Method for efficient solid solution of coarse primary carbide in high-carbon alloy steel and product

Abstract

The invention relates to a method for high-efficiency solid solution of coarse primary carbide in high-carbon alloy steel and a product, and belongs to the field of high-carbon alloy steel production.The method comprises the steps that the thermodynamic equilibrium temperature A3 of complete phase change to austenite corresponding to nominal components of a high-carbon alloy steel casting blank or cast ingot is determined; the segregation degree of solute elements and the corresponding solidus temperature TSS are calculated according to the high-carbon alloy steel casting blank or ingot casting steel components and the cooling speed under the actual solidification working condition; electric pulse treatment is conducted within the temperature range of A3-TSS-200 DEG C in the cooling solidification process or the heating solid solution process of the high-carbon alloy steel casting blank or cast ingot, treatment is conducted for a period of time, and air cooling is conducted to the room temperature; and the obtained casting blank or cast ingot is heated to 900-1150 DEG C, heat preservation is conducted for 1-3 h, then thermal deformation is conducted, and air cooling is conducted to the room temperature. According to the method, electric pulse treatment is carried out in the hot-state casting blank / ingot cooling process or the cold-state casting blank / ingot heating solid solution process, and the primary carbide in the high-carbon alloy steel is subjected to efficient solid solution at the low temperature (smaller than or equal to 1150 DEG C) (the annealing time is smaller than or equal to 3 h).

Description

Technical Field

[0001] The invention belongs to the technical field of high carbon alloy steel production, and in particular relates to a method and a product for efficiently solid-solution of coarse primary carbides in high carbon alloy steel. Background Art

[0002] High carbon alloy steel includes tool steel, die steel, high carbon martensitic stainless steel and other steels with high carbon and alloy contents. They are widely used in tools, knives, molds, medical equipment, petrochemicals, aerospace and other fields to obtain high hardness, oxidation resistance and corrosion resistance at normal high temperatures. However, the common production technology bottleneck currently faced in the industrial production of this type of steel is due to its high carbon content and alloy element content, which leads to the formation of a large number of coarse primary alloy carbides due to segregation and eutectic reaction during the solidification process. This type of carbide is not only very harmful to the hot working performance and toughness, but also wastes the alloy elements added to the steel; and to eliminate these coarse primary carbides, the solidified ingot / bill needs to be heated to a sufficiently high temperature for a long time to keep warm, but due to the significant segregation of alloy elements and carbon during solidification, the solidus temperature of this type of steel in the segregation zone drops significantly. Excessive heating temperature will lead to 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 in turn requires further extension of the heating and holding time. The homogenization annealing time of the existing commercial large-size GCr15 bearing steel is generally more than 5 hours; this leads to a series of problems such as a significant reduction in production efficiency, severe oxidation, and coarse grains. Therefore, it is urgent to develop a technology that can efficiently dissolve coarse primary carbides in high carbon alloy steel at a lower temperature.

[0003] Electric pulse treatment is a non-equilibrium process that inputs electrical energy, thermal energy and strain energy into materials, inducing significant changes in the material's microstructure and mechanical properties. At present, electric pulse treatment has been widely used to refine the cast structure of metal materials, repair cracks, remove internal stress and promote the solid solution of the second phase. 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.]; Pulse current loading treatment before or after solution treatment of high-speed steel rolls can effectively refine the grains and promote the rapid and uniform precipitation of carbides, thereby shortening the heat treatment process [Li Guirong, Wang Hongming, Guo Ya, Fu De, Zhu Xiang, Electric pulse treatment method for improving heat treatment efficiency and organizational quality of high-speed steel rolls, authorization announcement number CN 103014299 B, authorization announcement date 2014.12.03; Zhang Jiatao, A method for preparing high-solubility ultrafine-grained high-speed steel using electric pulses, authorization announcement number CN 109825689B, authorization announcement date 2020.06.02]; In addition, electric pulse processing technology has also been used to regulate the second phase in the welding joints of two different materials, Q890 and 42CrMo steel, to improve the welding strength [Jiang Yanbin, Tan Yu, Li Zhou, Xu Guofu, Long Jiahui, A welding and electric pulse heat treatment process for dissimilar alloys, authorization announcement number CN 114406512 A, authorization announcement date 2022.04.29].

