阅读说明：本技术 一种表层高碳含量铸坯的制造方法 (Manufacturing method of casting blank with high carbon content on surface layer ) 是由 黄玉平 赵成林 李冰 李德军 廖相巍 康伟 尚德礼 张晓光 赵亮 许孟春 于 2019-09-30 设计创作，主要内容包括：本发明涉及一种表层高碳含量铸坯的制造方法,钢坯的连铸过程中,在结晶器内靠近结晶器壁0～100mm范围内的保护渣表面上加入自发热增碳剂,自发热增碳剂放出大量的热熔化保护渣,并与其混合形成碳含量很高的增碳保护渣流入器坯缝隙,增碳保护渣接触弯月面处的钢液及高温的初生坯壳,碳元素扩散进入。随着坯壳厚度增加及温度下降,碳元素向铸坯内扩散速度急剧下降,甚至停止扩散。于是获得表层相对高碳含量,内部低碳含量的表层高碳连铸坯。本发明在连铸过程中实现铸坯表层增碳,无需附加的增碳处理工序；渗碳层厚度大；成本低；效率高。(The invention relates to a method for manufacturing a casting blank with a high carbon content on the surface layer, which is characterized in that during the continuous casting of a steel billet, a self-heating recarburizing agent is added on the surface of protective slag in a crystallizer, which is close to the wall of the crystallizer within the range of 0-100 mm, a large amount of hot melting protective slag is discharged by the self-heating recarburizing agent and is mixed with the protective slag to form a recarburizing protective slag flowing device blank gap with high carbon content, the recarburizing protective slag contacts with molten steel at the meniscus and a high-temperature primary blank shell, and carbon elements are diffused. Along with the increase of the thickness of the shell and the reduction of the temperature, the diffusion speed of the carbon element into the casting blank is sharply reduced, and even the diffusion is stopped. Thus, the surface high-carbon continuous casting billet with relatively high carbon content on the surface and low carbon content inside is obtained. According to the invention, the surface layer of the casting blank is carburized in the continuous casting process, and an additional carburization treatment process is not required; the carburized layer is thick; the cost is low; the efficiency is high.)

1. The manufacturing method of the casting blank with the high carbon content on the surface layer is characterized by comprising the following specific steps:

1) after the continuous casting is started, a self-heating recarburizing agent distributor is used for distributing and scattering a self-heating recarburizing agent above the covering slag within a range of 0-100 mm away from the inner wall of the crystallizer, the self-heating recarburizing agent is kept to cover the liquid level of the steel all the time, and the thickness of the self-heating recarburizing agent is within a range of 0.1-10 mm;

2) the self-heating recarburizer is heated by the covering slag, the self-heating recarburizer and the surface layer solid covering slag are melted and mixed with the molten covering slag to form recarburizer covering slag, and the recarburizer covering slag flows into a gap between the crystallizer and the casting blank;

3) the recarburization covering slag is contacted with the meniscus molten steel, carbon elements in the self-heating recarburization agent are diffused to the molten steel near the meniscus, and the recarburized molten steel is solidified to form a primary high-temperature blank shell;

4) and the recarburizing covering slag flows into a gap between the crystallizer and the primary high-temperature blank shell and is always contacted with the molten steel and the solidified blank shell, and in the process, the carbon element in the self-heating recarburizing agent is continuously diffused to the surface layer of the casting blank to obtain a surface layer high-carbon continuous casting blank with relatively high carbon content on the surface layer and low carbon content inside the casting blank.

2. The method for manufacturing the casting blank with the high carbon content on the surface layer according to claim 1, wherein the self-heating carburant comprises the following components in percentage by weight: al: 5% -30%, C: 20 to 65% of SiO₂：5％～30％，Na₂O：0.1％～20％，K₂O：0.1％～20％，CaO：0.1％～20％。

3. The method for manufacturing the surface-layer high-carbon-content casting blank according to claim 1, wherein the surface-layer high-carbon casting blank has a recarburization layer thickness of 0.1-12 mm, the mass percentage of carbon in the outermost surface layer is 0.05-3.5%, and the carbon content gradually decreases towards the inside of the casting blank until the carbon content is the same as that of the matrix.

Technical Field

The invention relates to the field of ferrous metallurgy, in particular to a method for manufacturing a casting blank with a high carbon content on the surface layer.

Background

The steel with high carbon content on the surface layer is composite performance steel with toughness of base steel and different performances of high hardness and high strength of the surface layer steel, can greatly improve the comprehensive performance and the service life of the steel in the use process, and is a development direction for steel application. However, few methods are available for carburizing the surface layer of steel, and the cost is high, for example, carburization and the like, the thickness of the carbon-added layer on the surface layer is small, so that it is difficult to completely meet the performance requirements, and the cost of treatment is high, which results in high price. At present, continuous casting is the main production method of steel, so that a method for producing a steel casting blank at a lower cost and with higher efficiency while realizing surface layer carburization is urgently needed.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for manufacturing a casting blank with a high carbon content on the surface layer, so that the surface layer of the casting blank is carburized in the continuous casting process, and an additional carburization treatment process is not needed.

