阅读说明：本技术 一种rh高效冶炼的方法 (RH high-efficiency smelting method ) 是由 谢鑫 张敏 吴晨辉 白旭旭 于 2021-10-12 设计创作，主要内容包括：本发明提供了一种RH高效冶炼的方法,包括：钢包到达RH工位,采用两个底吹氩气孔软吹氩气；插入管进入钢液后,钢包以顺时针或逆时针的方向旋转。本发明采用钢包旋转的方式,减少死区,加快钢液的循环,减少RH处理时间,可在国内同行业推广应用。(The invention provides a method for RH high-efficiency smelting, which comprises the following steps: when the steel ladle reaches an RH station, soft argon blowing is carried out by adopting two bottom argon blowing air holes; after the insertion tube enters the molten steel, the ladle rotates in a clockwise or counterclockwise direction. The invention adopts the ladle rotation mode, reduces dead zones, quickens the circulation of molten steel, reduces RH processing time, and can be popularized and applied in the same industry in China.)

1. An RH high-efficiency smelting method comprises the following steps:

the ladle reaches the RH station, and after the insertion tube enters molten steel, the ladle rotates in a clockwise or anticlockwise direction.

2. The method of claim 1, wherein the molten steel composition in the ladle is selected from the group consisting of heavy rail steel and low carbon steel.

3. The method of claim 1, wherein the ladle further comprises, after reaching the RH station:

soft blowing argon by adopting two bottom blowing argon holes;

the flow rate of the soft argon blowing is 100-150L/min.

4. The method of claim 1, wherein the insertion tube has a diameter of 400-700 mm.

5. The method of claim 1, wherein the depth of the insertion tube into the molten steel is 400-600 mm.

6. The method of claim 1, wherein the speed of the rotation is 0.1 to 6 r/min.

7. The method according to claim 1, wherein the initial speed is 0.1r/min during the rotation process, the speed is gradually increased, and the rotation speed is rotated at a stable speed after 5-10 min reaches a preset speed.

8. The method according to claim 1, wherein the ladle is rotated to the initial position to stop moving at the later RH smelting stage in the rotating process, and RH processing is waited for to be finished.

9. The method according to claim 8, wherein in the later stage of RH smelting, for 1-3 min, the ladle is slowly decelerated, rotated to the initial position, stopped moving and waits for RH treatment to be finished.

10. The method according to claim 9, wherein after the movement is stopped, RH is continuously processed for 1-2 min before tapping.

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to an RH efficient smelting method.

Background

The refining apparatus RH of a steel plant has functions of decarburization, degassing (H, N), deoxidation, inclusion removal, component uniformization, temperature, and the like, is technically mature, can perform continuous operation stably in batches, and has been an important means for producing high-grade steel. These high-grade steels have a narrow composition control range and require deep decarburization and degassing. However, the RH treatment time must be matched to the continuous casting time, and the RH treatment efficiency needs to be improved.

After the steel ladle carries the molten steel to reach the RH station, an RH ascending pipe and a descending pipe are inserted into the molten steel, then the molten steel is driven to move to a vacuum chamber from the ascending pipe through vacuumizing and argon blowing by the ascending pipe, and the molten steel returns to the steel ladle from the descending pipe after metallurgical treatment, as shown by an arrow in figure 2. Because the movement route of the molten steel is fixed, the decarburization, the deoxidation and the operation of uniform alloy components of the molten steel are required to be gradually carried out through molten steel convection and element diffusion, namely, the improvement of the molten steel flow is an important index of RH efficiency. However, there are significant dead zones away from the region of the insertion tube (regions C and D in the top view of fig. 2), which affect the RH processing efficiency.

At present, RH mainly achieves the purposes of improving the flow of molten steel and increasing the RH efficiency by increasing the vacuum degree, increasing the diameter of an insert pipe, changing the insert pipe into an ellipse and increasing the argon blowing amount of a rising pipe. However, these operations have limitations. For example, increasing the vacuum degree increases the investment of equipment modification, and the vacuum degree approaches the limit; the diameter of the insertion pipe is increased, and the reasonable wall thickness of the insertion pipe and the stable operation of inserting molten steel are considered under the influence of the diameter of the steel ladle; the shape of the insertion pipe is changed into an ellipse, so that the lifting flow of the molten steel is increased less, but the ellipse is inconvenient to construct and maintain; the ascending pipe erosion aggravates due to the increase of the argon blowing quantity, and the lifting flow is saturated after the argon blowing flow reaches a certain degree.

The molten steel circulation efficiency is insufficient, so that the impurity removal rate at the early stage of RH is low; if the inclusions are not sufficiently removed before the titanium is added, more titanium-aluminum composite inclusions can appear after the titanium is added, the inclusions are not favorably removed, and the problems of water gap blockage and the like can be caused.

In addition, the argon blowing from the bottom of the steel ladle enhances the stirring effect of the molten steel and is an effective means for improving the RH treatment efficiency. But the bottom blowing position is fixed, so the stirring effect on the molten steel is not good. Bottom blowing below the downcomer can also produce a barrier effect on the downward flow of molten steel, which is not favorable for RH efficient treatment.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for RH high-efficiency smelting, which has a high RH treatment efficiency.

The invention provides a method for RH high-efficiency smelting, which comprises the following steps:

the ladle reaches the RH station, and after the insertion tube enters molten steel, the ladle rotates in a clockwise or anticlockwise direction.

Preferably, the molten steel in the ladle is selected from gravity rail steel or low-carbon steel.

The ladle still includes after reaching the RH station:

soft blowing argon by adopting two bottom blowing argon holes;

preferably, the flow rate of the soft argon blowing is 100-150L/min.

Preferably, the diameter of the insertion tube is 500-700 mm.

Preferably, the depth of the insertion pipe entering molten steel is 500-600 mm.

Preferably, the rotating speed is 0.1-6 r/min.

Preferably, the initial speed in the rotation process is 0.1r/min, the rotation speed is gradually accelerated, and the rotation speed is rotated at a stable speed after the rotation speed reaches a preset speed within 5-10 min.

Preferably, in the later RH smelting period in the rotating process, the ladle rotates to the initial position to stop moving, and RH treatment is waited to be finished.

Preferably, in the later stage of RH smelting, the steel ladle is slowly decelerated, rotated to the initial position, stopped moving and waits for RH treatment to be finished after 1-3 min.

Preferably, after the movement is stopped, the RH is continuously treated for 1-2 min, and then tapping is carried out.

The invention adopts the ladle rotation mode, reduces dead zones, quickens the circulation of molten steel, reduces RH processing time, and can be popularized and applied in the same industry in China. Furthermore, the method provided by the invention changes the dead zone of molten steel movement in the steel ladle by the rotation of the steel ladle and the change of the argon blowing position, thereby improving the treatment efficiency of RH decarburization, deoxidation, uniform components and inclusion floating.

Drawings

FIG. 1 is a schematic three-dimensional structure of an RH smelting device;

FIG. 2 is a front view and a top view of an RH smelting device in the embodiment of the present invention;

fig. 3 is a schematic view of the rotating direction of the ladle in the embodiment of the invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, 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 examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.

The invention provides a method for RH (molten steel vacuum treatment technology) high-efficiency smelting, which comprises the following steps:

the ladle reaches the RH station, and after the insertion tube enters molten steel, the ladle rotates in a clockwise or anticlockwise direction.

Fig. 1 shows a schematic three-dimensional structure of an RH device according to the present invention.

The invention has no special limitation on the components of the molten steel in the ladle, and a person skilled in the art can smelt the molten steel with required components according to the actual situation. In the invention, the molten steel in the ladle can be heavy rail steel or low carbon steel and ultra-low carbon steel. In the present invention, the molten steel composition of the heavy rail steel preferably includes:

0.71-0.80 wt% of C;

0.5 to 0.8 wt% of Si;

0.7 to 1.05 wt% Mn;

0.04-0.12 wt% of V;

the balance being Fe.

