阅读说明：本技术 一种轴承钢转炉低氧出钢生产方法 (Low-oxygen steel tapping production method for bearing steel converter ) 是由 陈永峰 陶群南 张洪彪 左小坦 陈钰德 赵立 王吾磊 杨伟勇 刘华 黄雁 张亚兵 于 2020-12-18 设计创作，主要内容包括：本发明提供了一种轴承钢转炉低氧出钢生产方法,通过对铁水各化学成分做了要求,便于控制出站的磷含量；进行铁水预脱磷：控制脱磷剂按27-32kg/t量加入；喷粉速度控制42-48kg/min；氧气枪位：1100-1250mm；氧气流量：10-15Nm～3/min。出站时铁水P≤0.015％；转炉冶炼：采用纯脱磷铁水进行顶底复吹冶炼,冶炼中加入石灰、返矿、压球进行造渣,吹炼过程枪位：1600-1800mm；氧气流量：26000-28000Nm～3/h；控制出钢成分：C≥0.15％、P≤0.015％,Ti≤0.0020％,T.O≤20ppm；出钢温度≥1620℃,最终降低钢水中氧的含量,减少大颗粒夹杂物。(The invention provides a low-oxygen steel tapping production method of a bearing steel converter, which is convenient for controlling the phosphorus content of discharged molten iron by making requirements on various chemical components of the molten iron; carrying out molten iron dephosphorization in advance: the dephosphorization agent is added according to the amount of 27-32 kg/t; controlling the powder spraying speed to be 42-48 kg/min; oxygen gun position: 1100-1250 mm; oxygen flow rate: 10-15Nm 3 And/min. When the molten iron is discharged, the molten iron P is less than or equal to 0.015 percent; smelting in a converter: carrying out top-bottom combined blowing smelting by adopting pure dephosphorized molten iron, adding lime, returning ores and pressing balls in the smelting process for slagging, wherein the lance position in the blowing process is as follows: 1600-1800 mm; oxygen flow rate: 26000 and 28000Nm 3 H; controlling tapping components: more than or equal to 0.15 percent of C, less than or equal to 0.015 percent of P, less than or equal to 0.0020 percent of Ti and less than or equal to 20ppm of T.O; the tapping temperature is more than or equal to 1620 ℃, and finally the oxygen content in the molten steel is reduced, and large-particle inclusions are reduced.)

1. A production method of low-oxygen steel tapping of a bearing steel converter is characterized by comprising the following steps:

1) pre-dephosphorizing molten iron: oxygen gun position: 1100-1250 mm; oxygen flow rate: 10-15Nm³/min；

2) Smelting in a converter: smelting by top-bottom combined blowing, and controlling tapping components: more than or equal to 0.15 percent of C, less than or equal to 0.015 percent of P, less than or equal to 0.0020 percent of Ti, and less than or equal to 20ppm of T.O.

2. The production method according to claim 1, wherein in the step 1), the requirements on the composition and temperature of the molten iron are as follows: less than or equal to 0.25 percent of Si, less than or equal to 0.070 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.035 percent of Ti, less than or equal to 0.030 percent of As, less than or equal to 0.001 percent of Pb, less than or equal to 0.030 percent of Sn, less than or equal to 0.004 percent of Sb, and less than or equal to 0.070 percent of As +; the temperature is more than or equal to 1250 ℃.

3. The production method according to claim 1 or 2, wherein in the step 1), the molten iron is subjected to slagging-off treatment in an on-site manner, and then the dephosphorization agent is added in an amount of 27-32 kg/t; controlling the powder spraying speed to be 42-48 kg/min.

4. The production method according to claim 1 or 2, wherein in step 1), the molten iron P is less than or equal to 0.015% at the time of the tapping.

5. The production method according to claim 1, wherein lime, return ores and slag balls are added for slagging in the smelting in the step 2), the adding amount of the lime is 19-23kg/t steel, the adding amount of the return ores is 17-19kg/t steel, and the adding amount of the slag balls is 23-26kg/t steel.

6. According to claim 1The production method is characterized in that in the step 2), the lance position in the converting process is as follows: 1600-1800 mm; oxygen flow rate: 26000 and 28000Nm³/h。

7. The production method according to claim 1, wherein in step 2), the tapping temperature is not less than 1620 ℃.

Technical Field

The invention belongs to the field of alloy smelting, and particularly relates to a low-oxygen steel tapping production method of a bearing steel converter.

