A high-alloy steel electroslag ingot and a method of homogenizing the same

Abstract

A high-alloy steel electroslag ingot and its homogenization method are provided, comprising the following steps: S1, electroslag ingot pretreatment: removing surface oxide scale and crack defects, and grinding to a surface roughness Ra≤6.3μm; S2, staged heating: heating to 800-900℃ at a rate ≤100℃ / h and holding for 2-6h; heating to 1000-1100℃ at a rate ≤100℃ / h and holding for 2-6h; heating to 1200-1300℃ at a rate ≤150℃ / h and holding for 10h. -20h; S3, Stepped cooling: Turn off the heating device and cool with the furnace to 800-1000℃, hold for 2-6h; cool to 500-650℃ at a rate of ≤50℃ / h, hold for 2-6h; open the furnace door and introduce cooling air at a speed of 0.5-3m / s to cool to room temperature, obtaining homogenized high-alloy steel electroslag ingots; S4, Post-homogenization testing: the relative standard deviation of each alloying element is ≤5%; the average grain size is ≤10μm; the Brinell hardness fluctuation range is ≤15HBW. This invention eliminates component segregation, refines grain structure, optimizes process parameters, is highly efficient and energy-saving, easy to promote, and has strong practicality.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment technology for iron-based alloys, specifically relating to a high-alloy steel electroslag ingot and its homogenization method. Background Technology

[0002] High-alloy steel possesses high strength, high toughness, and excellent thermal fatigue properties, making it widely used in die-casting molds, forging molds, and other fields. Electroslag remelting is a key process for preparing high-quality high-alloy steel billets (electroslag ingots), effectively removing inclusions and refining grains. However, due to factors such as uneven solidification rate and differences in elemental specific gravity during the electroslag remelting process, high-alloy steel electroslag ingots still face the following technical challenges:

[0003] Compositional segregation: The core of the electroslag ingot is prone to enrichment of alloying elements such as carbon, chromium, and molybdenum, while the edge areas are depleted of these elements, resulting in significant differences in mechanical properties between different parts of the billet; Inhomogeneous structure: Coarse columnar crystals and carbide agglomeration areas are easily formed inside the electroslag ingot, which can easily lead to cracking defects during subsequent forging and reduce the service life of the final die; Defects of existing homogenization methods: Traditional homogenization often adopts "single high temperature and long-term holding" (such as holding at 1100-1150℃ for 20-40h), which is not only energy-intensive and inefficient, but also prone to excessive grain growth, which weakens the mechanical properties of the billet.

[0004] Therefore, there is an urgent need for a homogenization method that can efficiently solve the problem of uneven composition and microstructure in high-alloy steel electroslag ingots while also refining grains, in order to improve the subsequent processing performance of high-alloy steel and the quality of the final product. To this end, the following improved technical solution is proposed. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a high-alloy steel electroslag ingot and its homogenization method, which solves the technical problems of internal component segregation, uneven microstructure, high energy consumption and low production efficiency of high-alloy steel electroslag ingots in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a homogenization method for high-alloy steel electroslag ingots, comprising the following steps:

[0007] S1. Pretreatment of electroslag ingots: Remove the surface oxide scale and crack defects of high alloy steel electroslag ingots, and grind the high alloy steel electroslag ingots until their surface roughness Ra≤6.3μm.

[0008] S2. Staged heating: First heating stage: Heat to 800-900℃ at a rate of ≤100℃ / h, and hold for 2-6 hours; Second heating stage: Heat to 1000-1100℃ at a rate of ≤100℃ / h, and hold for 2-6 hours; Third heating stage: Heat to 1200-1300℃ at a rate of ≤150℃ / h, and hold for 10-20 hours.