[0004] The pulse current promotes the dissolution of the second phase due to both thermodynamics and kinetics. In terms of thermodynamics, due to the difference in electrical conductivity between the second phase and the matrix, the pulse current loading process contributes additional phase transition Gibbs free energy, thereby reducing the dissolution temperature of the second phase; in terms of kinetics, the non-thermal effect of the pulse 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 the dissolution of the second phase. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a method and product for efficiently solid-solution of coarse primary carbides in high-carbon alloy steel, which are used to overcome 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. Determine the thermodynamic equilibrium temperature A3 of the complete phase transformation into austenite corresponding to the nominal composition of the high carbon alloy steel billet or ingot;

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

[0009] S3. A3~T during the cooling and solidification process or the heating and solution process of high carbon alloy steel billet or ingot SS Perform electric pulse treatment at -200℃, treat for a period of time and then air cool to room temperature;

[0010] S4. The ingot or billet obtained in S3 is heated to 900-1150°C and kept at this temperature for 1-3 hours, then heat-deformed and air-cooled to room temperature.

[0011] According to the aspects described above and any possible implementation methods, an implementation method is further provided, wherein the cooling and solidification process specifically includes: applying an electric pulse when the temperature of the high carbon alloy steel billet or ingot is cooled to a temperature range between A3 and Tss-200°C during the solidification process, so that the temperature of the high carbon alloy steel billet or ingot is maintained in the above temperature range; after the electric pulse treatment for 0.5 to 180 minutes, removing the pulse current, and then air cooling to room temperature.

[0012] According to the above aspects and any possible implementation, an implementation is further provided, wherein the temperature rising solid solution process comprises: heating the cold high carbon alloy steel billet by electric pulse treatment or electric pulse coupled with heat treatment, and raising the temperature to A3~T SS After heating to -200℃, keep warm for 0.5~180min and then air cool to room temperature.

[0013] According to the above aspects and any possible implementation, an implementation is further provided, 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 .

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

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

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

[0017] According to the aspects and any possible implementation methods described above, an implementation method is further provided, wherein the major axis size of the grain boundary carbides in the billet 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 billet or ingot before electric pulse treatment; or the major axis size of the grain boundary carbides after S1-S4 treatment is less than or equal to 1 / 10 of the maximum carbide size in the billet or ingot.

[0018] The present invention also provides a high-carbon alloy steel, which is prepared by the method described above, and the components of the high-carbon alloy steel include, 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 rest are Fe and inevitable impurities.

[0019] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the major axis size of the grain boundary carbides in the high carbon alloy steel is less than or equal to 5 μm.

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

[0021] The method for efficiently solid-solubilizing coarse primary carbides in high-carbon alloy steel of the present invention comprises the steps of: determining the thermodynamic equilibrium temperature A3 of complete phase transformation to austenite corresponding to the nominal composition of the high-carbon alloy steel billet or ingot; calculating the segregation degree of the solute element and the corresponding solidus temperature T according to the composition of the high-carbon alloy steel billet or ingot and the cooling rate under the actual solidification condition; SS ; During the cooling and solidification process or the heating and solution process of high carbon alloy steel billet or ingot, A3~T SS-200℃ temperature range, perform electric pulse treatment, treat for a period of time and air cool to room temperature; heat the resulting billet or ingot to 900-1150℃ and keep warm for 1-3h, then heat deform and air cool to room temperature. The present invention applies electric pulse treatment technology to the solidification cooling process and high-temperature solution process of high-carbon alloy steel, significantly refining the maximum carbide size in cast steel and forged steel. The present invention performs electric pulse treatment in the solidification process and solution treatment process of high-carbon alloy steel far below its solidus temperature range, significantly promoting the solidification of primary carbides and the diffusion of alloying elements, and ultimately shortening the homogenization time to within 3h, significantly improving production efficiency; in addition, compared with traditional solution treatment, the electric pulse treatment process of the present invention significantly refines the size of primary carbides in high-carbon alloy steel billets / ingots, forged steel and rolled products. The length of the grain boundary carbides in the high-carbon alloy steel billet / ingot prepared by the pulse technology of the present invention is ≤10μm or ≤1 / 5 of the maximum carbide size in the billet / ingot before electric pulse treatment; after forging or rolling, the maximum carbide size is ≤5μm or ≤1 / 10 of the maximum carbide size in the billet / ingot. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of the method of the present invention;

