A method of smelting an ultra-low manganese steel

Abstract

The application belongs to the technical field of ultra-low manganese steel, and discloses a smelting method of ultra-low manganese steel. The smelting method comprises the following steps: hot metal pretreatment, converter smelting, LF refining and RH refining. In the converter smelting, double-slag smelting is adopted, the time and temperature of the double slag are controlled, manganese is effectively removed, and manganese return is avoided. The bottom blowing flow is controlled in sections in the converter blowing and refining. In the early stage, large bottom blowing flow is used to promote manganese removal, and in the later stage, small bottom blowing flow is used to inhibit manganese return in the later stage. The temperature is controlled in the middle and later stages of blowing and refining, and the terminal temperature is controlled to reduce manganese return. Through the above process, the application can stably control the manganese content of the finished product to be less than or equal to 0.02%, and the process is simple and the production cost is low.

Description

Technical Field

[0001] This invention belongs to the field of ultra-low manganese steel technology, and specifically relates to a smelting method for ultra-low manganese steel. Background Technology

[0002] For most steel grades, manganese is a beneficial alloying element. However, with increasing manganese content, the electrical conductivity of steel decreases sharply, while resistivity increases. Simultaneously, manganese increases the coercivity of steel, while decreasing saturation magnetization, remanent magnetization, and permeability. Therefore, for some steel grades, such as industrial pure iron, silicon steel, and cable steel, manganese is a harmful element, and its content should be as low as possible. In recent years, with the rapid development of new energy vehicles, power, and aerospace industries, downstream users have increasingly higher requirements for the purity and performance of raw materials. To reduce the impact of manganese on magnetization and permeability, high-grade steels require an Mn content ≤0.02%. Consequently, many manufacturers have conducted research on the production of low-manganese steel.

[0003] Chinese patent CN112342455A discloses a method for smelting industrial pure iron. This method addresses key processes in the production of low-manganese steel using a converter-LF-RH-continuous casting billet process. It employs measures such as selecting low-manganese molten iron and low-manganese scrap steel, using pre-slag removal in the converter, low-temperature tapping, adding slag-forming agents after the furnace without alloying, and removing top slag with a slag remover after pre-stirring demanganese removal in the ladle furnace. These measures reduce the manganese content in the molten steel after the furnace to below 0.03% from 0.065%, meeting the manganese requirements of the finished low-manganese steel. While selecting low-manganese molten iron is beneficial for low-manganese steel smelting, the Mn content in the molten iron is limited by the ore raw materials. Controlling the Mn content requires rebuilding the ore stockpile, which is difficult to implement. Furthermore, during the refining process, the molten steel needs heating and slag-forming treatment. Reactions at the slag-steel interface can easily lead to manganese reversion in the molten steel. This method reduces manganese reversion in the slag by slag removal, increasing workload and cost, and is unsuitable for manufacturers without slag removal equipment.

[0004] Chinese patent CN108754060A discloses a method for producing low-manganese steel. Besides controlling the Mn content in molten iron, it primarily controls the converter smelting process, including controlling the converter blowing lance position in a low-high-low-low-high-low-low mode, controlling the oxygen supply intensity in a low-medium-medium-low-slightly-high-high mode, controlling the bottom blowing intensity in a strong-strong-strong-low-low-strong mode, and controlling the final temperature at 1670–1690℃. This method can stably produce cast billets with a finished manganese content ≤0.035%. While this method mainly relies on the converter for manganese removal, the high converter final temperature makes the manganese oxidation product (MnO) unstable at high temperatures. It readily undergoes a reduction reaction, entering the molten steel from the slag and causing manganese reversion, resulting in unstable manganese content control.

[0005] In summary, under the existing process and equipment conditions, the smelting of low-manganese steel, especially ultra-low-manganese steel with Mn content ≤0.02%, faces difficulties. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a smelting method for ultra-low manganese steel that addresses the shortcomings of the existing technology, and can achieve stable control of the manganese content of the finished product ≤0.02%, with simple process and low production cost.

[0007] To solve the technical problem proposed in this invention, this invention provides a method for smelting ultra-low manganese steel, the process of which includes: hot metal pretreatment → converter smelting → LF refining → RH refining.

[0008] In the above scheme, the Mn content of the molten iron before pretreatment is ≤0.30%, the P content is ≤0.12%, the S content is ≤0.03%, and the Si content is 0.2-0.8%.

[0009] In the above scheme, the hot iron pretreatment process includes pre-slag removal and post-slag removal. Pre-slag removal is the removal of blast furnace slag carried by the hot iron before pretreatment, and post-slag removal is the removal of desulfurization slag generated during pretreatment after pretreatment. The amount of residual slag in the hot iron ladle before entering the converter is controlled to be ≤2kg / t of hot iron.

[0010] In the above scheme, the S content of the molten iron after pretreatment is ≤0.001%.

[0011] In the above scheme, low-sulfur low-alloy scrap steel is added before blowing in the converter smelting process according to heat balance, and the S content of the low-sulfur low-alloy scrap steel is ≤0.01%.

[0012] In the above scheme, to maximize the removal of Mn from the converter molten steel and reduce manganese reversion in the later stages of blowing, a double-slag operation is performed in the converter blowing process for 250–280 seconds. The timing of the double-slag operation has a significant impact on manganese control. If the double-slag operation is performed too early, the initial slag formation will be poor, making slag removal difficult. This not only limits manganese removal but also increases costs due to the slag and iron produced. If the double-slag operation is performed too late, the molten pool temperature will rise, leading to manganese reversion and affecting manganese removal in the later stages of blowing.

[0013] Furthermore, the basicity of the double slag is 1.2 to 1.6 before the slag is removed, and the amount of double slag removed is 1 / 2 to 2 / 3 of the amount of slag.

[0014] Furthermore, to avoid high manganese return due to high slag temperature, the slag pouring temperature is controlled at 1350–1400℃.

[0015] Furthermore, in order to control the slag pouring temperature, pellet ore is added 30-50 seconds before the double slag operation for temperature adjustment, and the oxidizing properties in the early stage of blowing are increased to promote demanganese removal. The amount of pellet ore added is 15-25 kg / t steel.

[0016] In the above scheme, to avoid excessively high temperatures in the later stages of blowing, lime and pellet ore are added to form slag and adjust the temperature when the blowing time reaches 50-60%. The amount of pellet ore added is 5-10 kg / t steel.

[0017] In the above scheme, the converter final temperature is controlled at 1585-1620℃, and the final carbon content is ≤0.03%.

[0018] In the above scheme, the basicity of the converter slag is 2.5 to 3.0.

[0019] In the above scheme, the converter tapping process involves double slag blocking, namely slag blocking in the early stage of tapping and slag blocking at the end of tapping, to reduce the amount of slag going down the converter and control the slag thickness to ≤40mm.

[0020] In the above scheme, the converter bottom blowing adopts a strong-medium-weak mode, with the bottom blowing intensity in the early stage of blowing being 0.035~0.040 Nm. 3 / min / t, mid-term bottom blowing intensity is 0.030~0.035Nm 3 / min / t, with a later bottom blowing intensity of 0.020~0.025Nm. 3 / min / t, strong stirring is used in the early stage of blowing to promote slag formation and demanganese removal, while weak stirring is used in the later stage of blowing to reduce manganese return in slag.

[0021] In the above scheme, lime is added when the steel is tapped from the converter, at a rate of 1.5 to 3.5 kg / t of steel, without deoxidizing the slag and molten steel.

[0022] In the above scheme, the LF refining process only heats the molten steel, and neither the top slag nor the molten steel is deoxidized. After the temperature is raised to 1595-1605℃, the ladle is stirred with argon at medium intensity to promote the reaction of the steel slag and to demanganese by utilizing the high oxidizing properties of the molten steel and slag.

[0023] Furthermore, the argon flow rate is 400–600 L / min, and the stirring time is 5–10 min.

[0024] In the above scheme, the LF refining station temperature is controlled at 1600-1620℃.

[0025] In the above scheme, the RH refining station performs oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled between 0.5 and 1.5 m³. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure cycle treatment for 8-10 minutes after alloying.

[0026] In the above scheme, to avoid the top slag being reformed and reverting to manganese, the RH refining top slag is not subjected to reduction reforming.

