A 4341e high speed steel and a method of making the same

Abstract

The application relates to the technical field of alloy materials, in particular to a 4341E high-speed steel and a preparation method thereof. The high-speed steel is characterized in that Ti, B and N elements are introduced for ternary micro-alloying and synergistic modification on the basis of a W-Mo-V-Co component system, nanoscale particles generated in-situ by Ti-N are used as heterogeneous cores to significantly refine grains, the grain boundary is strengthened by the grain boundary segregation effect of boron elements, and the reticular carbide is effectively broken. The obtained steel material realizes perfect matching of high hardness, excellent red hardness and excellent impact toughness, solves the problem that the strength and toughness of traditional high-speed steel are difficult to be compatible, and is particularly suitable for manufacturing high-performance cutting tools, cold and hot precision dies and high-temperature wear-resistant parts.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a 4341E high-speed steel and its preparation method. Background Technology

[0002] High-speed steel (HSS), a high-carbon, high-alloy tool steel, is widely used in the manufacture of core industrial components such as cutting tools, hot and cold work dies, and high-temperature bearings due to its high hardness, high wear resistance, and excellent red hardness. Among the many HSS grades, 4341 series high-speed steel (W4Mo3Cr4V) not only retains the high thermal stability of tungsten-based high-speed steel but also possesses the toughness advantages of molybdenum-based high-speed steel, while having relatively controllable production costs, thus occupying a significant market share in the civilian tool and mid-range machining sectors.

[0003] However, with the rapid development of modern manufacturing towards high-speed, high-precision, and difficult-to-machine material cutting, the performance bottlenecks of 4341 high-speed steel produced by traditional smelting processes have gradually become apparent. Firstly, during the solidification process of traditional 4341 steel, alloying elements are prone to microscopic segregation, resulting in coarse network or fishbone-like distribution of primary eutectic carbides (such as M2C and M6C). This coarse carbide network severely disrupts the continuity of the austenite matrix, making the material highly susceptible to crack initiation during subsequent hot deformation processing and service, leading to premature chipping or fracture failure of the cutting tools.

[0004] To improve carbide morphology and enhance toughness, the industry typically employs electroslag remelting (ESR) technology for secondary refining of steel ingots. While conventional ESR effectively removes impurities such as sulfur and phosphorus and refines inclusions, its slow cooling rate often leads to excessively long grain dwell times at high temperatures, resulting in abnormal grain growth. Coarse austenite grains not only reduce the material's impact toughness but also weaken its ability to retain hardness at high temperatures (i.e., red hardness).

[0005] In addition, in pursuit of higher red hardness, some technical solutions attempt to achieve precipitation hardening by significantly increasing the content of precious alloying elements such as tungsten and vanadium. This not only leads to a sharp increase in raw material costs, but also further exacerbates the problem of carbide segregation, resulting in a technical contradiction where high alloys lead to low toughness and low alloys lead to low red hardness.

[0006] While existing microalloying technologies have attempted to introduce elements such as titanium and niobium to refine grains, in actual industrial production, the lack of precise control over the timing, form, and synergistic mechanism of trace element addition often leads to new problems such as unstable yield, coarsening of nitrogen-containing inclusions, and grain boundary embrittlement. For example, titanium is easily oxidized to form large TiO2 inclusions, which impairs the matrix properties; while the addition of nitrogen alone, if not properly controlled, can easily generate pores that lead to microcracks.

[0007] Therefore, how to simultaneously achieve ultra-fine grains, dispersed carbides, and strengthened grain boundaries in 4341 high-speed steel through precise composition design and metallurgical process control without significantly increasing the cost of precious alloys, and break the performance constraint of the trade-off between hardness and toughness, has become a key technical problem that urgently needs to be solved in the current high-speed steel manufacturing field. Summary of the Invention

[0008] In view of this, the purpose of this invention is to propose a 4341E high-speed steel and its preparation method, so as to solve the problem of how to simultaneously achieve high hardness and high toughness under a low-cost 4341 composition system.

