Non-oriented electrical steel sheet, method for producing same, and hot-rolled steel sheet

Patent metadata

Field	Value
Publication number	US-2023366058-A1
Application number	US-202018033376-A
Country	US
Kind code	A1
Filing date	Nov 27, 2020
Priority date	Nov 27, 2020
Publication date	Nov 16, 2023
Grant date	—

Abstract

A non-oriented electrical steel sheet is provided which has a chemical composition that contains, in mass%, C: 0.0050% or less, Si: 0.10 to 1.50%, Mn: 0.10 to 1.50%, sol. Al: 0.0050% or less, N: 0.0030% or less, S: 0.0040% or less, and O: 0.0050 to 0.0200%, and contains one or more elements selected from a group of La, Ce, Zr, Mg and Ca in a total amount of 0.0005 to 0.0200%, with the balance being Fe and impurities. A number density N of suitable oxide particles is 3.0×10 3 to 10×10 3 particles/cm 2 , and a number density n of oxide particles containing La and the like satisfies the expression n/N≥0.01.

First claim

1 . A non-oriented electrical steel sheet having a chemical composition comprising, in mass %,
C: 0.0050% or less, Si: 0.10 to 1.50%, Mn: 0.10 to 1.50%, sol. