Casting method for preventing orange peel defects on the surface of alloy steel castings

Abstract

The present application provides a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings, comprising: taking out a casting model from a solidified sand mold, and performing mold repair and cleaning on the surface of the sand mold; brushing a primer coating on the cleaned surface of the sand mold, wherein the primer coating is a highly permeable alcohol-based zircon powder coating with a Baume degree of 60-65°Bé; brushing a first layer of coating and a second layer of coating on the sand mold, wherein the first layer of coating and the second layer of coating are both alcohol-based zircon powder coatings with a Baume degree of 70-75°Bé, and the total coating thickness is not less than 0.5 mm; brushing a third layer of coating and a fourth layer of coating, wherein the third layer of coating and the fourth layer of coating are both alcohol-based corundum powder coatings with a Baume degree of 65-70°Bé, and the total coating thickness is between 0.6 mm-0.8 mm, wherein the fourth layer of coating is increased or decreased according to the actual thickness of the coating; drying the surface of the coating as a whole, closing the sand mold after brushing the coating, and performing a mold baking treatment, and then casting to obtain a target casting.

Description

Technical Field

[0001] The present application belongs to the technical field of steel casting, and in particular, relates to a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings. Background Art

[0002] When producing medium and large alloy steel castings, the casting materials are generally low alloy steel and high alloy steel, and the materials usually contain alloy elements such as Cr, Ni, Mo, V, W, Nb, etc. When casting, resin sand molding or water glass molding process is generally used, and the surface sand layer uses new silica sand with a silicon dioxide content of ≥98%. After the sand mold is hardened, it is demolded and refractory coating is applied to separate the molten steel from the sand mold surface.

[0003] After heat treatment of such medium and large steel castings by sandblasting or shot peening, the surface of the castings will be covered with orange peel-like spots and dot-like protrusions. The main reasons for such orange peel-like defects are: (1) After the sand mold surface is painted, the paint cannot fill the gaps between the gravel. After the molten steel is poured, the large pressure from the molten steel presses the paint layer partially into the gaps between the gravel, causing pits in the original paint layer. After the molten steel enters the pits, local protrusions are formed; (2) Zircon powder paint is easily decomposed into ZrO2 and SiO2 under high temperature. The decomposed SiO2 reacts with the FeO on the casting surface at high temperature to generate low-melting silicates. When there are a large number of alkali metal elements such as manganese and chromium in the molten steel, the decomposition temperature of zircon powder will be further reduced. After the casting is poured, during the cooling process, the decomposition amount of zircon powder in the coating layer will further increase, and the amount of SiO2 produced will also increase, resulting in an increase in the low-melting reaction product Fe2SiO4, and the integrity of the coating on the sand mold surface will be destroyed. The molten steel will then enter, resulting in orange peel-like defects on the casting surface. The current treatment method is generally to polish the orange peel-like defects on the casting surface through air planing, grinding, etc., but this method will generate huge manufacturing costs and restrict the production efficiency of castings.

[0004] Application Contents

[0005] The present application discloses a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings, which solves the problem that the current method for treating orange peel defects will generate huge manufacturing costs and affect the production efficiency of steel castings.

[0006] The present application discloses a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings, comprising: taking out a casting model from a solidified sand mold, and performing mold repair and cleaning on the surface of the sand mold; brushing a primer coating on the cleaned surface of the sand mold, wherein the primer coating is a highly permeable alcohol-based zircon powder coating with a Baume degree of 60-65°Bé; brushing a first layer of coating and a second layer of coating on the sand mold, wherein the first layer of coating and the second layer of coating are both alcohol-based zircon powder coatings with a Baume degree of 70-75°Bé, and the total coating thickness is not less than 0.5mm; brushing a third layer of coating and a fourth layer of coating, wherein the third layer of coating and the fourth layer of coating are both alcohol-based corundum powder coatings with a Baume degree of 65-70°Bé, and the total coating thickness is between 0.6mm-0.8mm, wherein the fourth layer of coating is increased or decreased according to the actual thickness of the coating.

