A ladle for casting high alloy heat resistant steel castings and a method of lining the same

Abstract

The application belongs to the technical field of alloy smelting equipment, and particularly discloses a ladle for casting high-alloy heat-resistant steel castings and a repairing method thereof. The bottom layer, the intermediate layer and the surface coating are built in layers by using refractory materials with different components. The surface coating has very low content of phosphorus pentoxide, and the temperature resistance of the surface coating is close to the tapping temperature. The surface coating can quickly form a glaze layer, and has a certain anti-erosion property. The formed glaze layer effectively prevents the molten steel from being eroded, and prevents the intermediate layer and the bottom layer from returning phosphorus. The surface coating, the intermediate layer and the bottom layer are built in layers, so that the crack penetration effect is effectively eliminated, and the safety of the ladle is improved. The ladle for casting high-alloy heat-resistant steel castings has low cost, high safety, and can effectively prevent phosphorus from increasing during the tapping and pouring processes, and has great significance. In addition, the construction period is short, the repair is convenient, the ladle basically does not increase phosphorus during use, the refractory layer is thin in thickness, the ladle has large capacity, and the production efficiency can be improved.

Description

Technical Field

[0001] This invention belongs to the technical field of alloy smelting equipment, and specifically discloses a ladle for casting high alloy heat-resistant steel castings and its construction method. Background Technology

[0002] A ladle, or simply ladle, is a crucial piece of equipment made of refractory materials, used for holding and pouring molten steel. It is also a key container for ladle refining of molten steel (fluid metal) outside the furnace (and now also has metallurgical functions). As a critical container in steelmaking, the stable operation of the ladle directly affects the efficiency of continuous operations and the safety of on-site personnel. High-alloy heat-resistant steel castings are widely used in applications with operating temperatures exceeding 700℃, often using medium-frequency induction furnaces for melting. Melting temperatures exceed 1600℃, with some steel grades reaching 1750℃. Tapping temperatures are generally between 1650-1720℃, placing extremely high demands on the refractory materials used in the ladle. Currently, the industry commonly uses corundum materials with alumina as the main component to construct the refractory layer of the ladle, achieving a refractory temperature of up to 1800℃. To improve the plasticity of the refractory layer, a certain amount of water and binder needs to be added; phosphorus pentoxide is a commonly used binder. During the tapping and casting process, under high temperature, some phosphorus elements in the binder enter the molten steel, causing the phosphorus content of the molten steel to rise continuously. The standards for casting high alloy heat-resistant steel (ISO 11973, GB / T 8492, etc.) have strict requirements for the phosphorus content in steel: P≤0.04%. At present, there is no effective dephosphorization method, and only the dilution method can be used, that is, adding phosphorus-free or low-phosphorus metal materials into the furnace to neutralize it. Summary of the Invention

[0003] To address the problems in the background art, this invention discloses a ladle for casting high-alloy heat-resistant steel castings and its construction method. The ladle includes a layered construction of a bottom layer, an intermediate layer, and a surface coating. The surface coating has a temperature resistance close to the tapping temperature, forms a glaze layer quickly, and has a certain degree of erosion resistance. The formed glaze layer effectively prevents molten steel from corroding the steel, while also preventing phosphorus return in the intermediate and bottom layers. This effectively prevents phosphorus increase during tapping and casting, and ensures high safety.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A ladle for casting high-alloy heat-resistant steel castings includes a base layer constructed in contact with the inner wall steel plate of the ladle, and an intermediate layer and a surface coating layer constructed sequentially within the base layer, wherein...

[0006] The refractory material I used for constructing the base layer comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 3-5%, Cr2O3 0.8-1.2%, with the balance being water;

[0007] The refractory material II used for constructing the intermediate layer comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 1.5-2.2%, Cr2O3 0.8-1.2%, with the balance being water;

[0008] The refractory material III used for constructing the surface coating comprises the following components by weight percentage: Al2O3 80%-85%, SiO2 10.5%-14%, P2O5 0.2%-0.5%, MgO 3%-5%, with the balance being water.

[0009] Furthermore, in the ladle for casting high-alloy heat-resistant steel castings, the refractory material I used for the bottom layer has a uniform particle size distribution, with the largest particle diameter in the composition being equal to 5 mm, and particles smaller than 200 mesh accounting for 35%;

[0010] The refractory material II used to construct the intermediate layer has a uniform particle size distribution, with the largest particle diameter in the composition being 3 mm, and particles smaller than 200 mesh accounting for 40%.

[0011] The refractory material III used for constructing the surface coating has a uniform particle size distribution, with the largest particle diameter in the component being 0.5 mm, and fine powder below 200 mesh accounting for 45%.