[0009] S3. Step-by-step cooling: First cooling stage: turn off the heating device and cool with the furnace to 800-1000℃, hold for 2-6 hours; Second cooling stage: cool to 500-650℃ at a rate of ≤50℃ / h, hold for 2-6 hours; Third cooling stage: open the furnace door and introduce cooling air with a wind speed of 0.5-3m / s to cool to room temperature to obtain homogenized high alloy steel electroslag ingots.

[0010] S4. Post-homogenization testing: Sampling: Samples are taken from three locations: the edge, half radius, and center of the high-alloy steel electroslag ingot, to prepare metallographic and compositional analysis samples; Testing indicators: The distribution deviation of alloying elements is tested, and the relative standard deviation of each alloying element is required to be ≤5%; the grain size is observed, and the average grain size is required to be ≤10μm; the Brinell hardness is tested, and the hardness fluctuation range is required to be ≤15HBW.

[0011] In the above technical solution, the preferred method is: in step S1, the diameter of the high alloy steel electroslag ingot is 500-1500mm; the high alloy steel electroslag ingot is polished with sandpaper until its surface roughness Ra≤6.3μm.

[0012] In the above technical solution, the preferred step is to detect the distribution deviation of alloying elements, wherein the alloying elements include C, Cr, Mo, V, Si, and Mn.

[0013] In the above technical solution, the preferred method is to use a direct-reading spectrometer to detect the distribution deviation of alloying elements in step S4; to use a metallographic microscope to observe the grain size; and to use a hardness tester to detect the Brinell hardness.

[0014] This invention also claims protection for a high-alloy steel electroslag ingot, wherein the high-alloy steel electroslag ingot is the high-alloy steel electroslag ingot used in any of the preceding homogenization methods, and the chemical composition (wt%) of the high-alloy steel electroslag ingot is: C 0.35-0.42%, Si 0.8-1.2%, Mn 0.3-0.5%, Cr 5.0-5.5%, Mo 1.2-1.4%, V 0.9-1.1%, O ≤0.002%, N 0.02-0.06%, H ≤0.0002%, with the balance being iron and unavoidable impurities.

[0015] The beneficial effects of this invention are:

[0016] 1. This invention effectively eliminates internal component segregation in electroslag ingots, ensuring a uniform distribution of alloying elements of ≥90%; this invention effectively refines the grain structure of electroslag ingots, controlling the average grain size to below 10μm; this invention optimizes process parameters, shortens holding time, reduces energy consumption, and avoids excessive grain growth.

[0017] 2. This invention achieves full diffusion of alloying elements through "staged heating + precise heat preservation". The element distribution deviation is reduced from 10-15% in traditional methods to ≤5%, which solves the problems of forging cracking and performance differences caused by component segregation in electroslag ingots and significantly improves the uniformity of composition.

[0018] 3. The stepped cooling combined with multi-stage heat preservation of this invention not only refines the grains, making the average grain size reach at least 9.5, but also promotes the uniform precipitation of carbides. The hardness fluctuation range of the electroslag ingot is ≤15HBW, and the service life after subsequent mold processing can be increased by 20%-30%, and the microstructure and mechanical properties are optimized.

[0019] 4. Compared with the traditional homogenization process, the total heat preservation time of this method is 14-32 hours, and the energy consumption is reduced by controlling the heating rate, resulting in a 15-20% increase in production efficiency. The process is highly efficient and energy-saving.

[0020] 5. This invention requires no special equipment and can be implemented directly in existing bogie-type heating furnaces, making it easy to promote industrialization and highly practical. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a heat treatment curve diagram of the homogenization of high alloy steel electroslag ingots according to the present invention.

[0023] Figure 2 This is a micrograph of the high-alloy steel electroslag ingot after homogenization according to the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] A method for homogenizing high-alloy steel electroslag ingots includes the following steps:

[0027] S1. Pretreatment of electroslag ingots: Remove the surface oxide scale and crack defects of high alloy steel electroslag ingots, and grind the high alloy steel electroslag ingots to a surface roughness Ra=6.3μm.

