Bimetallic wear-resistant lining and preparation method thereof

Abstract

The present invention belongs to the field of bimetallic composite casting technology, and specifically discloses a bimetallic wear-resistant lining plate and its preparation method, including: S1, melting of molten metal; S2, molding: using an upper box and a lower box to form a cavity, the cavity is provided with independent iron runners and steel runners; S3, pouring: first injecting low-alloy steel liquid into the cavity, the pouring temperature is 1541℃~1555℃, and then injecting high-chromium cast iron liquid into the cavity after an interval, the pouring temperature is 1486℃~1500℃; S4, heat treatment: heating to 1050℃~1080℃ with the furnace, keeping warm for 60~80min, then cooling the furnace to 980℃~1000℃, soaking for 80~90min, taking out of the furnace, and spray quenching. The present invention adopts the above-mentioned bimetallic wear-resistant lining plate and its preparation method, and uses the molten steel in the slag collecting trough to avoid heat dissipation around the base layer. During the pouring process, the air is isolated to avoid oxidation, the interface is purified, and the metallurgical composite is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of bimetallic composite casting, in particular to a bimetallic wear-resistant liner and a preparation method thereof. Background Art

[0002] The wear-resistant lining of a crusher is a wear-resistant and consumable part. Its service life and replacement frequency directly determine the crusher's operating efficiency and product cost. Wear-resistant liners made of a single material, such as high-manganese steel and high-chromium cast iron, have low procurement costs but high operating costs. High-manganese steel has good toughness but is not resistant to friction and wear. It is suitable for work environments with large impacts. Under the action of impact, austenite transforms into martensite, improving wear resistance. High-chromium cast iron has high hardness but is very brittle. It is suitable for work environments with large friction and wear. For crushing conditions that involve both impact and wear, bimetallic composite liners are often used. They are made of a combination of low-alloy steel with good toughness and high-chromium cast iron with high hardness, taking into account the conflicting performance of toughness and wear resistance.

[0003] In the prior art, there are many composite methods for bimetallic composite liners, such as casting, surfacing, explosion welding, coating, plasma spraying, etc., among which casting is the most economical method, especially suitable for workpieces with thicker wear-resistant layers. However, for plate castings, due to their shape and size constraints, bimetallic metallurgical composite is more difficult, and most invention patents for plate castings have the problem of low operability. For example, the invention patent application with publication number CN101357398A discloses a production process method for double-liquid bimetallic composite casting jaw plates, which uses two pouring systems to first pour high-chromium cast iron, and then pour low-alloy steel in a rain-like manner after an interval. This method will cause serious oxidation of the molten steel, and it is not easy to ensure the casting quality and performance of the low-alloy steel. The invention patent with publication number CN1039204C discloses a method for composite casting of jaw plates using liquid high-chromium cast iron and cast steel. Similarly, high-chromium cast iron is first poured, and cast steel is poured after solidification. This method does not consider the problem of composite surface temperature distribution or uniformity of plate parts. Patent application number CN104174833B discloses a process for producing wear-resistant thin plates using a dual-liquid bimetallic composite casting. This dual-casting system uses a special chilling material to adjust the temperature field of the molten metal within the mold cavity, resulting in a larger temperature gradient in the area where the molten metal contacts the chilling material and a smaller temperature gradient in the area away from it. When the low-alloy steel with the larger temperature gradient has formed a solid phase and the surface of the area with the smaller temperature gradient is in a solid-liquid or liquid phase, high-chromium cast iron is poured into the remaining space in the mold cavity, achieving a metallurgical bond between the two molten metals without mixing. However, this process cannot precisely control the thickness of the low-alloy steel layer during the initial casting. Patent application number CN115870480A discloses a process for producing jaw plates using a dual-liquid bimetallic composite casting. A chiller is placed at the bottom of the mold cavity, and high-chromium cast iron is poured into the cavity between the lower and upper transition boxes. The upper transition box is then removed, the upper box is closed, and the molten steel is poured again. This process requires the unpacking and packing of the boxes to be performed in short intervals, which is labor-intensive. The invention patent with publication number CN111195711B discloses a bimetallic composite method for gyratory crusher liners. Using the same casting system, molten steel and molten iron are poured in sequence, and the pouring height and temperature of the carbon steel layer are determined through an observation hole. One of its disadvantages is that the high-chromium cast iron in the casting system is easily melted with the carbon steel in the casting system during pouring, causing changes in the composition of the high-chromium cast iron. The second disadvantage is that it relies on human experience, resulting in unstable product quality and unsuitable for large-scale industrial production.

[0004] Therefore, in order to obtain high-quality bimetallic metallurgical composite wear-resistant linings, it is necessary not only to work hard on the molten metal smelting and pouring system, but also to work hard on the metallurgical composite interface, such as improving the smelting quality of high-chromium cast iron to enhance its toughness, using overflow ports to ensure the thickness of the base layer, purifying the metallurgical composite interface to avoid oxidation, and controlling the consistency of the interface temperature by controlling the cooling rate. The invention patent with publication number CN117483722B discloses a method for manufacturing bimetallic wear-resistant thin plates, which uses a wing cavity to slow down the heat dissipation around the molten metal and uses cold iron to strengthen one-way heat transfer so that the interface temperature is uniform. The outside of the wing cavity is connected to the overflow port to control the base casting thickness. Protective gas is introduced into the cavity to prevent oxidation during the molten steel rain pouring process and to purify the interface. The interval time is simulated by computer, and the temperature of the interface simulation is given as the solid-liquid two-phase region temperature. However, after the base layer solidifies, the wear-resistant layer metal liquid cannot re-melt the base layer to form a metallurgical composite. Metallurgical composite can only be formed when the base layer is in a semi-solidified state (solid-liquid coexistence) or liquid state. If the upper surface of the base layer metal liquid, that is, the interface, is in a liquid state, it will cause over-melting.

