阅读说明：本技术 一种高碳钢线材中CaO类夹杂物的控制方法 (Control method of CaO inclusion in high-carbon steel wire ) 是由 周彦召 马建超 赵家七 蔡小锋 于 2020-12-21 设计创作，主要内容包括：本申请公开了高碳钢线材中CaO类夹杂物的控制方法,工艺流程为转炉冶炼-LF精炼-连续浇注,(1)、转炉冶炼：终点碳含量为0.03％-0.05％,终点钢液温度≥1660℃；(2)LF精炼：根据LF到站钢液的化学成分,喂入碳粉包芯线调节钢液的碳含量至目标成分,同时开启钢包底吹,底吹强度为4-6L/(min·t)；钢液化学成分达到目标成分后,关闭钢包底吹,加入8-12kg/t的合成渣。采用本发明的控制方法夹杂物中的CaO组分的比例从25％以上降低到10％以下。(The application discloses a control method of CaO inclusion in high-carbon steel wire, which comprises the following process flows of converter smelting, LF refining and continuous casting, (1) converter smelting: the end point carbon content is 0.03-0.05%, and the end point molten steel temperature is more than or equal to 1660 ℃; (2) LF refining: feeding a carbon powder cored wire to adjust the carbon content of the molten steel to a target component according to the chemical components of the LF arrival station molten steel, and simultaneously starting steel ladle bottom blowing, wherein the bottom blowing strength is 4-6L/(min.t); and (3) after the chemical components of the molten steel reach the target components, closing the bottom blowing of the steel ladle, and adding 8-12kg/t of synthetic slag. The proportion of CaO component in the inclusions is reduced from more than 25% to less than 10% by the control method of the invention.)

1. A control method of CaO inclusion in high-carbon steel wire rods comprises the following process flows of converter smelting, LF refining and continuous casting, and is characterized in that: (1) and smelting in a converter: the end point carbon content is 0.03-0.05%, and the end point molten steel temperature is more than or equal to 1660 ℃; (2) LF refining: feeding a carbon powder cored wire to adjust the carbon content of the molten steel to a target component according to the chemical components of the LF arrival station molten steel, and simultaneously starting steel ladle bottom blowing, wherein the bottom blowing strength is 4-6L/(min.t); after the chemical components of the molten steel reach the target components, the bottom blowing of the steel ladle is closed, and 8-12kg/t of high-carbon steel synthetic slag is added.

2. The method for controlling CaO-based inclusions in a high-carbon steel wire rod according to claim 1, wherein: in the LF refining process, the wire feeding speed of the carbon powder core-spun wire is 2-6 m/s.

3. The method for controlling CaO-based inclusions in a high-carbon steel wire rod according to claim 1, wherein: the type of the inclusion in the iron sheet of the carbon powder cored wire is SiO₂MnO system, the particle size of the carbon powder is 1-5 mm.

4. The method for controlling CaO-based inclusions in a high-carbon steel wire rod according to claim 1, wherein: in the LF refining process, after high-carbon steel synthetic slag is added, a heat insulation structure of a melting layer, a solid-liquid layer and a solid-phase layer is formed on the surface of the molten steel.

5. The method for controlling CaO-based inclusions in a high-carbon steel wire rod according to claim 1, wherein: in the converter process, 2-5t of steel is left in the converter after the steel discharge of the converter is finished.

Technical Field

The invention belongs to the field of ferrous metallurgy, and particularly relates to a control method of CaO inclusions in high-carbon steel wires.

Background

Inclusions in the high-carbon steel wire mainly comprise two types of MnO-SiO2-Al2O3, CaO-SiO2-Al2O3-MgO and the like. Related researches show that MnO-SiO2-Al2O3 type inclusions are deoxidation products and belong to internal inclusions, and CaO-SiO2-Al2O3-MgO is external inclusions caused by entrainment of refining slag into molten steel for emulsification. High SiO2 inclusions such as MnO-SiO2-Al2O3 and the like are broken during drawing and become discontinuous and fine point-shaped inclusions along the rolling direction, so that the problems of wire breakage and the like are not easily caused. Therefore, the reduction of the amount of CaO-SiO2-Al2O 3-MgO-based inclusions is a key technology for the control of high-carbon steel wire rods.

