A method for manufacturing a metal crusher guard

Abstract

This invention relates to a method for preparing a metal crusher guard plate, comprising a substrate and a wear-resistant plate layer; the wear-resistant plate layer is attached to one side of the substrate, and the substrate and the wear-resistant plate are metallurgically bonded; the composition of the substrate by weight percentage is: C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe; the composition of the wear-resistant plate layer by weight percentage is: C: 3.5~4.5%, Si: 1.8~2.2%. The composition of the wear-resistant plate is as follows: Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, Mg: 0.02~0.1%, W: 0.02~0.1%, N: 0.005~0.02%, WC: 0.5~0.1%, with the balance being Fe. The preparation process of the wear-resistant plate includes the manufacturing of sand cores and sand molds, the preparation of molten steel for the base material and molten iron for the wear-resistant plate layer, casting and molding, and heat treatment. The wear-resistant plate layer has high hardness and wear resistance, and contains hard particles of tungsten carbide, thereby improving the wear resistance of the wear-resistant plate and extending its service life.

Description

Technical Field

[0001] This invention belongs to the technical field of wear-resistant guard plate preparation methods, specifically relating to a method for preparing a metal crusher guard plate. Background Technology

[0002] Metal crushers are machines that break scrap metal or ore into granular or small pieces through compression, shearing, or bending. The guard plates are crucial components of a metal crusher, protecting the cylinder from the impact and friction of scrap metal or ore. The impact and friction from scrap metal or ore on the guard plates can easily cause them to fail, resulting in a short service life. Currently, common guard plates are made of alloy steel casting, which involves adding alloying elements to the original carbon steel base to improve the guard plate's impact resistance and wear resistance.

[0003] Chinese patent application CN114959498A discloses a "wear-resistant steel liner material for ball mills and its manufacturing method". The chemical composition of the liner is: C: 0.6~0.7%, Si: 0.3~0.8%, Cr: 1.2~2.8%, Mn: 0.9~1.8%, Ni: 0.8~1.5%, Mo: 0.7~0.9%, Nb: 0.1~1.5%, Zr: 0.2~0.5%, Hf: 0.07~0.09%, P and S≤0.03%, with the remainder being Fe. This liner is made of low-alloy steel, which has strong impact resistance but low hardness. During use, the flow and impact of scrap metal or ore from the mine cause rapid wear of the liner, resulting in a short service life. Summary of the Invention

[0004] To improve the wear resistance and extend the service life of the wear plate, this invention provides a method for preparing a wear plate for a metal crusher; to achieve the above objective, the technical solution adopted by this invention is as follows:

[0005] A method for preparing a metal crusher guard plate includes a substrate and a wear-resistant plate layer; the wear-resistant plate layer is attached to one side of the substrate, and the substrate and the wear-resistant plate are metallurgically bonded; the composition of the substrate by weight percentage is: C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe;

[0006] The wear-resistant plate layer comprises the following components by weight percentage: C: 3.5~4.5%, Si: 1.8~2.2%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, Mg: 0.02~0.1%, W: 0.02~0.1%, N: 0.005~0.02%, WC: 0.5~0.1%, with the balance being Fe; the preparation process of the protective plate is as follows:

[0007] (1) Manufacturing of sand core and sand mold: According to the size and structure of the matrix and wear-resistant plate, resin sand molding is used to prepare the matrix sand mold and the wear-resistant plate layer sand mold respectively. When the matrix sand mold and the wear-resistant plate layer sand mold are combined, the matrix cavity and the wear-resistant plate layer cavity are separated by steel plate.

[0008] (2) Preparation of molten steel for the base and molten iron for the wear-resistant plate: molten steel is smelted in a medium-frequency induction furnace. Scrap steel, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, copper or pig iron, and recycled materials are added in proportion to adjust the composition.

[0009] The composition of the base steel is controlled at C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe. With the steel composition qualified and the steel temperature at 1620~1680℃, the medium-frequency induction furnace is tilted to pour the molten steel into the ladle.

[0010] Wear-resistant plate layer molten iron: C: 3.5~4.5%, Si: 1.6~1.8%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, W: 0.02~0.1%, balance Fe; after the molten iron composition is qualified, the tapping temperature is controlled at 1420~1450℃; magnesium nitride and magnesium are placed at the bottom of the molten iron ladle, and ferrosilicon and iron filings are covered on the surface of magnesium nitride and magnesium and compacted. When the molten iron is poured into the ladle, WC is added with the flow.

[0011] (3) Casting: The molten steel of the base and the molten iron of the wear-resistant plate layer are poured into the corresponding base sand mold and wear-resistant plate sand mold at the same time. The pouring temperature of the molten steel is 1580℃~1610℃ and the pouring temperature of the molten iron is controlled at 1380~1420℃. After solidification and cooling, the mold is opened, the gating system and riser are cut off, and the burrs are polished.

[0012] (4) Heat treatment: Heat treatment includes quenching and tempering processes:

[0013] Quenching process: Heat the protective plate in a heating furnace to 780~850℃ and hold for 7~9 hours; then quench in a salt bath at 240~260℃ for 0.5~2 hours.

[0014] Tempering process: Add the protective plate into the tempering furnace, heat to 100~120℃, and hold for 8~12 hours; then cool to room temperature with the furnace.

[0015] The beneficial effects of the preparation method of the metal crusher guard plate of the present invention:

[0016] (1) The metal crusher guard plate is set as a base and a wear-resistant plate layer. The base is located on the outside and has good toughness. The wear-resistant plate layer is in contact with scrap metal or ore and has good wear resistance, thereby extending the service life of the guard plate.

[0017] (2) The matrix material is low alloy steel. The addition of trace amounts of chromium, molybdenum and copper elements dissolves into the matrix lattice, forming hard points or causing lattice distortion, which is beneficial to the tensile strength, hardness and hardenability of the matrix, and makes the matrix structure martensite; the material of the wear-resistant plate layer is set to ductile iron, and carbides such as manganese carbide, molybdenum carbide and chromium carbide are formed, which is beneficial to improving the hardness and wear resistance of the wear-resistant plate layer; and tungsten carbide particles are directly added to form uniform hard points, which further improves the hardness and wear resistance of the wear-resistant plate layer; there is also 0.005~0.02% nitrogen element in the wear-resistant plate layer, which improves the hardenability during the heat treatment process and is beneficial to the formation of bainite or martensite;

[0018] (3) A steel plate is used to separate the base cavity and the wear-resistant plate layer cavity to reduce or avoid cross-flow between molten iron and molten steel during the casting process, thereby reducing the overall performance of the protective plate; after casting and solidification, the steel plate melts and solidifies between the base and the wear-resistant plate layer to form a whole.

[0019] (4) Two sets of medium-frequency induction furnaces are used to add raw materials, melt them, and adjust the composition to meet the requirements of the base steel and the wear-resistant plate layer. After slag making and slag removal, the temperature is adjusted and the iron is taken out of the furnace. During the iron is taken out of the furnace, tungsten carbide is added to the iron in the flow. This is beneficial to the uniform distribution of tungsten carbide particles in the iron and the uniform distribution of hard tungsten carbide particles in the wear-resistant plate layer. This is beneficial to improving the wear resistance of the wear-resistant plate layer. Nitrogen is added in the form of magnesium nitride when the iron is poured into the iron ladle. This reduces or avoids the volatilization of nitrogen during the smelting process and is beneficial to the control of nitrogen content. Under the action of magnesium and ferrosilicon, graphite spheroidization is achieved, reducing the cutting effect of the formed graphite on the wear-resistant plate layer.

[0020] (5) Control the pouring temperature of molten steel at 1580℃~1610℃ and the pouring temperature of molten iron at 1380~1420℃; under the premise of ensuring the fluidity of molten steel and molten iron, reduce the shrinkage and reduce the formation of shrinkage porosity.

[0021] (6) The protective plate is heated at 780~850℃ and kept at that temperature for 7~9h, so that the manganese carbide, molybdenum carbide, chromium carbide and other carbides and graphite are partially dissolved into the matrix of the wear-resistant plate layer, and the carbides are passivated, reducing the cutting of the matrix of the wear-resistant plate layer. This is conducive to the diffusion of chemical elements between the matrix and the wear-resistant layer, and further enhances the metallurgical bonding strength between the matrix and the wear-resistant layer. Cooling in a salt bath at 240~260℃ causes the matrix to form martensite, and the matrix of the wear-resistant plate layer to form lower bainite or martensite. This is beneficial to improving the toughness and wear resistance of the wear-resistant plate layer and the matrix.

[0022] Furthermore, the matrix sand mold and the wear-resistant plate layer sand mold are an integral whole, and the matrix sand mold and the wear-resistant plate layer sand mold are arranged in parallel; the matrix sand mold includes a matrix cavity, a first gating system and a matrix riser, and the wear-resistant plate layer sand mold includes a wear-resistant plate layer cavity, a second gating system and a wear-resistant plate layer riser; the first gating system and the second gating system are located on the same side of the matrix cavity or the wear-resistant plate layer cavity.

[0023] Beneficial effects: Molten steel and molten iron are injected into the base cavity and wear-resistant plate cavity respectively from the first and second gating systems to complete the casting; after casting, high-temperature molten iron or molten steel is injected into the base riser and wear-resistant plate riser to improve the feeding capacity of the base riser and wear-resistant plate riser; setting the first and second gating systems on the same side, when molten steel and molten iron are injected simultaneously, makes the pressure on both sides of the steel plate similar, which is conducive to maintaining the stability of the steel plate position; preventing the steel plate from burning through prematurely and causing mixed flow, thus reducing the overall performance of the protective plate.

[0024] Furthermore: the first casting system and the second casting system respectively include a straight sprue, several horizontal sprues and an inner sprue, the two ends of the horizontal sprue are respectively the inner sprue and the straight sprue, and the other end of the inner sprue is connected to the matrix cavity or the wear-resistant plate cavity; the several horizontal sprues and the inner sprues are arranged at intervals along the axial direction of the straight sprue; a slag collection bag is set above the horizontal sprue.

[0025] Beneficial effects: By setting up several horizontal runners and ingates, a stepped casting system is formed, which enables layered casting of the protective plate during casting. This avoids excessively high temperatures in the base cavity and wear-resistant plate cavity near the ingate, preventing the molten iron or steel from continuing to flow after the steel plate melts, causing mixed flow and reducing the overall performance of the protective plate. Slag collection bags are set on the horizontal runners to collect slag suspended on the surface of the molten steel or iron.

[0026] Furthermore, when molten iron is smelted in a medium-frequency induction furnace, the molten iron is poured into the ladle by tilting the medium-frequency induction furnace. A strainer is extended to the furnace nozzle of the medium-frequency induction furnace, and the strainer is shaken to slowly add WC. WC is in granular form with a particle size of 20 mesh to 10 mesh.

[0027] Beneficial effects: Adding WC in a flow-through manner is beneficial for the uniform distribution of WC in molten iron; after multiple comparative experiments, WC particles with a particle size of 20-10 mesh were selected to avoid complete dissolution of WC in molten iron or during heat treatment, resulting in WC particles that are too small or too large in the wear-resistant plate layer, which is beneficial for improving the wear resistance of the plate.

[0028] Furthermore, a platform is provided at the bottom of the molten iron ladle, which divides the bottom of the molten iron ladle into a first chamber and a second chamber. Magnesium nitride, magnesium, ferrosilicon and iron filings are filled in the first chamber. When the medium frequency induction furnace is tilted, the molten iron rushes into the second chamber.

[0029] Beneficial effects: When molten iron is poured into the ladle, it flows into the second chamber, submerging the first chamber. This prevents the molten iron from directly impacting magnesium nitride, magnesium, ferrosilicon, and iron filings, causing them to tumble and reducing nitrogen and magnesium absorption. This is beneficial for nitrogen absorption and the spheroidization treatment of the molten iron.

[0030] Furthermore, the steel plate is made of the same material as the base material, and the thickness of the steel plate is 0.5~2mm; the surface of the steel plate is degreased and derusted before use.

