A method and product for efficient solid solution treatment of coarse primary carbides in high-carbon alloy steel

Abstract

This invention relates to a method and product for efficiently solidifying coarse primary carbides in high-carbon alloy steel, belonging to the field of high-carbon alloy steel production. The method includes the following steps: determining the thermodynamic equilibrium temperature A3 corresponding to the nominal composition of the high-carbon alloy steel billet or ingot for complete austenite transformation; calculating the degree of segregation of solute elements and the corresponding solidus temperature T based on the steel composition of the high-carbon alloy steel billet or ingot and the cooling rate under actual solidification conditions. SS During the cooling and solidification process or the heating and solution treatment process of high-carbon alloy steel billets or ingots, A3~T SS Electrical pulse treatment is performed within a temperature range of -200℃, followed by a period of treatment and air cooling to room temperature. The resulting billet or ingot is then heated to 900–1150℃ and held for 1–3 hours, followed by hot deformation and air cooling to room temperature. This invention achieves efficient solution treatment (annealing time ≤3 hours) of primary carbides in high-carbon alloy steel at relatively low temperatures (≤1150℃) through electrical pulse treatment during the cooling process of hot billets / ingots or the solution treatment process of cold billets / ingots.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-carbon alloy steel production, and particularly relates to a method for efficiently solid-solubilizing coarse primary carbides in high-carbon alloy steel and a product. BACKGROUND

[0002] High-carbon alloy steel includes tool steel, die steel, high-carbon martensitic stainless steel, and other steel types with high carbon content and alloy content, to obtain high hardness, oxidation resistance, and corrosion resistance at high temperatures, and is widely used in tools, cutters, abrasives, medical devices, petrochemicals, aerospace, and other fields. However, the common production technical bottleneck in the industrial production of this type of steel is that due to the high carbon content and alloy element content, a large amount of coarse primary alloy carbides is formed during solidification due to segregation and eutectic reaction. Such carbides are harmful to hot workability and toughness, and also waste alloy elements added to the steel; and to eliminate these coarse primary carbides, the solidified ingot / blank needs to be heated to a high enough temperature for a long time, but due to the significant segregation of alloy elements and carbon during solidification, the solidus temperature of the segregation zone of this type of steel decreases significantly, and a high heating temperature will cause the appearance of liquid phase and cracking of the ingot. Therefore, the heating temperature of high-carbon alloy steel is lower than that of other steels, which further prolongs the heating and holding time, and the homogenization annealing time of existing commercial large-size GCr15 bearing steel is generally more than 5 hours; this leads to a significant reduction in production efficiency, severe oxidation, coarse grains, and other problems. Therefore, it is urgent to develop a technology for efficiently solid-solubilizing coarse primary carbides in high-carbon alloy steel at a lower temperature.

[0003] Electro-pulse treatment is a non-equilibrium process that inputs electrical energy, thermal energy and strain energy into materials to induce significant changes in microstructure and mechanical properties. Currently, electro-pulse treatment has been widely used to refine the as-cast structure of metal materials, repair cracks, remove internal stress and promote the solid solution of second phases. For example, previous studies have found that the non-thermal effect of pulsed current can effectively promote the dissolution of Laves phase in Nb-containing high-strength non-oriented silicon steel [X. Li, B. Hu, H. Luo, et al. Characterizing changes in microstructures, mechanical and magnetic properties of non-oriented silicon steel due to pulsed current, Materials Characterization, 2024, 211: 113904.]; the pulsed current loading treatment before or after the solid solution treatment of high-speed steel rollers can effectively refine the grains, promote the rapid and uniform precipitation of carbides, and thus shorten the heat treatment process [Li Gui-rong, Wang Hong-ming, Guo Ya, Fu De, Zhu Xiang, Electro-pulse treatment method for improving heat treatment efficiency and microstructure quality of high-speed steel rollers, Patent No. CN 103014299 B, Patent Announcement Date 2014.12.03; Zhang Jia-tao, A method for preparing high solid solubility ultrafine grain high-speed steel using electro-pulse, Patent No. CN 109825689 B, Patent Announcement Date 2020.06.02]; In addition, electro-pulse treatment technology has also been used to regulate the second phase in the welded joints of Q890 and 42CrMo steels, two different materials, to improve the welding strength [Jiang Yan-bin, Tan Jian, Li Zhou, Xu Guo-fu, Long Jia-hui, A welding and electro-pulse heat treatment process for dissimilar alloys, Patent No. CN 114406512 A, Patent Announcement Date 2022.04.29].