In the invention, the mass content of C is preferably 0.73-0.77%, more preferably 0.75%; the mass content of Si is preferably 0.6-0.7%, and more preferably 0.65%; the mass content of Mn is preferably 0.8-1.0%, and more preferably 0.9%; the mass content of V is preferably 0.05-0.1%, more preferably 0.06-0.09%, and most preferably 0.07-0.08%.

In the present invention, the ultra-low carbon steel liquid preferably comprises the following components:

0.002-0.004 wt% of C;

0.01 to 0.03 wt% of Si;

0.1 to 0.25 wt% Mn;

0.05-0.075 wt% of Ti;

0.03-0.06 wt% of Al;

the balance being Fe.

In the present invention, the mass content of C is preferably 0.003%; the mass content of Si is preferably 0.02%; the mass content of Mn is preferably 0.15-0.2%, more preferably 0.16-0.18%; the mass content of Ti is preferably 0.06-0.07%, and more preferably 0.065%; the mass content of Al is preferably 0.04-0.05%.

In the invention, after the ladle reaches the RH station, the method further comprises the following steps:

two bottom blowing argon holes are adopted for soft blowing argon.

In the invention, the flow rate of the soft argon blowing is preferably 100-150L/min, more preferably 110-140L/min, and most preferably 120-130L/min.

In the present invention, the diameter of the insertion tube is preferably 400 to 700mm, more preferably 500 to 600mm, and most preferably 550 mm.

In the invention, the depth of the insertion pipe entering the molten steel is preferably 400-600 mm, more preferably 450-550 mm, and most preferably 500 mm.

In the present invention, during the rotation process, it is preferable that the ladle is driven by the rotating device of the base to slowly rotate in the direction of ADBC clockwise or ACBD counterclockwise, as shown in fig. 3.

In the invention, the rotating speed is preferably 0.1-6 r/min, more preferably 0.5-5 r/min, more preferably 1-4 r/min, and most preferably 2-3 r/min.

In the invention, the initial speed is preferably 0.1r/min in the rotating process, the rotation speed is gradually accelerated, and the rotation speed is rotated at a stable speed after 5-10 min reaches a preset speed, more preferably 6-9 min, and most preferably 7-8 min.

According to the RH smelting processing rhythm, in the later stage of RH smelting, the ladle rotates to the initial position to stop moving, and the RH processing is waited to be finished, wherein the later stage of RH smelting is a pure circulation period after alloying.

In the invention, the ladle is preferably slowly decelerated to rotate to the initial position and stop moving in the later RH smelting period of 1-3 min, and the RH treatment is waited to be finished, more preferably 1.5-2.5 min, and most preferably 2 min.

In the invention, after the ladle stops moving, RH is preferably continuously treated for 1-2 min and then tapping is carried out, and more preferably for 1.5 min.

In the present invention, the method for RH smelting (or treating) preferably includes:

firstly, vacuumizing, decarbonizing or degassing, preparing alloy, circulating, breaking empty and taking out.

In the present invention, the evacuation is preferably 50Pa or less, more preferably 30Pa or less.

The method provided by the invention changes the dead zone of molten steel movement in the steel ladle by the rotation of the steel ladle and the change of the argon blowing position, thereby improving the treatment efficiency of RH decarburization, deoxidation, uniform components and inclusion floating. The invention adopts the ladle rotation mode, reduces dead zones, quickens the circulation of molten steel, reduces RH processing time, and can be popularized and applied in the same industry in China.

In the following embodiments of the invention, the molten steel in the ladle comprises the following components:

steel grade

C，wt％

Si，wt％

Mn，wt％

V，wt％

Ti，wt％

Als，wt％

Balance of

Heavy rail steel U75V

0.71～0.80

0.5～0.8

0.7～1.05

0.04～0.12

0

0

Fe

IF steel of ultra-low carbon steel

0.003

0.02

0.1～0.25

0

0.05～0.075

0.03～0.06

Fe

The schematic structural diagram of the ladle adopted in the RH smelting process is shown in figure 2.