[0023] Figure 2 This is a schematic diagram of the microstructure of GCr15 bearing steel after the electric pulse treatment + thermal deformation of Example 1 of the present invention;

[0024] Figure 3 Schematic diagram of the microstructure of GCr15 bearing steel after conventional solution treatment + thermal deformation in Example 1 of the present invention;

[0025] Figure 4 This is a schematic diagram of the microstructure of high carbon stainless steel after the electric pulse treatment + thermal deformation of Example 2 of the present invention;

[0026] Figure 5 This is a schematic diagram of the microstructure of high carbon stainless steel after conventional solution treatment + thermal deformation in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] It should be clear that the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

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

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

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

[0033] S4. The ingot or billet obtained in S3 is heated to 900-1150°C and kept at this temperature for 1-3 hours, then heat-deformed and air-cooled to room temperature.

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

[0035] (1) Since the solid solubility of carbide-forming elements (including C, Cr, Mn, etc.) in the face-centered cubic structure phase is much higher than that in the body-centered cubic phase, the carbide solution treatment is generally above the complete austenitization temperature. Therefore, the design of the electric pulse solution treatment process first needs to determine by calculation the thermodynamic equilibrium temperature A3 at which ferrite is completely converted to austenite when the temperature is increased under the nominal composition of the treated steel.

[0036] (2) In order to prevent the temperature rise of the steel sample during the electric pulse treatment process from exceeding the solidus, 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 of the electric pulse treatment is set to A3 ~ T SS -200℃, electric pulse treatment can be performed as follows:

[0038] a. Cool down to A3~T during the solidification process of high carbon alloy steel SSElectric pulses are applied at a temperature range of -200°C, and the Joule heating effect of the pulse current is used to keep the temperature of the steel billet within the target temperature range to dissolve the carbides. After the electric pulse treatment for 0.5-180 minutes, the pulse current is removed, and the billet or ingot is air-cooled to room temperature;

[0039] b. Heat the cold high carbon alloy steel billet to A3~T by single electric pulse treatment or electric pulse + conventional heat treatment coupling method. SS A target temperature between -200℃, keep warm for 0.5~180min and then air cool to room temperature;

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

[0041] Preferably, before the steel billet is treated with pulse current, the impurities and contaminants on the surface of the steel billet are removed by machine grinding so that the steel billet can fully contact the electrode. The pulse generator is connected to the clamp at one end of the clamping device, and the clamp or contact at the other end contacts the steel billet, so that the two are connected so that the continuous electric pulse generated by it directly acts on the steel billet, and then the computer is used to control the output of the pulse current and change the current size, current frequency and other parameters of the electric pulse, and the instructions are transmitted to the pulse current generator through the network cable. Finally, the Joule heat effect and electrical effect of the electric pulse are used to control the carbide.

[0042] The present invention optimizes the preparation process of high carbon alloy steel by an electric pulse treatment method, and proposes a method for dissolving primary carbides in high carbon alloy steel from the aspects of current density, pulse frequency, duty cycle of electric pulses; solution temperature and time; thermal deformation temperature and reduction, so as to achieve the goals of simultaneously shortening the solution annealing time of high carbon alloy steel and refining primary carbides.

[0043] Preferably, in step (4), the thermal deformation temperature ranges from 800 to 1100° C., and the deformation amount ranges from 10 to 95%.

[0044] Preferably, the total processing time of step (3) and step (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 the present invention can be a sample steel prepared in a laboratory or a large-scale commercial product prepared by a steel enterprise.

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

[0047] The present invention also provides a high-carbon alloy steel, which is prepared by the electric pulse treatment method of the present invention.

[0048] According to the above aspects and any possible implementation, an implementation is further provided, wherein the composition of the high carbon alloy steel includes, 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 rest is Fe and unavoidable impurities. Wherein, the major axis size of the grain boundary carbides in the high carbon alloy steel is less than or equal to 5 μm.