[0027] In the above scheme, the Mn content in the molten steel obtained after RH refining is ≤0.02%, S content is ≤0.002%, P content is ≤0.005%, and total oxygen content (TO) is ≤0.003%.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1) This invention mainly adopts "deep manganese removal in converter smelting". The converter uses double-slag smelting, controls the timing of double slag removal, and adds an appropriate amount of coolant to control the temperature of the double slag, effectively removing manganese and avoiding manganese reversion. The bottom blowing flow rate is controlled in stages during converter blowing. The large flow rate in the early stage promotes manganese removal, while the small flow rate in the later stage inhibits manganese reversion. The heating rate and the final temperature are controlled in the middle and late stages of blowing to reduce manganese reversion. The slag amount is controlled by two levels when tapping the steel from the converter to reduce manganese reversion in the subsequent refining process. After the above process, the manganese content of the finished product can be stably controlled to ≤0.02%. The process is simple and the production cost is low.

[0030] 2) This invention can also be further combined with "LF refining to control manganese return and shallow demanganese removal" and "RH refining to remove manganese in appropriate amounts". In LF refining, the slag is not modified, and oxygen is supplied to the molten steel to remove some manganese during the heating process; RH refining blows oxygen into the molten steel to further remove manganese, and the top slag is not reduced to avoid manganese return. After the above process, the stable control of manganese content is further promoted. Detailed Implementation

[0031] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0032] The following embodiments of the present invention provide a method for smelting ultra-low manganese steel, comprising the following steps:

[0033] 1) Hot metal pretreatment

[0034] The hot metal pretreatment process includes pre-slag removal and post-slag removal, controlling the amount of residual slag in the hot metal ladle before entering the converter to be ≤2kg / t of hot metal, and the S content of the hot metal to be ≤0.001%;

[0035] 2) Converter smelting

[0036] a. Before blowing, add low-sulfur, low-alloy scrap steel with an S content ≤0.01% according to the heat balance.

[0037] b. The converter bottom blowing adopts a strong-medium-weak mode, with the bottom blowing intensity in the early stage of blowing being 0.035~0.040Nm. 3 / min / t, mid-term bottom blowing intensity is 0.030~0.035Nm 3 / min / t, with a later bottom blowing intensity of 0.020~0.025Nm. 3 / min / t;

[0038] c. During the converter blowing process, double slag operation is carried out for 250-280 seconds. 30-50 seconds before the double slag operation, pellet ore is added at an addition rate of 15-25 kg / t steel, and the slag pouring temperature is controlled at 1350-1400℃. The basicity before double slag operation is 1.2-1.6, and the amount of double slag poured is 1 / 2 to 2 / 3 of the slag amount.

[0039] d. When the blowing time reaches 50-60%, lime and pellet ore are added, with a pellet ore addition amount of 5-10 kg / t steel; the final converter temperature is controlled at 1585-1620℃, the final carbon content is ≤0.03%; the final converter slag basicity is 2.5-3.0.

[0040] e. Double slag blocking is used during converter tapping to control the slag thickness to ≤40mm;

[0041] f. When tapping steel from the converter, add lime at a rate of 1.5 to 3.5 kg / t of steel, without deoxidizing the slag and molten steel;

[0042] 3) LF Refining

[0043] The molten steel is heated to a temperature of 1595–1605℃. The ladle is then stirred with argon at a medium intensity, with an argon flow rate of 400–600 L / min and a stirring time of 5–10 min. The temperature at the station is controlled at 1600–1620℃.

[0044] 4) RH refining

[0045] The molten steel is subjected to oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled between 0.5 and 1.5 m³. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure recycling for 8-10 minutes; the top slag is not reduced or modified; the manganese content (Mn) in the molten steel obtained after refining is ≤0.02%.

[0046] Example 1

[0047] In this embodiment, the molten iron before pretreatment contains 0.30% Mn, 0.10% P, 0.02% S, and 0.8% Si.

[0048] The smelting method for ultra-low manganese steel in this embodiment includes the following steps:

[0049] 1) Hot metal pretreatment

[0050] The hot metal pretreatment process includes pre-slag removal and post-slag removal, controlling the amount of residual slag in the hot metal ladle to 2 kg / t of hot metal before it enters the converter, and the sulfur content of the hot metal to 0.0005%.