Patent 201811271908.0 discloses a method for controlling inclusions in high carbon steel, which significantly refines the size of inclusions by magnesium treatment, widens the control range of inclusions in alumina in high carbon steel, and suppresses the precipitation of network carbides in high carbon steel.

Patent 201510975576.4 discloses a method for controlling non-metallic inclusions in cord steel LX72A, which reduces the total amount of inclusions and avoids large-particle brittleness and invariable inclusions by measures such as high-carbon steel tapping of a converter, high alkalinity of LF refining, soft stirring and the like. Although a series of patents address the problem of partial inclusions in high carbon steel wire, the control of high CaO inclusions in high carbon steel wire is still a problem to be solved.

Disclosure of Invention

The invention aims to provide a method for controlling CaO inclusions in high-carbon steel wires, which overcomes the defects in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: a control method of CaO inclusion in high-carbon steel wire comprises the following process flows of converter smelting, LF refining and continuous casting, (1) converter smelting: the end point carbon content is 0.03-0.05%, and the end point molten steel temperature is more than or equal to 1660 ℃; (2) LF refining: feeding a carbon powder cored wire to adjust the carbon content of the molten steel to a target component according to the chemical components of the LF arrival station molten steel, and simultaneously starting steel ladle bottom blowing, wherein the bottom blowing strength is 4-6L/(min.t); after the chemical components of the molten steel reach the target components, the bottom blowing of the steel ladle is closed, and 8-12kg/t of high-carbon steel synthetic slag is added. The chemical components of the high-carbon steel synthetic slag are CaO 40-45% and SiO₂50% -55%, and the others are impurities.

In the technical scheme, the refining adopts carbon wire for recarburization, so that the phenomenon that the slag is seriously rolled and the content of CaO component in the inclusion is increased in the traditional mode of directly adding a recarburizing agent from the slag surface can be avoided.

As a preferred embodiment of the invention, in the LF refining process, the wire feeding speed of the carbon powder cored wire is 2-6 m/s.

As a preferred embodiment of the invention, the type of the inclusion in the iron sheet of the carbon powder cored wire is SiO₂MnO system, the particle size of the carbon powder is 1-5 mm.

In a preferred embodiment of the present invention, in the LF refining process, after the high-carbon steel synthetic slag is added, a heat insulation structure having a melting layer, a solid-liquid layer, and a solid-phase layer is formed on the surface of the molten steel.

In the technical scheme, after the synthetic slag is added, a unique slag-absorbing heat-preserving structure of a melting layer, a solid-liquid layer and a solid-phase layer is formed on the surface of the molten steel by means of heat conduction of the molten steel, and CaO-type inclusions in the molten steel are further removed.

As a preferred embodiment of the invention, in the converter process, 2-5t of steel is left in the converter after the tapping of the converter is finished.

In the technical scheme, steel retaining operation is carried out in the converter process, slag discharging is avoided, and CaO inclusion caused by converter slag discharging involved in molten steel is reduced.

Compared with the prior art, the invention has at least the following beneficial effects:

1) through the cooperative control of converter blowing and LF refining, the appearance of high-CaO inclusions is stopped from the source, the controllability of the high-CaO inclusions is realized, and the proportion of CaO components of the inclusions in the wire rod is reduced from more than 25 percent to less than 10 percent.

2) The carbon yield is improved by the form of carbon powder cored wire, and is improved by more than 99 percent from 90 percent;

3) according to the GB \ T10561 rating standard, the rating of the inclusions of the wire rod is reduced from more than 2.0 grade to 0.5 grade and below;

drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a diagram showing typical CaO inclusions after the practice of the present invention.

FIG. 2 is a diagram showing typical CaO-based inclusions in comparative examples of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

The proportion of the CaO component in the high-CaO inclusions in the high-carbon steel wire rod is shown in Table 1 by carrying out a method for controlling the high-CaO inclusions. The specific implementation scheme is as follows:

1) smelting in a converter: the final carbon content of the converter is 0.045%, the final temperature is 1666 ℃, no carburant is added in the converter tapping, and 2.5t of steel is left in the converter after the tapping is finished.