[0031] Beneficial effects: Through experimental comparison, steel plates with a thickness of 0.5~2mm were selected to prevent the steel plates from melting through prematurely or failing to melt during the casting process; reduce the bonding strength between the wear-resistant plate layer and the substrate; and remove oil and rust from the surface, which is beneficial to improving the bonding strength between the wear-resistant plate layer and the substrate.

[0032] Furthermore, when the steel plate separates the base cavity from the wear-resistant plate cavity, resin sand is inserted into the four sides of the steel plate; after cooling and opening the box, the part of the steel plate that protrudes from the metal crusher guard plate is cut and ground.

[0033] Beneficial effects: Inserting the steel plate into the resin sand around its perimeter ensures a secure fixation, preventing the steel plate from falling off or shifting during the pouring process, and preventing the mixing of molten steel and iron, which would reduce the performance of the protective plate.

[0034] Furthermore, the main components of the salt bath include KNO2, KNO3, NaNO2, and NaNO3, in a weight ratio of KNO2:KNO3:NaNO2:NaNO3 = 8:4:5:3.

[0035] Beneficial effects: Setting the composition of the salt bath to KNO2, KNO3, NaNO2 and NaNO3 in a reasonable ratio makes the mixed salt easy to melt, which is conducive to controlling the salt bath within a reasonable temperature range. Attached Figure Description

[0036] Figure 1 This is one of the metallographic images of the wear-resistant layer after heat treatment prepared by the metal crusher guard plate preparation method of the present invention (100x magnification, uncorroded).

[0037] Figure 2 This is the second metallographic image of the wear-resistant layer after heat treatment prepared by the metal crusher guard plate preparation method of the present invention (1000x magnification after etching).

[0038] Figure 3 The image shows the metallographic structure of the substrate after heat treatment (1000x magnification, etched) prepared using the metal crusher guard plate preparation method of the present invention. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0040] The specific structure of the metal crusher guard plate preparation method of the present invention in Example 1 includes a substrate and a wear-resistant plate layer. The wear-resistant plate layer is attached to one side of the substrate, and the substrate and the wear-resistant plate are metallurgically bonded.

[0041] The composition of the matrix is ​​controlled as follows (by weight percentage): C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%; the remainder is Fe.

[0042] The composition of the wear-resistant plate layer is controlled as follows (by weight percentage): C: 3.5~4.5%, Si: 1.8~2.2%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, Mg: 0.02~0.1%, W: 0.02~0.1%, N: 0.005~0.02%, WC: 0.5~0.1%, with the balance being Fe.

[0043] The preparation process of the protective plate in this embodiment:

[0044] (1) Manufacturing of sand core and sand mold: According to the size and structure of the matrix and wear-resistant plate, resin sand molding is used to prepare the matrix sand mold and the wear-resistant plate layer sand mold respectively. When the matrix sand mold and the wear-resistant plate layer sand mold are combined, the matrix cavity and the wear-resistant plate layer cavity are separated by steel plate.

[0045] In this embodiment, the steel plate is made of the same material as the base material, specifically controlled as follows (by weight percentage): C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe. The steel plate thickness is 1.2mm, and the surface of the steel plate is degreased and derusted before use. Setting the steel plate thickness to 1.2mm prevents premature melting or failure to melt during the casting process; it also prevents the mixing of molten steel and molten iron, which would reduce the overall performance of the protective plate and decrease the bonding strength between the wear-resistant plate layer and the base material. After degreasing and derusting the steel plate surface, the bonding strength between the wear-resistant plate layer and the base material is further improved, and the introduction of oxide slag by the steel plate is reduced. In other embodiments, provided that the steel plate does not melt through prematurely, the thickness of the steel plate is 0.5 mm instead of 1.2 mm; or provided that the steel plate melts, the thickness of the steel plate can be 2 mm instead of 1.2 mm.

[0046] When the steel plate separates the base cavity from the wear-resistant plate cavity, resin sand is inserted into all four sides of the steel plate. After cooling and unpacking, the portion of the steel plate protruding from the metal crusher guard plate is cut and ground. Inserting the steel plate into resin sand on all four sides ensures it is firmly fixed, preventing it from falling off or shifting during casting, and preventing the mixing of molten steel and iron, which would reduce the performance of the guard plate.

