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Hot rolling method for silicon-ontaining steel slab

A billet and reheating technology, applied in the heating field of silicon-containing steel billets, can solve the problems of reduced surface quality of steel plates, impaired manufacturability, reduced magnetic properties, etc., and achieves the effect of reducing production failures, reducing surface defects and excellent surface quality.

Active Publication Date: 2014-12-10
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In the manufacturing process of the above-mentioned electrical steel sheet, especially in the manufacturing process such as cold rolling or continuous annealing, which is not a coil (coil) but a steel plate that is not coiled, due to the There is a problem that manufacturability is significantly impaired due to surface flaws where the steel sheet may be broken or other surface flaws may be generated due to this
In addition, although small surface flaws do not cause cracks in the steel sheet, they will become obvious by cold rolling, and uneven defects will be generated on the surface of the steel sheet, or the film thickness of the insulating coating will be uneven, or further, not only Decrease the surface quality of the finished steel sheet, and also cause a decrease in magnetic properties

Method used

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  • Hot rolling method for silicon-ontaining steel slab
  • Hot rolling method for silicon-ontaining steel slab
  • Hot rolling method for silicon-ontaining steel slab

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0067] For the content of C: 0.003% by mass, Si: 3.8% by mass, Mn: 0.05% by mass, sol.Al: 0.0040% by mass, N: 0.0030% by mass, S: 0.0015% by mass, and Se: 0.0015% by mass, the remainder contains Fe and For steel billets with unavoidable impurities, the heating rate from the billet reheating to 750°C is set to R 1 、The heating rate from 750℃ to 1050℃ is set as R 2 , For these R 1 And R 2 Various changes were made, and it was reheated to 1100°C, and then hot-rolled to produce a hot-rolled sheet with a thickness of 2.5 mm. The rate of occurrence of surface defects in the hot-rolled sheet was studied. It should be noted that for the occurrence rate of the above-mentioned surface flaws, the full length of the surface and back of the hot-rolled coil is observed with a CCD camera, and the occurrence of surface flaws is judged in a unit of 10cm×10cm, and it will be judged as the surface The area ratio of the surface of the steel sheet with defects is regarded as the occurrence rate of s...

Embodiment 2

[0070] use figure 1 The two billet reheating modes shown in Table 2 reheat the steel billets with various compositions shown in Table 2 to 1200°C and perform hot rolling to produce a hot-rolled plate with a thickness of 2.0 mm, as in Example 1. Measure the rate of occurrence of surface flaws in the hot-rolled sheet, and record the results in Table 2. The two billet reheating modes are: for the heating rate below 750°C, both in mode A and mode B 9.6°C / min; the temperature increase rate from 750°C to 1050°C is 5.7°C / min in mode A and 12.3°C / min in mode B.

[0071] According to Table 2, for steel billets of Nos. 22 to 25 outside the composition range of the present invention that are less likely to cause surface defects, regardless of the heating mode, the occurrence rate of surface defects shows a low value. In contrast, for steel billets (Nos. 1 to 21) having the composition of the present invention that are prone to surface defects, the occurrence rate of surface defects is high ...

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Abstract

When a steel slab, which has a component composition containing 0.03 mass% or less of C, 2.0-5.0 mass% of Si, 0.005-1.0 mass% of Mn, 0.040 mass% or less of sol. Al, 0.0005-0.0150 mass% of N and 0.030 mass% or less of S + Se with the balance made up of Fe and unavoidable impurities, is re-heated and hot rolled, the steel slab is re-heated so that heating rates R1 and R2 of the steel slab during the re-heating satisfy the following relation of 20 °C / min = R2 = R1 = 2 °C / min when the heating rate for the range from the beginning of the re-heating to 750°C is represented by R1 (°C / min) and the heating rate for the range from 750°C to 1,050°C is represented by R2 (°C / min) and then hot rolled, thereby reducing surface marks formed on the hot-rolled sheet.

Description

Technical field [0001] The present invention relates to a hot rolling method of silicon-containing steel billets used in materials such as electromagnetic steel sheets. Specifically, it relates to a method for heating silicon-containing steel billets, which is effective for preventing surface defects (defects) during hot rolling. Background technique [0002] Electrical steel sheets widely used as core materials for electronic equipment such as transformers and motors are roughly classified into grain-oriented electrical steel sheets and non-oriented electrical steel sheets. In these electrical steel sheets, for the purpose of reducing iron loss, a steel billet containing a maximum of about 5.0% by mass of silicon (Si) is used as a material for production. Furthermore, in the above-mentioned steel billet, in addition to Si, components such as C, Mn, Al, N, S, and Se are also added. These components are used as inhibitor components for secondary recrystallization, or for improving...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/12B21B1/02C22C38/00C22C38/60
CPCC22C38/04C21D9/46C22C38/02C21D6/008C21D8/12C21D8/1222C22C38/001
Inventor 高岛稔大谷刚日野善道藤田明男中西匡
Owner JFE STEEL CORP
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