[0051] 2) Converter smelting

[0052] a. Before blowing, add low-sulfur, low-alloy scrap steel according to heat balance;

[0053] b. The converter bottom blowing adopts a strong-medium-weak mode, with a bottom blowing intensity of 0.040 Nm in the early stage of blowing. 3 / min / t, mid-term bottom blowing intensity is 0.035Nm 3 / min / t, the later bottom blowing intensity is 0.025Nm 3 / min / t;

[0054] c. During the 250s of converter blowing, double slag operation is carried out. 30s before the double slag operation, pellet ore is added at an addition rate of 25kg / t steel, and the slag pouring temperature is controlled at 1350℃. The slag basicity before double slag operation is 1.2, and the amount of double slag poured is 1 / 2 of the slag amount.

[0055] d. When the blowing time reaches 50%, lime and ore pellets are added, with an addition amount of 5 kg / t steel for the ore pellets; the final converter temperature is 1620℃, the final carbon content is 0.03%, and the final slag basicity is 2.8.

[0056] e. Double slag blocking is used when tapping steel from the converter to control the slag thickness at 40mm;

[0057] f. When tapping steel from the converter, lime is added at a rate of 3.5 kg / t of steel, without deoxidizing the slag and molten steel;

[0058] 3) LF Refining

[0059] The molten steel is heated to a temperature of 1595℃. Neither the top slag nor the molten steel is deoxidized. After the temperature is raised to 1595℃, the ladle is stirred by medium-intensity argon blowing at a flow rate of 400L / min for 5min. The temperature at the station is controlled at 1620℃.

[0060] 4) RH refining

[0061] The molten steel is subjected to oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled at 1.5 m³ / min. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure circulation treatment for 8 minutes after alloying; the top slag is not subjected to reduction modification.

[0062] In this embodiment, the molten steel obtained after RH refining has a Mn content of 0.015%, a S content of 0.0015%, a P content of 0.004%, and a total oxygen content (TO) of 0.0028%.

[0063] Example 2

[0064] In this embodiment, the molten iron before pretreatment contains 0.25% Mn, 0.12% P, 0.03% S, and 0.6% Si.

[0065] The smelting method for ultra-low manganese steel in this embodiment includes the following steps:

[0066] 1) Hot metal pretreatment

[0067] The hot metal pretreatment process includes pre-slag removal and post-slag removal to control the amount of residual slag in the hot metal ladle to 1.6 kg / t of hot metal before it enters the converter, and the sulfur content of the hot metal to 0.0007%.

[0068] 2) Converter smelting

[0069] a. Before blowing, add low-sulfur, low-alloy scrap steel according to heat balance;

[0070] b. The converter bottom blowing adopts a strong-medium-weak mode, with a bottom blowing intensity of 0.035 Nm in the early stage of blowing. 3 / min / t, mid-term bottom blowing intensity is 0.03 Nm 3 / min / t, the later bottom blowing intensity is 0.02Nm 3 / min / t;

[0071] c. During the 270s of converter blowing, double slag operation is carried out. 40s before the double slag operation, pellet ore is added at an addition rate of 20kg / t steel, and the slag pouring temperature is controlled at 1370℃. The slag basicity before double slag operation is 1.6, and the amount of double slag poured is 2 / 3 of the slag amount.

[0072] d. When the blowing time reaches 60%, lime and ore pellets are added, with an addition amount of 7 kg / t steel for each ore pellet; the final converter temperature is 1600℃, the final carbon content is 0.026%, and the final converter slag basicity is 3.0.

[0073] e. Double slag blocking is used when tapping steel from the converter to control the slag thickness at 40mm;

[0074] f. When tapping steel from the converter, lime is added at a rate of 2.5 kg / t of steel, without deoxidizing the slag and molten steel;

[0075] 3) LF Refining

[0076] The molten steel is heated to a temperature of 1605℃. Neither the top slag nor the molten steel is deoxidized. After the temperature is raised to 1605℃, the ladle is stirred by medium-intensity argon blowing at a flow rate of 600L / min for 8min. The temperature at the station is controlled at 1610℃.