[0005] In addition, the metallurgical compounding described in the invention patent with publication number CN117483722B refers to the compounding of liquid and liquid, i.e., the process of cast crystallization growing from the base layer to the wear-resistant layer, and does not include the metallurgical compounding produced by atomic diffusion. As the thickness of the wear-resistant liner increases, the rapid cooling ability of the chill decreases as its heating temperature increases, the difficulty of controlling the unidirectional solidification of the wear-resistant plate gradually increases, and the uniformity of the interface deteriorates. Especially when a protective gas is introduced, once the interface solidifies, it is impossible to feed the base layer, resulting in shrinkage defects in the base layer and the resulting waste. Therefore, it is necessary to improve the above method to obtain a production process for thicker bimetallic wear-resistant liners. Summary of the Invention

[0006] The purpose of the present invention is to provide a bimetallic wear-resistant lining and a preparation method thereof, which utilizes the molten steel in the slag collecting trough to avoid heat dissipation around the base layer, and the base layer molten steel dissipates heat in two directions. The interface retains local high temperature as a shrinkage feeding channel for the base layer molten steel. During the casting process, the cavity is isolated from air to avoid oxidation, purify the interface, and obtain metallurgical composite.

[0007] To achieve the above object, the present invention provides a method for preparing a bimetallic wear-resistant liner, comprising the following steps:

[0008] S1. Melting of molten metal: Using high chromium cast iron as the wear-resistant layer and low alloy steel as the base layer, two medium frequency furnaces are used to melt high chromium cast iron and low alloy steel respectively to obtain high chromium cast iron liquid and low alloy steel liquid;

[0009] S2. Molding: A sand box is formed by combining an upper box and a lower box, with a mold cavity between the upper and lower boxes. The sand box is provided with independent iron runners and steel runners to ensure the respective casting components and avoid using a single runner to cause mutual melting and affect the high-chromium cast iron component. The parting surface of the sand box is a bimetallic metallurgical composite interface. The inner gate of the steel runner is set on the parting surface of the lower box, and the inner gate of the iron runner is set on the parting surface of the upper box. An overflow port is set on the parting surface of the upper box. The overflow port is connected to a slag collecting trough. Several overflow ports are respectively provided on the opposite sides of the inner gate of the iron runner and the opposite sides of the inner gate of the steel runner to control the casting thickness of the low-alloy steel, thereby ensuring the consistency of the thickness of the liner base. The slag collecting trough is set inside the sand box. The volume of the slag collecting trough below the parting surface is larger than the volume of the steel runner above the parting surface, so as to ensure that the overflow port remains unobstructed after the low-alloy steel liquid stops pouring, and the interface is the lower plane of the overflow port. The slag collecting trough collects the low-temperature oxidized molten steel at the front end of the low-alloy steel liquid pouring, and uses this molten steel to increase the heat dissipation resistance around the base layer. It also collects the low-temperature molten iron with oxidized slag at the front end when high-chromium cast iron is poured, so as to achieve the purpose of a pure interface and consistent interface temperature. The interior of the sand box located above the mold cavity is provided with a blind riser. The lower box is provided with a steel mesh at a position 1 to 3 mm away from the parting surface. The main purpose is to quickly form a solid barrier at the interface to prevent the molten iron and molten steel from mixing.

[0010] S3. Pouring: Cover the opening of the cavity communicating with the outside with agricultural film, first inject the low alloy steel liquid obtained in S1 into the cavity along the steel runner at a pouring temperature of 1541°C to 1555°C, and then inject the high chromium cast iron liquid obtained in S1 into the cavity along the iron runner at a pouring temperature of 1486°C to 1500°C after an interval. The temperature difference of the pouring temperatures is controlled within 15°C to obtain the liner.

[0011] Preferably, low-phosphorus content raw materials or industrial pure alloys are used for melting high-chromium cast iron. After the molten iron is melted, reducing slag is produced, which is then alloyed. After rapid heating, the high-temperature steel slag is mixed into the ladle. Inert gas is introduced into the molten iron through the air permeable plug at the bottom of the ladle, and the molten iron is stirred to promote the contact between the molten iron and the reducing slag, thereby strengthening the desulfurization and deoxidation reactions. At the same time, alloy wire is introduced into the ladle for wire feeding, modification and inoculation treatment. The gas is turned off, the slag is skimmed off and covered with a slag collecting and heat-insulating agent, and the ladle is hoisted to a sand box and left to stand for pouring. The modification and inoculation treatment of high-chromium cast iron and the air blowing refining technology of reducing slag belong to the existing technology, and the purpose is to improve the toughness of high-chromium cast iron from the perspective of reducing inclusions and refining grains.

[0012] Low-alloy steel is melted using low-phosphorus scrap and low-phosphorus alloys. After the molten steel is melted, reducing slag is produced. A silicon-calcium-barium alloy is used as a deoxidizer in the furnace. The barium and calcium significantly improve inclusion morphology, transforming long, strip-like inclusions into fine, spherical ones, thereby improving the toughness of the low-alloy steel. After heating for 4-5 minutes, the hot slag is mixed into the ladle. This mixing increases the contact and reaction interface between the reducing slag and the molten steel, promoting desulfurization and deoxidation reactions. A rare earth magnesium-silicon ferroalloy is pre-placed at the bottom of the ladle to deoxidize the steel. Besides forming inclusions through deoxidation and desulfurization, the remaining rare earth elements dissolve in the molten steel and undergo equilibrium distribution at the growing solid-liquid interface, resulting in enrichment on the liquid side of the solid-liquid interface front. This increases the solute equilibrium distribution coefficient (K) for elements like Mn and reduces segregation. In addition, the addition of elements such as Mg, Ca, and Ba promotes the purification of inclusions, because both Mg and Ca have strong activity and can desulfurize and deoxidize themselves. In particular, the addition of Mg further promotes the spheroidization of inclusions. The combined effect is beneficial to increase the amount of solid-dissolved rare earths in steel, so that the purification effect of rare earths can be further fully exerted.

[0013] Preferably, in S1, the high chromium cast iron comprises the following components by mass percentage:

[0014] 2.6% to 2.8% C, ≤1% Si, 0.6% to 1.2% Mn, 25% to 27% Cr, 0.4% to 0.6% Mo, 0.2% to 0.4% Ni, the balance being Fe and unavoidable impurities; in S1, when the low alloy steel is melted, a silicon calcium barium alloy is used as a deoxidizer in the furnace, and the amount of the silicon calcium barium alloy added is 0.35% to 0.45% of the mass fraction of the low alloy steel liquid in the furnace;

[0015] The deoxidizer in the ladle is a rare earth magnesium ferrosilicon alloy with a size of 3 to 8 mm, and the amount of the rare earth magnesium ferrosilicon alloy added is 0.30% to 0.35% of the mass fraction of the molten steel in the ladle;

[0016] The silicon-calcium-barium alloy includes the following components by mass fraction:

[0017] 38.55%~42.69% Si, 6.60%~7.26% Ba, 18.17%~19.93% Ca, the balance is Fe and trace amounts of other impurities;

[0018] The rare earth magnesium ferrosilicon alloy comprises the following components by mass fraction:

[0019] 6.17%~7.82%RE, 7.05%~8.76%Mg, 35.88%~43.14%Si, ≤1.0%Ti, ≤1.0%Al, the balance is Fe and trace other impurities.

[0020] Adding 0.35% to 0.45% of silicon-calcium-barium alloy and 0.30% to 0.35% of rare earth magnesium-silicon-ferrosilicon alloy to low alloy steel is beneficial to promoting a significant refinement of the solidification structure, a significant reduction in the number of inclusions, and spheroidization of the inclusion morphology, significantly improving the plasticity and toughness of the low alloy steel.

[0021] Preferably, in S2, an inner chiller is provided inside the cavity, the inner chiller is a column-platform structure with an upper column and a lower platform, and a groove is provided at the top of the inner chiller.

[0022] Preferably, in S2, a cavity is provided on the surface of the steel mesh, and the cavity is located below the blind riser. The purpose of providing the cavity is to have a solid-liquid two-phase temperature or a liquid phase temperature locally at the interface. The cavity is used to become a shrinkage feeding channel for the low alloy steel when the high chromium cast iron water is poured, and cooperates with the blind riser to increase the direct vertical pressure of the low alloy steel for shrinkage feeding.

[0023] Preferably, in S2, an observation port is provided above the flask, located on the opposite side of the steel runner and directly above the slag collecting trough. Low-alloy steel pouring can be controlled by weight. The weight displayed on the electronic scale lags behind the pouring weight, with the difference between the two determined by the pouring speed. If cost or pouring quality requirements are stringent, the observation port facilitates monitoring of the molten steel pouring process. The slag collecting trough can be used to adjust to fluctuations in the pouring weight of the molten steel and control thickness, while still ensuring the thickness of the base steel layer.

[0024] Preferably, in S2, an outer chill is provided below the flask. The upper surface of the outer chill has the same shape as the bottom surface of the base layer, and the lower surface of the outer chill is spherical. The thickness of the outer chill near the steel runner is greater than that of the other edges. This facilitates rapid and uniform unidirectional solidification.

[0025] Preferably, after S3, the liner is tempered to obtain a bimetallic liner with no shrinkage cavities in the base layer and metallurgically composited interface.

[0026] Preferably, the tempering treatment is specifically:

[0027] The liner is heated to 1050°C-1080°C in the furnace and kept warm for 60-80 minutes to allow the high temperature to diffuse evenly and reduce casting segregation. The liner is then cooled to 980°C-1000°C in the furnace and soaked for 80-90 minutes. The liner is taken out of the furnace and spray quenched on the high chromium cast iron side of the liner. The cooling rate of the spray quenching is controlled at 25-32°C / s. When the surface temperature of the low alloy steel side of the bimetallic liner is cooled to below 250°C, the liner is sent to a heat treatment furnace at 200°C-250°C for tempering and keeping warm for 5-8 hours. The liner is then taken out of the furnace and air-cooled to room temperature.

[0028] The principle of spray quenching is to spray a mist mixture of water and air onto the workpiece surface. Contact between the mist droplets and the workpiece results in rapid cooling. This process involves four key heat transfer stages: stable film boiling, transition boiling, nucleate boiling, and natural convection. Optimizing heat transfer in these stages can significantly improve cooling efficiency. The cooling rate of spray quenching depends primarily on the spray density of the coolant—that is, the mass flow rate of the coolant per unit area per unit time. Spray quenching avoids the formation of a vapor film as seen in conventional hydrostatic quenching, thereby improving cooling capacity and increasing the depth of the hardened layer. This prevents quenching of areas not requiring hardening and reduces the tendency to crack. Spray quenching is performed only on the high-chromium cast iron side of the liner, improving its hardness and wear resistance. The low-alloy steel side of the liner is cooled naturally without spray quenching, effectively normalizing the liner. Cooling produces fine pearlite, giving the low-alloy steel side high strength and toughness. When the surface temperature of the low alloy steel side cools down to below 250℃, the high chromium cast iron has been hardened and the internal temperature of the low alloy steel base is slightly higher. The liner is immediately sent to the heat treatment furnace for stress relief treatment to stabilize the structure.

[0029] Preferably, in S3, the openings connecting the cavity to the outside include an iron runner, a steel runner and an observation port.

[0030] Preferably, before pouring low-alloy steel, cover the mold with plastic film to completely cover the air passages between the mold cavity and the outside world. This allows air inside the cavity to escape while preventing outside air from entering. This reduces oxidation of the molten steel and maintains a clean interface. To prevent molten steel splashing and scalding the plastic film, a layer of sand can be applied. The plastic film around the pouring port and observation port should be covered with refractory wool for ease of operation.