[0004] The dissolution of the second phase promoted by the pulsed current is attributed to both thermodynamics and kinetics. Thermodynamically, due to the difference in electrical conductivity between the second phase and the matrix structure, the pulsed current loading process contributes additional phase transition Gibbs free energy, thereby reducing the dissolution temperature of the second phase; kinetically, the non-thermal effect of the pulsed current can effectively reduce the bonding force between the atoms in the microstructure matrix, reduce the energy barrier for atomic diffusion, and accelerate atomic diffusion and second phase dissolution. SUMMARY

[0005] In order to overcome the problems existing in the prior art, the present application provides a method for efficiently dissolving coarse primary carbides in high-carbon alloy steel and a product for overcoming the existing defects.

[0006] A method for efficiently dissolving coarse primary carbides in high-carbon alloy steel, the method comprising the steps of:

[0007] S1. determining the thermodynamic equilibrium temperature A3 of complete phase transformation into austenite corresponding to the nominal composition of the high-carbon alloy steel casting blank or ingot;

[0008] S2. calculating the segregation degree of solute elements and the corresponding solidus temperature T SS according to the steel composition of the high-carbon alloy steel casting blank or ingot and the cooling speed under the actual solidification conditions;

[0009] S3. performing electric pulse treatment on the high-carbon alloy steel casting blank or ingot in the temperature range of A3~T SS -200℃ during the cooling solidification process or the heating solid solution process, treating for a period of time and air cooling to room temperature;

[0010] S4. heating the casting blank or ingot obtained in S3 to 900~1150℃ and holding for 1~3h, then hot deforming and air cooling to room temperature.

[0011] According to the above-mentioned aspect and any possible implementation manner, further provided is an implementation manner, wherein the cooling solidification process specifically comprises: applying electric pulse to the high-carbon alloy steel casting blank or ingot when the high-carbon alloy steel casting blank or ingot is cooled to the temperature range of A3~T SS -200℃ during the solidification process, and keeping the temperature of the high-carbon alloy steel casting blank or ingot in the above-mentioned temperature range; after the electric pulse treatment for 0.5~180min, the pulse current is removed, and then air cooling to room temperature is performed.

[0012] According to the above-mentioned aspect and any possible implementation manner, further provided is an implementation manner, wherein the heating solid solution process comprises: heating the cold high-carbon alloy steel blank by using electric pulse treatment or electric pulse coupled with heat treatment, and after the temperature is raised to the range of A3~T SS -200℃, holding for 0.5~180min, and then air cooling to room temperature.

[0013] According to the above-mentioned aspect and any possible implementation manner, further provided is an implementation manner, wherein the performance parameters of the electric pulse are as follows: pulse frequency 500~2000Hz, duty cycle 5~15% and current density 10~100A·mm -2 .

[0014] According to the above-mentioned aspect and any possible implementation manner, further provided is an implementation manner, wherein the pulse frequency is 1000Hz, the duty cycle is 10%, and the current density is 15A·mm -2 .

[0015] According to the above-mentioned aspect and any possible implementation manner, further provided is an implementation manner, wherein the pulse frequency is 1000Hz, the duty cycle is 8%, and the current density is 25A·mm -2 .

[0016] According to the aspect and any possible implementation manner as described above, further provided is an implementation manner, wherein the parameters of the electric pulse are: a pulse frequency of 0-2000 Hz, a duty cycle of 0-15%, and a current density of 0-200 A·mm -2 .

