Steel billet anti-oxidation and anti-decarburization coating and preparation method and use method thereof

Abstract

The invention relates to a steel billet anti-oxidation and anti-decarburization coating as well as a preparation method and a use method thereof, and belongs to the technical field of metal protective coatings. In order to solve the problems that an existing steel billet protective coating is not strong in binding force with the surface of a steel billet and is prone to cracking and falling off at high temperature, the steel billet anti-oxidation and anti-decarburization coating is provided and comprises a high-temperature-resistant coating, a binding agent, a solvent and an additive, the high-temperature-resistant coating is kaolin, the binding agent is siliceous sol, and the solvent is water or ethyl alcohol. The additive is a composition of anhydrous sodium carbonate and carbon powder or a composition of anhydrous sodium carbonate and graphite powder. The steel billet surface anti-oxidation and anti-decarburization coating provided by the invention has good oxidation resistance and anti-decarburization performance, the coating is firmly combined with the surface of a steel billet and is kept stable at a high temperature of a heating furnace, and the protection quality of the steel billet under a high-temperature heating condition is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of metal protective coating technology, and particularly relates to an anti-oxidation and anti-decarburization coating for steel billets, its preparation method and application method. Background Technology

[0002] During the high-temperature heating process of steel billets at 1100~1300℃, their surface undergoes chemical reactions with oxygen, water vapor, carbon dioxide, and other substances in the furnace gas, leading to frequent oxidation and decarburization. The oxidation reaction forms a multi-layered iron oxide scale, mainly composed of FeO, Fe3O4, and Fe2O3, with a thickness of 1~3 mm. This scale has a strong bond with the billet matrix and is difficult to completely remove. Simultaneously, the decarburization reaction causes carbon elements on the steel surface to combine with hydrogen or oxygen to generate gases such as CH4 and CO, which escape, creating a carbon concentration gradient and resulting in pure ferrite or network ferrite structures on the surface. These two types of defects significantly reduce the surface quality of the rolled steel and weaken its strength, hardness, and fatigue life due to surface carbon loss, ultimately affecting the material's service performance.

[0003] While current protective coatings for steel billets can partially alleviate oxidation and decarburization problems, they still suffer from poor protective effects, weak adhesion between the coating and the billet surface, and susceptibility to cracking and peeling at high temperatures. These issues fail to meet the protective requirements of steel billets in complex high-temperature environments. Therefore, developing a highly efficient and stable anti-oxidation and anti-decarburization spray coating for steel billets is of significant practical importance. Summary of the Invention

[0004] To address the problem that existing protective coatings for steel billets have weak adhesion to the billet surface and are prone to cracking and peeling at high temperatures, this invention provides an anti-oxidation and anti-decarburization coating for steel billets, along with its preparation and application methods.

[0005] The technical solution of the present invention:

[0006] A steel billet anti-oxidation and anti-decarburization coating comprises the following components in parts by weight:

[0007] The high-temperature resistant coating comprises 40-50 parts, a binder comprises 10-20 parts, a solvent comprises 20 parts, and an additive comprises 10 parts. The high-temperature resistant coating is kaolin, the binder is silica sol, the solvent is water or ethanol, and the additive is a combination of anhydrous sodium carbonate and carbon powder, or a combination of anhydrous sodium carbonate and graphite powder.

[0008] Furthermore, the weight ratio of anhydrous sodium carbonate to carbon powder is 1:0.1~10, and the weight ratio of anhydrous sodium carbonate to graphite powder is 1:0.1~10.

[0009] A method for preparing an anti-oxidation and anti-decarburization coating for steel billets includes the following steps:

[0010] Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for a certain period of time to ensure that the solvent and adhesive are fully mixed.

[0011] Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from forming in the solvent. Stir for a certain period of time after pouring.