[0031] Preferably, in S3, the temperature difference of the pouring temperature is controlled within 15°C. When pouring low-alloy steel molten steel, the purpose is to obtain the same interval time. That is, the pouring temperature and the steel mesh are together. Within the same interval time, the temperature of the low-alloy steel interface is at the ideal temperature controlled when pouring high-chromium cast iron molten steel, that is, at the solidus temperature. The interval time is the time from the completion of the low-alloy steel molten steel pouring to the start of the high-chromium cast iron molten steel pouring. This interval time is based on the time verified by computer simulation and actual pouring. Once determined, it shall not be changed at will. Only when the simulated boundary conditions change significantly, such as changes in the molding sand or steel mesh, shall it be corrected under the guidance of a technician. Such control avoids the influence of human factors of the operator. When pouring high-chromium cast iron, the purpose is to strictly control the quality of the bimetallic metallurgical composite interface to avoid low-temperature infusibility or high-temperature overmelting. Since the interval time has been determined, it is easier to control the pouring temperature of the high-chromium cast iron molten steel alone, which facilitates the pouring operation.

[0032] Preferably, when pouring low-alloy steel liquid, the filling state of the molten steel is observed through the observation port. When the overflow port is bright, the pouring is stopped, and the molten steel in the runner continues to fill the mold under the action of gravity, and the excess molten steel in the mold cavity flows into the slag collecting trough from the overflow port. Alternatively, pouring weight control is adopted instead of using the observation port. After the low-alloy steel liquid is stable, the overflow port remains unobstructed, and the inner cavity of the slag collecting trough below the parting surface must not be filled. After an interval, high-chromium cast iron water is poured. The high-chromium cast iron water flushes part of the oxidized slag on the interface into the slag collecting trough, and part of the oxidized slag flows into the blind riser with the molten steel. The flowing high-chromium cast iron water purifies the interface, and the temperature tends to be consistent, which provides a basis for metallurgical bonding.

[0033] The solidified low-alloy steel interface undergoes diffusion fusion or liquid-liquid fusion with the high-temperature, high-chromium cast iron, forming a metallurgical bond. The hollow areas at the interface serve as feeding channels for the low-alloy steel. The high-chromium cast iron feeds the shrinkage cavities in the low-alloy steel, preventing shrinkage defects.

[0034] The present invention also provides a bimetallic wear-resistant lining.

[0035] Therefore, the present invention adopts the above-mentioned bimetallic wear-resistant lining plate and its preparation method, and the beneficial effects are as follows:

[0036] (1) The process of the present invention has good operability and a high product qualification rate. In terms of molding, agricultural film is used to block the air outside the cavity. The cavity is isolated from the air to avoid oxidation of the molten steel at the interface. The interface is pure and the interval time is fixed, which improves the process operability. The cooling rate of the molten steel is controlled, and then the interface temperature and uniformity are controlled. The pouring temperature is controlled in a narrow range, and the product quality is guaranteed. A bimetallic wear-resistant liner with good metallurgical bonding is obtained. In terms of heat treatment, the high-chromium cast iron side is spray quenched, and the low-alloy steel side is naturally cooled and normalized. The expected performance is obtained at different cooling rates. The heat treatment operation is convenient and feasible, and the product performance is excellent.

[0037] (2) The present invention utilizes a slag collecting trough to collect low-temperature molten steel and low-temperature molten iron with oxidized slag at the front end. The molten steel avoids heat dissipation around the base layer, and the base layer molten steel dissipates heat in two directions. The interface retains local high temperature as a shrinkage-feeding channel for the base layer molten steel. In order to obtain good metallurgical composite and ensure the density of the base layer (no shrinkage holes), the slag collecting troughs on both sides and the cross runners on both sides greatly increase the thermal resistance of the heat dissipation around the low alloy steel, strengthen the heat dissipation in the thickness direction of the plate, and thus obtain a temperature-uniform interface.

[0038] (3) The present invention utilizes a steel mesh to generate a high-temperature barrier layer, thereby avoiding the mixing of molten iron and molten steel, ensuring the stable control of the high-chromium cast iron composition, and thus obtaining stable wear-resistant layer performance. In addition, the high-temperature solid state is conducive to atomic diffusion and liquid mutual melting to form a metallurgical bond; the cavities become shrinkage-feeding channels for the molten steel, the thicker base layer has no shrinkage defects, and the bimetallic composition is well controlled, ensuring the stability of the wear-resistant layer performance.

[0039] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the sand box structure of a bimetallic wear-resistant liner and a preparation method thereof according to a first embodiment of the present invention;

[0041] Figure 2 This is a top view of a bimetallic wear-resistant liner and a preparation method thereof according to a first embodiment of the present invention;

[0042] Figure 3 This is a side view of an embodiment of a bimetallic wear-resistant liner and a method for preparing the same according to the present invention;

[0043] Figure 4 This is a schematic diagram of the sand box structure of a second embodiment of a bimetallic wear-resistant liner and a preparation method thereof according to the present invention;

[0044] Figure 5 This is a microscope image of Example 3 of a bimetallic wear-resistant lining plate and a preparation method thereof according to the present invention, wherein (a) is the base layer and (b) is the wear-resistant layer;

[0045] Figure 6 This is a microscope image of the interface of Example 3 of a bimetallic wear-resistant liner and a preparation method thereof according to the present invention.

[0046] Reference numerals

[0047] 1. Steel pouring channel; 2. Blind riser; 3. Iron pouring channel; 4. Observation port; 5. Slag collecting trough; 6. Overflow port; 7. Steel mesh; 8. External chiller; 9. Cavity; 10. Internal chiller. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0049] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0050] Example 1

[0051] This embodiment is applicable to bimetallic wear-resistant liners with a base thickness exceeding 30 mm. Bimetallic wear-resistant liners have a replacement cycle. In order to ensure that wear-resistant liners of different thicknesses have basically the same wear-resistant life, the thickness of the wear-resistant layer tends to be consistent. For thicker bimetallic wear-resistant liners, the base thickness is correspondingly increased, and the amount of high chromium cast iron used is relatively small, which is beneficial to reducing the material cost of the alloy.

[0052] A bimetallic wear-resistant lining, the preparation method of which is as follows:

[0053] 1. Melting of molten metal

[0054] The high chromium cast iron of the wear-resistant layer and the low alloy steel of the base layer are melted separately in two medium frequency furnaces.

