel's hardness obtains promoting.
Further, the mass part ratio of the metal composite particles to the carbon is 1: (3.5-4.5).
The metal composite particles with the titanium carbide as the shell layer have the effects of refining crystal grains and inhibiting the growth of the crystal grains, and can improve the strength, the hardness and other properties of the hot-work die steel, so that the contents of alloy and carbon in the hot-work die steel can be correspondingly reduced, and the toughness and the shaping of the hot-work die steel can be improved under the condition that the strength and the hardness of the hot-work die steel are maintained at higher levels by the metal composite particles and the carbon in the proportion.
Further, the specific step of S920 includes: mixing the titanium-containing gel with titanium nitride particles with the particle size of 20-30 um, and stirring for 20-30 min to obtain a first intermediate.
Further, the specific step of S930 includes: primary presintering: heating the first intermediate to 200-300 ℃ at the speed of 4-6 ℃/min, and keeping the temperature for 2-3 h; secondary pre-sintering: and then heating to 550-650 ℃ at the speed of 2-3 ℃/min, and preserving the heat for 2-4 h to obtain a second intermediate.
Further, the specific step of S940 includes: and heating the second intermediate to 1300-1500 ℃ at the speed of 10-12 ℃/min, preserving the heat for 5-8 h, and grinding to obtain the metal composite particles.
Further, in 100 parts by mass of the hot work die steel, comprising: 0.25-0.40 mass part of carbon, 0.25-0.45 mass part of silicon, 0.52-0.56 mass part of manganese, 2.5-8.7 mass parts of chromium, 1.05-1.15 mass parts of molybdenum, 0.75-0.85 mass part of tungsten, 0.25-0.45 mass part of vanadium, 0.11-0.13 mass part of niobium, 0.08-0.09 mass part of metal composite particles, less than or equal to 0.015 mass part of phosphorus, less than or equal to 0.0008 mass part of sulfur and the balance of iron.
Further, the modulation processing specifically includes:
s71: heating the third module prepared after the fine grain treatment to 650-700 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module;
s72: heating the high-temperature tempering third module to 600-650 ℃, preserving heat for 1-2 h, heating to 800-850 ℃, preserving heat for 1-2 h, continuously heating to 1050-1100 ℃, preserving heat for 1-2 h, air cooling for 10-15 min, water cooling for 25-35 min, air cooling for 10-15 min again, and oil cooling for 200-300 min to obtain hot work die steel;
wherein the heating rate in S71 is 80 ℃/h-90 ℃/h; and/or
In S72, the heating rate is 105 ℃/h-115 ℃/h.
The preparation steps are that water cooling is carried out before oil cooling is carried out during quenching cooling, so that the crystal grains can be effectively prevented from growing rapidly, and the crystal grains in the hot die steel are kept in proper sizes, so that the hot die steel has good toughness and hardness.
Further, converter smelting specifically comprises:
s11: putting the raw materials into a converter for smelting and then tapping;
s12: after the aluminum blocks are added into the steel, a first mixture is obtained;
wherein the raw materials comprise molten iron, ferrochromium, ferromanganese and ferrosilicon.
Further, the LF refining specifically comprises:
s21: adding a desulfurizing agent and a deoxidizing agent into the first mixture;
s22: and performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture.
In the preparation steps, ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles are put in during LF refining, so that on one hand, the oxidation of the alloy can be prevented, and on the other hand, the metal composite particles can be uniformly mixed in the first mixture.
The invention also provides hot work die steel which is obtained by adopting the preparation method of any one of the technical schemes.
The hot-work die steel is obtained by the preparation method according to any one of the above technical schemes, so that the hot-work die steel has all the beneficial effects of the preparation method according to any one of the above technical schemes, and is not repeated herein.
Detailed Description
The following examples are illustrative only and are not to be construed as limiting the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a preparation method of hot-work die steel, which comprises the following steps of 100 parts by mass of the hot-work die steel: 0.25-0.40 mass part of carbon, 0.25-0.45 mass part of silicon, 0.52-0.56 mass part of manganese, 2.5-8.7 mass parts of chromium, 1.05-1.15 mass parts of molybdenum, 0.75-0.85 mass part of tungsten, 0.25-0.45 mass part of vanadium, 0.11-0.13 mass part of niobium, 0.08-0.09 mass part of metal composite particles, less than or equal to 0.015 mass part of phosphorus, less than or equal to 0.0008 mass part of sulfur and the balance of iron.
The main elements of the hot work die steel have the following functions:
carbon, an essential constituent element in steel, can determine the hardness of the steel and plays a fundamental role in other mechanical properties of the steel. The carbon element can form dispersed alloy carbide in the steel, so the carbon element has great influence on the strength, the plastic toughness and the like of the steel. After the content of the alloy elements is calculated, the content of the carbon elements is controlled to be 0.25-0.40%, and the generation of martensite can be guaranteed on the premise of dispersion strengthening.
