Low-chromium polyhedral grinding medium and preparation process thereof

Abstract

The invention discloses a low-chromium polyhedral grinding medium and a preparation process thereof, and relates to the technical field of grinding media, the low-chromium polyhedral grinding medium comprises a triangular pyramid core body and a triangular pyramid support fixed outside the triangular pyramid core body, the triangular pyramid support comprises four spheres and six prisms respectively connected between two adjacent spheres, the four spheres are respectively fixed at four vertexes of the triangular pyramid core body, and the six prisms are respectively fixed on six edges of the triangular pyramid core body; the triangular pyramid core body and the triangular pyramid bracket are made of ferrochrome, the chromium content in the triangular pyramid core body is 0.5-1.0%, and the chromium content in the triangular pyramid bracket is 11-15%; according to the grinding medium, impact force and grinding force can efficiently and accurately act on mineral particles, the grinding effect is kept at a high level, and the service life of the grinding medium is long.

Description

Technical Field

[0001] This invention relates to the field of abrasive media technology, specifically to a low-chromium polyhedral abrasive media and its preparation process. Background Technology

[0002] Grinding media are key consumable components in grinding operations in industries such as mineral processing, metallurgy, and building materials. Their performance directly affects grinding efficiency, energy consumption, and production costs. Polyhedral grinding media (such as tetrahedral and triangular pyramid shapes) have unique geometric structures that allow for a combination of impact and grinding actions during mill operation. This helps improve the particle size distribution of ground products and increase the yield of easily sortable intermediate particle sizes, thus attracting attention in the fields of fine and ultrafine grinding.

[0003] Currently, most common multi-faceted grinding media adopt a monolithic design, and to ensure their wear resistance and impact resistance, they are generally made of materials such as high-chromium cast iron or high-chromium alloy steel. Although these materials have high hardness and good wear resistance, their chromium content usually exceeds 10%, even reaching 20%, leading to a significant increase in raw material costs. Especially against the backdrop of tight global chromium resource supply and price fluctuations, the manufacturing cost of high-chromium grinding media remains high, increasing the operational burden on mineral processing enterprises.

[0004] Furthermore, existing tetrahedral grinding media still have certain limitations in structural design and material matching. Due to their uniform material composition, when subjected to complex alternating impacts and grinding loads, stress concentration areas such as sharp corners and edges are prone to early fatigue spalling, microcrack propagation, and even overall fracture, resulting in a short actual service life of the media. Simultaneously, they exhibit poor uniform wear; as usage time increases, their geometry changes irregularly, leading to a significant decrease in grinding efficiency. This necessitates frequent shutdowns for media replenishment or replacement, impacting mill operating rates and production continuity.

[0005] Therefore, how to significantly reduce the dependence on expensive alloying elements, control manufacturing costs, and improve the impact fatigue resistance and uniform wear capability of grinding media while ensuring efficient grinding performance and sufficient service life has become an urgent problem to be solved in this field. Summary of the Invention

[0006] The present invention aims to solve the problems of high manufacturing cost and short service life of existing polyhedral grinding media.

[0007] To address the aforementioned problems, this invention provides a low-chromium polyhedral grinding media, comprising a triangular pyramid core and a triangular pyramid support fixed to the outside of the core. The support comprises four spheres and six prisms connected between adjacent spheres. The four spheres are fixed at the four vertices of the core, and the six prisms are fixed on the six edges of the core. Both the core and support are made of ferrochrome alloy, wherein the chromium content in the core is 0.5-1.0%, and the chromium content in the support is 11-15%.