Example 1120 t ladle to produce heavy Rail Steel

The steel ladle reaches an RH station, and RH starts normal treatment operation after an insert tube (the diameter is 550mm, the insert depth is 500mm) enters molten steel; the ladle drives the ladle to slowly rotate in the direction of ADBC (as shown in figure 3) through a rotating device of the base; the initial speed of the ladle rotation is 0.1r/min, the steel ladle is gradually accelerated, and the steel ladle stably rotates after reaching the set speed of 6r/min after 5 minutes;

in the later stage of RH treatment for 3min, slowly decelerating the steel ladle, rotating to the initial position, stopping movement, and tapping after RH treatment is continued for 1 min;

the specific method of RH treatment comprises the following steps: vacuumizing to less than or equal to 50Pa, degassing, mixing with gold, circulating, breaking, and discharging.

After the RH treatment by the method provided by the embodiment 1 of the invention, the C-type inclusion in the heavy rail rolled material is 0.5 grade, and the H content of RH ex-station is 0.8 ppm.

According to the method provided by the embodiment 1 of the invention, the degassing time is 14min, the homogenization time after alloying is 7min, and the total RH treatment time is 24 min.

Example 2210 t ladle, production of ultra-low carbon steel

The steel ladle reaches an RH station, and RH starts normal treatment operation after an insert tube (the diameter is 550mm, the insert depth is 500mm) enters molten steel; the ladle drives the ladle to slowly rotate in the direction of the ACBD (shown in figure 3) through a rotating device of the base; the initial speed of the ladle rotation is 0.1r/min, the steel ladle is gradually accelerated, and the steel ladle stably rotates after reaching the set speed of 3r/min after 5 minutes;

and in the later stage of RH treatment for 4min, slowly decelerating the ladle, rotating to the initial position, stopping moving, and tapping after RH treatment is continued for 1 min.

The specific method of RH treatment comprises the following steps: vacuumizing to less than or equal to 30Pa, decarbonizing, matching with gold, circulating, breaking empty, and taking out.

After the RH treatment by the method provided by the embodiment 2 of the invention, the carbon content of the obtained finished product is 19ppm, and the degradation rate of the inclusion of the rolled material is 14%.

According to the method provided by the embodiment 2 of the invention, the decarburization time is 19min, the homogenization time after alloying is 6min, and the total RH treatment time is 30 min.

Example 3120 t ladle, heavy rail steel was produced.

When the steel ladle reaches the RH station, soft argon blowing is started by adopting two bottom argon blowing air holes, and the flow is 100L/min;

after the insertion pipe (with the diameter of 550mm) enters molten steel (the insertion depth is 500mm), RH starts normal processing operation, and the steel ladle drives the steel ladle to slowly rotate in the ADBC clockwise direction (as shown in figure 3) through a rotating device of the base; the initial speed of the ladle rotation is 0.1r/min, the steel ladle is gradually accelerated, and the steel ladle stably rotates after reaching the set speed of 6r/min after 5 minutes;

in the later stage of RH treatment for 3min, slowly decelerating the steel ladle, rotating to the initial position, stopping movement, and tapping after RH treatment is continued for 1 min;

the specific method of RH treatment comprises the following steps: vacuumizing to less than or equal to 50Pa, degassing, adding ferrovanadium, ferromanganese and other alloy, circulating, breaking, and discharging.

After the RH treatment by the method provided by the embodiment 3 of the invention, the C-type inclusion in the heavy rail rolled material is 0.5 grade, and the H content of RH discharged station is 1.2 ppm.

According to the method provided by the embodiment 3 of the invention, the degassing time is 12.5min, the homogenization time after alloying is 5min, and the total RH treatment time is 20 min.