Silicon is a strong ferrite strengthening element in steel, and in an oxidizing medium, silicon in the steel can form a silicon-rich surface layer on the surface, so that the oxidation resistance and corrosion resistance of the steel can be remarkably improved. Meanwhile, silicon is also an element for improving tempering resistance in steel, and can effectively reduce the diffusion speed of carbon in ferrite, so that carbides precipitated during tempering cannot be aggregated, and the tempering stability is further improved. In the die steel, as the silicon content increases, the brittleness of the die steel is significantly increased, and thus. The silicon content in the die steel is 0.25-0.45%.
Manganese, which is a solid solution strengthening element in steel, can refine grains and improve the mechanical property and hardenability of the steel. Manganese in the die steel can change the property and shape of oxides during solidification and improve the hot workability of the die steel, so that the content of manganese in the die steel is 0.52-0.56%.
Chromium is a solid-solution strengthening element in steel, and can improve the properties of the steel, such as strength, hardenability, oxidation resistance, and the like. In the die steel of the present invention, chromium is present in carbides to play a role in corrosion resistance. During tempering, chromium precipitates from the matrix to form an alloy compound, which can improve the temper softening resistance of the die steel. The chromium content in the die steel of the invention is 2.5-8.7%.
Molybdenum is a strengthening element of a precipitation hardening phase in steel, and can refine grains and improve the hardenability and the heat strength of the steel. In the die steel of the present invention, molybdenum and carbon form carbides, which can significantly improve the hardness of the die steel, and thus the content of molybdenum in the die steel of the present application is 1.05% to 1.15%.
Tungsten, which is a solid-solution strengthening element in steel, can improve the hardenability of materials, and can form carbides with a high melting point in die steel, and inhibit aggregation and growth of the carbides, thereby improving the high-temperature strength of the die steel, and therefore, the content of tungsten in the die steel of the present application is 0.75% to 0.85%.
Vanadium, which can refine grains and improve the hardness of the steel. In the die steel, vanadium can be precipitated in the form of carbide, the hardness and the strength of the steel are improved, and the content of vanadium in the die steel is 0.25-0.45%.
Niobium can refine grains and improve the hardness of the steel. In the die steel, niobium can be precipitated in the form of carbide, so that the toughness and the fatigue resistance of the steel are improved, and the content of niobium in the die steel is 0.11-0.13%.
The metal composite particles can play a role in preventing dislocation motion and improving the high-temperature strength and the high-temperature fatigue performance of the steel. The core layer of the metal composite particles is titanium nitride, the shell layer of the metal composite particles is titanium carbide, the particle size of the metal composite particles is 35-60 um, the hardness of the metal composite particles is very high, the metal composite particles have excellent high temperature resistance, and the metal composite particles in the hot-working die steel cannot change in a high-temperature environment, so that the metal composite particles have excellent capability of preventing dislocation movement. In the die steel of the present application, the content of the metal composite particles is 0.08% to 0.09%.
In the hot-work die steel, the properties of hardness, strength, toughness, fatigue resistance and the like of the hot-work die steel are improved by adding manganese, chromium, molybdenum, vanadium, niobium and tungsten. The metal composite particles can greatly improve the high-temperature strength and the high-temperature fatigue performance of the hot-work die steel.
As the structure of the metal composite particle is improved, there is also provided a method for preparing the above metal composite particle:
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid, stirring for 4-5 h, and drying at 60-80 ℃ for 10-12 h to prepare titanium-containing gel;
s920: mixing titanium-containing gel and titanium nitride particles with the particle size of 20-30 um, and stirring for 20-30 min to obtain a first intermediate;
s930: heating the first intermediate to 200-300 ℃ at the speed of 4-6 ℃/min, preserving heat for 2-3 h, heating to 550-650 ℃ at the speed of 2-3 ℃/min, and preserving heat for 2-4 h to obtain a second intermediate;
s940: and heating the second intermediate to 1300-1500 ℃ at the speed of 10-12 ℃/min, preserving the heat for 5-8 h, and grinding to obtain the metal composite particles.
Wherein the mass ratio of the polyacrylonitrile to the tetrabutyl titanate to the terephthalic acid is (1-5): (2-6): (0.5-1), the mass part ratio of the titanium-containing gel to the titanium nitride particles is (1-10): (1-6). Step S930 is to perform a preheating process on the first intermediate, convert polyacrylonitrile in the gel into a carbon material at a high temperature, and remove moisture in the gel at a high temperature to obtain titanium dioxide. In step S940, the carbon material is reacted with titanium dioxide at a higher temperature to finally prepare a titanium carbide shell.