[0009] To achieve the above objectives, the present invention provides a 4341E high-speed steel, wherein the chemical composition of the 4341E high-speed steel, by mass percentage, comprises C: 0.90%-1.00%, Si: 0.80%-1.20%, Mn: 0.20%-0.50%, W: 1.8%-3.0%, Mo: 1.4%-2.5%, V: 1.0%-2.0%, Co: 0.30%-1.00%, Ti: 0.01%-0.10%, B: 0.001%-0.010%, N: 0.01%-0.08%, Al: 0.01%-0.10%, with the remainder being Fe and unavoidable impurities.

[0010] A method for preparing 4341E high-speed steel includes the following steps: S1: Weigh the raw materials according to the chemical composition ratio, use an induction furnace as the primary refining equipment, add industrial pure iron and cobalt metal plates into the furnace, heat it with electricity, and add ferrotungsten, ferromolybdenum and carbon raiser in sequence after the furnace charge is in a softened and molten state. After the high melting point alloy is completely melted, add ferrovanadium and continue stirring. Finally, add ferrosilicon for pre-deoxidation to form primary steel liquid. S2: Pour the primary molten steel into a preheated ladle refining furnace, raise the temperature of the molten steel by electric arc heating, and at the same time turn on bottom blowing argon gas stirring. Under strong argon gas stirring, add manganese ferronitride, ferrotitanium ferronitride, ferroboronium ferronitride and high-purity aluminum shot to the molten steel in sequence and keep it for a period of time, and then cast it into a consumable electrode rod for electroslag remelting. S3: After grinding the surface of the consumable electrode rod, place it in an electroslag remelting furnace for remelting. After remelting, seal and shrink the top, and place the steel ingot in a heat insulation cover to slowly cool it to below 200-300℃ before taking it out of the furnace to obtain an electroslag steel ingot. S4: The electroslag steel ingot is heated for homogenization and heat preservation, then multi-directional forging is carried out for billet opening. After forging is completed, it is heated in the furnace for hot rolling. After rolling is completed, it is immediately subjected to slow cooling treatment to obtain hot-deformed steel ingot blank. S5: The billet is subjected to softening annealing, quenching and tempering treatment in sequence to obtain 4341E high-speed steel.

[0011] Preferably, the temperature of the electric heating in step S1 is 1540-1560℃.

[0012] Preferably, the temperature before adding ferrovanadium in step S1 is adjusted to 1510-1530℃.

[0013] Preferably, the industrial pure iron in step S1 has a purity of ≥99.5% and a P and S content of ≤0.01%.

[0014] Preferably, the cobalt plate mentioned in step S1 is of grade Co99.98 with a purity ≥99.9%.

[0015] Preferably, the ferrotungsten in step S1 is of grade FeW80 with a W content of 80%.

[0016] Preferably, the ferromolybdenum in step S1 is grade FeMo60 with a Mo content of 60%.

[0017] Preferably, the carbon raiser in step S1 is low-sulfur graphitized petroleum coke with a fixed carbon content of ≥98.5%.

[0018] Preferably, the ferrovanadium mentioned in step S1 is grade FeV50 with a V content of 50%.

[0019] Preferably, the preheating temperature in step S2 is 600-800℃.

[0020] Preferably, in step S2, the temperature of the molten steel is increased to 1590-1610°C by electric arc heating.

[0021] Preferably, the argon flow rate in step S2 is controlled at 10-20 L / min.

[0022] Preferably, the manganese iron nitride mentioned in step S2 is of grade FeMn65N5, with Mn content ≥65% and N content ≥5%.

[0023] Preferably, the ferrotitanium in step S2 is of grade FeTi30 with a Ti content of 30%.

[0024] Preferably, the ferroboron mentioned in step S2 is grade FeB18 with a B content of 18%.

[0025] Preferably, the high-purity aluminum pellets in step S2 have an Al content ≥ 99.7%.

[0026] Preferably, the remelting in step S3 is carried out using a high-fluorine, low-hydrogen slag system (70% CaF2, 15% Al2O3, 15% CaO).

[0027] Preferably, the slag system described in step S3 is pre-baked at 700-900℃ for 4-6 hours to completely remove the water of crystallization.

[0028] Preferably, the remelting rate in step S3 is 1.5-2.5 kg / min.

[0029] Preferably, the cooling rate in step S3 is 80-120℃ / h.

[0030] Preferably, the homogenization and heat preservation temperature in step S4 is 1150-1180℃, and the heat preservation time is 4-8h.

[0031] Preferably, in step S4, the initial forging temperature of the multi-directional forging billet is controlled at 1150-1180℃, the final forging temperature is controlled at 950-1000℃, and the forging is carried out using a three-upsetting and three-drawing process with a forging ratio of 12-18.

[0032] Preferably, the hot rolling temperature in step S4 is 1020-1080℃.

[0033] Preferably, the softening annealing temperature in step S5 is 840-880℃, and the holding time is 4-6h.

[0034] Preferably, the quenching in step S5 is performed by heating in a salt bath furnace. The first-stage preheating temperature is 500-600℃ and the holding time is 20-40 min. The second-stage preheating temperature is 800-880℃ and the holding time is 20-40 min. Then, the furnace is quickly moved into a high-temperature salt bath at 1180-1200℃ for austenitization.

[0035] Preferably, the tempering temperature in step S5 is 540-570℃, the holding time is 1-2 hours, and the tempering process is repeated 3 times.

[0036] The beneficial effects of this invention are: This invention creatively introduces a nitrogen-titanium-boron ternary microalloying synergistic control mechanism under a specific alloy composition system, and combines it with a full-process precision metallurgical process of induction melting, ladle refining, and electroslag remelting, significantly improving the comprehensive service performance of 4341E high-speed steel. First, the invention significantly improves strength and toughness through in-situ synergistic grain refinement using Ti-N: During the refining stage, a nitrogen source is introduced via nitrogen-containing manganese-iron alloy. Nitrogen induces titanium to form dispersed, high-melting-point Ti(C,N) nanoparticles. These particles have extremely low mismatch with the austenitic matrix, acting as highly efficient heterogeneous nucleation cores, significantly increasing the nucleation rate in the early stages of solidification and fundamentally refining the as-cast grains. Furthermore, the solid solution strengthening effect of nitrogen further enhances the matrix strength, enabling the steel to maintain ultra-high hardness while significantly improving impact toughness, effectively solving the brittle fracture problem caused by coarse grains in traditional high-speed steel.

[0037] Secondly, by strengthening grain boundaries with boron, the risk of intergranular fracture is eliminated: Addressing the defect of high-hardness steel being prone to intergranular brittle fracture, this invention introduces trace amounts of boron. Boron atoms preferentially segregate at austenite grain boundaries, which on the one hand lowers the grain boundary energy and inhibits abnormal grain growth during high-temperature heat treatment; on the other hand, boron can competitively occupy grain boundary vacancies, hindering the diffusion and segregation of harmful impurities such as phosphorus and sulfur to the grain boundaries, thereby significantly purifying and strengthening the grain boundaries and greatly improving the fracture toughness and fatigue resistance of the material.

[0038] Finally, precise metallurgical and hot-working processes ensured the uniformity of the microstructure: by adding microalloying elements during the LF furnace refining process under strong argon protection, the oxidation and burn-off of active elements such as titanium and boron were avoided, ensuring precise control of composition and yield. Combined with a specific electroslag remelting slag system and cooling process, the distribution of microalloyed products became more uniform. Subsequent three-upsetting and three-drawing multi-directional forging and refined heat treatment further broke down the eutectic carbide network and promoted the dispersed precipitation of fine carbides, resulting in a final product with a dense microstructure free of network carbide residues, significantly improving the material's red hardness and cutting life. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0040] The sources or properties of the raw materials used in the embodiments and comparative examples of this invention are as follows: Industrial pure iron: purity ≥99.5%, P and S content ≤0.01%; Cobalt metal plate: grade Co99.98, purity ≥99.9%; Ferrotungsten: grade FeW80, W content 80%; Ferromolybdenum: grade FeMo60, Mo content 60%; Carbon raiser: low-sulfur graphitized petroleum coke, fixed carbon content ≥98.5%; Ferrovanadium: grade FeV50, V content 50%; Ferrosilicon: grade FeSi75, Si content ≥72%; Ferromanganese nitride: grade FeMn65N5, Mn content ≥65%, N content ≥5%; Ferrotitanium: grade FeTi30, Ti content 30%; Ferroboron: grade FeB18, B content 18%; High-purity aluminum shot: Al content ≥99.7%.

[0041] Example 1: A method for preparing 4341E high-speed steel, the specific steps of which are as follows: (1) According to the chemical composition (mass percentage), C: 0.90%; Si: 0.80%; Mn: 0.20%; W: 1.8%; Mo: 1.4%; V: 1.0%; Co: 0.30%; Ti: 0.01%; B: 0.001%; ​​N: 0.01%; Al: 0.01%; the remainder is Fe and unavoidable impurities. Weigh out industrial pure iron, cobalt metal plate, ferrotungsten, ferromolybdenum, carbon raiser, ferrovanadium, ferrosilicon, ferromanganese nitride, ferrotitanium, ferroboron, and high-purity aluminum shot as raw materials. Before use, all raw materials are placed in an oven and baked at 150°C for 2 hours to remove surface moisture. (2) Using an induction furnace as the primary refining equipment, firstly, industrial pure iron and cobalt metal plates are added into the induction furnace and heated to 1540°C. After the furnace charge softens and melts, ferrotungsten, ferromolybdenum and carbon raiser are added in sequence. The furnace is kept warm and stirred for 10 minutes. After the high melting point alloy is completely melted, the temperature is adjusted to 1510°C. Ferrovanadium is added and stirred for another 5 minutes. After the composition is uniform, ferrosilicon is added and stirred for 3 minutes for pre-deoxidation to form primary steel liquid. (3) Pour the primary steel liquid into the ladle refining furnace preheated to 600°C, raise the temperature of the steel liquid by electric arc heating and stabilize it at 1590°C, and at the same time turn on the bottom blowing argon gas. The argon gas flow rate is controlled at 10L / min. Under strong argon gas stirring, nitrogen-containing manganese iron, titanium iron, boron iron and metallic aluminum are added to the steel liquid. Keep it under argon gas stirring for 15min, let it stand for 5min, and then cast it into a consumable electrode rod for electroslag remelting. (4) After the surface of the consumable electrode rod is polished, it is installed on the electroslag remelting furnace. A high-fluorine and low-hydrogen slag system (70% CaF2, 15% Al2O3, 15% CaO) is selected. The slag material has been pre-baked at 700℃ for 4 hours to completely remove the crystal water. Then it is remelted in a forced water-cooled crystallizer. The melting rate is controlled at 1.5 kg / min. After the remelting is completed, the steel ingot is capped and fed. Then the steel ingot is placed in the heat preservation cover and slowly cooled to below 200℃ at a rate of 80℃ / h before being taken out of the furnace to obtain a dense electroslag steel ingot. (5) The electroslag steel ingot is heated to 1150℃ for homogenization and heat preservation for 4 hours. Then, it is forged using forging equipment for multi-directional forging. The initial forging temperature is controlled at 1150℃ and the final forging temperature is controlled at 950℃. The forging is carried out using a three-upsetting and three-drawing process with a forging ratio of 12. After forging, it is heated to 1020℃ in the furnace for hot rolling. After rolling into finished products, it is immediately buried in dry quartz sand and slowly cooled to room temperature to obtain hot-deformed steel ingot blanks. (6) The hot-deformed steel ingot blanks were subjected to softening annealing treatment at a temperature of 840℃ and a holding time of 4h. Then, they were slowly cooled to 500℃ in the furnace at a rate of 15℃ / h. After being removed from the furnace, they were air-cooled and then quenched in a salt bath furnace. The first preheating temperature was 500℃ and the holding time was 20min. The second preheating temperature was 800℃ and the holding time was 20min. Then, they were quickly moved into a high-temperature salt bath at 1180℃ for austenitization. After being removed, they were oil-cooled to room temperature. Finally, the quenched sample was cleaned and placed in a pit tempering furnace at 540℃. After holding for 1h, it was removed from the furnace and air-cooled. This tempering operation was repeated 3 times to obtain 4341E high-speed steel.

[0042] Example 2: A method for preparing 4341E high-speed steel, the specific steps of which are as follows: (1) According to the chemical composition (mass percentage), C: 0.95%; Si: 0.10%; Mn: 0.30%; W: 2.6%; Mo: 2.0%; V: 1.5%; Co: 0.70%; Ti: 0.07%; B: 0.050%; N: 0.04%; Al: 0.05%; the remainder is Fe and unavoidable impurities. Weigh out industrial pure iron, cobalt metal plate, ferrotungsten, ferromolybdenum, carbon raiser, ferrovanadium, ferrosilicon, ferromanganese nitride, ferrotitanium, ferroboron, and high-purity aluminum shot as raw materials. Before use, all raw materials are placed in an oven and baked at 180°C for 3 hours to remove surface moisture. (2) Using an induction furnace as the primary refining equipment, firstly, industrial pure iron and cobalt metal plates are added into the induction furnace and heated to 1550°C. After the furnace charge softens and melts, ferrotungsten, ferromolybdenum and carbon raiser are added in sequence. The furnace is kept warm and stirred for 13 minutes. After the high melting point alloy is completely melted, the temperature is adjusted to 1520°C. Ferrovanadium is added and stirring is continued for 8 minutes. After the composition is uniform, ferrosilicon is added and stirred for 4 minutes for pre-deoxidation to form primary steel liquid. (3) Pour the primary steel liquid into the ladle refining furnace preheated to 700°C, raise the temperature of the steel liquid by electric arc heating and stabilize it at 1600°C, and at the same time turn on the bottom blowing argon gas. The argon gas flow rate is controlled at 15L / min. Under strong argon gas stirring, nitrogen-containing manganese iron, titanium iron, boron iron and metallic aluminum are added to the steel liquid. Keep it under argon gas stirring for 18 minutes, let it stand for 8 minutes, and then cast it into a consumable electrode rod for electroslag remelting. (4) After the surface of the consumable electrode rod is polished, it is installed on the electroslag remelting furnace. A high-fluorine and low-hydrogen slag system (70% CaF2, 15% Al2O3, 15% CaO) is selected. The slag material has been pre-baked at 800℃ for 5h to completely remove the crystal water. Then it is remelted in a forced water-cooled crystallizer. The melting rate is controlled at 2kg / min. After the remelting is completed, the steel ingot is capped and fed. Then the steel ingot is placed in the heat preservation cover and slowly cooled to below 250℃ at a rate of 100℃ / h before being taken out of the furnace to obtain a dense electroslag steel ingot. (5) The electroslag steel ingot is heated to 1170℃ for homogenization and heat preservation for 6 hours. Then, it is forged using forging equipment for multi-directional forging. The initial forging temperature is controlled at 1160℃ and the final forging temperature is controlled at 980℃. The forging is carried out using a three-upsetting and three-drawing process with a forging ratio of 15. After forging, it is heated to 1050℃ in the furnace for hot rolling. After rolling into finished products, it is immediately buried in dry quartz sand and slowly cooled to room temperature to obtain a hot-deformed steel ingot blank. (6) The hot-deformed steel ingot blanks were subjected to softening annealing treatment at a temperature of 850℃ and a holding time of 5h. Then, they were slowly cooled to 500℃ in the furnace at a rate of 25℃ / h. After being removed from the furnace, they were air-cooled. Then, they were quenched by heating in a salt bath furnace. The first preheating temperature was 550℃ and the holding time was 30min. The second preheating temperature was 850℃ and the holding time was 30min. Then, they were quickly moved into a high-temperature salt bath at 1190℃ for austenitization. After being removed, they were oil-cooled to room temperature. Finally, the quenched sample was cleaned and placed in a pit tempering furnace at 560℃. After holding for 2h, it was removed from the furnace and air-cooled. This tempering operation was repeated 3 times to obtain 4341E high-speed steel.

[0043] Example 3: A method for preparing 4341E high-speed steel, the specific steps of which are as follows: (1) According to the chemical composition (mass percentage), C: 1.00%; Si: 1.20%; Mn: 0.50%; W: 3.0%; Mo: 2.5%; V: 2.0%; Co: 1.00%; Ti: 0.10%; B: 0.010%; N: 0.08%; Al: 0.10%; the remainder is Fe and unavoidable impurities. Weigh out industrial pure iron, cobalt metal plate, ferrotungsten, ferromolybdenum, carbon raiser, ferrovanadium, ferrosilicon, ferromanganese nitride, ferrotitanium, ferroboron, and high-purity aluminum shot as raw materials. Before use, all raw materials are placed in an oven and baked at 200°C for 4 hours to remove surface moisture. (2) Using an induction furnace as the primary refining equipment, firstly, industrial pure iron and cobalt metal plates are added into the induction furnace and heated to 1560°C. After the furnace charge softens and melts, ferrotungsten, ferromolybdenum and carbon raiser are added in sequence. The furnace is kept warm and stirred for 15 minutes. After the high melting point alloy is completely melted, the temperature is adjusted to 1530°C. Ferrovanadium is added and stirring is continued for 10 minutes. After the composition is uniform, ferrosilicon is added and stirred for 5 minutes for pre-deoxidation to form primary steel liquid. (3) Pour the primary steel liquid into the ladle refining furnace preheated to 800°C, raise the temperature of the steel liquid by electric arc heating and stabilize it at 1610°C, and at the same time turn on the bottom blowing argon gas, with the argon gas flow rate controlled at 20L / min. Under strong argon gas stirring, nitrogen-containing manganese iron, titanium iron, boron iron and metallic aluminum are added to the steel liquid. Keep it under argon gas stirring for 20min, let it stand for 10min, and then cast it into a consumable electrode rod for electroslag remelting. (4) After the surface of the consumable electrode rod is polished, it is installed on the electroslag remelting furnace. A high-fluorine and low-hydrogen slag system (70% CaF2, 15% Al2O3, 15% CaO) is selected. The slag material has been pre-baked at 900℃ for 6 hours to completely remove the crystal water. Then it is remelted in a forced water-cooled crystallizer. The melting rate is controlled at 2.5 kg / min. After the remelting is completed, the steel ingot is capped and fed. Then the steel ingot is placed in the heat preservation cover and slowly cooled to below 300℃ at a rate of 120℃ / h before being taken out of the furnace to obtain a dense electroslag steel ingot. (5) The electroslag steel ingot is heated to 180°C for homogenization and heat preservation for 8 hours. Then, it is forged using forging equipment for multi-directional forging. The initial forging temperature is controlled at 1180°C and the final forging temperature is controlled at 1000°C. The forging is carried out using a three-upsetting and three-drawing process with a forging ratio of 18. After forging, it is heated to 1080°C in the furnace for hot rolling. After rolling into finished products, it is immediately buried in dry quartz sand and slowly cooled to room temperature to obtain a hot-deformed steel ingot blank. (6) The hot-deformed steel ingot blanks were subjected to softening annealing treatment at a temperature of 880℃ and a holding time of 6h. Then, they were slowly cooled to 500℃ in the furnace at a rate of 30℃ / h. After being removed from the furnace, they were air-cooled. Then, they were quenched by heating in a salt bath furnace. The first preheating temperature was 600℃ and the holding time was 40min. The second preheating temperature was 880℃ and the holding time was 40min. Then, they were quickly moved into a high-temperature salt bath at 1200℃ for austenitization. After being removed, they were oil-cooled to room temperature. Finally, the quenched sample was cleaned and placed in a pit tempering furnace at 570℃. After holding for 2h, it was removed from the furnace and air-cooled. This tempering operation was repeated 3 times to obtain 4341E high-speed steel.

[0044] Comparative Example 1: The difference from Example 2 is that ferrotitanium and ferroboron are not added in step (3), while the remaining steps and process parameters are completely consistent with Example 2.

[0045] Comparative Example 2: The difference from Example 2 is that nitrogen-containing manganese iron, titanium iron and boron iron are not added in step (3), while the remaining steps and process parameters are completely consistent with Example 2.

[0046] Comparative Example 3: The difference from Example 2 is that in step (3), nitrogen-containing ferromanganese is replaced with ordinary high-carbon ferromanganese (grade FeMn65, Mn content 65%). The remaining steps and process parameters are completely consistent with Example 2.

[0047] Comparative Example 4: The difference from Example 2 is that ferroboron is not added in step (3), while the remaining steps and process parameters are completely consistent with Example 2.

