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Secondary cooling method for controlling surface-layer solidification structure of continuous cast slab

A technology of solidification structure and secondary cooling, applied in the field of continuous casting slab surface cooling, can solve the problems of process parameters and control methods, the effect of industrial production is not reported, and achieve the effects of reducing crack sensitivity, improving plasticity and avoiding cracks.

Active Publication Date: 2010-12-15
SHOUGANG CORPORATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

There are very few studies on improving the high-temperature plasticity of steel by controlling precipitates and solidification structures. Dr. Kato from Sumitomo Metal has studied the relevant mechanism in experiments and experimental small casting machines, but the specific process parameters, control methods and industrial production effects are not no report

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0012] When a domestic factory was pouring a 220mm thick slab, transverse cracks appeared on the east and west sides of the inner arc of the slab, and the secondary cooling method was reformulated by the present invention.

[0013] The steel type is Q345R, the section size is 1800mm×220mm, the mold immersion nozzle insertion depth is 150mm, the nozzle angle is 15°C, and the casting speed is 1.02m / min. The secondary cooling setting is: after the slab exits the crystallizer, a strong cooling method is adopted in the vertical section of the casting machine, the water volume of the wide side is increased by 2.2 times, and the water volume is 280L / min, and the water volume of the narrow side is increased by 2.3 times, and the water volume is 78L / min. The temperature is 5.5°C / S, and the running time is 60S. Then use a 0.65L / kg specific water meter for pouring.

[0014] The cast slab off-line was inspected, and the surface structure of the slab was dense, and no crack defects were f...

example 2

[0016] When a domestic factory was pouring a 220mm thick slab, transverse cracks appeared in the 1 / 4 position of the inner arc width direction of the casting slab, and the secondary cooling method was reformulated by the present invention.

[0017] The steel type is Q345-Z25, the section size is 2000mm×250mm, the mold immersion nozzle insertion depth is 155mm, the nozzle angle is 15°C, and the casting speed is 1.0m / min. The secondary cooling setting is: after the slab exits the crystallizer, a strong cooling method is adopted in the vertical section of the casting machine. The water volume of the wide side is increased by 3 times, and the water volume is 381L / min, and the water volume of the narrow side is increased by 2.6 times, and the water volume is 88L / min. Cooling speed It is 6.7℃ / S, and the running time is 60S. Then use a 0.6L / kg specific water meter for pouring.

[0018] The cast slab off-line was inspected, and the surface structure of the slab was dense, and no crac...

example 3

[0020] When a domestic factory was pouring a 250mm thick slab, transverse cracks appeared at a position 300-500mm away from the edge in the width direction of the inner arc of the slab. The secondary cooling method was reformulated by the present invention.

[0021] The steel grade is SS400, the section size is 1800mm×220mm, the mold immersion nozzle insertion depth is 155mm, the nozzle angle is 15°C, and the casting speed is 1.05m / min. The secondary cooling setting is: after the slab exits the crystallizer, the forced cooling method is adopted in the vertical section of the casting machine, the water volume of the wide side is increased by 3.3 times, and the water volume is 419L / min, and the water volume of the narrow side is increased by 2.9 times, and the water volume is 98L / min. It is 8.3°C / S, and the running time is 60S. Then use a 0.56L / kg specific water meter for pouring.

[0022] The cast slab off-line was inspected, and the surface structure of the slab was dense, an...

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Abstract

The invention relates to a secondary cooling method for effectively controlling the surface-layer solidification structure of a continuous cast slab. After the continuous cast slab is discharged out of a crystallizer, the casting machine vertical section is cooled at the cooling speed of 3-10 DEG C / s for 50-160 s, the secondary cooling water quantity in the cooling section corresponding to the time period is increased to 2-5 times larger than the original water quantity, i.e. the broadside water quantity is 260-600 L / min, and the narrow side water quantity is 50-125 L / min. After the intensive cooling of the casting machine vertical section is finished, the subsequent cooling sections adopt the secondary cooling mode with the specific water flow of 0.55-0.8 L / kg. Shown by practices, the surface-layer structure of the cast slab poured in the secondary cooling mode is compact, the grain size is 10-100 mum, precipitates at grain boundary are few and uniform, and the original austenite grain boundary at high temperature is not obvious. High-temperature plasticity tests on steel show that the plasticity of the steel is obviously improved, which is beneficial to elimination of crack defects of the cast slab.

Description

technical field [0001] The invention relates to a continuous casting slab surface cooling method, in particular to a secondary cooling method for effectively controlling the solidification structure on the continuous casting slab surface. Effective control of the solidification structure and the position and distribution of precipitates on the surface of the slab improves the high-temperature plasticity of the steel and helps eliminate crack defects in the slab. Background technique [0002] Surface cracks of continuous casting slabs have always been an important and difficult point in the metallurgical field. Taking angle transverse cracks and surface transverse cracks as examples, scholars have carried out a lot of fruitful research work for many years, but they have not been completely solved. The mechanism of slab transverse cracks has basically been agreed: under the strain rate of continuous casting, there are two low plastic zones in the solidification process of stee...

Claims

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Application Information

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IPC IPC(8): B22D11/22B22D11/124
Inventor 刘洋王文军姜中行吕延春王海宝李战军朱志远王玉龙李景光危耀环杨国伟关春阳
Owner SHOUGANG CORPORATION
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