Piston steel smelting method for replacing electroslag remelting

Abstract

The invention discloses a piston steel smelting method for replacing electroslag remelting, which comprises an electric furnace optimizing process and a refining process, and comprises the following steps: (1) aiming at a 100t electric furnace, adjusting the adding amount of lime and synthetic slag according to whether the content of C at a tapping end point is more than or equal to 0.08%, and when the tapping amount reaches 20-50t, starting furnace rear alloying and deoxidation; (2) designing a special refining slag system according to the oxidizability of the electric furnace, and adding 400 + / -20kg of lime and 600 + / -20kg of synthetic slag; and (3) before vacuum treatment, the feeding amount of the pure calcium rod core-spun yarn is adjusted according to whether the Al content is 0.030%-0.035% or not. The method has the advantages that the purity of molten steel is guaranteed, the tapping oxygen level of the molten steel is improved, the control stability and adsorption capacity of a refining slag system are improved, floating of inclusions is accelerated through calcium treatment, cost is saved, and mass production is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a smelting method for piston steel that replaces electroslag remelting. Background Art

[0002] As a special metallurgical technology, electroslag remelting is mainly used for products with extremely high requirements for inclusions, such as bearing steel, mold steel, and stainless steel. Through the electroslag remelting technology, molten droplets are formed and contacted with slag. First, non-metallic inclusions will decompose during the high-temperature electrode process, and the slag will react and enter the slag layer; second, through the design and adjustment of the slag system, the molten droplets will undergo a series of chemical reactions with Al, Ca, Mg, etc. in the slag when passing through the slag layer, thereby reducing the inclusions in the molten droplets; finally, after passing through the slag layer, small particle inclusions will continuously float up and agglomerate due to their small size and low density, and then reach the slag interface, thereby improving the purity of the molten steel.

[0003] The main reason why electroslag remelting steel is difficult to produce through EOF-LF-VD(RH)-CC is that the entire production process is long, and there are too many factors affecting the purity of molten steel, such as slag rolling, slag system fluctuations, deoxidation process, vacuum process, etc. during the steelmaking process, which leads to excessive content of Ca-Al, Mg-Al, Ca-Mg-Al and other series of inclusions in the molten steel, making it difficult to maintain a high level of molten steel purity. At the same time, the electroslag remelting process is a secondary refining and purification of the ingot, which increases the production process cost of this type of steel. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of low purity, high production cost and inclusions in the existing molten steel, and to provide a smelting method for piston steel that can replace electroslag remelting, which can ensure the purity of molten steel, improve the oxygen level of molten steel, control stability and adsorption capacity of the refined slag system, accelerate the floating of inclusions through calcium treatment, save costs and facilitate mass production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A smelting method for piston steel replacing electroslag remelting, comprising optimizing an electric furnace process and a refining process, wherein the refining process is followed by a VD process and a continuous casting process, specifically: (1) For a 100t electric furnace, the amount of lime and synthetic slag added is adjusted according to whether the C content at the end of steel tapping is ≥0.08%. When the steel tapping volume reaches 20-50t, post-furnace alloying and deoxidation are started; (2) According to the oxidizability of the electric furnace, a special refining slag system is designed, and the added amounts are: lime 400±20kg, synthetic slag 600±20kg; (3) Before vacuum treatment, adjust the feeding amount of pure calcium rod cored wire according to whether the Al content is between 0.030% and 0.035%.

[0006] Furthermore, in the step (1), if the C content at the steel tapping end point is ≥ 0.08%, the amount of lime added is 380 kg to 400 kg, and the amount of synthetic slag added is 580 kg to 600 kg.

[0007] Furthermore, in the step (1), if the C content at the steel tapping end point is less than 0.08%, the amount of lime added is 400kg-420kg, and the amount of synthetic slag added is 600kg-620kg.

[0008] Furthermore, in step (3), if the Al content in the molten steel is ≥ 0.035%, 30-40 m of pure calcium rod cored wire is fed into the VD process.

[0009] Furthermore, in step (3), if the Al content in the molten steel is between 0.030% and 0.035%, 40 to 50 m of pure calcium rod cored wire is fed into the VD process.

[0010] Furthermore, in step (3), if the Al content in the molten steel is less than 0.030%, 50-60 m of pure calcium rod cored wire is fed into the VD process.

[0011] In the technical solution of the present invention, the purity of molten steel is stabilized and improved by optimizing the electric furnace steel-making process, the refining slag system control process, and the deoxidation process, and the reducing atmosphere of the refining process is continuously maintained. The ultimate vacuum degree of vacuum treatment is low, the slag washing effect is significant, and the produced products can also meet the purity requirements of this type of steel and achieve mass production. DETAILED DESCRIPTION Example 1

[0012] In order to make the present invention more clear, a smelting method for piston steel that replaces electroslag remelting of the present invention is further described below. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0013] Before using the smelting method of the present invention, a traditional process was used as a comparative example, and its process path included electric furnace-refining furnace-VD furnace-continuous casting.

[0014] (1) Electric furnace process: tapping temperature 1650℃, tapping carbon 0.09%, adding 400kg lime and 600kg synthetic slag at the end of tapping; (2) Refining process: After smelting for 66 minutes, the Al content in the molten steel is 0.029%. After feeding 30m of pure calcium rod cored wire, it enters the VD process; (3) VD process: vacuum degree 0.54 mbar, maintained for 20 minutes before breaking the vacuum, static stirring for 40 minutes before continuous casting; (4) Continuous casting process: 320*480 section, casting speed 0.51m / min.