[0007] In this way, while ensuring that the gaps between the sand and gravel in the sand mold are filled with the highly permeable alcohol-based zircon powder coating, the first and second layers of coating are applied first to form a uniform zircon powder coating, and then the third and fourth layers of coating are applied to form a uniform corundum powder coating. The corundum powder coating isolates the direct contact between the molten steel and the zircon powder coating, avoiding the reaction between the molten steel and the zircon powder coating, so that the surface of the cast alloy steel casting is smooth, and the uneven orange peel-like defects on the surface are completely eliminated.

[0008] Furthermore, the penetration of the primer into the sand mold is not less than 10 mm.

[0009] In this way, the highly permeable alcohol-based zircon powder coating can effectively penetrate into the sand mold and fill the gaps between the gravel, avoiding the situation where the high pressure of the molten steel presses the coating layer into the gaps between the gravel when filling the molten steel, causing pits to appear in the originally completed coating layer, resulting in orange peel defects on the casting surface. At the same time, while ensuring that the penetration of the bottom coating into the sand mold is not less than 10mm, there will be no brushing obstruction in the subsequent brushing operation, affecting the uniformity of the entire coating.

[0010] Furthermore, after the cleaned sand mold surface is coated with the primer, the method further includes: igniting the primer to consume the diluent in the primer. By igniting, the alcohol in the alcohol-based zircon powder coating can be ignited to consume the diluent in the primer, i.e., the alcohol. When the alcohol burns, the water can be evaporated, thereby drying the zircon powder coating.

[0011] Furthermore, the method of brushing the first layer of paint and the second layer of paint on the sand mold includes: after brushing the first layer of paint, igniting the first layer of paint and using natural gas to dry the surface; and brushing the second layer of paint when the first layer of paint after surface drying is slowly cooled to room temperature.

[0012] Furthermore, the brushing directions of the first layer of paint and the second layer of paint are perpendicular, the brushing direction of the second layer of paint and the brushing direction of the third layer of paint are perpendicular, and the brushing directions of the third layer of paint and the fourth layer of paint are perpendicular.

[0013] In this way, the brushing directions of two adjacent layers of paint are made perpendicular to each other. When brushing the next layer of paint, the brushing gaps of the previous layer of paint can be filled, reducing the brushing marks of the upper layer of paint, enhancing the uniformity of each layer of coating, and making the coating smoother.

[0014] Furthermore, after the third and fourth layers of paint are applied by brushing, the method further includes: drying the paint surface, assembling the sand molds, baking the assembled sand molds, and performing pouring.

[0015] In this way, after the coating is applied, a relatively uniform and smooth coating can be formed, and then the coating can be dried to remove the moisture in the coating, and then the box can be assembled, and the sand mold after the box is assembled can be baked, and then the casting process can be carried out, so that the molten steel is introduced into the sand mold, and the surface of the cast alloy steel casting is flat, completely eliminating the uneven orange peel-like defects on the surface. The workload of air planing and grinding is reduced, the production efficiency of the cleaning process is improved, and the production components are greatly reduced.

[0016] The technical effects of this application are:

[0017] The embodiment of the present application discloses a method for preventing orange peel defects from occurring on the surface of alloy steel castings. After the surface of the sand mold is repaired and cleaned, a primer is applied by brushing. The primer is a highly permeable alcohol-based zircon powder paint with a Baume degree of between 60-65°Bé, so as to fill the gaps between the gravel on the surface of the sand mold and facilitate subsequent brushing. Then, a first layer of paint and a second layer of paint are applied by brushing. Both the first layer of paint and the second layer of paint are alcohol-based zircon powder paints. After brushing, a zircon powder coating can be formed, and the total thickness of the coating is not less than 0.5 mm. Then, a third layer of paint and a fourth layer of paint are applied by brushing to form a corundum powder coating, thereby avoiding direct contact between the zircon powder coating and the molten steel, avoiding the reduction of the decomposition temperature of the zircon powder in an alkali metal atmosphere, effectively reducing the decomposition amount of zircon powder during the cooling process of the casting, reducing the reaction between the iron oxide on the surface of the casting and the decomposition products of the zircon powder, and ensuring the integrity of the coating. Afterwards, the fourth layer of coating can be added or reduced according to the actual situation of the sum of the thicknesses of the coatings, thereby avoiding material waste, which leads to increased costs, reducing the workload of air planing and grinding, improving the production efficiency of the cleaning process, and significantly reducing production costs. In other words, the casting method for preventing orange peel defects from occurring on the surface of steel castings made of alloy materials disclosed in the embodiment of the present application effectively prevents orange peel defects and reduces casting costs by applying multiple layers of coatings with different numbers of layers of coatings having different compositions, thereby solving the problem that the current method for dealing with orange peel defects will generate huge manufacturing costs and affect the production efficiency of steel castings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flow chart of a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings;

[0019] Figure 2 It is a schematic flow chart of another casting method for preventing orange peel defects on the surface of alloy steel castings. DETAILED DESCRIPTION

[0020] The specific implementation of the present application is described below with reference to the accompanying drawings.

[0021] Figure 1 The figure is a flow chart of a casting method for preventing the alloy steel material from gradually producing orange peel defects on the surface. Figure 1 As shown, a casting method for preventing orange peel defects from occurring on the surface of alloy steel castings disclosed in an embodiment of the present application comprises the following steps:

[0022] S102: The casting model is taken out from the solidified sand mold, and the surface of the sand mold is repaired and cleaned.

[0023] By trimming and cleaning the surface of the sand mold, excess sand and gravel on the surface of the sand mold are removed to avoid affecting the smoothness of the subsequent brushing operation. It should be noted that the sand mold in the embodiment of the present application is mainly silica sand, with a silicon dioxide content of ≥98%.

[0024] S104: Apply primer to the cleaned sand mold surface. The primer is a highly permeable alcohol-based zircon powder paint with a Baume degree between 60-65°Bé.

[0025] First, apply the primer on the cleaned sand mold. You can choose a highly permeable alcohol-based zircon powder paint with finer aggregate particles. You can apply the paint manually. The alcohol-based zircon powder paint can be an alcohol-based zircon powder paint with a Baume degree of 60-65°Bé. The highly permeable alcohol-based zircon powder paint can fill the gaps between the sand and gravel in contact with the surface of the casting, which is conducive to the subsequent brushing operation. At the same time, it can also effectively prevent the iron oxide on the surface of the casting from penetrating into the sand mold, avoiding the reaction between the silicon dioxide in the sand mold and the iron oxide.

[0026] When the alcohol-based zircon powder coating is less than 60°Bé, the alcohol content in the alcohol-based zircon powder coating is large. When the coating is dried after brushing, the alcohol in the alcohol-based zircon powder coating is ignited, which can easily burn the sand mold, reduce the hardness of the sand mold, and cause the sand mold to be easily damaged. When the alcohol-based zircon powder coating is greater than 65°Bé, the high-permeability alcohol-based zircon powder coating has a long penetration time, the brushing efficiency is not high, and it will cause paint waste.

[0027] S106: Apply the first and second layers of paint to the sand mold. Both the first and second layers of paint are alcohol-based zircon powder paints with a Baume degree of 70-75°Bé, and the total coating thickness is not less than 0.5mm.