[0008] The low-chromium polyhedral grinding media provided by this invention has, but is not limited to, the following beneficial effects compared to the prior art: In the low-chromium polyhedral grinding media of this invention, the grinding media is designed as a composite structure of a triangular pyramid core and a triangular pyramid support. The triangular pyramid core, as the main structure, is made of a low-chromium ferrochrome alloy, while the triangular pyramid support, as the key stress-bearing component directly subjected to impact and wear, is made of a high-chromium ferrochrome alloy, thus significantly reducing raw material costs. Simultaneously, since the four spheres of the triangular pyramid support constitute the main point contact impact points between the media, the grinding material, and the grinding equipment liner, its high-chromium material ensures extremely high impact fatigue resistance and fracture resistance. Especially when impacting the equipment liner, because the triangular pyramid core is located within the triangular pyramid support, the surface of the triangular pyramid core is prevented from impacting the equipment liner, greatly reducing the damage rate of the low-chromium triangular pyramid core and ensuring its long service life. Because the six prisms form a line contact grinding surface, the high-chromium material endows it with excellent abrasion resistance. This allows the impact force and grinding force to act efficiently and accurately on the mineral particles, maintaining a high level of grinding effect.

[0009] Furthermore, the point impact of the spheres facilitates the crushing of coarse particles, while the linear grinding of the prisms promotes the generation of intermediate particle sizes. This effectively reduces both the "ungrindable" coarse particles and the "over-grinding" ultrafine particles, increasing the yield of easily selectable intermediate particle sizes. The three-dimensional spatial skeleton-like triangular pyramid support structure is firmly integrated with the triangular pyramid core, resulting in good overall impact resistance and toughness of the grinding media, making it less prone to overall breakage. Simultaneously, after wear, the high-chromium triangular pyramid support exhibits relatively uniform changes in its spherical surface and edges, maintaining a relatively stable grinding profile over a period of time and ensuring stable grinding efficiency. When the media is impacted, the force is transmitted through the high-chromium triangular pyramid support to the entire low-chromium triangular pyramid core, and is evenly dispersed by the three-dimensional structure of the triangular pyramid core. The good toughness of the low-chromium triangular pyramid core effectively absorbs and buffers impact energy, reducing stress concentration within the media and significantly reducing the probability of fatigue cracking and overall breakage, thereby extending the service life of the grinding media.

[0010] Furthermore, the triangular pyramid core is shaped as a regular triangular pyramid, with all four triangular faces being arc surfaces and all six edges being arc edges.

[0011] Furthermore, the four vertices of the triangular pyramid core are all recessed hemispherical grooves, and the six edges are all recessed semi-cylindrical concave rails; the four spheres are respectively embedded in the hemispherical grooves, and the six prisms are respectively embedded in the semi-cylindrical concave rails.

[0012] Furthermore, in S1, the diameter ratio of the sphere to the prism in the triangular pyramid support is 2:1.

[0013] Furthermore, the raw materials of the ferrochrome alloy of the triangular pyramid core, by mass percentage, include: C: 0.8-1.2%, Si: 0.3-0.8%, Mn: 0.5-1.0%, Cr: 0.5-1.0%, with the balance being Fe and unavoidable impurities.

[0014] Furthermore, the raw materials of the ferrochrome alloy of the triangular pyramid support 200, by mass percentage, include: C: 2.0-3.0%, Si: ≤1.0%, Mn: 0.5-1.5%, Cr: 11-15%, Mo: 0.5-1.5%, with the balance being Fe and unavoidable impurities.

[0015] Furthermore, the triangular pyramid core and the triangular pyramid support are fixedly connected by a metallurgical bonding method, and an inter-fusion diffusion layer is formed at the connection interface.

[0016] The present invention also discloses a preparation process for preparing the low-chromium polyhedral abrasive media as described above, comprising the following steps: S1. Use drafting software to draw model diagrams of the triangular pyramid core and the triangular pyramid support. Based on the model diagrams, make individual molds of the triangular pyramid support and overall molds of the triangular pyramid core and the triangular pyramid support combined. S2. Add the raw material of the ferrochrome alloy of the triangular pyramid support to the furnace according to the mass percentage and melt it into high ferrochrome molten iron. Then pour it into the single mold, cool it and demold it to obtain the triangular pyramid support. S3. Add the raw material of ferrochrome alloy of triangular pyramid core to the furnace according to the mass percentage and melt it into low-chromium molten iron. Place the triangular pyramid support in the integral mold and fit it in. Then pour the low-chromium molten iron into the integral mold, and demold it after cooling to obtain the medium blank. S4. The media blank is quenched and tempered in sequence to obtain a low-chromium polyhedral grinding media.