[0028] In the above embodiments, preferably: in step S1, the diameter of the high-alloy steel electroslag ingot is 1500mm; the high-alloy steel electroslag ingot is polished with sandpaper until its surface roughness Ra=6.3μm.

[0029] S2, phased heating:

[0030] The first heating stage: the temperature is increased to 900℃ at a rate of ≤100℃ / h and held for 6 hours. The purpose of this stage is to eliminate the internal thermal stress of the electroslag ingot and avoid cracking during subsequent high-temperature heating.

[0031] The second heating stage: the temperature is increased to 1100℃ at a rate of ≤100℃ / h and held for 6h. This stage promotes the initial diffusion of low-melting-point alloying elements (such as molybdenum and vanadium) and alleviates mild segregation.

[0032] The third heating stage: the temperature is increased to 1300℃ at a rate of ≤150℃ / h and held for 20h. This stage is the core diffusion stage, which promotes the uniform distribution of major elements such as carbon and chromium, while controlling the heating rate to avoid rapid grain growth.

[0033] S3, stepped cooling:

[0034] First cooling stage: Turn off the heating device and cool the furnace to 1000℃, then hold for 6 hours; this stage promotes uniform precipitation of carbides and avoids excessive cooling that could lead to carbide aggregation.

[0035] Second cooling stage: Cool to 650℃ at a rate of ≤50℃ / h, hold for 6h to further release structural stress and stabilize grain boundary structure.

[0036] The third cooling stage: Open the furnace door and introduce cooling air at a speed of 3m / s to cool to room temperature, thereby obtaining homogenized high-alloy steel electroslag ingots.

[0037] S4. Post-homogenization detection:

[0038] Sampling: Samples were taken from three locations: the edge, half radius, and the center of the high-alloy steel electroslag ingot, to prepare metallographic and compositional analysis samples.

[0039] Testing indicators: The distribution deviation of alloying elements was detected using a direct-reading spectrometer. The alloying elements include C, Cr, Mo, V, Si, and Mn, and the relative standard deviation of each element is ≤5%. The grain size was observed using a metallographic microscope, and the average grain size is ≤10μm. The Brinell hardness was tested using a hardness tester, and the hardness fluctuation range is ≤15HBW.

[0040] Example 2:

[0041] A method for homogenizing high-alloy steel electroslag ingots includes the following steps:

[0042] S1. Pretreatment of electroslag ingots: Remove the surface oxide scale and crack defects of high alloy steel electroslag ingots, and grind the high alloy steel electroslag ingots to a surface roughness Ra=3.2μm.

[0043] In the above embodiments, preferably: in step S1, the diameter of the high-alloy steel electroslag ingot is 800 mm; the high-alloy steel electroslag ingot is polished with sandpaper until its surface roughness Ra = 3.2 μm.

[0044] S2, phased heating:

[0045] The first heating stage: heat to 850℃ at a rate of ≤100℃ / h and hold for 4 hours. The purpose of this stage is to eliminate the internal thermal stress of the electroslag ingot and avoid cracking during subsequent high-temperature heating.

[0046] The second heating stage: the temperature is increased to 1050℃ at a rate of ≤100℃ / h and held for 4h. This stage promotes the initial diffusion of low-melting-point alloying elements (such as molybdenum and vanadium) and alleviates mild segregation.

[0047] The third heating stage: the temperature is increased to 1250℃ at a rate of ≤150℃ / h and held for 15h. This stage is the core diffusion stage, which promotes the uniform distribution of major elements such as carbon and chromium. At the same time, the rapid growth of grains is avoided by controlling the heating rate.

[0048] S3, stepped cooling:

[0049] First cooling stage: Turn off the heating device and cool the furnace to 900℃, then hold for 4 hours; this stage promotes uniform precipitation of carbides and avoids excessive cooling that could lead to carbide aggregation.

[0050] Second cooling stage: Cool to 600℃ at a rate of ≤50℃ / h, hold for 4h to further release structural stress and stabilize grain boundary structure.

