A high-phosphorus molten iron extremely low-sulfur, low-phosphorus hydrogen-doped pipeline steel steelmaking process control method

Abstract

The application discloses a high-phosphorus molten iron extremely-low-sulfur and low-phosphorus hydrogen-doped pipeline steel steelmaking process control method, which reduces the burden of LF desulfurization through post-furnace slag system treatment, effectively improves the refining rate, improves the production efficiency and guarantees continuous casting through over-treatment or re-treatment of LF refining; compared with conventional production, the desulfurization efficiency is improved through converter slag system and LF refining slagging process, the cleanliness of the steel is also greatly improved, and the final total oxygen content can be stably controlled within 0.0015%. The application aims to provide a steelmaking process control method for realizing low-phosphorus and extremely-low-sulfur chemical composition in the process of smelting hydrogen-doped pipeline steel from high-phosphorus molten iron, especially for smelting low-phosphorus steel and extremely-low-sulfur steel from high-phosphorus molten iron, the cleanliness of the steel is also greatly improved, and the final total oxygen content can be stably controlled within 0.0015%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smelting low-phosphorus steel and extremely low-sulfur from high-phosphorus molten iron, and particularly relates to a high-phosphorus molten iron extremely low-sulfur and low-phosphorus hydrogen-doped pipeline steel smelting process control method. BACKGROUND

[0002] According to the subdivided market demand, developing high-technology content and high-value-added hydrogen-doped pipeline steel products is the inherent demand of Baotou Steel United Co., Ltd. to expand product types on the basis of the existing products. The hydrogen-doped pipeline steel has strict requirements on the resistance to hydrogen-induced cracking (HIC) and sulfide stress corrosion cracking (SCC), and the extremely low sulfur content and low phosphorus content are key indicators for producing the hydrogen-doped pipeline steel.

[0003] Sulfur is easy to form manganese sulfide inclusions in steel, which becomes a sensitive source of HIC cracks and is extremely unfavorable to the resistance to HIC performance. Phosphorus is easy to central segregation, and is easy to form a structure hardening zone in the rolling process, which is extremely unfavorable to the resistance to HIC performance. At present, major steel enterprises mainly adopt converter smelting process for dephosphorization operation. However, with the continuous increase of the phosphorus content of high-phosphorus molten iron and the quality requirements of customers on the materials, the dephosphorization operation of the converter often cannot reach the internal control range, and the remedial measures for the phosphorus content exceeding the standard after the converter smelting are usually point blowing or secondary treatment by returning to the furnace. Whether it is point blowing or secondary treatment, in addition to increasing the production cost, it also reduces the production efficiency, and even leads to the over-oxidation of the molten steel and the deterioration of the cleanliness of the molten steel. In addition, the control of the sulfur content directly affects the crack control results and delivery condition requirements of the hydrogen-doped pipeline steel, and stable control is crucial. SUMMARY

[0004] The purpose of the present application is to provide a high-phosphorus molten iron extremely low-sulfur and low-phosphorus hydrogen-doped pipeline steel smelting process control method, especially a high-phosphorus molten iron smelting low-phosphorus steel and extremely low-sulfur, and the cleanliness of the steel is also greatly improved, and the final oxygen content can be stably controlled within 0.0020%.

[0005] To solve the above technical problems, the present application adopts the following technical scheme:

[0006] The present application relates to a high-phosphorus molten iron extremely low-sulfur and low-phosphorus hydrogen-doped pipeline steel smelting process control method, and the smelting process includes: converter smelting, post-furnace slag washing, LF refining, RH vacuum treatment, and continuous casting, and specifically includes:

[0007] 1) Molten iron conditions: the temperature of the molten iron is greater than or equal to 1350℃, the silicon content of the molten iron is 0.25%-0.70%, the sulfur content of the molten iron is less than or equal to 0.030%, and the phosphorus content of the molten iron is less than or equal to 0.130%;

[0008] 2) KR desulfurization: the desulfurization stirring time is greater than or equal to 15 min, the desulfurizer addition amount is 7.00-7.50 kg / t, the average particle size of the desulfurizer is 1-1.4 mm, and the desulfurization slag is scraped twice.