[0017] According to the aspect and any possible implementation manner as described above, further provided is an implementation manner, wherein the long axis size of the grain boundary carbide in the cast blank or cast ingot after the S1-S3 treatment is less than or equal to 10 μm or less than or equal to 1 / 5 of the maximum carbide size in the cast blank or cast ingot before the electric pulse treatment; or the long axis size of the grain boundary carbide after the S1-S4 treatment is less than or equal to 1 / 10 of the maximum carbide size in the cast blank or cast ingot.

[0018] The application further provides a high-carbon alloy steel prepared by the method, and the high-carbon alloy steel comprises the following components in percentage by mass: C: 0.6-1.7%, Cr: 0-18%, Mn: 0-30%, Al: 0-13%, Ni: 0-10%, Mo: 0-5%, W: 0-2%, Si: 0-3.0%, Ti: 0-1.0%, Nb: 0-1.0%, V: 0-1.0%, P≤0.01%, S≤0.01%, and the rest is Fe and inevitable impurities.

[0019] According to the aspect and any possible implementation manner as described above, further provided is an implementation manner, wherein the long axis size of the grain boundary carbide in the high-carbon alloy steel is less than or equal to 5 μm.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The method for removing coarse primary carbides in a high-carbon alloy steel provided by the application comprises the following steps: determining the thermodynamic equilibrium temperature A3 of complete phase transition into austenite corresponding to the nominal composition of the high-carbon alloy steel cast blank or cast ingot; calculating the segregation degree of solute elements and the corresponding solidus temperature T SS in the high-carbon alloy steel cast blank or cast ingot according to the composition of the high-carbon alloy steel cast blank or cast ingot and the cooling speed under the actual solidification conditions; and performing A3-T SS- the electric pulse treatment is performed in the temperature range of 200 ℃, the treatment is performed for a period of time and air cooling is performed to room temperature; the obtained cast billet or ingot is heated to 900-1150 ℃ and held for 1-3 h, and then hot deformation is performed and air cooling is performed to room temperature. The electric pulse treatment technology is applied to the solidification cooling process and high-temperature solid solution process of high-carbon alloy steel, and the maximum carbide size in the cast steel and forged steel is significantly refined. The electric pulse treatment is performed in the solidification process and solid solution treatment process of high-carbon alloy steel far below the solidus temperature range, which significantly promotes the solid solution of primary carbides and the diffusion of alloying elements, and finally shortens the homogenization time to within 3 h, and significantly improves the production efficiency. In addition, compared with the traditional solid solution treatment, the electric pulse treatment process significantly refines the primary carbide size in the high-carbon alloy steel cast billet / ingot, forged steel and rolled material. The length of the grain boundary carbide in the high-carbon alloy steel cast billet / ingot prepared by the electric pulse treatment is ≤10 μm or ≤ 1 / 5 of the maximum carbide size in the cast billet / ingot before the electric pulse treatment; after forging or rolling, the maximum carbide size is ≤5 μm or ≤ 1 / 10 of the maximum carbide size in the cast billet / ingot. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The method flowchart of the present application is shown in the figure;

[0023] Figure 2 The microstructure diagram of the GCr15 bearing steel in Example 1 of the present application after the electric pulse treatment and hot deformation is shown in the figure;

[0024] Figure 3 The microstructure diagram of the GCr15 bearing steel in Example 1 of the present application after the conventional solid solution treatment and hot deformation is shown in the figure;

[0025] Figure 4 The microstructure diagram of the high-carbon stainless steel in Example 2 of the present application after the electric pulse treatment and hot deformation is shown in the figure;

[0026] Figure 5 The microstructure diagram of the high-carbon stainless steel in Example 2 of the present application after the conventional solid solution treatment and hot deformation is shown in the figure. DETAILED DESCRIPTION

[0027] In order to better understand the technical solutions of the present application, the content of the present application includes but is not limited to the specific embodiments in the following, and similar technologies and methods should be regarded as within the scope of protection of the present application. In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0028] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0029] like Figure 1 As shown, the present invention provides a method for efficiently solid-solution treating coarse primary carbides in high-carbon alloy steel, the method comprising the following steps:

[0030] S1. Determine the thermodynamic equilibrium temperature A3 for the complete phase transformation to austenite corresponding to the nominal composition of the high-carbon alloy steel billet or ingot;

[0031] S2. Based on the composition of the high-carbon alloy steel billet or ingot and the cooling rate under actual solidification conditions, calculate the degree of segregation of solute elements and the corresponding solidus temperature T. SS ;

[0032] S3. A3~T during the cooling and solidification process or the heating and solution treatment process of high-carbon alloy steel billets or ingots. SS Perform electrical pulse treatment within a temperature range of -200℃, treat for a period of time, and then air cool to room temperature;

[0033] S4. Heat the billet or ingot obtained in S3 to 900-1150℃ and hold for 1-3 hours, then perform hot deformation and air cool to room temperature.

[0034] Specifically, the implementation process of this invention is as follows:

[0035] (1) Since the solid solubility of carbide-forming elements (including C, Cr, Mn, etc.) in face-centered cubic phases is much higher than that in body-centered cubic phases, carbide solution treatment is generally performed above the complete austenitizing temperature. Therefore, the design of the electro-pulse solution treatment process first requires calculating and determining the thermodynamic equilibrium temperature A3 at which ferrite is completely transformed into austenite when the temperature is increased at the nominal composition of the steel being treated.

[0036] (2) In order to prevent the temperature rise of the steel sample during the electrical pulse treatment process from exceeding the solidus temperature, it is also necessary to calculate the solidus temperature T corresponding to the non-equilibrium solidification process of the steel under actual solidification conditions. SS ;

[0037] (3) Based on the calculation results of (1) and (2), the temperature range for electrical pulse treatment is set to A3~T. SS At -200℃, electrical pulse processing can be performed in the following manner:

[0038] a. Cooling to A3~T during the solidification process of high-carbon alloy steel. SSAn electrical pulse is applied within a temperature range of -200℃, utilizing the Joule heating effect of the pulsed current to maintain the billet temperature within the target range for solid solution of carbides. After electrical pulse treatment for 0.5-180 minutes, the pulsed current is removed, and the billet or ingot is allowed to air cool to room temperature.

[0039] b. Heating cold high-carbon alloy steel billets to A3~T using a single electrical pulse treatment or a coupling method of electrical pulse + conventional heat treatment. SS A target temperature between -200℃ is maintained for 0.5 to 180 minutes, followed by air cooling to room temperature.

[0040] (4) The billet or ingot obtained in step (3) is heated to 900-1150℃ by conventional heating or electric pulse assisted heating and held for 1-3 hours. It is then rolled / forged at 800-1100℃ with a deformation amount of 10-95%, and then air-cooled to room temperature.

[0041] Preferably, before the steel billet is treated with pulsed current, impurities and contaminants on the surface of the billet are removed by grinding, allowing the billet to make full contact with the electrode. One end of the clamping device is connected to the pulse generator, and the other end, either a clamp or a contact, contacts the billet, connecting them so that the generated continuous electrical pulses act directly on the billet. A computer controls the output of the pulsed current and adjusts parameters such as the current magnitude and frequency, transmitting the commands to the pulsed current generator via a network cable. Ultimately, the Joule heating and electrical effects of the electrical pulses are used to control the carbides.

[0042] This invention optimizes the preparation process of high-carbon alloy steel by means of electrical pulse treatment. It proposes a method to dissolve primary carbides in high-carbon alloy steel by considering the current density, pulse frequency, duty cycle of the electrical pulse; solution temperature and time; and hot deformation temperature and reduction, so as to achieve the goal of simultaneously shortening the solution annealing time of high-carbon alloy steel and refining the primary carbides.

[0043] Preferably, in step (4), the heat distortion temperature range is 800–1100°C, and the deformation amount is 10–95%.

[0044] Preferably, the total processing time for steps (3) and (4) does not exceed 3 hours, and the maximum temperature of the processed sample does not exceed 1150°C.