[0012] Furthermore, the ladle for casting the high-alloy heat-resistant steel casting has a bottom layer thickness of 4-6 cm, an intermediate layer thickness of 3-5 cm, and a surface coating thickness of 1-2 cm.

[0013] A method for constructing a ladle for casting high-alloy heat-resistant steel castings, the method comprising the following steps: first, weighing the raw materials of refractory material I, refractory material II, and refractory material III according to a certain proportion; mixing the components of refractory material I, refractory material II, and refractory material III evenly according to a certain proportion to obtain refractory material I, refractory material II, and refractory material III respectively; uniformly applying a certain thickness of refractory material I to the inner wall steel plate of the ladle, pounding it until dense, and then baking it to form a solid bottom layer; after baking, allowing it to be placed at room temperature naturally; uniformly applying a certain thickness of refractory material II to the inner wall of the bottom layer, pounding it until dense, and then baking it to form a solid intermediate layer; after baking, allowing it to be placed at room temperature naturally; uniformly applying a certain thickness of refractory material III to the inner wall of the intermediate layer; and after baking, forming a smooth and delicate surface coating, finally obtaining a ladle for casting high-alloy heat-resistant steel castings constructed in layers.

[0014] Furthermore, the method for constructing the ladle for casting high-alloy heat-resistant steel castings involves a baking temperature of 600℃ and a baking time of 15-60 minutes.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] This invention relates to a ladle for casting high-alloy heat-resistant steel parts. It employs refractory materials of different compositions to construct a layered base, intermediate layer, and surface coating. The surface coating has an extremely low phosphorus pentoxide content and its temperature resistance is close to the tapping temperature, allowing for rapid glaze formation. It also possesses a certain degree of erosion resistance. The formed glaze effectively prevents molten steel corrosion and inhibits phosphorus re-entry into the intermediate and base layers. The layered construction of the surface coating, intermediate layer, and base layer effectively eliminates the crack penetration effect, improving the ladle's safety and service life. This invention provides a low-cost, high-safety ladle for casting high-alloy heat-resistant steel parts, effectively preventing phosphorus accumulation during tapping and pouring, which is of great significance.

[0017] The present invention provides a method for constructing a ladle for casting high-alloy heat-resistant steel castings. This method has a short construction period, is easy to repair, and the ladle does not increase phosphorus content during use. Furthermore, the refractory layer is thin, and the ladle has a large capacity, which can improve production efficiency. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a three-dimensional structural diagram of the ladle used for casting high-alloy heat-resistant steel castings according to the present invention;

[0020] In the image above: 1-bottom layer; 2-intermediate layer; 3-surface coating. Detailed Implementation

[0021] To better understand the present invention, the following embodiments further illustrate the content of the invention, but the scope of protection of the present invention is not limited to the following embodiments. Numerous specific details are set forth in the following description to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without one or more of these details.

[0022] Combined with appendix Figure 1 The invention describes in detail the ladle for casting high-alloy heat-resistant steel castings, comprising a bottom layer 1 constructed in contact with the inner wall steel plate of the ladle, and an intermediate layer 2 and a surface coating layer 3 constructed sequentially within the bottom layer 1.

[0023] The refractory material I used to construct the bottom layer 1 comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 3-5%, Cr2O3 0.8-1.2%, with the balance being water;

[0024] The refractory material II used to construct intermediate layer 2 comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 1.5-2.2%, Cr2O3 0.8-1.2%, with the balance being water;

[0025] The refractory material Ⅲ of the surface coating 3 comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 10.5%-14%, P2O5 0.2-0.5%, MgO 3-5%, with the balance being water.

[0026] The ladle for casting high-alloy heat-resistant steel parts has the following characteristics: the maximum particle diameter of refractory material I in the bottom layer 1 is 5 mm, and 35% of the particles are below 200 mesh; the maximum particle diameter of refractory material II in the intermediate layer 2 is 3 mm, and 40% of the particles are below 200 mesh; the maximum particle diameter of refractory material III in the surface coating layer 3 is 0.5 mm, and 45% of the fine powder is below 200 mesh. It should be noted that the particle size distribution of refractory material I, refractory material II, and refractory material III is uniform, and the particle size in the refractory material components has a significant impact on the quality of the ladle for casting high-alloy heat-resistant steel parts.

[0027] The ladle for casting high-alloy heat-resistant steel castings, taking a ton ladle as an example, has a bottom layer 1 with a thickness of 4-6 cm, a middle layer 2 with a thickness of 3-5 cm, and a surface coating 3 with a thickness of 1-2 cm.

