Smelting process of high-manganese wear-resistant steel

Abstract

The invention belongs to the technical field of steel and iron smelting, and discloses a smelting process of high-manganese wear-resistant steel, after blast furnace molten iron is pretreated by a dephosphorization converter, the P content of the molten iron is smaller than or equal to 0.007%, the C content of the molten iron is larger than or equal to 2.8%, then mother liquor is added into an AOD converter for smelting, and the smelting process comprises a Si / Al removal stage, a main decarbonization stage, a dynamic decarbonization stage, a manganese alloying stage, a reduction stage and a tapping stage. By utilizing the dynamic conditions of efficient decarburization of AOD top side combined blowing and side blowing strong stirring, the manganese yield reaches 98% or above, the effect of decarburization and manganese protection is achieved, and the molten steel inclusion control level is far higher than that of a BOF converter. Compared with a KR desulfurization, BOF converter, LF (temperature rise), VD (vacuum decarburization) and LF process, the high-manganese wear-resistant steel is smelted by adopting a dephosphorization converter (DP), AOD converter and LF process, so that the smelting process is short, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and specifically relates to a smelting process for high manganese wear-resistant steel. Background Technology

[0002] High-manganese wear-resistant steel possesses work-hardening characteristics unmatched by other wear-resistant materials. Under large impact loads or contact stresses, the surface layer of the steel plate rapidly hardens and martensite forms, with the surface hardness increasing rapidly from HB200 to over HB500, resulting in a highly wear-resistant surface layer. Meanwhile, the inner austenite layer retains good impact toughness. It is widely used in machinery and equipment in industries such as mining, coal, cement, metallurgy, building materials, railways, and power, including shot blasting machines, ball mills, crushers, and scraper loosening machines. Due to its high manganese content and low phosphorus and sulfur content, high-manganese wear-resistant steel is difficult to smelt. Henan Iron and Steel Group uses a "150-ton converter + double refining (LF / VD)" process to smelt high-manganese wear-resistant steel, but this process is lengthy and costly. AOD converters use argon-oxygen mixed gas blowing, which can efficiently desulfurize and improve manganese alloying and steel purity control; however, AOD converters are rarely used for smelting high-manganese wear-resistant steel, failing to fully utilize their equipment advantages. Therefore, it is necessary to optimize the smelting process of high-manganese wear-resistant steel in order to achieve efficient production and reduce costs. Summary of the Invention

[0003] This invention provides a smelting process for high-manganese wear-resistant steel, which utilizes the efficient decarburization of AOD top-side combined blowing and the strong stirring kinetics of side blowing to achieve efficient decarburization, desulfurization and improve manganese recovery.

[0004] Therefore, the present invention adopts the following technical solution: A smelting process for high-manganese wear-resistant steel involves first pretreating blast furnace hot metal in a dephosphorization converter, and then utilizing the efficient decarburization of AOD top-side combined blowing and the strong stirring kinetics of side blowing to achieve efficient decarburization, desulfurization, and manganese alloying. The process includes the following steps: Step 1: Pre-treat blast furnace hot metal in a dephosphorization converter: The furnace charge includes iron oxide scale, lime, and dolomite; During the oxygen blowing and slag forming stage, lime is added according to the silicon content of the blast furnace molten iron to carry out oxygen blowing and slag forming; During the dephosphorization stage, the phosphorus content is controlled below 0.007%, and the carbon content is between 2.8% and 3.5%. The steel is tapped, and the tapping temperature is controlled at 1420-1450℃. Step 2: Smelting high-manganese wear-resistant steel in an AOD converter: Main decarburization period: An argon-oxygen mixture with a ratio of O2:Ar=7:1 is blown into the furnace for 15-20 minutes. 28-32 kg / t of lime and 250-350 kg of heated aluminum are added. The furnace is then spun with a top lance until carbon is reduced to 1.0-1.5%. Dynamic decarburization period 1: Top lance blowing is cancelled, and an argon-oxygen mixture with an O2:Ar ratio of 3:1 is blown into the furnace for 5-10 minutes, reducing C to 0.8-1.0%; Dynamic decarburization period 2: Add 850-950Kg of aluminum granules, blow into the furnace an argon-oxygen mixture with a ratio of O2:Ar=3:1, and 15-20Kg / t of lime, and blow for 6-8 minutes; Manganese alloying: Add 110-120 kg / t of electrolytic manganese; Reduction period: Add 250-350Kg aluminum granules and 500-600Kg fluorite, reduce for 3-5 minutes, pour off 40-50% of the slag after reduction, measure the temperature and take samples, and adjust the composition according to the test results; Steel tapping: Add 200-400 kg of lime, stir evenly, and then tap the steel.

