An economical ∮150 billet low carbon high manganese steel casting machine production quality control process

Abstract

The invention discloses that the purpose of the invention is to provide an economical ∮150 billet type low-carbon high-manganese steel casting machine production quality control process, through the vibration table amplitude frequency, electromagnetic stirring parameters, protective slag model, secondary cooling water distribution, superheat and drawing speed matching parameters, casting machine full process protection pouring, drawing and straightening machine pressure setting, low-carbon covering agent and other parameter settings, low-carbon high-manganese steel ∮150 continuous casting round tube billets with stable quality are obtained.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a production quality control process for an economical ∮150 billet low-carbon high-manganese steel casting machine. Background Art

[0002] Low-carbon high-manganese steel has high strength, good low-temperature impact toughness, and excellent welding performance. It is widely used in shipbuilding, offshore oil platforms, bridges, engineering machinery and other fields. With the prosperity and development of my country's economy, land resources are becoming increasingly scarce, which requires the land economy to develop in coordination with the marine economy and go hand in hand. Against this background, my country's engineering machinery manufacturing industry, shipbuilding industry and offshore oil platform construction have achieved rapid development, and the demand for low-carbon high-manganese steel has increased year by year. However, in recent years, both the engineering machinery manufacturing industry and the shipbuilding industry have faced problems such as prominent contradictions in the industrial structure, overcapacity at the low end, and insufficient high-end capacity, resulting in a large number of companies declining profits and even bankruptcy. Among them, the insufficient supply of some high-performance steel products has led to low technical content of steel and high manufacturing costs, causing many companies to lose their competitive advantages, which is one of the important reasons for being eliminated by the market. To this end, my country has listed marine engineering equipment and high-tech ships as one of the ten key areas of "Made in China 2025", and vigorously supports the development of marine engineering equipment and high-tech ship industries. It can be inferred that in the next 10 years, the development of supporting materials and production technologies related to high-performance low-carbon high-manganese steel will be the research focus of metallurgical workers.

[0003] At present, the domestic production of high manganese steel seamless pipes has gradually adopted the direct tube-threading of continuous casting billets. Although direct tube-threading can avoid a rolling process and improve the yield rate, it has more stringent requirements on the quality of continuous casting billets. With the popularization of the direct tube-threading process of continuous casting billets, the market has higher and higher requirements and expectations for the cross-sectional size, variety and quality of continuous casting round billets.

[0004] Compared with the traditional use of steel ingots to roll round steel, the use of continuous casting round tube billets will greatly improve production efficiency, increase the yield rate, and effectively reduce production costs. Its metal yield rate is high, saving 400 yuan to 800 yuan per ton of steel (excluding tax) compared with the ∮350 billet type to ∮150 billet type. Secondly, the manganese content in the steel is high, the crack tendency is serious, and the production of large billets exacerbates the quality risk. At the same time, the quality risk of low-carbon high-manganese steel is high during the rolling process, and the yield rate is low. However, people who are familiar with the continuous casting process know that the smaller the cross-sectional size of the continuous casting billet, the greater the production difficulty, the more complex the process, and the higher the quality risk. According to data inquiries and records, the current ∮150 size low-carbon high-manganese steel continuous casting round tube billets in China belong to a blank field, and no relevant valuable continuous casting round tube billet information and related research information have been found in the domestic literature search.

[0005] After searching, it was found that there are two literature patents that are most relevant to the technology of the present invention, and the specific contents are described as follows:

[0006] After searching, similar background technologies include: "Round billet and manufacturing process for advanced petroleum casing" (patent application number: 200810152866.9), which is different from the present invention in that: in terms of composition design, the present invention adopts the design concept of low-carbon high-manganese steel, while the similar patents searched adopt the design concept of medium-carbon high-manganese steel. The design steel types are different, and the performance indicators of the products are also different;

[0007] After searching, similar background technologies include: "A method for manufacturing austenitic stainless steel §150 small-size continuous casting round tube billet" (patent application number: 201910948518.0). The difference from the present invention is that the performance indicators of the products are different, the steel composition of this patent, low-carbon high-manganese steel, deviates greatly from the composition of the searched patent, and the production process is also different. Summary of the invention

