Smelting method for improving number of continuous casting furnaces by controlling content of Mg dissolved in molten steel

Abstract

The invention relates to the technical field of continuous casting production processes, in particular to a smelting method for controlling the content of Mg dissolved in molten steel and increasing the number of continuous casting furnaces. The production process flow is BOF-LF-RH-CCM, and 250-350 kg of lime is expected to be added into refining slag at the end moment of LF smelting; the RH vacuum furnace is used for carrying out degassing and inclusion removal treatment on the molten steel, and RH lifting gas is Ar + (0.15%-0.20%) O2; cCM continuous casting is conducted, a tundish coating material is made of aluminum oxide, and the content of MgO is smaller than or equal to 8%. According to the method, by controlling the solubility of the refining slag to MgO and combining the RH to increase the content of trace O2 in gas and the alumina tundish, the content of Mg dissolved in the molten steel is controlled to be extremely low, MgO.Al2O3 inclusions regenerated in the previous continuous casting process are inhibited, and therefore generation of the inclusions prone to nodulation is eradicated. According to the method, the number of molten steel continuous casting furnaces of aluminum deoxidized non-calcium treated steel can be increased from less than or equal to 5 to more than or equal to 15.

Description

Technical Field

[0001] The invention relates to the technical field of continuous casting production process, and in particular to a smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces. Background Art

[0002] The main process of continuous casting production is that molten steel flows from the ladle through the tundish, and then enters the crystallizer from the tundish to solidify into a steel shell. The solidified steel billet is clamped by the straightening machine for continuous casting, which greatly improves the production efficiency compared to die casting. At present, the proportion of steel produced by continuous casting is close to 100%. For silicon deoxidized steel or aluminum deoxidized calcium treated steel, the number of continuous casting furnaces can be stably controlled to ≥15 furnaces.

[0003] For high-clean steel, calcium treatment is prohibited due to high requirements for inclusions. Although the inclusions in the steel have been largely removed after LF+RH refining and only a small amount of low-melting calcium-aluminate inclusions remain, the Mg dissolved in the steel will generate a large amount of high-melting-point MgO·Al2O3 inclusions in the steel again due to weak secondary oxidation during the CCM continuous casting process. These inclusions will form nodules at the submerged nozzle, thereby deteriorating the castability of the steel, and ultimately resulting in the number of stable continuous casting furnaces of ≤5, which greatly reduces production efficiency. Summary of the invention

[0004] In view of the shortcomings of the existing methods, the present invention aims to solve the problem of small number of continuous casting furnaces for aluminum deoxidized non-calcium treated steel, and ultimately achieve the requirement of ≥15 continuous casting furnaces.

[0005] The technical solution adopted by the present invention is: a smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces, including the following requirements: (1) BOF converter smelting: The end point temperature of BOF converter smelting is ≥1580℃, the end point C is ≥0.05%, and the end point P is ≤0.035%. Aluminum blocks, alloys and slag are added after steel is tapped.

[0006] (2) LF furnace refining: conventional smelting is carried out after arrival at the station. At the end of LF smelting, lime is added to the slag surface. The LF steel-making temperature is ≥1580℃, and alloying is completed. At the end of LF, the amount of lime added to the refined slag is 250~350kg.

[0007] (3) RH furnace vacuum treatment: conventional smelting, the lifting gas type is Ar+O2 mixed gas; RH vacuum treatment time ≥15min; calcium treatment amount 0; soft blowing time ≥5min; RH lifting gas requires O2 content of 0.15%~0.20%.

[0008] (4) CCM continuous casting machine is responsible for casting molten steel. The tundish coating material is required to be alumina. The Al2O3 content in the tundish coating material is ≥88%, the MgO content is ≤8%, and the rest is mainly SiO2 and unavoidable impurities.