[0055] The pouring composition of high chromium cast iron (sampling in the ladle) is: 2.71% C, 0.68% Si, 0.92% Mn, 26.7% Cr, 0.51% Mo, 0.32% Ni, and the balance is Fe and unavoidable impurities.

[0056] The pouring composition of low alloy steel molten steel is (sampling from the furnace): 0.22% C, 0.38% Si, 0.65% Mn, 0.74% Cr, and the balance is Fe and unavoidable impurities.

[0057] The raw material for melting low-alloy steel into the furnace is high-quality scrap steel, and low-phosphorus alloys are preferably used for alloying. After the molten steel is melted, a deoxidizer is first added, followed by lime, bauxite, and fluorite. The temperature is then rapidly raised to melt the reducing slag. A silicon-calcium-barium alloy is used as the deoxidizer, added at a rate of 0.45% by mass of the molten steel in the furnace. The silicon-calcium-barium alloy comprises 38.55% to 42.69% Si, 6.60% to 7.26% Ba, and 18.17% to 19.93% Ca, with the remainder being Fe and trace amounts of other impurities. Alloying is then performed, and after heating for 5 minutes, the high-temperature slag is mixed into the ladle. This mixing increases the contact and reaction interface between the reducing slag and the molten steel, promoting desulfurization and deoxidation reactions. In this example, the silicon-calcium-barium alloy comprises 40.55% Si, 6.78% Ba, and 19.31% Ca, with the remainder being Fe and trace amounts of other impurities.

[0058] A rare earth magnesium ferrosilicon alloy is placed at the bottom of the ladle for deoxidation within the ladle. Its chemical composition and mass fractions are: 6.17%-7.82% RE (La+Ce), 7.05%-8.76% Mg, 35.88%-43.14% Si, ≤1.0% Ti, ≤1.0% Al, with the remainder being Fe and trace amounts of other impurities. The rare earth magnesium ferrosilicon alloy is sized 3-8 mm and added in an amount equal to 0.30% of the mass fraction of the molten steel. After the steel in the ladle has settled, it is skimmed and covered with a slag-collecting and heat-insulating agent, then hoisted to a flask and allowed to rest before pouring. In this example, the rare earth magnesium ferrosilicon alloy is sized 7 mm and has a chemical composition and mass fractions of: 6.87% RE (La+Ce), 8.12% Mg, 38.95% Si, 0.54% Ti, 0.19% Al, with the remainder being Fe and trace amounts of other impurities.

[0059] The raw materials used to melt high-chromium cast iron include low-phosphorus scrap steel, recarburizer, recycled material, pig iron, high-carbon ferrochrome, or commercially pure alloys. After complete melting, deoxidizers, lime, bauxite, and fluorite are added to create a reducing slag. This is then alloyed, and after rapid heating, the high-temperature slag is mixed and discharged into the ladle. A vent plug is installed at the bottom of the ladle to connect to an inert gas supply. After tapping, argon or nitrogen inert gas is introduced through the vent plug to promote agitation, enhance contact between the molten iron and the reducing slag, and strengthen the desulfurization and deoxidation reactions. Simultaneously with the gas injection, alloy wire is fed into the ladle for wire feeding, modification, and inoculation. Once the process is complete, the gas is turned off, the slag is skimmed, covered with a slag-collecting and heat-insulating agent, and hoisted to a sandbox for placement before pouring.

[0060] High chromium cast iron water adopts a combination of metamorphic inoculation treatment and reducing slag air blowing refining, the purpose of which is to improve the toughness of high chromium cast iron from the perspective of reducing inclusions and refining grains.

[0061] 2. Modeling

[0062] The molding is done in a sand box, such as Figure 1-Figure 3 As shown, the flask comprises an upper and lower box, each formed by combining them. The cavity is formed between the upper and lower boxes, and the parting surface between the upper and lower boxes is a bimetallic metallurgical interface. The flask includes a steel runner 1, a blind riser 2, an iron runner 3, an observation port 4, an overflow port 6, a slag trough 5, a steel mesh 7, and an external chiller 8. The steel runner 1 and the iron runner 3 are independently positioned on either side of the flask. The steel runner 1 is used to pour low-alloy steel liquid, while the iron runner 3 is used to pour high-chromium cast iron liquid. Their runners cover the lateral heat dissipation surfaces of the cavity. The inner gate of the steel runner 1 is located on the parting surface of the lower box, while the inner gate of the iron runner 3 is located on the parting surface of the upper box. An overflow port 6 is provided on the parting surface of the upper box. Several overflow ports 6 are provided on the opposite side of the inner gate of the iron runner 3 and the opposite side of the inner gate of the steel runner 1. The overflow ports 6 connect the mold cavity and the slag collecting trough 5. The length of the slag collecting trough 5 covers the lateral heat dissipation surface of the mold cavity. The mold cavity is surrounded by two cross runners and two slag collecting troughs 5, and its lateral heat dissipation is restricted. The volume of the slag collecting trough 5 below the interface is greater than the volume of the molten steel in the steel runner 1 above the interface, or greater than the volume of the steel runner 1 above the interface, to ensure that the overflow port 6 remains unobstructed after the low-alloy steel liquid stops pouring. The lower plane of the overflow port 6 is the interface. In order to facilitate the observation of the flow of low-alloy steel liquid, an observation port 4 is provided above the sand box, on the opposite side of the steel runner 1, and directly above the slag collecting trough 5. A blind riser 2 is provided inside the sand box above the mold cavity to compensate for the shrinkage of high-chromium cast iron liquid. The slag collecting trough 5 and the blind riser 2 are not exposed to the outside, so as to reduce the flow exchange with the outside air and avoid excessive oxidation of the molten steel at the interface.