In the raw material proportion of the hot work die steel, the mass part ratio of the metal composite particles to the carbon is 1: (3-5). The metal composite particles are added into the hot-work die steel, so that the using amount of carbon elements in the hot-work die steel can be reduced, and the toughness and the shaping of the hot-work die steel are improved. Specifically, the metal composite particles can also play roles in refining crystal grains and inhibiting the growth of the crystal grains, so that the amount of alloy elements for partially refining the crystal grains can be reduced, the amount of carbon elements is reduced, free carbon elements in steel are correspondingly reduced, and the toughness and the shaping of hot-work die steel can be improved on the premise of ensuring the strength, the hardness and other properties of the hot-work die steel. Preferably, the mass part ratio of the metal composite particles to the carbon is 1: (3.5-4.5).
As the metal composite particles are of a double-layer structure, the situation that titanium carbide of a shell layer falls off is found in the actual production process, crystal grains easily grow on the fallen titanium carbide, and the strength of the hot-working die steel is further influenced. Therefore, before titanium-containing gel coating is carried out on the titanium nitride particles, the titanium nitride particles can be subjected to surface treatment to strengthen the connection between the titanium nitride particles and the titanium carbide shell layer, and the specific steps of the surface treatment of the titanium nitride particles are as follows:
s951: preparing hydrofluoric acid with the concentration of 5% -15%, and introducing nitrogen into the hydrofluoric acid for stirring;
s952: adding titanium nitride particles into hydrofluoric acid, and introducing nitrogen into the titanium nitride particles for stirring for 20-30 min to obtain a first mixture;
s953: heating the first mixture to 110-120 ℃, introducing water vapor into the first mixture, and stirring the mixture for 20-30 min to obtain a second mixture;
s954: and filtering, cleaning and drying the second mixture to obtain titanium nitride particles with rough surfaces.
The application also provides a preparation method for directly preparing the titanium nitride particles with rough surfaces, the titanium nitride particles prepared by the method have excellent connection effect with the titanium carbide shell, the unshelling rate of the titanium nitride particles and the titanium carbide shell is less than 0.001%, and the preparation method comprises the following specific steps:
s961: mixing the components in parts by mass as follows: (0.1-0.3): (0.01-0.03): (10-15) mixing tetrabutyl titanate, cobalt nitrate, nitric acid and ethanol, and stirring at 60 ℃ for 20-24 hours to obtain cobalt-titanium gel;
s962: heating the cobalt-titanium gel to 800-950 ℃ at the speed of 7-9 ℃/min under the argon environment, and preserving the heat for 3-5 h to obtain a cobalt/titanium dioxide material;
s963: grinding a cobalt/titanium dioxide material, adding the ground cobalt/titanium dioxide material into a nitric acid solution with the mass fraction of 10% -15%, stirring for 5-8 h at the temperature of 60-80 ℃, and cleaning and drying to obtain loose titanium dioxide particles;
s964: and (3) putting the loose titanium dioxide particles into a reaction kettle, introducing nitrogen, heating to 1000-1300 ℃ at the speed of 10-12 ℃/min, and preserving heat for 8-12 h to obtain the titanium nitride particles with rough surfaces.
The titanium nitride particles with rough surfaces prepared by the method have the rough pore diameter of 30nm-50nm and excellent roughness.
Although the titanium carbide-coated metal composite particles have the effects of preventing dislocation movement and refining grains, it has also been found during production that some of the metal composite particles tend to form larger grains, which affect the hardness and toughness of the hot-work die steel. In order to inhibit the growth of the grains, the application also provides a method for solving the problem, in particular to a method for coating a carbon layer on the surface of a titanium carbide shell layer so that the titanium carbide shell layer can adsorb some alloy elements to inhibit the grain growth on the surface of the titanium carbide, and the carbon layer is coated on the surface of part of the titanium carbide shell layer.
The application provides a preparation method of the carbon-coated metal composite particles, which comprises the following specific steps:
s971: placing the metal composite particles in a fluidized bed at the temperature of 800-900 ℃ for fluidization, wherein the particle size of the particles is 50 um;
s972: and then heating the fluidized bed to 1300-1400 ℃, controlling the argon flow to be 8L/min and the ethylene flow to be 6L/min, and reacting for 3-5 min to obtain the carbon-coated metal composite particles.
In S972, ethylene is attached to the metal composite particle and carbonized at a high temperature, thereby achieving carbon coating of the metal composite particle.
The embodiment of the invention also provides a preparation method of the hot work die steel, which comprises the following specific steps:
s10: preparing raw materials, and smelting in a converter to obtain a first mixture;
s20: performing LF refining on the first mixture, and adding metal composite particles to obtain a second mixture;
s30: carrying out vacuum degassing on the second mixture to obtain a third mixture;
s40: casting the third mixture to obtain a first module;
s50: homogenizing the first module to obtain a second module;
s60: performing fine grain treatment on the second module to obtain a third module;
s70: and modulating the third module to obtain the hot work die steel.