[0028] A method for constructing a ladle for casting high-alloy heat-resistant steel castings is disclosed. This method comprises the following steps: First, weigh out the raw materials of refractory material I, refractory material II, and refractory material III according to the specified proportions. Mix these components evenly to ensure uniform particle size distribution, thus obtaining refractory material I, refractory material II, and refractory material III respectively. Apply a 4-6 cm thick layer of refractory material I evenly to the inner wall of the ladle, pound it until compacted, and then bake it at 600℃ for approximately 60 minutes in a baking equipment to form a solid bottom layer 1. After baking, allow it to cool to room temperature naturally. Then, apply a 3-5 cm thick layer of refractory material II evenly to the inner wall of the bottom layer 1, pound it until compacted, and then bake it at 600℃ for approximately 45 minutes in a baking equipment to form a solid bottom layer 1. After baking the intermediate layer 2, allow it to cool to room temperature. Then, apply a 1-2 cm thick layer of refractory material III evenly to the inner wall of the intermediate layer 2. After application, bake at 600℃ for about 15 minutes to form a smooth and delicate surface coating 3. This results in a ladle with a layered construction of high-alloy heat-resistant steel castings. The ladle can be used immediately after construction. The surface coating 3 of the ladle has a temperature resistance close to the tapping temperature, allowing for rapid glazing and a certain degree of erosion resistance. The glaze effectively prevents molten steel corrosion and prevents phosphorus return in the intermediate layer 2 and bottom layer 1. The layered construction of surface coating 3, intermediate layer 2, and bottom layer 1 effectively prevents crack penetration and improves the safety of the ladle. The initial construction of a new ladle with three layers takes about 4-5 hours (excluding baking time), resulting in low cost, high safety, short construction period, and minimal phosphorus increase during use. The thin refractory layer allows for a large ladle capacity, improving production efficiency. Furthermore, the bottom layer 1 of the ladle is a permanent layer that will not be damaged and generally does not require removal. When the ladle needs to be repaired after a period of use, the surface coating 3 is completely removed, and the slurry slag falls off. The intermediate layer 2 is repaired with the customized refractory material II, mainly repairing the pits at the impact point of the steel tapping (mainly the bottom of the ladle), the gate, and the nozzle. After the repair is completed, the surface coating 1 is evenly applied again to the inner wall of the intermediate layer 2 with refractory material III, and then baked and dried before being put back into use. The ladle repair can be completed in 1 hour (excluding baking time).

[0029] Example 1 of building a mound:

[0030] 1. Weigh the following components by weight percentage according to the following proportions: 83.5% Al2O3, 10.2% SiO2, 4% P2O5, 0.95% Cr2O3 and 1.35% water, mix them evenly to obtain refractory material I. Apply refractory material I evenly to the bottom and inner surface of the ladle, and then pound it to ensure compaction. The thickness of the base layer is 5 cm. After the construction is completed, use a natural gas ladle baker to bake the base layer at a temperature of 600℃ for about 60 minutes. After the base layer is baked, let it be placed at room temperature naturally.

[0031] 2. Weigh the following components by weight percentage according to the following proportions: 83.8% Al2O3, 12.8% SiO2, 2.1% P2O5, 0.82% Cr2O3 and 0.98% water, mix them evenly to obtain refractory material II. Apply intermediate layer refractory material II evenly to the inner surface of the bottom layer, and then pound it to ensure compaction. The thickness of the intermediate layer is 3.8 cm. After construction, use a natural gas baking oven to bake the bottom layer and intermediate layer together at a temperature of 600℃ for about 45 minutes. After baking, let it stand naturally to room temperature.

[0032] 3. Weigh the following components by weight percentage according to the following proportions: 82% Al2O3, 13.4% SiO2, 0.45% P2O5, 3.7% MgO and 0.45% water. Mix them evenly to obtain refractory material III. Apply refractory material III to the inner surface of the intermediate layer by coating or brushing, with a thickness of 1 cm. After the application is completed, use a natural gas ladle baker to bake the bottom layer, intermediate layer and surface coating layer together at a temperature of 600℃ for about 15 minutes. After baking, the ladle can be used immediately.

[0033] Repair bag example:

[0034] 1. Remove the entire surface coating, and the slurry residue will fall off with it;

[0035] 2. Use customized refractory material II to repair the pits and other missing parts of the inner wall, fill and flatten them, and then re-coat the surface. Apply refractory material III to the inner surface of the intermediate layer by coating or brushing, with a thickness of 1 cm. After completion, bake the construction layer directly at 600℃ for 30 minutes. It can be used immediately after construction.