[0009] The reason for adding lime to the refined slag at the end of LF is that during the LF smelting process, the refined slag will continuously corrode the MgO ladle slag line bricks due to its own characteristics, dissolving the MgO in the slag line bricks as the main refractory material into the refined slag, usually causing the MgO content in the refined slag to increase from 2% to 8%; and the MgO in the refined slag will continue to transfer Mg to the molten steel, and its reaction formula (1) is: (MgO) 炉渣 →[Mg] 钢液 +[O] 钢液 , which eventually leads to a continuous increase in the Mg content in the molten steel; the type of inclusions in the steel gradually changes from Al2O3 when aluminum blocks are added for deoxidation to MgO·Al2O3; the transformation reaction equations (2) to (4) are: 2[Al] 钢液 +3[O] 钢液 →(Al2O3) 夹杂物 ; [Mg] 钢液 +[O] 钢液 →(MgO) 夹杂物 ; (MgO) 夹杂物 +(Al2O3) 夹杂物 →(MgO·Al2O3) 夹杂物 . In summary, controlling MgO·Al2O3 inclusions requires controlling the Mg content of the molten steel, and the key to controlling the Mg content of the molten steel lies in controlling the MgO content of the slag. Secondly, the LF smelting process needs to ensure that the refined slag has good fluidity so that it can quickly absorb inclusions and facilitate the submerged arc heating of the refining electrode. In order to ensure efficient production in the LF smelting process, the CaO in the refined slag is controlled to be close to but not saturated. At this time, the refined slag has the best effect in absorbing inclusions, and the melting point of the refined slag and the solubility of MgO are within an acceptable range. If the CaO content further increases to exceed the solubility and reaches a saturated state, the melting point of the refined slag will increase, the fluidity of the slag will deteriorate, but the solubility of MgO will be greatly reduced. Therefore, in order to ensure the refining effect of the LF smelting process and take into account that the MgO content in the subsequent refined slag will not continue to increase, lime needs to be added to the refined slag at the end of LF. If the amount of lime added is less than 250kg, it is not possible to effectively inhibit the erosion of slag on MgO slag bricks, and thus it is not possible to prevent the increase of MgO content in refined slag; if the amount of lime added is greater than 350kg, the melting point of slag is too high, the fluidity deteriorates, and it is not possible to effectively remove inclusions and cover the molten steel. Therefore, in order to take into account the solubility of slag to MgO, the melting point of slag, the fluidity and the absorption effect of inclusions, the optimal amount of lime added is 250~350kg.

[0010] The reason why the RH lifting gas requires an O2 content of 0.15%~0.20% is that the RH furnace usually uses a single type of Ar as the lifting gas. The RH cycle process can efficiently remove the MgO·Al2O3 inclusions that already exist in the molten steel. Usually, the removal rate is close to 100%, leaving a small amount of calcium aluminate inclusions. However, when the molten steel is hoisted to the continuous casting platform for casting, a large amount of MgO·Al2O3 inclusions will be regenerated in the continuous casting tundish due to weak secondary oxidation (increase in O content ≤1ppm). Reaction equation (5) is: [Mg] 钢液溶解Mg +[O] 二次氧化的O +[Al] 钢液溶解Al →(MgO·Al2O3) 夹杂物 . The regenerated MgO·Al2O3 inclusions cannot be effectively removed during the continuous casting process, and will form nodules on the rod head of the continuous casting flow control plug rod, the bowl mouth of the immersion nozzle and the inner wall of the immersion nozzle, hindering the flow of molten steel. At the same time, they occasionally fall into the molten steel and affect the cleanliness of the molten steel. Therefore, the RH process is used to increase the Ar in the gas and mix a trace amount of O2 to react with the Mg and Al dissolved in the molten steel in advance to generate MgO·Al2O3 inclusions, which are efficiently removed by the RH process. In the subsequent continuous casting process, since the Mg dissolved in the molten steel is already in an extremely low state, the secondary oxidation conditions at this time can no longer meet the [Mg], [O], [Al] concentration product, and thus reaction equation (5) will not occur, and ultimately MgO·Al2O3 inclusions cannot be generated due to secondary oxidation. When the O2 content is less than 0.15%, it is not possible to effectively control the dissolved Mg content in the molten steel to an extremely low content; when the O2 content is greater than 0.20%, the O concentration in the molten steel is too high, and the loss of elements such as Al, C, Si, Mn, and Cr in the steel is too large, and the adjustment is too complicated and uneconomical. Therefore, the most suitable O2 content is 0.15%~0.20%.