The preparation method can improve the hardness, strength, toughness and high-temperature fatigue performance of the hot-work die steel through fine grain treatment and modulation treatment.
In S10, the embodiment of the invention firstly carries out converter smelting for steelmaking, and S10 comprises the following specific steps:
s11: preparing raw materials, putting the raw materials into a converter for smelting, and then tapping;
s12: after the aluminum blocks are added into the steel, a first mixture is obtained;
wherein the raw materials comprise molten iron, ferrochromium, ferromanganese and ferrosilicon.
In S11, molten iron, ferrochrome, ferromanganese and ferrosilicon are firstly put into the molten steel for smelting, so that the LF refining time can be shortened, the temperature reduction caused by adding a large amount of additives in the LF refining process is avoided, and the adsorption of oxygen and nitrogen in air caused by heating the molten steel is avoided. In S12, the addition of the aluminum nuggets after tapping can effectively perform deoxidation.
In S20, the first mixture is subjected to LF refining, which can adjust elements in molten steel and mix the components more uniformly, and S20 specifically comprises the following steps:
s21: adding a desulfurizing agent and a deoxidizing agent into the first mixture;
s22: and performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture.
Wherein the desulfurizer is aluminum powder and the deoxidizer is calcium oxide.
In step S30, the second mixture is subjected to vacuum degassing, and the vacuum degassing process can reduce hydrogen, nitrogen, oxygen, and the like in the molten steel, thereby improving the performance of the steel product. And in the vacuum degassing treatment, VD is adopted for vacuum degassing, the vacuum degree is controlled to be 60Pa-70Pa, the degassing time is controlled to be 20min-30min, and the hydrogen content in the discharged molten steel is less than 2 ppm.
In S40, in the embodiment of the present invention, the third mixture is cast, and the size of the first module obtained by casting is as follows: an equilateral wedge with a base 60mm x a base 80mm x a height 150 mm.
The invention carries out surface treatment on hot die steel after homogenization treatment, and comprises the following specific steps:
s81: heating the second module to 60-80 ℃, and keeping the temperature for 20-30 min;
s82: heating and mixing polyethylene wax and carbon powder in a mass ratio of 3:7, coating the mixture on the surface of the second module, performing carbon diffusion treatment by using laser irradiation, heating to 950-1000 ℃ at a speed of 12-15 ℃/min, keeping the temperature for 2-5 h, and cooling to room temperature.
Through the carbon diffusion treatment, the carbon source can be combined with the carbonized nitrogen of the shell layer of the metal composite particles, and further the effect of inhibiting the growth of crystal grains is achieved. Further, if the carbon diffusion treatment is performed on the hot work die steel, the carbon coating treatment of the metal composite material is not required because the metal composite material in which crystal grains are liable to grow is mainly distributed in the surface region of the hot work die steel. In the step S81, the preheating treatment can increase the adhesion of the mixture of polyethylene wax and carbon powder on the steel surface.
In S60, the second module is subjected to grain refining, which can improve strength, hardness, plasticity, and toughness of the die steel, and the finer the grains, the larger the grain boundary area, and the more unfavorable for crack propagation, the specific steps of S60 are as follows:
s61: heating the second module to 950-1100 ℃ at the speed of 120-140 ℃/h, and preserving heat for 60-90 min;
s62: cooling to 420-450 ℃ at the speed of 6-8 ℃/s, then air cooling to 270-300 ℃, and preserving heat for 8-9 h;
s63: then continuously heating to 670-680 ℃ at the speed of 100-120 ℃/h, preserving the heat for 6-9 h, and then cooling to room temperature at the speed of 7-9 ℃/s.
In S70, the embodiment of the present invention performs modulation processing on the third module, and the specific steps of S70 are as follows:
s71: heating the third module to 650-700 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module;
s72: and heating the high-temperature tempering third module to 600-650 ℃, preserving heat for 1-2 h, heating to 800-850 ℃, preserving heat for 1-2 h, continuously heating to 1050-1100 ℃, preserving heat for 1-2 h, air cooling for 10-15 min, water cooling for 25-35 min, air cooling for 10-15 min again, and oil cooling for 200-300 min.
In the above steps, high temperature tempering is performed in S71, and quenching is performed in S72. The cooling step of quenching comprises water cooling, air cooling and oil cooling, and the effects of inhibiting the growth of crystal grains and refining the crystal grains can be further achieved through the cooling steps of various types and the design of various alloys in the application.
Further, the heating rate in S71 is 80 ℃/h-90 ℃/h, and each heating rate in S72 is 105 ℃/h-115 ℃/h. The rapid growth of the crystal grains can be prevented at the above heating rate.