Example 4210 t ladle for producing ultra-low carbon steel

When the steel ladle reaches the RH station, soft argon blowing is started by adopting two bottom argon blowing air holes, and the flow is 150L/min;

after the insertion tube (with the diameter of 550mm) enters molten steel (the insertion depth is 500mm), RH starts normal processing operation, and the steel ladle drives the steel ladle to slowly rotate along the anticlockwise direction (shown in figure 3) of ACBD through a rotating device of the base; the initial speed of the ladle rotation is 0.1r/min, the steel ladle is gradually accelerated, and the steel ladle stably rotates after reaching the set speed of 3r/min after 5 minutes;

in the later stage of RH treatment for 4min, slowly decelerating the steel ladle, rotating to the initial position, stopping movement, and tapping after RH treatment is continued for 1 min;

the specific method of RH treatment comprises the following steps: firstly, vacuumizing to less than or equal to 30Pa, decarburizing, mixing with ferrosilicon, ferrotitanium and other alloys, circulating, breaking the space, and taking out of the station.

After the RH treatment by the method provided by the embodiment 4 of the invention, the carbon content of the obtained finished product is 20ppm, and the degradation rate of the inclusion of the rolled material is 13%.

In the method provided by the embodiment 4 of the invention, the decarburization time is 20min, the homogenization time after alloying is 5min, and the total RH treatment time is 31 min.

Comparative example 1120 t ladle, heavy Rail Steel production

When the steel ladle reaches the RH station, soft argon blowing is started (argon is started to be soft blown by two bottom argon blowing holes), and the flow is 100L/min;

after the insertion tube (with the diameter of 550mm) enters the molten steel (with the insertion depth of 500mm), RH starts normal treatment operation;

the specific method of RH treatment comprises the following steps: vacuumizing to less than or equal to 50Pa, degassing, mixing with gold, circulating, breaking, and discharging.

After RH treatment according to the method provided in comparative example 1 of the present invention, the C-type inclusions in the heavy rolled stock were 1.0 grade, and the RH off-site H content was 2 ppm.

According to the method provided by the comparative example 1, the degassing time is 15min, the homogenization time after alloying is 8min, and the total RH treatment time is 25.5 min; compared with comparative example 1, the degassing time of the RH treatment method provided in example 3 was shortened by 2.5min, and the homogenization time after alloying was reduced by 3 min; the total time of RH treatment is reduced by 5.5 min.

COMPARATIVE EXAMPLE 2210 t ladle for producing ultra-low carbon steel

When the steel ladle reaches the RH station, soft argon blowing is started (argon is started to be soft blown by two bottom argon blowing holes), and the flow is 150L/min;

after the insertion tube (with the diameter of 550mm) enters the molten steel (with the insertion depth of 500mm), RH starts normal treatment operation;

the specific method of RH treatment comprises the following steps: vacuumizing to less than or equal to 30Pa, decarbonizing, matching with gold, circulating, breaking empty, and taking out.

After the RH treatment by the method provided by comparative example 2 of the invention, the carbon content in the obtained finished product is 23ppm, and the degradation rate of the inclusion in the rolled material is 15%.

According to the method provided by comparative example 2, the decarburization time is 22.5min, the homogenization time after alloying is 7min, and the total RH treatment time is 35.5 min; compared with comparative example 2, in the RH treatment method provided in example 4, the decarburization time is shortened by 2.5min, and the homogenization time after alloying is reduced by 2 min; the total RH treatment time is reduced by 4.5 min.

According to the embodiment, the method provided by the invention changes the dead zone of molten steel movement in the steel ladle through the rotation of the steel ladle and the change of the argon blowing position, thereby improving the treatment efficiency of RH decarburization, degassing, uniform components and floating inclusion. The invention adopts the ladle rotation mode, reduces dead zones, quickens the circulation of molten steel, reduces RH processing time, and can be popularized and applied in the same industry in China.

While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.