[0011] The reason for the requirement of Al2O3 content ≥88% and MgO content ≤8% in the tundish coating is that after smelting in the LF and RH processes, the dissolved Mg content in the molten steel is extremely low. At this time, it is necessary to strictly control the Mg content in the refractory and auxiliary materials in contact with the molten steel. The tundish refractory and covering agent have larger contact areas with the molten steel in the tundish. The conventional tundish covering agent uses a low-melting-point calcium aluminate covering agent with a MgO content of ≤2%, and the possibility of transferring Mg to the molten steel is extremely low. The composition of the conventional tundish coating is MgO≥85%, and the probability of transferring Mg to the molten steel is extremely high. Therefore, in order to further control the Mg content of the molten steel and prevent the refractory from transferring Mg to the molten steel, thereby causing the generation of MgO·Al2O3, the MgO content of the tundish coating needs to be strictly controlled. Considering various indicators such as the service life of the refractory and the control requirements for the transfer of Mg by the molten steel, the optimal ratio is Al2O3 content ≥88%, MgO content ≤8%, and the rest is SiO2 and unavoidable impurities. When the MgO content is greater than 8%, the Mg content in the molten steel increases, and MgO·Al2O3 inclusions begin to appear in the steel in large quantities.

[0012] The beneficial effects of the present invention are as follows: by controlling the solubility of MgO in the refined slag, combining RH to increase the trace O2 content in the gas and the alumina tundish, the Mg content dissolved in the molten steel is controlled to be extremely low, and the MgO·Al2O3 inclusions regenerated in the previous continuous casting process are suppressed, thereby eliminating the generation of nodule-prone inclusions. The present invention can increase the number of continuous casting furnaces for aluminum-deoxidized non-calcium treated steel from ≤5 furnaces to ≥15 furnaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 For Example 1 (a) continuous casting liquid level fluctuation curve 21 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 2 For Example 2 (a) continuous casting liquid level fluctuation curve 17 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 3 For Example 3 (a) continuous casting liquid level fluctuation curve 16 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 4 For Example 4 (a) continuous casting liquid level fluctuation curve 17 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 5 For Example 5 (a) continuous casting liquid level fluctuation curve 15 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 6For comparative example 1 (a) continuous casting liquid level fluctuation curve 7 furnaces; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 7 For comparative example 2 (a) continuous casting liquid level fluctuation curve 8 furnaces; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Figure 8 For comparative example 3 (a) continuous casting liquid level fluctuation curve 6 furnaces; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Fig. 9 For comparative example 4 (a) continuous casting liquid level fluctuation curve 10 furnace; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Fig.10 For comparative example 5 (a) continuous casting liquid level fluctuation curve 8 furnaces; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution; Fig.11 For comparative example 6 (a) continuous casting liquid level fluctuation curve of furnace 5; (b) RH end sample inclusion composition distribution; (c) CCM tundish sample inclusion composition distribution. DETAILED DESCRIPTION

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0015] Taking SUJ2 for automobile bearings as an example, the production of aluminum deoxidized non-calcium treated steel is organized. The standard composition requirements of the steel grade are shown in Table 1 below.

[0016] Table 1 Standard composition of SUJ2 steel, % C Si Mn P S Al Cr Ti 0.98~1.05 0.15~0.35 0.25~0.50 ≤0.025 ≤0.008 ≤0.05 1.4~1.6 ≤0.003 The main production processes of each process are as follows: BOF: Add about 40t scrap steel, about 120t molten iron, oxygen supply time about 9min, oxygen pressure 0.9MPa, oxygen consumption about 7000m 3 , add about 4600kg of lime, about 2200kg of light-burned dolomite, about 500kg of ore, the final point of steelmaking C is about 0.077%, P is about 0.014%, S is about 0.018%, the tapping temperature is about 1596℃, about 200kg of ferrosilicon, about 260kg of high carbon ferromanganese, about 2450kg of low carbon ferrochrome, about 1350kg of aluminum block, about 900kg of recarburizer, about 300kg of refined slag and about 600kg of lime.