The following will describe in detail the method of manufacturing a hot-work die steel according to the present invention by using specific examples, in which the metal composite particles added in example 1 were not added, the metal composite particles added in example 2 were prepared in example 7, the metal composite particles added in example 3 were prepared in example 8, the metal composite particles added in example 4 were prepared in example 9, the carbon-coated metal composite particles added in example 5 were prepared in example 10, and the surface treatment step for the hot-work die steel was added in example 6. Examples 7-10 are the preparation of different types of metal composite particles.
Example 1
The hot-work die steel consists of the following components in percentage by weight:
0.35 percent of carbon, 0.28 percent of silicon, 0.54 percent of manganese, 6.85 percent of chromium, 2.1 percent of molybdenum, 0.78 percent of tungsten, 0.42 percent of vanadium, 0.12 percent of niobium, less than or equal to 0.0008 percent of sulfur, less than or equal to 0.0015 percent of phosphorus, and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten and ferroniobium to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, controlling the vacuum degree to be 65Pa, degassing time to be 25min, and controlling the argon flow to be 14-16m 3 H, pressure 0.3-0.4MPa, so that at the exitThe hydrogen content in the molten steel is less than 2 ppm;
s40: casting under the protection of mold flux to obtain a first module, wherein the composition of the mold flux is as follows: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluorine ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s60: heating the second module to 1050-1080 ℃ at the speed of 130 ℃/h, and preserving the heat for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
Example 2
The hot work die steel consists of the following components in percentage by weight:
0.35% of carbon, 0.28% of silicon, 0.54% of manganese, 6.85% of chromium, 2.1% of molybdenum, 0.78% of tungsten, 0.42% of vanadium, 0.12% of niobium, 0.08% of metal composite particles, less than or equal to 0.0008% of sulfur, less than or equal to 0.0015% of phosphorus and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, wherein the vacuum degree is 65Pa, and the degassing time is 25min, and controlling argon flow to be 14-16m 3 H, the pressure is 0.3-0.4Mpa, so that the hydrogen content in the steel liquid discharged from the station is less than 2 ppm;
s40: casting under the protection of mold flux to obtain a first module, wherein the composition of the mold flux is as follows: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluorine ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s60: heating the second module to 1050-1080 ℃ at the speed of 130 ℃/h, and preserving the heat for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
The above metal composite particles were prepared by example 7.
Example 3
The hot-work die steel consists of the following components in percentage by weight:
0.35% of carbon, 0.28% of silicon, 0.54% of manganese, 6.85% of chromium, 2.1% of molybdenum, 0.78% of tungsten, 0.42% of vanadium, 0.12% of niobium, 0.08% of metal composite particles, less than or equal to 0.0008% of sulfur, less than or equal to 0.0015% of phosphorus and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, controlling the vacuum degree to be 65Pa, degassing time to be 25min, and controlling the argon flow to be 14-16m 3 H, the pressure is 0.3-0.4Mpa, so that the hydrogen content in the steel liquid discharged from the station is less than 2 ppm;
s40: casting under the protection of the mold flux to obtain a first module, wherein the mold flux comprises the following components: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluoride ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s60: heating the second module to 1050-1080 ℃ at the speed of 130 ℃/h, and preserving the heat for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
The above metal composite particles were prepared by example 8.
Example 4
The hot work die steel consists of the following components in percentage by weight:
0.35% of carbon, 0.28% of silicon, 0.54% of manganese, 6.85% of chromium, 2.1% of molybdenum, 0.78% of tungsten, 0.42% of vanadium, 0.12% of niobium, 0.08% of metal composite particles, less than or equal to 0.0008% of sulfur, less than or equal to 0.0015% of phosphorus and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, then tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, controlling the vacuum degree to be 65Pa, degassing time to be 25min, and controlling the argon flow to be 14-16m 3 H, the pressure is 0.3-0.4Mpa, so that the hydrogen content in the steel liquid discharged from the station is less than 2 ppm;
s40: casting under the protection of mold flux to obtain a first module, wherein the composition of the mold flux is as follows: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluorine ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s60: heating the second module to 1050-1080 ℃ at the speed of 130 ℃/h, and preserving the heat for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
The above metal composite particles were prepared by example 9.
Example 5
The hot-work die steel consists of the following components in percentage by weight:
0.35% of carbon, 0.28% of silicon, 0.54% of manganese, 6.85% of chromium, 2.1% of molybdenum, 0.78% of tungsten, 0.42% of vanadium, 0.12% of niobium, 0.08% of carbon-coated metal composite particles, less than or equal to 0.0008% of sulfur, less than or equal to 0.0015% of phosphorus and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and then adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and carbon-coated metal composite particles to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, controlling the vacuum degree to be 65Pa, degassing time to be 25min, and controlling the argon flow to be 14-16m 3 H, the pressure is 0.3-0.4Mpa, so that the hydrogen content in the steel liquid discharged from the station is less than 2 ppm;
s40: casting under the protection of mold flux to obtain a first module, wherein the composition of the mold flux is as follows: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluorine ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s60: heating the second module to 1050-1080 ℃ at the speed of 130 ℃/h, and preserving the heat for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
The above carbon-coated metal composite particles were prepared by example 10.