[0028] By brushing the alcohol-based zircon powder coating with a Baume degree of 70-75°Bé, a zircon powder coating can be formed to prevent the silicon dioxide in the sand mold from reacting with the iron oxide on the surface of the casting. When the Baume degree of the alcohol-based zircon powder coating is less than 70°Bé, due to the low concentration of the alcohol-based zircon powder coating at this time, a complete coating cannot be formed, and the operator may need to brush it several times to form a complete zircon powder coating. When the Baume degree of the alcohol-based zircon powder coating is greater than 75°Bé, due to the high concentration and strong viscosity of the alcohol-based zircon powder coating at this time, when brushing the first and second layers of coating, brush marks are obvious and the brushing thickness is uneven. After the coating expands due to heat, the coating is prone to cracking and peeling, resulting in the casting molten steel contacting the sand mold surface after being poured into the sand mold, and the iron oxide in the casting reacting with the silicon dioxide. In the case of alcohol-based zircon powder paint with a Baume degree of 73°Bé, the first and second coats of paint can be applied quickly by brush, and a uniform zircon powder coating can be formed by brushing only two coats.

[0029] S108: Apply the third and fourth layers of paint by brush. Both the third and fourth layers of paint are alcohol-based corundum powder paints with a Baume degree of 65-70°Bé. The total coating thickness is between 0.6mm and 0.8mm. The fourth layer of paint is added or reduced according to the actual thickness of the coating.

[0030] After the first and second layers of paint are applied, the third and fourth layers of paint can be applied. The third and fourth layers of paint can be alcohol-based corundum powder paints with a Baume degree of 65-70°Bé. The corundum powder coating can isolate the contact between the zircon powder coating and the molten steel, and avoid direct contact and reaction between the zircon powder coating and the molten steel. When the Baume degree of the alcohol-based corundum powder coating is less than 65°Bé, the corundum powder coating cannot be formed, and multiple applications are required to form the coating. When the Baume degree of the alcohol-based corundum powder coating is greater than 70°Bé, uneven application is likely to occur, and the coating is prone to expansion and peeling at high temperatures. At this time, the total thickness of the applied coating is between 0.6mm-0.8mm. When the total thickness of the coating is less than 0.6mm, the coating thickness is thin, and orange peel defects cannot be avoided, which in turn affects product quality. When the total coating thickness is greater than 0.8 mm, the coating thickness is relatively thick. When applying by brush, the brush is easy to stick to the coating, and thus a uniform coating cannot be formed. At high temperatures, the coating is easy to peel off. In addition, the fourth layer of coating can be added or reduced according to the actual thickness of the coating. After applying the third layer of coating, if the coating thickness meets the requirements, the fourth layer of coating can be reduced, otherwise the fourth layer of coating can be added, thereby avoiding the waste of coating.

[0031] S110: The surface of the coating is dried as a whole, the sand mold coated with the coating is assembled and baked, and then casting is performed to obtain the target casting.

[0032] In this way, after the paint is applied, a relatively uniform and smooth coating can be formed, and then the coating can be dried as a whole to remove the moisture in the paint, and then the box can be assembled, and the sand mold after the box is assembled is baked, and the casting process is performed to allow the molten steel to be introduced into the sand mold to obtain the target casting. At this time, the surface of the alloy steel casting obtained by pouring is flat, and the uneven orange peel-like defects on the surface are completely eliminated. The workload of air planing and grinding is reduced, the production efficiency of the cleaning process is improved, and the production cost is greatly reduced.