[0048] Performance testing Rockwell hardness: The test was conducted according to GB / T 230.1-2018 "Metallic materials Rockwell hardness test - Part 1: Test method". The samples obtained from the examples and comparative examples were used. The sample size was 20mm×20mm×10mm. The upper and lower surfaces of the sample were ground and polished to ensure that the surface roughness Ra≤0.8μm. An HR-150A Rockwell hardness tester was used with a C scale (HRC) and a diamond cone indenter. The total test force was 1471N (150kgf) and the holding time was 4s. Five test points were evenly selected on the sample surface with a point spacing of more than 3mm. The highest and lowest values ​​were removed, and the average value of the remaining three points was taken as the final hardness result. Impact toughness: The test was conducted according to GB / T 229-2020 "Charpy Impact Test Method for Metallic Materials". The samples obtained from the examples and comparative examples were processed into standard unnotched impact specimens with a size of 10mm×10mm×55mm and a surface roughness Ra≤1.6μm. The room temperature impact test was conducted using a JBW-300B microcomputer-controlled pendulum impact testing machine with an initial pendulum energy of 300J and an impact velocity of 5.2m / s. Three parallel specimens were taken for each test group, and the average value of their impact absorbed energy (AKU) was calculated. Grain size: The comparative method in GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals" was used. Samples were taken from the cross-section of the samples obtained in the examples and comparative examples. After grinding and polishing, the samples were etched with 4% nitric acid alcohol solution until the grain boundaries were clearly visible. The morphology of austenite grains was observed under a metallographic microscope at 100x magnification. The most representative field of view was selected and compared with the standard rating chart to determine the grain size grade. Red hardness: The samples obtained in the examples and comparative examples were placed in a high-temperature box-type resistance furnace and kept at 600°C for 4 hours. After being taken out and air-cooled to room temperature, their Rockwell hardness values ​​were tested again according to GB / T 230.1-2018 standard. The test results are shown in Table 1.

[0049] Table 1 Performance Test Results Rockwell hardness (HRC) impact toughness (J) grain size red hardness (HRC) Example 1 64.4 29.5 11.0 60.5 Example 2 65.3 34.2 12.0 61.4 Example 3 66.1 25.8 11.5 62.5 Comparative Example 1 62.8 18.5 8.5 58.2 Comparative Example 2 62.1 15.2 8.0 57.4 Comparative Example 3 63.6 21.4 9.5 59.1 Comparative Example 4 65.0 24.6 11.0 60.9 As can be seen from the data in Examples 1-3 of Table 1, the 4341E high-speed steel prepared by this invention exhibits excellent and balanced comprehensive mechanical properties under different alloy composition ratios. In practical applications, this material can not only resist high-temperature wear generated by high-speed cutting, but also effectively avoid chipping failure caused by sudden changes in cutting force. This data strongly proves that this invention has successfully solved the industry problem of the difficulty in achieving both hardness and toughness in traditional high-speed steel by precisely controlling trace elements and metallurgical processes, and has obtained a tooling material with dense structure and reliable performance.

[0050] As can be seen from the data in Example 2 and Comparative Example 1 in Table 1, the synergistic addition of titanium and boron plays a decisive role in improving the brittleness of the material. It is speculated that the introduction of titanium and boron likely leads to the formation of a large number of dispersed nucleation particles in the early stages of solidification, significantly increasing the nucleation rate. Simultaneously, the grain boundary segregation effect of boron may inhibit excessive grain growth at high temperatures. This microstructure optimization resulting from microalloying leads to higher red hardness and excellent impact resistance in the material, confirming that titanium and boron are indispensable key components in the system of this invention.

[0051] The data from Example 2 and Comparative Example 2 in Table 1 demonstrate the necessity of the microalloying strategy for improving the performance of 4341E high-speed steel. This is presumably due to the successful alteration of the material's crystallization kinetics by precisely introducing trace elements such as nitrogen, titanium, and boron during the refining stage. The dispersed phases formed by these trace elements not only refine the as-cast microstructure as crystal nuclei but also hinder grain coarsening during subsequent heat treatment by pinning grain boundaries. This endows the material with comprehensive service performance far exceeding that of conventional smelting methods, achieving high-performance output from low-cost raw materials.

[0052] As can be seen from the data in Example 2 and Comparative Example 3 in Table 1, nitrogen plays a key role in inducing nucleation in the microalloying system of this invention. It is speculated that the grain refinement and toughening effect of microalloying can be maximized only under the condition of coexistence of nitrogen and titanium.

