High-strength electrical steel sheet and method of producing the same

Patent metadata

Field	Value
Publication number	US-10242782-B2
Application number	US-201214413658-A
Country	US
Kind code	B2
Filing date	Aug 8, 2012
Priority date	Aug 8, 2012
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

According to the present invention, a high-strength electrical steel sheet that is suitable as rotor material for a high speed motor, steadily has high strength, and also has excellent magnetic properties can be obtained by setting the chemical composition thereof to include, by mass %, C: 0.005% or less, Si: more than 3.5% and 4.5% or less, Mn: 0.01% or more and 0.10% or less, Al: 0.005% or less, Ca: 0.0010% or more and 0.0050% or less, S: 0.0030% or less, and N: 0.0030% or less, Ca/S being 0.80 or more, the balance being Fe and incidental impurities, and by setting the sheet thickness to 0.40 mm or less, the non-recrystallized deformed microstructure to 10% or more and 70% or less, tensile strength (TS) to 600 MPa or more, and iron loss W 10/400 to 30 W/kg or less.

First claim

The invention claimed is:

1. An electrical steel sheet, a chemical composition thereof comprising, by mass %, C: 0.005% or less, Si: more than 3.5% and 4.5% or less, Mn: 0.01% or more and 0.10% or less, Al: 0.005% or less, Ca: 0.0010% or more and 0.0050% or less, S: 0.0030% or less, and N: 0.0030% or less, Ca/S being 0.80 or more, the balance being Fe and incidental impurities, a sheet thickness being 0.40 mm or less, a non-recrystallized deformed microstructure being 10% or more and 70% or less, tensile strength (TS) being 600 MPa or more, and iron loss W 10/400 being 30 W/kg or less,
wherein a variation in tensile strength (TS) of the electrical sheet in a direction orthogonal to a rolling direction is 2σ≤15 MPa.

2. The electrical steel sheet according to claim 1 , the chemical composition thereof further comprising, by mass %, at least one selected from the group consisting of Sb: 0.005% or more and 0.2% or less, Sn: 0.005% or more and 0.2% or less, P: 0.01% or more and 0.2% or less, Mo: 0.005% or more and 0.10% or less, B: 0.0002% or more and 0.002% or less, and Cr: 0.05% or more and 0.5% or less.

3. A method of producing an electrical steel sheet comprising a series of processes including heating and then hot rolling a slab having the chemical composition according to claim 1 to obtain a hot-rolled sheet, subsequently coiling and subjecting the sheet to hot band annealing and pickling, then performing cold or warm rolling to yield a sheet thickness of 0.40 mm or less, and then subjecting the sheet to final annealing;
a temperature during the heating of the slab being 1050° C. or higher and 1150° C. or lower, a finisher delivery temperature in the hot rolling being 800° C. or higher and 900° C. or lower, a temperature for the coiling being 500° C. or higher and 650° C. or lower, a temperature for the hot band annealing being 900° C. or higher and 1000° C. or lower, and the final annealing being performed in an atmosphere containing 10 vol % or more of hydrogen and having a dew point of −20° C. or lower, and in a temperature range from over 650° C. to less than 800° C.

4. A method of producing an electrical steel sheet comprising a series of processes including heating and then hot rolling a slab having the chemical composition according to claim 2 to obtain a hot-rolled sheet, subsequently coiling and subjecting the sheet to hot band annealing and pickling, then performing cold or warm rolling to yield a sheet thickness of 0.40 mm or less, and then subjecting the sheet to final annealing;
a temperature during the heating of the slab being 1050° C. or higher and 1150° C. or lower, a finisher delivery temperature in the hot rolling being 800° C. or higher and 900° C. or lower, a temperature for the coiling being 500° C. or higher and 650° C. or lower, a temperature for the hot band annealing being 900° C. or higher and 1000° C. or lower, and the final annealing being performed in an atmosphere containing 10 vol % or more of hydrogen and having a dew point of −20° C. or lower, and in a temperature range from over 650° C. to less than 800° C.

Assignees

• Toda Hiroaki
• Nakanishi Tadashi
• Kohno Masaaki
• Oda Yoshihiko
• Jfe Steel Corp

Inventors

• Toda Hiroaki
• Nakanishi Tadashi
• Kohno Masaaki
• Oda Yoshihiko

Classifications

• C22C38/06

  containing aluminium · CPC title

• C22C38/22

  with molybdenum or tungsten · CPC title

• C22C38/02 Primary

  containing silicon · CPC title

• C22C38/008

  containing tin · CPC title

• C21D8/1272

  Final recrystallisation annealing · CPC title