Method for controlling internal defects of steel

A technology for internal defects and steel, applied in the field of steel rolling, can solve problems such as increased deformation, and achieve the effects of reducing rolling passes, reducing production costs, and improving production costs and operational control difficulties.

Inactive Publication Date: 2013-03-20
PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the above-mentioned existing technical defects, and the purpose is to provide a method for controlling the internal defects of steel. The degree of deformation of the part increases to ensure that internal defects can be welded to the greatest extent, so that the steel can meet the requirements of φ2 ultrasonic flaw detection and improve the pass rate of ultrasonic flaw detection

Method used

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  • Method for controlling internal defects of steel
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Examples

Experimental program
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Effect test

Embodiment 1

[0037] Adopt the following method to roll the 360×450mm continuous casting billet into 250×250mm axle steel: First, ensure sufficient soaking time during the heating process of the billet (here, the soaking time is determined according to the billet specification, in In this embodiment, a soaking time of ≥ 1.5 hours is adopted to make the temperature inside and outside the slab uniform; then, adjust the high-pressure water descaling parameters after being out of the furnace, so that the surface temperature of the slab is rapidly reduced, and the surface temperature of the slab is controlled. The temperature is lower by 100°C to 150°C; then, rolling is performed using the rolling process in Table 2 below.

[0038] In Example 1, the steps for adjusting the high-pressure water descaling parameters are as follows: increase the high-pressure water descaling equipment from 3.2m to 5m, use 12Mpa water pressure for the first 3m to ensure the descaling effect, and use 10Mpa water pressu...

Embodiment 2

[0046] Adopt the following method to roll the 360×450mm cast slab into 260×260mm square steel: first, ensure sufficient soaking time in the heating process of the cast slab (the soaking time is determined according to the cast slab specification, in this embodiment Adopted ≥ 1.5 hours of soaking time) to make the internal and external temperature of the slab uniform; then, adopt the same method as the method in embodiment 1 to adjust the high-pressure water descaling parameters after being out of the furnace, so that the surface temperature of the slab is rapidly reduced, and the control center The part is 100°C-150°C higher than the surface temperature; then, the rolling process in Table 3 is used for rolling. In Table 3, the reduction rate of the sixth pass is 25%, and the shape coefficient of the deformation zone is 0.64.

[0047] Table 3 Rolling process of 260×260mm square steel by the method of Example 2

[0048]

pass

Billet inlet specification

...

Embodiment 3

[0053] Adopt the following method to roll the slab of 360×450mm into square steel of 230×230mm: first, ensure sufficient soaking time in the heating process of the slab (the soaking time is determined according to the specification of the slab, in this embodiment Adopted ≥ 1.5 hours of soaking time) to make the internal and external temperature of the slab uniform; then, adopt the same method as the method in embodiment 1 to adjust the high-pressure water descaling parameters after being out of the furnace, so that the surface temperature of the slab is rapidly reduced, and the control center The part is 100°C-150°C higher than the surface temperature; then, the rolling process in Table 4 is used for rolling. In Table 4, the reduction rate of the sixth pass is 25.4%, and the shape coefficient of the deformation zone is 0.67; the reduction rate of the seventh pass is 25.0%, and the shape coefficient of the deformation zone is 0.66.

[0054] Table 4 Rolling process of 230×230mm ...

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Abstract

The invention provides a method for controlling internal defects of steel so that the steel can satisfy the requirement of ultrasonic flaw detection of the diameter of 2mm. The method controls temperature gradients inside and outside a casting blank by adjusting high-pressure water jet descaling parameters and then controls pass reduction so that deformation conditions in a rolled piece are changed, the core defects of the rolled piece are fully welded, and the internal defects of the casting blank are controlled within the diameter of 2mm to satisfy the requirement of the ultrasonic flaw detection of the diameter standard of 2mm. The method can improve the qualified rate of the ultrasonic flaw detection for steel, can reduce rolling passes, decreases the production cost and improves the production efficiency.

Description

technical field [0001] The invention belongs to the field of steel rolling, in particular to a method for controlling internal defects of steel. Background technique [0002] Generally, in order to meet the service life and operation safety of steel products, there are corresponding requirements for internal defects of steel, and ultrasonic flaw detection is a means of judging internal defects of steel. Therefore, some high-quality steel products are included in the corresponding standards. Ultrasonic flaw detection regulations, such as the TB / T2945-1999 standard for the technical conditions of LZ50 steel axles and billets for railway vehicles, the GJ8A-98 standard for carbon steel rods for shells, the GB3087-1999 standard for seamless steel pipes for low and medium pressure boilers, etc. . [0003] Ultrasonic flaw detection is a method of inspecting defects by using ultrasonic energy to penetrate deep into metal materials, and when one section enters another section, refle...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B21B1/46
Inventor 邓通武代华云柯晓涛邓勇杨星地刘明贾瑜陶功明
Owner PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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