Production method of V microalloyed mining wear-resistant steel

Abstract

The invention discloses a production method of V microalloyed mining wear-resistant steel. The production method comprises the following steps: 1) converter production; (2) LF furnace production is conducted, the refining in-place temperature of an LF furnace is 1541-1555 DEG C, and the average refining in-place temperature is 1544 DEG C; the refining off-location temperature is 1559-1580 DEG C, and the average temperature is 1577 DEG C; the refining treatment time is 48-681 minutes, and the average refining treatment time is 53 minutes; (3) VD furnace production is conducted, the deep vacuum time of VD furnace smelting is required to be longer than 13 min, the deep vacuum degree is required to be smaller than or equal to 0.10 Kpa, the soft blowing time is 14-15 min, and the average time is 14 min; the soft blowing flow is 60-170 N1 / min, and the average soft blowing flow is 140 N1 / min; the upper temperature is 1510-1524 DEG C, and the average temperature is 1516 DEG C; 4) continuous casting production; the range of the chemical components is also limited. On the premise of an existing process route, a specific smelting process and narrow component control are adopted, and the rolling steel meeting the requirement for mining wear-resistant steel of customers is produced.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method of V microalloyed wear-resistant steel for mining. Background Art

[0002] Wear-resistant balls are also called wear-resistant media for grinding machines. They are widely used in ball mills in industries such as metallurgy and mining, cement and building materials, thermal power generation, flue gas desulfurization, magnetic materials, chemicals, water-coal slurry, pelletized ore, slag, ultrafine powder, fly ash, calcium carbonate, quartz sand, etc. It is a consumable product, and its main purpose is to grind materials to make them finer to meet the use standards.

[0003] Wear-resistant steel is used as the grinding medium. During service, the regularly arranged grinding balls work in a cascading manner. Through the impact and crushing of the steel balls themselves, the minerals in the gaps are ground to a qualified particle size. At the same time, they are worn by the minerals, continuously lost, and their size becomes smaller, in order to further increase the service life of the steel balls and improve their comprehensive performance.

[0004] Adding an appropriate amount of V microalloying to hot-rolled steel balls can improve the structure of wear-resistant steel, inhibit crack propagation, and improve the comprehensive performance of contact wear resistance under load. At the same time, reasonable heating process and rolling process are important measures to ensure product quality. Under the requirement of product compression ratio, the use of reasonable continuous casting billet, heating process and rolling process is an important means to ensure the product quality of steel for hot-rolled steel balls in ball mills. Summary of the invention

[0005] The purpose of the present invention is to provide a method for producing V microalloyed wear-resistant steel for mining. Under the premise of the existing process route, a specific smelting process and narrow component control are adopted to produce rolling steel that meets the needs of customers for mining wear-resistant steel.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for producing V microalloyed wear-resistant steel for mining, comprising:

[0008] 1) Converter production

[0009] Requirements for hot metal for converter: phosphorus content less than or equal to 0.13% by mass, sulfur content less than or equal to 0.050% by mass; lime, dolomite and fluorite are added as slag-making auxiliary materials during converter smelting, and ferrosilicon, silicon manganese and aluminum silicon manganese are added for deoxidation and alloying according to composition requirements during steelmaking;

[0010] The mass percentage carbon content, phosphorus content and tapping temperature of the molten steel at the converter end point are as follows:

[0011] Steel tapping temperature 1608-1662℃, average 1618℃; carbon content 0.06-0.12%, average 0.08%; phosphorus content 0.010-0.018%, average 0.015%;

[0012] 2) LF furnace production

[0013] The LF furnace refining in-situ temperature is 1541-1555℃, with an average of 1544℃; the refining out-of-situ temperature is 1559-1580℃, with an average of 1577℃; the refining treatment time is 48-681min, with an average of 53min;

[0014] 3) VD furnace production

[0015] The molten steel is then vacuum degassed in a VD furnace to further reduce the harmful gas content in the steel and improve the cleanliness of the steel. The gas content requirements are: [O] ≤ 20ppm; [N] ≤ 80ppm; [H] ≤ 2.5ppm; silicon calcium wire is fed to denature inclusions; the deep vacuum time of VD furnace smelting is required to be greater than 13min, the deep vacuum degree is ≤ 0.10Kpa, the soft blowing time is 14-15min, and the average is 14min; the soft blowing flow rate is 60-170Nl / min, and the average is 140Nl / min; the upper stage temperature is 1510-1524℃, and the average is 1516℃;

[0016] 4) Continuous casting production

[0017] In continuous casting production, the superheat is controlled between 18-30℃, and the casting speed is between 0.65m / min-0.67m / min; the continuous casting billet is slowly cooled for more than 48 hours after it leaves the production line;

[0018] Its chemical components by mass percentage are: C 0.90-0.95%, Si 0.15-0.35%, Mn 0.85-1.10%, P≤0.020%, S≤0.010%, Al≤0.060%, Cr 0.95-1.10%, V 0.04-0.10%, and the rest are Fe and unavoidable impurities.

