Production method of 55 # steel wire rod

Abstract

The invention discloses a production method of a 55 # steel wire rod. The main production process comprises the steps of blast furnace molten iron preparation, molten iron pretreatment, converter top and bottom combined blowing smelting, LF refining, small square billet continuous casting, slow cooling for 48 hours and long material factory rolling. The method comprises the steps of billet heating, high-pressure water descaling, rough rolling, intermediate rolling, finish rolling, cooling water tank control, spinning, stelmor cooling, coil collecting, trimming, sampling inspection, collecting and bundling, weighing and finished wire rod obtaining. And meanwhile, the procedures of converter, refining, continuous casting and rolling are improved to a certain extent. According to the production method of the 55 # steel wire rod, 55 # steel meets the performance requirements of customers, the tensile strength is stabilized to be 800 MPa or above, the percentage elongation after fracture is larger than or equal to 15%, the area reduction rate is larger than or equal to 50%, and the product size and appearance are free of defects.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgy and rolling, and in particular relates to a production method of a 55# steel wire rod. Background Art

[0002] 55# wire rod steel belongs to medium-high carbon steel. After downstream deep processing, it has high surface hardness and strength characteristics. The heat treatment method of downstream deep processing users is basically to use the hot-rolled materials of the steel mill after quenching or normalizing. It is mainly used to manufacture various mechanical parts that require high strength, wear resistance and high elasticity, such as bearings, gears, pins, rims, flat springs, crankshafts and other key parts. 55# steel plays an important role in many industrial fields due to its high strength, wear resistance and good cutting performance. Summary of the invention

[0003] The purpose of the present invention is to provide a production method of 55# steel wire rod, so that 55# steel meets the performance requirements of customers, the tensile strength is stabilized at more than 800MPa, the elongation after fracture is greater than or equal to 15%, the area reduction rate is greater than or equal to 50%, and the product size and appearance have no defects.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] The present invention discloses a production method of 55# steel wire rod, and the main production process includes: blast furnace molten iron - molten iron pretreatment - converter top and bottom blowing smelting - LF refining - small square billet continuous casting - slow cooling for 48 hours - long product mill rolling; billet heating - high-pressure water descaling - rough rolling - intermediate rolling - finishing rolling - controlled cooling water tank - wire laying - Stelmor cooling - coiling - trimming - sampling inspection - collection and bundling - weighing - finished wire rod; specifically:

[0006] Converter:

[0007] Low-high-low gun position control is adopted, and the gun position is 1.1-1.5m; the gas content requirements of the ingot are: O≤40ppm, N≤60ppm; single slag or double slag operation is adopted according to the molten iron conditions, and the terminal basicity is 2.5-3.5; the converter adopts high-drawing supplementary blowing operation, and the final composition of steel tapping C≥0.10%, T≥1610℃; the converter adopts aluminum-free deoxidation process, and the amount of deoxidizer added: silicon calcium barium 190-210kg / furnace, fluorite ball 90-110kg; the deoxidizer addition time is controlled at the beginning of steel tapping, 50s after the steel flow is seen; the alloy addition time is controlled at the beginning of steel tapping, 1min after the steel flow is seen; the bottom blowing before the converter adopts the full-process argon blowing mode, and the converter area adopts low-nitrogen carburizer carbon matching;

[0008] Refining:

[0009] Refining in situ heating for 8min-10min, according to the slag surface of molten steel in situ, add 90-110kg of silicon calcium barium, 0-50kg of fluorite balls, and 100-300kg of lime; in the later stage of refining treatment, ferrosilicon powder is used to adjust the slag, and 90-110kg of quartz sand is added in the later stage of heating. The basicity of the slag out of situ is controlled to be ≤1.7; the argon flow control is adjusted to ensure that the slag liquid surface creeps at the soft blowing argon port;

[0010] Continuous Casting:

[0011] The starting pulling speed is 0.25m / min, the target constant pulling speed is 2.0m / min, and the pulling speed fluctuation range is ±0.1m / min; the water flow rate of each crystallizer is 125-130m3 / h, the water inlet pressure is ≥0.8MPa, the inlet and outlet water temperature difference is 4-8℃, and the secondary cooling water meter adopts gas mist intercooling;

[0012] Steel rolling:

[0013] Rolling temperature control: starting rolling temperature 1000±30℃, finishing rolling temperature 920±20℃, spinning temperature 900±20℃; fan opening degree: 1#-6# fan opening degree 100%, 7#-8# fan opening degree 50%; 9#-10# fan closed; Stellmo roller speed setting is as follows:

[0014]

[0016] Furthermore, the amount of silicon, calcium and barium added should be increased or decreased according to the sulfur in the steelmaking process, and the total amount of silicon, calcium and barium in place should not exceed 200kg to avoid silicon bubbling.

