Smelting method of Mn13 wear-resistant steel

Abstract

The invention discloses a smelting method of Mn13 wear-resistant steel, and belongs to the technical field of special steel smelting. The method comprises the following steps: (1) dephosphorizing a ladle; (2) the dephosphorized molten iron is added into an AOD converter to be subjected to decarburization and reduction treatment, and alloying of manganese is not conducted in the process; (3) tapping to a steel ladle and slagging off; (4) adding electrolytic manganese pre-melted in the intermediate frequency furnace into a steel ladle; (5) LF refining; and (6) continuous casting. According to the method, the alloying procedure of manganese is transferred to the subsequent procedure from the AOD furnace, decarburization is only focused in AOD, the problem that decarburization is inhibited due to the fact that the content of manganese oxide in slag is increased due to the fact that a large amount of manganese alloy is added into the AOD furnace is solved, and therefore the decarburization efficiency is remarkably improved, the smelting period is shortened, and meanwhile the heating aluminum consumption is reduced. And the intermediate frequency furnace is adopted to pre-melt electrolytic manganese, so that the yield of manganese is improved. And by utilizing equipment for smelting stainless steel, trace Cr can be brought in, so that the production cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of special steel smelting technology, specifically relating to a smelting method for Mn13 wear-resistant steel. Background Technology

[0002] Mn13 steel is a typical high-manganese wear-resistant steel. Due to its excellent work hardening ability and wear resistance under high impact and high wear conditions, it is widely used in key wear-resistant components in mining, building materials, engineering machinery and other fields.

[0003] Currently, the main smelting processes for Mn13 steel include the following: Electric arc furnace (EAF) - LF refining - continuous casting (CC) process: This process has problems such as long smelting cycle, difficulty in electric furnace decarburization, and easy splashing during the decarburization process, which pose safety risks. Medium frequency furnace-LF-CC process: This process has strict requirements for raw materials. Since medium frequency furnaces cannot effectively decarbonize, low-carbon materials must be used, resulting in high production costs. Dephosphorization converter-AOD-LF-continuous casting process: This process requires the addition of manganese alloy in the AOD step, but the addition of manganese will increase the manganese oxide (MnO) content in the slag, inhibit the decarburization reaction, reduce the decarburization efficiency, and prolong the smelting cycle.

[0004] Therefore, developing an efficient, economical, and safe method for smelting Mn13 wear-resistant steel is of great practical significance. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-efficiency, low-cost and safe smelting method for Mn13 wear-resistant steel.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for smelting Mn13 wear-resistant steel includes the following steps: (1) Dephosphorization of molten iron in ladle: Dephosphorization of molten iron in blast furnace is carried out in ladle to obtain pretreated molten iron; The composition of the pretreated molten iron, by mass percentage, is: C: 3.0~3.7%, Si: ≤0.10%, Mn: 0.10~0.20%, P≤0.010%, S: 0.04~0.06%.

[0007] (2) AOD converter treatment: The pretreated molten iron obtained in step (1) is added to the AOD converter for decarburization and reduction treatment to obtain AOD steel; no manganese alloy material is added during the AOD converter treatment process for manganese alloying. The AOD smelting process is carried out with argon blowing throughout, and aluminum reduction is used in the reduction stage. The slag basicity is controlled at 2.2~2.6. The composition of the AOD molten steel, by mass percentage, is as follows: C: 1.00~1.20%, Si: 0.30~0.80%, Mn: 0.10~0.20%, P≤0.010%, S≤0.002%, Al: 0.01~0.05%, Cr: 0.30~0.80%.

[0008] (3) Tapping and slag removal: Tapping the AOD molten steel obtained in step (2) into the ladle, and then removing the slag from the ladle; the tapping temperature is 1600~1650℃; the amount of slag in the ladle after slag removal is ≤50mm.

[0009] (4) Adding manganese liquid: Add the electrolytic manganese liquid that has been melted in the medium frequency furnace to the molten steel after slag removal in step (3); the mass percentage of Mn in the electrolytic manganese is ≥99.9%; the amount of electrolytic manganese liquid added is 120~150Kg per ton of molten steel.

[0010] (5) LF refining: The molten steel after adding electrolytic manganese in step (4) is subjected to LF refining treatment; the LF refining process includes: adding lime and fluorite to form slag, heating for 10~20 minutes, adjusting the composition and temperature of the molten steel, feeding calcium wire, and weakly blowing argon gas treatment.

[0011] (6) Continuous casting: The molten steel refined in step (5) is continuously cast to obtain Mn13 wear-resistant steel slab. The tundish temperature for continuous casting is 1425~1440℃, and the casting speed is 0.6~0.7 m / min.

[0012] The chemical composition of the obtained Mn13 wear-resistant steel slab, by mass percentage, is as follows: C: 1.00~1.20%, Si: 0.30~0.80%, Mn: 12.8~14.0%, P≤0.010%, S≤0.002%, Al: 0.01~0.05%, Cr: 0.30~0.80%.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Improved decarburization efficiency and shortened smelting cycle: This invention only performs decarburization and reduction in the AOD converter, without manganese alloying. This avoids the drastic impact of adding a large amount of cold electrolytic manganese on the molten pool temperature, ensuring the high-temperature environment required for the decarburization process and reducing the consumption of aluminum used for heating. More importantly, the absence of manganese ensures a low manganese oxide (MnO) content in the slag during the decarburization period, eliminating the inhibitory effect of MnO on the carbon-oxygen reaction, thereby significantly improving decarburization efficiency and effectively shortening the AOD smelting cycle.

[0014] 2. Improved manganese yield and reduced costs: This invention employs a method of pre-melting electrolytic manganese in a medium-frequency furnace and then adding the high-temperature manganese liquid into a steel ladle. Compared to adding cold ferromanganese or electrolytic manganese to AOD or LF, liquid addition significantly reduces manganese burn-off and volatilization, improves manganese yield, and reduces alloy costs.

[0015] 3. Improve the purity of molten steel: AOD converter uses aluminum as a reducing agent, which has a strong deoxidation ability and can effectively reduce the total oxygen content in molten steel, thereby improving the purity of the final molten steel.

[0016] 4. Further cost reduction by utilizing residual chromium: This invention utilizes an AOD furnace and ladle that have been used to smelt stainless steel for production. The residual chromium in the lining will be incorporated into the molten steel during the smelting process, resulting in 0.30~0.80% residual chromium in the finished steel. This can have a beneficial effect on the performance of the steel without increasing costs.

[0017] 5. Good process safety: It avoids the splashing problem caused by the violent carbon-oxygen reaction in the traditional EAF process, making production safer. Attached Figure Description

[0018] Figure 1 This is a process flow diagram of the smelting process of Mn13 wear-resistant steel of the present invention. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0020] like Figure 1 As shown, the core process route of the Mn13 wear-resistant steel smelting method of the present invention is as follows: dephosphorization of molten iron ladle → AOD decarburization / reduction (unalloyed manganese) → tapping and slag removal → adding electrolytic manganese molten in medium frequency furnace into the ladle → LF refining → continuous casting.

[0021] Example 1 (1) Dephosphorization of molten iron in ladle: Dephosphorization treatment is carried out on molten iron in ladle. The composition of molten iron after treatment (mass percentage) is: C: 3.0%, Si: 0.10%, Mn: 0.10%, P: 0.010%, S: 0.04%.

[0022] (2) AOD converter treatment: 68 tons of pretreated molten iron were added to the AOD converter along with 12 tons of clean scrap steel. Argon blowing was used throughout the process for decarburization and reduction. The slag basicity was controlled at 2.2 during the reduction period, and aluminum reduction was adopted. The composition (mass percentage) of the treated molten steel was: C: 1.00%, Si: 0.30%, Mn: 0.10%, P: 0.010%, S: 0.002%, Al: 0.01%, Cr: 0.30%.

[0023] (3) Tapping and slag removal: Tapping AOD molten steel to the ladle at 1600℃, and then removing slag at the slag removal station, controlling the amount of slag in the ladle to be 50mm, and the amount of molten steel after tapping is 76 tons.

[0024] (4) Adding electrolytic manganese: Add 9.2 tons of electrolytic manganese (Mn≥99.9%) that has been pre-melted in the medium frequency furnace into the ladle.

[0025] (5) LF refining: The mixed molten steel is hoisted to the LF furnace, 1000 kg of lime and 500 kg of fluorite are added to form slag, and the temperature is raised for 10 minutes. After adjusting the composition and temperature, 50 meters of calcium wire is fed in, and then argon is blown weakly for 15 minutes.

[0026] (6) Continuous casting: The refined molten steel is continuously cast at a ladle temperature of 1425℃ and a casting speed of 0.7 m / min to obtain Mn13 wear-resistant steel slab. Its composition (mass percentage) is: C: 1.00%, Si: 0.30%, Mn: 12.8%, P: 0.010%, S: 0.002%, Al: 0.01%, Cr: 0.30%.

[0027] Example 2 (1) Dephosphorization of molten iron in ladle: Dephosphorization treatment is carried out on molten iron in ladle. The composition of molten iron after treatment (mass percentage) is: C: 3.7%, Si: 0.08%, Mn: 0.20%, P: 0.008%, S: 0.06%.

[0028] (2) AOD converter treatment: 72 tons of pretreated molten iron were added to AOD and 13 tons of clean scrap steel were added. The slag basicity was controlled at 2.6. The composition (mass percentage) of the molten steel after treatment was: C: 1.20%, Si: 0.80%, Mn: 0.20%, P: 0.008%, S: 0.001%, Al: 0.05%, Cr: 0.80%.

[0029] (3) Tapping and slag removal: The tapping temperature is 1650℃, the slag amount after slag removal is 40mm, and the amount of molten steel after tapping is 80 tons.