[0045] The high-carbon alloy steel billet used in this invention can be a sample steel prepared in the laboratory or a large-scale commercial product prepared by a steel company.

[0046] After treatment in steps (1) to (3), the long axis dimension of the grain boundary carbides in the billet does not exceed 10 μm or is ≤ 1 / 5 of the maximum carbide size in the billet / ingot before the electric pulse treatment, or after treatment in steps (1) to (4), the long axis dimension of the grain boundary carbides in the forged steel does not exceed 5 μm or is ≤ 1 / 10 of the maximum carbide size in the billet / ingot.

[0047] The present invention also provides a high-carbon alloy steel, which is obtained by the electrical pulse treatment method described in the present invention.

[0048] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the composition of the high-carbon alloy steel comprises, by mass percentage: C: 0.6–1.7%, Cr: 0–18%, Mn: 0–30%, Al: 0–13%, Ni: 0–10%, Mo: 0–5%, W: 0–2%, Si: 0–3.0%, Ti: 0–1.0%, Nb: 0–1.0%, V: 0–1.0%, P ≤ 0.01%, S ≤ 0.01%, with the remainder being Fe and unavoidable impurities. Wherein, the long axis dimension of the grain boundary carbides in the high-carbon alloy steel is less than or equal to 5 μm.

[0049] The following specific examples will be used to demonstrate this:

[0050] In the following embodiments of the present invention, scanning electron microscopy and optical microscopy were used to observe the microstructure. The embodiments of the present invention followed standard metallographic preparation methods: the surface of the bearing steel perpendicular to the rolling direction was polished using 240-grit, 600-grit, 1000-grit, and 2000-grit sandpaper; and polished using water-soluble diamond polishing paste. When observing the microstructure of the electrically pulsed samples, a 4% (v / v) nitric acid-alcohol solution was used for etching at room temperature for 5-15 seconds.

[0051] Example 1: The electro-pulse treatment technology of the present invention was used to process a hot-state continuous casting billet of GCr15 bearing steel (Fe-0.98C-0.26Cr-0.024Ni-0.33Mn-0.01Cu-1.46Cr-0.01P (wt.%), with a cross-section of 160mm × 160mm and a flame-cut length of 11m. The process included the following steps:

[0052] (1) The thermodynamic equilibrium temperature at which all ferrite in the high carbon stainless steel studied is converted into austenite is 747℃, calculated using ThermalCalc software.

[0053] (2) The cooling rate of solidification during the continuous casting process of small billets is generally between 0.5 and 1℃ / s. The non-equilibrium solidification process of the steel under study was simulated and calculated using the "Schei1 solidification process simulation" module in ThermalCalc software. The average solidus temperature of the steel under study in the above cooling rate range was 1308±5℃.

[0054] (3) Based on the size and physical properties of the billet, design and install a pulse current loading device that can apply the electric pulse process parameters described in this invention to both sides of the billet.

[0055] (4) When the continuous casting billet is completely solidified and after being flame-cut, the corner temperature drops to about 800°C; at this time, the pulse current is applied to the two opposite sides of the billet.

[0056] The pulse frequency is 1000Hz, the duty cycle is 10%, and the current density is 15A·mm.

[0057] - 2 The billet temperature was maintained between 650 and 1000℃. After 10 minutes of electrical pulse treatment, the pulse current was removed, and the ingot was air-cooled to room temperature.

[0058] (5) Heat the continuous casting billet obtained in step (3) to 1100°C using conventional heating methods.

[0059] Hold at ℃ for 2 hours, then hot roll to a round billet with a diameter of 75mm.

[0060] Figure 2 The image shows the SEM image of the microstructure of GCr15 rolled steel prepared using the above method. It can be seen that the microstructure of the prepared steel consists of lamellar pearlite, and no significant network carbides were found at the grain boundaries. Figure 3 The microstructure of GCr15 bearing steel rolled product prepared by conventional heat treatment at the same solution temperature shows a large number of coarse network carbides at the grain boundaries, with short axis lengths of 0.5–1.5 μm and long axis lengths exceeding 50 μm. Comparative experiments demonstrate that the electro-pulse treatment technology of this invention can effectively dissolve and break down coarse network carbides in high-carbon chromium bearing steel.