[0008] The purpose of the present invention is to provide an economical ∮150 billet type low-carbon high-manganese steel casting machine production quality control process, by setting parameters such as vibration table amplitude frequency, electromagnetic stirring parameters, protective slag model, secondary cooling water distribution, superheat and drawing speed matching parameters, casting machine full-process protective pouring, straightening machine pressure setting, low-carbon covering agent, etc., to obtain low-carbon high-manganese steel ∮150 continuous casting round tube billets with stable quality.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] The present invention discloses an economical ∮150 billet low carbon high manganese steel casting machine production quality control process, comprising:

[0011] (1) The temperature of the continuous casting ladle is 1573℃~1588℃, and the temperature of the continuous casting ladle is 1543℃~1558℃;

[0012] (2) Using weak cooling process, the crystallizer vibrates at high frequency and low amplitude;

[0013] (3) The superheat control range is 30℃~50℃, and the superheat is matched with the casting speed control;

[0014] (4) Carry out argon blowing operation on the tundish, long water inlet graphite sealing protection + protective slag + long water inlet argon protection pouring + tundish low-carbon covering agent, keep the crystallizer protective slag and black slag covering throughout the process, and the water distribution coefficient and crystallizer cooling water are controlled as follows:

[0015] Specific water volume: Zone 1 31.2~37.53L / kg; Zone 2 50.04~60.04L / kg; Zone 3 26.3~31.5L / kg; Zone 4 14~21L / kg;

[0016] Crystallizer water: 1800~2200L / min;

[0017] (5) Adopting crystallizer electromagnetic stirring technology; the tensioning and straightening machine uses low-pressure tensioning and straightening, and the electromagnetic stirring parameters are: clockwise stirring, current 80-150A, and frequency 3;

[0018] (6) Requirements for mold slag composition: SiO2 25-35%, CaO 25-35%, MgO 0.5-2.0%, Al2O3 3.5-8%, Fe2O3 0-1%, MnO2 0-2%, Na2O 2.0-6.0%, F 3.0-8.0%, C-tot.15-20%, moisture <1.0%;

[0019] (7) Hot billet pressure parameters of the straightening machine: 2 to 4 bar for 1 straightening machine, 2 to 4 bar for 2 straightening machines, 3 to 7 bar for 3 straightening machines, and 3 to 7 bar for 4 straightening machines.

[0020] Furthermore, the crystallizer vibration control is specifically as follows: the vibration mode is mechanical sine, the vibration fundamental frequency is 30 to 300 times / minute, and the vibration amplitude is 4 to 5 mm.

[0021] Furthermore, the matching of superheat and pulling speed control is specifically as follows: when the superheat control range is 30°C to 40°C, the pulling speed is 2.2 to 2.4 m / min; when the superheat control range is 40°C to 50°C, the pulling speed is 2.0 to 2.2 m / min.

[0022] Furthermore, the components of the low-carbon covering agent are calculated by mass percentage as follows: TC 1.0-2.5%, CaO 25.0-35.0%, SiO2 35-45%, Al2O3 15-20%, and MgO 2.0-4.0%.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] By setting the process parameters of the present invention, there are no visible scars, slag inclusions, pores, pinholes, and cracks with a depth of more than 0.5 mm on the surface of the low-carbon high-manganese steel ∮150 continuous casting round tube billet, and the out-of-roundness is ≤6.75 ​​mm; there are no visible white spots, stratification, or inclusions on the low-magnification acid leaching sample of the ingot; the center looseness is ≤1.5 level, and the center shrinkage cavity is ≤1.5 level;

[0025] After testing, the oxygen and nitrogen contents in low carbon high manganese steel ∮150 continuous casting round tube billet are as follows: oxygen content ≤20ppm, nitrogen content ≤60ppm. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 This is the surface photo of the sample after acidification of the ∮150 billet;

[0028] Figure 2 This is a cross-sectional photograph of the sample after acidification of the ∮150 ingot. DETAILED DESCRIPTION

[0029] The chemical composition design of low carbon high manganese steel ∮150 continuous casting round tube billet is shown in Table 1.