[0063] A steel mesh 7 is placed within the mold cavity, 1 to 3 mm below the parting surface. Large cavities 9 are machined into the steel mesh 7. An external chiller 8 is installed beneath the flask (on the bottom of the lower flask). Its upper surface is shaped identically to the base layer, while its lower surface is spherical. The thickness of the chiller 8 near the steel runner 1 is greater than that at the other edges. This enhances cooling of the hot molten steel and areas where heat is not readily dissipated, ensuring uniform temperature at the interface. The cavities 9 in the steel mesh 7 are preferably located below the blind riser 2 to increase direct shrinkage pressure for the low-alloy steel. The wire diameter and arrangement of steel mesh 7 are determined by the pouring temperature of the low-alloy steel and the cooling capacity of the molding sand. When using computer software to simulate the interval time, the wire diameter and arrangement are designed simultaneously so that when the high-chromium cast iron is poured, the interface is at a high-temperature solid phase or low-temperature solid-liquid phase temperature (high-temperature solid phase temperature refers to the high-temperature region within the solid phase, and low-temperature solid-liquid phase temperature refers to the low-temperature region within the solid-liquid phase temperature range), that is, near the solidus temperature, to facilitate the formation of a bimetallic metallurgical bond. At the interface of cavity 9, the low-alloy steel is at the solid-liquid phase temperature, providing a channel for shrinkage feeding of the low-alloy steel in the base layer.

[0064] 3. Pouring

[0065] To reduce oxidation of the molten steel and achieve a pure interface, plastic film is laid over the flask before pouring, covering the iron runner 3, observation port 4, and vent holes (the vent holes are a standard feature to ensure the smooth escape of gases within the mold cavity). First, low-alloy steel is poured from runner 1 at a pouring temperature of 1554°C. After the low-alloy steel is poured, the inner gate is sealed, completely isolating the mold cavity from the outside air. Only air within the cavity escapes before and after pouring, preventing any outside air from entering. When pouring high-chromium cast iron, the refractory wool is removed, and the plastic film covering runner 3 is then removed with the incoming molten iron.

[0066] During the molten steel pouring process, pay attention to observing the color of the overflow port 6 from the observation port 4. When the overflow port 6 is bright, stop pouring and the molten steel in the steel runner 1 continues to fill the mold under the action of gravity. Alternatively, the observation port 4 may not be set, and the filling of the low-alloy steel molten steel can be controlled by controlling the pouring weight. The molten steel at the front end of the filling process comes into contact with the air in the mold cavity and contains oxidized slag, and becomes low-temperature molten steel after flowing through the mold cavity. The subsequent flowing filling molten steel will squeeze the front molten steel from the overflow port 6 into the slag collecting trough 5. The molten steel in the filling cavity is high-temperature molten steel with no oxidation or very little oxidation, which is conducive to obtaining a pure interface with good temperature uniformity.

[0067] The functions of setting up the slag collecting trough 5 are: first, to collect the low-temperature molten steel with oxidized slag at the front end to obtain a more ideal interface; second, to collect the low-temperature molten iron with oxidized slag at the front end of the high-chromium cast iron casting to strengthen the flow of molten iron on the interface; third, to ensure the thickness of the base layer is consistent, and the excess molten steel flows into the slag collecting trough 5; fourth, to avoid heat dissipation around the plate, so that the low-alloy steel molten steel is mainly dissipated in the up and down directions. After the low-alloy steel is poured, molten steel exists on three sides, the molten steel pouring runner and two slag collecting troughs 5, and the other side is a hollow molten iron runner that is closed to the outside world. The heat dissipation thermal resistance of the four sides is greatly increased. The above functions of the slag collecting trough 5 make the actual conditions consistent with the simulated boundary conditions, thereby ensuring the correctness of the interval time and obtaining an ideal metallurgical bond.

[0068] Before the high-chromium cast iron is poured, the low-alloy steel solidifies bidirectionally. The outer chiller 8 at the bottom layer dissipates heat downward, while the steel mesh 7 at the interface acts as the inner chiller 10, rapidly cooling the molten steel. Because the mold cavity is isolated from the outside world and lacks low-temperature gas flow, the temperature difference between the steel mesh 7 and the molten steel decreases, and the temperature drop at the interface gradually decreases, with downward heat dissipation being the primary factor. After the process interval has expired, the high-chromium cast iron is poured from the runner 3 at a pouring temperature of 1487°C. At this point, the interface where the steel mesh 7 is positioned is either a high-temperature solid phase or a low-temperature solid-liquid two-phase phase, meaning it is near the solidus temperature. This acts like a high-temperature partition within the mold cavity, isolating the molten iron from mixing with the base layer of molten steel. The cavities 9 at the steel mesh 7, where the interface is a low-temperature liquid phase, serve as a feeding channel for the low-alloy steel after the molten iron is poured. Even at temperatures in the solid-liquid two-phase region, the high-temperature soft shell of the solidified crust lacks strength and collapses under the pressure of the molten iron, forming a feeding channel for the low-alloy steel. The blind riser 2, located above the cavity 9, increases the vertical pressure required to feed the low-alloy steel. Once the molten iron enters the shrinkage cavities of the solidified molten steel in the base layer through the feeding channel, it becomes stationary and stops flowing, preventing severe overmelting with the molten steel and affecting the high-chromium cast iron composition of the wear-resistant layer. After the high-chromium cast iron is poured, the plastic film is removed, and the blind riser 2 is connected to the outside atmosphere through a vent hole, utilizing atmospheric pressure to increase the feeding pressure.

[0069] The molten iron at the front end of the high-chromium cast iron pour flows through the interface, carrying the oxide slag on the interface through the overflow port 6 into the slag collecting trough 5, thereby achieving a clean interface. Furthermore, during the high-chromium cast iron filling process, the molten iron flows at the interface. Even if the oxide slag on the interface does not all flow into the slag collecting trough 5, it will be carried up and floated into the blind riser 2, achieving the purpose of a clean interface. Furthermore, the flow of molten iron helps to uniformize the interface temperature, facilitating the metallurgical bonding of the entire interface. Ultimately, a bimetallic liner with no shrinkage cavities in the base layer and a metallurgically composite interface is formed.

[0070] After unpacking, the small pieces of scrap steel in the steel runner 1 are recycled to melt low-alloy steel, and the recycled materials from the blind riser 2, slag trough 5, and iron runner 3 can be directly recycled to melt high-chromium cast iron molten iron, without any waste or inability to recycle.