[0005] The beneficial effects of this invention are as follows: 1. Before the molten iron is added to the AOD converter, the phosphorus content has been reduced to below 0.007%. The AOD smelting process includes oxidation, manganese alloying, reduction, and desulfurization stages. Aluminum granules are used for heating and reduction, and the C, Mn, and S in the molten steel are effectively controlled. 2. The AOD oxidation stage does not involve the oxidation of manganese; instead, manganese alloying occurs simultaneously with reduction, resulting in a Mn recovery rate of over 98%. 3. Compared with the KR desulfurization + BOF converter + LF (heating) + VD (vacuum decarburization) + LF process, the dephosphorization converter (DP) + AOD converter + LF process is used to smelt high manganese wear-resistant steel. The slag produced by the AOD converter is a reducing aluminum slag, and the steel output T[O] ≤ 30ppm. The steel has high purity and does not require the LF (heating) + VD process. The smelting process is shorter and more economical. Detailed Implementation

[0006] The present invention will be further described below with reference to specific embodiments: Example 1 Step 1: Pre-treat blast furnace hot metal in a dephosphorization converter The furnace charge includes iron oxide scale, lime, dolomite, etc. During the oxygen blowing and slagging stage, the blast furnace hot metal composition was 4.81% C, 0.70% Si, 0.68% Mn, and 0.08% P. The process included adding 0.8t of lime powder, 2.7t of iron oxide scale, 1.6t of lightly calcined dolomite, 3.3t of active lime, 1.6t of quicklime, and 0.3t of fluorite. Oxygen blowing was 2364 Nm³. 3 Nitrogen 324 Nm 3 The basicity of binary slag should be controlled at 2.3; During the dephosphorization stage, the sample tested showed a phosphorus content of 0.006% and a carbon content of 2.82%. The steel was tapped at a temperature of 1445℃.

[0007] Step 2: Smelting high-manganese wear-resistant steel in an AOD converter. Main decarburization period: An argon-oxygen mixture with a ratio of O2:Ar=7:1 is blown into the furnace for 18 minutes. 30 kg / t of lime and 300 kg of heated aluminum are added. The furnace is then smelted with a top lance until carbon is reduced to 1.32%. Dynamic decarburization period 1: Top lance blowing is cancelled, and an argon-oxygen mixture with a ratio of O2:Ar=3:1 is blown into the furnace for 6 minutes, reducing C to 0.84%; Dynamic decarburization period 2: Add 900 kg of aluminum granules, blow into the furnace an argon-oxygen mixture with a ratio of O2:Ar=3:1, add 20 kg / t of lime, and blow for 6 minutes; Manganese alloying: Add 110-120 kg / t of electrolytic manganese.

[0008] Reduction period: Add 300Kg aluminum granules and 520Kg fluorite, reduce for 3 minutes, pour off 40% of the residue after reduction, measure the temperature and take samples, and adjust the composition according to the test results.