[0049] The following specific embodiments are used to prove it:

[0050] In the following embodiments of the present invention, scanning electron microscope and optical microscope are used to observe the microstructure. The embodiments of the present invention follow the standard metallographic preparation method: 240 mesh, 600 mesh, 1000 mesh and 2000 mesh sandpaper are used to grind the surface of the bearing steel perpendicular to the rolling direction; water-soluble diamond grinding paste is used for polishing. When observing the microstructure of the electric pulse treated sample, a 4% volume fraction nitric acid alcohol solution is used for corrosion at room temperature, and the corrosion time is 5-15s.

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

[0052] (1) Using ThermalCalc software, it was calculated that the thermodynamic equilibrium temperature at which all ferrite in the studied high carbon stainless steel is converted to austenite is 747°C;

[0053] (2) The cooling rate of the solidification process of the small square billet continuous casting is generally between 0.5 and 1 °C / s. The "Schei1 solidification process simulation" module in the ThermalCalc software is used to simulate the non-equilibrium solidification process of the research steel, and the average solidus temperature of the research steel in the above cooling rate range is 1308 ± 5 °C;

[0054] (3) Based on the size and physical property parameters of the ingot to be processed, a pulse current loading device capable of applying the electric pulse process parameters of the present invention to both sides of the ingot is designed and installed.

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

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

[0057] - 2 , the temperature of the ingot is maintained between 650 and 1000°C. After 10 minutes of electric pulse treatment, the pulse current is removed and the ingot is air-cooled to room temperature.

[0058] (5) The continuous casting slab obtained in step (3) is heated to 1100°C by conventional heating method.

[0059] ℃ for 2h, and then hot rolled to a round billet with a diameter of 75mm.

[0060] Figure 2 The SEM image of the microstructure of GCr15 rolled steel prepared by the above method. It can be seen that the microstructure of the prepared steel is composed of lamellar pearlite, and no significant network carbides are found on the grain boundaries; Figure 3 The microstructure of GCr15 bearing steel rolled products prepared by traditional process at the same solution temperature can be seen from the presence of a large number of coarse network carbides on the grain boundaries, with a short axis length of 0.5 to 1.5 μm and a long axis length of up to 50 μm. The comparative experiment shows that the electric pulse treatment technology of the present invention can effectively dissolve and break the coarse network carbides in high carbon chromium bearing steel.

[0061] Example 2: The electric pulse treatment technology of the present invention is used to treat a high carbon stainless steel Fe-1.0C-14Cr-0.3Si-0.3Mn-1Mo-1W (wt.%) cold billet mold casting ingot, which has a cross section of 60mm×60mm and a length of 0.5m, including the following process steps:

[0062] (1) Using ThermalCalc software, it was calculated that the thermodynamic equilibrium temperature at which all ferrite in the studied high carbon stainless steel is converted to austenite is 815°C;

[0063] (2) The cooling rate of the solidification of the research mold casting is generally about 1℃ / s. The "Schei1 solidification process simulation" module in the ThermalCalc software is used to simulate the non-equilibrium solidification process of the research steel, and the average solidus temperature of the research steel in the above cooling rate range is 1229℃;

[0064] (3) According to the size and physical property parameters of the ingot to be processed, a device for loading pulse current of the process of the present invention is designed and installed to apply the pulse current of the process of the present invention to both ends of the ingot during the heating process of the ingot.

[0065] (4) The cold mold casting blank is heated by electric pulse auxiliary heating, with the target temperature being 1000°C. In the specific implementation process, a large box furnace is used for heating, and pulse current is applied to both ends of the ingot. The pulse frequency of the electric pulse is 1000 Hz, the duty cycle is 8%, and the current density is 25 A·mm -2 . The temperature was raised in a box furnace and under the action of pulse current thermal effect, kept at 1000℃ for 1h, and then air-cooled to room temperature;

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

[0067] Figure 4 This is the OM image of the microstructure of the high carbon stainless steel rolled material prepared above. It can be seen that no coarse carbides connected into a network are found on the grain boundaries of the prepared steel, and the maximum long axis size of the carbides on the grain boundaries is less than 5μm, which means that the pulse current dissolves the carbides with a long axis size greater than 5μm in the high carbon alloy steel; Figure 5 The microstructure of the rolled product prepared by the traditional solution + rolling process. It can be seen that there are a large number of coarse carbides on the grain boundaries, and the maximum long axis size reaches 50μm. This shows that the electric pulse treatment technology in the present invention can effectively dissolve the coarse primary carbides in high-carbon stainless steel.