[0061] Example 2: The electro-pulse treatment technology of the present invention was used to treat a cold-state square billet ingot of high-carbon stainless steel Fe-1.0C-14Cr-0.3Si-0.3Mn-1Mo-1W (wt.%) with a cross-section of 60mm×60mm and a length of 0.5m. The process included the following steps:

[0062] (1) The thermodynamic equilibrium temperature at which all ferrite in the high carbon stainless steel studied is converted into austenite is 815℃, calculated using ThermalCalc software.

[0063] (2) The cooling rate of solidification of the molded billet is generally around 1℃ / s. The non-equilibrium solidification process of the steel was simulated and calculated using the "Schei1 solidification process simulation" module in ThermalCalc software. The average solidus temperature of the steel in the above cooling rate range was 1229℃.

[0064] (3) Based on the size and physical properties of the ingot, design and install a process pulse current loading device that can apply the process pulse current loading device described in this invention to both ends of the ingot during the billet heating process.

[0065] (4) The obtained cold-state mold casting billet is heated using electric pulse-assisted heating, with a target temperature of 1000℃. Specifically, a large box furnace is used for heating, while pulsed current is applied to both ends of the ingot. The pulse frequency is 1000Hz, the duty cycle is 8%, and the current density is 25A·mm². -2 The temperature was raised to 1000℃ under the action of box furnace and pulsed current heating effect, held at 1000℃ for 1 hour, and then air-cooled to room temperature;

[0066] (5) The ingot after the electric pulse treatment obtained in step (3) is heated to 1150℃ and held for 2 hours by conventional heating method, rolled to 5mm between 800 and 1100℃, and then air-cooled to room temperature.

[0067] Figure 4 The image shows the microstructure of the high-carbon stainless steel rolled product prepared above. It can be seen that no large, interconnected carbides forming a network were found at the grain boundaries of the prepared steel, and the maximum long axis dimension of the carbides at the grain boundaries is less than 5 μm. This indicates that the pulsed current dissolved the carbides with a long axis dimension greater than 5 μm in the high-carbon alloy steel. Figure 5 The image shows the microstructure of rolled steel prepared using a traditional solution treatment and rolling process. It can be seen that a large number of coarse carbides exist at the grain boundaries, with the largest long axis reaching 50 μm. This indicates that the electro-pulse treatment technology in this invention can effectively dissolve the coarse primary carbides in high-carbon stainless steel.

[0068] Example 3: The electro-pulse treatment technology of the present invention was used to treat a cold-cast ingot of Cr12Mo1V1 mold steel Fe-1.57C-0.25Si-0.28Mn-11.35Cr-0.75Mo-1V (wt.%) prepared in the laboratory. The ingot had a cross-sectional dimension of 30mm × 60mm and a length of 200mm. The process included the following steps:

[0069] (1) The thermodynamic equilibrium temperature at which all ferrite in the high carbon stainless steel studied is converted into austenite is 813℃, calculated using ThermalCalc software.

[0070] (2) The cooling rate of the solidification of the ingot is generally between 1 and 3℃ / s. The non-equilibrium solidification process of the steel under study was simulated and calculated using the "Schei1 solidification process simulation" module in ThermalCalc software. The average solidus temperature of the steel under study in the above cooling rate range was 1253±8℃.

[0071] (3) Grind both sides of the ingot to remove the iron oxide scale, and apply a pulsed current to both sides of the ingot. At this time, the pulse frequency is 1000Hz, the duty cycle is 15%, and the current density is 10A·mm. -2 The billet temperature was maintained between 900 and 950°C. After 30 minutes of electrical pulse treatment, the pulse current was removed, and the ingot was air-cooled to room temperature.

[0072] (4) The ingot obtained in step (3) is heated to between 1000 and 1050°C using electric pulse-assisted heating and held at that temperature for 1 hour. At this time, the pulse frequency is 2000 Hz, the duty cycle is 8%, and the current density is 15 A·mm². -2 The ingots heated by the above electric pulse are hot rolled into 10mm thick sheets through 5 passes.