[0009] 3) Converter control: lime addition amount 36-40 kg / t, light-burned dolomite addition amount 5-10 kg / t, raw dolomite addition amount 15-20 kg / t, adopt full-process argon blowing mode, bottom blowing flow rate 1600-2000 Nm3 / h;

[0010] 4) Converter tapping condition: converter tapping phosphorus content ≤0.008%, tapping temperature ≥1620℃, tapping oxygen content ≤550 ppm;

[0011] 5) Converter post-furnace slag washing: lime addition amount 3.0-3.5 kg / t during tapping, modifier addition amount 0.35-0.45 kg / t, tapping port roundness and tapping time 4-8 min / furnace;

[0012] 6) LF refining: heating argon setting 400 min / L-600 min / L, lime addition amount 8.00-12.00 kg / t, micro-carbon ferro-aluminum addition amount 0.80-1.40 kg / t, aluminum grain addition amount 0.20-0.50 kg / t;

[0013] 7) Final slag component range: R: 5.5-7.0%, T.Fe+MnO ≤1.0%, C / A: 1.5-2.5;

[0014] 8) Steel grade main component range: smelting key carbon content 0.03-0.07%, silicon content 0.10-0.60%, manganese content 1.00-1.80%, phosphorus content ≤0.005%, sulfur content ≤0.0010%, total oxygen content ≤0.0015%.

[0015] Further, the desulfurizer mass percentage mainly includes: CaO ≥90%, CaF2 ≥9%.

[0016] Further, the desulfurizer average particle size is 1.2 mm.

[0017] Further, the desulfurizer: particle size between 0.3-1.2 mm accounts for more than 80%, particle size ≤5% on average in <0.3 mm and >1.2 mm.

[0018] Further, specifically includes:

[0019] 1). Hot metal condition: hot metal temperature 1362℃, hot metal silicon content 0.25%, hot metal sulfur content 0.026%, hot metal phosphorus content 0.122%;

[0020] 2). KR desulfurization: desulfurization stirring time 15 min, desulfurizer addition amount 7.22 kg / t, desulfurization slag skimming twice;

[0021] 3). Converter control: lime addition amount 38.22 kg / t, light-burned dolomite addition amount 7.85 kg / t, raw dolomite addition amount 15.01 kg / t, adopt full process argon blowing mode, bottom blowing flow rate is 1600-2000 Nm 3 / h;

[0022] 4). Converter tapping condition: converter tapping phosphorus content 0.005%, tapping temperature 1625℃, tapping oxygen content 363ppm;

[0023] 5). Converter post-furnace slag washing: lime addition amount 3.20 kg / t during tapping process, modifier addition amount 0.41 kg / t, tapping mouth is round and tapping time is 7.9 min / furnace;

[0024] 6). LF refining: heating argon setting is 550 min / L, lime addition amount 8.27 kg / t, micro-carbon ferroaluminum addition amount 0.97 kg / t, aluminum grain addition amount 0.20 kg / t;

[0025] 7). Final slag component range: R: 6.1%, T.Fe+MnO: 0.7%, C / A: 2.1;

[0026] 8). Steel grade key components: phosphorus content 0.005%, sulfur content 0.0005%, total oxygen content 0.0013%.

[0027] Further, specifically includes:

[0028] 1). Hot metal condition: hot metal temperature 1330℃, hot metal silicon content 0.38%, hot metal sulfur content 0.017%, hot metal phosphorus content 0.127%;

[0029] 2). KR desulfurization: desulfurization stirring time 15 min, desulfurizer addition amount 7.08 kg / t, desulfurization slag is scraped twice;

[0030] 3). Converter control: lime addition amount 38.44 kg / t, light-burned dolomite addition amount 5.75 kg / t, raw dolomite addition amount 19.15 kg / t, adopt full process argon blowing mode, bottom blowing flow rate is 1600-2000 Nm 3 / h;

[0031] 4). Converter tapping condition: converter tapping phosphorus content 0.005%, tapping temperature 1643℃, tapping oxygen content 599ppm;

[0032] 5). Converter post-furnace slag washing: lime addition amount 3.14 kg / t during tapping process, modifier addition amount 0.43 kg / t, tapping mouth is round and tapping time is 7.3 min / furnace;

[0033] 6). LF refining: heating argon is set to 550 min / L, the adding amount of white ash is 11.99 kg / t, the adding amount of micro-carbon aluminum iron is 1.37 kg / t, and the adding amount of aluminum particles is 0.37 kg / t;

[0034] 7). The composition range of final slag is R: 6.4%, T.Fe+MnO: 0.6%, and C / A: 2.2;

[0035] 8). The key components of the steel grade are that the phosphorus content is 0.005%, the sulfur content is 0.0008%, and the total oxygen content is 0.0012%.