[0017] LF: The temperature of the ladle is about 1470℃, the power supply time is about 40min, the smelting time is about 85min, and during the smelting process, about 100kg of cryolite, about 200kg of lime, about 20kg of aluminum particles, about 230kg of silicon carbide, about 500kg of low-titanium high-carbon ferrochrome, about 180kg of high-carbon ferromanganese, about 280kg of carburizer, about 20kg of aluminum wire, etc. are added for deoxidation and alloying, and the LF hanging ladle temperature is about 1560℃. The composition of the molten steel is roughly controlled as follows: C: 0.979%, Si: 0.176%, Mn: 0.294%, P: 0.014%, S: 0.008%, Al: 0.025%, Cr: 1.420%, Ti: 0.0019%.

[0018] At the end of LF, the operations are divided into: ① Add 300kg of lime to the refined slag; ② Add 250kg of lime to the refined slag; ③ Add 350kg of lime to the refined slag; ④ No lime is added; ⑤ Add 600 kg of lime to the refined slag.

[0019] RH: inlet temperature is about 1558℃, RH end temperature is about 1522℃, degassing time is about 25min, pressure holding time is about 20min, ultimate vacuum degree ≤67Pa, gas flow rate is 100Nm 3 / h, no calcium wire is fed after breaking the air. The soft blowing time is about 25min, and the bag temperature is about 1508℃. The composition of the molten steel is roughly controlled as follows: C: 0.987%, Si: 0.192%, Mn: 0.294%, P: 0.015%, S: 0.006%, Al: 0.0154%, Cr: 1.472%, Ti: 0.0020%.

[0020] RH boosting gas types are divided into: ①Ar+0.18%O2; ②Ar+0.15%O2; ③Ar+0.20%O2; ④Pure Ar; ⑤Ar+1%O2.

[0021] CCM: conventional continuous casting superheat is about 25℃, mold water flow is about 2000L / min, specific water volume is 0.25L / kg, mold electromagnetic stirring current is 300A, end electromagnetic stirring current is 300A, casting speed is 0.78m / min, integral internal water inlet and stopper rod are used for flow control. The composition of molten steel is roughly controlled as follows: C: 0.998%, Si: 0.190%, Mn: 0.294%, P: 0.015%, S: 0.006%, Al: 0.0132%, Cr: 1.484%, Ti: 0.0020%.

[0022] The materials of tundish coating are divided into: ①Al2O3 content is 92%, MgO content is 5%, and the rest is SiO2 and inevitable impurities; ②Al2O3 content is 88%, MgO content is 8%, and the rest is SiO2 and inevitable impurities; ③MgO content 95%, the rest is SiO2 and inevitable impurities Statistics: (1) Count the number of times x (unit: times / furnace) that the liquid level fluctuation in each furnace exceeds ±3 mm. When the value of x is ≥ 5, it is defined as being unable to continue continuous pouring, and the corresponding continuous pouring furnace number is the maximum continuous pouring furnace number.

[0023] (2) Statistics on the distribution of inclusions in the second continuous casting furnace in the examples and comparative examples were collected to analyze the inclusion control of the corresponding processes. The sampling process was RH end sample and CCM tundish sample. The ASPEX scanning electron microscope was used to analyze the sample with an area of ​​20 mm 2 . Example 1

[0024] The operation at the end of LF is: adding 300kg of lime to the refined slag; the RH lifting gas type is: Ar+0.18%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0025] The fluctuation of liquid level in each furnace is shown in Figure 1 (a) The number of continuous casting furnaces is 21.

[0026] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 1 As shown in (b) and (c).