[0047] In this embodiment, the matrix sand mold and the wear-resistant plate sand mold are integrated and arranged parallel to each other. The matrix sand mold includes a matrix cavity, a first gating system, and a matrix riser, while the wear-resistant plate sand mold includes a wear-resistant plate cavity, a second gating system, and a wear-resistant plate riser. The first and second gating systems are located on the same side of either the matrix cavity or the wear-resistant plate cavity. Molten steel and molten iron are injected into the matrix cavity and the wear-resistant plate cavity respectively through the first and second gating systems to complete the pouring. After pouring, high-temperature molten iron or molten steel is injected into the matrix riser and the wear-resistant plate riser to improve their feeding capacity. By placing the first and second gating systems on the same side, the simultaneous injection of molten steel and molten iron makes the pressure on both sides of the steel plate similar, which helps maintain the stability of the steel plate position and prevents premature burn-through of the steel plate, thus avoiding mixed flow and reducing the overall performance of the protective plate.

[0048] The first and second gating systems each include a sprue, several horizontal runners, and an ingate. The horizontal runners have an ingate and a sprue at each end, with the other end of the ingate connected to the base cavity or wear-resistant plate cavity. The horizontal runners and ingates are arranged at intervals along the axial direction of the sprue. A slag collection bag is placed above the horizontal runners. By setting several horizontal runners and ingates, a stepped gating system is formed, enabling layered casting of the protective plate during pouring. This avoids excessively high temperatures in the base cavity and wear-resistant plate cavity near the ingate, preventing the molten iron or steel from continuing to flow after the steel plate melts, causing mixing and reducing the overall performance of the protective plate. The slag collection bag on the horizontal runners collects slag suspended on the surface of the molten steel or iron. In other embodiments, provided the process requirements are met, the first and second gating systems are placed on opposite sides instead of on the same side; a set of horizontal runners and ingates are respectively set to form a bottom-pouring gating system instead of the stepped gating system.

[0049] (2) Preparation of molten base steel and molten iron for wear-resistant plate: molten steel is smelted separately using a medium-frequency induction furnace. Scrap steel, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, copper or pig iron, and recycled materials are added in proportion. Pre-furnace spectral analysis is performed, and additional raw materials are added to adjust the composition to meet requirements. At tapping, the composition of the molten base steel is controlled at C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe. Specifically, at tapping: C: 0.41%, Si: 0.21%, Mn: 0.69%, Cr: 0.29%, Mo: 0.19%, Cu: 0.22%, with the balance being Fe.

[0050] The molten iron for the wear-resistant plate layer has the following composition: C: 3.5~4.5%, Si: 1.6~1.8%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, W: 0.02~0.1%, with the balance being Fe. When tapped from the furnace, the composition is: C: 3.90%, Si: 1.76%, Mn: 0.46%, Mo: 0.22%, Cr: 0.32%, Cu: 0.15%, W: 0.06%, with the balance being Fe.

[0051] In this embodiment, after the molten iron composition is qualified, the tapping temperature is controlled at 1437℃. Magnesium nitride and magnesium are placed at the bottom of the molten iron ladle, and ferrosilicon and iron filings are placed on the surface of the magnesium nitride and magnesium, and then compacted. When the molten iron is poured into the ladle, WC is added along with the flow. In other embodiments, the tapping temperature of the molten steel is controlled at any temperature between 1620 and 1680℃, instead of 1652℃. The tapping temperature of the molten iron is controlled at any temperature between 1420 and 1450℃, instead of 1437℃.

[0052] Iron molten metal is smelted using a medium-frequency induction furnace. When pouring the molten metal into the ladle by tilting the furnace, a strainer is used to slowly add granular wastewater (WC) by swirling the strainer near the furnace spout. The WC is in granular form, with a particle size of 20-10 mesh. Adding WC in a flow-through manner promotes uniform distribution within the molten metal. After multiple comparative experiments, WC particles with a particle size of 20-10 mesh were selected to prevent complete dissolution of WC in the molten metal or during heat treatment, thus avoiding excessively small or large WC particles within the wear-resistant plate layer, which improves the wear resistance of the plate.