[0017] The present invention provides a low-chromium polyhedral grinding media preparation process, which, compared with the prior art, has the following beneficial effects, but is not limited to: The manufacturing process of this invention breaks down the production of complex composite components into two relatively simple casting steps, offering significant industrial advantages. First, step-by-step casting allows for separate optimization of the melting and casting process parameters for the high-chromium support and the low-chromium core, ensuring optimal internal quality for each and avoiding defects such as hot cracking and shrinkage porosity caused by significant differences in shrinkage rate and thermal conductivity between the two alloys during integral casting. Second, the strategy of prefabricating the triangular pyramid support and then integrally molding the composite structure utilizes the second pour of low-chromium molten iron to simultaneously achieve two functions: forming the core body and completing the metallurgical bond with the support. This method features a short process flow, conventional equipment requirements, strong process controllability, and high yield, making it highly suitable for large-scale, low-cost, high-quality, and stable production.

[0018] Furthermore, in S4, the quenching process is as follows: the medium blank is placed in a heating furnace, heated to 950-1050℃, held for more than 1 hour, and then air-cooled to room temperature.

[0019] Specifically, the austenitizing temperature range of 950-1050℃ ensures that a large number of carbides in the high-chromium triangular pyramid support can be fully dissolved, allowing carbon and alloying elements to be uniformly integrated into the austenite, laying the foundation for obtaining high-hardness martensite in the future. For the low-chromium triangular pyramid core, this temperature is also sufficient to complete austenitizing. Holding at this temperature for more than 1 hour ensures that the heat can penetrate fully and achieve a uniform microstructure. Air cooling can reduce the cooling rate and prevent the low-chromium triangular pyramid core from cracking due to excessively rapid cooling. At the same time, it ensures that the high-carbon, high-chromium material obtains higher hardness and a deeper hardened layer, thereby maximizing the wear resistance of the surface of the triangular pyramid support.

[0020] Furthermore, in S4, the tempering process is as follows: the quenched medium blank is placed in a heating furnace, heated to 200-350℃, held for 2-4 hours, and then air-cooled.

[0021] Specifically, holding the medium at 200-350℃ for 2.4 hours can effectively promote the tempering transformation of the extremely unstable, high-stress martensite formed by quenching, precipitating fine carbides, while greatly eliminating or homogenizing the internal residual stress. This avoids the risk of spontaneous cracking of the medium due to stress release during storage, transportation, or initial loading. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the structure of the low-chromium polyhedral grinding media of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the triangular pyramid support in the low-chromium polyhedral grinding media of Embodiment 1 of the present invention; Figure 3This is a schematic diagram of the triangular pyramid core in the low-chromium polyhedral grinding media of Embodiment 1 of the present invention.

[0024] In the diagram: 100, triangular pyramid core; 200, triangular pyramid support; 201, sphere; 202, prism. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0027] Example 1

[0028] Please see Figure 1-2 This embodiment discloses a low-chromium polyhedral grinding media, including a triangular pyramid core 100 and a triangular pyramid support 200 fixed to the outside of the triangular pyramid core 100. The triangular pyramid support 200 includes four spheres 201 and six prisms 202 respectively connected between two adjacent spheres 201. The four spheres 201 are respectively fixed at the four vertices of the triangular pyramid core 100, and the six prisms 202 are respectively fixed on the six edges of the triangular pyramid core 100. Both the triangular pyramid core 100 and the triangular pyramid support 200 are made of ferrochrome alloy, wherein the chromium content in the triangular pyramid core 100 is 0.5-1.0%, and the chromium content in the triangular pyramid support 200 is 11-15%.

[0029] Specifically, the grinding media is designed as a composite structure of a triangular pyramidal core 100 and a triangular pyramidal support 200. The triangular pyramidal core 100, as the main structure, uses a low-chromium ferrochrome alloy, while the triangular pyramidal support 200, as the key stress-bearing component directly subjected to impact and wear, uses a high-chromium ferrochrome alloy, thus significantly reducing raw material costs. Simultaneously, since the four spheres 201 of the triangular pyramidal support 200 constitute the main point contact impact points between the grinding media, the abrasive, and the grinding equipment liner, its high-chromium material ensures... It exhibits extremely high impact fatigue resistance and fracture resistance; especially when impacting the equipment liner, since the triangular pyramid core 100 is located inside the triangular pyramid support 200, the surface of the triangular pyramid core 100 can be prevented from impacting the equipment liner, greatly reducing the damage rate of the low-chromium triangular pyramid core 100 and ensuring that its low-chromium material can maintain a long service life; since the six prisms 202 form a line contact grinding surface, the high-chromium material gives it excellent wear resistance; thus, the impact force and grinding force can act on the mineral particles efficiently and accurately, and the grinding effect is maintained at a high level.

[0030] Furthermore, the point impact of the sphere 201 is beneficial for coarse particle crushing, while the linear grinding of the prism 202 is beneficial for the generation of intermediate particle sizes. This can more effectively reduce the amount of coarse particles that cannot be ground finely and the amount of ultra-fine particles that are over-ground, thereby increasing the yield of easily selectable intermediate particle sizes. The three-dimensional spatial skeleton-type triangular pyramid support 200 is firmly integrated with the triangular pyramid core 100, resulting in good overall impact resistance and toughness of the grinding media, making it less prone to overall breakage. At the same time, after the high-chromium triangular pyramid support 200 wears, the changes in its spherical surface and edges are relatively uniform, which can maintain a relatively stable grinding profile for a period of time and maintain stable grinding efficiency. When the media is impacted, the force is transmitted through the high-chromium triangular pyramid support 200 to the entire low-chromium triangular pyramid core 100, and is evenly dispersed by the three-dimensional structure of the triangular pyramid core 100. The good toughness of the low-chromium triangular pyramid core 100 can effectively absorb and buffer impact energy, reduce stress concentration inside the media, thereby significantly reducing the probability of fatigue cracking and overall breakage of the media, and thus extending the service life of the grinding media.

[0031] Meanwhile, due to the high grinding efficiency and good product particle size characteristics of this grinding media, the grinding time can be shortened or the mill operating power can be reduced when the same grinding fineness requirements are achieved, thus directly reducing power consumption. The extended service life of the media directly reduces the amount of media consumed per unit of ore processed, reduces the frequency of downtime for media replenishment, and improves equipment operating rate.

[0032] Optionally, the triangular pyramid core 100 is shaped as a regular triangular pyramid, with all four triangular faces being arc surfaces and all six edges being arc edges.

[0033] In this embodiment, the distance between two adjacent vertices of the triangular pyramid core 100 is 60mm.

[0034] Specifically, the symmetry of the regular triangular pyramid ensures the uniformity of force distribution when the media tumbles within the mill. By rounding or sculpting all faces and edges, sharp corners are eliminated. This results in an extremely uniform stress distribution on the media surface, preventing premature spalling or cracking caused by stress concentration at sharp corners, and greatly improving the fatigue resistance of the media. On the other hand, the smooth and continuous curved surface significantly reduces unnecessary high-stress point contacts between media, reducing ineffective metal wear and thus extending the service life of the media and mill liners. In addition, the curved structure also facilitates smooth slurry flow, reduces adhesion, and indirectly improves grinding efficiency.

[0035] Optionally, please refer to Figure 3 The four vertices of the triangular pyramid core 100 are all recessed hemispherical grooves, and the six edges are all recessed semi-cylindrical grooves; the four spheres 201 are respectively embedded in the hemispherical grooves, and the six prisms 202 are respectively embedded in the semi-cylindrical grooves.

[0036] In this embodiment, the hemispherical groove has the same diameter as the sphere 201, and the semi-cylindrical groove has the same diameter as the prism 202 to ensure a complete fit.

[0037] Specifically, the hemispherical groove and the semi-cylindrical groove form a positioning track, and the sphere 201 and the prism 202 fit and match it; this large-area, high-fitting interface can transmit and disperse stress through the huge contact area when subjected to complex and multi-dimensional impact and grinding forces, effectively preventing the triangular pyramid support 200 from fretting wear or displacement, which is an important guarantee for achieving structural reinforcement.

[0038] Optionally, in S1, the diameter ratio of the sphere 201 to the prism 202 in the triangular pyramid support 200 is 2:1.

[0039] In this embodiment, the diameter of the sphere 201 is 7 mm, and the diameter of the prism 202 is 3.5 mm.

[0040] Specifically, the diameter of the sphere 201, which serves as the main impact point, is designed to be twice the diameter of the prism 202, which bears the grinding action. The larger sphere 201 ensures that it has sufficient mass and inertia, enabling it to carry greater kinetic energy during free fall impact and effectively crush coarser mineral particles. At the same time, the larger sphere diameter also means a higher wear-resistant volume reserve. Meanwhile, the relatively smaller diameter of the prism 202 increases the area of ​​line contact grinding while ensuring sufficient strength, thereby improving the efficiency of fine grinding and fine grinding. The 2:1 ratio balances the strength ratio of the two action mechanisms of impact crushing and fine grinding, so that the comprehensive performance of the grinding media reaches the optimal level.

[0041] Optionally, the raw materials of the ferrochrome alloy of the triangular pyramid core 100, by mass percentage, include: C: 0.8-1.2%, Si: 0.3-0.8%, Mn: 0.5-1.0%, Cr: 0.5-1.0%, with the balance being Fe and unavoidable impurities.

[0042] In this embodiment, the raw materials of the ferrochrome alloy of the triangular pyramid core 100, by mass percentage, include: C: 1%, Si: 0.5%, Mn: 0.8%, Cr: 0.8%, with the balance being Fe and unavoidable impurities.

[0043] Specifically, the moderate carbon content ensures that the triangular pyramid core 100 achieves good basic strength after heat treatment; the low chromium content is key to cost control, and this chromium can dissolve in ferrite, playing a certain role in solid solution strengthening; the combination of silicon and manganese mainly plays a role in deoxidation and solid solution strengthening during the smelting process, and helps to improve hardenability. The core advantage of this formula is that, while meeting the sufficient strength required for the triangular pyramid core 100 to serve as a structural support, it maximizes the toughness and plasticity of the material, enabling it to effectively absorb and buffer the impact energy transmitted from the triangular pyramid support 200, preventing overall brittle fracture, which is the foundation of the impact resistance reliability of the entire grinding media.

[0044] Optionally, the raw materials of the ferrochrome alloy of the triangular pyramid support 200, by mass percentage, include: C: 2.0-3.0%, Si: ≤1.0%, Mn: 0.5-1.5%, Cr: 11-15%, Mo: 0.5-1.5%, with the balance being Fe and unavoidable impurities.

[0045] In this embodiment, the raw materials of the ferrochrome alloy of the triangular pyramid support 200, by mass percentage, include: C: 2.5%, Si: 0.5%, Mn: 1%, Cr: 12%, Mo: 1%, with the balance being Fe and unavoidable impurities.

[0046] Specifically, the combination of high carbon and high chromium ensures the formation of a large amount of high-hardness chromium carbides after solidification and heat treatment. These hard phases form the first barrier against abrasive wear. The addition of molybdenum significantly improves the alloy's hardenability, enabling the thicker cross-section of the triangular pyramid support 200 to achieve a uniform, high-hardness martensitic structure, even under oil quenching conditions, thus preventing a soft core. Simultaneously, molybdenum refines the microstructure, improves the uniformity of carbide distribution, and enhances high-temperature strength. This composition allows the triangular pyramid support 200 to maintain the necessary toughness to resist impact spalling while possessing extremely high surface hardness (up to HRC60 or higher), ensuring a long service life for the medium.

[0047] The triangular pyramid core 100 and the triangular pyramid support 200 are fixedly connected by a metallurgical bonding method, and a mutual melting and diffusion layer is formed at the connection interface.

[0048] Specifically, using metallurgical bonding can reduce the risk of interface separation, allowing loads to be transferred smoothly and efficiently through the interface, thus avoiding overall structural damage caused by interface failure.

[0049] Example 2

[0050] This embodiment discloses the preparation process of the low-chromium polyhedral abrasive media of Example 1, including the following steps: S1. Use drafting software to draw model diagrams of the triangular pyramid core 100 and the triangular pyramid support 200. Based on the model diagrams, make individual molds of the triangular pyramid support 200 and overall molds of the triangular pyramid core 100 and the triangular pyramid support 200 after they are combined. In this embodiment, SolidWords is used to draw the model diagram of the triangular pyramid core 100 and the triangular pyramid support 200. First, the triangular pyramid support 200 is drawn, and the diameter of the four spheres 201 of the triangular pyramid support 200 is set to 7mm. The four spheres 201 are distributed in a pyramidal vertex pattern, and the distance between the centers of two adjacent spheres 201 is 60mm. Between two adjacent spheres 201, a prism 202 with a diameter of 3.5mm is drawn. The prism is an outwardly expanding arc with a diameter of 100mm, resulting in... The model drawing of the triangular pyramid support 200 is then drawn, and the triangular pyramid core 100 is drawn inside the triangular pyramid support 200: a hemisphere is taken at the inner center of each sphere 201 as a hemispherical groove, and a semi-cylinder is taken at the inner center of each pyramid 202 as a semi-cylindrical concave rail. Then, the edge trajectory of the hemispherical groove and the semi-cylindrical concave rail is connected to form the triangular pyramid core 100; then, the individual mold of the triangular pyramid support 200 and the overall mold after the triangular pyramid core 100 and the triangular pyramid support 200 are drawn.

[0051] S2. Add the ferrochrome alloy raw material of the triangular pyramid support 200 to the furnace according to the mass percentage and melt it into high chromium iron molten metal. Then pour it into the single mold, cool it and demold it to obtain the triangular pyramid support 200. In this embodiment, C: 2.5%, Si: 0.5%, Mn: 1%, Cr: 12%, Mo: 1%, with the balance being Fe and unavoidable impurities, are added to a furnace and smelted into high-chromium molten iron according to the mass percentage. The molten iron is then poured into a single mold, cooled, and demolded to obtain a triangular pyramid support 200. S3. Add the ferrochrome alloy raw material of the triangular pyramid core 100 to the furnace according to the mass percentage and melt it into low-chromium molten iron. Place the triangular pyramid support 200 into the integral mold and fit it in. Then pour the low-chromium molten iron into the integral mold, and demold it after cooling to obtain the medium blank. In this embodiment, according to the following mass percentages: C: 1%, Si: 0.5%, Mn: 0.8%, Cr: 0.8%, with the balance being Fe and unavoidable impurities, the mixture is added to a furnace and smelted into low-chromium molten iron, which is then poured into a single mold, cooled, and demolded to obtain a triangular pyramid support 200. S4. The media blank is quenched and tempered sequentially to obtain a low-chromium polyhedral grinding media. In this embodiment, the media blank is placed in a heating furnace, heated to 950-1050℃, held for more than 1 hour, and then slowly air-cooled to room temperature; the quenched media blank is placed in a heating furnace, heated to 200-350℃, held for 2-4 hours, and then air-cooled to obtain a low-chromium polyhedral grinding media.

[0052] The manufacturing process of this invention breaks down the production of complex composite components into two relatively simple casting steps, offering significant industrial advantages. First, step-by-step casting allows for separate optimization of the melting and casting process parameters for the high-chromium support and the low-chromium core, ensuring optimal internal quality for each and avoiding defects such as hot cracking and shrinkage porosity caused by significant differences in shrinkage rate and thermal conductivity between the two alloys during integral casting. Second, the strategy of prefabricating the triangular pyramid support and then integrally molding the composite structure utilizes the second pour of low-chromium molten iron to simultaneously achieve two functions: forming the core body and completing the metallurgical bond with the support. This method features a short process flow, conventional equipment requirements, strong process controllability, and high yield, making it highly suitable for large-scale, low-cost, high-quality, and stable production.

[0053] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A low-chromium polyhedral abrasive media, characterized in that, The device includes a triangular pyramid core (100) and a triangular pyramid support (200) fixed to the outside of the triangular pyramid core (100). The triangular pyramid support (200) includes four spheres (201) and six prisms (202) respectively connected between two adjacent spheres (201). The four spheres (201) are fixed at the four vertices of the triangular pyramid core (100), and the six prisms (202) are fixed on the six edges of the triangular pyramid core (100). The triangular pyramid core (100) and the triangular pyramid support (200) are both made of ferrochrome alloy, wherein the chromium content in the triangular pyramid core (100) is 0.5-1.0%, and the chromium content in the triangular pyramid support (200) is 11-15%.

2. The low-chromium polyhedral abrasive media according to claim 1, characterized in that, The triangular pyramid core (100) is shaped like a regular triangular pyramid, with all four triangular faces being arc surfaces and all six edges being arc edges.

3. The low-chromium polyhedral abrasive media according to claim 1, characterized in that, The four vertices of the triangular pyramid core (100) are all recessed hemispherical grooves, and the six edges are all recessed semi-cylindrical grooves; the four spheres (201) are respectively embedded in the hemispherical grooves, and the six prisms (202) are respectively embedded in the semi-cylindrical grooves.

4. The low-chromium polyhedral abrasive media according to claim 3, characterized in that, In S1, the diameter ratio of the sphere (201) to the prism (202) in the triangular pyramid support (200) is 2:

1.

5. The low-chromium polyhedral abrasive media according to claim 1, characterized in that, The raw materials of the ferrochrome alloy of the triangular pyramid core (100) include, by mass percentage: C: 0.8-1.2%, Si: 0.3-0.8%, Mn: 0.5-1.0%, Cr: 0.5-1.0%, with the balance being Fe and unavoidable impurities.

6. The low-chromium polyhedral abrasive media according to claim 1, characterized in that, The raw materials of the ferrochrome alloy of the triangular pyramid support (200) include, by mass percentage: C: 2.0-3.0%, Si: ≤1.0%, Mn: 0.5-1.5%, Cr: 11-15%, Mo: 0.5-1.5%, with the balance being Fe and unavoidable impurities.

7. The low-chromium polyhedral abrasive media according to claim 1, characterized in that, The triangular pyramid core (100) and the triangular pyramid support (200) are fixedly connected by a metallurgical bonding method, and a mutual melting and diffusion layer is formed at the connection interface.

8. A preparation process for preparing the low-chromium polyhedral abrasive media as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Use drawing software to draw the model diagram of the triangular pyramid core (100) and the triangular pyramid support (200). Based on the model diagram, make the individual mold of the triangular pyramid support (200) and the overall mold after the triangular pyramid core (100) and the triangular pyramid support (200) are combined. S2. The ferrochrome alloy raw material of the triangular pyramid support (200) is added to the furnace according to the mass percentage and melted into high chromium iron. Then it is poured into the single mold, cooled and demolded to obtain the triangular pyramid support (200). S3. Add the ferrochrome alloy raw material of the triangular pyramid core (100) to the furnace according to the mass percentage and melt it into low-chromium molten iron. Place the triangular pyramid support (200) in the integral mold and fit it in. Then pour the low-chromium molten iron into the integral mold, and demold it after cooling to obtain the medium blank. S4. The media blank is quenched and tempered in sequence to obtain a low-chromium polyhedral grinding media.

9. The preparation process according to claim 8, characterized in that, In S4, the quenching process is as follows: the medium blank is placed in a heating furnace, heated to 950-1050℃, held for more than 1 hour, and then air-cooled to room temperature.

10. The preparation process according to claim 8, characterized in that, In S4, the tempering process is as follows: the quenched medium blank is placed in a heating furnace, heated to 200-350℃, held for 2-4 hours, and then air-cooled.

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