[0017] Furthermore, the secondary cooling water meter adopts mist intercooling, and the K values ​​of zones 1-4 are 1.0, 1.0, 1.0, and 1.0, respectively.

[0018] Furthermore, the chemical composition of the 55# steel wire rod by mass percentage is: C: 0.52-0.060%; Si: 0.17-0.37%; Mn: 0.50-0.80%; P≤0.035%; S: ≤0.035%; the remainder is Fe and a small amount of impurity elements.

[0019] Furthermore, the amount of deoxidizer added is: 200kg / furnace of silicon calcium barium and 100kg of fluorite balls.

[0020] Furthermore, when Si≤0.5, single slag operation is performed for molten iron entering the furnace, and when Si>0.5, double slag operation is performed.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are: DETAILED DESCRIPTION

[0022] A method for producing 55# steel wire rod, comprising:

[0023] Converter improvement plan:

[0024] Low-high-low gun position control is adopted, and the gun position is 1.1~1.5m. Gas content requirements for ingot casting: O≤40ppm, N≤60ppm; single slag or double slag operation is adopted according to the molten iron conditions (it is recommended to operate with single slag when Si≤0.5 for molten iron, and double slag operation when Si>0.5, and the end point basicity is 2.5-3.5; the converter adopts high-draw supplementary blowing operation, and the end point composition of steel tapping C≥0.10%, T≥1610℃; the converter adopts aluminum-free deoxidation process, and the amount of deoxidizer added: silicon calcium barium 200kg / furnace, fluorite ball 100kg. The time of adding deoxidizer is controlled at the beginning of steel tapping, 50s after the steel flow is seen; the time of adding alloy is controlled at the beginning of steel tapping, 1min after the steel flow is seen; the bottom blowing before the converter adopts the full-process argon blowing mode, and the converter area adopts low-nitrogen carburizer carbon matching.

[0025] Refining improvement plan:

[0026] Refining in situ heating for 8min-10min, according to the slag surface of molten steel, add 100kg of silicon calcium barium, 0-50kg of fluorite balls, and 100-300kg of lime. The amount of silicon calcium barium added can be increased or decreased according to the sulfur of steel tapping. The total amount of silicon calcium barium in situ shall not exceed 200kg to avoid silicon bubbling; in the later stage of refining treatment, ferrosilicon powder is used to adjust the slag, and 100kg of quartz sand is added in the later stage of heating. The basicity of the slag out of situ is controlled to be ≤1.7; the argon flow control is adjusted to ensure the creeping of the slag liquid surface at the soft blowing argon port.

[0027] Continuous casting improvement plan:

[0028] The starting pulling speed is 0.25m / min, the target constant pulling speed is 2.0m / min, and the pulling speed fluctuation range is ±0.1m / min; the water flow rate of each flow of the crystallizer is 125-130m3 / h, the water inlet pressure is ≥0.8MPa, the inlet and outlet water temperature difference is 4-8℃, and the secondary cooling water meter adopts mist intercooling (the K values ​​of zones 1-4 are 1.0, 1.0, 1.0, and 1.0 respectively);

[0029] Steel rolling improvement plan:

[0030] Rolling temperature control: starting rolling temperature 1000±30℃, finishing rolling temperature 920±20℃, spinning temperature 900±20℃; fan opening degree: 1#-6# fan opening degree 100%, 7#-8# fan opening degree 50%; 9#-10# fan closed; Stellmo roller speed setting is as follows:

[0031]

[0032] Example:

[0033] 1. Strictly control the oxygen and nitrogen elements of the casting, as shown in the following table:

[0034]

[0035]

[0036] Through the implementation of the steelmaking converter and refining improvement plan, the content of the two gas elements was detected to be significantly reduced and stabilized within a fixed range, which played a great role in ensuring the quality of the continuous casting billet.