[0053] A platform is provided at the bottom of the molten iron ladle, dividing the bottom of the ladle into a first chamber and a second chamber. Magnesium nitride, magnesium, ferrosilicon, and iron filings are filled in the first chamber and compacted. When the medium-frequency induction furnace is tilted, the molten iron rushes into the second chamber. When the molten iron is poured into the ladle, it rushes into the second chamber, submerging the first chamber and preventing the molten iron from directly impacting the magnesium nitride, magnesium, ferrosilicon, and iron filings. This causes the magnesium nitride, magnesium, ferrosilicon, and iron filings to tumble, reducing nitrogen and magnesium absorption and facilitating nitrogen absorption and spheroidization of the molten iron. In other embodiments, a groove is formed at the bottom of the molten iron ladle, replacing the platform. Magnesium nitride, magnesium, ferrosilicon, and iron filings are placed in the groove in layers. The mixture of magnesium nitride and magnesium is located at the bottom, ferrosilicon covers the surface of the magnesium nitride and magnesium mixture, and iron filings cover the surface of the ferrosilicon layer, and are compacted.

[0054] (3) Casting and Molding: The molten steel base and the molten iron of the wear-resistant plate layer are simultaneously poured into the corresponding sand molds for the base and wear-resistant plate layers, respectively. The pouring temperature of the molten steel is 1580℃~1610℃, and the pouring temperature of the molten iron is controlled at 1380~1420℃. After solidification and molding, the mold is cooled and opened, the gating system and risers are removed, and the burrs are polished. In the preparation process of this embodiment, the pouring temperature of the molten steel is 1595℃, and the pouring temperature of the molten iron is 1410℃. In other examples, the pouring temperature of the molten steel is any temperature between 1580℃ and 1610℃; and the pouring temperature of the molten iron is any temperature between 1380℃ and 1420℃.

[0055] (4) Heat treatment: Heat treatment includes quenching and tempering processes.

[0056] Quenching process: The protective plate is placed in a heating furnace at 820℃ and held at 820℃ for 8 hours. It is then rapidly immersed in a salt bath with an initial temperature of 245℃. During quenching, the high temperature of the protective plate causes the salt bath temperature to rise rapidly. The quenching time in the salt bath is 1 hour. After quenching, the protective plate is removed from the salt bath and cooled to room temperature in air, completing the quenching process.

[0057] In this embodiment, the main components of the salt bath include KNO2, KNO3, NaNO2, and NaNO3, in a weight ratio of KNO2:KNO3:NaNO2:NaNO3 = 8:4:5:3; specifically, the specific gravity is KNO2:40%, KNO3:20%, NaNO2:25%, and NaNO3:15%. Setting the salt bath components to KNO2, KNO3, NaNO2, and NaNO3 in a reasonable ratio makes the mixed salt easily molten, which is beneficial for controlling the salt bath within a reasonable temperature range. In other embodiments, to meet the temperature requirements of the salt bath, the salt bath includes one or more of KNO2, KNO3, NaNO2, and NaNO3, in any proportion.

[0058] Tempering process: Place the protective plate in the tempering furnace, heat it to 110℃, and keep it at 110℃ for 10 hours; after heating is completed, cool it to room temperature with the furnace.

[0059] Compared with Example 1, the main difference in the preparation method of the metal crusher guard plate of the present invention in Example 2 is that the composition of the base steel and the composition of the wear-resistant plate molten iron are different from those in Example 1 when tapping from the furnace. Specifically, the compositions of both the base steel and the wear-resistant plate molten iron are within the control requirements. The specific composition of the base steel is: C: 0.44%, Si: 0.28%, Mn: 0.73%, Cr: 0.39%, Mo: 0.20%, Cu: 0.21%, with the balance being Fe. The steel composition is qualified, and the tapping temperature of the steel is 1652℃. The medium-frequency induction furnace is tilted to pour the steel into the ladle. The wear-resistant plate molten iron is: C: 4.05%, Si: 1.70%, Mn: 0.45%, Mo: 0.29%, Cr: 0.28%, Cu: 0.17%, W: 0.07%, with the balance being Fe. When tapping from the furnace, the composition of the base steel and the wear-resistant plate molten iron are obtained by adding their respective raw materials and melting them. By adding raw materials, the composition is adjusted, and the specific composition has a certain degree of randomness. As long as it does not exceed the requirements of the base steel composition and the wear-resistant plate molten iron at the time of tapping from the furnace, it is acceptable.