[0030] Table 1 Chemical composition test results of low carbon high manganese steel ∮150 continuous casting round tube billet (Wt%)

[0031]

[0032] (1) The temperature of the continuous casting ladle is 1573℃~1588℃, and the temperature of the continuous casting ladle is 1543℃~1558℃.

[0033] (2) A weak cooling process is adopted, and the crystallizer vibrates at high frequency and low amplitude. The crystallizer vibration control is shown in Table 2.

[0034] Table 2 Crystallizer vibration control of low carbon high manganese steel ∮150 continuous casting round tube billet

[0035] Vibration mode Fundamental frequency of vibration, times / minute Vibration amplitude, mm Mechanical sine 30～300 4～5

[0036] (3) The superheat control range is 30℃~55℃. The superheat and casting speed control are shown in Table 3.

[0037] Table 3 Superheat and casting speed control of low carbon high manganese steel ∮150 continuous casting round tube billet

[0038] Superheat℃ 30～40 40～50 Pulling speed, m / min 2.2～2.4 2.0～2.2

[0039] (4) Perform argon blowing in the tundish, long water nozzle graphite sealing protection + protective slag + long water nozzle argon protection pouring + tundish low carbon covering agent, keep the crystallizer protective slag and black slag covering throughout the process, the water distribution coefficient and the crystallizer cooling water control are shown in Table 4.

[0040] Table 4 Crystallizer vibration control of low carbon high manganese steel ∮150 continuous casting round tube billet

[0041]

[0042] (5) Use crystallizer electromagnetic stirring technology; the tensioning and straightening machine uses low pressure tensioning and straightening. The electromagnetic stirring parameters are shown in Table 5

[0043] Table 5 Electromagnetic stirring parameter control of low carbon high manganese steel ∮150 continuous casting round tube billet

[0044] Mixing method Current frequency Clockwise 80～150 3

[0045] (6) The mold slag composition is shown in Table 6

[0046] Table 6 Requirements for the composition of protective slag for continuous casting of low carbon high manganese steel ∮150 round tube billet

[0047]

[0048]

[0049] (7) The hot billet pressure parameters of the straightening machine are shown in Table 7

[0050] Table 7 Hot billet pressure parameter control of low carbon high manganese steel ∮150 continuous casting round tube billet straightening machine

[0051] Tension leveling machine 1 tensioning and leveling machine 2 tensioning and leveling machines 3 tensioning and leveling machines 4 tensioning and leveling machines Hot billet pressure (bar) 2～4 2～4 3～7 3～7

[0052] (8) The composition of the low carbon covering agent is shown in Table 8

[0053] Table 8 Requirements for low carbon covering agent composition of low carbon high manganese steel ∮150 continuous casting round tube billet (Wt%)

[0054]

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention.

[0056] Example 1

[0057] (1) The liquidus temperature of low carbon high manganese steel is about 1513℃, the temperature of continuous casting ladle is 1582℃, and the temperature of continuous casting ladle is 1550℃.

[0058] (2) Crystallizer vibration control is shown in Table 10

[0059] Table 10 Example 1 Crystallizer Vibration Control

[0060] Vibration mode Fundamental frequency of vibration, times / minute Vibration amplitude, mm Mechanical sine 134 4.5

[0061] (3) Superheat and casting speed control are shown in Table 11

[0062] Table 11 Superheat and casting speed control of Example 1

[0063] Superheat℃ 48 38 Pulling speed, m / min 2.0 2.3

[0064] (4) Water distribution coefficient and crystallizer cooling water control are shown in Table 12

[0065] Table 12 Example 1 Crystallizer Vibration Control

[0066]

[0067] (5) Electromagnetic stirring parameters are shown in Table 13

[0068] Table 13 Electromagnetic stirring parameter control of Example 1

[0069] Mixing method Current frequency Clockwise 100 3

[0070] (6) The mold slag composition control table 14 shows

[0071] Table 14 Example 1 slag composition control

[0072]

[0073] (7) The hot billet pressure parameters of the straightening machine are shown in Table 15

[0074] Table 15 Example 1 Hot billet pressure parameters Parameter control of the straightening machine

[0075] Tension leveling machine 1 tensioning and leveling machine 2 tensioning and leveling machines 3 tensioning and leveling machines 4 tensioning and leveling machines Hot billet pressure (bar) 2.1 2.0 2.9 3.1

