Title:
PROCESS FOR PRODUCING GRAIN-ORIENTED MAGNETIC STEEL SHEET WITH EXCELLENT MAGNETIC PROPERTY
Document Type and Number:
WIPO Patent Application WO/2007/102282
Kind Code:
A1
Abstract:
A process for producing a complete-solid-solution nitride type grain-oriented
magnetic steel sheet which has a high magnetic flux density, satisfactory glass
coatability, and excellent magnetic properties. The process comprises: hot-rolling
a steel slab containing 2.5-4.0% silicon and containing acid-soluble aluminum
to obtain a hot-rolled steel strip in which the proportion of nitrogen separated
out as AlN to the nitrogen contained in the strip is 20% or lower; annealing and
cold-rolling the hot-rolled sheet; subsequently subjecting it to decarburization
annealing in an atmosphere in which PH2O/PH2 in the front
half is 0.30-0.70 and that in the back half is 0.20 or less to thereby regulate primary
recrystallized grains so as to have an average equivalent-circle diameter of
7-18 µm; subsequently nitriding the strip in a running state in a gas mixture
comprising hydrogen, nitrogen, and ammonia; thereafter regulating the oxygen
in the steel sheet before secondary recrystallization annealing to 450-700
ppm in terms of oxygen amount per 0.30 mm-thick sheet (So); subsequently applying
an annealing release agent; and then conducting secondary recrystallization
annealing in a hydrogen atmosphere which contains 25-75% nitrogen and in which
the temperatures at the hottest points on the periphery of a coil range from room
temperature to 950°C and the PH2O/PH2 is 0.01-0.15.
Inventors:
KUMANO TOMOJI (JP)
YAMAZAKI SHYUICHI (JP)
TANAKA OSAMU (JP)
YAMAZAKI SHYUICHI (JP)
TANAKA OSAMU (JP)
Application Number:
PCT/JP2007/050744
Publication Date:
September 13, 2007
Filing Date:
January 12, 2007
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
NITTETSU PLANT DESIGNING CORP (JP)
KUMANO TOMOJI (JP)
YAMAZAKI SHYUICHI (JP)
TANAKA OSAMU (JP)
NITTETSU PLANT DESIGNING CORP (JP)
KUMANO TOMOJI (JP)
YAMAZAKI SHYUICHI (JP)
TANAKA OSAMU (JP)
International Classes:
C21D8/12; B21B3/02; C21D9/46; C22C38/00; C22C38/60; C23C8/26; H01F1/16; H01F41/02
Foreign References:
| JP2005226111A | 2005-08-25 | |||
| JP2003166019A | 2003-06-13 | |||
| JP2003342642A | 2003-12-03 | |||
| JPH11279642A | 1999-10-12 | |||
| JPH11256242A | 1999-09-21 |
Other References:
See also references of EP 1992708A4
Attorney, Agent or Firm:
AOKI, Atsushi et al. (Toranomon 37 Mori Bldg. 5-1, Toranomon 3-chom, Minato-ku Tokyo 23, JP)
Download PDF: