Preparation method of vanadium and rhenium composite ferromolybdenum intermediate alloy and application thereof

Abstract

The application provides a preparation method of vanadium and rhenium composite molybdenum-iron intermediate alloy and application thereof. The application carries out synergistic extraction on a solution after molybdenum extraction from molybdenum concentrate sulfur-phosphorus mixed acid, synchronously recovers molybdenum and rhenium and selectively extracts vanadium, and obtains composite molybdenum oxide containing MoO3, Re2O7 and V2O5 through back extraction and roasting; the composite molybdenum-iron intermediate alloy containing vanadium and rhenium is prepared through an off-furnace silicon-aluminum thermal reduction one-step method; finally, the composite molybdenum-iron is added into alloy steel, and the molybdenum and rhenium are used for regulating and controlling the spheroidization and refinement of vanadium carbide precipitation morphology and the stabilization of high-hardness 11 type vanadium carbide, so that the strength and toughness and wear resistance life of the alloy steel are significantly improved. The application realizes the resource utilization of the rare and scattered metal rhenium, greatly improves the performance of the alloy steel and does not significantly increase the cost.

Description

Technical Field

[0001] This invention belongs to the field of wear-resistant metal materials and comprehensive resource utilization technology, and relates to a method for preparing a vanadium- and rhenium-containing composite ferromolybdenum intermediate alloy and its application, particularly a method for preparing a vanadium- and rhenium-containing composite ferromolybdenum reinforced alloy steel. Background Technology

[0002] Alloy steels (such as chromium-molybdenum steel and medium-chromium alloy steel series) are irreplaceable core wear-resistant materials in fields such as mining crushing, railway turnouts, and engineering machinery due to their excellent work hardening ability and high toughness. However, as mining equipment develops towards larger size and higher efficiency, the service conditions of key wear-resistant components such as liners, hammers, and toothed plates are becoming increasingly harsh. The shortcomings of traditional alloy steels, such as insufficient work hardening under low impact stress, low yield strength, and high initial wear rate, are becoming increasingly prominent, resulting in high equipment maintenance costs and seriously restricting the improvement of mining production efficiency.

[0003] Studies have shown that introducing dispersed micro- and nano-sized hard carbide particles into the alloy steel matrix is ​​one of the most effective ways to strengthen it and significantly improve its wear resistance. Among the many types of carbides, vanadium carbide (VC) is considered an ideal strengthening phase due to its extremely high hardness (approximately 2800-3000 HV) and thermodynamic stability. However, the precipitation morphology and grain size of vanadium carbide in the austenitic matrix have a decisive influence on its strengthening effect: coarse, sharp, or network-like vanadium carbide can cleave the matrix and become crack initiation sites; while fine, spherical, and dispersed vanadium carbide can effectively pin dislocations, significantly improving wear resistance while maintaining good toughness.

[0004] Currently, a consensus has been reached in the field of materials science: the precipitation behavior of vanadium carbide can be precisely controlled by the combined addition of molybdenum (Mo) and rhenium (Re). Molybdenum (Mo) can reduce the diffusion rate of vanadium in austenite and inhibit the preferential growth of vanadium carbide at grain boundaries; while rhenium (Re), as a highly surface-active element, can adsorb on specific crystal faces of vanadium carbide, changing its growth kinetics and promoting the growth of vanadium carbide towards spheroidization and refinement. Vanadium carbides exist in various crystal structures (such as V4C3, V8C7, etc.), among which type 11 vanadium carbide with a specific crystal orientation (usually referring to the cubic structure VC1-x) has the highest hardness, the best coherence with the matrix, and the most significant strengthening effect. The combined addition of molybdenum and rhenium can stabilize the thermodynamic conditions for the formation of this high-hardness vanadium carbide, inhibit the precipitation of other inefficient carbides, and thus maximize the precipitation strengthening effect.

[0005] Although the theoretical mechanism of molybdenum-rhenium-vanadium composite alloying is well-established, the high cost of raw materials remains a significant obstacle to its industrial application. The traditional method for achieving this technological path involves adding ferrovanadium, ferromolybdenum, and ferrhenium to molten steel separately. Ferrovanadium and ferromolybdenum, as commonly used alloying agents, are already expensive. Ferrrhenium, due to the extreme rarity and high price of metallic rhenium, is almost exclusively used in high-temperature alloys and aerospace materials. In the field of ordinary wear-resistant steel, enterprises simply cannot afford its usage cost, thus creating a prominent contradiction between ideal performance and impractical cost. The mining industry urgently needs a disruptive technological solution that can leverage the synergistic strengthening effect of Mo-Re-V to improve the service life of alloy steel without causing a dramatic increase in cost.

[0006] Therefore, how to develop a more suitable technical solution to solve the above-mentioned technical problems of existing molybdenum-rhenium-vanadium composite alloy steel has become one of the focuses of attention for many researchers in the industry. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is a method for preparing a vanadium-rhenium composite ferromolybdenum master alloy and its application, particularly a method for preparing a vanadium-rhenium composite ferromolybdenum reinforced alloy steel. The present invention innovatively proposes a technical route that involves the synergistic extraction of molybdenum, rhenium, and vanadium from a molybdenum concentrate metallurgical solution followed by one-step aluminothermic reduction to prepare a low-cost vanadium-rhenium composite ferromolybdenum, which is then applied to strengthen alloy steel, thereby fully leveraging the morphology and phase structure regulation effects of vanadium carbide. This invention overcomes the limitations of traditional high-cost single ferroalloy additions, achieving an organic unity between comprehensive resource utilization and the preparation of high-performance wear-resistant materials. Moreover, the method is simple, the conditions are mild, the stability is good, and the operability is strong, making it more suitable for industrial production and application.

[0008] This invention provides a method for preparing a vanadium- and rhenium-containing composite ferromolybdenum master alloy, comprising the following steps: 1) Molybdenum concentrate is leached in a sulfur-phosphorus mixed acid system to obtain a molybdenum-extracted liquid, which is then extracted to obtain an organic phase loaded with molybdenum, rhenium, and vanadium. 2) After back-extraction of the organic phase loaded with molybdenum, rhenium, and vanadium obtained in the above steps with ammonia water, a mixed solution containing molybdenum, rhenium, vanadium, and ammonium is obtained; 3) The mixed solution containing molybdenum, rhenium, vanadium and ammonium obtained in the above steps is crystallized and calcined to obtain a composite oxide containing molybdenum oxide, rhenium oxide and vanadium oxide; 4) Using the composite oxide, ferrosilicon, aluminum powder and other ingredients obtained in the above steps as raw materials, the composite ferromolybdenum alloy melt containing vanadium and rhenium is obtained by smelting using the furnace-external aluminothermic reduction method. After further processing, the composite ferromolybdenum alloy intermediate containing vanadium and rhenium is obtained.

[0009] Preferably, the molybdenum concentrate, based on the elemental mass content, comprises Mo: 50%~60%, S: 30%~40%, Re: 15~40 g / t, and V: 50~150 g / t; In the sulfuric acid-phosphoric acid mixed system, the concentration of sulfuric acid is 0.5~2 mol / L and the concentration of phosphoric acid is 1~2.5 mol / L; The leaching time is 1-4 hours; The leaching temperature is 70~120℃; The liquid-to-solid ratio of the leaching is 5~15L / kg.

[0010] Preferably, the concentration of iron in the molybdenum extraction solution is 100-130 mg / L; The concentration of vanadium in the molybdenum extraction solution is 150-180 g / L. The concentration of copper in the molybdenum extraction solution is 6000~7500 mg / L; The concentration of rhenium in the molybdenum extraction solution is 40-60 mg / L; The concentration of residual molybdenum in the molybdenum extraction solution is 1000~3000 mg / L.

[0011] Preferably, the extractant used in the extraction process includes an amine extractant; The volume concentration of the extractant is 5% to 40%; In the extraction process, the volume ratio of the organic phase to the aqueous phase is (5~1):(1~2); The extraction process is performed at a temperature of 15~50℃; The extraction process takes 5 to 30 minutes.

[0012] Preferably, the mass concentration of the ammonia water is 5% to 15%; In the back-extraction, the volume ratio of the oil phase to the water phase is (5~1):(1~2). The temperature for the back-extraction is 20~60℃; The back-extraction time is 5-30 min; The vanadium and rhenium-containing composite ferromolybdenum master alloy is a master alloy used for alloy steel.

[0013] Preferably, the calcination temperature is 450~600℃; The roasting time is 2-4 hours; In the composite oxide, the mass content of molybdenum oxide is 60%~80%; In the composite oxide, the rhenium oxide content is 0.05%~0.5% by mass; The vanadium oxide content in the composite oxide is 1% to 5% by mass.

[0014] Preferably, the ingredients include one or more of steel scrap, iron scale, saltpeter, and slag-forming agent; The raw materials, by mass parts, include: 100 parts by weight of composite molybdenum oxide; 15-25 parts by weight of ferrosilicon; 25-40 parts by weight of aluminum powder; 10-20 parts by weight of steel scrap; Iron scale, 5-15 parts by weight; Saltpeter, 5-12 parts by weight; Slag-forming agent: 10-18 parts by weight.

[0015] Preferably, the external silicon-aluminate thermal reduction method adopts a bottom ignition method; The smelting time is 3-8 minutes; The smelting temperature is 1850~2100℃; After smelting, the melt is allowed to stand and separate into layers for 10-20 minutes. The post-processing includes crushing and screening steps; In the vanadium and rhenium-containing composite ferromolybdenum, the mass content of Mo is 55%~65%, the mass content of V is 1.0%~4.5%, the mass content of Re is 0.05%~0.4%, and Fe and unavoidable impurities are present.

[0016] The present invention also provides the application of the vanadium and rhenium-containing composite ferromolybdenum master alloy prepared by any of the above technical solutions in the preparation of alloy steel to increase the proportion of spheroidized vanadium carbide and / or type 11 vanadium carbide in alloy steel.

[0017] Preferably, the vanadium- and rhenium-containing composite ferromolybdenum is used in the alloy steel melt at a mass ratio of 0.5% to 3.0%. In the alloy steel, the vanadium content is 0.05%~0.25% by mass; In the alloy steel, the molybdenum content is 0.3% to 1.5% by mass; In the alloy steel, the rhenium content is 0.001%~0.01% by mass; In the alloy steel, the average particle size of vanadium carbide particles is less than or equal to 2 μm; In the alloy steel, vanadium carbide particles are distributed in a spherical morphology; In the alloy steel, the volume fraction of type 11 vanadium carbide accounts for more than 60% of the total vanadium carbide.

[0018] This invention provides a method for preparing a vanadium-rhenium composite ferromolybdenum master alloy, comprising the following steps: First, molybdenum concentrate is leached in a sulfur-phosphorus mixed acid system to obtain a molybdenum-extracted liquid, which is then extracted to obtain an organic phase loaded with molybdenum, rhenium, and vanadium. Next, the organic phase is back-extracted with ammonia to obtain a mixed solution containing molybdenum, rhenium, vanadium, and ammonium. Then, the mixed solution containing molybdenum, rhenium, vanadium, and ammonium is crystallized and calcined to obtain a composite oxide containing molybdenum oxide, rhenium oxide, and vanadium oxide. Finally, the composite oxide, ferrosilicon, aluminum powder, and other ingredients are used as raw materials and smelted using an external aluminothermic reduction method to obtain a vanadium-rhenium composite ferromolybdenum alloy melt. After post-treatment, a vanadium-rhenium composite ferromolybdenum master alloy is obtained. Compared with existing technologies, this invention argues that in the current hydrometallurgical process of molybdenum concentrate, the associated valuable metals rhenium and vanadium are usually separated, discarded, or inefficiently recovered as impurities or low-value byproducts. Traditional processes for separating and purifying molybdenum, rhenium, and vanadium are complex and lengthy, resulting in extremely high costs for obtaining pure single-metal compounds (such as ammonium molybdate and ammonium rheniumate). However, by shifting the focus away from complete separation and purification and instead utilizing their natural symbiotic relationship to produce Mo-Re-V composite oxides in a single step, and then preparing vanadium-rhenium composite ferromolybdenum master alloys at low cost, the expensive single-rhenium ferromolybdenum preparation process can be fundamentally bypassed. This allows for the resource utilization of waste materials and provides an affordable composite alloy raw material for the composite strengthening of alloy steel. Thus, it achieves both comprehensive utilization and efficient recovery of molybdenum, rhenium, and vanadium resources, and simultaneously incorporates the three elements into alloy steel in the form of composite ferromolybdenum, fully leveraging their synergistic strengthening effect.