[0033] The embodiment of the present application discloses a casting method for preventing orange peel defects on the surface of alloy steel castings. After the sand mold surface is repaired and cleaned, a primer is applied by brushing. The primer is a highly permeable alcohol-based zircon powder paint with a Baume degree of between 60-65°Bé, so as to fill the gaps between the gravel on the surface of the sand mold and facilitate subsequent brushing. Then, a first layer of paint and a second layer of paint are applied by brushing. Both the first layer of paint and the second layer of paint are alcohol-based zircon powder paints. After brushing, a zircon powder coating can be formed, and the total thickness of the coating is not less than 0.5 mm. Then, a third layer of paint and a fourth layer of paint are applied by brushing to form a corundum powder coating, thereby avoiding direct contact between the zircon powder coating and the molten steel, avoiding the reduction of the decomposition temperature of the zircon powder in an alkali metal atmosphere, effectively reducing the decomposition amount of zircon powder during the cooling process of the casting, reducing the reaction between the iron oxide on the surface of the casting and the decomposition products of the zircon powder, and ensuring the integrity of the coating. Afterwards, the fourth layer of coating can be added or reduced according to the actual situation of the sum of the thicknesses of the coatings, thereby avoiding material waste, which leads to increased costs, reducing the workload of air planing and grinding, improving the production efficiency of the cleaning process, and greatly reducing the production components. That is to say, the casting method for preventing orange peel defects from occurring on the surface of steel castings made of alloy materials disclosed in the embodiment of the present application effectively prevents orange peel defects and reduces casting costs by applying multiple layers of coatings with different numbers of layers of coatings of different compositions, thereby solving the problem that the current method of dealing with orange peel defects will generate huge manufacturing costs and affect the production efficiency of steel castings.

[0034] Figure 2 FIG. 1 is a flow chart of another casting method for preventing orange peel defects on the surface of alloy steel castings disclosed in an embodiment of the present application. Figure 2 As shown, the casting method disclosed in the present application for preventing orange peel defects from occurring on the surface of alloy steel castings comprises the following steps:

[0035] S210: taking out the casting model from the solidified sand mold, and performing shaping and cleaning on the surface of the sand mold.

[0036] S220: Apply the primer to the sand mold in sequence. The primer is a highly permeable alcohol-based zircon powder paint with a Baume degree between 60°Bé and 65°Bé.

[0037] S230: Apply 3 to 4 layers of target paint by brushing, each layer of target paint is a mixture of 50% to 60% zircon powder paint and corundum powder paint, the Baume degree of the target paint is between 70°Bé and 75°Bé, and the total thickness of the paint after brushing is between 0.6mm and 0.8mm.

[0038] When the mass fraction of zircon powder coating is 50%-60%, the mass fraction of corundum powder should be 50%-40%

[0039] When the mass fraction of zircon powder coating is 30%

[0040] First apply the primer on the cleaned sand mold. The primer can be a high-permeability alcohol-based zircon powder paint with finer aggregate particles. The high-permeability alcohol-based zircon powder paint can fill the gaps between the gravel in contact with the casting surface, which is helpful for subsequent brushing operations. It can also avoid the reaction between the silica in the sand mold and the iron oxide on the casting surface.

[0041] At this time, the Baume degree of the high-permeability alcohol-based zircon powder is between 60°Bé and 65°Bé. When the alcohol-based zircon powder coating is less than 60°Bé, the alcohol content in the alcohol-based zircon powder coating is large. When the coating is dried after the base coating is applied, the alcohol in the alcohol-based zircon powder coating is ignited, which can easily burn the sand mold, reduce the hardness of the sand mold, and cause the sand mold to be easily damaged. When the alcohol-based zircon powder coating is greater than 65°Bé, it takes a long time for the alcohol-based zircon powder coating to penetrate into the sand mold, resulting in low brushing efficiency of the base coating and waste of coating.

[0042] After the base coating is applied, 3 to 4 layers of target coating are applied. The target coating is obtained by mixing zircon powder coating and corundum powder coating and stirring them evenly. By mixing zircon powder coating and corundum powder coating as the target coating, the mass fraction of zircon powder coating can be effectively reduced, and the decomposition amount of zircon powder under high temperature can be reduced. At the same time, SiO2 produced by the decomposition of zircon powder and FeO on the casting surface, Al2O3 in corundum powder and other components in the coating undergo multi-phase eutectic at high temperature to generate glass phase compounds, which can effectively fill the gaps between zircon powder and corundum powder particles, making the coating layer denser and ensuring the integrity of the coating. At this time, the Baume degree of the target coating is between 70°Bé and 75°Bé. When the Baume degree of the target coating is less than 70°Bé, the concentration of the target coating is low and a complete coating cannot be formed, resulting in the operator having to apply it multiple times to form a complete coating. When the Baume degree of the target coating is greater than 75°Bé, the concentration of the target coating is high and the viscosity is strong. When multiple layers of the target coating are applied, the brush marks are obvious and the brushing thickness is uneven. After the coating expands due to heat, the coating is prone to cracking and peeling, resulting in the silicon dioxide in the sand mold reacting with the iron dioxide in the casting steel liquid after the molten steel is poured into the sand mold.

