Metal treatment – Process of modifying or maintaining internal physical... – Magnetic materials
Patent
1996-12-19
1998-09-08
Sheehan, John
Metal treatment
Process of modifying or maintaining internal physical...
Magnetic materials
148111, H01F 1147
Patent
active
058039899
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for producing a non-oriented electrical steel sheet, for use as iron core material for electrical machinery and apparatus, possessing excellent magnetic properties, i.e., a high magnetic flux density and a low iron loss.
BACKGROUND ART
In recent years, in the field of electrical machinery and apparatus, particularly rotary machines and medium and small size transformers where non-oriented electrical steel sheets are used as iron core materials, a trend toward saving electric power and energy and protecting the earth's environmental, such as the regulation of flon gas, has led to a rapid trend toward an increase in efficiency. For this reason, regarding non-oriented electrical steel sheets as well, there is an ever-increasing demand for improved properties, that is, high magnetic flux density and low iron loss.
In non-oriented electrical steel sheets, increasing the content of Si, Al or the like has been conducted as a method for lowering the iron loss from the viewpoint of reducing the eddy-current loss due to increased electric resistance. This method, however, has a problem that a lowering in magnetic flux density is unavoidable. Further, besides a mere increase in content of Si, Al or the like, lowering the contents of C, N, S, O or the like to increase the purity of the steel (Japanese Unexamined Patent Publication (Kokai) No. 61-231120) and improving the production process, such as a finish annealing cycle (Japanese Unexamined Patent Publication (Kokai) No. 57-35626) have been proposed. For all the above methods, although the iron loss could be lowered, no significant effect could be attained for the magnetic flux density. On the other hand, in order to improve the magnetic flux density by improving the texture of products, the regulation of the reduction ratio in cold rolling before finish annealing in a proper range to enrich ND//<110> orientation being effective for improving the magnetic flux density and having <100> orientation which is the axis of easy magnetization in the crystallographic axis, in the product sheet plane, within a primary recrystallized texture and, at the same time, to lower the integration of ND//<111>-based orientation having <111> orientation which is the direction of difficult magnetization in the crystallographic axis, in the product sheet plane, or the adoption of a hot rolled sheet annealing to coarsen the grain structure before cold rolling for the same purpose, or an increase in magnetic flux density by device of hot rolling conditions or the like have been attempted in the art. These methods, however, have not led to the production of non-oriented electrical steel sheets having a combination of high magnetic density with low iron loss and, hence, could not meet the demand for the non-oriented electrical steel sheets. In order to remove the above limit of the prior art, the present inventors have aimed at, and have made studies on, controlled hot rolling and conditions for self-annealing wherein annealing is performed by taking advantage of heat possessed by the coil after coiling of the hot rolled strip.
In the step of hot rolling a non-oriented electrical steel sheet having phase transformation, the grain diameter of the hot rolled sheet has been regulated to improve the magnetic properties of the product. Regarding the self-annealing of the hot-rolled sheet, Japanese Unexamined Patent Publication (Kokai) No. 54-76422 discloses a self-annealing technique, and the use of a heat-holding cover for ensuring the coil temperature during the self-annealing is specified in Japanese Unexamined Patent Publication (Kokai) No. 56-33436. Further, Japanese Unexamined Patent Publication (Kokai) Nos. 57-57829 and 60-50117 disclose a method wherein self-annealing conditions are properly set to coarsen the grain structure of the hot rolled sheet, thereby improving the magnetic property of the product, and Japanese Unexamined Patent Publication (Kokai) No. 58-136718 discloses a method wherein the fi
REFERENCES:
patent: 5421912 (1995-06-01), Kumano et al.
Kawamata Ryutaro
Kubota Takeshi
Kumano Tomoji
Nippon Steel Corporation
Sheehan John
LandOfFree
Process for producing non-oriented electrical steel sheet having does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing non-oriented electrical steel sheet having, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing non-oriented electrical steel sheet having will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1278227