[0036] Further, specifically includes:

[0037] 1). Hot metal conditions: hot metal temperature is 1358℃, the silicon content of hot metal is 0.29%, the sulfur content of hot metal is 0.019%, and the phosphorus content of hot metal is 0.124%;

[0038] 2). KR desulfurization: desulfurization stirring time is 15 min, the adding amount of desulfurizer is 7.42 kg / t, and the desulfurization slag is scraped twice;

[0039] 3). Converter control: the adding amount of white ash is 39.21 kg / t, the adding amount of light-burned dolomite is 3.55 kg / t, the adding amount of raw dolomite is 11.51 kg / t, the full-process argon blowing mode is adopted, and the bottom blowing flow is 1600-2000 Nm 3 / h;

[0040] 4). Converter tapping conditions: the phosphorus content of converter tapping is 0.004%, the tapping temperature is 1626℃, and the oxygen content of tapping is 428 ppm;

[0041] 5). Converter post-conversion slag washing: the adding amount of white ash during tapping is 3.40 kg / t, the adding amount of modifier is 0.41 kg / t, the tapping port is round, and the tapping time is 7.6 min / furnace;

[0042] 6). LF refining: heating argon is set to 550 min / L, the adding amount of white ash is 7.74 kg / t, the adding amount of micro-carbon aluminum iron is 1.25 kg / t, and the adding amount of aluminum particles is 0.20 kg / t;

[0043] 7). The composition range of final slag is R: 6.0%, T.Fe+MnO: 0.6%, and C / A: 2.2;

[0044] 8). The key components of the steel grade are that the phosphorus content is 0.004%, the sulfur content is 0.0004%, and the total oxygen content is 0.0006%.

[0045] Compared with the prior art, the beneficial technical effects of the present application are:

[0046] The present application reduces the burden of LF desulfurization by slag treatment after the furnace, effectively improves the yield rate, improves the production efficiency and ensures continuous casting; compared with the conventional production, the desulfurization efficiency is improved, and the cleanliness of the steel is also improved, and the final oxygen content can be stably controlled within 0.0015%. BRIEF DESCRIPTION OF DRAWINGS

[0047] The present application will be further described below in combination with the description of the drawings.

[0048] Figure 1 The implementation flowchart in the steelmaking process is shown. DETAILED DESCRIPTION

[0049] Example 1:

[0050] 1. Hot metal conditions: hot metal temperature 1362℃, hot metal silicon content 0.25%, hot metal sulfur content 0.026%, hot metal phosphorus content 0.122%;

[0051] 2. KR desulfurization: desulfurization stirring time 15min, desulfurizer addition amount 7.22kg / t, desulfurization slag skimming twice;

[0052] 3. Converter control: lime addition amount 38.22kg / t, light-burned dolomite addition amount 7.85kg / t, raw dolomite addition amount 15.01kg / t, using full-process argon blowing mode, bottom blowing flow rate 1600-2000Nm 3 / h;

[0053] 4. Converter tapping conditions: converter tapping phosphorus content 0.005%, tapping temperature 1625℃, tapping oxygen content 363ppm;

[0054] 5. Converter post-furnace slag washing: lime addition amount 3.20kg / t during tapping, modifier addition amount 0.41kg / t, tapping port roundness and tapping time 7.9min / furnace;

[0055] 6. LF refining: heating argon setting 550min / L, lime addition amount 8.27kg / t, micro-carbon ferroaluminum addition amount 0.97kg / t, aluminum grain addition amount 0.20kg / t;

[0056] 7. Final slag composition range: R: 6.1%, T.Fe+MnO: 0.7%, C / A: 2.1;

[0057] 8. Key components of steel grade: phosphorus content 0.005%, sulfur content 0.0005%, total oxygen content 0.0013%.