[0019] Based on this, this invention creatively designs a method for preparing a vanadium-rhenium composite ferromolybdenum master alloy and its application, which is a method for preparing vanadium-rhenium composite ferromolybdenum reinforced alloy steel. This invention proposes a technical route that involves the synergistic extraction of molybdenum, rhenium, and vanadium from a molybdenum concentrate metallurgical solution followed by one-step aluminothermic reduction to prepare a low-cost vanadium-rhenium composite ferromolybdenum, which is then applied to strengthen alloy steel, fully leveraging the morphology and phase structure regulation effects of vanadium carbide. This route overcomes the limitations of traditional high-cost single ferroalloy additions, achieving comprehensive utilization and efficient recovery of molybdenum, rhenium, and vanadium resources. It also allows the simultaneous addition of the three elements in the form of composite ferromolybdenum to alloy steel, fully utilizing their synergistic strengthening effect, thus achieving an organic unity between comprehensive resource utilization and the preparation of high-performance wear-resistant materials.

[0020] This invention presents a novel, resource-efficient process for preparing vanadium-rhenium composite ferromolybdenum using a short-process "synergistic extraction-co-reduction" method. This invention abandons the complex separation routes of existing technologies that pursue high-purity single metal salts. Instead, it innovatively utilizes an extractant with synergistic effects on molybdenum and rhenium to simultaneously recover molybdenum and rhenium in a single extraction step, while selectively co-extracting vanadium. Subsequently, a naturally proportioned composite oxide containing MoO3, R2O7, and V2O5 is obtained through direct calcination, followed by a one-step aluminothermic reduction process to produce a vanadium-rhenium composite ferromolybdenum alloy. This process not only eliminates the high cost of complete separation of molybdenum, rhenium, and vanadium but also transforms the rhenium and vanadium resources lost in traditional processes into valuable resources. It provides an unprecedented low-cost molybdenum-rhenium-vanadium composite additive carrier for downstream alloy steels, solving the industry problem of high costs associated with using rhenium-ferromolybdenum alone. Meanwhile, this invention, for the first time, achieves synergistic regulation of vanadium carbide in alloy steel through low-cost composite ferromolybdenum. It utilizes molybdenum, rhenium, and vanadium from the self-made composite ferromolybdenum to replace the expensive single ferromolybdenum, ferrovanadium, and rhenium ferromanganese used in traditional processes. When this composite ferromolybdenum is added to the alloy steel melt, vanadium acts as a carbide formation source, resulting in the precipitation of a large number of dispersed vanadium carbide particles. The synergistic effect of molybdenum and rhenium during precipitation promotes significant spheroidization and refinement of the vanadium carbide particles, preventing sharp-edged carbides from cutting the matrix. More importantly, the composite effect of molybdenum and rhenium promotes the preferential and abundant formation of high-hardness, high-stability type 11 vanadium carbide, suppressing the occurrence of other inefficient carbides.

[0021] This invention resolves the fundamental contradiction between improving the performance and controlling the cost of alloy steel in mining through a resource recycling approach. It does not increase the additional cost of rhenium metal procurement, but instead extracts valuable elements from metallurgical wastewater from molybdenum concentrate. This makes the cost of the prepared vanadium-rhenium composite ferromolybdenum significantly lower than that of a mixture of ferrovanadium, ferromolybdenum, and ferrhenium. When applied to mining alloy steels (such as large crusher liners, mill liners, and gyratory liners), it significantly improves the wear life and impact resistance of the alloy steel by maximizing the fine-grain strengthening and carbide spheroidization strengthening effects, while maintaining or even slightly reducing material costs. This invention provides a disruptive technological solution that combines economy and high performance for fields such as mining and building materials that are extremely cost-sensitive yet seek the ultimate wear life. Attached Figure Description

[0022] Figure 1 The image shows the microstructure of the 42CrMo steel prepared in Example 1 of this invention. Figure 2 The image shows the microstructure of the medium-chromium alloy steel prepared in Example 2 of this invention. Figure 3 This is a comparison diagram of the impact toughness of alloy steels prepared in the embodiments and comparative examples of the present invention. Detailed Implementation

[0023] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the technical solutions of the present invention.

[0024] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0025] The purity of the raw materials used in this invention is not particularly limited. Preferably, the purity is industrial pure, or conventional in the fields of molybdenum concentrate processing or alloy steel preparation.

[0026] All raw materials of this invention are conventional in the field, and each brand name and abbreviation is clear and distinct in its relevant application. Those skilled in the art can purchase them from the market or prepare them by conventional methods based on the brand name, abbreviation and corresponding application.

[0027] In all processes of this invention, the abbreviations are conventional abbreviations in the field. Each abbreviation is clear and unambiguous in its relevant application area, and those skilled in the art can understand its conventional process steps based on the abbreviation.

[0028] This invention provides a method for preparing a vanadium- and rhenium-containing composite ferromolybdenum master alloy, comprising the following steps: 1) Molybdenum concentrate is leached in a sulfur-phosphorus mixed acid system to obtain a molybdenum-extracted liquid, which is then extracted to obtain an organic phase loaded with molybdenum, rhenium, and vanadium. 2) After back-extraction of the organic phase loaded with molybdenum, rhenium, and vanadium obtained in the above steps with ammonia water, a mixed solution containing molybdenum, rhenium, vanadium, and ammonium is obtained; 3) The mixed solution containing molybdenum, rhenium, vanadium and ammonium obtained in the above steps is crystallized and calcined to obtain a composite oxide containing molybdenum oxide, rhenium oxide and vanadium oxide; 4) Using the composite oxide, ferrosilicon, aluminum powder and other ingredients obtained in the above steps as raw materials, the composite ferromolybdenum alloy melt containing vanadium and rhenium is obtained by smelting using the furnace-external aluminothermic reduction method. After further processing, the composite ferromolybdenum alloy intermediate containing vanadium and rhenium is obtained.

[0029] The present invention first leaches molybdenum concentrate in a sulfur-phosphorus mixed acid system to obtain a molybdenum-extracted liquid, and then performs extraction treatment to obtain an organic phase loaded with molybdenum, rhenium, and vanadium.