[0012] Step 3: Pour the additive into the container where the stirred solvent and coating are mixed, and stir continuously and evenly. After mixing evenly, let it stand for a certain period of time to obtain the steel billet anti-oxidation and anti-decarburization coating.

[0013] Furthermore, the stirring time in step one is 30-60 seconds.

[0014] Furthermore, the stirring time in step two is 10-15 minutes.

[0015] Furthermore, the stirring time in step three is 10-15 minutes, and the settling time is 5-10 minutes.

[0016] A method for using an anti-oxidation and anti-decarburization coating for steel billets involves loading the uniformly stirred and allowed to stand into a spraying machine to spray the coating onto the surface of the steel billet, and then directly placing the coated steel billet into a high-temperature furnace.

[0017] Furthermore, if the anti-oxidation and anti-decarburization coating on the steel billet is left to stand for more than 10 minutes before application, it needs to be stirred again before use.

[0018] Furthermore, the billet temperature should be ≤50℃ during spraying.

[0019] Furthermore, the thickness of the coating obtained by spraying is 0.1~0.2mm.

[0020] The beneficial effects of this invention are:

[0021] This invention provides an anti-oxidation and anti-decarburization coating for steel billet surfaces. The coating has good anti-oxidation and anti-decarburization properties, and the coating is firmly bonded to the surface of the steel billet. It remains stable at high temperatures in the heating furnace, effectively improving the protection quality of the steel billet under high-temperature heating conditions. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0023] Example 1

[0024] This embodiment provides a steel billet anti-oxidation and anti-decarburization coating, comprising the following components in parts by weight:

[0025] The high-temperature resistant coating consists of 40 parts kaolin, 20 parts silica sol as a binder, 20 parts ethanol as a solvent, 5 parts anhydrous sodium carbonate, and 5 parts carbon powder.

[0026] The preparation method of the anti-oxidation and anti-decarburization coating for steel billets in this embodiment includes the following steps:

[0027] Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for 30 seconds to ensure that the solvent and adhesive are fully mixed.

[0028] Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from clumping in the solvent. Stir for 10 minutes after pouring completely.

[0029] Step 3: Pour the additive into the container where the solvent and coating are mixed, and stir continuously and evenly for 10 minutes. After mixing evenly, let it stand for 5 minutes to obtain the anti-oxidation and anti-decarburization coating for steel billets.

[0030] The method of using the anti-oxidation and anti-decarburization coating for steel billets in this embodiment is to quickly load the uniformly stirred and allowed to stand into the spraying machine and spray it onto the surface of 100CrMnSi6-4 bearing steel billets. The temperature of the steel billets during spraying is ≤50℃. One layer is sprayed, and the thickness of the resulting coating is 0.1~0.2mm. After the steel billets are coated, they are directly put into the high-temperature furnace.

[0031] The high-temperature furnace temperature is ≤850℃, the maximum heating temperature is 1180-1270℃, and the total heating time is 450min.

[0032] Example 2

[0033] This embodiment provides a steel billet anti-oxidation and anti-decarburization coating, comprising the following components in parts by weight:

[0034] The high-temperature resistant coating consists of 50 parts kaolin, 10 parts silica sol as a binder, 20 parts ethanol as a solvent, 8 parts anhydrous sodium carbonate, and 2 parts carbon powder.

[0035] The preparation method of the anti-oxidation and anti-decarburization coating for steel billets in this embodiment includes the following steps:

[0036] Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for 30 seconds to ensure that the solvent and adhesive are fully mixed.

[0037] Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from clumping in the solvent. Stir for 10 minutes after pouring completely.

[0038] Step 3: Pour the additive into the container where the solvent and coating are mixed, and stir continuously and evenly for 10 minutes. After mixing evenly, let it stand for 5 minutes to obtain the anti-oxidation and anti-decarburization coating for steel billets.