[0058] Example 2:

[0059] 1. Hot metal conditions: hot metal temperature 1330 °C, hot metal silicon content 0.38%, hot metal sulfur content 0.017%, hot metal phosphorus content 0.127%;

[0060] 2. KR desulfurization: desulfurization stirring time 15 min, desulfurizer addition amount 7.08 kg / t, desulfurization slag skimming twice;

[0061] 3. Converter control: lime addition amount 38.44 kg / t, light-burned dolomite addition amount 5.75 kg / t, raw dolomite addition amount 19.15 kg / t, using full-argon blowing mode, bottom blowing flow rate 1600-2000 Nm 3 / h;

[0062] 4. Converter tapping conditions: converter tapping phosphorus content 0.005%, tapping temperature 1643 °C, tapping oxygen content 599 ppm;

[0063] 5. Converter post-conversion slag washing: lime addition amount 3.14 kg / t during tapping, modifier addition amount 0.43 kg / t, tapping port roundness and tapping time 7.3 min / furnace;

[0064] 6. LF refining: heating argon set to 550 min / L, lime addition amount 11.99 kg / t, micro-carbon ferro-aluminum addition amount 1.37 kg / t, aluminum grain addition amount 0.37 kg / t;

[0065] 7. Final slag composition range: R: 6.4%, T.Fe+MnO: 0.6%, C / A: 2.2;

[0066] 8. Steel grade key components: phosphorus content 0.005%, sulfur content 0.0008%, total oxygen content 0.0012%.

[0067] Example 3:

[0068] 1. Hot metal conditions: hot metal temperature 1358 °C, hot metal silicon content 0.29%, hot metal sulfur content 0.019%, hot metal phosphorus content 0.124%;

[0069] 2. KR desulfurization: desulfurization stirring time 15 min, desulfurizer addition amount 7.42 kg / t, desulfurization slag skimming twice;

[0070] 3. Converter control: lime addition amount 39.21 kg / t, light-burned dolomite addition amount 3.55 kg / t, raw dolomite addition amount 11.51 kg / t, using full-argon blowing mode, bottom blowing flow rate 1600-2000 Nm 3 / h;

[0071] 4. Converter tapping conditions: the phosphorus content of converter tapping is 0.004%, the tapping temperature is 1626℃, and the oxygen content of tapping is 428ppm;

[0072] 5. Converter post-conversion slag washing: the lime addition amount is 3.40kg / t, the modifier addition amount is 0.41kg / t, the tapping port is round, and the tapping time is 7.6min / furnace;

[0073] 6. LF refining: the heating argon is set to 550min / L, the lime addition amount is 7.74kg / t, the micro-carbon ferro-aluminum addition amount is 1.25kg / t, and the aluminum particle addition amount is 0.20kg / t;

[0074] 7. The final slag component range: R: 6.0%, T.Fe+MnO: 0.6%, C / A: 2.2;

[0075] 8. The key components of the steel grade: the phosphorus content is 0.004%, the sulfur content is 0.0004%, and the total oxygen content is 0.0006%.

[0076] Comparative Example 1:

[0077] 1. Hot metal conditions: the hot metal temperature is 1362℃, the silicon content of hot metal is 0.34%, the sulfur content of hot metal is 0.029%, and the phosphorus content of hot metal is 0.117%;

[0078] 2. KR desulfurization: the desulfurization stirring time is 10min, the desulfurizer addition amount is 4.01kg / t, and the desulfurization slag is scraped once;

[0079] 3. Converter control: the lime addition amount is 36.37kg / t, the light-burned dolomite addition amount is 24.33kg / t, the full-range argon blowing mode is adopted, and the bottom blowing flow is 1600-2000Nm 3 / h;

[0080] 4. Converter tapping conditions: the phosphorus content of converter tapping is 0.013%, the tapping temperature is 1631℃, and the oxygen content of tapping is 614ppm;

[0081] 5. Converter post-conversion slag washing: the lime addition amount is 3.72kg / t, the modifier addition amount is 0.75kg / t, the tapping port is round, and the tapping time is 5.1min / furnace;

[0082] 6. LF refining: the heating argon is set to 550min / L, the lime addition amount is 8.31kg / t, and the micro-carbon ferro-aluminum 207 addition amount is 0.77kg / t;

[0083] 7. The final slag component range: R: 5.3%, T.Fe+MnO: 1.1%, C / A: 1.4;

[0084] 8. Steel grade key components: phosphorus content 0.014%, sulfur content 0.0030%, total oxygen content 0.0020%.

[0085] The comparative example does not follow the method of the present application in the converter tapping process and the refining process slagging, and part of the production process does not meet the requirements of the present patent parameters, resulting in the final steel grade composition phosphorus content 0.014%, sulfur content 0.0030%, total oxygen content 0.0020%.