[0051] The third cooling stage: Open the furnace door and introduce cooling air at a speed of 2m / s to cool to room temperature, thereby obtaining homogenized high-alloy steel electroslag ingots.

[0052] S4. Post-homogenization detection:

[0053] Sampling: Samples were taken from three locations: the edge, half radius, and the center of the high-alloy steel electroslag ingot, to prepare metallographic and compositional analysis samples.

[0054] Testing indicators: The distribution deviation of alloying elements was detected using a direct-reading spectrometer. The alloying elements include C, Cr, Mo, V, Si, and Mn, and the relative standard deviation of each element is ≤5%. The grain size was observed using a metallographic microscope, and the average grain size is ≤10μm. The Brinell hardness was tested using a hardness tester, and the hardness fluctuation range is ≤15HBW.

[0055] Example 3:

[0056] A method for homogenizing high-alloy steel electroslag ingots includes the following steps:

[0057] S1. Pretreatment of electroslag ingots: Remove the surface oxide scale and crack defects of high alloy steel electroslag ingots, and grind the high alloy steel electroslag ingots until their surface roughness Ra < 3.2 μm.

[0058] In the above embodiments, preferably: in step S1, the diameter of the high-alloy steel electroslag ingot is 500 mm; the high-alloy steel electroslag ingot is polished with sandpaper until its surface roughness a < 3.2 μm.

[0059] S2, phased heating:

[0060] The first heating stage: heat to 800℃ at a rate of ≤100℃ / h and hold for 2 hours. The purpose of this stage is to eliminate the internal thermal stress of the electroslag ingot and avoid cracking during subsequent high-temperature heating.

[0061] The second heating stage: the temperature is increased to 1000℃ at a rate of ≤100℃ / h and held for 2h. This stage promotes the initial diffusion of low melting point alloying elements (such as molybdenum and vanadium) and alleviates mild segregation.

[0062] The third heating stage: the temperature is increased to 1200℃ at a rate of ≤150℃ / h and held for 10h. This stage is the core diffusion stage, which promotes the uniform distribution of major elements such as carbon and chromium. At the same time, the rapid growth of grains is avoided by controlling the heating rate.

[0063] S3, stepped cooling:

[0064] First cooling stage: Turn off the heating device and cool the furnace to 800℃, then hold for 2 hours; this stage promotes uniform precipitation of carbides and avoids excessive cooling that could lead to carbide aggregation.

[0065] Second cooling stage: Cool to 500℃ at a rate of ≤50℃ / h, hold for 2h to further release structural stress and stabilize grain boundary structure.

[0066] The third cooling stage: Open the furnace door and introduce cooling air at a speed of 0.5 m / s to cool to room temperature, thereby obtaining homogenized high-alloy steel electroslag ingots.

[0067] S4. Post-homogenization detection:

[0068] Sampling: Samples were taken from three locations: the edge, half radius, and the center of the high-alloy steel electroslag ingot, to prepare metallographic and compositional analysis samples.

[0069] Testing indicators: The distribution deviation of alloying elements was detected using a direct-reading spectrometer. The alloying elements include C, Cr, Mo, V, Si, and Mn, and the relative standard deviation of each element is ≤5%. The grain size was observed using a metallographic microscope, and the average grain size is ≤10μm. The Brinell hardness was tested using a hardness tester, and the hardness fluctuation range is ≤15HBW.

[0070] It should be noted that the homogenization method of this invention optimizes surface pretreatment to reduce defect interference. Staged heating and holding promote compositional homogenization. Stepped cooling control optimizes microstructure and properties. Multi-location sampling and rigorous testing ensure quality controllability. Overall process synergy enhances comprehensive performance.

