阅读说明：本技术 一种有效控制重轨钢夹杂物组分的控制方法 (Control method for effectively controlling inclusion components of heavy rail steel ) 是由 谌智勇 宋海 辛广胜 刘南 翁举 王文义 高博 杨乐 于 2020-06-29 设计创作，主要内容包括：本发明公开了一种有效控制重轨钢夹杂物组分的控制方法,通过创新性的夹杂物控制理论研究,优化提升钢坯制造冶炼工艺控制,通过精确控制钢轨钢夹杂物的组分,提高夹杂物熔点,来提升夹杂物的去除能力,提升钢轨钢的洁净度控制水平。(The invention discloses a control method for effectively controlling inclusion components of heavy rail steel, which optimizes and improves the control of a billet manufacturing and smelting process through innovative inclusion control theory research, improves the inclusion melting point through accurately controlling the components of the inclusions of the rail steel, improves the removal capability of the inclusions, and improves the cleanliness control level of the rail steel.)

1. A control method for effectively controlling inclusion components of heavy rail steel is characterized by comprising the following steps: the method comprises the following steps:

1) the deoxidizer is silicon-calcium-barium, and comprises the following components in percentage by mass: si is more than or equal to 50 percent, Ca is more than or equal to 13 percent, Ba is more than or equal to 14 percent, Ca + Ba is more than or equal to 28 percent, P is less than or equal to 0.05 percent, and S is less than or equal to 0.10 percent; the alloy uses low-aluminum silicon iron and silicon manganese; at the same time, the content of residual aluminum and calcium in the alloy and the deoxidizer is strictly limited, the residual Al is required to be less than or equal to 1 percent, and the residual Ca is required to be less than 0.5 percent, wherein the content of calcium in silicon, calcium and barium is not limited by the specification;

2) strictly controlling the total amount of residual aluminum and residual calcium brought by the alloy or the deoxidizer according to the oxygen content in the primary steel; the addition of Si, Ca and Ba according to 1) is determined according to the following table:

tapping carbon C](％) Silicon calcium barium addition (kg/t) 0.03 3.5 0.04 2.5 0.05 2.5 0.06 1.5 0.07 1-1.5 0.08 1-1.5 0.09 1 0.10 1 >0.10 1

3) Controlling key indexes of refining slag, wherein the viscosity R is required to be between 1.8 and 2.1, and Al in the slag₂O₃＜5％,MgO＜8％；

4) Selecting an argon blowing control model of the VD soft blowing process, adopting a control model with strength being first strong and then weak, adopting larger air supply strength of 150-200NL/min in the early stage of soft blowing, blowing larger slag hole on the surface of the slag, and then keeping the argon blowing strength at 50-100NL/min in the second stage to ensure that the surface of the slag layer slightly creeps.

2. The method for effectively controlling the inclusion composition of heavy rail steel according to claim 1, wherein the method comprises the following steps: the refining slag control process comprises the following steps: the refining furnace slag-making agent is lime and fluorite, the addition amount of the lime is 5-6 kg/ton steel, the addition amount of the fluorite is 1-2 kg/ton steel, oxygen in silicon carbide slag removal is adopted, the addition amount is 1.5 kg/ton steel, the condition of slag is observed through dipping a slag sample at any time in the smelting process, and the white slag time is kept to be more than or equal to 8min before the refining furnace is out of position.

3. The method for effectively controlling the inclusion composition of heavy rail steel according to claim 1, wherein the method comprises the following steps: the VD soft blowing process control specifically comprises the following steps:

keeping the deep vacuum degree below 30Pa, and keeping the deep vacuum time for 15 min; soft blowing is kept for 15min after deep vacuum breaking, and the two stages are divided, wherein the argon blowing strength is 150-200NL/min in 10min in the first stage, so that a large slag hole is formed on the slag surface; the second stage is performed at 5min argon blowing intensity of 50-100 NL/min.

Technical Field

The invention relates to the technical field of steelmaking and smelting processes, in particular to a control method for effectively controlling inclusion components of heavy rail steel.

Background

The rail is used as the main bearing component of the railway, and in order to adapt to the development requirements of the railway, each steel rail production plant continuously carries out process improvement to improve the cleanliness of steel so as to improve the service performance of the steel rail. In the aspect of the overall technical route for realizing cleanliness control, the steel rail production plants reduce the generation of inclusions and improve the inclusion removal conditions. However, due to the diversity and complexity of inclusions, each rail production plant develops an appropriate technical route according to the characteristics of the respective production control, and the technical details thereof vary greatly. The VD is used as a technical scheme of a degassing process, and due to the fact that steel slag is mixed and stirred for a long time in the VD process, inclusions in molten steel are denatured and generally converted into low-melting-point composite inclusions with multiple components, the inclusions are generally liquid inclusions at the control temperature in the production process, particles are large and are not easy to remove, the inclusions deform into large-size cluster-shaped or point chain-shaped inclusions in the rolling process, the service performance of a steel rail is greatly influenced, and the problems of rail core damage, fracture and the like are caused.