[0076] (8) The composition of the low carbon covering agent is shown in Table 16

[0077] Table 16 Example 1 Lowering carbon covering agent composition control (Wt%)

[0078] Main Elements TC CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO Low carbon covering agent 1.32 30.24 39.80 16.87 2.93

[0079] (9) Example 1 Continuous Casting Round Tube Billet Casting Quality Control

[0080] 1. Surface quality: There are no visible scars, slag inclusions, pores, pinholes, or cracks with a depth exceeding 0.5 mm on the surface of the continuous casting billet, and the out-of-roundness is less than 6.75 mm;

[0081] 2. Low magnification of continuous casting billet: There are no visible white spots, stratification, or inclusions on the low magnification acid leaching sample of the continuous casting billet; the center looseness is 1.0 level, and the center shrinkage cavity is 1.0 level;

[0082] 3. Hydrogen, oxygen and nitrogen content in steel: [H]: 1.6ppm; [O]: 16ppm, [N] 48ppm;

[0083] 4. The chemical composition test results of the continuous casting round tube billet of Example 2 are shown in Table 17

[0084] Table 17 Melting composition test results of Example 1 (Wt%)

[0085]

[0086] 5. As shown in Table 18, the results of the spot check of the out-of-roundness of the casting are in line with the national standard YB / T4149-2008, with a diameter of ≤150mm and an out-of-roundness of <4.5%d (6.75mm).

[0087] Table 18 Out-of-roundness control of continuous casting round tube billet in Example 1

[0088] Runner 1 stream 2 Stream 3 Stream 4 Stream 5. Stream Inner and outer arc (mm) 149 148 149 150 149 North and south (mm) 151 152 154 154 153 Out-of-roundness value (mm) 2 4 5 4 4

[0089] Example 2

[0090] (1) The temperature of the continuous casting ladle is 1579℃, and the temperature of the continuous casting ladle is 1553℃;

[0091] (2) Crystallizer vibration control is shown in Table 19

[0092] Table 19 Crystallizer vibration control of continuous casting round tube billet in Example 2

[0093] Vibration mode Fundamental frequency of vibration, times / minute Vibration amplitude, mm Mechanical sine 160 4.5

[0094] (3) Superheat and casting speed control are shown in Table 20

[0095] Table 20 Superheat and casting speed control of continuous casting round tube billet in Example 2

[0096]

[0097]

[0098] (4) Water distribution coefficient and crystallizer cooling water control are shown in Table 21

[0099] Table 21 Crystallizer vibration control of continuous casting round tube billet in Example 2

[0100]

[0101] (5) Electromagnetic stirring parameters are shown in Table 22

[0102] Table 22 Electromagnetic stirring parameter control of continuous casting round tube billet in Example 2

[0103] Mixing method Current frequency Clockwise 100 3

[0104] (6) The mold slag composition control table 23 shows

[0105] Table 23 Control of the protective slag composition of the continuous casting round tube billet in Example 2

[0106]

[0107] (7) The hot billet pressure parameters of the straightening machine are shown in Table 24

[0108] Table 24 Parameter control of hot billet pressure parameters of the straightening machine for continuous casting round tube billet in Example 2

[0109] Tension leveling machine 1 tensioning and leveling machine 2 tensioning and leveling machines 3 tensioning and leveling machines 4 tensioning and leveling machines Hot billet pressure (bar) 1.9 2.1 3.0 3.1

[0110] (8) The composition of the low carbon covering agent is shown in Table 25

[0111] Table 25 Example 2 Continuous Casting Round Pipe Billet Drawing Low Carbon Covering Agent Composition Control (Wt%)

[0112] Main Elements TC CaO <![CDATA[SiO2]]> <![CDATA[Al2O3]]> MgO / % Low carbon covering agent 1.14 28.49 41.83 17.13 2.68

[0113] (9) Example 2 Continuous Casting Round Tube Billet Casting Quality Control

[0114] 1. Surface quality: There are no visible scars, slag inclusions, pores, pinholes, or cracks with a depth exceeding 0.5 mm on the surface of the continuous casting billet, and the out-of-roundness is less than 6.75 mm;

[0115] 2. Low magnification of continuous casting billet: There are no visible white spots, stratification, or inclusions on the low magnification acid leaching sample of the continuous casting billet; the center looseness is 1.0 level, and the center shrinkage cavity is 1.0 level;

[0116] 3. Hydrogen, oxygen and nitrogen content in steel: [H]: 2.0ppm; [O]: 18ppm, [N] 55ppm;

[0117] 4. The chemical composition test results of the continuous casting round tube billet in Example 2 are shown in Table 26.