[0030] (4) Adding electrolytic manganese: Add 11.6 tons of electrolytic manganese (Mn≥99.9%) that has been pre-melted in the medium frequency furnace into the ladle.

[0031] (5) LF refining: After slag formation, heat up for 20 minutes, otherwise the same as in Example 1.

[0032] (6) Continuous casting: Tundish temperature 1440℃, casting speed 0.6 m / min. Slab composition (mass percentage): C: 1.20%, Si: 0.80%, Mn: 14.0%, P: 0.008%, S: 0.001%, Al: 0.05%, Cr: 0.80%.

[0033] Example 3 (1) Dephosphorization of molten iron in ladle: Dephosphorization treatment is carried out on molten iron in ladle. The composition of molten iron after treatment (mass percentage) is: C: 3.3%, Si: 0.05%, Mn: 0.14%, P: 0.007%, S: 0.05%.

[0034] (2) AOD converter treatment: 70 tons of pretreated molten iron were added to AOD and 12 tons of clean scrap steel were added. The slag basicity was controlled at 2.3. The composition (mass percentage) of the molten steel after treatment was: C: 1.10%, Si: 0.50%, Mn: 0.13%, P: 0.007%, S: 0.0015%, Al: 0.03%, Cr: 0.50%.

[0035] (3) Tapping and slag removal: The tapping temperature is 1620℃, the slag amount after slag removal is 45mm, and the amount of molten steel after tapping is 78 tons.

[0036] (4) Adding electrolytic manganese: Add 10.5 tons of electrolytic manganese (Mn≥99.9%) that has been pre-melted in the medium frequency furnace into the ladle.

[0037] (5) LF refining: After slag formation, heat up for 15 minutes, and the rest is the same as in Example 1.

[0038] (6) Continuous casting: Tundish temperature 1430℃, casting speed 0.65 m / min. Slab composition (mass percentage): C: 1.10%, Si: 0.50%, Mn: 13.5%, P: 0.007%, S: 0.0015%, Al: 0.03%, Cr: 0.50%.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Those skilled in the art should understand that various modifications and changes can be made to the above embodiments without departing from the spirit and scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for smelting Mn13 wear-resistant steel, characterized in that, Includes the following steps: (1) Dephosphorization of molten iron in ladle: Dephosphorization pretreatment is performed on molten iron in blast furnace in ladle to obtain pretreated molten iron; (2) AOD converter treatment: The pretreated molten iron obtained in step (1) is added to the AOD converter for decarburization and reduction treatment to obtain AOD steel; no manganese alloying is performed during the AOD converter treatment process; (3) Tapping and slag removal: Tapping the AOD molten steel obtained in step (2) into the ladle, and then removing the slag from the ladle; (4) Adding manganese liquid: Add the electrolytic manganese liquid that has been melted in the medium frequency furnace to the molten steel after slag removal in step (3); (5) LF refining: The molten steel after adding electrolytic manganese solution in step (4) is subjected to LF refining treatment; (6) Continuous casting: The molten steel refined in step (5) is continuously cast to obtain Mn13 wear-resistant steel slab.

2. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (1), the composition of the pretreated molten iron by mass percentage is: C: 3.0~3.7%, Si: ≤0.10%, Mn: 0.10~0.20%, P≤0.010%, S: 0.04~0.06%.

3. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (2), the AOD converter process is argon-blown throughout, the slag basicity is controlled at 2.2~2.6 during the reduction stage, and aluminum is used for reduction.

4. The smelting method for Mn13 wear-resistant steel according to claim 1 or 3, characterized in that, In step (2), the composition of the AOD molten steel by mass percentage is as follows: C: 1.00~1.20%, Si: 0.30~0.80%, Mn: 0.10~0.20%, P≤0.010%, S≤0.002%, Al: 0.01~0.05%, Cr: 0.30~0.80%.

5. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (3), the tapping temperature is 1600~1650℃; the amount of slag on the ladle after slag removal is ≤50mm.

6. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (4), the Mn content of electrolytic manganese is ≥99.9%, and the amount of electrolytic manganese liquid added is 120~150Kg / t of molten steel.

7. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (5), the LF refining includes: adding lime and fluorite to form slag, heating for 10-20 minutes, adjusting the composition and temperature of the molten steel, feeding in calcium wire and performing weak argon blowing treatment.

8. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, In step (6), the tundish temperature of continuous casting is 1425~1440℃, and the casting speed is 0.6~0.7 m / min.

9. The smelting method of Mn13 wear-resistant steel according to claim 1, characterized in that, The composition of the Mn13 wear-resistant steel slab obtained in step (6) by mass percentage is as follows: C: 1.00~1.20%, Si: 0.30~0.80%, Mn: 12.8~14.0%, P≤0.010%, S≤0.002%, Al: 0.01~0.05%, Cr: 0.30~0.80%.

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