[0071] Removing oxide scale and cracks, and polishing to a surface roughness Ra ≤ 6.3 μm, can eliminate the interference of surface defects on subsequent heating and cooling processes, avoiding crack propagation or component segregation caused by surface stress concentration. The surface quality of electroslag ingots directly affects the homogenization effect. Surface defects (such as oxide scale and cracks) can become the starting point for the accumulation of elements such as hydrogen and oxygen, leading to local component segregation or abnormal microstructure. Polishing can reduce such risks and provide a good foundation for homogenization annealing.

[0072] The process involves three stages: First, a low-temperature holding stage eliminates residual stress within the electroslag ingot, preventing deformation or cracking due to stress release. Second, a medium-temperature holding stage promotes the dissolution of second phases such as carbides, reducing component segregation. Third, a high-temperature holding stage (10-20 hours) allows for sufficient diffusion of alloying elements, achieving the goal of component homogenization. This staged heating gradually eliminates segregation: the low-temperature stage relieves stress, the medium-temperature stage dissolves the second phase, and the high-temperature stage promotes diffusion. The holding time is designed based on the diffusion coefficient of the alloying elements. For example, the atomic migration rate increases at high temperatures, and a long holding time ensures that component homogenization meets requirements (e.g., relative standard deviation of each element ≤5%).

[0073] The cooling process involves three stages: the first stage, slow cooling to reduce thermal stress and prevent crack formation; the second stage, controlling the cooling rate to promote uniform carbide precipitation and refine grains; and the third stage, rapid cooling to fix the homogenized microstructure and prevent coarsening of the second phase. The cooling rate is crucial to microstructure evolution. For example, excessively rapid cooling may lead to martensitic transformation and stress concentration, while excessively slow cooling may result in coarse grains. Stepped cooling controls the rate in stages, balancing microstructure refinement with stress release. The air-cooling stage (0.5-3 m / s) accelerates cooling to room temperature while avoiding microstructure differences caused by uneven cooling rates, ensuring a hardness fluctuation range ≤15 HBW.

[0074] Sampling locations include the edge, half radius, and center of the electroslag ingot, comprehensively assessing the composition and microstructure homogeneity. Compositional deviation is ensured through chemical analysis, guaranteeing a relative standard deviation of ≤5% for each element, meeting the compositional accuracy requirements of high-alloy steel. Grain size is required to be ≤10μm on average to avoid performance degradation (such as reduced toughness) due to coarse grains. Hardness fluctuation is controlled within ≤15HBW to ensure consistent material properties. The composition and microstructure homogeneity of the electroslag ingot directly affect its mechanical properties. For example, compositional segregation may lead to localized hardness anomalies, and coarse grains may reduce fatigue resistance. Rigorous testing ensures that the homogenization effect meets the requirements of high-end applications.

[0075] This process achieves comprehensive optimization of the composition, microstructure, and properties of electroslag remelting ingots through surface treatment, coordinated control of heating-holding-cooling, and multi-index detection. Electroslag remelting already possesses advantages in removing inclusions and refining grains, while the homogenization treatment of this invention further eliminates component segregation, improving the purity and uniformity of the material. For example, the carbide inhomogeneity in the electroslag remelted steel ingot can be reduced by 3-4 levels, while the homogenization treatment can further refine the grains to ≤10μm, significantly improving the strength and toughness of the material.

[0076] In summary, the homogenization method for high-alloy steel electroslag ingots of this invention achieves the goals of compositional homogenization, microstructure refinement, and performance stabilization through surface pretreatment, staged temperature control, stepped cooling, and rigorous testing. It eliminates surface defects and reduces the sources of compositional segregation; staged heating and holding promote the diffusion of alloying elements; stepped cooling controls microstructure evolution, avoiding stress and cracking; multi-location sampling and rigorous testing ensure quality controllability; and the overall process synergistically improves the comprehensive performance of the material, meeting the needs of high-end applications.