[0019] Furthermore, its chemical components by mass percentage are: C 0.91%, Si 0.20%, Mn 0.92%, P 0.014%, S 0.006%, Al 0.004%, Cr 0.79%, V 0.05%, and the rest are Fe and inevitable impurities.

[0020] Furthermore, its chemical components are as follows by mass percentage: C 0.95%, Si 0.52%, Mn 0.98%, P 0.020%, S 0.010%, Al 0.006%, Cr 0.86%, V 0.06%, and the rest are Fe and inevitable impurities.

[0021] Furthermore, its chemical components by mass percentage are: C 0.93%, Si 0.28%, Mn 0.95%, P 0.017%, S 0.010%, Al 0.005%, Cr 0.84%, V 0.05%, and the rest are Fe and inevitable impurities.

[0022] Furthermore, 0-60kg of calcium carbide and 0-75kg of fluorite are added.

[0023] Further, the alloy is fine-tuned according to the refined in-situ composition: 0-110kg ferromanganese, 0-50kg ferrosilicon, 180-400kg high carbon ferrochrome, and 150m of aluminum wire are fed.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are:

[0025] Based on the existing process route, we adopt specific smelting technology and narrow composition control to produce rolling steel that meets customers' mining wear-resistant steel requirements. DETAILED DESCRIPTION

[0026] The industrial production process is briefly described as follows:

[0027] Converter smelting—(LF) ladle furnace refining—(VD) vacuum degassing—continuous casting (280*380mm)—special steel rolling.

[0028] More than 10 furnaces have been produced industrially, and the specific process parameters are controlled as follows:

[0029] 1) Converter production

[0030] During converter smelting, 3200-4100kg of lime, 1300-1800kg of dolomite and 1000-2000kg of iron sheet are added according to actual conditions, and silicon manganese and ferrosilicon are added during the steelmaking process.

[0031] The carbon content, phosphorus content (mass percentage) and tapping temperature of the molten steel at the converter end point are shown in Table 1.

[0032] Table 1 Composition and temperature of steel tapping from converter

[0033] Steel tapping temperature ℃ Carbon content% Phosphorus content of steel % Minimum 1608 0.06 0.010 Maximum 1662 0.12 0.018 average value 1618 0.08 0.015

[0034] 2) LF furnace production

[0035] LF furnace refining adds auxiliary materials to make slag according to the composition and temperature changes of molten steel, and adds alloys for fine-tuning and temperature-raising operations. Add 0-60kg of calcium carbide, 0-75kg of fluorite, and fine-tune the alloy according to the refining composition. 0-110kg of ferromanganese, 0-50kg of ferrosilicon, 180-400kg of high-carbon ferrochrome, and 150m of aluminum wire are fed. The molten steel temperature and processing time are shown in Table 2.

[0036] Table 2 Refining LF furnace temperature control

[0037] Refining temperature ℃ Refining temperature℃ Refining treatment time min Minimum 1541 1569 48 Maximum 1555 1580 68 average value 1544 1577 53

[0038] 3) VD furnace production

[0039] After LF refining in the ladle, the molten steel is vacuum degassed in the VD furnace to further reduce the harmful gas content in the steel and improve the cleanliness of the steel. The gas content requirements are: [O] ≤ 20ppm; [N] ≤ 90ppm; [H] ≤ 2.5ppm. After refining, the silicon calcium wire is fed for 150m to denature the inclusions. The deep vacuum time of VD furnace smelting is required to be greater than or equal to 13min. Other process parameters are shown in Table 3.

[0040] Table 3 Refining VD furnace process control

[0041] Soft blowing time min Soft blowing flow rate Nl / min Temperature on stage ℃ Minimum 14 60 1510 Maximum 15 170 1524 average value 14 140 1516

[0042] 4) Continuous casting production

[0043] In continuous casting production, the superheat is controlled between 18-30°C, the casting speed is between 0.65m / min-0.67m / min, and the composition (mass percentage) of the molten steel is controlled as shown in Table 4.