[0118] Table 26 Melting composition test results of Example 2 (Wt%)

[0119]

[0120] 5. As shown in Table 27, the results of the non-roundness spot check meet the national standard YB / T4149~2008, diameter ≤150mm, non-roundness <4.5%d (6.75mm).

[0121] Table 27 Out-of-roundness control of continuous casting round tube billet in Example 2

[0122] Runner 1 stream 2 Stream 3 Stream 4 Stream 5. Stream Inner and outer arc (mm) 148 149 148 151 148 North and south (mm) 154 152 153 153 153 Out-of-roundness value (mm) 6 3 5 3 5

[0123] When steel is produced in 200 section, the ingot may crack in cold state. The 150 section is smaller than the 200 section, with a specific gravity ratio of 56.37%, and the difficulty coefficient of operation and control is large. Through the process parameter setting of the present invention, there are no visible scars, slag inclusions, pores, pinholes, and cracks with a depth exceeding 0.5mm on the surface of the low-carbon high-manganese steel ∮150 continuous casting round tube billet, and the out-of-roundness is ≤6.75mm; there are no visible white spots, stratification, or inclusions on the low-power acid leaching sample of the ingot; the center looseness is ≤1.5 level, and the center shrinkage cavity is ≤1.5 level. Figure 1 (This type of steel has a more serious tendency to crack, which is its characteristic, and there was no 150 section before) and Figure 2 shown.

[0124] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An economical ∮150 billet low carbon high manganese steel casting machine production quality control process, characterized in that: include: (1) The temperature of the continuous casting ladle is 1573℃-1588℃, and the temperature of the continuous casting ladle is 1543℃-1558℃; (2) Using a weak cooling process, the crystallizer vibrates at a high frequency and low amplitude. The crystallizer vibration control is as follows: the vibration mode is mechanical sine, the vibration fundamental frequency is 30-300 times / minute, and the vibration amplitude is 4-5 mm; (3) The superheat control range is 30℃-50℃, and the superheat is matched with the pulling speed control. The matching of superheat and pulling speed control is as follows: when the superheat control range is 30℃-40℃, the pulling speed is 2.2-2.4m / min, and when the superheat control range is 40℃-50℃, the pulling speed is 2.0-2.2m / min; (4) Carry out argon blowing operation on the tundish, long water nozzle graphite sealing protection + protective slag + long water nozzle argon protection pouring + tundish low carbon covering agent, the composition of the low carbon covering agent is calculated by mass percentage as follows: TC 1.0-2.5%, CaO 25.0-35.0%, SiO235-45%, Al2O3 15-20%, MgO 2.0-4.0%; keep the crystallizer protective slag and black slag covering throughout the process, and the water distribution coefficient and crystallizer cooling water are controlled as follows: Specific water volume: Zone 1 31.2-37.53 L / kg; Zone 2 50.04-60.04 L / kg; Zone 3 26.3-31.5 L / kg; Zone 4 14-21 L / kg; Crystallizer water: 1800-2200L / min; (5) Adopting crystallizer electromagnetic stirring technology; the tension and straightening machine uses low-pressure tension and straightening, and the electromagnetic stirring parameters are: clockwise stirring, current 80-150A, frequency 3; (6) Requirements for mold slag composition: SiO2 25-35%, CaO 25-35%, MgO 0.5-2.0%, Al2O3 3.5-8%, Fe2O3 0-1%, MnO2 0-2%, Na2O 2.0-6.0, F 3.0-8.0%, C-tot.15-20%, moisture <1.0%; (7) Hot billet pressure parameters of the straightening machine: 2-4 bar for 1 straightening machine, 2-4 bar for 2 straightening machines, 3-7 bar for 3 straightening machines, and 3-7 bar for 4 straightening machines.

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