[0060] Compared with Example 1, the main difference in the preparation method of the metal crusher guard plate of the present invention in Example 3 is that the heat treatment temperature setting is different from that in Example 1. During the quenching process, the heating temperature is set to 780℃ or 850℃, and the temperature is held at 780℃ for 9 hours or at 850℃ for 7 hours. After heating, the plate is quickly quenched in a salt bath with an initial salt bath temperature of 240℃, and the quenching time in the salt bath is 0.5 hours or 2 hours. Ignoring the increase in salt bath temperature caused by the high-temperature guard plate, the initial salt bath temperature can also be set to 246℃, and the quenching time in the salt bath can be 0.5 hours or 2 hours.

[0061] An embodiment of the metal crusher guard plate preparation method of the present invention is used to prepare a guard plate. The guard plate includes a substrate and a wear-resistant plate layer, which are metallurgically bonded together with high bonding strength. The substrate is low-alloy steel, and the wear-resistant plate layer is ductile iron containing carbides. Crystal phase observation of the wear-resistant plate layer shows that the graphite in the wear-resistant plate layer is spherical, with a spheroidization rate of ≥95% and a spheroidization level of 1. Specifically, as shown... Figure 1 As shown. After heat treatment, the metallographic matrix of the wear-resistant plate layer is mainly lower bainite, specifically as follows: Figure 2 As shown; the metallographic matrix of the substrate is mainly martensite; specifically as follows... Figure 3 As shown, the wear-resistant plate layer contains tungsten carbide hard particles and hard phases such as manganese carbide, molybdenum carbide, and chromium carbide, which improves the hardness and wear resistance of the wear-resistant plate layer. Graphite exists in a spherical shape, reducing the cutting effect of the formed graphite on the wear-resistant plate layer. During friction, the graphite shedding has a certain lubricating effect. The matrix structure of the wear-resistant plate layer is lower bainite, and the metallographic matrix structure of the matrix is ​​martensite, which has high strength and toughness. The matrix is ​​located on the outer side and has good toughness; the wear-resistant plate layer has good wear resistance when in contact with scrap metal or raw ore, thus greatly extending the service life of the protective plate.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a metal crusher guard plate, characterized in that, It includes a substrate and a wear-resistant plate layer; the wear-resistant plate layer is attached to one side of the substrate, and the substrate and the wear-resistant plate are metallurgically bonded; the composition of the substrate by weight percentage is: C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe; The wear-resistant plate layer comprises the following components by weight percentage: C: 3.5~4.5%, Si: 1.8~2.2%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, Mg: 0.02~0.1%, W: 0.02~0.1%, N: 0.005~0.02%, WC: 0.5~0.1%, balance Fe; Preparation process of the protective plate: (1) Manufacturing of sand core and sand mold: According to the size and structure of the matrix and wear-resistant plate, resin sand molding is used to prepare the matrix sand mold and the wear-resistant plate layer sand mold respectively. When the matrix sand mold and the wear-resistant plate layer sand mold are combined, the matrix cavity and the wear-resistant plate layer cavity are separated by steel plate. (2) Preparation of molten steel for the base and molten iron for the wear-resistant plate: molten steel is smelted in a medium-frequency induction furnace. Scrap steel, ferrosilicon, ferromanganese, ferrochrome, ferromolybdenum, copper or pig iron, and recycled materials are added in proportion to adjust the composition. The composition of the base steel is controlled at C: 0.40~0.45%, Si: 0.15~0.30%, Mn: 0.60~0.75%, Cr: 0.20~0.45%, Mo: 0.10~0.25%, Cu: 0.15~0.25%, with the balance being Fe. With the steel composition qualified and the steel temperature at 1620~1680℃, the medium-frequency induction furnace is tilted to pour the molten steel into the ladle. Wear-resistant plate layer molten iron: C: 3.5~4.5%, Si: 1.6~1.8%, Mn: 0.4~0.5%, Mo: 0.15~0.35%, Cr: 0.25~0.50%, Cu: 0.12~0.20%, W: 0.02~0.1%, balance Fe; after the molten iron composition is qualified, the tapping temperature is controlled at 1420~1450℃; magnesium nitride and magnesium are placed at the bottom of the molten iron ladle, and ferrosilicon and iron filings are covered on the surface of magnesium nitride and magnesium and compacted. When the molten iron is poured into the ladle, WC is added with the flow. (3) Casting: The molten steel of the base and the molten iron of the wear-resistant plate layer are poured into the corresponding base sand mold and wear-resistant plate sand mold at the same time. The pouring temperature of the molten steel is 1580℃~1610℃ and the pouring temperature of the molten iron is controlled at 1380~1420℃. After solidification and cooling, the mold is opened, the gating system and riser are cut off, and the burrs are polished. (4) Heat treatment: Heat treatment includes quenching and tempering processes. Quenching process: Heat the protective plate in a heating furnace to 780~850℃ and hold for 7~9 hours; then quench in a salt bath at 240~260℃ for 0.5~2 hours. Tempering process: Add the protective plate into the tempering furnace, heat to 100~120℃, and hold for 8~12 hours; then cool to room temperature with the furnace.

2. The method for preparing the metal crusher guard plate according to claim 1, characterized in that, The matrix sand mold and the wear-resistant plate layer sand mold are integrated as a whole, and the matrix sand mold and the wear-resistant plate layer sand mold are arranged in parallel. The matrix sand mold includes a matrix cavity, a first gating system and a matrix riser, and the wear-resistant plate layer sand mold includes a wear-resistant plate layer cavity, a second gating system and a wear-resistant plate layer riser. The first gating system and the second gating system are located on the same side of the matrix cavity or the wear-resistant plate layer cavity.

3. The method for preparing the metal crusher guard plate according to claim 2, characterized in that, The first and second casting systems each include a straight gating system, several horizontal gating systems, and an inner gating system. The two ends of the horizontal gating system are the inner gating system and the straight gating system, respectively. The other end of the inner gating system is connected to the matrix chamber or the wear-resistant plate chamber. The several horizontal gating systems and the inner gating systems are arranged at intervals along the axial direction of the straight gating system. A slag collection bag is set above the horizontal gating system.

4. The method for preparing the metal crusher guard plate according to claim 1, characterized in that, When molten iron is smelted in a medium-frequency induction furnace, the molten iron is poured into the ladle by tilting the furnace. A strainer is then placed at the furnace nozzle of the furnace and the strainer is shaken to slowly add WC. The WC is in granular form with a particle size of 20 mesh to 10 mesh.

5. The method for preparing the metal crusher guard plate according to claim 4, characterized in that, A platform is provided at the bottom of the molten iron ladle, which divides the bottom of the ladle into a first chamber and a second chamber. Magnesium nitride, magnesium, ferrosilicon and iron filings fill the first chamber. When the medium frequency induction furnace is tilted, the molten iron rushes into the second chamber.

6. The method for preparing the metal crusher guard plate according to claim 1, characterized in that, The steel plate is made of the same material as the base material, and the thickness of the steel plate is 0.5~2mm; the surface of the steel plate should be degreased and derusted before use.

7. The method for preparing the metal crusher guard plate according to claim 6, characterized in that, When the steel plate separates the base cavity from the wear-resistant plate cavity, resin sand is inserted into the four sides of the steel plate; after cooling and opening the box, the part of the steel plate that protrudes from the metal crusher guard plate is cut and ground.

8. The method for preparing the metal crusher guard plate according to claim 1, characterized in that, The main components of the salt bath include KNO2, KNO3, NaNO2 and NaNO3, in the following weight ratio: KNO2:KNO3:NaNO2:NaNO3 = 8:4:5:3.

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