[0086] The above-described embodiments are only to describe the preferred modes of the present application, and not to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A high-phosphorus molten iron low-sulfur, low-phosphorus hydrogen-doped pipeline steel smelting process control method, characterized by comprising: 1) molten iron conditions: molten iron temperature ≥ 1350℃, molten iron silicon content 0.25%-0.70%, molten iron sulfur content ≤ 0.030%, molten iron phosphorus content ≤ 0.130%; 2) KR desulfurization: desulfurization stirring time ≥ 15 min, desulfurizer addition amount 7.00-7.50 kg / t, desulfurizer average particle size 1-1.4 mm, desulfurization slag is scraped twice; 4) converter tapping conditions: converter tapping phosphorus content ≤ 0.008%, tapping temperature ≥ 1620℃, tapping oxygen content ≤ 550 ppm; 3) Converter control: lime addition amount 36-40 kg / t, light-burned dolomite addition amount 5-10 kg / t, raw dolomite addition amount 15-20 kg / t, adopt full-process argon blowing mode, bottom blowing flow rate 1600-2000 Nm 3 / h; 5) converter post-furnace slag washing: lime addition amount during tapping process 3.0-3.5 kg / t, modifier addition amount 0.35-0.45 kg / t, tapping mouth is round and tapping time 4-8 min / furnace; 6) LF refining: heating argon is set to 400 min / L-600 min / L, lime addition amount 8.00-12.00 kg / t, micro-carbon ferro-aluminum addition amount 0.80-1.40 kg / t, aluminum grain addition amount 0.20-0.50 kg / t; 7) final slag component range: R: 5.5-7.0, T.Fe+MnO ≤ 1.0%, C / A: 1.5-2.5; 8) steel grade main component range: smelting key carbon content 0.03-0.07%, silicon content 0.10-0.60%, manganese content 1.00-1.80%, phosphorus content ≤ 0.005%, sulfur content ≤ 0.0010%, total oxygen content ≤ 0.0015%. Desulfurizer mass percentage mainly includes: CaO ≥ 90%, CaF2 ≥ 9%.

2. The high phosphorus molten iron extremely low sulfur, low phosphorus hydrogen-doped pipeline steel steelmaking process control method according to claim 1, characterized by, Desulfurizer average particle size 1.2 mm.

3. The high phosphorus molten iron extremely low sulfur, low phosphorus hydrogen-doped pipeline steel steelmaking process control method according to claim 1, characterized by, The desulfurizer: particle size between 0.3-1.2 mm accounts for more than 80%, particle size ≤ 5% on average in < 0.3 mm and > 1.2 mm.

4. The high phosphorus molten iron extremely low sulfur, low phosphorus hydrogen-doped pipeline steel steelmaking process control method according to claim 1 or 3, characterized by, Specifically comprising:

5. The high phosphorus molten iron extremely low sulfur, low phosphorus hydrogen-doped pipeline steel steelmaking process control method according to claim 1, characterized by, 1) molten iron conditions: molten iron temperature 1362℃, molten iron silicon content 0.25%, molten iron sulfur content 0.026%, molten iron phosphorus content 0.122%; 2) KR desulfurization: desulfurization stirring time 15 min, desulfurizer addition amount 7.22 kg / t, desulfurization slag is scraped twice; 4) converter tapping conditions: converter tapping phosphorus content 0.005%, tapping temperature 1625℃, tapping oxygen content 363 ppm; 3) Converter control: lime addition amount 38.22 kg / t, light-burned dolomite addition amount 7.85 kg / t, raw dolomite addition amount 15.01 kg / t, full-argon blowing mode, bottom blowing flow rate 1600-2000 Nm 3 / h; 5) converter post-furnace slag washing: lime addition amount during tapping process 3.20 kg / t, modifier addition amount 0.41 kg / t, tapping mouth is round and tapping time 7.9 min / furnace; 6) LF refining: heating argon is set to 550 min / L, lime addition amount 8.27 kg / t, micro-carbon ferro-aluminum addition amount 0.97 kg / t, aluminum grain addition amount 0.20 kg / t; 7) final slag component range: R: 6.1, T.Fe+MnO: 0.7%, C / A: 2.1; 8) steel grade key components: phosphorus content 0.005%, sulfur content 0.0005%, total oxygen content 0.0013%. ​

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