[0027] Composition of RH broken air sample: C: 0.988%, Si: 0.202%, Mn: 0.293%, P: 0.015%, S: 0.006%, Al: 0.0155%, Cr: 1.477%, Ti: 0.0021%. Example 2

[0028] The operation at the end of LF is: add 250kg of lime to the refined slag; the RH lifting gas type is: Ar+0.18%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0029] The fluctuation of liquid level in each furnace is shown in Figure 2 (a) The number of continuous casting furnaces is 17.

[0030] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 2 As shown in (b) and (c).

[0031] Composition of RH broken air sample: C: 0.981%, Si: 0.201%, Mn: 0.294%, P: 0.015%, S: 0.005%, Al: 0.0154%, Cr: 1.478%, Ti: 0.0020%. Example 3

[0032] The operation at the end of LF is: add 300kg of lime to the refined slag; the RH lifting gas type is: Ar+0.15%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0033] The fluctuation of liquid level in each furnace is shown in Figure 3 (a) The number of continuous casting furnaces is 16.

[0034] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 3 As shown in (b) and (c).

[0035] Composition of RH broken air sample: C: 0.982%, Si: 0.199%, Mn: 0.298%, P: 0.015%, S: 0.006%, Al: 0.0159%, Cr: 1.471%, Ti: 0.0020%. Example 4

[0036] The operation at the end of LF is: add 250kg of lime to the refined slag; the RH lifting gas type is: Ar+0.18%O2; the material of the tundish coating is: Al2O3 content 88%, MgO content 8%, and the rest is SiO2 and unavoidable impurities.

[0037] The fluctuation of liquid level in each furnace is shown in Figure 4 (a) The number of continuous casting furnaces is 17.

[0038] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 4 As shown in (b) and (c).

[0039] Composition of RH broken air sample: C: 0.981%, Si: 0.211%, Mn: 0.299%, P: 0.015%, S: 0.005%, Al: 0.0151%, Cr: 1.472%, Ti: 0.0021%. Example 5

[0040] The operation at the end of LF is: add 250kg of lime to the refined slag; the RH lifting gas type is: Ar+0.15%O2; the material of the tundish coating is: Al2O3 content 88%, MgO content 8%, and the rest is SiO2 and unavoidable impurities.

[0041] The fluctuation of liquid level in each furnace is shown in Figure 5 (a) The number of continuous casting furnaces is 15.

[0042] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 5 As shown in (b) and (c).

[0043] Composition of RH broken air sample: C: 0.992%, Si: 0.210%, Mn: 0.290%, P: 0.015%, S: 0.004%, Al: 0.0161%, Cr: 1.480%, Ti: 0.0022%. Comparative Example 1

[0044] The operation at the end of LF is: no lime is added to the refined slag; the RH lifting gas type is: Ar+0.18%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0045] The fluctuation of liquid level in each furnace is shown in Figure 6 (a), the number of continuous casting furnaces is 7.

[0046] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 6 As shown in (b) and (c).

[0047] Composition of RH broken air sample: C: 0.980%, Si: 0.198%, Mn: 0.292%, P: 0.015%, S: 0.006%, Al: 0.0155%, Cr: 1.471%, Ti: 0.0020%. Comparative Example 2

[0048] The operation at the end of LF is: adding 600kg of lime to the refined slag; the RH lifting gas type is: Ar+0.18%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0049] The fluctuation of liquid level in each furnace is shown in Figure 7 (a), the number of continuous casting furnaces is 8.

[0050] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 7 As shown in (b) and (c).

[0051] Composition of RH broken air sample: C: 0.982%, Si: 0.208%, Mn: 0.298%, P: 0.012%, S: 0.006%, Al: 0.0158%, Cr: 1.472%, Ti: 0.0019%. Comparative Example 3

[0052] The operation at the end of LF is: adding 300kg of lime to the refined slag; the RH lifting gas type is: pure Ar; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0053] The fluctuation of liquid level in each furnace is shown in Figure 8 (a) The number of continuous casting furnaces is 6.