2) LF refining: according to the chemical components of the LF arrival station molten steel, carbon content is adjusted to target components by feeding carbon powder cored wires, the wire feeding speed of the carbon powder cored wires is 4m/s, the type of inclusions in iron sheets of the cored wires is SiO2-MnO system, and the particle size of the carbon powder is 1-5 mm. And adding other alloy elements of corresponding steel grades, and starting ladle bottom blowing, wherein the bottom blowing strength is 4.5L/(min. t). And after the chemical components of the molten steel meet the target requirements, closing bottom blowing, and adding 9kg/t of high-carbon steel synthetic slag. The chemical components of the high-carbon steel synthetic slag are CaO 40-45% and SiO₂50% -55%, and the others are impurities.

3) And (4) continuously casting.

According to the wire rod produced by the embodiment, the grade of the inclusions in the wire rod is 0.5 according to the national standard GT \ B10561, the proportion of CaO components in CaO-containing inclusions is shown in Table 1, and the yield of carbon powder of the carbon powder cored wire reaches 99.2%.

Table 1 composition of inclusions in example 1

Example 2

The ratio of the CaO component in the high-CaO inclusions in the high-carbon steel wire rods is shown in Table 2 by carrying out a method for controlling the high-CaO inclusions. The specific implementation scheme is as follows:

1) smelting in a converter: the carbon content at the end point of the converter is 0.033 percent, the end point temperature is 1680 ℃, no carburant is added in the converter tapping, and 4.5t of steel is left in the converter after the tapping is finished.

2) LF refining: according to the chemical composition of LF arrival molten steel, by feeding carbon powder bagsThe core wire adjusts the carbon content to the target composition, the wire feeding speed of the carbon powder core-spun wire is 6m/s, the type of inclusions in the iron sheet of the core-spun wire is SiO2-MnO system, and the particle size of the carbon powder is 1-5 mm. And adding other alloy elements of corresponding steel grades, and starting ladle bottom blowing, wherein the bottom blowing strength is 5.7L/(min. t). And after the chemical components of the molten steel meet the target requirements, closing bottom blowing, and adding 11kg/t of high-carbon steel synthetic slag. The chemical components of the high-carbon steel synthetic slag are CaO 40-45% and SiO₂50% -55%, and the others are impurities.

3) And (4) continuously casting.

According to the wire rod produced by the embodiment, the grade of the inclusions in the wire rod is 0 according to the national standard GT \ B10561, the CaO content in the CaO-containing inclusions is shown in Table 2, and the yield of the carbon powder cored wire reaches 99.7%.

Table 2 composition of inclusions in example 2

Comparative example 1

The comparative example adopts the following control method to control the high CaO type inclusions in the high carbon steel cord steel wire rod, and the specific implementation scheme is as follows:

1) smelting in a converter: the carbon content at the end point of the converter is 0.07 percent, the end point temperature is 1645 ℃, carbon powder and alloy elements are added in the tapping process of the converter, 1kg/t of lime is added, and a slag blocking plug is adopted to block slag in the tapping process.

2) LF refining: after the steel ladle arrives at the station, 10kg/t of high-carbon steel slag is added, the bottom blowing of the steel ladle is started in the whole process, the bottom blowing strength is 1-6L/(min.t), and temperature measurement sampling is carried out. According to the chemical components of the LF arrival station molten steel, carbon powder is added for recarburization, and other corresponding alloy elements are added. And electrifying to raise the temperature according to the arrival temperature. And after the molten steel reaches the target components and temperature, starting to stir for 25 min.

3) And (4) continuously casting.

In the comparative example, according to the national standard GT \ B10561, the grade of the inclusion in the wire rod is 2.5, and the CaO content in the inclusion containing CaO is as high as 30-40%, as shown in Table 3, the inclusion seriously affects the service performance of the wire rod.

TABLE 3 composition of inclusions in comparative example 1

In conclusion, comparing fig. 1 and 2, the content of CaO in the high carbon steel wire rod according to the method for controlling CaO-based inclusions in the present invention was decreased from 36.5% to 1.6%.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, the use of the phrase "comprising a. -. states" to define an element does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The foregoing is merely a detailed description of the present application, and it should be noted that modifications and embellishments could be made by those skilled in the art without departing from the principle of the present application, and these should also be considered as the protection scope of the present application.