[0077] This invention also claims protection for a high-alloy steel electroslag ingot, wherein the high-alloy steel electroslag ingot is the high-alloy steel electroslag ingot used in any of the preceding homogenization methods, and the chemical composition (wt%) of the high-alloy steel electroslag ingot is: C 0.35-0.42%, Si 0.8-1.2%, Mn 0.3-0.5%, Cr 5.0-5.5%, Mo 1.2-1.4%, V 0.9-1.1%, O ≤0.002%, N 0.02-0.06%, H ≤0.0002%, with the balance being iron and unavoidable impurities.

[0078] Example 1: The chemical composition (wt%) of the high-alloy steel electroslag ingot containing C, Cr, Mo, V, Si, and Mn is shown in Table 1:

[0079] Table 1. Chemical composition analysis results of Example 1

[0080]

[0081] Example 2: The chemical composition (wt%) of the high-alloy steel electroslag ingot containing C, Cr, Mo, V, Si, and Mn is shown in Table 2.

[0082] Table 2. Chemical composition analysis results of Example 2

[0083]

[0084] Example 3: The chemical composition (wt%) of C, Cr, Mo, V, Si, and Mn in the high-alloy steel electroslag ingot is shown in Table 3:

[0085] Table 3. Results of chemical composition analysis in Example 3

[0086]

[0087] It should be noted that the composition of this invention is precisely designed to meet high-performance requirements. Extremely low gas content enhances purity and toughness. High compositional uniformity reduces performance fluctuations. Refined grains and stable microstructure improve overall performance. Synergistic process and composition reduce manufacturing costs.

[0088] Among them, C (0.35-0.42%): Medium carbon content balances strength and toughness. Carbon is a strengthening element, but too much carbon can lead to increased brittleness. This range ensures that the material obtains a martensitic structure after quenching, while subsequent homogenization treatment refines the grains and avoids the precipitation of coarse carbides. Cr (5.0-5.5%), Mo (1.2-1.4%), V (0.9-1.1%): Multi-element alloying improves corrosion resistance, high-temperature strength, and fatigue resistance. Cr improves oxidation resistance, Mo enhances high-temperature stability, and V refines grains and suppresses temper brittleness. The synergistic effect of these three elements makes the material suitable for extreme working conditions (such as high-temperature and corrosive environments). Si (0.8-1.2%), Mn (0.3-0.5%): Deoxidizers and strengthening elements. Si deoxidizes and improves the elastic limit, while Mn deoxidizes and strengthens through solid solution. At the same time, the Mn content is controlled to avoid banded structures caused by segregation. Multi-element alloying significantly improves the overall performance of materials through solid solution strengthening, second-phase strengthening (such as carbides), and grain boundary strengthening mechanisms. For example, the addition of Cr-Mo-V composites can form fine, dispersed carbides, which hinder dislocation movement and improve strength and hardness.

[0089] Specifically, O ≤ 0.002%: Ultra-low oxygen content reduces non-metallic inclusions, preventing them from becoming crack initiators and significantly improving fatigue life and toughness. N (0.02-0.06%): Appropriate amounts of nitrogen can form nitrides (such as VN, CrN), refining grains and increasing strength, but excessive amounts can lead to aging brittleness. This range balances strengthening effects and toughness. H ≤ 0.0002%: Extremely low hydrogen content prevents hydrogen-induced cracking, making it particularly suitable for high-pressure and low-temperature environments. This composition design optimizes gas content, ensuring material purity meets the requirements of high-end applications.

[0090] The homogenization method and composition design work synergistically to ensure that the compositional deviation (e.g., Cr, Mo, etc.) at the edge, half radius, and core of the electroslag ingot is ≤5%, avoiding local performance differences. Uniform composition reduces quenching deformation, improves heat treatment stability, and ensures consistent performance in mass production. The stirring effect of the molten pool in electroslag remelting, combined with the staged heating and holding processes of the homogenization treatment in this invention, jointly promotes the diffusion of alloying elements.