[0073] Metallographic methods were used to statistically analyze the size of coarse grain boundary carbides in the as-cast microstructure of Cr12Mo1V1 mold steel and in the microstructure of the thin plate treated with the method of this invention. It was found that the average long axis dimension of carbides in the ingot was 65±6 μm, while the average long axis dimension of carbides in the thin plate treated with the method of this invention was 6±4 μm, which is less than 1 / 10 of the long axis dimension of carbides before treatment.

[0074] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0075] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method of efficiently dissolving coarse primary carbides in a high carbon alloy steel, characterized by, The high-carbon alloy steel is GCr15 bearing steel, high-carbon stainless steel or Cr12Mo1V1 die steel, and the method comprises the steps of: S1. determining the thermodynamic equilibrium temperature A3 of complete phase transition to austenite corresponding to the nominal composition of the high-carbon alloy steel cast blank or ingot; S2. According to the high-carbon alloy steel composition and the actual cooling rate under the solidification condition, the degree of segregation of solute elements and the corresponding solidus temperature T are calculated SS ; S3. A3~T during the cooling and solidification process or the heating and solution treatment process of high-carbon alloy steel billets or ingots. SS Electrical pulse treatment is performed within a temperature range of -200℃, followed by a period of treatment and air cooling to room temperature. Specifically, during the heating and solution treatment process, the cold high-carbon alloy steel billet is heated to A3~T using electrical pulse treatment or a combination of electrical pulse and heat treatment. SS After reaching -200 ℃, hold at that temperature for 0.5 to 180 min, then air cool to room temperature; the cooling and solidification process specifically includes: applying an electric pulse when the high carbon alloy steel billet or ingot is cooled to the temperature range between A3 and Tss-200 ℃ during the solidification process, so that the temperature of the high carbon alloy steel billet or ingot is maintained within the above temperature range; after the electric pulse treatment for 0.5 to 180 min, remove the pulse current, and then air cool to room temperature; S4. heating the cast blank or ingot obtained in S3 to 900-1150 ℃ for 1-3 h, then hot deforming, the deformation amount being 10-95%, and air cooling to room temperature; The grain boundary carbide long axis size in the cast blank or ingot after S1-S3 treatment is less than or equal to 10 μm or less than or equal to 1 / 5 of the maximum carbide size in the cast blank or ingot before the electric pulse treatment; or the grain boundary carbide long axis size after S1-S4 treatment is less than or equal to 1 / 10 of the maximum carbide size in the cast blank or ingot.

2. The method of claim 1, wherein, The performance parameters of the electric pulse are: pulse frequency 500-2000 Hz, duty cycle 5-15%, and current density 10-100 A·mm -2 .

3. The method of claim 2, wherein, The pulse frequency is 1000 Hz, the duty cycle is 10%, and the current density is 15 A mm -2 .

4. The method of claim 2, wherein, The pulse frequency is 1000 Hz, the duty cycle is 8%, and the current density is 25 A mm -2 .

5. The method of claim 1, wherein, The parameters of the electric pulse are: pulse frequency 0-2000 Hz, duty cycle 0-15%, and current density 0-200 A·mm -2 .

6. A high carbon alloy steel characterized in that, The high-carbon alloy steel is prepared by the method in any one of claims 1-5, and the composition of the high-carbon alloy steel comprises, by mass percentage, C: 0.6-1.7%, Cr: 0-18%, Mn: 0-30%, Al: 0-13%, Ni: 0-10%, Mo: 0-5%, W: 0-2%, Si: 0-3.0%, Ti: 0-1.0%, Nb: 0-1.0%, V: 0-1.0%, P≤0.01%, S≤0.01%, and the balance of Fe and unavoidable impurities.

7. The high carbon alloy steel of claim 6, wherein, The grain boundary carbide long axis size in the high-carbon alloy steel is less than or equal to 5 μm.

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