[0030] In this invention, the molybdenum concentrate, based on elemental mass content, may include Mo: 50%~60%, S: 30%~40%, Re: 15~40 g / t, V: 50~150 g / t; or Mo: 52%~58%, S: 32%~38%, Re: 20~35 g / t, V: 70~130 g / t; or Mo: 54%~56%, S: 34%~36%, Re: 25~30 g / t, V: 90~110 g / t.

[0031] In this invention, the concentration of sulfuric acid in the sulfuric-phosphoric acid mixed acid system can be 0.5~2 mol / L, 0.8~1.7 mol / L, or 1.1~1.4 mol / L, and the concentration of phosphoric acid can be 1~2.5 mol / L, 1.3~2.2 mol / L, or 1.6~1.9 mol / L.

[0032] In this invention, the leaching time can be 1~4 h, 1.5~3.5 h, or 2.0~2.5 h.

[0033] In this invention, the leaching temperature can be 70~120℃, 80~110℃, or 90~100℃.

[0034] In this invention, the liquid-to-solid ratio of the leaching can be 5~15L / kg, 7~13L / kg, or 9~11L / kg.

[0035] In this invention, the concentration of iron in the molybdenum extraction solution can be 100~130 mg / L, 105~125 mg / L, or 110~120 mg / L.

[0036] In this invention, the concentration of vanadium in the molybdenum extraction solution is 150~180 g / L; In this invention, the concentration of copper in the molybdenum extraction solution can be 6000~7500 mg / L, 6300~7200 mg / L, or 6600~6900 mg / L.

[0037] In this invention, the concentration of rhenium in the molybdenum extraction solution can be 40~60 mg / L, 44~56 mg / L, or 48~52 mg / L.

[0038] In this invention, the concentration of residual molybdenum in the molybdenum extraction solution can be 1000~3000 mg / L, 1400~2600 mg / L, or 1800~2200 mg / L.

[0039] In this invention, the extractant used in the extraction process preferably includes an amine extractant. Specifically, the amine extractant can be Aliquat 336 / N263.

[0040] In this invention, the volume concentration of the extractant can be 5%~40%, 10%~35%, 15%~30%, or 20%~25%.

[0041] In this invention, the volume ratio of the organic phase to the aqueous phase in the extraction process can be (5~1):(1~2), (4.5~1.5):(1.2~1.8), or (4~2):(1.4~1.6).

[0042] In this invention, the extraction temperature can be 15~50℃, 20~45℃, 25~40℃, or 30~35℃.

[0043] In this invention, the extraction time can be 5-30 min, 10-25 min, or 15-20 min.

[0044] In this invention, the organic phase loaded with molybdenum, rhenium, and vanadium obtained in the above steps is back-extracted with ammonia water to obtain a mixed solution containing molybdenum, rhenium, vanadium, and ammonium.

[0045] In this invention, the mass concentration of the ammonia water can be 5%~15%, 7%~13%, or 9%~11%.

[0046] In this invention, during the back-extraction, the volume ratio of the oil phase to the water phase can be (5~1):(1~2), (4.5~1.5):(1.2~1.8), or (4~2):(1.4~1.6).

[0047] In this invention, the temperature of the back-extraction can be 20~60℃, 25~55℃, 30~50℃, or 35~45℃.

[0048] In this invention, the back-extraction time can be 5-30 min, 10-25 min, or 15-20 min.

[0049] In this invention, the vanadium and rhenium-containing composite ferromolybdenum master alloy is preferably a master alloy for alloy steel.

[0050] The present invention then crystallizes and calcines the mixed solution containing molybdenum, rhenium, vanadium and ammonium obtained in the above steps to obtain a composite oxide containing molybdenum oxide, rhenium oxide and vanadium oxide.

[0051] In this invention, the calcination temperature can be 450~600℃, 480~570℃, or 510~540℃.

[0052] In this invention, the roasting time can be 2 to 4 hours, 2.4 to 3.6 hours, or 2.8 to 3.2 hours.

[0053] In this invention, the mass content of molybdenum oxide in the composite oxide can be 60%~80%, 64%~76%, or 68%~72%.

[0054] In this invention, the mass content of rhenium oxide in the composite oxide can be 0.05%~0.5%, 0.15%~0.4%, or 0.25%~0.3%.

[0055] In this invention, the mass content of vanadium oxide in the composite oxide can be 1%~5%, 1.5%~4.5%, 2%~4%, or 2.5%~3.5%.

[0056] Finally, the composite oxide, ferrosilicon, aluminum powder and other ingredients obtained in the above steps are used as raw materials and smelted by the furnace-external aluminothermic reduction method to obtain a vanadium- and rhenium-containing composite ferromolybdenum alloy melt. After post-processing, a vanadium- and rhenium-containing composite ferromolybdenum master alloy is obtained.

[0057] In this invention, the ingredients preferably include one or more of steel scrap, iron scale, saltpeter and slag-forming agent, more preferably steel scrap, iron scale, saltpeter or slag-forming agent.

[0058] In this invention, the raw materials, by mass parts, may include: 100 parts by weight of composite molybdenum oxide; 15-25 parts by weight of ferrosilicon; 25-40 parts by weight of aluminum powder; 10-20 parts by weight of steel scrap; Iron scale, 5-15 parts by weight; Saltpeter, 5-12 parts by weight; Slag-forming agent: 10-18 parts by weight.

[0059] Specifically, the amount of ferrosilicon added can be 15-25 parts by weight, 17-23 parts by weight, or 19-21 parts by weight.

[0060] The amount of aluminum powder added can be 25-40 parts by weight, 28-37 parts by weight, or 31-34 parts by weight.

[0061] The amount of steel chips added can be 10-20 parts by weight, 12-18 parts by weight, or 14-16 parts by weight.

[0062] The amount of iron scale added can be 5-15 parts by weight, 7-13 parts by weight, or 9-11 parts by weight.

[0063] The amount of saltpeter added can be 5-12 parts by weight, 6-11 parts by weight, 7-10 parts by weight, or 8-9 parts by weight.

[0064] The amount of the slag-forming agent added can be 10-18 parts by weight, 11-17 parts by weight, 12-16 parts by weight, or 13-15 parts by weight.