[0015] In the present invention, a piston steel smelting method is provided to replace electroslag remelting, and the process path also includes electric furnace-refining furnace-VD furnace-continuous casting, which is characterized by: (1) Electric furnace process: steel tapping temperature 1660℃, steel tapping carbon 0.07%, 420kg lime and 620kg synthetic slag are added at the end of the steel tapping process.

[0016] (2) Refining process: After smelting for 65 minutes, the Al content in the molten steel is 0.024%. After feeding 60m of pure calcium rod cored wire, it enters the VD process.

[0017] (3) VD process: vacuum degree 0.65 mbar, maintain for 20 min before breaking the vacuum, static stirring for 51 min before continuous casting.

[0018] (4) Continuous casting process: 320*480 section, casting speed 0.51m / min. Example 2

[0019] In this embodiment, a piston steel smelting method is provided to replace electroslag remelting, wherein the process path includes electric furnace-refining furnace-VD furnace-continuous casting, and is characterized in that: (1) Electric furnace process: steel tapping temperature 1642℃, steel tapping carbon 0.10%, 390kg lime and 590kg synthetic slag are added at the end of the steel tapping process.

[0020] (2) Refining process: After smelting for 57 minutes, the Al content in the molten steel is 0.036%. After feeding 30m of pure calcium rod cored wire, it enters the VD process.

[0021] (3) VD process: vacuum degree 0.63 mbar, maintained for 20 min before breaking the vacuum, static stirring for 39 min before continuous casting.

[0022] (4) Continuous casting process: 320*480 section, casting speed 0.51m / min. Example 3

[0023] In this embodiment, a piston steel smelting method is provided to replace electroslag remelting, wherein the process path includes electric furnace-refining furnace-VD furnace-continuous casting, and is characterized in that: (1) Electric furnace process: steel tapping temperature 1635℃, steel tapping carbon 0.11%, 380kg lime and 580kg synthetic slag are added at the end of the steel tapping process.

[0024] (2) Refining process: After smelting for 62 minutes, the Al content in the molten steel is 0.032%. After feeding 40m pure calcium rod cored wire, it enters the VD process.

[0025] (3) VD process: vacuum degree 0.67 mbar, maintain for 20 minutes before breaking the vacuum, static stirring for 48 minutes before continuous casting.

[0026] (4) Continuous casting process: 320*480 section, casting speed 0.51m / min. Example 4

[0027] In this embodiment, a piston steel smelting method is provided to replace electroslag remelting, wherein the process path includes electric furnace-refining furnace-VD furnace-continuous casting, and is characterized in that: (1) Electric furnace process: steel tapping temperature 1635℃, steel tapping carbon 0.065%, 420kg lime and 620kg synthetic slag are added at the end of the steel tapping process.

[0028] (2) Refining process: After smelting for 62 minutes, the Al content in the molten steel is 0.037%. After feeding 50m of pure calcium rod cored wire, it enters the VD process.

[0029] (3) VD process: vacuum degree 0.52 mbar, maintain for 20 minutes and then break the vacuum, stir for 35 minutes and then start continuous casting.

[0030] (4) Continuous casting process: 320*480 section, casting speed 0.51m / min.

[0031] On the basis of the existing technology of the steel plant, the electric furnace steel-making process, the refining slag control process and the deoxidation process were optimized to achieve the continuous maintenance of the reducing atmosphere in the refining process, the low ultimate vacuum degree of the vacuum treatment, the significant slag washing effect and the improved purity of the molten steel.

[0032] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A method for smelting piston steel instead of electroslag remelting, comprising optimizing an electric furnace process and a refining process, wherein the refining process is followed by a VD process and a continuous casting process, and is characterized in that: (1) For a 100t electric furnace, the amount of lime and synthetic slag added is adjusted according to whether the C content at the end of steel tapping is ≥0.08%. When the steel tapping volume reaches 20-50t, post-furnace alloying and deoxidation are started; (2) According to the oxidizability of the electric furnace, a special refining slag system is designed, and the added amounts are: lime 400±20kg, synthetic slag 600±20kg; (3) Before vacuum treatment, adjust the feeding amount of pure calcium rod cored wire according to whether the Al content is between 0.030% and 0.035%.

2. The method for smelting piston steel by replacing electroslag remelting according to claim 1 is characterized in that: In the step (1), if the C content at the steel tapping end point is ≥ 0.08%, the amount of lime added is 380 kg to 400 kg, and the amount of synthetic slag added is 580 kg to 600 kg.

3. The method for smelting piston steel by replacing electroslag remelting according to claim 1 is characterized in that: In the step (1), if the C content at the steel tapping end point is less than 0.08%, the amount of lime added is 400kg-420kg, and the amount of synthetic slag added is 600kg-620kg.

4. The method for smelting piston steel by replacing electroslag remelting according to any one of claims 1 to 3, characterized in that: In the step (3), if the Al content in the molten steel is ≥ 0.035%, 30-40 m of pure calcium rod cored wire is fed into the VD process.

5. The method for smelting piston steel by replacing electroslag remelting according to any one of claims 1 to 3, characterized in that: In the step (3), if the Al content in the molten steel is between 0.030% and 0.035%, 40 to 50 m of pure calcium rod cored wire is fed into the VD process.

6. The method for smelting piston steel by replacing electroslag remelting according to any one of claims 1 to 3, characterized in that: In the step (3), if the Al content in the molten steel is less than 0.030%, 50-60 m of pure calcium rod cored wire is fed into the VD process.