[0053] As can be seen from the data in Example 2 and Comparative Example 4 in Table 1, boron atoms may segregate at the austenite grain boundaries, reducing the grain boundary energy, or suppressing the harmful segregation of impurity elements such as phosphorus and sulfur at the grain boundaries, thereby significantly improving the bonding strength and plasticity of the grain boundaries. Therefore, although boron does not significantly change the hardness, it is a safety net for improving the toughness margin of the material. Its combined use with titanium and nitrogen achieves the dual protection of fine grains and solid grains.

[0054] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A type of 4341E high-speed steel, characterized in that, The chemical composition of the 4341E high-speed steel, by mass percentage, includes C: 0.90%-1.00%, Si: 0.80%-1.20%, Mn: 0.20%-0.50%, W: 1.8%-3.0%, Mo: 1.4%-2.5%, V: 1.0%-2.0%, Co: 0.30%-1.00%, Ti: 0.01%-0.10%, B: 0.001%-0.010%, N: 0.01%-0.08%, Al: 0.01%-0.10%, with the remainder being Fe and unavoidable impurities.

2. A method for preparing 4341E high-speed steel according to claim 1, characterized in that, Includes the following steps: S1: Weigh the raw materials according to the chemical composition ratio and smelt them. After heating the industrial pure iron and cobalt metal plate to a molten state by electric current, add ferrotungsten, ferromolybdenum and carbon raiser in sequence. After melting, add ferrovanadium and ferrosilicon to form primary molten steel. S2: Pour the primary molten steel into the refining furnace, raise the temperature of the molten steel by electric arc heating, and at the same time turn on bottom blowing argon gas to stir. Add manganese ferronitride, ferrotitanium ferronitride and high-purity aluminum shot to the molten steel in sequence, and form a consumable electrode rod by casting. S3: The consumable electrode rod is placed in an electroslag remelting furnace for remelting to form an electroslag steel ingot; S4: The electroslag steel ingot is homogenized and kept at a constant temperature, and then forged and hot rolled to obtain a hot-deformed steel ingot blank. S5: The hot-deformed steel ingot blank is subjected to softening annealing, quenching and tempering treatment in sequence to obtain 4341E high-speed steel.

3. The preparation method according to claim 2, characterized in that, The temperature for electric heating in step S1 is 1540-1560℃; the temperature before adding ferrovanadium is adjusted to 1510-1530℃.

4. The preparation method according to claim 2, characterized in that, In step S1, the cobalt plate is of grade Co99.98 with a purity ≥99.9%; the ferrotungsten is of grade FeW80 with a W content of 80%; the ferromolybdenum is of grade FeMo60 with a Mo content of 60%; the carbon raiser is low-sulfur graphitized petroleum coke with a fixed carbon content ≥98.5%; and the ferrovanadium is of grade FeV50 with a V content of 50%.

5. The preparation method according to claim 2, characterized in that, In step S2, the temperature of the molten steel is raised to 1590-1610℃ by electric arc heating; the argon flow rate is controlled at 10-20L / min.

6. The preparation method according to claim 2, characterized in that, In step S2, the manganese ferronitride is grade FeMn65N5, with Mn content ≥65% and N content ≥5%; the ferrotitanium is grade FeTi30, with Ti content 30%; the ferroboron is grade FeB18, with B content 18%; and the high-purity aluminum shot has an Al content ≥99.7%.

7. The preparation method according to claim 2, characterized in that, The remelting rate in step S3 is 1.5-2.5 kg / min.

8. The preparation method according to claim 2, characterized in that, In step S4, the homogenization holding temperature is 1150-1180℃, and the holding time is 4-8h; the initial forging temperature is controlled at 1150-1180℃, the final forging temperature is controlled at 950-1000℃, and the forging is carried out using a three-upsetting and three-drawing process with a forging ratio of 12-18; the hot rolling temperature is 1020-1080℃.

9. The preparation method according to claim 2, characterized in that, The softening annealing temperature in step S5 is 840-880℃, and the holding time is 4-6h; the quenching is carried out in a salt bath furnace, with the first preheating temperature at 500-600℃ and the holding time at 20-40min, the second preheating temperature at 800-880℃ and the holding time at 20-40min, and then it is quickly transferred to a high-temperature salt bath at 1180-1200℃ for austenitization; the tempering treatment temperature is 540-570℃, the holding time is 1-2h, and the tempering treatment is performed 3 times.