In order to achieve the purpose, the invention adopts the following technical scheme:

a manufacturing method of a casting blank with a high carbon content on the surface layer specifically comprises the following steps:

1) after the continuous casting is started, a self-heating recarburizing agent distributor is used for distributing and scattering a self-heating recarburizing agent above the covering slag within a range of 0-100 mm away from the inner wall of the crystallizer, the self-heating recarburizing agent is kept to cover the liquid level of the steel all the time, and the thickness of the self-heating recarburizing agent is within a range of 0.1-10 mm;

2) the self-heating recarburizer is heated by the covering slag, the self-heating recarburizer and the surface layer solid covering slag are melted and mixed with the molten covering slag to form recarburizer covering slag, and the recarburizer covering slag flows into a gap between the crystallizer and the casting blank;

3) the recarburization covering slag is contacted with the meniscus molten steel, carbon elements in the self-heating recarburization agent are diffused to the molten steel near the meniscus, and the recarburized molten steel is solidified to form a primary high-temperature blank shell;

4) and the recarburizing covering slag flows into a gap between the crystallizer and the primary high-temperature blank shell and is always contacted with the molten steel and the solidified blank shell, and in the process, the carbon element in the self-heating recarburizing agent is continuously diffused to the surface layer of the casting blank to obtain a surface layer high-carbon continuous casting blank with relatively high carbon content on the surface layer and low carbon content inside the casting blank.

The self-heating carburant comprises the following components in percentage by weight: al: 5% -30%, C: 20 to 65% of SiO₂：5％～30％，Na₂O：0.1％～20％，K₂O：0.1％～20％，CaO：0.1％～20％。

The surface layer high-carbon casting blank is 0.1-12 mm thick in recarburization layer, the mass percentage content of carbon on the outermost surface layer is 0.05-3.5%, and the carbon content gradually decreases towards the interior of the casting blank until the carbon content is the same as that of the matrix.

Compared with the prior art, the invention has the beneficial effects that:

1) the surface layer of the casting blank is carburized in the continuous casting process, and an additional carburization treatment process is not needed.

2) The carburized layer is thick.

3) The cost is low.

4) The efficiency is high.

Drawings

FIG. 1 is a schematic diagram of the recarburization treatment of the surface layer of a casting blank in the continuous casting process.

In the figure: the device comprises a carburant distributor 1, a self-heating carburant 2, a crystallizer 3, molten covering slag 4, solid covering slag 5, molten steel 6, a slag ring 7, a solidified blank shell 8, solidified covering slag 9 and carburant covering slag 10.

Detailed Description

The following further describes embodiments of the present invention with reference to the accompanying drawings:

a manufacturing method of a casting blank with a high carbon content on the surface layer comprises the following specific steps:

1. preparing a self-heating carburant, wherein the self-heating carburant comprises the following components in percentage by weight: al: 5% -30%, C: 20 to 65% of SiO₂：5％～30％，Na₂O：0.1％～20％，K₂O：0.1％～20％，CaO：0.1％～20％。

2. Placing a self-heating recarburizer into a recarburizer distributor additionally arranged above the crystallizer;

3. after the continuous casting starts, the carburant distributor vibrates along with the crystallizer;

4. as shown in figure 1, the self-heating recarburizer flows out by vibration and falls into the crystallizer on the casting powder within 0-100 mm from the wall of the crystallizer. Keeping the self-heating recarburizer to cover the steel liquid level all the time, wherein the thickness of the self-heating recarburizer is within the range of 2-10 mm; the self-heating recarburizer falls into the crystallizer, the self-heating recarburizer is heated by the covering slag, the aluminum powder reacts with oxygen in the air, the self-heating recarburizer and the surface layer solid covering slag are melted by heating, and the self-heating recarburizer and the surface layer solid covering slag are mixed together to form recarburizer covering slag and flow into a gap between the crystallizer and a casting blank;

5. the recarburization covering slag is contacted with the meniscus molten steel, carbon elements in the self-heating recarburization agent are diffused to the molten steel near the meniscus, and the recarburized molten steel is solidified to form a primary high-temperature blank shell;

6. then the recarburization covering slag flows into a gap between the crystallizer and the primary high-temperature casting blank shell and is always contacted with the molten steel and the solidified blank shell, and in the process, the carbon element in the self-heating recarburization agent continuously diffuses towards the surface layer of the casting blank. Along with the increase of the thickness of the shell and the reduction of the temperature, the diffusion speed of the carbon element into the casting blank is sharply reduced, and even the diffusion is stopped. Thus, a surface-layer high-carbon cast slab was obtained.