[0077] 4) RH refining

[0078] The molten steel is subjected to oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled at 1.2 m³ / min. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure circulation treatment for 10 minutes after alloying; the top slag is not subjected to reduction modification.

[0079] In this embodiment, the molten steel obtained after RH refining has a Mn content of 0.017%, a S content of 0.002%, a P content of 0.003%, and a total oxygen content (TO) of 0.003%.

[0080] Example 3

[0081] In this embodiment, the molten iron before pretreatment contains 0.20% Mn, 0.09% P, 0.02% S, and 0.55% Si.

[0082] The smelting method for ultra-low manganese steel in this embodiment includes the following steps:

[0083] 1) Hot metal pretreatment

[0084] The hot metal pretreatment process includes pre-slag removal and post-slag removal, controlling the amount of residual slag in the hot metal ladle to 1.5 kg / t of hot metal before it enters the converter, and the sulfur content of the hot metal to 0.0006%.

[0085] 2) Converter smelting

[0086] a. Before blowing, add low-sulfur, low-alloy scrap steel according to heat balance;

[0087] b. The converter bottom blowing adopts a strong-medium-weak mode, with a bottom blowing intensity of 0.042 Nm in the early stage of blowing. 3 / min / t, mid-term bottom blowing intensity is 0.032Nm 3 / min / t, the later bottom blowing intensity is 0.026Nm. 3 / min / t;

[0088] c. During the 250s of converter blowing, double slag operation is carried out. 50s before the double slag operation, pellet ore is added at an addition rate of 15kg / t steel, and the slag pouring temperature is controlled at 1400℃. The slag basicity before double slag operation is 1.5, and the amount of double slag poured is 2 / 3 of the slag amount.

[0089] d. When the blowing time reaches 55%, lime and pellet ore are added, with a pellet ore addition amount of 10 kg / t steel; the final converter temperature is 1585℃, the final carbon content is 0.028%, and the final converter slag basicity is 2.7.

[0090] e. Double slag blocking is used when tapping steel from the converter to control the slag thickness at 40mm;

[0091] f. When tapping steel from the converter, lime is added at a rate of 1.5 kg / t of steel, without deoxidizing the slag and molten steel;

[0092] 3) LF Refining

[0093] The molten steel is heated to a temperature of 1605℃. Neither the top slag nor the molten steel is deoxidized. After the temperature is raised to 1605℃, the ladle is stirred by medium-intensity argon blowing at a flow rate of 500L / min for 7min. The temperature at the station is controlled at 1600℃.

[0094] 4) RH refining

[0095] The molten steel is subjected to oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled at 0.5 m³ / min. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure circulation treatment for 7 minutes after alloying; the top slag is not subjected to reduction modification.

[0096] In this embodiment, the molten steel obtained after RH refining has a Mn content of 0.016%, a S content of 0.0017%, a P content of 0.0045%, and a total oxygen content (TO) of 0.0028%.

[0097] Example 4

[0098] In this embodiment, the molten iron before pretreatment contained 0.18% Mn, 0.095% P, 0.022% S, and 0.2% Si.

[0099] The smelting method for ultra-low manganese steel in this embodiment includes the following steps:

[0100] 1) Hot metal pretreatment

[0101] The hot metal pretreatment process includes pre-slag removal and post-slag removal to control the amount of residual slag in the hot metal ladle to 1.6 kg / t of hot metal before it enters the converter, and the sulfur content of the hot metal to 0.0004%.

[0102] 2) Converter smelting

[0103] a. Before blowing, add low-sulfur, low-alloy scrap steel according to heat balance;

[0104] b. The converter bottom blowing adopts a strong-medium-weak mode, with a bottom blowing intensity of 0.044 Nm in the early stage of blowing. 3 / min / t, mid-term bottom blowing intensity is 0.035Nm 3 / min / t, the later bottom blowing intensity is 0.022Nm. 3 / min / t;

[0105] c. During the 250s of converter blowing, double slag operation is carried out. 35s before the double slag operation, pellet ore is added at an addition rate of 22kg / t steel, and the slag pouring temperature is controlled at 1360℃. The slag basicity before double slag operation is 1.4, and the amount of double slag poured is 1 / 2 of the slag amount.

