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Secondary Cooling Method for Controlling Transverse Cracks in Corner of Microalloyed Steel Slabs

A technology of secondary cooling and micro-alloyed steel, which is applied in the field of continuous casting, can solve the problems of difficult realization of continuous casting machines, reduce crack sensitivity, reduce the probability of transverse cracks at the corners of billets, and reduce stress concentration. Effect

Active Publication Date: 2016-07-06
BEIJING SHOUGANG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method requires the vertical section of the casting machine to be long enough to ensure the completion of the γ→α→γ transformation, which is difficult for domestic continuous casting machines

Method used

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  • Secondary Cooling Method for Controlling Transverse Cracks in Corner of Microalloyed Steel Slabs

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0019] Such as figure 1 as shown, figure 1 It is a schematic flowchart of a secondary cooling method for controlling transverse cracks at corners of microalloyed steel slabs provided by Embodiment 1 of the present invention.

[0020] Step S100: Control the temperature of the corner of the slab through the weak cooling mode after the slab crystallizes and before it leaves the bending section, so that the temperature of the corner of the slab is not lower than the Ae3 temperature, that is, in the equilibrium state, the austenite The highest temperature that coexists with ferrite. In this embodiment, temperature control is performed on the corners of the slab after crystallization and before leaving the bending section, so that the temperature of the corners of the slab can be obtained at a lower cooling rate under the action of the weak cooling mode. Precipitates with larger size and more diffuse distribution. Among them, the Ae3 temperature needs to be obtained according to ...

Embodiment approach 2

[0028]When a steel factory was casting a 230mm slab, severe corner transverse cracks occurred on both the inner and outer arcs of the slab. The steel type used was Q345X, the cross-sectional size was 1500mm×230mm, and the casting speed was 1.3m / min. The scheme of the present invention is used to reset the secondary cooling model, and the secondary cooling model is set as follows: during the time period after the slab is crystallized and before it leaves the bending section, the specific water volume is set to 0.28L / kg until the slab is cooled The highest temperature at which austenite and ferrite coexist in an equilibrium state. It can be understood that the highest temperature at which austenite and ferrite coexist needs to be tested to obtain an accurate value for the steel used in the steel plant. And then increase the specific water amount to 1.2L / kg during the period of time reaching the end of the straightening section until the slab cools down to the temperature at whic...

Embodiment approach 3

[0031] When a steel factory was casting a 230mm slab, severe corner transverse cracks occurred on both the inner and outer arcs of the slab. The steel used was Q345R-1, the cross-sectional size was 2050mm×230mm, and the casting speed was 1.0m / min. The scheme of the present invention is used to reset the secondary cooling model, and the secondary cooling model is set as follows: during the time period after the slab is crystallized and before it leaves the bending section, the specific water volume is set to 0.24L / kg until the slab is cooled The highest temperature at which austenite and ferrite coexist in an equilibrium state. It can be understood that the highest temperature at which austenite and ferrite coexist needs to be tested to obtain an accurate value for the steel used in the steel plant. And then increase the specific water amount to 0.8L / kg during the period of time reaching the end of the straightening section, until the slab is cooled to the temperature at which ...

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Abstract

The invention belongs to the technical field of continuous casting, and particularly relates to a secondary cooling method for controlling the transverse cracks at the corners of microalloy steel slabs. Control so that the temperature at the corner of the slab is not lower than the Ae3 temperature. In the equilibrium state, the highest temperature at which austenite and ferrite coexist; before entering the straightening section, the weak cooling mode is changed to the strong cooling mode, so that The corner temperature of the slab reaches the Ar3 temperature, that is, the temperature at which austenite begins to transform into ferrite during the cooling process of the slab; after entering the straightening section, the strong cooling mode is continued. By optimizing the control of the secondary cooling mode of the continuous casting slab, the present invention first obtains precipitates with larger size and more dispersed distribution through the weak cooling mode, which greatly enhances the plasticity of the slab, and then obtains a large proportion of intragranular iron through the strong cooling mode The plain body reduces stress concentration, thereby greatly reducing the probability of transverse cracks at the corners of the slab, which is simple and easy to implement.

Description

technical field [0001] The invention belongs to the technical field of continuous casting, in particular to a secondary cooling method for controlling transverse cracks at corners of microalloy steel slabs. Background technique [0002] By adding a certain amount of microalloying elements (such as vanadium, titanium, niobium, etc.) into the steel according to a specific process flow, a microalloyed steel with special properties can be formed. Carbonitrides combined with these microalloying elements can regulate the recrystallization process of deformed austenite and prevent grain growth, indirectly play a role in refining grains, and can also produce precipitation strengthening for the matrix, ultimately improving the steel's strength. Strength and toughness. If the process of combining microalloys with steel is not well controlled, a large number of carbonitrides combined with AlN, Nb, Ti and V will precipitate at the grain boundaries, which will reduce the plasticity of t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22D11/22
Inventor 李树森杨小刚张立峰张丽丽马威李中华倪有金张颖华
Owner BEIJING SHOUGANG CO LTD
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