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Hot rolling method for silicon-ontaining steel slab

A steel billet and reheating technology, which is applied in the heating field of silicon-containing steel billets, can solve the problems of steel plate surface quality reduction, manufacturability damage, magnetic property reduction, etc., and achieve the effects of reducing production failures, reducing surface defects, and excellent surface quality

Active Publication Date: 2013-08-07
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 containing C: 0.003 mass %, Si: 3.8 mass %, Mn: 0.05 mass %, sol.Al: 0.0040 mass %, N: 0.0030 mass %, S: 0.0015 mass % and Se: 0.0015 mass %, the rest contains Fe and For steel slabs with unavoidable impurities, the temperature rise rate from the start of reheating the slab to 750°C is R 1 , Let the temperature rise rate from 750°C to 1050°C be R 2 , for these R 1 and R 2 Various changes were performed, and then heated to 1100° C., followed by hot rolling to obtain a hot-rolled sheet having a thickness of 2.5 mm, and the rate of occurrence of surface flaws in the hot-rolled sheet was studied. It should be noted that, regarding the occurrence rate of the above-mentioned surface flaws, use a CCD camera to observe the entire length of the front and back of the hot-rolled coil, and judge whether there are surface flaws in units of 10cm×10cm, which will be judged as surface flaws. The area ratio of the flawed steel sheet surface was taken as the occurrence rate of sur...

Embodiment 2

[0070] use figure 1 In the two billet reheating modes shown, the steel billets having the various compositions shown in Table 2 were reheated to 1200°C and hot-rolled to produce hot-rolled sheets with a thickness of 2.0 mm, in the same manner as in Example 1. Measure the occurrence rate 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 rate of temperature increase from 750°C to 1050°C was 5.7°C / min in mode A and 12.3°C / min in mode B.

[0071] According to Table 2, for steel slabs Nos. 22 to 25 outside the composition range of the present invention, which are less likely to generate surface flaws, the occurrence rate of surface flaws shows a low value regardless of the heating mode. In contrast, for the steel billets (No.1-21) with the composition of the present invention that are prone to surface flaws, in the reheating mode A that does not...

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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 DEG C / min >= R2 >= R1 >= 2 DEG C / min when the heating rate for the range from the beginning of the re-heating to 750 DEG C is represented by R1 ( DEG C / min) and the heating rate for the range from 750 DEG C to 1,050 DEG C is represented by R2 ( DEG 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 for a silicon-containing steel billet used in materials such as electrical steel sheets, in particular to a heating method for a silicon-containing steel billet, which is effective for preventing surface flaws (defects) during hot rolling. Background technique [0002] Electrical steel sheets widely used as core materials for electronic devices such as transformers and motors are broadly classified into oriented electrical steel sheets and non-oriented electrical steel sheets. These electrical steel sheets are manufactured using a steel billet containing silicon (Si) at a maximum of about 5.0% by mass for the purpose of reducing iron loss. Further, in the above-mentioned steel billet, in addition to Si, components such as C, Mn, Al, N, S, Se, etc. are added, and these components are used as inhibitor components for secondary recrystallization, or to improve metal Added for various purposes such as ...

Claims

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Application Information

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IPC IPC(8): C21D8/12B21B1/02C22C38/00C22C38/60
CPCC22C38/04C21D9/46C22C38/02C21D6/008C21D8/12C22C38/001C21D8/1222
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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