Disclosure of Invention

The invention aims to provide a control method for effectively controlling inclusion components of heavy rail steel, which optimizes and improves the control of a billet manufacturing and smelting process through innovative inclusion control theory research, improves the melting point of inclusions through accurately controlling the components of the inclusions of the rail steel, improves the removal capacity of the inclusions, and improves the cleanliness control level of the rail steel.

In order to solve the technical problems, the invention adopts the following technical scheme:

a control method for effectively controlling inclusion components of heavy rail steel comprises the following steps:

1) the deoxidizer is silicon-calcium-barium, and comprises the following components in percentage by mass: si is more than or equal to 50 percent, Ca is more than or equal to 13 percent, Ba is more than or equal to 14 percent, Ca + Ba is more than or equal to 28 percent, P is less than or equal to 0.05 percent, and S is less than or equal to 0.10 percent; the alloy uses low-aluminum silicon iron and silicon manganese; at the same time, the content of residual aluminum and calcium in the alloy and the deoxidizer is strictly limited, the residual Al is required to be less than or equal to 1 percent, and the residual Ca is required to be less than 0.5 percent, wherein the content of calcium in silicon, calcium and barium is not limited by the specification;

2) strictly controlling the total amount of residual aluminum and residual calcium brought by the alloy or the deoxidizer according to the oxygen content in the primary steel; the addition of Si, Ca and Ba according to 1) is determined according to the following table:

tapping carbon C](％)	Silicon calcium barium addition (kg/t)
		0.03	3.5
0.04	2.5
		0.05	2.5
0.06	1.5
		0.07	1-1.5
0.08	1-1.5
		0.09	1
0.10	1
		>0.10	1

3) Controlling key indexes of refining slag, wherein the viscosity R is required to be between 1.8 and 2.1, and Al in the slag₂O₃＜5％,MgO＜8％；

4) Selecting an argon blowing control model of the VD soft blowing process, adopting a control model with strength being first strong and then weak, adopting larger air supply strength of 150-200NL/min in the early stage of soft blowing, blowing larger slag hole on the surface of the slag, and then keeping the argon blowing strength at 50-100NL/min in the second stage to ensure that the surface of the slag layer slightly creeps.

Further, the refining slag control process comprises the following steps: the refining furnace slag-making agent is lime and fluorite, the addition amount of the lime is 5-6 kg/ton steel, the addition amount of the fluorite is 1-2 kg/ton steel, oxygen in silicon carbide slag removal is adopted, the addition amount is 1.5 kg/ton steel, the condition of slag is observed through dipping a slag sample at any time in the smelting process, and the white slag time is kept to be more than or equal to 8min before the refining furnace is out of position.

Further, the VD soft blowing process control specifically comprises the following steps:

keeping the deep vacuum degree below 30Pa, and keeping the deep vacuum time for 15 min; soft blowing is kept for 15min after deep vacuum breaking, and the two stages are divided, wherein the argon blowing strength is 150-200NL/min in 10min in the first stage, so that a large slag hole is formed on the slag surface; the second stage is performed at 5min argon blowing intensity of 50-100 NL/min.

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

1) the method adopts an innovative inclusion control theory and provides a technical route for removing the inclusions by accurately controlling the components of the inclusions for the first time;

2) the method defines key control technical parameters, is easy to popularize and implement and can ensure the implementation effect.

Drawings

FIG. 1 is a schematic diagram of a soft blow first stage;

fig. 2 is a schematic diagram of the second stage of soft blowing.

Detailed Description

A control method for effectively controlling inclusion components of heavy rail steel comprises the following steps:

1) the deoxidizer is silicon-calcium-barium, the components of the deoxidizer are required to be more than or equal to 50% of Si, more than or equal to 13% of Ca, more than or equal to 14% of Ba, more than or equal to 28% of Ca + Ba, less than or equal to 0.05% of P and less than or equal to 0.10% of S, and the alloy is low-aluminum silicon iron, silicon-manganese and the like. The content of residual aluminum and calcium in the alloy and the deoxidizer is strictly limited, the content of residual Al is required to be less than or equal to 1 percent, the content of residual Ca is required to be less than 0.5 percent, and the content of calcium in silicon, calcium and barium is not limited by the specification;

2) the total amount of residual aluminum and residual calcium brought in by the alloy or deoxidizer is strictly controlled according to the oxygen content in the primary steel. The amounts of Si, Ca and Ba added according to 1) can be determined according to the following table:

3) controlling key indexes of refining slag, wherein the viscosity R is required to be between 1.8 and 2.1, Al2O3 in the slag is less than 5 percent, and MgO is less than 8 percent;

4) preferably, the argon blowing control model of the VD soft blowing process adopts a control model with strength being first strong and then weak, the larger air supply strength of 150-200NL/min is adopted in the early stage of soft blowing, and a larger slag hole is blown on the surface of the slag, which has larger difference with the common soft blowing control requirement, mainly because the rail steel inclusion is liquid inclusion in the VD procedure, and the dynamic condition is not satisfied when the small soft blowing flow is adopted. Then, in the second stage, the argon blowing intensity is kept at 50-100NL/min, and the slight creeping of the surface of the slag layer is observed, and the main purpose is to promote the separation of the molten steel and the slag.