Material modifier for ultrahigh-chromium high-carbon cast iron, ultrahigh-chromium high-carbon cast iron and smelting method of ultrahigh-chromium high-carbon cast iron

Abstract

The invention relates to the technical field of metallurgy, and particularly discloses a material modifier for ultrahigh-chromium high-carbon cast iron, the ultrahigh-chromium high-carbon cast iron and a smelting method of the ultrahigh-chromium high-carbon cast iron. The material modifier for the ultrahigh-chromium high-carbon cast iron is alloy metal powder and comprises the following raw materials in parts by weight: 6-8 parts of ferroniobium powder, 0.2-0.4 part of chromium nitride, 0.2-0.4 part of tungsten nitride, 0.15-0.25 part of vanadium nitride, 0.3-0.5 part of molybdenum nitride, 0.5-1.5 parts of chromium carbide and 3-5 parts of silicon carbide. The impact toughness and Rockwell hardness of the ultrahigh-chromium and high-carbon cast iron using the material modifier for the ultrahigh-chromium and high-carbon cast iron are as high as 4.90 J / cm < 2 > and 68.5 HRC, the toughness and hardness of the ultrahigh-chromium and high-carbon cast iron are improved, the minimum wear rate is 0.30%, and the ultrahigh-chromium and high-carbon cast iron has high wear resistance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metallurgy, in particular to a material modifier for super-high-chromium high-carbon cast iron, super-high-chromium high-carbon cast iron and a smelting method thereof. BACKGROUND

[0002] High-chromium cast iron is the third generation of white cast iron developed after ordinary white cast iron and nickel hard cast iron, and is widely used in the fields of mining, cement, metallurgy, power and the like. Since the hardness of carbide is high, the carbon content of high-chromium cast iron can change the content of carbide, thereby greatly affecting the hardness of high-chromium cast iron. Higher carbon content can increase the content of carbide and improve the wear resistance of high-chromium cast iron, but when the carbon content increases to a certain extent, coarse primary carbide and eutectic groups will appear in the high-chromium cast iron, which can cause relatively poor toughness. The high-chromium cast iron with relatively low toughness is prone to cracking under high impact or large particle impact, which reduces the impact resistance of the high-chromium cast iron workpiece, shortens the service life, increases the consumption of manpower and material resources, and restricts the overall benefit of the enterprise. Therefore, it has become an urgent need for the development of the industry to develop high-hardness high-toughness wear-resistant high-chromium cast iron.

[0003] In the related art, titanium and silicon elements are used to make cast iron modifiers to improve the morphology of the structure and carbide, realize the refinement of the structure and carbide, and thereby improve the hardness of high-chromium cast iron, but only the carbide can be slightly refined, the coarse acicular structure of the primary carbide cannot be changed, the toughness is poor, and it is still difficult to balance the hardness and toughness of high-chromium cast iron. SUMMARY

[0004] In order to improve the hardness and toughness of high-chromium cast iron, the application provides a material modifier for super-high-chromium high-carbon cast iron, super-high-chromium high-carbon cast iron and a smelting method thereof.

[0005] In the first aspect, the application provides a material modifier for super-high-chromium high-carbon cast iron, which adopts the following technical scheme: a material modifier for super-high-chromium high-carbon cast iron, the material modifier for super-high-chromium high-carbon cast iron is an alloy metal powder, which comprises the following raw materials in parts by weight: 6-8 parts of niobium iron powder, 0.2-0.4 parts of chromium nitride, 0.2-0.4 parts of tungsten nitride, 0.15-0.25 parts of vanadium nitride, 0.3-0.5 parts of molybdenum nitride, 0.5-1.5 parts of chromium carbide, and 3-5 parts of silicon carbide.

[0006] By adopting the technical scheme, the niobium-iron powder will combine with carbon and nitrogen preferentially when the metal solidifies, forming fine niobium carbide as a uniformly distributed heterogeneous core, increasing the nucleation rate during solidification, preventing the primary carbide grains from growing excessively, refining the eutectic structure, and improving the hardness and toughness of the cast iron. In addition, the niobium-iron powder hinders dislocation movement during subsequent heat treatment, producing a "dispersion strengthening" effect, reducing the size of the eutectic structure and increasing the number of eutectic structures, and the niobium-rich carbide can further fix impurities such as sulfur, thereby improving the toughness and thermal shock resistance of the cast iron.

[0007] Chromium nitride has a high melting point and is not easily dissolved in molten iron, which can be used as a nucleation core for primary austenite or carbide, refining the grains and carbides, and making the primary M7C3 carbide in the form of fine short rods, avoiding the distribution of coarse carbide in the form of thick strips, making the distribution of the refined carbide more uniform, and the chromium nitride itself has high hardness, which can improve the hardness and toughness of the cast iron. In addition, nitrogen can promote the uniform distribution of chromium in the matrix, reducing the segregation of chromium.

[0008] Tungsten nitride has good stability in molten iron and is a strong nucleating agent that can significantly refine austenite grains and carbides. The dissolved tungsten in the matrix can improve the hardness of the austenite or martensite matrix through solid solution strengthening. Undissolved WN particles can serve as hard points to improve the material's resistance to abrasive wear.

[0009] Vanadium nitride significantly refines the grains and reduces the formation of coarse carbides as a nucleation core. Vanadium has strong affinity with carbon and nitrogen, and the particles formed can be adsorbed on the surface of the carbide, preventing the carbide from growing continuously during solidification, making the carbide finer and more dispersed, and smoother without sharp edges. The refined structure can reduce stress concentration while ensuring high hardness, reducing the brittleness of the cast iron, and improving the impact toughness.

[0010] Molybdenum nitride can be used as a nucleating agent to refine the structure. After dissolving into the matrix, it can improve the strength and toughness of the matrix through solid solution strengthening and dispersion strengthening, while promoting the fine and uniform distribution of carbides. In addition, molybdenum nitride is a key element for improving the hardenability of high-chromium cast iron, which can reduce the critical quenching cooling rate requirement, making it easier to obtain a martensite matrix in cast iron, reducing the amount of residual austenite, and thus improving the hardness and toughness of the cast iron.

[0011] Chromium carbide is a high-hardness carbide that can act as an additional wear-resistant point, working in conjunction with the M7C3 carbide formed by the cast iron itself to significantly improve wear resistance. Moreover, chromium carbide promotes the formation of fine, smooth, and non-sharp-edged M7C3 carbide in molten iron, avoiding the formation of coarse network-shaped carbide due to insufficient chromium content, thereby improving the hardness and toughness of the cast iron.

[0012] Silicon carbide is a strong deoxidizer. It can combine with oxygen in molten iron to form SiO2 slag, remove gases and inclusions, purify molten iron, and reduce defects such as porosity and inclusions in castings. On the other hand, the fine carbon particles decomposed from silicon carbide in molten iron can serve as nucleation nuclei, refine the size of primary carbides, promote uniform distribution of carbides, and inhibit the formation of coarse carbides.

[0013] Chromium nitride, tungsten nitride, vanadium nitride, molybdenum nitride, and silicon carbide, acting as nucleation sites, can work together to provide more nucleation sites, enabling cast iron to form more crystal nuclei during solidification, thus significantly refining the grains and carbides. When vanadium nitride and silicon carbide are present simultaneously, vanadium nitride can form stable nucleation sites first at high temperatures, while silicon carbide can further supplement nucleation sites in later stages. Their synergistic effect further refines the carbides, exhibiting a certain composite effect.

[0014] Preferably, the weight ratio of vanadium nitride to silicon carbide is 1:(15-30).

[0015] By adopting the above scheme and adjusting the weight ratio of vanadium nitride to silicon carbide, the composite effect of the two can be further improved, which is more conducive to promoting the refinement of carbides and making the carbides evenly distributed, thereby further improving the hardness and toughness of cast iron.

[0016] Preferably, the powder particle size of the ultra-high chromium high-carbon cast iron material modifier is 100-150 mesh.

[0017] By adopting the above scheme, the particle size of the material modifier powder is controlled at 100-150 mesh, avoiding local enrichment, ensuring that the material modifier dissolves quickly and disperses evenly, and fully exerts its effect to improve the hardness and toughness of cast iron.

[0018] Preferably, the silicon carbide is obtained through modification, specifically: S1. Dry silicon carbide at 300-500℃ for 2-3 hours to obtain pretreated silicon carbide; S2. Mix the pretreated silicon carbide with 100-150 mesh chromium powder, purge with argon gas, and ball mill at 300-400 r / min to uniformly coat the silicon carbide with chromium powder, thus obtaining modified silicon carbide.

[0019] By adopting the above scheme, the silicon carbide is first dried to remove the surface-adsorbed moisture, thus avoiding the agglomeration of "liquid bridges" between silicon carbide particles caused by moisture. This promotes the uniform coating of silicon carbide with chromium powder, thereby improving the dispersion uniformity of silicon carbide in molten iron.

[0020] Using chromium powder to coat silicon carbide can improve the dispersibility of silicon carbide in molten iron. Under high-energy ball milling, the chromium powder will undergo plastic deformation, tightly coating the SiC surface, and the chromium powder is not easy to fall off.

[0021] Preferably, the mass ratio of chromium powder to silicon carbide is 1:(2-3).

[0022] By adopting the above scheme and adjusting the mass ratio of chromium powder to silicon carbide, the dispersion uniformity of silicon carbide in molten iron is further improved, thereby enhancing the effect of silicon carbide in refining carbides, ensuring uniform carbide distribution, and improving the hardness and toughness of cast iron.

[0023] Secondly, this application provides an ultra-high chromium high-carbon cast iron using any of the aforementioned material modifiers for ultra-high chromium high-carbon cast iron, specifically achieved through the following technical solution: An ultra-high chromium high-carbon cast iron using an ultra-high chromium high-carbon cast iron material modifier comprises the following elements in weight percentage: C 4.4-4.6%, Si 0.3-0.8%, Mn 2-2.5%, Cr 30-32%, Mo 2.8-3.3%, Ni 0-1.6%, Cu 0.4-1.6%, with the balance being Fe and impurities; The amount of the modifier added to the ultra-high chromium high-carbon cast iron material is 0.8-1% of the carbon equivalent.

[0024] By adopting the above technical solutions, the carbon content of ultra-high chromium high-carbon cast iron is greater than 4.3%, making it a hypereutectic cast iron, which endows the cast iron with high hardness and high wear resistance. Furthermore, with a chromium content of 30-32%, chromium, a strong carbide-forming element, combines with carbon to form high-hardness alloy carbides distributed in the matrix, effectively resisting cutting and extrusion during wear and increasing the hardness of the cast iron. In addition, increased chromium, molybdenum, manganese, and carbon content can form stable alloy carbides, promoting carbide formation and improving the toughness and strength of the cast iron.

[0025] By controlling the amount of material modifier, the negative effects of insufficient or excessive dosage can be avoided while ensuring the modification effect, so as to achieve the optimal balance between material performance, process stability and production cost.

[0026] Thirdly, this application provides a method for smelting any of the above-mentioned ultra-high chromium high-carbon cast iron, which is specifically achieved through the following technical solution: A method for smelting ultra-high chromium high-carbon cast iron includes the following steps: S1. Fill the smelting furnace with pig iron and scrap steel, heat it until a molten pool is formed at the bottom, add preheated ferrochrome and ferromanganese, and after the furnace charge is completely melted, add pure Ni and ferromolybdenum to obtain molten iron. S2. Place the deoxidizer, ferrovanadium, ferrotitanium, and ferroboron in a preheated ladle according to the proportions, pour the molten iron into the ladle, and add the material modifier for ultra-high chromium high-carbon cast iron to the molten iron by pouring. The furnace temperature is 1510-1540℃. When the temperature of the molten iron drops to 1415-1435℃, pour it into a casting. After casting, cover the heat-insulating riser with refractory asbestos for heat preservation. Finally, heat treat to obtain ultra-high chromium high-carbon cast iron castings.

[0027] As a preferred option, when adding the material modifier for ultra-high chromium high-carbon cast iron, in-flow inoculation should be carried out.

[0028] By adopting the above technical solution, when adding the material modifier for ultra-high chromium high-carbon cast iron, in-flow inoculation is carried out. As a preferred method, the heat treatment specifically involves heating the furnace at room temperature to 350°C and holding for 1 hour, heating to 360°C and holding for 1 hour, heating to 850°C and holding for 1 hour, heating to 1050°C and holding for 5 hours, cooling to 950°C and holding for 1 hour, and finally air cooling.

[0029] By adopting the above technical solution, heat treatment using a four-stage heating + five-stage heat preservation + slow cooling heat preservation method can make the temperature of each part of the cast iron more uniform, avoid stress superposition causing deformation or cracking of the cast iron, raise the temperature to 1050℃ and hold for 5 hours to extend the heat preservation time, so that the elements inside the base metal can be fully diffused and homogenized, and secondary carbides can be precipitated. Slow cooling to 950℃ can make the temperature of the cast iron uniform and improve the hardness and toughness of the cast iron.

[0030] During heat treatment, the heating and cooling rates must be strictly controlled to prevent the casting from cracking due to the superposition of structural and structural stresses.

[0031] In summary, this application includes at least one of the following beneficial technical effects: 1. This application utilizes the types and dosages of raw materials in the material modifier, and adds the material modifier for ultra-high chromium high-carbon cast iron during the smelting process to induce in-flow inoculation, thereby achieving an impact toughness and Rockwell hardness of 4.78-4.80 J / cm for ultra-high chromium high-carbon cast iron. 2 With a hardness of 64.5-65.8 HRC and a wear rate of 0.33%, it exhibits high toughness and hardness, thus enhancing the wear resistance of ultra-high chromium high-carbon cast iron.

[0032] 2. This application improves the toughness and hardness of ultra-high chromium high carbon cast iron by controlling the particle size of the material modifier for ultra-high chromium high carbon cast iron, resulting in impact toughness and Rockwell hardness of 4.83 J / cm2 and 66.2 HRC, respectively, and a wear rate of 0.32%.

[0033] 3. This application modifies the silicon carbide in the material modifier and adjusts the mass ratio of chromium powder to silicon carbide to make the impact toughness and Rockwell hardness of ultra-high chromium high carbon cast iron 4.87-4.90 J / cm2 and 68.3-68.5 HRC, respectively, with a wear rate of 0.30%, thereby further improving the toughness and hardness of ultra-high chromium high carbon cast iron and giving it high wear resistance. Attached Figure Description

[0034] Figure 1 Metallographic images of ultra-high chromium high-carbon cast iron without the use of material modifiers Figure 2 Metallographic images of ultra-high chromium high-carbon cast iron using material modifiers Detailed Implementation

[0035] The following detailed description, in conjunction with specific embodiments, further illustrates this application. All the raw materials used in this application are commercially available products and are intended to fully disclose the raw materials used in this application; they should not be construed as limiting the source of the raw materials. Specifically: niobium iron powder, niobium content 50-70%, particle size 200 mesh; chromium nitride, effective substance content 99.9%, particle size 200 mesh; tungsten nitride, effective substance content 99%; vanadium nitride, particle size 200 mesh; molybdenum nitride, molybdenum content 99.5%, particle size 200 mesh; chromium carbide, particle size 200 mesh; silicon carbide, silicon content 99%, particle size 200 mesh; chromium powder, chromium content ≥86%, particle size 200 mesh.

[0036] The following are examples of the preparation of modified silicon carbide: Preparation Example 1 The modified silicon carbide of Example 1 was prepared by the following steps: S1. Dry 1 kg of silicon carbide at 400℃ for 2.5 h to obtain pretreated silicon carbide; S2. Mix 1 kg of pretreated silicon carbide with 1 kg of 130-mesh chromium powder, purge with argon gas, and ball mill at 350 r / min using stainless steel balls at a ball-to-material ratio of 1:10 to ensure that the chromium powder uniformly coats the silicon carbide, thus obtaining modified silicon carbide.

[0037] Preparation Examples 2-5 The modified silicon carbide in Preparation Examples 2-5 uses the same raw materials and preparation method as Preparation Example 1, except for the amount of chromium powder added. The amounts of chromium powder added are 500g, 400g, 333g and 250g, respectively, while the amounts of other raw materials are the same as in Preparation Example 1.

[0038] Example 1 The ultra-high chromium high-carbon cast iron material modifier of Example 1 was prepared through the following steps: The raw materials were mixed in proportion and kept at 300℃ for 4 hours. The mixture was then placed in a vacuum induction medium-frequency electric furnace for melting. After melting, the molten alloy was poured into a pre-prepared metal mold and alloy preforms were poured in. After the molten alloy cooled, alloy preforms were obtained. The alloy preforms were crushed into particles with a particle size of 40mm using a crusher. The crushed particles were then prepared into 130-mesh metal powder using a metal ultrasonic atomization device. Under vacuum conditions, the molten alloy was first melted and then poured into an atomizer to atomize into powder, thus obtaining a material modifier for ultra-high chromium high-carbon cast iron. The specific dosage is shown in Table 1.

[0039] Examples 2-5 The preparation methods and raw material types of the ultra-high chromium high-carbon cast iron material modifiers in Examples 2-5 are exactly the same as those in Example 1, except that the dosage of each raw material is different, as detailed in Table 1.

[0040] Table 2. Dosage of each raw material in the modifier for ultra-high chromium high-carbon cast iron in Examples 1-5 (unit: kg) Example 6 The preparation method of the material modifier for ultra-high chromium high-carbon cast iron in Example 6 is the same as that in Example 3, except that the powder particle size of the material modifier is 130 mesh, and the other steps are the same as those in Example 3.

[0041] Examples 7-11 The preparation methods of the material modifiers for ultra-high chromium high-carbon cast iron in Examples 7-11 are the same as those in Example 6, except that the silicon carbide used is the modified silicon carbide prepared in Examples 1-5, and the other raw materials and dosages are the same as those in Example 6.

[0042] Comparative Example 1 The preparation method of the ultra-high chromium high-carbon cast iron material modifier in Comparative Example 1 is exactly the same as that in Example 1, except that vanadium nitride is replaced with silicon carbide in equal amounts, and the other raw materials and dosages are the same as in Example 1.

[0043] Comparative Example 2 The preparation method of the ultra-high chromium high-carbon cast iron material modifier in Comparative Example 2 is exactly the same as that in Example 1, except that silicon carbide is replaced with vanadium nitride in equal amounts, while the other raw materials and dosages are the same as in Example 1.

[0044] The following are examples of applications of material modifiers for ultra-high chromium high-carbon cast iron. Application Example 1 The specific application method of the modifier for ultra-high chromium high-carbon cast iron is as follows: The obtained ultra-high chromium high-carbon cast iron contains the following elements by weight percentage: C 4.5%, Si 0.5%, Mn 2.3%, Cr 31%, Mo 3.0%, Ni 1.0%, Cu 1.0%, with the balance being Fe and impurities.

[0045] The smelting method for ultra-high chromium high-carbon cast iron includes the following steps: S1. Fill the smelting furnace with pig iron and scrap steel, heat it until a molten pool is formed at the bottom, add preheated ferrochrome and ferromanganese, and after the furnace charge is completely melted, add pure Ni and ferromolybdenum to obtain molten iron. S2. The deoxidizer, ferrovanadium, ferrotitanium, and ferroboron are placed in a preheated ladle in proportion. The amounts of ferrovanadium, ferrotitanium, and ferroboron added are 0.2%, 1.0%, and 0.8% of the molten iron mass, respectively. The molten iron is poured into the ladle, and the ultra-high chromium high-carbon cast iron material modifier prepared in Example 1 is added to the molten iron using a pouring method. The tapping temperature is 1520℃. When the molten iron temperature drops to 1425℃, it is cast into a casting. After casting, refractory asbestos is covered with the heat-insulating riser for insulation. Finally, heat treatment is performed. The process employs a four-stage heating + five-stage heat preservation + slow cooling heat preservation method. Specifically, the furnace is heated from room temperature to 350℃ and held for 1 hour at a heating rate of 80℃ / h, then heated to 360℃ and held for 1 hour at a heating rate of 100℃ / h, then heated to 850℃ and held for 1 hour at a heating rate of 100℃ / h, then heated to 1050℃ and held for 5 hours at a heating rate of 150℃ / h, then cooled to 950℃ and held for 1 hour at a cooling rate of 150℃ / h, and finally air-cooled to obtain ultra-high chromium high-carbon cast iron castings.

[0046] Application Example 2 Application Example 2: Application of material modifier for ultra-high chromium high-carbon cast iron. The difference between the method for ultra-high chromium high-carbon cast iron and Application Example 1 is that when adding the material modifier for ultra-high chromium high-carbon cast iron, in-flow inoculation is carried out. That is, when 50% of the molten iron is poured in, the material modifier is slowly poured into the molten iron stream to fully mix with the molten iron. The remaining steps are the same as in Application Example 1.

[0047] Application Example 3-12 Application Example 3-12: The application of the material modifier for ultra-high chromium high-carbon cast iron differs from Application Example 2 in that the material modifier for ultra-high chromium high-carbon cast iron is the same as that prepared in Example 2-11. The remaining steps are the same as in Application Example 2.

[0048] Application Comparative Example 1-2 The application of the material modifier for ultra-high chromium high-carbon cast iron in Comparative Examples 1-2 differs from that in Application Example 1 in that the material modifier for ultra-high chromium high-carbon cast iron is the same as that prepared in Comparative Examples 1-2. The remaining steps are the same as in Application Example 1.

[0049] Application Comparative Example 3 The difference between Application Example 3 (Ultra-high Chromium High-Carbon Cast Iron) and Application Example 1 is that no material modifier for ultra-high chromium high-carbon cast iron was added; the remaining steps are the same as in Application Example 1.

[0050] Performance testing The performance of ultra-high chromium high-carbon cast iron obtained from different application examples 1-12 and application comparison examples 1-2 was tested using the following testing standards or methods. The test results are shown in Table 2.

[0051] Impact toughness: 20mm×20mm×110mm impact specimens were cut by wire cutting and impact toughness tests were performed on a JB-30A impact testing machine.

[0052] Rockwell hardness: 20mm×20mm×110mm impact specimens were cut by wire cutting and Rockwell hardness was tested on an HR-150A Rockwell hardness tester.

[0053] Wear rate: The wear test was conducted on an MST-120 wear tester. The wear medium was water and refined quartz sand. The quartz sand was 20-40 mesh, approximately HV1100. The weight ratio of water to refined quartz sand was 2:3. The rotation speed was 2880 r / min. The pre-grinding time was 8 hours. The wear rate was then calculated.

[0054] Table 2 Performance test results of different ultra-high chromium high-carbon cast irons The test results in Table 3 show that the ultra-high chromium high-carbon cast iron prepared using the material modifier obtained in this application has an impact toughness and Rockwell hardness as high as 4.90 J / cm. 2 With a hardness of 68.5 HRC, it improves the toughness and hardness of ultra-high chromium high-carbon cast iron, with a wear rate as low as 0.30%, exhibiting high wear resistance.

[0055] Combining the data from Application Examples 1 and 2, it was found that the impact toughness and Rockwell hardness of the ultra-high chromium high-carbon cast iron in Application Example 2 were 4.77 J / cm². 2 The hardness and wear resistance were 64.1 HRC, higher than in Application Example 1, and the wear rate was 0.34%, lower than in Application Example 1. This indicates that adding a material modifier for ultra-high chromium high-carbon cast iron during inoculation improves the toughness and hardness of ultra-high chromium high-carbon cast iron, and also improves its wear resistance.

[0056] Combining the data from the ultra-high chromium high-carbon cast iron in Application Examples 2-6, it was found that the impact toughness and Rockwell hardness of the ultra-high chromium high-carbon cast iron in Application Examples 3-5 were 4.78-4.80 J / cm². 2The HRC value was 64.5-65.8, higher than that of Application Examples 2 and 6, and the wear rate was 0.33%, lower than that of Application Examples 2 and 6. This indicates that a weight ratio of vanadium nitride to silicon carbide in the material modifier of 1:(15-30) is more suitable, which can further improve the toughness and hardness of ultra-high chromium high-carbon cast iron, and improve its wear resistance.

[0057] Combining the data from Application Examples 4 and 7, it was found that the impact toughness and Rockwell hardness of the ultra-high chromium high-carbon cast iron in Application Example 7 were 4.83 J / cm². 2 The HRC value was 66.2, higher than that of Application Example 4, and the wear rate was 0.32%, lower than that of Application Example 4. This indicates that a particle size of 130 mesh is more suitable for the material modifier used in ultra-high chromium high-carbon cast iron, which improves the toughness and hardness of ultra-high chromium high-carbon cast iron and enhances its wear resistance.

[0058] Combining the data from the ultra-high chromium high-carbon cast iron in Application Examples 8-12, it was found that the impact toughness and Rockwell hardness of the ultra-high chromium high-carbon cast iron in Application Examples 9-11 were 4.87-4.90 J / cm². 2 The hardness and wear resistance of ultra-high chromium high-carbon cast iron were 68.3-68.5 HRC, higher than those of Application Example 8 and Example 12, and the wear rate was 0.30%, lower than those of Application Example 8 and Example 12. This indicates that when modifying silicon carbide in the material modifier, controlling the mass ratio of chromium powder to silicon carbide to 1:(2-3) can further improve the toughness and hardness of ultra-high chromium high-carbon cast iron, and improve its wear resistance.

[0059] Furthermore, based on the data of various indicators of ultra-high chromium high-carbon cast iron from Comparative Examples 1-3 and Application Example 1, it was found that applying the material modifier obtained in this application to the smelting of ultra-high chromium high-carbon cast iron, as well as simultaneously adding vanadium nitride and silicon carbide to the material modifier, can improve the toughness and hardness of ultra-high chromium high-carbon cast iron to varying degrees, and also improve its wear resistance.

[0060] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A material modifier for ultra-high chromium high-carbon cast iron, characterized in that, The material modifier for ultra-high chromium high-carbon cast iron is an alloy metal powder, which includes the following raw materials in parts by weight: 6-8 parts of niobium iron powder, 0.2-0.4 parts of chromium nitride, 0.2-0.4 parts of tungsten nitride, 0.15-0.25 parts of vanadium nitride, 0.3-0.5 parts of molybdenum nitride, 0.5-1.5 parts of chromium carbide, and 3-5 parts of silicon carbide.

2. The material modifier for ultra-high chromium high carbon cast iron according to claim 1, characterized by, The weight ratio of vanadium nitride to silicon carbide is 1:(15-30).

3. The material modifier for ultra-high chromium high carbon cast iron according to claim 1, characterized by, The powder particle size of the material modifier for ultra-high chromium high-carbon cast iron is 100-150 mesh.

4. The material modifier for ultra-high chromium high carbon cast iron according to claim 1, characterized by, The silicon carbide is obtained through modification, specifically: S1. Dry silicon carbide at 300-500℃ for 2-3 hours to obtain pretreated silicon carbide; S2. Mix the pretreated silicon carbide with 100-150 mesh chromium powder, purge with argon gas, and ball mill at 300-400 r / min to uniformly coat the silicon carbide with chromium powder, thus obtaining modified silicon carbide.

5. The material modifier for ultra-high chromium high carbon cast iron according to claim 4, characterized by The mass ratio of chromium powder to silicon carbide is 1:(2-3).

6. A super-chromium high-carbon cast iron using the material modifier for super-chromium high-carbon cast iron according to any one of claims 1 to 5, characterized by, The ultra-high chromium high-carbon cast iron contains the following elements by weight percentage: C 4.4-4.6%, Si 0.3-0.8%, Mn 2-2.5%, Cr 30-32%, Mo 2.8-3.3%, Ni 0-1.6%, Cu 0.4-1.6%, with the balance being Fe and impurities; In the process of smelting the ultra-high chromium high-carbon cast iron, a material modifier for ultra-high chromium high-carbon cast iron is added; the amount of the material modifier added is 0.8-1% of the carbon equivalent.

7. A method of smelting the ultra-high chromium high carbon cast iron as claimed in any one of claims 6, characterized in that, The following steps are included: S1. Fill the smelting furnace with pig iron and scrap steel, heat it until a molten pool is formed at the bottom, add preheated ferrochrome and ferromanganese, and after the furnace charge is completely melted, add pure Ni and ferromolybdenum to obtain molten iron. S2. Place the deoxidizer, ferrovanadium, ferrotitanium, and ferroboron in a preheated ladle according to the proportions. Pour the molten iron into the ladle and add the material modifier for ultra-high chromium high-carbon cast iron to the molten iron by pouring. The tapping temperature is 1510-1540℃. When the temperature of the molten iron drops to 1415-1435℃, pour it into a casting. After casting, cover the heat-insulating riser with refractory asbestos for heat preservation. Finally, perform heat treatment to obtain ultra-high chromium high-carbon cast iron castings.

8. The melting method of ultra-high chromium high carbon cast iron according to claim 7, characterized in that, When adding the modifier for ultra-high chromium high-carbon cast iron, in-flow inoculation is carried out.

9. The melting method of ultra-high chromium high carbon cast iron according to claim 7, characterized in that, The heat treatment specifically involves heating the furnace from room temperature to 350°C and holding for 1 hour, heating to 360°C and holding for 1 hour, heating to 850°C and holding for 1 hour, heating to 1050°C and holding for 5 hours, cooling to 950°C and holding for 1 hour, and finally air cooling.

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