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Accelerated cooling process method carried out after steel plate normalizing

A technology of accelerated cooling and process method, which is applied in the cooling field of iron and steel production, which can solve the problems of ferrite grain growth and low steel plate strength, and achieve the effects of improved heat transfer coefficient, high cooling intensity, and wide adjustment range of cooling capacity

Inactive Publication Date: 2010-09-15
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, in the traditional normalizing heat treatment process, after heating and air cooling, the ferrite grains will still grow, resulting in lower strength of the steel plate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The low-carbon bainitic Q460E grade steel plate with a thickness of 4mm and a width of 1200mm is heated to 850°C in a heat treatment furnace for normalizing, and after being released from the furnace, it enters the accelerated cooling area from the conveying roller table for accelerated cooling, and the laminar flow cooling is 0.10MPa , the air mist cooling water pressure is 0.1MPa, the air mist cooling air pressure is 0.15MPa, and the water-air volume ratio of the air mist is 1:3. Combination of air mist cooling and laminar cooling, the cooling speed is controlled at 2°C / s , the final cooling temperature is 400°C, and finally enters the cooling bed to obtain low-carbon bainite Q460E grade steel plate. After normalizing and accelerated cooling, the yield strength reaches 420-460MPa, and the tensile strength reaches 570-620MPa. The ratio is 0.7-0.75, the δ5 elongation rate is 25%-30%, and the Z-direction area reduction rate is 40%-60%.

[0030] Accelerated cooling after ...

Embodiment 2

[0032] According to the technical scheme of the present invention, the ferritic pearlitic steel Q345E steel plate with a thickness of 50mm and a width of 2400mm is heated to 900°C in a normalizing heat treatment furnace, and after being released from the furnace, it enters the accelerated cooling area by the conveying roller table for cooling. Accelerated cooling, the cooling form is a combination of air mist cooling and laminar cooling, the pressure of laminar cooling water is 0.30MPa, the pressure of air mist cooling water is 0.30MPa, the pressure of air mist cooling air is 0.40MPa, the water-air volume ratio of the air mist The ratio is 1:10; the final cooling temperature is controlled at 550°C, and the cooling rate is controlled at 5°C / s. The cooled steel plate finally enters the cooling bed. Compared with the traditional normalized air-cooled steel plate, the mechanical properties of the accelerated cooling Q345E steel plate after normalizing are improved by 30-50MPa in y...

Embodiment 3

[0034] The Q690 steel plate with a thickness of 120mm and a width of 5000mm is heated to 950°C in a normalizing heat treatment furnace. After being released from the furnace, it enters the accelerated cooling area by the conveying roller table for accelerated cooling. The cooling form is gas mist cooling, and the pressure of gas mist cooling water is 0.50MPa, the air mist cooling pressure is 0.60MPa, the water-gas volume ratio of the mist is 1:15; the final cooling temperature is controlled at 700°C, and the cooling speed is controlled at 20°C / s. The cooled steel plate finally enters the cooling bed. Compared with the traditional normalized air-cooled steel plate, the mechanical properties of the accelerated cooling Q690 steel plate after normalizing are improved by 60-100MPa in yield strength, 70-90MPa in tensile strength, improved in low-temperature toughness, and slightly decreased in plasticity.

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Abstract

The invention belongs to cooling technologies carried out after thermal treatment in steel production, and relates to an accelerated cooling process method carried out after steel plate normalizing. In the specific process method, the normalized steel plate with the thickness of 4-120 mm is heated to 850-950 DEG C in a thermal treatment furnace; and then the steel plate is delivered into an accelerated cooling area to cool by a conveying roller bed, wherein the cooling speed is controlled within 2-20 DEG C / s, and the final cooling temperature is controlled within 400-700 DEG C. The cooling method is the combination of aerial fog cooling and laminar flow cooling or the combination of the aerial fog cooling and spraying cooling, wherein the pressure of the laminar cooling water or the spraying cooling water is 0.10-0.50 MPa, the pressure of the air fog cooling water is 0.10-0.60 MPa, and the pressure of the aerial fog cooling gas is 0.15-0.80 MPa. By adopting the steel plate produced by the accelerated cooling process carried out after the normalizing, the structure is obviously refined, the growth of the particles of the precipitated matters is inhibited, the strength and toughness of the steel plate are enhanced, or the equivalent strength and toughness is realized under the condition of less alloy content.

Description

technical field [0001] The invention belongs to the cooling technology of iron and steel production, and in particular relates to a process method of accelerated cooling of a steel plate after normalizing. Background technique [0002] Normalizing heat treatment is to heat the steel to a temperature above the upper critical point (A3) of the ferrite-austenite transformation to about 30-50°C or higher to make the steel austenitized, and after the heat preservation is homogenized, Process of slow cooling in air. The main purpose of normalizing heat treatment is to refine the structure of steel, eliminate the structural defects of steel after thermal deformation, and improve the mechanical properties of steel. [0003] However, in the traditional normalizing heat treatment process, after heating and air cooling, the ferrite grains will still grow, resulting in low strength of the steel plate. If an appropriate accelerated cooling rate is adopted after normalizing, the phase t...

Claims

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Application Information

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IPC IPC(8): C21D1/28C21D9/46
Inventor 余伟何春雨张立杰刘涛韩爽程知松徐言东邓宏玉詹智敏
Owner UNIV OF SCI & TECH BEIJING
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