[0009] Tapping: Add 200 kg of lime, stir evenly, and then tap the steel. The composition of the tapped steel is shown in Table 1. Table 1 steel grades C% Si% Mn% P% S% Mn13 0.86 0.12 12.12 0.003 0.002 Example 2 Step 1: Pre-treat blast furnace hot metal in a dephosphorization converter The furnace charge includes iron oxide scale, lime, dolomite, etc. During the oxygen blowing and slagging stage, the blast furnace hot metal composition was 4.27% C, 0.46% Si, 0.78% Mn, and 0.10% P. The process included the addition of 0.8t lime powder, 3.9t iron oxide scale, 1.4t lightly calcined dolomite, 0.6t active lime, 1.3t quicklime, and 0.2t fluorite. Oxygen blowing was at 1858 Nm³. 3 Nitrogen 308 Nm 3 The basicity of binary slag is controlled at 2.5; During the dephosphorization stage, the sample tested showed a phosphorus content of 0.007% and a carbon content of 2.87%. The steel was tapped at a temperature of 1450℃. Step 2: Smelting high-manganese wear-resistant steel in an AOD converter. Main decarburization period: An argon-oxygen mixture with a ratio of O2:Ar=7:1 is blown into the furnace for 18 minutes. 31 kg / t of lime and 320 kg of heated aluminum are added. The furnace is then smelted with a top lance until carbon is reduced to 1.2%. Dynamic decarburization period 1: Top lance blowing is cancelled, and an argon-oxygen mixture with a ratio of O2:Ar=3:1 is blown into the furnace for 5 minutes, and C is reduced to 0.87%; Dynamic decarburization period 2: Add 920 kg of aluminum granules, blow an argon-oxygen mixture with a ratio of O2:Ar=3:1 into the furnace, add 20 kg / t of lime, and blow for 6 minutes; Manganese alloying: 120 kg / t of electrolytic manganese is added.

[0010] Reduction period: Add 305Kg aluminum granules and 550Kg fluorite, reduce for 4 minutes, pour off 50% of the residue after reduction, measure the temperature and take samples, and adjust the composition according to the test results.

[0011] Tapping: Add 300 kg of lime, stir evenly, and then tap the steel. The composition of the tapped steel is shown in Table 2. Table 2 steel grades C% Si% Mn% P% S% Mn13 0.87 0.14 12.10 0.010 0.001 Example 3 Step 1: Pre-treat blast furnace hot metal in a dephosphorization converter The furnace charge includes iron oxide scale, lime, dolomite, etc. During the oxygen blowing and slagging stage, the blast furnace hot metal composition was 4.28% C, 0.38% Si, 0.78% Mn, and 0.10% P. The process included adding 3.9t of lime oxide scale, 1.5t of lightly calcined dolomite, 0.8t of lime powder, 1.6t of quicklime, and 0.16t of fluorite, and blowing oxygen at 1806 Nm³. 3 Nitrogen 293 Nm 3 The basicity of binary slag should be controlled at 2.3; During the dephosphorization stage, the sample tested showed a phosphorus content of 0.007% and a carbon content of 2.92%. The steel was tapped at a temperature of 1420℃. Step 2: Smelting high-manganese wear-resistant steel in an AOD converter. Main decarburization period: An argon-oxygen mixture with a ratio of O2:Ar=7:1 is blown into the furnace for 18 minutes. 32 kg / t of lime and 300 kg of heated aluminum are added. The furnace is then smelted with a top lance until carbon is reduced to 1.2%. Dynamic decarburization period 1: Top lance blowing is cancelled, and an argon-oxygen mixture with a ratio of O2:Ar=3:1 is blown into the furnace for 7 minutes, reducing C to 0.86%; Dynamic decarburization period 2: Add 950 kg of aluminum granules, blow into the furnace an argon-oxygen mixture with a ratio of O2:Ar=3:1, add 20 kg / t of lime, and blow for 6 minutes; Manganese alloying: 120 kg / t of electrolytic manganese is added.

[0012] Reduction period: Add 310Kg aluminum granules and 500Kg fluorite, reduce for 3 minutes, pour off 40% of the residue after reduction, measure the temperature and take samples, and adjust the composition according to the test results.