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

[0069] (1) Using ThermalCalc software, it was calculated that the thermodynamic equilibrium temperature at which all ferrite in the studied high carbon stainless steel is converted to austenite is 813°C;

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

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

[0072] (4) The ingot obtained in step (3) is heated to 1000-1050°C by electric pulse assisted heating and kept at this 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·mm -2 The ingot after the electric pulse assisted heating was hot rolled into a 10 mm thick sheet through 5 passes.

[0073] The metallographic method was used to count the size of coarse grain boundary carbides in the as-cast structure of Cr12Mo1V1 die steel and the thin plate structure after treatment by the present invention. It was found that the average long axis size of the carbides in the ingot was 65±6μm, and the average long axis size of the carbides in the thin plate after treatment by the present invention was 6±4μm, which was less than 1 / 10 of the long axis size of the carbides before treatment.

[0074] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0075] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for efficiently dissolving coarse primary carbides in high-carbon alloy steel, characterized in that: The method comprises the steps of: S1. Determine the thermodynamic equilibrium temperature A3 of the complete phase transformation into austenite corresponding to the nominal composition of the high carbon alloy steel billet or ingot; S2. Calculate the segregation degree of solute elements and the corresponding solidus temperature T according to the composition of high carbon alloy steel billet or ingot and the cooling rate under actual solidification conditions. SS ; S3. A3~T during the cooling and solidification process or the heating and solution process of high carbon alloy steel billet or ingot SS Electric pulse treatment is performed at a temperature range of -200°C for a period of time and then air-cooled to room temperature; S4. The ingot or billet obtained in S3 is heated to 900-1150°C and kept at this temperature for 1-3 hours, then heat-deformed and air-cooled to room temperature.

2. The method according to claim 1, characterized in that The cooling and solidification process specifically includes: applying electric pulses when the temperature of the high carbon alloy steel billet or ingot is cooled to a temperature range between A3 and Tss-200°C during the solidification process, so that the temperature of the high carbon alloy steel billet or ingot is maintained in the above temperature range; after the electric pulse treatment for 0.5 to 180 minutes, removing the pulse current and then air cooling to room temperature.

3. The method according to claim 1, characterized in that The temperature rise solid solution process comprises: heating the cold high carbon alloy steel billet by electric pulse treatment or electric pulse coupled with heat treatment to a temperature of A3 to T SS After heating to -200℃, keep warm for 0.5~180min and then air cool to room temperature.

4. The method according to claim 1, characterized in that 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 .

5. The method according to claim 4, characterized in that The pulse frequency is 1000 Hz, the duty cycle is 10%, and the current density is 15 A·mm -2 .

6. The method according to claim 4, characterized in that The pulse frequency is 1000 Hz, the duty cycle is 8%, and the current density is 25 A·mm -2 .

7. The method according to claim 1, characterized in that The parameters of the electric pulse are: pulse frequency 0-2000 Hz, duty cycle 0-15% and current density 0-200 A·mm -2 .

8. The method according to claim 7, characterized in that After S1-S3 treatment, the long axis size of the grain boundary carbides in the billet or ingot is less than or equal to 10μm or less than or equal to 1 / 5 of the maximum carbide size in the billet or ingot before electric pulse treatment; or after S1-S4 treatment, the long axis size of the grain boundary carbides is less than or equal to 1 / 10 of the maximum carbide size in the billet or ingot.

9. A high carbon alloy steel, characterized in that: The high carbon alloy steel is prepared by the method described in any one of claims 1 to 8, and the components of the high carbon alloy steel include, 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 rest are Fe and unavoidable impurities.

10. The high carbon alloy steel according to claim 9, characterized in that: The major axis size of the grain boundary carbides in the high carbon alloy steel is less than or equal to 5 μm.

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