[0054] Sampling RH end sample, CCM tundish sample, inclusion distribution see Figure 8 As shown in (b) and (c).

[0055] Composition of RH broken air sample: C: 0.989%, Si: 0.211%, Mn: 0.290%, P: 0.015%, S: 0.007%, Al: 0.0157%, Cr: 1.474%, Ti: 0.0021%. Comparative Example 4

[0056] The operation at the end of LF is: adding 300kg of lime to the refined slag; the RH lifting gas type is: Ar+1%O2; the material of the tundish coating is: Al2O3 content 92%, MgO content 5%, and the rest is SiO2 and unavoidable impurities.

[0057] The fluctuation of liquid level in each furnace is shown in Fig. 9 (a) The number of continuous casting furnaces is 10.

[0058] Sampling RH end sample, CCM tundish sample, inclusion distribution see Fig. 9 As shown in (b) and (c).

[0059] Composition of RH broken air sample: C: 0.627%, Si: 0.013%, Mn: 0.131%, P: 0.015%, S: 0.006%, Al: 0.0062%, Cr: 1.050%, Ti: 0.0013%.

[0060] Since the alloy elements C, Si, Mn, Al and Cr are highly oxidized, the alloy needs to be re-fed after RH breaks through the air, which affects the production rhythm and increases the production cost. Comparative Example 5

[0061] The operation at the end of LF is: adding 300kg of lime to the refined slag; the RH raising gas type is: Ar+0.18%O2; the material of the tundish coating is: MgO content 95%, the rest is SiO2 and unavoidable impurities.

[0062] The fluctuation of liquid level in each furnace is shown in Fig.10 (a), the number of continuous casting furnaces is 8.

[0063] Sampling RH end sample, CCM tundish sample, inclusion distribution see Fig.10 As shown in (b) and (c).

[0064] Composition of RH broken air sample: C: 0.980%, Si: 0.221%, Mn: 0.274%, P: 0.015%, S: 0.006%, Al: 0.0150%, Cr: 1.478%, Ti: 0.0020%. Comparative Example 6

[0065] The operation at the end of LF is: no lime is added to the refined slag; the RH lifting gas type is: pure Ar; the material of the tundish coating is: MgO content 95%, the rest is SiO2 and unavoidable impurities.

[0066] The fluctuation of liquid level in each furnace is shown in Fig.11 (a) The number of continuous casting furnaces is 5.

[0067] Sampling RH end sample, CCM tundish sample, inclusion distribution see Fig.11 As shown in (b) and (c).

[0068] Composition of RH broken air sample: C: 0.989%, Si: 0.228%, Mn: 0.279%, P: 0.015%, S: 0.005%, Al: 0.0159%, Cr: 1.479%, Ti: 0.0019%.

[0069] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces, characterized in that: The production process is: BOF converter smelting - LF refining - RH vacuum treatment - CCM continuous casting, including the following requirements: (1) LF refining, adding lime to the refining slag at the end of smelting; (2) RH vacuum treatment, the lifting gas type is Ar+O2 mixed gas; (3) CCM continuous casting requires the tundish coating to be alumina.

2. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: The end point temperature of BOF converter smelting is ≥1580℃, end point C is ≥0.05%, and end point P is ≤0.035%; aluminum blocks, alloys and slag are added after steelmaking.

3. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: LF refining steel tapping temperature ≥1580℃, completing alloying.

4. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: At the end of LF refining, the amount of lime added to the refining slag is 250~350kg.

5. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: The RH raising gas requires an O2 content of 0.15%~0.20%.

6. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: RH vacuum treatment time ≥15min; calcium treatment amount 0; soft blowing time ≥5min.

7. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: The Al2O3 content in the tundish coating is ≥88%, the MgO content is ≤8%, and the rest is SiO2 and unavoidable impurities.

8. The smelting method for controlling the dissolved Mg content of molten steel and increasing the number of continuous casting furnaces according to claim 1, characterized in that: The number of continuous molten steel pouring furnaces is ≥15.

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