Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Patent
1995-07-07
1997-08-05
Sheehan, John
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
148113, H01F 104
Patent
active
056538219
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an oriented electrical steel sheet for use as steel cores in transformers, electric motors, electric generators and other electric and electronic apparatuses. Particularly, the present invention relates to an oriented electrical steel sheet in which a steel slab composed of a particular composition is heated at a temperature lower than the conventional level, then a hot rolling is carried out, and then, a stabilization stage is undergone through a secondary recrystallization, whereby the oriented electrical steel sheet is made to have superior magnetic properties.
BACKGROUND OF THE INVENTION
The oriented electrical steel sheet has a texture in which the crystal grains have (110)[001] orientations. This product has extremely superior magnetic properties in the rolling direction, and by utilizing these properties, the product is used in transformers, electric motors, electric generators and other electric and electronic apparatuses as steel cores. This (110)[001] texture is obtained through a secondary recrystallization, and the secondary recrystallization grains are formed in such a manner that particularly oriented nuclei, i.e., nuclei having a (110)[001] orientation among the fine primary recrystallization grains are abnormally grown throughout the entire test piece. If such a secondary recrystallization having the particular orientation are to be promoted, the growth of the primary recrystallization grains has to be inhibited, and, for this purpose, precipitates of MnS, AlN and BN are used.
The oriented electrical steel sheet can be classified into two kinds based on the magnetic properties. The first is the conventional oriented electrical steel sheet which was almost perfected in 1960's, since Armco Company of the United States began industrial production from the early 1940's. This oriented electrical steel sheet shows a deviation of about 7.degree. of the orientation [001] relative to the rolling direction, while its magnetic flux density is about 1.80-1.86 Tesla at B10. The second kind is that which was developed by NSC company of Japan in 1970's, and this oriented electrical steel sheet shows a far more superior magnetic properties than the first kind. That is, the magnetic flux density is over 1.89 Tesla at B10, and the orientation [001] shows a deviation of only 3.degree..
Generally, the oriented electrical steel sheet is manufactured in the following manner. Generally, the steel slab contains 2-4% of silicon, and also contains grain growth inhibitors such as MnS, MnSe, and AlN. Then the steel slab undergoes complicated process steps: reheating and hot rolling - preliminary annealing first cold rolling - intermediate annealing - second cold rolling - decarburization annealing - coating of an annealing separator -final finish annealing - tension coating treatment. This is a first method, and a second method is carried out in the following manner. That is, first a preliminary annealing is carried out, then one-stage of strong rolling is carried out to the final thickness, and then, a decarburization annealing is carried out.
In the complicated manufacturing process for the oriented electrical steel sheet, the most difficult process step is the reheating step in which the steel slab is subjected to a high temperature heat treatment. In carrying out this steel slab reheating step, the precipitates of MnS or AlN are made to be finely precipitated after solid-solution spreading. In order to achieve this, it is unavoidable that the slab has to be heated to as high as 1400.degree. C., and has to be maintained at this temperature for 5 hours. Under this condition, the slab surface is reacted with the air, and consequently, there is formed an oxide called faylite (2FeO.multidot.SiO.sub.2) which is a composite material composed of Si oxides and Fe oxides. This oxide has a melting point as low as 1300.degree. C., and therefore, its melt flows down along the surface of the slab. This oxide melt is designed to flow down to the outside, but a part of i
REFERENCES:
patent: 4623407 (1986-11-01), Suga et al.
patent: 4692193 (1987-09-01), Yoshitomi et al.
patent: 5507883 (1996-04-01), Tanaka et al.
patent: 5512110 (1996-04-01), Yoshitomi et al.
Choi Gyu Seung
Hong Byung Deug
Lee Chung San
Woo Jong Soo
Pohang Iron & Steel Co. Ltd.
Research Institute of Industrial Science & Technology
Sheehan John
LandOfFree
Method for manufacturing oriented electrical steel sheet by heat does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing oriented electrical steel sheet by heat, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing oriented electrical steel sheet by heat will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1071950