[0065] In this invention, the slag-forming agent can be a mixture of fluorite (CaF2) and lime (CaO). The mass ratio of the two can be 1:1 to 2:1.

[0066] In this invention, the external silicon-aluminum thermal reduction method preferably adopts a bottom ignition method.

[0067] In this invention, the smelting time can be 3-8 minutes, 4-7 minutes, or 5-6 minutes.

[0068] In this invention, the smelting temperature can be 1850~2100℃, or 1900~2050℃, or 1950~2000℃.

[0069] In this invention, the time for the melt to stand and separate into layers after smelting can be 10-20 min, 12-18 min, or 14-16 min.

[0070] In this invention, the post-processing preferably includes crushing and screening steps; In this invention, the vanadium and rhenium-containing composite ferromolybdenum contains Mo at a mass content of 55%~65%, 57%~63%, or 59%~61%, V at a mass content of 1.0%~4.5%, 1.5%~4.0%, 2.0%~3.5%, or 2.5%~3.0%, Re at a mass content of 0.05%~0.4%, 0.1%~0.35%, 0.15%~0.3%, or 0.2%~0.25%, and Fe and unavoidable impurities.

[0071] This invention provides the application of the vanadium and rhenium-containing composite ferromolybdenum master alloy prepared by any of the above technical solutions in the preparation of alloy steel to increase the proportion of spheroidized vanadium carbide and / or type 11 vanadium carbide in alloy steel.

[0072] In this invention, the mass ratio of the vanadium and rhenium-containing composite ferromolybdenum in the alloy steel melt can be 0.5%~3.0%, 1.0%~2.5%, or 1.5%~2.0%.

[0073] In this invention, the vanadium content in the alloy steel can be 0.05%~0.25%, 0.09%~0.21%, or 0.13%~0.17%.

[0074] In this invention, the molybdenum content in the alloy steel can be 0.3%~1.5%, 0.5%~1.3%, or 0.7%~1.1% by mass.

[0075] In this invention, the rhenium content in the alloy steel can be 0.001%~0.01%, 0.003%~0.008%, or 0.005%~0.006%.

[0076] In this invention, the average particle size of vanadium carbide particles in the alloy steel can be less than or equal to 2 μm, less than or equal to 1.5 μm, or less than or equal to 1 μm.

[0077] In this invention, the vanadium carbide particles in the alloy steel are preferably distributed in a spherical morphology.

[0078] In this invention, the volume fraction of type 11 vanadium carbide in the alloy steel preferably accounts for more than 60% of the total vanadium carbide, more preferably more than 70% of the total vanadium carbide, and even more preferably more than 80% of the total vanadium carbide.

[0079] This invention addresses the high cost and significant resource loss of rhenium and ferrovanadium associated with molybdenum concentrate in existing alloy steel strengthening processes, which involve the single addition of ferrovanadium, ferromolybdenum, and ferrhenium. It provides a low-cost, high-performance solution. The method includes: synergistic extraction of molybdenum concentrate solution after sulfur-phosphorus acid extraction, simultaneously recovering molybdenum and rhenium while selectively extracting vanadium; obtaining a composite molybdenum oxide containing MoO3, Re2O7, and V2O5 through back-extraction and roasting; preparing a vanadium- and rhenium-containing composite ferromolybdenum master alloy via a one-step ladle aluminothermic reduction method; and finally adding this composite ferromolybdenum to the alloy steel. Utilizing the spheroidizing and refining effects of molybdenum and rhenium on the morphology of vanadium carbide precipitation and their stabilizing effect on high-hardness type 11 vanadium carbide, the strength, toughness, and wear life of the alloy steel are significantly improved. This invention achieves the resource utilization of the rare metal rhenium, significantly improving the performance of alloy steel without significantly increasing costs.

[0080] This invention aims to complete and refine the overall technical solution, better ensure the composition and proportion of vanadium- and rhenium-containing composite ferromolybdenum master alloy, and improve the stability and efficiency of the processing technology, thereby further enhancing the recovery efficiency of vanadium- and rhenium-containing composite ferromolybdenum master alloy and the performance of the alloy steel. Specifically, the preparation method of the aforementioned vanadium- and rhenium-containing composite ferromolybdenum reinforced alloy steel may include the following: A method for preparing vanadium- and rhenium-containing composite molybdenum-iron reinforced alloy steel includes the following steps: S1. The molybdenum concentrate solution after sulfur-phosphorus acid extraction is subjected to extraction treatment. An extractant with synergistic extraction ability for molybdenum and rhenium is used to simultaneously extract molybdenum and rhenium from the solution and selectively extract vanadium to obtain an organic phase loaded with molybdenum, rhenium and vanadium. S2. The organic phase loaded with molybdenum, rhenium, and vanadium is back-extracted with ammonia water, so that molybdenum and rhenium are transferred into the aqueous phase in the form of ammonium salts, to obtain a mixed solution containing ammonium molybdate, ammonium rheniumate, and ammonium vanadate.

[0081] S3. The mixed solution obtained in step S2 is crystallized and calcined to obtain a composite molybdenum oxide containing MoO3, Re2O7 and V2O5; S4. The composite molybdenum oxide obtained in step S3 is mixed with ferrosilicon, aluminum powder, steel scrap, iron scale, saltpeter and slag-forming agent in proportion, and loaded into the furnace. The furnace is then smelted using the external silicon-aluminothermic reduction method to obtain a composite molybdenum-iron alloy melt containing vanadium and rhenium. S5. Cool, crush, and sieve the melt to obtain vanadium- and rhenium-containing composite ferromolybdenum.

[0082] S6. The vanadium- and rhenium-containing composite ferromolybdenum obtained in step S5 is added to alloy steel in a certain proportion to prepare vanadium carbide reinforced alloy steel.

[0083] Specifically, in the molybdenum extraction solution described in step S1, the iron concentration is 100-130 mg / L, the vanadium concentration is 150-180 mg / L, the copper concentration is 6000-7500 mg / L, the rhenium concentration is 40-60 mg / L, and the residual molybdenum concentration is 1000-3000 mg / L.

[0084] Specifically, in step S1, the extractant is an amine extractant.