Background

With the coming of the national fourteen-five planning, the material transformation will develop towards the high-precision special direction, and the requirement on the purity of molten steel is higher and higher. The demand for bearing steel will further expand, and the quality grade of bearing steel will be more and more demanding. Although steel mills for producing bearing steel in China have been developed at the initial scale at present, such as Xingcheng, Bao steel and the like, the annual output reaches millions of tons. However, compared with foreign steel mills, there is a gap in the quality grade of the product, mainly in the aspect of the inclusion control level, and the content of the inclusions is directly related to the oxygen potential in the molten steel. At present, a double-slag or multi-slag smelting method is generally adopted for producing bearing steel, although the method is favorable for dephosphorization and titanium removal, the operation is unstable depending on post working experience, if the phosphorus content is high, low-gun blowing is adopted, so that the end point carbon content is low, the steel tapping temperature is high, the steel tapping oxygen potential is increased, and the subsequent refining treatment and the finished product oxygen content are adversely affected. Therefore, if the low-oxygen steel tapping of the bearing steel converter is stably controlled, the method has great significance for controlling the inclusion of the bearing steel and improving the quality grade of the bearing steel product.

Disclosure of Invention

The invention aims to provide a low-oxygen steel tapping production method of a bearing steel converter, which is convenient for controlling the phosphorus content of discharged steel by making requirements on various chemical components of molten iron; in addition, the designed molten iron pre-dephosphorization technology is beneficial to the follow-up carbon-retaining and steel-tapping of the converter, and the oxygen content in the molten steel is reduced. The low-oxygen tapping production method of the bearing steel converter provided by the invention can maintain the tapping oxygen content of the bearing steel converter at a lower level.

The specific technical scheme of the invention is as follows:

a production method of low-oxygen steel tapping of a bearing steel converter comprises the following steps:

1) pre-dephosphorizing molten iron: oxygen gun position: 1100-1250 mm; oxygen flow rate: 10-15Nm³/min；

2) Smelting in a converter: smelting by top-bottom combined blowing, and controlling tapping components: more than or equal to 0.15 percent of C, less than or equal to 0.015 percent of P, less than or equal to 0.0020 percent of Ti, and less than or equal to 20ppm of T.O.

Further, in the step 1), the requirements on the components and the temperature of the molten iron are as follows: less than or equal to 0.25 percent of Si, less than or equal to 0.070 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.035 percent of Ti, less than or equal to 0.030 percent of As, less than or equal to 0.001 percent of Pb, less than or equal to 0.030 percent of Sn, less than or equal to 0.004 percent of Sb, and less than or equal to 0.070 percent of As +; the temperature is more than or equal to 1250 ℃.

Further, in the step 1), slagging off is carried out on molten iron in a station, and then a dephosphorizing agent is added according to the amount of 27-32 kg/t; controlling the powder spraying speed to be 42-48 kg/min;

further, in the step 1), the molten iron P is less than or equal to 0.015 percent when the molten iron is discharged.

Further, lime, return ores and slag pressing balls are added in the smelting in the step 2) for slagging, wherein the addition amount of the lime is 19-23kg/t of steel, the addition amount of the return ores is 17-19kg/t of steel, and the addition amount of the slag pressing balls is 23-26kg/t of steel;

further, in the step 2), the lance position in the blowing process: 1600-1800 mm; oxygen flow rate: 26000 and 28000Nm³/h。

In the step 2), the tapping temperature is more than or equal to 1620 ℃.

According to the invention, by the designed molten iron pre-dephosphorization process, phosphorus and titanium in the molten iron are reduced, and the carbon content of converter tapping is increased, so that the oxygen content in the tapping process is reduced, the purity of the molten steel is improved, and large-particle inclusions are reduced; thereby improving the brand benefits of enterprises.

The invention provides a production method of low-oxygen steel tapping of a bearing steel converter, which adopts the high-efficiency, low-cost and energy-saving process route production of molten iron pre-dephosphorization and pure molten iron converter blowing, reduces the oxygen content of the converter steel tapping and improves the quality of the bearing steel product by perfecting the production flow and carrying out optimized research and control on key working procedures. The total oxygen content T.O of the molten steel tapped from the converter produced by the production method is less than or equal to 20 ppm.