[0071] 4. Heat treatment

[0072] The cleaned bimetallic wear-resistant liner is heated in the furnace to 1080°C and held for 60 minutes to achieve high-temperature homogenization and reduce casting segregation. The liner is then cooled to 1000°C and held for 80 minutes. After removal from the furnace and stable suspension, the high-chromium cast iron side of the liner is spray quenched at a cooling rate of 25°C to 30°C / s. The low-alloy steel side is cooled naturally, equivalent to normalizing. When the surface temperature of the low-alloy steel side reaches 250°C, the liner is immediately transferred to a 250°C heat treatment furnace, held for 5 hours, and then removed from the furnace and air-cooled to room temperature, resulting in the bimetallic wear-resistant liner.

[0073] Example 2

[0074] This embodiment is suitable for a bimetallic wear-resistant lining plate having a base layer thinner than that prepared in the first embodiment, and a bimetallic wear-resistant lining plate having a base layer thickness of 15-30 mm is obtained.

[0075] The difference between the preparation method and the first embodiment lies in the difference in the chill, as follows:

[0076] 1. Melting of molten metal

[0077] The pouring composition of high chromium cast iron (sampling in the ladle) is: 2.77% C, 0.41% Si, 1.18% Mn, 25.5% Cr, 0.56% Mo, 0.22% Ni, and the balance is Fe and unavoidable impurities.

[0078] The pouring composition of low alloy steel molten steel is (sampling in the furnace): 0.25% C, 0.54% Si, 0.73% Mn, 0.47% Cr, and the balance is Fe and unavoidable impurities.

[0079] 2. Modeling

[0080] In this embodiment, Figure 4 As shown, the outer chiller 8 of Example 1 is replaced with an inner chiller 10. The inner chiller 10 is a column-and-pedestal structure, with a small-diameter column at the top and a large-diameter platform at the bottom. A groove or cross-slot is provided at the top end of the column to support the steel mesh 7, while the large-diameter platform at the bottom provides stable support for the steel mesh 7, preventing it from tilting due to molten steel erosion. This structure is also suitable for bidirectional solidification of low-alloy steel.

[0081] 3. Pouring

[0082] Low alloy steel liquid is poured from steel runner 1 at a pouring temperature of 1548°C. After the process interval is reached, high chromium cast iron liquid is poured from iron runner 3 at a pouring temperature of 1498°C.

[0083] 4. Heat treatment

[0084] The cleaned bimetallic wear-resistant liner is heated in the furnace to 1050°C and held for 80 minutes to achieve high-temperature homogenization and reduce casting segregation. The liner is then cooled to 980°C and held for 90 minutes. After removal from the furnace and stable suspension, the high-chromium cast iron side of the bimetallic wear-resistant liner is spray quenched at a cooling rate of 27-32°C / s. The low-alloy steel side is allowed to cool naturally, equivalent to normalizing. Once the surface temperature of the low-alloy steel side has cooled to 200°C, the bimetallic wear-resistant liner is immediately tempered in a 200°C heat treatment furnace, held for 8 hours, and then removed from the furnace and air-cooled to complete the bimetallic wear-resistant liner.

[0085] Example 3

[0086] This embodiment is suitable for a bimetallic wear-resistant lining plate which is thinner than the bimetallic wear-resistant lining plate prepared in the second embodiment, and has a base thickness of less than 15 mm.

[0087] The difference between the preparation method and the first embodiment is that no chill is used, and the details are as follows:

[0088] 1. Melting of molten metal

[0089] The pouring composition of high chromium cast iron (sampling in the ladle) is: 2.62% C, 0.91% Si, 0.64% Mn, 26.7% Cr, 0.42% Mo, 0.37% Ni, and the balance is Fe and unavoidable impurities.

[0090] The pouring composition of low alloy steel molten steel is (sampling in the furnace): 0.27% C, 0.42% Si, 0.69% Mn, 0.42% Cr, and the balance is Fe and unavoidable impurities.

[0091] 2. Modeling

[0092] This embodiment does not use a chiller. The cavity structure is similar to that of the first embodiment, but without the external chiller 8. The steel mesh 7 is supported by multiple mesh wires. To prevent tilting due to molten steel erosion, the supporting mesh wires can be inserted into the sand mold at the bottom of the cavity. Because the base layer is thinner, the molten steel solidifies in a essentially paste-like state, eliminating the shrinkage-feeding issue of low-alloy steel. Therefore, the steel mesh 7 does not have cavities 9.

[0093] 3. Pouring

[0094] Low alloy steel liquid is poured from steel runner 1 at a pouring temperature of 1541°C. After the process interval is reached, high chromium cast iron liquid is poured from iron runner 3 at a pouring temperature of 1492°C.

[0095] 4. Heat treatment

[0096] The cleaned bimetallic wear-resistant liner is heated in the furnace to 1065°C and held for 70 minutes to achieve high-temperature homogenization and reduce casting segregation. The liner is then cooled to 990°C and held for 85 minutes. After removal from the furnace and stable suspension, the high-chromium cast iron side of the liner is spray quenched at a cooling rate of 26-30°C / s. The low-alloy steel side is cooled naturally, equivalent to normalizing. Once the surface temperature of the low-alloy steel side cools below 230°C, the liner is immediately tempered in a 230°C heat treatment furnace, held for 6.5 hours, and then removed from the furnace and air-cooled to obtain the bimetallic wear-resistant liner.

[0097] Experimental testing

[0098] 1. The mechanical properties of the bimetallic wear-resistant liners prepared in Examples 1 to 3 were tested, and the test results are shown in Table 1.

[0099] Table 1 Mechanical properties test of bimetallic wear-resistant liner

[0100] ;

[0101] It can be seen from Table 1 that the mechanical properties of each wear-resistant liner are good and meet the use standards of crusher liners.

[0102] 2. The bimetallic wear-resistant lining prepared in Example 3 was subjected to morphology and impact abrasive wear tests as well as crusher trial analysis. The morphology results are as follows: Figure 5 and Figure 6 shown.

[0103] Depend on Figure 5 It can be seen that the bimetallic liner with martensite + carbide + retained austenite structure was successfully synthesized. Figure 6 It can be seen that a bimetallic lining with a pure interface is obtained.

[0104] The impact abrasive wear test used an impact frequency of 100 times / min, a specimen rotation speed of 190 r / min, a test duration of 2 h, quartz sand with a grit size of 20-40 mesh, and an abrasive flow rate of 12 kg / h. The results are shown in Table 2.

[0105] Table 2 Impact abrasive wear test of bimetallic wear-resistant liner

[0106] ;

[0107] It can be seen from Table 2 that the product performance of the bimetallic liner is excellent.

[0108] Therefore, the present invention adopts the above-mentioned bimetallic wear-resistant lining and its preparation method, utilizes the molten steel in the slag collecting trough to avoid heat dissipation around the base layer, the base layer molten steel dissipates heat in two directions, and retains local high temperature at the interface as a shrinkage feeding channel for the base layer molten steel. During the casting process, the cavity is isolated from the air to avoid oxidation, purify the interface, and obtain metallurgical composite.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a bimetallic wear-resistant lining, characterized in that: The following steps are involved: S1: Molten metal melting: High chromium cast iron is used as the wear-resistant layer, and low alloy steel is used as the base layer, which are melted separately to obtain high chromium cast iron liquid and low alloy steel liquid; S2: Molding: A sand box is formed by combining an upper box and a lower box, wherein a mold cavity is formed between the upper box and the lower box, and the sand box is provided with independent iron runners and steel runners. The parting surface of the sand box is a bimetallic metallurgical composite interface, the inner gate of the steel runner is provided on the parting surface of the lower box, the inner gate of the iron runner is provided on the parting surface of the upper box, an overflow port is provided on the parting surface of the upper box, and the overflow port is connected with a slag collecting trough, and several overflow ports are provided respectively on the opposite sides of the inner gate of the iron runner and the opposite sides of the inner gate of the steel runner, and the slag collecting trough is provided inside the sand box, the volume of the slag collecting trough below the parting surface is greater than the volume of the steel runner above the parting surface, a blind riser is provided inside the sand box above the mold cavity, and a steel mesh is provided on the lower box at a position 1 to 3 mm away from the parting surface; S3: Pouring: Cover the opening of the cavity connecting to the outside with agricultural film, first inject the low alloy steel liquid obtained in S1 into the cavity along the steel runner, the pouring temperature is 1541℃~1555℃, and after an interval, inject the high chromium cast iron liquid obtained in S1 into the cavity along the iron runner, the pouring temperature is 1486℃~1500℃, and the temperature difference of the pouring temperature is controlled within 15℃ to obtain the lining plate.

2. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S1, the high chromium cast iron comprises the following components by mass percentage: 2.6%~2.8% C, ≤1% Si, 0.6%~1.2% Mn, 25%~27% Cr, 0.4%~0.6% Mo, 0.2%~0.4% Ni, the balance is Fe and unavoidable impurities; When the low alloy steel is melted, the deoxidizer in the furnace is silicon calcium barium alloy, and the amount of silicon calcium barium alloy added is 0.35% to 0.45% of the mass fraction of the low alloy steel liquid in the furnace; The deoxidizer in the ladle is a rare earth magnesium ferrosilicon alloy with a size of 3 to 8 mm, and the amount of the rare earth magnesium ferrosilicon alloy added is 0.30% to 0.35% of the mass fraction of the molten steel in the ladle; The silicon-calcium-barium alloy includes the following components by mass fraction: 38.55%~42.69%Si, 6.60%~7.26%Ba, 18.17%~19.93%Ca, the balance is Fe and trace amounts of other impurities; The rare earth magnesium ferrosilicon alloy comprises the following components by mass fraction: 6.17%~7.82%RE, 7.05%~8.76%Mg, 35.88%~43.14%Si, ≤1.0%Ti, ≤1.0%Al, the balance is Fe and trace other impurities.

3. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S2, an inner chiller is provided inside the cavity. The inner chiller is a column-and-pedestal structure with an upper column and a lower platform. A groove is provided at the top of the inner chiller.

4. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S2, a cavity is provided on the surface of the steel mesh, and the cavity is located below the blind riser. The cavity forms a shrinkage feeding channel for the low alloy steel when the high chromium cast iron liquid is poured.

5. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S2, an observation port is provided above the flask, and the observation port is located on the opposite side of the steel runner and directly above the slag collecting trough.

6. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S2, an outer chiller is provided under the flask, the upper surface shape of the outer chiller is the same as the bottom shape of the base layer, the lower surface of the outer chiller is spherical, and the thickness dimension of the outer chiller close to the steel runner side is greater than the dimensions of other sides.

7. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: After S3, the liner is tempered to obtain a bimetallic liner with no shrinkage cavities in the base layer and metallurgical composite interface.

8. The method for preparing a bimetallic wear-resistant lining according to claim 7, characterized in that: The tempering treatment is specifically as follows: The liner is heated to 1050°C~1080°C with the furnace, kept warm for 60~80 minutes, then cooled to 980°C~1000°C in the furnace, soaked for 80~90 minutes, taken out of the furnace, and spray quenched on the high chromium cast iron side of the liner. The cooling rate of the spray quenching is controlled at 25~32°C / s. When the surface temperature of the low alloy steel side of the bimetallic liner cools to below 250°C, it is sent to a heat treatment furnace at 200°C~250°C for tempering and keeping warm for 5~8 hours, and then taken out of the furnace and air-cooled to room temperature.

9. The method for preparing a bimetallic wear-resistant lining according to claim 1, characterized in that: In S3, the openings connecting the mold cavity to the outside include an iron runner, a steel runner and an observation port.

10. A bimetallic wear-resistant lining plate prepared by the method for preparing a bimetallic wear-resistant lining plate according to any one of claims 1 to 9.

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