[0013] Tapping: Add 200 kg of lime, stir evenly, and then tap the steel. The composition of the tapped steel is shown in Table 3. Table 3 steel grades C% Si% Mn% P% S% Mn13 0.84 0.11 12.14 0.011 0.003 The innovative aspects of this process method are: In BOF converter smelting, manganese is easily oxidized in large quantities during decarburization, resulting in low manganese recovery. Furthermore, severe oxidation of the molten steel during smelting necessitates VD treatment to improve steel purity, leading to a lengthy and costly smelting process. AOD converter, employing an argon-oxygen mixed gas blowing process, avoids the extensive oxidation of manganese during decarburization, achieving a manganese recovery rate of over 98%, thus achieving the effect of "decarburization while preserving manganese." This significantly reduces smelting costs. Moreover, in the later stages of AOD converter smelting, the slag components are fully reduced, eliminating the need for LF refining and resulting in a much higher level of inclusion control in the molten steel compared to BOF converters. AOD converters are suitable for producing high-performance, high-purity, high-manganese wear-resistant steel. The slag composition of AOD converters is shown in Table 4.

[0014] Table 4 TFe (%) CaO (%) SiO2 (%) MgO (%) Al2O3 (%) Cr2O3 (%) Binary alkalinity (R) 0.76 57.57 4.74 5.77 22.76 0.04 12.15

Claims

1. A process for smelting a high manganese abrasion resistant steel, characterized in that, Firstly, the molten iron from blast furnace is pretreated in a dephosphorization converter, and then high efficient decarburization, desulfurization and manganese alloying are carried out by using the high efficient decarburization of AOD top side combined blowing and the dynamic conditions of side blowing strong stirring, including the following process steps: Step 1: the molten iron from blast furnace is pretreated in a dephosphorization converter: The furnace charge comprises iron oxide scale, lime and dolomite; In the oxygen blowing slagging stage, lime is added according to the silicon content of the molten iron from blast furnace, and oxygen blowing slagging is carried out; In the dephosphorization stage, the P content is controlled to be below 0.007%, and the C content is 2.8-3.5%; Tapping, the tapping temperature is controlled to be 1420-1450℃; Step 2: smelting of high manganese wear-resistant steel is carried out in the AOD converter: Main decarburization stage: argon-oxygen mixed gas is blown into the furnace, the blowing time is 15-20 minutes, 28-32 Kg / t of lime is added, 250-350 Kg of aluminum is added, top gun blowing is carried out, and C is removed to 1.0-1.5%; Dynamic decarburization stage 1: the top gun blowing is cancelled, argon-oxygen mixed gas is blown into the furnace, the blowing time is 5-10 minutes, and C is removed to 0.8-1.0%; Dynamic decarburization stage 2: 850-950 Kg of aluminum particles are added, argon-oxygen mixed gas is blown into the furnace, 15-20 Kg / t of lime is added, and the blowing time is 6-8 minutes; Manganese alloying: 110-120 Kg / t of electrolytic manganese is added; Reduction stage: 250-350 Kg of aluminum particles and 500-600 Kg of fluorite are added, the reduction time is 3-5 minutes, after the reduction is finished, 40-50% of slag is poured, temperature sampling is carried out, and the composition is adjusted according to the test results; Tapping: 200-400 Kg of lime is added, and after uniform stirring, the molten iron is tapped.

2. A process for smelting high manganese abrasion resistant steel as claimed in claim 1 wherein, In the step 2, the proportion of argon-oxygen mixed gas blown in the main decarburization stage is O2: Ar = 7:

1.

3. A process for smelting high manganese abrasion resistant steel as claimed in claim 1 wherein, In the step 2, the proportion of argon-oxygen mixed gas blown in the dynamic decarburization stage 1 and the dynamic decarburization stage 2 is O2: Ar = 3: 1.