[0085] Specifically, in step S1, the extraction process conditions are as follows: the extractant concentration is 5%-40%, the extraction ratio is 5:1 to 1:2, the extraction temperature is 15-50℃, and the extraction time is 5-30 min.

[0086] Specifically, in step S2, the concentration of the ammonia water is 5-15%, the desorption ratio (O / A) is 5:1 to 1:2, and the desorption temperature is 20-60℃.

[0087] Specifically, the calcination temperature in step S3 is 450℃~600℃, the calcination time is 2~4 hours, and the resulting composite molybdenum oxide contains 60%~80% MoO3, 0.05%~0.5% Re2O7, and 1%~5% V2O5.

[0088] Specifically, the weight ratio of each component in step S4 is as follows: 100 parts of composite molybdenum oxide, 15-25 parts of ferrosilicon, 25-40 parts of aluminum powder, 10-20 parts of steel scrap, 5-15 parts of iron scale, 5-12 parts of nitrate, and 10-18 parts of slag-forming agent.

[0089] Specifically, the furnace-side silicon-aluminum thermal reduction method described in step S4 uses a bottom ignition method, with a smelting reaction time of 3-8 minutes and a melt settling and stratification time of 10-20 minutes.

[0090] Specifically, in the vanadium- and rhenium-containing composite ferromolybdenum obtained in step S5, the Mo content is 55%~65%, the V content is 1.0%~4.5%, the Re content is 0.05%~0.4%, and the balance is Fe and unavoidable impurities.

[0091] Specifically, in step S6, the amount of vanadium- and rhenium-containing composite ferromolybdenum added is 0.5% to 3.0% of the melt weight of the alloy steel, so that the final vanadium content in the alloy steel is 0.05% to 0.25%, the molybdenum content is 0.3% to 1.5%, and the rhenium content is 0.001% to 0.01%.

[0092] Specifically, in the vanadium carbide reinforced alloy steel obtained in step S6, the average particle size of vanadium carbide particles is less than 2 μm, and the vanadium carbide particles are distributed in a spherical shape, wherein the volume fraction of type 11 vanadium carbide accounts for more than 60% of the total vanadium carbide.

[0093] The present invention provides a method for preparing a vanadium-rhenium composite ferromolybdenum master alloy and its application, namely, a method for preparing vanadium-rhenium composite ferromolybdenum reinforced alloy steel. This invention proposes a technical route that involves the synergistic extraction of molybdenum, rhenium, and vanadium from a molybdenum concentrate metallurgical solution followed by one-step aluminothermic reduction to prepare a low-cost vanadium-rhenium composite ferromolybdenum, which is then applied to strengthen alloy steel, thereby fully leveraging the morphology and phase structure regulation effects of vanadium carbide. This route overcomes the limitations of traditional high-cost single ferroalloy additions, achieving comprehensive utilization and efficient recovery of molybdenum, rhenium, and vanadium resources. Furthermore, it allows the simultaneous addition of these three elements in the form of a composite ferromolybdenum to alloy steel, fully utilizing their synergistic strengthening effect, thus achieving an organic unity between comprehensive resource utilization and the preparation of high-performance wear-resistant materials.

[0094] This invention presents a novel, resource-efficient process for preparing vanadium-rhenium composite ferromolybdenum using a short-process "synergistic extraction-co-reduction" method. This invention abandons the complex separation routes of existing technologies that pursue high-purity single metal salts. Instead, it innovatively utilizes an extractant with synergistic effects on molybdenum and rhenium to simultaneously recover molybdenum and rhenium in a single extraction step, while selectively co-extracting vanadium. Subsequently, a naturally proportioned composite oxide containing MoO3, R2O7, and V2O5 is obtained through direct calcination, followed by a one-step aluminothermic reduction process to produce a vanadium-rhenium composite ferromolybdenum alloy. This process not only eliminates the high cost of complete separation of molybdenum, rhenium, and vanadium but also transforms the rhenium and vanadium resources lost in traditional processes into valuable resources. It provides an unprecedented low-cost molybdenum-rhenium-vanadium composite additive carrier for downstream alloy steels, solving the industry problem of high costs associated with using rhenium-ferromolybdenum alone. Meanwhile, this invention, for the first time, achieves synergistic regulation of vanadium carbide in alloy steel through low-cost composite ferromolybdenum. It utilizes molybdenum, rhenium, and vanadium from the self-made composite ferromolybdenum to replace the expensive single ferromolybdenum, ferrovanadium, and rhenium ferromanganese used in traditional processes. When this composite ferromolybdenum is added to the alloy steel melt, vanadium acts as a carbide formation source, resulting in the precipitation of a large number of dispersed vanadium carbide particles. The synergistic effect of molybdenum and rhenium during precipitation promotes significant spheroidization and refinement of the vanadium carbide particles, preventing sharp-edged carbides from cutting the matrix. More importantly, the composite effect of molybdenum and rhenium promotes the preferential and abundant formation of high-hardness, high-stability type 11 vanadium carbide, suppressing the occurrence of other inefficient carbides.

[0095] This invention resolves the fundamental contradiction between improving the performance and controlling the cost of alloy steel in mining through a resource recycling approach. It does not increase the additional cost of rhenium metal procurement, but instead extracts valuable elements from metallurgical wastewater from molybdenum concentrate. This makes the cost of the prepared vanadium-rhenium composite ferromolybdenum significantly lower than that of a mixture of ferrovanadium, ferromolybdenum, and ferrhenium. When applied to mining alloy steels (such as large crusher liners, mill liners, and gyratory liners), it significantly improves the wear life and impact resistance of the alloy steel by maximizing the fine-grain strengthening and carbide spheroidization strengthening effects, while maintaining or even slightly reducing material costs. This invention provides a disruptive technological solution that combines economy and high performance for fields such as mining and building materials that are extremely cost-sensitive yet seek the ultimate wear life.

[0096] To further illustrate the present invention, the following detailed description of the preparation method and application of a vanadium-rhenium composite molybdenum-iron master alloy provided by the present invention is provided in conjunction with embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, and are not intended to limit the technical solution of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0097] Example 1: Preparation of vanadium- and rhenium-containing composite ferromolybdenum master alloy and its application in 42CrMo steel.

[0098] (1) Preparation of intermediate alloy.

[0099] Molybdenum concentrate composition: Mo 55.3%, S 36.1%, Re 28 g / t, V 110 g / t.

