A nanometer precipitated phase dispersion strengthening liner plate casting and a preparation method thereof

Abstract

A nano precipitate dispersion strengthened liner cast and a preparation method thereof. The nano precipitate dispersion strengthened liner cast comprises the following components in mass percentage: C 0.1-1%, Si 0.3-2%, Mn 0.3-2%, Cr 0.5-3%, Mo 0.1-2%, Ni 0.1-1%, Ti 0.01-0.5%, V 0.01-0.5%, Nb 0.01-0.5%, N 0-0.05%, La+Ce 0-0.1%, P 0-0.1%, S 0-0.1%, and the balance of Fe and inevitable impurities; the nano precipitate comprises MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitate. In the preparation, the cast steel with the same components as the dispersion strengthened liner cast is subjected to sectional austenitizing quenching and tempering treatment in sequence, and the holding time ratio in the sectional austenitizing process is between 10:1 and 1:1. The nano precipitate dispersion strengthened liner cast has high strength and hardness, good impact toughness and excellent impact and abrasive wear resistance, and does not need additional treatment process, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of semi-autogenous mill liner technology, and more particularly to a nano-precipitated phase dispersion reinforced liner casting and its preparation method. Background Technology

[0002] Fracture, corrosion, and wear are three common forms of material failure. Fracture and corrosion often lead to catastrophic damage to metal workpieces, while wear, although different from the former two and not causing catastrophic damage, can still result in significant economic losses and serious resource waste. With the development of science and technology, the requirements for material performance are becoming increasingly stringent. Wear has become a major factor restricting material use, especially under harsh operating conditions such as mining, where materials not only need high strength and toughness but also require high wear resistance. Therefore, increasing the development of economical and high-performance wear-resistant steels and delving into their strengthening and toughening mechanisms can greatly promote economic and social development.

[0003] Traditional wear-resistant liners are characterized by rapid wear, easy deformation, and short service life, leading to frequent maintenance, unstable operation, and increased production costs. In my country, the liner consumption per ton of ore processed is 0.25 kg / t, while in the United States it is 0.05 kg / t. In large-scale concentrators processing 100,000 tons of ore per day, with iron ore ball mills exceeding 9 meters in diameter, the typical service life of liners is less than 3 months. Maintenance and replacement incur significant additional production costs. For a large ball mill processing 50 million tons of ore annually, downtime costs approximately $300,000 per hour. The average downtime due to replacing wear-resistant liners is around 20 hours, with each downtime resulting in a loss of $6 million. Therefore, improving liner performance and extending service life has significant economic and social value.

[0004] There are many ways to strengthen materials, and introducing nano-carbides is an important approach to improving the mechanical properties of steel. Nano-carbides not only effectively hinder dislocation movement during the deformation process of steel, but also play a role in dispersion strengthening, significantly improving the material's strength and impact toughness. For wear-resistant materials, hard nano-carbides can strengthen the matrix and improve its toughness, reducing wear during use and significantly enhancing the material's wear resistance.

[0005] CN113913589A discloses a high wear-resistant alloy steel forging and its preparation method. The alloy forging, through composition design, hot forging deformation, and subsequent heat treatment processes, produces a large number of dispersed multi-scale (Ti,Mo)C particles and fine Béma multiphase structures in the alloyed carbon steel microstructure. The large-sized micron-sized (Ti,Mo)C particles can effectively resist the micro-cutting action of abrasive grains, while the small-sized submicron-sized (Ti,Mo)C particles and fine Béma structures can enhance the yield strength of the matrix, thereby improving the matrix's resistance to deformation, strengthening the support effect on the large-sized (Ti,Mo)C particles, and improving the wear resistance of the material.

[0006] CN108570625A discloses a special liner steel for autogenous and semi-autogenous grinding mills. Its chemical composition (%) is: C = 0.4–1.1, Si = 0.3–1.2, Mn = 12–19, S < 0.03, P < 0.04, Cr = 12–19, Mo = 0.6–1.5, V = 1.5–2.3, Nb < 0.05, with the remainder being Fe. The alloy employs austenitic supersaturated solid solution strengthening technology and second-phase particle dispersion strengthening technology. Carbides are added to the austenite to obtain a dense and uniform microstructure, thereby achieving high hardness, high yield point, and toughness, improving the initial hardness and wear resistance of the liner. During use, the energy generated by the collision of grinding balls and ore with the liner induces a martensitic phase transformation on the liner surface, further improving the liner's hardness and wear resistance, and extending its service life.

[0007] In traditional industrial production, there are two main methods for introducing nano-precipitates. One method involves adding pre-existing nanoparticles to molten steel during the smelting process, ensuring thorough dispersion before casting and subsequent processing. The other method involves forging / rolling the resulting ingot / billet and then heat-treating it to generate nano-precipitates in the steel. However, both methods have certain drawbacks. For example, the nano-precipitates produced by the first method tend to aggregate in the billet, resulting in uneven distribution, and the cost of producing nanoparticles is high, requiring sophisticated processing techniques when adding them to the molten steel. The second method requires forging / rolling the ingot / billet, leading to higher production costs, and for complex-shaped workpieces, subsequent machining costs are even higher or machining becomes impossible. Summary of the Invention

[0008] Based on the shortcomings of the existing technology, the first objective of this invention is to provide a nano-precipitated phase dispersion reinforced liner casting with high hardness, good impact toughness and excellent wear resistance.

[0009] A second objective of this invention is to provide a method for preparing the nano-precipitated phase dispersion reinforced liner casting.

[0010] A nano-precipitated phase dispersion reinforced liner casting comprises the following mass percentage composition: C 0.1-1%, Si 0.3-2%, Mn 0.3-2%, Cr 0.5-3%, Mo 0.1-2%, Ni 0.1-1%, Ti 0.01-0.5%, V 0.01-0.5%, Nb 0.01-0.5%, N 0-0.05%, La+Ce 0-0.1%, P 0-0.1%, S 0-0.1%, with the balance being Fe and unavoidable impurities.

[0011] Preferably, the nano-precipitated phase includes MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitates, with a volume ratio of 4-6:1-3:0.5-1.5:0.5-1.5:0.8-1.2; more preferably 4.5-5.5:1.5-2.5:0.8-1.2:0.8-1.2:0.9-1.1; and even more preferably 5:2:1:1:1.

[0012] In a further preferred embodiment, the nanoprecipitated phase is spherical or ellipsoidal with a particle size of 10-500 nm, more preferably 50-200 nm.

[0013] Preferably, the composition comprises the following components in the indicated mass percentages: C 0.2–0.6%, Si 0.5–1%, Mn 0.5–1.2%, Cr 1–2%, Mo 0.3–1%, Ni 0.2–0.6%, Ti 0.03–0.1%, V 0.05–0.2%, Nb 0.02–0.07%, N 0–0.02%, La+Ce 0.01–0.06%, P 0–0.02%, S 0–0.02%, with the balance being Fe and unavoidable impurities.

[0014] Another aspect of the present invention discloses a method for preparing a nano-precipitated phase dispersion reinforced liner casting, comprising the following steps:

[0015] (1) Smelting and casting: Smelting is carried out in a medium-frequency induction furnace. First, scrap steel, ferromolybdenum, ferroniobium and nickel wire are added to the magnesium sand crucible in sequence and heated to melt. CaO-CaF2 is added to form slag and the slag is removed. The temperature is raised to 1520-1600℃ for pre-deoxidation and final deoxidation. Then ferromanganese, ferrosilicon, ferrochrome and ferrovanadium are added. After holding for 2-20 minutes, the power of the medium-frequency induction furnace is adjusted to lower the temperature to between 1420-1520℃. Then the molten steel is poured into the sand mold and covered with heating agent and heat-insulating bricks. After cooling, the cast product is obtained.

[0016] (2) Quenching treatment: The cast product obtained in step (1) is heated to 600-800℃ and held for 0.1-12h, then heated to 800-1000℃ and held for 0.1-12h, and then oil cooled to room temperature;

[0017] (3) Tempering treatment: The quenched product is heated to 150-600℃, held for 0.1-24h and then air-cooled to room temperature to obtain the nano-precipitated phase dispersion reinforced liner casting.

[0018] Preferably, in step (1), the sand mold is made of quartz sand, which includes 400 mesh quartz sand and 80 mesh quartz sand, and the volume ratio of 400 mesh quartz sand to 80 mesh quartz sand is 1:7 to 1:1.

[0019] Preferably, in step (2) of the present invention, the ratio of the heat preservation time between 600 and 800°C to the heat preservation time between 800 and 1000°C is 10:1 to 1:1, preferably 5:1 to 8:1.

[0020] Preferably, the melting and holding temperature in step 1) is 1540-1580℃, and the casting temperature is 1440-1500℃.

[0021] Preferably, in step 2), the first insulation temperature is 650-750℃, and the second insulation temperature is 820-920℃.

[0022] Beneficial effects of the present invention

[0023] Compared with existing technologies, this invention promotes the precipitation of nano-precipitates in the liner casting by segmented heat treatment during the austenitization process of quenching heat treatment without adding additional production steps. The disclosed nano-precipitate dispersion-reinforced liner casting has high strength and hardness, good impact toughness, and excellent resistance to impact abrasive wear. Specifically, the room temperature tensile strength is greater than 2000 MPa, the impact toughness is greater than 200 J, and the hardness is greater than 52 HRC. More preferably, the room temperature tensile strength of the liner casting is greater than 2500 MPa, the impact toughness is greater than 230 J, and the hardness is greater than 56 HRC, which is suitable for industrial production. This greatly extends the service life of the liner of large semi-autogenous mills, reduces the waste of resources and energy, and helps to reduce carbon emissions. Attached Figure Description

[0024] Figure 1 Distribution diagram of nano-precipitates in nano-precipitated phase dispersion reinforced liner casting;

[0025] Figure 2 The elemental distribution of C in the nano-precipitated phase of the nano-precipitated phase in the nano-precipitated phase dispersion reinforced liner casting;

[0026] Figure 3The elemental distribution of Ti in the nano-precipitated phase of the nano-precipitated phase in the nano-precipitated phase dispersion reinforced liner casting;

[0027] Figure 4 The nitrogen element distribution diagram of the nano-precipitated phase in the nano-precipitated phase dispersion reinforced liner casting;

[0028] Figure 5 The Nb elemental distribution diagram of the nano-precipitated phase in the nano-precipitated phase dispersion reinforced liner casting;

[0029] Figure 6 Mo elemental distribution diagram of nano-precipitates in nano-precipitated phase dispersion reinforced liner casting;

[0030] Figure 7 The Cr elemental distribution diagram of the nano-precipitated phase in the nano-precipitated phase dispersion reinforced liner casting;

[0031] Figure 8 V element distribution diagram of nano-precipitates in nano-precipitated phase dispersion reinforced liner casting;

[0032] Figure 9 The graph shows the relationship between the percentage of weight loss due to wear and the wear time for different samples under an impact energy of 2.5 J. Detailed Implementation

[0033] The technical solutions of the present invention will be described by way of example below with reference to the embodiments thereof.

[0034] Example 1

[0035] The nano-precipitated phase dispersion reinforced liner casting comprises, by mass percentage, the following components: C: 0.3%, Si: 0.6%, Mn: 1.2%, Cr: 1%, Mo: 0.2%, V: 0.09%, Nb: 0.07%, Ni: 0.70%, La+Ce: 0.06%, P: 0.009%, S: 0.008%, and the balance Fe and unavoidable impurities.

[0036] The preparation method of this nano-precipitated phase dispersion reinforced liner casting material includes the following steps:

[0037] (1) Smelting and casting: Smelting is carried out using a medium-frequency induction furnace. First, scrap steel, ferromolybdenum, ferroniobium and nickel wire are added to a magnesia crucible in sequence and heated to melt. CaO-CaF2 (accounting for 1.5% of the total mass of scrap steel, ferromolybdenum, ferroniobium and ferroniobium) is added to form slag. After slag removal, the temperature is raised to 1560℃, and 20g of aluminum is added for pre-deoxidation and final deoxidation. Then ferromanganese, ferrosilicon, ferrochrome and ferrovanadium are added. After holding at the temperature for 20min, the power of the medium-frequency induction furnace is adjusted. After the temperature drops to 1470℃, the molten steel is poured into a sand mold. A heating agent and insulating bricks are covered on top. After cooling, the as-cast product is obtained.

[0038] (2) Quenching treatment: The prepared cast product is heated to 710℃ and held for 0.5h, then heated to 920℃ and held for 0.5h, and then oil cooled to room temperature.

[0039] (3) Tempering treatment: The quenched product is heated to 550℃ and held for 6 hours before being air-cooled to room temperature to obtain the nano-precipitated phase dispersion reinforced liner casting. The nano-precipitated phase is mainly composed of C, N, Ti, Mo, Cr and V elements, mainly MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitates, with a size between 20-300nm and a precipitate volume ratio of 5:2:1:1:1.

[0040] The performance of the nano-precipitated phase dispersion reinforced liner casting prepared in this embodiment was tested, and the distribution and elemental composition of the nano-precipitated phase were analyzed. The results are shown in Table 1.

[0041] Table 1. Performance of the nano-precipitated phase dispersion reinforced liner casting prepared in Example 1

[0042]

[0043] As shown in Table 1 above, the nano-precipitated phase dispersion reinforced liner casting of the present invention has excellent impact energy, hardness and tensile strength. When its impact abrasive wear performance was tested, the abrasive used was quartz sand with a particle size between 20-40 mesh. The impact energy was 2.5J, the impact time was 10h, and the weight loss percentage of impact abrasive wear was 0.0162%.

[0044] Example 2

[0045] The chemical composition and weight percentage of the nano-precipitated phase dispersion reinforced liner casting material are as follows: C: 0.6%, Si: 0.8%, Mn: 1.4%, Cr: 1.1%, Mo: 0.8%, V: 0.2%, Nb: 0.05%, Ni: 0.50%, La+Ce: 0.06%, P: 0.009%, S: 0.008%, and the balance being Fe and unavoidable impurities.

[0046] The preparation method of this nano-precipitated phase dispersion reinforced liner casting material includes the following steps:

[0047] (1) Smelting and casting: Smelting is carried out using a medium-frequency induction furnace. First, refractory alloys such as scrap steel, ferromolybdenum, ferroniobium and nickel wire are added to a magnesia crucible in sequence and heated to melt. CaO-CaF2 (accounting for 1.5% of the total mass of scrap steel, ferromolybdenum, ferroniobium and ferronickel) is added to form slag. After slag removal, the temperature is raised to 1540℃, and 15g of aluminum is added for pre-deoxidation and final deoxidation. Then, alloy materials such as ferromanganese, ferrosilicon, ferrochrome and ferrovanadium are added. After holding at the temperature for 15 minutes, the power of the medium-frequency induction furnace is adjusted. After the temperature drops to 1460℃, the molten steel is poured into a sand mold. A heating agent and insulating bricks are then covered on top. After cooling, the cast product is obtained.

[0048] (2) Quenching treatment: The prepared cast product is heated to 750°C and held for 1 hour, then heated to 860°C and held for 2 hours, and then oil cooled to room temperature.

[0049] (3) Tempering treatment: The quenched product is heated to 300℃, kept at that temperature for 4 hours, and then air-cooled to room temperature to obtain the nano-precipitated phase dispersion reinforced liner casting.

[0050] The nano-precipitated phase dispersion reinforced liner casting prepared in this embodiment was analyzed by scanning electron microscopy and electron probe microanalysis, and the results are as follows: Figures 1 to 8 As shown in the figure, the microstructure obtained after the above treatment is lath martensite. At the same time, a large number of MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitates rich in C, N, Ti, Mo, Cr and V elements are dispersed in the matrix. The size of the precipitates is between 10-500 nm, and the volume ratio of the precipitates is 5:2:1:1:1. The performance of the nano-precipitate dispersion reinforced liner casting prepared in this example was tested, and the results are shown in Table 2 below.

[0051] Table 2. Performance of the nano-precipitated phase dispersion-reinforced liner casting prepared in Example 2

[0052]

[0053] As shown in Table 2 above, the nano-precipitated phase dispersion reinforced liner casting of the present invention has excellent impact energy, hardness and tensile strength. When the impact abrasive wear performance test was carried out, the abrasive used was quartz sand with a particle size between 20-40 mesh. The impact energy was 2.5J, the impact time was 10h, and the weight loss percentage of impact abrasive wear was 0.0154%.

[0054] Comparative Example 1

[0055] The alloy's mass percentage composition is as follows: C 0.80%, Si 0.5%, Mn 0.4%, Ni 0.7%, Cr 1.9%, Mo 0.45%, Nb 0.02%, V 0.15%, Re 0.03%, S 0.012%, P 0.013%, with the balance being Fe and unavoidable impurities. Its preparation includes the following steps:

[0056] (1) Smelting: The alloy blocks are added to the medium frequency furnace in sequence, and the composition of the molten steel is adjusted to the expected composition. When heated to 1565℃, aluminum wire is fed for deoxidation pretreatment. When heated to 1625℃, aluminum wire is fed for final deoxidation. When the temperature is 1600℃, the molten steel is taken out of the furnace. When it is taken out of the furnace, 0.3% of rare earth alloy and silicon-calcium alloy by mass of the molten steel is added for inoculation modification treatment. The ladle refining technology is used to make the inclusions float to obtain pure molten steel. The molten steel is cast into shape to obtain the liner casting.

[0057] (2) Heat treatment

[0058] Normalizing treatment: After preheating the furnace to 275°C, place the liner casting obtained in step (1) into the furnace, raise the temperature to 650°C at 70°C / h, hold for 2 hours, and then raise the temperature to 930°C at 40°C / h and hold for 6 hours. Then remove the liner from the furnace and air cool to 200-250°C.

[0059] Tempering treatment: After preheating the furnace to 275°C, place the normalized liner in the furnace and raise the temperature to 350°C at 40°C / h. Hold for 2 hours and then raise the temperature to 620°C at 40°C / h and hold for 10 hours. After that, remove the liner from the furnace and allow it to cool to room temperature to obtain the liner for a large semi-autogenous mill.

[0060] The prepared liner has a thickness of 246 mm, a unit area weight of 2612 kg, a hardness of 393 HBW, an unnotched impact energy of 62 J, and a tensile strength of 1462 MPa. Compared with Examples 1 and 2, the hardness, impact toughness, and tensile strength of this comparative example are significantly lower. Simultaneously, impact abrasive wear performance tests were conducted using quartz sand with a particle size between 20 and 40 mesh. The impact energy was 2.5 J, and after 10 hours of impact, the percentage of weight loss due to abrasive wear was 0.0256%.

[0061] Comparative Example 2

[0062] The alloy has the following mass percentage composition: C 0.6%, Si 0.3%, Mn 0.9%, Ni 0.1%, Cr 0.2%, Mo 0.25%, Cu 0.1%, Ti 0.01%, Nb 0.02%, P 0.05%, S 0.02%, and the balance Fe and unavoidable impurities. Its preparation includes the following steps:

[0063] (1) Smelting: Accurately calculate the batching according to the composition, and place the raw materials in a medium-frequency induction melting furnace. Use CaO-CaF2 (added at a mass percentage of 0.8% of the total casting volume) for desulfurization, dephosphorization and slag removal. Heat to 1535℃ and pre-deoxidize with pure aluminum wire for 2 minutes (aluminum wire added at a rate of 0.7 kg / ton of steel). Continue to heat the molten steel and perform alloying treatment at 1550℃. Perform final deoxidation on the resulting molten steel. When the molten steel cools down to 1540℃, transfer the resulting molten steel to a ladle, adjust the temperature of the molten steel to 1490℃ and cast to obtain the casting.

[0064] (2) Heat treatment

[0065] Quenching treatment: The casting is heated to 720°C at a heating rate of 60°C / h, held for 100 min, then heated to 830°C at a heating rate of 90°C / h, held for 140 min, and then oil quenched to 50°C.

[0066] First tempering treatment: Heat to 600℃ at a heating rate of 60℃ / h, hold the quenched casting at the temperature for 60 minutes, and then air cool to room temperature.

[0067] Second tempering treatment: The temperature is increased to 400℃ at a heating rate of 60℃ / h. The casting after the first tempering treatment is held at this temperature for 120 minutes and then air-cooled to room temperature. After defect repair and quality inspection, high-carbon corrosion-resistant and wear-resistant semi-automatic ball mill liner steel is obtained.

[0068] The prepared liner had a hardness of 52.8 HRC, an unnotched impact energy of 23 J, and a tensile strength of 1246 MPa. Compared with Examples 1 and 2, the hardness, impact toughness, and tensile strength of this comparative example were significantly lower. Simultaneously, impact abrasive wear performance tests were conducted using quartz sand with a particle size between 20 and 40 mesh. The impact energy was 2.5 J, and after 10 hours of impact, the percentage of weight loss due to abrasive wear was 0.0379%.

[0069] Those skilled in the art should understand that the above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A nano-precipitated phase dispersion reinforced liner casting, characterized in that... The composition includes the following mass percentages: C 0.2–0.6%, Si 0.5–1%, Mn 0.5–1.2%, Cr 1–2%, Mo 0.3–1%, Ni 0.2–0.6%, Ti 0.03–0.1%, V 0.05–0.2%, Nb 0.02–0.07%, N 0–0.02%, La+Ce 0.01–0.06%, P 0–0.02%, S 0–0.02%, with the balance being Fe and unavoidable impurities; the nano-precipitated phases include MoC, V(C,N), NbC, Ti(C,N), and Cr-rich precipitates; The nano-precipitated phases include MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitates in a volume ratio of 4-6:1-3:0.5-1.5:0.5-1.5:0.8-1.2; The nano-precipitates are spherical or ellipsoidal in shape, with a particle size of 10-500 nm.

2. The nano-precipitated phase dispersion reinforced liner casting according to claim 1, characterized in that... The nano-precipitated phases include MoC, V(C,N), NbC, Ti(C,N) and Cr-rich precipitates in a volume ratio of 4.5-5.5:1.5-2.5:0.8-1.2:0.8-1.2:0.9-1.

1.

3. The nano-precipitated phase dispersion reinforced liner casting according to claim 1, characterized in that, The room temperature tensile strength is greater than 2000MPa, the impact toughness is greater than 200J, and the hardness is greater than 52HRC.

4. The method for preparing the nano-precipitated phase dispersion reinforced liner casting according to claim 1, characterized in that... Includes the following steps: (1) Smelting and casting: The ingredients are prepared according to the composition required in claim 1, and smelting is carried out in a medium frequency induction furnace. First, scrap steel, ferromolybdenum, ferroniobium and nickel wire are added to the magnesium sand crucible in sequence and heated to melt. CaO-CaF2 is added to form slag and the slag is removed. The temperature is raised to 1520-1600℃ for pre-deoxidation and final deoxidation. Then ferromanganese, ferrosilicon, ferrochrome and ferrovanadium are added. After holding for 2-20 minutes, the power of the medium frequency induction furnace is adjusted and the temperature is lowered to between 1420-1520℃. Then the molten steel is poured into the sand mold and covered with a heating agent and heat-insulating bricks. After cooling, the cast product is obtained. (2) Quenching treatment: The cast product obtained in step (1) is heated to 600-800℃ and held for 0.1-12h, then heated to 800-1000℃ and held for 0.1-12h, and then oil cooled to room temperature; (3) Tempering treatment: The quenched product is heated to 150-600℃, held for 0.1-24h and then air-cooled to room temperature to obtain the nano-precipitated phase dispersion reinforced liner casting.

5. The method according to claim 4, characterized in that: In step (1), the sand mold is made of quartz sand, which includes 400 mesh quartz sand and 80 mesh quartz sand, and the volume ratio of 400 mesh quartz sand to 80 mesh quartz sand is 1:7 to 1:

1.

6. The method according to claim 4, characterized in that: In step (2), the ratio of the heat preservation time between 600 and 800°C to the heat preservation time between 800 and 1000°C is 10:1 to 1:

1.

7. The method according to claim 4, characterized in that: In step 1), the smelting holding temperature is 1540-1580℃ and the casting temperature is 1440-1500℃; in step 2), the first stage holding temperature is 650-750℃ and the second stage holding temperature is 820-920℃.

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