[0043] After brushing the base coat and 3-4 layers of target coating, the total coating thickness is between 0.6mm-0.8mm. When the total coating thickness is less than 0.6mm, the coating thickness is thin, and the orange peel defect cannot be avoided, which affects the product quality. When the total coating thickness is greater than 0.8mm, the coating thickness is thicker. When brushing, the brush is easy to stick to the coating, and then a uniform coating cannot be formed. At high temperatures, the coating is easy to peel off. Therefore, the operator can increase or decrease the fourth layer of target coating according to the actual total thickness of the coating.

[0044] Furthermore, in the present application, the penetration of the bottom coating into the sand mold is not less than 10 mm. In this way, the highly permeable alcohol-based zircon powder coating can effectively penetrate into the sand mold and fill the gaps between the gravel, avoiding the situation where the large pressure of the molten steel presses the coating layer partially into the gaps between the gravel when filling the molten steel, causing pits to appear locally in the originally completed coating layer, resulting in orange peel defects on the surface of the casting. At the same time, while ensuring that the penetration of the bottom coating into the sand mold is not less than 10 mm, there will be no brushing obstruction in the subsequent brushing operation, affecting the uniformity of the entire coating.

[0045] In the present application, after the cleaned sand mold surface is coated with the primer, the method further comprises the following steps: igniting the primer to consume the diluent in the primer. By igniting, the alcohol in the alcohol-based zircon powder coating can be ignited to consume the diluent in the primer, i.e., the alcohol. When the alcohol burns, the water can be evaporated, thereby drying the zircon powder coating.

[0046] In addition, in the present application, applying the first layer of coating and the second layer of coating to the sand mold may include the following steps:

[0047] Step 1: After applying the first coat of paint, ignite the first coat of paint and use natural gas to dry it on the surface.

[0048] Step 2: After the first layer of paint is dried, slowly cool down to room temperature, apply the second layer of paint. In this way, after the first layer of paint is dried with natural gas, the moisture in the first layer of paint can be removed. After the first layer of paint is dried, slowly cool down to room temperature before applying the second layer of paint, so as to ensure the strength of the paint layer.

[0049] In one possible implementation, the brushing directions of the first and second layers of paint are perpendicular, the brushing directions of the second and third layers of paint are perpendicular, and the brushing directions of the third and fourth layers of paint are perpendicular. In this way, the brushing directions of two adjacent layers of paint are perpendicular to each other, and when brushing the next layer of paint, the brushing gap of the previous layer of paint can be filled, reducing the brushing marks of the previous layer of paint, enhancing the uniformity of each layer of paint, and making the coating smoother.

[0050] In one possible implementation, after applying the third and fourth layers of paint, the method further comprises the following steps:

[0051] Step 1: Allow the paint surface to dry and assemble the sand mold.

[0052] Step 2: Bake the assembled sand mold and then pour it.