[0044] Table 4 Finished product composition (%)

[0045] C Si Mn P S Al Cr V Minimum 0.91 0.20 0.92 0.014 0.006 0.004 0.79 0.05 Maximum 0.95 0.52 0.98 0.020 0.010 0.006 0.86 0.06 average value 0.93 0.28 0.95 0.017 0.010 0.005 0.84 0.05

[0046] 5) Surface quality

[0047] The continuous casting billet was slowly cooled for more than 48 hours, and no surface cracks or other defects were found on the surface of the continuous casting billet, which fully met the surface quality requirements for the production of hot-rolled round steel.

[0048] 6) Related performance

[0049] 6.1 Rockwell hardness

[0050] In view of the use characteristics and user inspection items of mining wear-resistant steel, the hardness performance inspection of hot-rolled and heat-treated states is added. The heat treatment process is: 800 quenching + 550 tempering. The specific inspection results are shown in Table 5 below.

[0051] Table 5 Rockwell hardness test results (hot rolled state)

[0052]

[0053]

[0054] 6.2 Non-metallic inclusions and grain size

[0055] Table 6 Non-metallic inclusions Unit: Grade

[0056]

[0057] 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. A method for producing V microalloyed wear-resistant steel for mining, characterized in that: include: 1) Converter production Requirements for hot metal for converter: phosphorus content less than or equal to 0.13% by mass, sulfur content less than or equal to 0.050% by mass; During the converter smelting process, lime, dolomite and fluorite are added as slag-making auxiliary materials. During the steel-making process, ferrosilicon, silicon-manganese and aluminum-silicon-manganese are added according to the composition requirements for deoxidation and alloying. The mass percentage carbon content, phosphorus content and tapping temperature of the molten steel at the converter end point are as follows: Steel tapping temperature 1608-1662℃, average 1618℃; carbon content 0.06-0.12%, average 0.08%; phosphorus content 0.010-0.018%, average 0.015%; 2) LF furnace production The LF furnace refining in-situ temperature is 1541-1555℃, with an average of 1544℃; the refining out-of-situ temperature is 1559-1580℃, with an average of 1577℃; the refining treatment time is 48-681min, with an average of 53min; 3) VD furnace production The molten steel is then vacuum degassed in a VD furnace to further reduce the harmful gas content in the steel and improve the cleanliness of the steel. The gas content requirements are: [O] ≤ 20ppm; [N] ≤ 80ppm; [H] ≤ 2.5ppm; silicon calcium wire is fed to denature inclusions; the deep vacuum time of VD furnace smelting is required to be greater than 13min, the deep vacuum degree is ≤ 0.10Kpa, the soft blowing time is 14-15min, and the average is 14min; the soft blowing flow rate is 60-170Nl / min, and the average is 140Nl / min; the upper stage temperature is 1510-1524℃, and the average is 1516℃; 4) Continuous casting production In continuous casting production, the superheat is controlled between 18-30℃, and the casting speed is between 0.65m / min-0.67m / min; the continuous casting billet is slowly cooled for more than 48 hours after it leaves the production line; Its chemical components by mass percentage are: C 0.90-0.95%, Si 0.15-0.35%, Mn 0.85-1.10%, P≤0.020%, S≤0.010%, Al≤0.060%, Cr 0.95-1.10%, V 0.04-0.10%, and the rest are Fe and unavoidable impurities.

2. The method for producing V microalloyed wear-resistant steel for mining according to claim 1, characterized in that: Its chemical components by mass percentage are: C 0.91%, Si 0.20%, Mn 0.92%, P 0.014%, S 0.006%, Al 0.004%, Cr 0.79%, V 0.05%, and the rest are Fe and inevitable impurities.

3. The method for producing V microalloyed wear-resistant steel for mining according to claim 1, characterized in that: Its chemical components by mass percentage are: C 0.95%, Si 0.52%, Mn 0.98%, P 0.020%, S 0.010%, Al 0.006%, Cr 0.86%, V 0.06%, and the rest are Fe and inevitable impurities.

4. The method for producing V microalloyed wear-resistant steel for mining according to claim 1, characterized in that: Its chemical components by mass percentage are: C 0.93%, Si 0.28%, Mn 0.95%, P 0.017%, S 0.010%, Al 0.005%, Cr 0.84%, V 0.05%, and the rest are Fe and inevitable impurities.

5. The method for producing V microalloyed wear-resistant steel for mining according to claim 1, characterized in that: Add 0-60kg of calcium carbide and 0-75kg of fluorite.

6. The method for producing V microalloyed wear-resistant steel for mining according to claim 1, characterized in that: The alloy is fine-tuned according to the refined composition: 0-110kg ferromanganese, 0-50kg ferrosilicon, 180-400kg high carbon ferrochrome, and 150m of aluminum wire are fed.

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