[0039] The method of using the anti-oxidation and anti-decarburization coating for steel billets in this embodiment is to quickly load the uniformly stirred and allowed to stand into the spraying machine and spray it onto the surface of 100CrMnSi6-4 bearing steel billets. The temperature of the steel billets during spraying is ≤50℃. One layer is sprayed, and the thickness of the resulting coating is 0.1~0.2mm. After the steel billets are coated, they are directly put into the high-temperature furnace.

[0040] The high-temperature furnace temperature is ≤850℃, the maximum heating temperature is 1180-1270℃, and the total heating time is 450min.

[0041] Example 3

[0042] This embodiment provides a steel billet anti-oxidation and anti-decarburization coating, comprising the following components in parts by weight:

[0043] The high-temperature resistant coating consists of 45 parts kaolin, 15 parts silica sol as a binder, 20 parts ethanol as a solvent, 3 parts anhydrous sodium carbonate, and 7 parts carbon powder.

[0044] The preparation method of the anti-oxidation and anti-decarburization coating for steel billets in this embodiment includes the following steps:

[0045] Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for 30 seconds to ensure that the solvent and adhesive are fully mixed.

[0046] Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from clumping in the solvent. Stir for 10 minutes after pouring completely.

[0047] Step 3: Pour the additive into the container where the solvent and coating are mixed, and stir continuously and evenly for 10 minutes. After mixing evenly, let it stand for 5 minutes to obtain the anti-oxidation and anti-decarburization coating for steel billets.

[0048] The method of using the anti-oxidation and anti-decarburization coating for steel billets in this embodiment is to quickly load the uniformly stirred and allowed to stand into the spraying machine and spray it onto the surface of 100CrMnSi6-4 bearing steel billets. The temperature of the steel billets during spraying is ≤50℃. One layer is sprayed, and the thickness of the resulting coating is 0.1~0.2mm. After the steel billets are coated, they are directly put into the high-temperature furnace.

[0049] The high-temperature furnace temperature is ≤850℃, the maximum heating temperature is 1180-1270℃, and the total heating time is 450min.

[0050] Example 4

[0051] This embodiment provides a steel billet anti-oxidation and anti-decarburization coating, comprising the following components in parts by weight:

[0052] The high-temperature resistant coating consists of 50 parts kaolin, 20 parts silica sol as a binder, 20 parts ethanol as a solvent, 9 parts anhydrous sodium carbonate, and 1 part carbon powder.

[0053] The preparation method of the anti-oxidation and anti-decarburization coating for steel billets in this embodiment includes the following steps:

[0054] Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for 30 seconds to ensure that the solvent and adhesive are fully mixed.

[0055] Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from clumping in the solvent. Stir for 10 minutes after pouring completely.

[0056] Step 3: Pour the additive into the container where the solvent and coating are mixed, and stir continuously and evenly for 10 minutes. After mixing evenly, let it stand for 5 minutes to obtain the anti-oxidation and anti-decarburization coating for steel billets.

[0057] The method of using the anti-oxidation and anti-decarburization coating for steel billets in this embodiment is to quickly load the uniformly stirred and allowed to stand into the spraying machine and spray it onto the surface of 100CrMnSi6-4 bearing steel billets. The temperature of the steel billets during spraying is ≤50℃. One layer is sprayed, and the thickness of the resulting coating is 0.1~0.2mm. After the steel billets are coated, they are directly put into the high-temperature furnace.

[0058] The high-temperature furnace temperature is ≤850℃, the maximum heating temperature is 1180-1270℃, and the total heating time is 450min.

[0059] Steel billets of 17NiCrMo6-4 carburizing steel, coated with anti-oxidation and anti-decarburization paint and uncoated steel, were subjected to high-temperature furnace heat treatment. The burn loss rate and decarburization depth of the steel billets after heat treatment were tested respectively, and the results are shown in Table 1 and Table 2.

[0060] Table 1

[0061]

[0062] Table 2

[0063]

[0064] As shown in the comparison of the data in Tables 1 and 2, the burn loss rate of steel billets coated with paint is 1.37%, while that of steel billets without paint is 1.87%. The burn loss of steel billets coated with paint is 26.7% lower than that of steel billets without paint.