Example 6
The hot-work die steel consists of the following components in percentage by weight:
0.35% of carbon, 0.28% of silicon, 0.54% of manganese, 6.85% of chromium, 2.1% of molybdenum, 0.78% of tungsten, 0.42% of vanadium, 0.12% of niobium, 0.08% of metal composite particles, less than or equal to 0.0008% of sulfur, less than or equal to 0.0015% of phosphorus and the balance of iron.
The preparation steps of the hot work die steel are as follows:
s10: preparing raw materials, putting the raw materials into a converter for smelting, tapping, and adding aluminum blocks into the tapped steel to obtain a first mixture;
s20: the mass portion ratio is 4: 5, adding calcium oxide and aluminum into the first mixture, then performing LF refining, and adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and metal composite particles to obtain a second mixture;
s30: performing VD vacuum degassing on the second mixture to obtain a third mixture, controlling the vacuum degree to be 65Pa, degassing time to be 25min, and controlling the argon flow to be 14-16m 3 H, the pressure is 0.3-0.4Mpa, so that the hydrogen content in the steel liquid discharged from the station is less than 2 ppm;
s40: casting under the protection of mold flux to obtain a first module, wherein the composition of the mold flux is as follows: 35% of calcium oxide, 30% of silicon dioxide, 3% of aluminum oxide, 2% of manganese oxide, 10% of sodium oxide, 5% of lithium oxide and 15% of fluorine ions;
s50: heating the first module to 1100-1150 ℃ and preserving heat for 20-22 h, and carrying out homogenization treatment to obtain a second module;
s80: heating the second module to 70 ℃, and keeping the temperature for 25 min; heating and mixing polyethylene wax and carbon powder in a mass ratio of 3:7, coating the mixture on the surface of the cleaned second module, performing carbon diffusion treatment by using laser irradiation, preserving heat at 970-980 ℃ for 4 hours, and cooling to room temperature;
s60: then the second module is heated to 1050-1080 ℃ at the speed of 130 ℃/h, and the temperature is kept for 70-80 min; cooling to 430-440 ℃ at the speed of 7 ℃/s, then air-cooling to 280-290 ℃, and preserving heat for 9 h; continuously heating to 670-680 ℃ at the speed of 110 ℃/h, preserving the heat for 8h, and cooling to room temperature at the speed of 8 ℃/s to obtain a third module;
s70: heating the third module to 680-690 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module; and heating the high-temperature tempering third module to 630-640 ℃, preserving heat for 1-2 h, heating to 830-840 ℃, preserving heat for 1-2 h, continuously heating to 1080-1100 ℃, preserving heat for 1-2 h, air-cooling for 12min, water-cooling for 33min, air-cooling again for 12min, and oil-cooling for 280min to obtain the hot work die steel.
The above metal composite particles were prepared by example 7.
Example 7
This example prepares a metal composite particle:
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid in a mass ratio of 5:6:0.5, stirring for 5 hours, and drying at the temperature of 80 ℃ for 11 hours to prepare titanium-containing gel;
s920: mixing titanium-containing gel with the mass ratio of 8:5 and titanium nitride particles with the particle size of 20-30 um, and stirring for 20-30 min to obtain a first intermediate;
s930: heating the first intermediate to 280 ℃ at the speed of 5 ℃/min, preserving heat for 2h-3h, heating to 620 ℃ at the speed of 3 ℃/min, and preserving heat for 2h-3h to obtain a second intermediate;
s940: and (3) heating the second intermediate to 1450 ℃ at the speed of 11 ℃/min, preserving heat for 6-7 h, and grinding to obtain the metal composite particles.
Example 8
This example prepares a metal composite particle:
s951: preparing hydrofluoric acid with the concentration of 8%, and introducing nitrogen into the hydrofluoric acid for stirring;
s952: adding titanium nitride particles into hydrofluoric acid, and introducing nitrogen into the titanium nitride particles for stirring for 25min to obtain a first mixture;
s953: heating the first mixture to 115 ℃, introducing water vapor into the first mixture, and stirring for 30min to obtain a second mixture;
s954: filtering, cleaning and drying the second mixture to obtain titanium nitride particles with rough surfaces;
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid in a mass ratio of 5:6:0.5, stirring for 5 hours, and drying at the temperature of 80 ℃ for 11 hours to prepare titanium-containing gel;
s920: mixing titanium-containing gel with the mass ratio of 8:5 and titanium nitride particles with the grain diameter of 20-30 um and rough surfaces, and stirring for 20-30 min to obtain a first intermediate;
s930: heating the first intermediate to 280 ℃ at the speed of 5 ℃/min, preserving heat for 2h-3h, heating to 620 ℃ at the speed of 3 ℃/min, and preserving heat for 2h-3h to obtain a second intermediate;
s940: and (3) heating the second intermediate to 1450 ℃ at the speed of 11 ℃/min, preserving the heat for 6-7 h, and grinding to obtain the metal composite particles.