[0036] Example 2 of building a mound:

[0037] 1. Weigh the following components by weight percentage according to the following proportions: 80% Al2O3, 15% SiO2, 3% P2O5, 1.2% Cr2O3 and 0.8% water, mix them evenly to obtain refractory material I. Apply refractory material I evenly to the bottom and inner surface of the ladle, and then pound it to ensure compaction. The thickness of the base layer is 5 cm. After the construction is completed, use a natural gas ladle baker to bake the base layer at a temperature of 600℃ for about 60 minutes. After the base layer is baked, let it be placed at room temperature naturally.

[0038] 2. Weigh the following components by weight percentage according to the following proportions: 80% Al2O3, 15% SiO2, 2.2% P2O5, 1.2% Cr2O3 and 1.6% water, mix them evenly to obtain refractory material II. Apply intermediate layer refractory material II evenly to the inner surface of the bottom layer, and then pound it to ensure compaction. The thickness of the intermediate layer is 3.8 cm. After the construction is completed, use a natural gas baking oven to bake the bottom layer and intermediate layer together at a temperature of 600℃ for about 45 minutes. After baking, let it stand naturally to room temperature.

[0039] 3. Weigh the following components by weight percentage according to the following proportions: 80% Al2O3, 14% SiO2, 0.5% P2O5, 5% MgO and 0.5% water, mix them evenly to obtain refractory material III. Apply refractory material III to the inner surface of the intermediate layer by coating or brushing, with a thickness of 1 cm. After the application is completed, use a natural gas ladle baker to bake the bottom layer, intermediate layer and surface coating layer together at a temperature of 600℃ for about 15 minutes. After baking, the ladle can be used immediately.

[0040] Example 3 of building a mound:

[0041] 1. Weigh the following components by weight percentage according to the following proportions: 87% Al2O3, 8% SiO2, 4% P2O5, 0.8% Cr2O3 and 0.2% water, mix them evenly to obtain refractory material I. Apply refractory material I evenly to the bottom and inner surface of the ladle, and then pound it to ensure compaction. The thickness of the base layer is 5 cm. After the construction is completed, use a natural gas ladle baker to bake the base layer at a temperature of 600℃ for about 60 minutes. After the base layer is baked, let it be placed at room temperature.

[0042] 2. Weigh the following components by weight percentage according to the following proportions: 87% Al2O3, 8.6% SiO2, 1.5% P2O5, 1.2% Cr2O3 and 1.7% water, mix them evenly to obtain refractory material II. Apply intermediate layer refractory material II evenly to the inner surface of the bottom layer, and then pound it to ensure compaction. The thickness of the intermediate layer is 3.8 cm. After construction, use a natural gas baking oven to bake the bottom layer and intermediate layer together at a temperature of 600℃ for about 45 minutes. After baking, let it stand naturally to room temperature.

[0043] 3. Weigh the following components by weight percentage: 85% Al2O3, 10.5% SiO2, 0.45% P2O5, 3% MgO and 1.05% water, mix them evenly to obtain refractory material III. Apply refractory material III to the inner surface of the intermediate layer by coating or brushing, with a thickness of 1 cm. After the application is completed, use a natural gas ladle baker to bake the bottom layer, intermediate layer and surface coating layer together at a temperature of 600℃ for about 15 minutes. After baking, the ladle can be used immediately.

[0044] Taking a 950-1000KG steel ladle as an example, the service life of the steel ladles constructed in examples one, two, and three, as well as the existing steel ladles, was tracked. The specific details are shown in Table 1 below. The existing steel ladle consists of two layers: an outer layer is a 12cm thick high-temperature cement-cast integral layer, and an inner layer is a 3-4cm thick plastic refractory material containing P2O5. The P2O5 content in the plastic refractory material of the inner layer of the existing steel ladle is 6-8%, and the construction time for the existing steel ladle construction is 5-6 days.

[0045]

[0046] Table 1. Steel Ladle Service Life Tracking Table

[0047] According to the data in Table 1, existing steel ladles require repair on average after 22.6 uses. Ladles constructed using the method for constructing high-alloy heat-resistant steel castings according to this invention require repair only after an average of 30 uses, resulting in higher safety and a longer service life. Furthermore, when repair is needed using the method for constructing high-alloy heat-resistant steel castings according to this invention, only the surface coating needs to be completely removed, and the slurry will fall off. Customized refractory material II is used to repair any pits or missing parts on the inner wall. After filling and smoothing, the surface coating is reconstructed. Refractory material III is applied or brushed onto the inner surface of the intermediate layer to a thickness of 1 cm. After completion, the construction layer is directly baked at 600℃ for 30 minutes. The ladle can be used immediately after construction.

[0048] The changes in phosphorus content in molten steel before and after transfer were investigated using different ladles: molten steel was transferred using existing ladles and ladles constructed in Examples 1, 2, and 3. The phosphorus content in the molten steel was measured before tapping and after transfer using the ladles. Two samples were taken for each measurement. The specific data on phosphorus content in molten steel before and after transfer using existing ladles are shown in Table 2 below. The specific data on phosphorus content in molten steel before and after transfer using ladles constructed in Examples 1, 2, and 3 are shown in Table 3 below.

[0049] Table 2

[0050]

[0051] As shown in Table 2, the average phosphorus content in the molten steel increased by 0.0052% before and after the transfer of molten steel from the existing ladle.

[0052] Table 3

[0053]

[0054] It should be noted that: the data in Table 3, numbers 1-4, are the specific data on the phosphorus content in the molten steel before and after the transfer of molten steel using the ladle constructed in Example 1; the data in numbers 5-8 are the specific data on the phosphorus content in the molten steel before and after the transfer of molten steel using the ladle constructed in Example 2; and the data in numbers 9-12 are the specific data on the phosphorus content in the molten steel before and after the transfer of molten steel using the ladle constructed in Example 3. As can be seen from the data in Table 3, the average increase in phosphorus content in the molten steel before and after the transfer of molten steel using the ladles constructed in Examples 1, 2, and 3 is 0.001%, which is significantly lower than the average increase in phosphorus content in the molten steel before and after the transfer of molten steel using existing ladles. The ladles constructed using the ladle construction method of this invention for casting high-alloy heat-resistant steel castings have a short construction period, are easy to repair, show virtually no phosphorus increase during use, have a thin refractory layer, and a large ladle capacity, thus improving production efficiency.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A ladle for casting high-alloy heat-resistant steel castings, characterized in that, This includes the base layer constructed in contact with the steel plate of the ladle's inner wall, and the intermediate layer and surface coating constructed sequentially within the base layer. The refractory material I used for constructing the base layer comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 3-5%, Cr2O3 0.8-1.2%, with the balance being water; The refractory material II used for constructing the intermediate layer comprises the following components by weight percentage: Al2O3 80%-87%, SiO2 8%-15%, P2O5 1.5-2.2%, Cr2O3 0.8-1.2%, with the balance being water; The refractory material III used for constructing the surface coating comprises the following components by weight percentage: Al2O3 80%-85%, SiO2 10.5%-14%, P2O5 0.2%-0.5%, MgO 3%-5%, with the balance being water.

2. The ladle for casting high-alloy heat-resistant steel castings according to claim 1, characterized in that, The maximum particle diameter of the components of refractory material I used to construct the base layer is 5 mm, and particles smaller than 200 mesh account for 35%; The maximum particle diameter of the components of refractory material II used to construct the intermediate layer is 3 mm, and particles smaller than 200 mesh account for 40%; The maximum particle diameter of the components of refractory material III used for constructing the surface coating is 0.5 mm, and the proportion of fine powder below 200 mesh is 45%.

3. The ladle for casting high-alloy heat-resistant steel castings according to claim 2, characterized in that, The bottom layer is 4-6 cm thick, the middle layer is 3-5 cm thick, and the surface coating is 1-2 cm thick.

4. A method for constructing a ladle for casting high-alloy heat-resistant steel castings, characterized in that, This construction method is used to construct a ladle for casting high-alloy heat-resistant steel castings as described in any one of claims 1-3. The construction method includes the following steps: First, weigh out the components of refractory material I, refractory material II, and refractory material III according to the proportions and mix them evenly to obtain refractory material I, refractory material II, and refractory material III. Then, evenly coat a certain thickness of refractory material I onto the inner wall steel plate of the ladle, pound it until dense, and bake it to form a solid bottom layer. After baking, let it stand naturally at room temperature. Then, evenly coat a certain thickness of refractory material II onto the inner wall of the bottom layer, pound it until dense, and bake it to form a solid middle layer. After baking, let it stand naturally at room temperature. Then, evenly coat a certain thickness of refractory material III onto the inner wall of the middle layer. After coating, bake it to form a smooth and delicate surface coating. Finally, a ladle for casting high-alloy heat-resistant steel castings with layered construction is obtained.

5. The method for constructing a ladle for casting high-alloy heat-resistant steel castings according to claim 4, characterized in that, The baking temperature is 600℃, and the baking time is 15-60 minutes.

Images