[0100] Leaching: A mixed sulfuric-phosphoric acid system was used, with sulfuric acid concentration of 1.2 mol / L, phosphoric acid concentration of 1.8 mol / L, and a liquid-to-solid ratio of 10 L / kg. Leaching was carried out at 90℃ for 2.5 h to obtain the molybdenum-extracted solution. The concentrations of major elements in the molybdenum-extracted solution were: Fe 115 mg / L, V 168 g / L, Cu 6800 mg / L, Re 48 mg / L, and Mo 1800 mg / L.

[0101] Extraction: Using N235 amine extractant with a volume concentration of 20% as the extractant, the organic phase to water phase volume ratio was 2:1, and extraction was carried out at 35℃ for 20 min to obtain an organic phase loaded with molybdenum, rhenium and vanadium.

[0102] Back-extraction: Back-extraction was performed using 10% ammonia water at an oil-to-water volume ratio of 2:1, at a temperature of 45℃, for 15 minutes, to obtain a mixed solution containing molybdenum, rhenium, vanadium, and ammonium.

[0103] Crystallization and calcination: After evaporation and crystallization, the mixed solution was calcined at 520℃ for 3 hours to obtain composite oxide powder. Its composition is: MoO3 73.5%, V2O5 2.8%, Re2O7 0.18%, with the balance being impurities.

[0104] Ingredients: 100kg composite oxide, 20kg ferrosilicon (containing 75% Si), 30kg aluminum powder, 15kg steel scrap, 10kg iron scale, 8kg saltpeter, 15kg slag-forming agent (fluorite to lime mass ratio 1.5:1).

[0105] Aluminothermic reduction outside the furnace: A bottom ignition method is used, with a smelting temperature of approximately 1980℃, a reaction time of 5 minutes, and the melt is allowed to settle and separate into layers for 15 minutes. After cooling, it is crushed and sieved to obtain a vanadium-rhenium composite ferromolybdenum master alloy. Its chemical composition is: Mo 60.8%, V 2.5%, Re 0.14%, with the balance being Fe and unavoidable impurities.

[0106] (2) Preparation of 42CrMo steel.

[0107] 42CrMo steel was smelted in a 500kg medium-frequency induction furnace. The basic molten steel composition was: C 0.40%, Si 0.25%, Mn 0.70%, Cr 1.05%, Mo 0.20%, P≤0.020%, S≤0.015%. When the molten steel temperature reached 1650℃, the above-mentioned composite ferromolybdenum master alloy was added at 1.2% of the molten steel mass to achieve the target composition of: Mo 0.60%, V 0.08%, Re 0.0017%. After alloying, the steel was refined by argon blowing for 5 minutes, cast into Φ80mm ingots, and then forged into Φ20mm bars. The heat treatment process was: oil quenching at 850℃ + tempering at 560℃ and air cooling.

[0108] The 42CrMo steel prepared in Example 1 of this invention was characterized and its performance was tested.

[0109] See Figure 1 , Figure 1 This is a microstructure diagram of the 42CrMo steel prepared in Example 1 of the present invention.

[0110] Depend on Figure 1 It can be seen that the microstructure of chromium-molybdenum steel is mainly fine tempered sorbite. Many fine needle-like and feather-like structures are interspersed in the microstructure. After tempering, some martensite decomposes and fine carbides precipitate. The carbides are evenly distributed in the microstructure, and no chain-like or angular vanadium carbide is found.

[0111] Example 2: Application of vanadium- and rhenium-containing composite ferromolybdenum master alloy in 60Cr6MnSiMo medium chromium alloy steel.

[0112] One L of the molybdenum extraction solution, containing 2000 mg / L molybdenum, 100 mg / L rhenium, and 170 mg / L vanadium, was extracted for 20 min at 25 °C using 10% trialkylphosphine oxide-kerosene as the extractant at a ratio O / A = 1:2. The supported organic phase was then back-extracted with 8% ammonia at an O / A = 1:1 ratio at 50 °C to obtain a mixed ammonium salt solution of molybdenum, rhenium, and vanadium, with recoveries of 97.5%, 95.8%, and 93.2%, respectively.

[0113] (1) Preparation of intermediate alloy.

[0114] Using the same preparation process as in Example 1, only the calcination temperature was adjusted to 580℃, the resulting composite oxide composition was: MoO3 76.2%, V2O5 3.1%, Re2O7 0.25%. A composite ferromolybdenum master alloy was obtained using the same smelting process, with the composition: Mo 59.5%, V 3.0%, Re 0.18%, and the remainder Fe.

[0115] (2) Preparation of 60Cr6MnSiMo steel.

[0116] 60Cr6MnSiMo medium-chromium alloy steel with the target composition was smelted in an intermediate frequency furnace. The base molten steel was controlled to have the following composition: C 0.58%, Si 0.60%, Mn 1.05%, Cr 5.95%, and Mo 0.45%. Before tapping, the above-mentioned intermediate alloy was added at 2.0% of the molten steel mass to achieve the following composition: Mo 1.05%, V 0.15%, and Re 0.0036%. After casting at 1600℃, the steel was oil quenched at 950℃ for 1 hour and then tempered at 550℃ for 2 hours.

[0117] The 60Cr6MnSiMo medium chromium alloy steel prepared in Example 2 of this invention was characterized and its performance was tested.

[0118] See Figure 2 , Figure 2 This is a microstructure diagram of the medium-chromium alloy steel prepared in Example 2 of the present invention.

[0119] Depend on Figure 2 It can be seen that the microstructure formed after tempering medium-chromium alloy steel at 550℃ mainly contains tempered sorbite and granular carbides. The precipitation and distribution of a large number of granular and feathery carbides within the matrix significantly improves impact toughness and wear resistance.

[0120] Example 3: 1 L of the molybdenum extraction solution, containing 2000 mg / L molybdenum, 100 mg / L rhenium, and 170 mg / L vanadium, was extracted for 10 min using a 30% mixed amine extractant at a ratio O / A = 3:1 and a temperature of 40°C. The supported organic phase was back-extracted with 12% ammonia water at an O / A = 3:1 ratio and a temperature of 30°C, yielding a mixed solution of ammonium molybdate, ammonium rheniumate, and ammonium vanadate. The recoveries of molybdenum, rhenium, and vanadium were 98.8%, 97.1%, and 95.3%, respectively.