[0065] After applying the coating, the decarburization layer of the steel tested ranged from 0.02 to 0.1 mm, with an average of 0.06 mm. The minimum decarburization depth was 0 mm in 90% of the tests, and approximately 3% of single-point tests showed a decarburization depth of 0.1 mm, while the rest were 0-0.1 mm, indicating a significant lack of depth. For the steel without the coating, the decarburization layer ranged from 0.06 to 0.18 mm, with an average of 0.13 mm. The maximum depth was 0.18 mm in 40% of the tests, 0.06-0.1 mm in 20% of the tests, and less than 0.06 mm in 40% of the tests. The test results show that the decarburization layer depth of the coated steel was significantly reduced, with an average depth 53.85% lower than that of the uncoated steel.

Claims

1. A coating for preventing oxidation and decarburization of steel billets, characterized in that, It contains the following components in parts by weight: The high-temperature resistant coating comprises 40-50 parts, a binder comprises 10-20 parts, a solvent comprises 20 parts, and an additive comprises 10 parts. The high-temperature resistant coating is kaolin, the binder is silica sol, the solvent is water or ethanol, and the additive is a combination of anhydrous sodium carbonate and carbon powder, or a combination of anhydrous sodium carbonate and graphite powder.

2. The anti-oxidation and anti-decarburization coating for steel billets according to claim 1, characterized in that, The weight ratio of anhydrous sodium carbonate to carbon powder is 1:0.1~10, and the weight ratio of anhydrous sodium carbonate to graphite powder is 1:0.1~10.

3. A method for preparing an anti-oxidation and anti-decarburization coating for steel billets as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Place the solvent in a container according to the weight proportions, and pour the adhesive into the container containing the solvent. Stir for a certain period of time to ensure that the solvent and adhesive are fully mixed. Step 2: Pour the high-temperature resistant coating into the container where the solvent and binder are mixed. During the pouring process, the solvent should be stirred continuously and evenly to prevent the high-temperature resistant coating from forming in the solvent. Stir for a certain period of time after pouring. Step 3: Pour the additive into the container where the stirred solvent and coating are mixed, and stir continuously and evenly. After mixing evenly, let it stand for a certain period of time to obtain the steel billet anti-oxidation and anti-decarburization coating.

4. The method for preparing the anti-oxidation and anti-decarburization coating for steel billets according to claim 3, characterized in that, The stirring time in step one is 30-60 seconds.

5. The method for preparing the anti-oxidation and anti-decarburization coating for steel billets according to claim 4, characterized in that, The stirring time in step two is 10-15 minutes.

6. The method for preparing the anti-oxidation and anti-decarburization coating for steel billets according to claim 4, characterized in that, The stirring time in step three is 10-15 minutes, and the settling time is 5-10 minutes.

7. A method of using the anti-oxidation and anti-decarburization coating for steel billets as described in claim 1 or 2, characterized in that, After being thoroughly mixed and allowed to stand, the anti-oxidation and anti-decarburization coating for the steel billet is loaded into a spraying machine and sprayed onto the surface of the steel billet. After the coating is applied, the steel billet is directly placed into a high-temperature furnace.

8. The method of using the anti-oxidation and anti-decarburization coating for steel billets according to claim 7, characterized in that, If the anti-oxidation and anti-decarburization coating for the steel billet is left to stand for more than 10 minutes before application, it needs to be stirred again before use.

9. The method of using the anti-oxidation and anti-decarburization coating for steel billets according to claim 7 or 8, characterized in that, The billet temperature should be ≤50℃ during spraying.

10. The method of using the anti-oxidation and anti-decarburization coating for steel billets according to claim 7, characterized in that, The thickness of the coating obtained by spraying is 0.1~0.2mm.

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