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Method of continuous annealing for steel strip with curie point and continuous annealing apparatus therefor

A technology of annealing equipment and Curie point, applied in the field of continuous annealing equipment, can solve the problems of poor strip dispersion, poor uniformity of decarburization, lack of disclosure and teaching, etc., and achieve the effect of high quality

Active Publication Date: 2010-02-17
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] However, in the above-mentioned document 1, there is no description about the change of the heating property of the steel strip itself along the longitudinal direction of the steel strip. From this, it can be seen that the invention described in the above-mentioned document 1 cannot avoid the following problem, that is, it is caused by the actual steel strip. The problem of non-uniformity in longitudinal heating properties such as longitudinal fluctuations in the temperature history during hot rolling; the resulting dispersion of various properties of the steel strip in the longitudinal direction
[0011] For example, the problem of poor uniformity of decarburization in the longitudinal direction of grain-oriented electrical steel sheets, the problem of film defects, or the problem of poor uniformity of mechanical strength in the longitudinal direction of ferritic stainless steel sheets and martensitic stainless steel sheets, Patent Document 1 The recorded invention does not solve the
[0012] In addition, the invention described in the above-mentioned document 2 aims at smoothly changing the annealing conditions from the preceding material to the succeeding material having different annealing conditions, and there is no description on uniform heating in the longitudinal direction of the steel strip.
[0013] In addition, the invention described in the above-mentioned document 3 discloses that the iron loss of the electrical steel sheet can be improved by applying rapid heating by electromagnetic induction heating to the Curie point of the decarburization annealing of the electrical steel sheet. Longitudinal temperature uniformity without any disclosure
[0014] In addition, the invention described in the above-mentioned document 4 discloses that the temperature uniformity in the steel plate can be improved by performing heat treatment so that the heating target temperature of the induction heating device is the magnetic transition temperature (Curie point) of the steel material or 700 to 760°C. However, whether the continuous annealing applied to the steel strip at an annealing temperature exceeding the Curie point can improve the temperature uniformity in the steel plate is not disclosed and taught

Method used

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  • Method of continuous annealing for steel strip with curie point and continuous annealing apparatus therefor
  • Method of continuous annealing for steel strip with curie point and continuous annealing apparatus therefor
  • Method of continuous annealing for steel strip with curie point and continuous annealing apparatus therefor

Examples

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Effect test

Embodiment 1

[0113] A steel plate containing C: 0.06%, Si: 3.3%, Mn: 0.1%, P: 0.03%, S: 0.008%, acid-soluble Al: 0.028%, N: 0.008%, and Cr: 0.1% in mass % After the billet was heated at 1150°C, it was hot-rolled to a thickness of 2.3mm to form a steel strip coil, and then two-stage annealing was performed at annealing temperatures of 1120°C and 920°C. And then, after cold rolling to plate thickness 0.22mm with reversing rolling mill, adopt the decarburization annealing equipment of prior art ( figure 1 , figure 2 ) and decarburization annealing equipment of the present invention ( figure 1 , Figure 4 ) for decarburization annealing. Thereafter, after high-temperature annealing, smoothing annealing is finally performed. At this time, the temperature of the steel sheet on the exit side of the heating zone of the furnace part 12 was measured by the sheet thermometer 38, and at the same time, the film defect rate of the grain-oriented electrical steel sheet after smoothing annealing was ...

Embodiment 2

[0119] A slab containing C: 0.005%, Si: 0.1%, Mn: 0.1%, Cr: 15%, P: 0.02%, S: 0.01%, and N: 0.01% in mass % is placed at a temperature of 1200°C After heating, it was hot-rolled to a plate thickness of 5 mm to form a coil, and then annealed at 900° C. was given. And then, after cold rolling to plate thickness 2mm with reversing rolling mill, utilize the mode of prior art in annealing equipment ( Figure 6 , Figure 7 ) and the mode of the present invention ( Figure 6 , Figure 8 ), bright annealed at 950°C. At this time, the hardness of the obtained ferritic stainless steel plate after bright annealing was measured, and the defect rate of strength was measured while measuring the temperature of the steel plate on the exit side of the heating zone of the furnace portion 12 with the plate thermometer 58 . The test conditions and results are shown in Table 2 (target values ​​A and B are the same as in Table 1).

[0120] In Examples 21 and 22 of the present invention, there ...

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Abstract

In the continuous annealing of a steel strip with Curie point (Tc) at an annealing temperature exceeding Tc with the use of a continuous annealing equipment composed of a heating area, a soaking areaand a cooling area, the heating treatment in the heating area is divided into three regions. In the first heating area, the steel strip is heated to below Tc-50 DEG C by radiant heating means by gas heating and / or radiant heating means by an electric heater. In the subsequent second heating area, the heated steel strip is heated to the region of Tc-30 DEG C to Tc-5 DEG C by solenoid coil high-frequency induction heating means. In the final third heating area, the heated steel strip is heated to a treatment target temperature exceeding Tc by radiant heating means by gas heating and / or radiant heating means by an electric heater. Accordingly, there can be attained uniform annealing in the longitudinal direction of the steel strip with Curie point.

Description

technical field [0001] The present invention relates to a continuous annealing method and a continuous annealing apparatus for a steel strip having a Curie temperature (Curie Temperature; also denoted as Tc.). In particular, it relates to a continuous annealing method and continuous annealing equipment for a steel strip having a Curie point which can be uniformly annealed in the longitudinal direction of the steel strip at an annealing temperature exceeding the Curie point. [0002] In addition, the continuous annealing method and the continuous annealing equipment of the present invention process the steel strip having the Curie point as the target, for example, grain-oriented electrical steel sheets (grain-oriented electrical steel sheets) containing 4.5% by mass or less of Si, and grain-oriented electrical steel sheets containing 18% by mass or less of Si. Cr ferritic stainless steel plate, martensitic stainless steel plate, etc. Background technique [0003] In continuo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/56C21D8/12C21D9/46C21D9/60
CPCC21D9/46F27B9/28F27B9/36C21D9/60C21D9/56C21D8/12Y02P10/25
Inventor 古贺重信片冈毅晴滨谷刚持永大照安宅诚
Owner NIPPON STEEL CORP
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