[0121] Comparative Example 1: Ordinary 42CrMo steel.

[0122] For comparison, a batch of ordinary 42CrMo steel without rhenium- and vanadium-containing composite ferromolybdenum master alloy was smelted. Under the same smelting conditions, conventional ferromolybdenum (60% Mo) and ferrovanadium (50% V) were used to adjust the Mo content in the steel to 0.60% and V to 0.08%, but rhenium was not included. The remaining composition, forging, and heat treatment processes were exactly the same as in Example 1.

[0123] See Figure 3 , Figure 3 This is a comparison diagram of the impact toughness of alloy steels prepared in the embodiments and comparative examples of the present invention.

[0124] The preparation method of vanadium- and rhenium-containing composite molybdenum-iron reinforced alloy steel provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention. The scope of patent protection of the present invention is defined by the technical solution and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the technical solution, or if they include equivalent structural elements that are not substantially different from the textual description of the technical solution, then these other embodiments should also be included within the scope of the technical solution.

Claims

1. A method for preparing a vanadium- and rhenium-containing composite ferromolybdenum master alloy, characterized in that, Includes the following steps: 1) Molybdenum concentrate is leached in a sulfur-phosphorus mixed acid system to obtain a molybdenum-extracted liquid, which is then extracted to obtain an organic phase loaded with molybdenum, rhenium, and vanadium. 2) After back-extraction of the organic phase loaded with molybdenum, rhenium, and vanadium obtained in the above steps with ammonia water, a mixed solution containing molybdenum, rhenium, vanadium, and ammonium is obtained; 3) The mixed solution containing molybdenum, rhenium, vanadium and ammonium obtained in the above steps is crystallized and calcined to obtain a composite oxide containing molybdenum oxide, rhenium oxide and vanadium oxide; 4) Using the composite oxide, ferrosilicon, aluminum powder and other ingredients obtained in the above steps as raw materials, the composite ferromolybdenum alloy melt containing vanadium and rhenium is obtained by smelting using the furnace-external aluminothermic reduction method. After further processing, the composite ferromolybdenum intermediate alloy containing vanadium and rhenium is obtained.

2. The preparation method according to claim 1, characterized in that, The molybdenum concentrate, by elemental mass content, includes Mo: 50%~60%, S: 30%~40%, Re: 15~40 g / t, and V: 50~150 g / t; In the sulfuric acid-phosphoric acid mixed system, the concentration of sulfuric acid is 0.5~2 mol / L and the concentration of phosphoric acid is 1~2.5 mol / L; The leaching time is 1-4 hours; The leaching temperature is 70~120℃; The liquid-to-solid ratio of the leaching is 5~15L / kg.

3. The preparation method according to claim 1, characterized in that, The concentration of iron in the molybdenum extraction solution is 100-130 mg / L; The concentration of vanadium in the molybdenum extraction solution is 150-180 g / L. The concentration of copper in the molybdenum extraction solution is 6000~7500 mg / L; The concentration of rhenium in the molybdenum extraction solution is 40-60 mg / L; The concentration of residual molybdenum in the molybdenum extraction solution is 1000~3000 mg / L.

4. The preparation method according to claim 1, characterized in that, The extractant used in the extraction process includes amine extractants; The volume concentration of the extractant is 5% to 40%; In the extraction process, the volume ratio of the organic phase to the aqueous phase is (5~1):(1~2); The extraction process is performed at a temperature of 15~50℃; The extraction process takes 5 to 30 minutes.

5. The preparation method according to claim 1, characterized in that, The mass concentration of the ammonia solution is 5%~15%; In the back-extraction, the volume ratio of the oil phase to the water phase is (5~1):(1~2). The temperature for the back-extraction is 20~60℃; The back-extraction time is 5-30 min; The vanadium and rhenium-containing composite ferromolybdenum master alloy is a master alloy used for alloy steel.

6. The preparation method according to claim 1, characterized in that, The roasting temperature is 450~600℃; The roasting time is 2-4 hours; In the composite oxide, the mass content of molybdenum oxide is 60%~80%; In the composite oxide, the rhenium oxide content is 0.05%~0.5% by mass; The vanadium oxide content in the composite oxide is 1% to 5% by mass.

7. The preparation method according to claim 1, characterized in that, The ingredients include one or more of steel scrap, iron scale, saltpeter, and slag-forming agent; The raw materials, by mass parts, include: 100 parts by weight of composite molybdenum oxide; 15-25 parts by weight of ferrosilicon; 25-40 parts by weight of aluminum powder; 10-20 parts by weight of steel scrap; Iron scale, 5-15 parts by weight; Saltpeter, 5-12 parts by weight; Slag-forming agent: 10-18 parts by weight.

8. The preparation method according to claim 1, characterized in that, The external silicon-aluminum thermal reduction method adopts a bottom ignition method; The smelting time is 3-8 minutes; The smelting temperature is 1850~2100℃; After smelting, the melt is allowed to stand and separate into layers for 10-20 minutes. The post-processing includes crushing and screening steps; In the vanadium and rhenium-containing composite ferromolybdenum, the mass content of Mo is 55%~65%, the mass content of V is 1.0%~4.5%, the mass content of Re is 0.05%~0.4%, and Fe and unavoidable impurities are present.

9. The application of the vanadium and rhenium-containing composite ferromolybdenum master alloy prepared by the preparation method according to any one of claims 1 to 8 in the preparation of alloy steel to increase the proportion of spheroidized vanadium carbide and / or type 11 vanadium carbide in the alloy steel.

10. The application according to claim 9, characterized in that, The vanadium- and rhenium-containing composite ferromolybdenum is used in the alloy steel melt at a mass ratio of 0.5% to 3.0%. In the alloy steel, the vanadium content is 0.05%~0.25% by mass; In the alloy steel, the molybdenum content is 0.3% to 1.5% by mass; In the alloy steel, the rhenium content is 0.001%~0.01% by mass; In the alloy steel, the average particle size of vanadium carbide particles is less than or equal to 2 μm; In the alloy steel, vanadium carbide particles are distributed in a spherical morphology; In the alloy steel, the volume fraction of type 11 vanadium carbide accounts for more than 60% of the total vanadium carbide.

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