Drawings

FIG. 1 shows the structure of the GCr15 bearing steel rolled material prepared by the method of the invention;

FIG. 2 shows the structure of the GCr15 steel rolling material prepared by the comparative example.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.

The present invention will be further described with reference to the following examples.

Example 1 to example 3

A production method of low-oxygen steel tapping of a bearing steel converter comprises the following steps:

1) pre-dephosphorizing molten iron: the molten iron has the following components and temperature requirements: less than or equal to 0.25 percent of Si, less than or equal to 0.070 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.035 percent of Ti, less than or equal to 0.030 percent of As, less than or equal to 0.001 percent of Pb, less than or equal to 0.030 percent of Sn, less than or equal to 0.004 percent of Sb, less than or equal to 0.070 percent of As + Sn + Sb, and; the molten iron pre-dephosphorization comprises the following steps: carrying out slagging-off treatment on molten iron in a station, and then adding a dephosphorizing agent according to the amount of 27-32 kg/t; controlling the powder spraying speed to be 42-48 kg/min; oxygen gun position: 1100-1250 mm; oxygen flow rate: 10-15Nm³Min; go out of stationThe molten iron P is less than or equal to 0.015 percent, and the specific process parameter control is shown in tables 1-3.

2) Smelting in a converter: adopting 130 tons of pure dephosphorized molten iron to carry out top-bottom combined blowing smelting, adding lime, return ores and slag pressing balls to carry out slagging in the smelting process, wherein the adding amount of the lime is 19-23kg/t steel, the adding amount of the return ores is 17-19kg/t steel, the adding amount of the slag pressing balls is 23-26kg/t steel, and the lance position in the blowing process: 1600-1800 mm; oxygen flow rate: 26000 and 28000Nm³H; controlling tapping components: more than or equal to 0.15 percent of C, less than or equal to 0.015 percent of P, less than or equal to 0.0020 percent of Ti and less than or equal to 20ppm of T.O; the tapping temperature is more than or equal to 1620 ℃, and the specific process parameter control is shown in Table 4.

Examples 1-3 before preliminary dephosphorization of molten iron the chemical composition and temperature data of molten iron in each example are shown in table 1, and the remaining components were controlled according to the prior art.

TABLE 1 chemical composition (wt%) and temperature data of molten iron in each example and comparative example before preliminary dephosphorization of molten iron

The technological parameters of the embodiments of the pre-dephosphorization of molten iron of the invention are shown in Table 2.

TABLE 2 Process parameters of examples of preliminary dephosphorization of molten iron

The chemical components and temperature data of the molten iron in the embodiments after the molten iron is dephosphorized in advance are shown in the table 3, and the other components are controlled according to the prior art.

TABLE 3 chemical composition (wt%) and temperature data of molten iron in each example after preliminary dephosphorization of molten iron

TABLE 4 Process parameters of the converter smelting in each example and comparative example

TABLE 5 Main chemical composition (wt%) and temperature data of molten steel in each example and comparative example after completion of converter smelting

The balance not shown in table 5 is Fe and unforeseeable impurities.

Comparative examples 1 to 3

A production method of low-oxygen steel tapping of a bearing steel converter comprises the following steps:

1) the pre-desulfurization treatment of the molten iron is not carried out, the components and the temperature requirements of the molten iron are shown in the table 1, and the other components are controlled according to the prior art.

2) Directly carrying out converter smelting: the specific process parameters are shown in Table 4, and the main chemical components (wt%) and temperature data of the molten steel in each example and comparative example after the converter smelting are shown in Table 5.

After converter smelting according to the methods described in examples 1-3 and comparative examples 1-3, LF ladle refining, RH vacuum degassing, continuous casting, heating, high pressure water descaling, rolling, cooling, trimming, inspecting, and packaging were performed according to the same prior art. The inclusions and texture of the obtained product are shown in Table 6.

TABLE 6 inclusions and texture of rolled stock

The invention reduces phosphorus and titanium in the molten iron and improves the carbon content of the converter during tapping by dephosphorizing the molten iron in advance, thereby reducing the oxygen content in the tapping process, improving the purity of the molten steel and reducing large-particle inclusions.

The invention has been described in detail with respect to the general description and the specific examples, but it will be apparent to those skilled in the art that modifications or improvements may be made based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.