[0037] 2. The results of constant pulling speed control are shown in the following table:

[0038]

[0039] Through the implementation of the steelmaking continuous casting improvement plan, the improved continuous casting billet drawing speed is stably controlled, preventing the occurrence of corner cracks, inter-cracks and central shrinkage holes during the continuous casting process.

[0040] 3. The improvement of the stability of the product's mechanical properties is shown in the following table:

[0041]

[0042] Through the implementation of the steel rolling improvement plan, the mechanical properties of the products fully meet the design requirements.

[0043] 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 production method of 55# steel wire rod, the main production process: blast furnace molten iron - molten iron pretreatment - converter top and bottom blowing smelting - LF refining - small square billet continuous casting - slow cooling for 48 hours - long product mill rolling; billet heating - high-pressure water descaling - rough rolling - medium rolling - finishing rolling - controlled cooling water tank - wire laying - Stelmor cooling - coiling - trimming - sampling inspection - collection and bundling - weighing - finished wire rod; characterized in that, Specific: Converter: Low-high-low gun position control is adopted, and the gun position is 1.1-1.5m; the gas content requirements of the ingot are: O≤40ppm, N≤60ppm; single slag or double slag operation is adopted according to the molten iron conditions, and the terminal basicity is 2.5-3.5; the converter adopts high-drawing supplementary blowing operation, and the final composition of steel tapping C≥0.10%, T≥1610℃; the converter adopts aluminum-free deoxidation process, and the amount of deoxidizer added: silicon calcium barium 190-210kg / furnace, fluorite ball 90-110kg; the deoxidizer addition time is controlled at the beginning of steel tapping, 50s after the steel flow is seen; the alloy addition time is controlled at the beginning of steel tapping, 1min after the steel flow is seen; the bottom blowing before the converter adopts the full-process argon blowing mode, and the converter area adopts low-nitrogen carburizer carbon matching; Refining: Refining in situ heating for 8min-10min, according to the slag surface of molten steel in situ, add 90-110kg of silicon calcium barium, 0-50kg of fluorite balls, and 100-300kg of lime; in the later stage of refining treatment, ferrosilicon powder is used to adjust the slag, and 90-110kg of quartz sand is added in the later stage of heating. The basicity of the slag out of situ is controlled to be ≤1.7; the argon flow control is adjusted to ensure that the slag liquid surface creeps at the soft blowing argon port; Continuous Casting: The starting pulling speed is 0.25m / min, the target constant pulling speed is 2.0m / min, and the pulling speed fluctuation range is ±0.1m / min; the water flow rate of each crystallizer is 125-130m3 / h, the water inlet pressure is ≥0.8MPa, the inlet and outlet water temperature difference is 4-8℃, and the secondary cooling water meter adopts gas mist intercooling; Steel rolling: Rolling temperature control: starting rolling temperature 1000±30℃, finishing rolling temperature 920±20℃, spinning temperature 900±20℃; fan opening degree: 1#-6# fan opening degree 100%, 7#-8# fan opening degree 50%; 9#-10# fan closed; Stellmo roller speed setting is as follows:

2. The method for producing 55# steel wire rod according to claim 1, characterized in that: The amount of silicon, calcium and barium added should be increased or decreased according to the sulfur in steelmaking. The total amount of silicon, calcium and barium in place should not exceed 200kg to avoid silicon bubbling.

3. The method for producing 55# steel wire rod according to claim 1, characterized in that: The secondary cooling water meter adopts mist intercooling, and the K values ​​of zones 1-4 are 1.0, 1.0, 1.0, and 1.0 respectively.

4. The method for producing 55# steel wire rod according to claim 1, characterized in that: The chemical composition of the 55# steel wire rod by mass percentage is: C: 0.52-0.060%; Si: 0.17-0.37%; Mn: 0.50-0.80%; P≤0.035%; S: ≤0.035%; the balance is Fe and a small amount of impurity elements.

5. The method for producing 55# steel wire rod according to claim 1, characterized in that: Deoxidizer addition amount: silicon calcium barium 200kg / furnace, fluorite ball 100kg.

6. The method for producing 55# steel wire rod according to claim 1, characterized in that: When Si≤0.5, single slag operation is adopted for molten iron entering the furnace; when Si>0.5, double slag operation is adopted.

Images