[0106] d. When the blowing time reaches 60%, lime and pellet ore are added, with a pellet ore addition rate of 9 kg / t steel; the final converter temperature is 1595℃, the final carbon content is 0.025%, and the final converter slag basicity is 2.6.

[0107] e. Double slag blocking is used when tapping steel from the converter to control the slag thickness at 40mm;

[0108] f. When tapping steel from the converter, lime is added at a rate of 2.2 kg / t of steel, without deoxidizing the slag and molten steel;

[0109] 3) LF Refining

[0110] The molten steel is heated to a higher temperature. Neither the top slag nor the molten steel is deoxidized. After the temperature is raised to 1598℃, the ladle is stirred with medium intensity argon, with an argon flow rate of 450L / min and a stirring time of 7.5min. The temperature at the station is controlled at 1612℃.

[0111] 4) RH refining

[0112] The molten steel is subjected to oxygen blowing for decarburization and demanganese removal, with the oxygen blowing rate controlled at 0.8 m³ / min. 3 / t steel, after decarburization, undergoes deoxidation and alloying, followed by pure circulation treatment for 7.5 minutes after alloying; the top slag is not subjected to reduction modification.

[0113] In this embodiment, the molten steel obtained after RH refining has a Mn content of 0.014%, a S content of 0.0010%, a P content of 0.0035%, and a total oxygen content (TO) of 0.0025%.

[0114] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method of smelting an ultra-low manganese steel, characterized in that, It comprises the following steps: 1) hot metal pretreatment Mn content ≤0.30% before hot metal pretreatment; 2) converter smelting a. low-sulfur low-alloy scrap steel is added according to heat balance before blowing; b. The converter bottom blowing adopts strong-medium-weak mode, the bottom blowing intensity in the early stage is 0.035~0.040 Nm 3 / min / t, the bottom blowing intensity in the medium stage is 0.030~0.035 Nm 3 / min / t, the bottom blowing intensity in the late stage is 0.020~0.025 Nm 3 / min / t; c. double-slag operation is performed when the converter blowing time is 250~280 s, and the tapping slag temperature is 1350~1370 ℃; d. lime and pellet ore are added when the blowing time process is 50~60% to further slagging and temperature control, and the converter endpoint temperature is controlled at 1585~1620 ℃, and the endpoint C content is ≤0.03%; 3) LF refining The top slag and molten steel are not subjected to deoxidation treatment, the ladle is subjected to argon blowing stirring after the molten steel is heated to 1595~1605 ℃, the argon blowing flow is 400~600 L / min, and the stirring time is 5~10 min; 4) RH refining The molten steel is subjected to oxygen blowing decarburization and manganese removal, and deoxidation and alloying are performed after decarburization is completed; the Mn content in the molten steel after RH refining is ≤0.02%.

2. The smelting method of ultra-low manganese steel according to claim 1, characterized in that, The pellet ore is added 30~50 s before the double-slag operation.

3. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The slag basicity before the double-slag operation is 1.2~1.6, the double-slag tapping amount is 1 / 2~2 / 3 of the slag amount, and the converter final slag basicity is 2.5~3.

0.

4. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The converter tapping is subjected to double-slag blocking, and the slag thickness is controlled to be ≤40 mm; lime is added during the converter tapping, and the slag and molten steel are not subjected to deoxidation.

5. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The LF refining off-site temperature is controlled at 1600~1620 ℃.

6. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The RH refining oxygen blowing amount is 0.5~1.5 m 3 / t steel, after alloying, pure circulation treatment for 8~10 min.

7. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The front slagging and rear slagging are performed during the hot metal pretreatment process, the residual slag amount in the hot metal ladle before entering the converter is controlled to be ≤2 kg / t of hot metal, and the hot metal S content is ≤0.001%.

8. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The S content in the molten steel after the RH refining is completed is ≤0.002%, the P content is ≤0.005%, and the total oxygen content T.O is ≤0.003%.

9. The method of smelting ultra-low manganese steel according to claim 1, characterized in that, The P content before the hot metal pretreatment is ≤0.12%, the S content is ≤0.03%, and the Si content is 0.2~0.8%.