Example 9
This example prepares a metal composite particle:
s961: mixing the components in parts by mass as follows: 0.2: 0.02: 12, mixing tetrabutyl titanate, cobalt nitrate, nitric acid and ethanol, and stirring at the temperature of 60 ℃ for 20-24 hours to obtain cobalt-titanium gel;
s962: heating the cobalt-titanium gel to 920 ℃ at the speed of 8 ℃/min under the argon environment, and preserving the heat for 4 hours to obtain a cobalt/titanium dioxide material;
s963: grinding the cobalt/titanium dioxide material, adding the ground cobalt/titanium dioxide material into a nitric acid solution with the mass fraction of 10%, stirring for 7 hours at the temperature of 70 ℃, and cleaning and drying to obtain loose titanium dioxide particles;
s964: placing the loose titanium dioxide particles into a reaction kettle, introducing nitrogen, heating the reaction kettle to 1250 ℃ at the speed of 12 ℃/min, and preserving heat for 10 hours to obtain titanium nitride particles with rough surfaces;
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid in a mass ratio of 5:6:0.5, stirring for 5 hours, and drying at the temperature of 80 ℃ for 11 hours to prepare titanium-containing gel;
s920: mixing titanium-containing gel with the mass ratio of 8:5 and titanium nitride particles with the grain diameter of 20-30 um and rough surfaces, and stirring for 20-30 min to obtain a first intermediate;
s930: heating the first intermediate to 280 ℃ at the speed of 5 ℃/min, preserving heat for 2h-3h, heating to 620 ℃ at the speed of 3 ℃/min, and preserving heat for 2h-3h to obtain a second intermediate;
s940: and (3) heating the second intermediate to 1450 ℃ at the speed of 11 ℃/min, preserving the heat for 6-7 h, and grinding to obtain the metal composite particles.
Example 10
This example prepares a carbon-coated metal composite particle:
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid in a mass ratio of 5:6:0.5, stirring for 5 hours, and drying at the temperature of 80 ℃ for 11 hours to prepare titanium-containing gel;
s920: mixing titanium-containing gel with the mass ratio of 8:5 and titanium nitride particles with the particle size of 20-30 um, and stirring for 20-30 min to obtain a first intermediate;
s930: heating the first intermediate to 280 ℃ at the speed of 5 ℃/min, preserving heat for 2h-3h, heating to 620 ℃ at the speed of 3 ℃/min, preserving heat for 2h-3h, and obtaining a second intermediate;
s940: heating the second intermediate to 1450 ℃ at the speed of 11 ℃/min, preserving heat for 6-7 h, and grinding to obtain metal composite particles;
s971: placing the metal composite particles in a fluidized bed at the temperature of 850 ℃ for fluidization, wherein the particle size of the particles is 50 um;
s972: and then heating the fluidized bed to 1400 ℃, controlling the argon flow to be 8L/min and the ethylene flow to be 6L/min, and reacting for 200s to obtain the carbon-coated metal composite particles.
And (4) performance testing:
the hot work die steels of examples 1 to 6 were subjected to a high temperature strength test using GB/T4338-2006 "method for high temperature tensile test of metallic materials", and the test results are shown in Table 1.
TABLE 1
| Examples | R m （MPa） | R p0.2 （MPa） |
| Example 1 | 618 | 408 |
| Example 2 | 689 | 466 |
| Example 3 | 695 | 487 |
| Example 4 | 705 | 495 |
| Example 5 | 720 | 506 |
| Example 6 | 692 | 485 |
From the above test results, it can be seen that the hot-work die steel added with the metal composite particles has better high-temperature strength, wherein the high-temperature strength of the hot-work die steel added with the carbon-coated metal composite particles can be further improved, and the high-temperature strength of the hot-work die steel added with the metal composite particles subjected to the surface roughening treatment is also improved to a certain extent.
The hot work die steels of examples 1 to 6 were subjected to high temperature strain fatigue life tests by using GB/T15248-2002 "method for testing axial equal amplitude low cycle fatigue of metallic materials", and the test results are shown in Table 2.