[0091] The homogenization treatment resulted in an average grain size ≤10μm, significantly improving both strength and toughness. The fine-grained structure hinders crack propagation through grain boundary strengthening, while also improving low-temperature toughness. Grain refinement is a key approach to improving material properties. Reduced grain size significantly increases yield strength. Simultaneously, the fine-grained structure improves toughness, preventing brittle fracture caused by coarse grains.

[0092] In this process, the composition design takes into account both performance and cost. For example, expensive elements (such as Ni and Co) are avoided, and performance is optimized and material costs are reduced by adding Cr-Mo-V composites.

[0093] Table 4: Hardness Test Values

[0094]

[0095] In summary, this high-alloy steel electroslag ingot achieves high performance through precise composition design, extremely low gas content control, and synergistic homogenization processes: multi-element alloying enhances corrosion resistance, high-temperature strength, and fatigue resistance; high purity: ultra-low oxygen and hydrogen content reduces the risk of inclusions and cracks; high uniformity: compositional deviation ≤5%, avoiding local performance differences; fine-grained structure: average grain size ≤10μm, improving strength and toughness; and low cost: synergistic optimization of process and composition reduces manufacturing costs.

[0096] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for homogenizing high-alloy steel electroslag ingots, characterized in that, Includes the following steps: S1. Pretreatment of electroslag ingots: Remove the surface oxide scale and crack defects of high alloy steel electroslag ingots, and grind the high alloy steel electroslag ingots until their surface roughness Ra≤6.3μm; S2. Staged heating: First heating stage: Heat to 800-900℃ at a rate of ≤100℃ / h, and hold for 2-6 hours; Second heating stage: Heat to 1000-1100℃ at a rate of ≤100℃ / h, and hold for 2-6 hours; The third heating stage: heat up to 1200-1300℃ at a rate of ≤150℃ / h, and hold for 10-20h; S3, Stepped cooling: First cooling stage: Turn off the heating device and cool the furnace to 800-1000℃, then hold for 2-6 hours; Second cooling stage: Cool to 500-650℃ at a rate of ≤50℃ / h, and hold for 2-6 hours; The third cooling stage: Open the furnace door and introduce cooling air with a wind speed of 0.5-3m / s to cool to room temperature and obtain homogenized high alloy steel electroslag ingots; S4. Post-homogenization testing: Sampling: Samples are taken from three locations on the edge, at half the radius, and at the center of the high-alloy steel electroslag ingot to prepare metallographic and compositional analysis samples; Testing indicators: The distribution deviation of alloying elements is tested, and the relative standard deviation of each alloying element is required to be ≤5%; Observe the grain size, and the average grain size should be ≤10μm; test the Brinell hardness, and the hardness fluctuation range should be ≤15HBW.

2. The homogenization method according to claim 1, characterized in that: Step S1: The diameter of the high-alloy steel electroslag ingot is 500-1500mm; the high-alloy steel electroslag ingot is polished with sandpaper until its surface roughness Ra≤6.3μm.

3. The homogenization method according to claim 1, characterized in that: Step S4 detects the distribution deviation of alloying elements, including C, Cr, Mo, V, Si, and Mn.

4. The homogenization method according to claim 1, characterized in that: Step S4 involves using a direct-reading spectrometer to detect the distribution deviation of alloying elements; using a metallographic microscope to observe the grain size; and using a hardness tester to detect the Brinell hardness.

5. A high-alloy steel electroslag ingot, characterized in that: The high-alloy steel electroslag ingot is the high-alloy steel electroslag ingot used in the homogenization method according to any one of claims 1-4, and the chemical composition (wt%) of the high-alloy steel electroslag ingot is: C 0.35-0.42%, Si 0.8-1.2%, Mn 0.3-0.5%, Cr 5.0-5.5%, Mo 1.2-1.4%, V 0.9-1.1%, O≤0.002%, N 0.02-0.06%, H≤0.0002%, with the balance being iron and unavoidable impurities.

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