[0053] In this way, after the coating is applied, a relatively uniform and smooth coating can be formed, and then the coating can be dried to remove the moisture in the coating, and then the box can be assembled, and the sand mold after the box is assembled can be baked, and then the casting process can be carried out, so that the molten steel is introduced into the sand mold, and the surface of the cast alloy steel casting is flat, completely eliminating the uneven orange peel-like defects on the surface. The workload of air planing and grinding is reduced, the production efficiency of the cleaning process is improved, and the production cost is greatly reduced.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A casting method for preventing orange peel defects on the surface of alloy steel castings, characterized in that: include: The casting model is taken out from the solidified sand mold, and the surface of the sand mold is repaired and cleaned; Applying a primer to the cleaned sand mold surface, wherein the primer is a highly permeable alcohol-based zircon powder paint with a Baume degree of 60-65°Bé; Apply the first and second layers of paint to the sand mold. Both the first and second layers of paint are alcohol-based zircon powder paints with a Baume degree of 70-75°Bé, and the total coating thickness is not less than 0.5mm; Applying a third layer of paint and a fourth layer of paint by brush, wherein the third layer of paint and the fourth layer of paint are both alcohol-based corundum powder paints with a Baume degree of 65-70°Bé, and the total thickness of the coatings is between 0.6mm and 0.8mm, wherein the fourth layer of paint is added or reduced according to the actual thickness of the coatings; The surface of the coating is dried as a whole, the sand mold coated with the coating is assembled and baked, and then poured to obtain the target casting; The brushing directions of the first and second layers of paint are perpendicular to each other, the brushing direction of the second and third layers of paint are perpendicular to each other, and the brushing directions of the third and fourth layers of paint are perpendicular to each other.

2. A casting method for preventing orange peel defects from occurring on the surface of alloy steel castings, characterized in that: include: The casting model is taken out from the solidified sand mold, and the surface of the sand mold is repaired and cleaned; Apply a primer to the cleaned sand mold, wherein the primer is a highly permeable alcohol-based zircon powder paint with a Baume degree between 60 and 65°Bé; Apply 3 to 4 layers of target paint by brushing, each layer of target paint is a mixture of 50% to 60% zircon powder paint and corundum powder paint, the Baume degree of the target paint is between 70°Bé and 75°Bé, and the total thickness of the paint applied by brushing is between 0.6mm and 0.8mm; The surface of the coating is dried as a whole, the sand mold coated with the coating is assembled and baked, and then poured to obtain the target casting; The second layer of target paint is applied in a direction perpendicular to the first layer of target paint, the third layer of target paint is applied in a direction perpendicular to the second layer of target paint, and the fourth layer of target paint is applied in a direction perpendicular to the third layer of target paint.

3. The casting method according to claim 1 or 2, characterized in that: Before the casting model is taken out from the solidified sand mold and the sand mold surface is repaired and cleaned, it also includes: Place the casting model in the sand box, use flowing sand to shape it, and place chromium ore sand or chromium sand chilled iron with a thickness of 30~50mm in the thickest area of ​​the casting wall.

4. The casting method according to claim 1 or 2, characterized in that: The penetration of the primer into the sand mold is not less than 10 mm.

5. The casting method according to claim 1 or 2, characterized in that: After the primer is applied to the surface of the sand mold, the method further comprises: The ignition ignites the primer and consumes the diluent in the primer.

6. The casting method according to claim 1, characterized in that: The method of brushing the first layer of paint and the second layer of paint on the sand mold comprises: After the first layer of paint is applied by brush, the first layer of paint is ignited and surface dried using natural gas; When the first layer of paint is slowly cooled to room temperature after being surface-dried, the second layer of paint is applied by brush.

7. The casting method according to claim 2, characterized in that: The method of applying 3 to 4 layers of target coating by brushing comprises: Apply the first coat of target paint by brush; The first layer of target paint is surface dried, and when the first layer of target paint is slowly cooled to room temperature, a second layer of target paint is applied by brush; The second layer of target paint is surface dried, and when the second layer of target paint is slowly cooled to room temperature, a third layer of target paint is applied by brush; The third layer of target paint is surface dried, and a fourth layer of target paint is applied by brushing when the third layer of target paint is slowly cooled to room temperature; Wherein, the fourth layer of target coating is increased or decreased according to the total coating thickness.

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