TABLE 2
From the above test results, it can be seen that the hot work die steel added with the metal composite particles has better high temperature fatigue performance, wherein the high temperature fatigue performance of the hot work die steel added with the carbon-coated metal composite particles is further improved, and the high temperature fatigue performance of the hot work die steel added with the metal composite particles subjected to the surface roughening treatment is also improved to a certain extent.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A preparation method of hot work die steel is characterized in that,
the hot work die steel comprises: carbon, silicon, manganese, chromium, molybdenum, tungsten, vanadium, niobium, metal composite particles, phosphorus, sulfur and iron, wherein the mass part ratio of the metal composite particles to the carbon is 1: (3-5);
the preparation method comprises the following steps: preparing raw materials, and then sequentially carrying out converter smelting, LF refining, vacuum degassing, casting, homogenization treatment, fine grain treatment and modulation treatment to prepare the hot work die steel; the modulation process includes: performing high-temperature tempering treatment, performing at least two times of heating treatment, and then sequentially performing air cooling, water cooling, air cooling and oil cooling;
the metal composite particle comprises a core layer and a shell layer, wherein the core layer comprises titanium nitride, the shell layer comprises titanium carbide, and the metal composite particle is prepared by the following steps:
s910: mixing polyacrylonitrile, tetrabutyl titanate and terephthalic acid, stirring for 4-5 h, and drying at 60-80 ℃ for 10-12 h to prepare titanium-containing gel;
s920: coating the titanium-containing gel on the outer side of titanium nitride particles with the particle size of 20-30 um to obtain a first intermediate;
s930: pre-sintering the first intermediate for at least two times to obtain a second intermediate;
s940: sintering the second intermediate at a high temperature of 1300-1500 ℃ to obtain the metal composite particles;
wherein the mass part ratio of the polyacrylonitrile to the tetrabutyl titanate to the terephthalic acid is (1-5): (2-6): (0.5-1), wherein the mass part ratio of the titanium-containing gel to the titanium nitride particles is (1-10): (1-6).
2. The production method according to claim 1, wherein the ratio of the metal composite particles to the carbon in parts by mass is 1: (3.5-4.5).
3. The method according to claim 1, wherein the step S920 comprises:
and mixing the titanium-containing gel with the titanium nitride particles with the particle size of 20-30 um, and stirring for 20-30 min to obtain the first intermediate.
4. The method according to claim 1, wherein the step S930 comprises:
primary presintering: heating the first intermediate to 200-300 ℃ at the speed of 4-6 ℃/min, and keeping the temperature for 2-3 h;
secondary pre-sintering: and then heating to 550-650 ℃ at the speed of 2-3 ℃/min, and preserving the heat for 2-4 h to obtain the second intermediate.
5. The preparation method according to claim 1, wherein the specific step of S940 includes:
and heating the second intermediate to 1300-1500 ℃ at the speed of 10-12 ℃/min, preserving the heat for 5-8 h, and grinding to obtain the metal composite particles.
6. The production method according to any one of claims 1 to 5,
in the hot work die steel, 100 parts by mass, comprising: 0.25-0.40 mass part of carbon, 0.25-0.45 mass part of silicon, 0.52-0.56 mass part of manganese, 2.5-8.7 mass parts of chromium, 1.05-1.15 mass parts of molybdenum, 0.75-0.85 mass part of tungsten, 0.25-0.45 mass part of vanadium, 0.11-0.13 mass part of niobium, 0.08-0.09 mass part of metal composite particles, less than or equal to 0.015 mass part of phosphorus, less than or equal to 0.0008 mass part of sulfur and the balance of iron.
7. The preparation method according to claim 6, wherein the modulation process specifically includes:
s71: heating the third module prepared after the fine grain treatment to 650-700 ℃, preserving heat for 5-12 h, and air-cooling to room temperature to obtain a high-temperature tempering third module;
s72: heating the high-temperature tempering third module to 600-650 ℃, preserving heat for 1-2 h, heating to 800-850 ℃, preserving heat for 1-2 h, continuously heating to 1050-1100 ℃, preserving heat for 1-2 h, air cooling for 10-15 min, water cooling for 25-35 min, air cooling for 10-15 min again, and oil cooling for 200-300 min to obtain the hot work die steel;
wherein the heating rate in the S71 is 80 ℃/h-90 ℃/h; and/or
The heating rate of each time in the S72 is 105 ℃/h-115 ℃/h.
8. The preparation method according to claim 6, wherein the converter smelting specifically comprises:
s11: putting the raw materials into a converter for smelting, and then tapping;
s12: after the aluminum blocks are added into the steel, a first mixture is obtained;
wherein, the raw materials comprise molten iron, ferrochrome, ferromanganese and ferrosilicon.
9. The preparation method according to claim 8, wherein the LF refining specifically comprises:
s21: adding a desulfurizing agent and a deoxidizing agent to the first mixture;
s22: and refining, and then adding ferromolybdenum, ferrovanadium, ferrotungsten, ferroniobium and the metal composite particles to obtain a second mixture.
10. A hot-work die steel, characterized in that it is produced by the production method according to any one of claims 1 to 9.
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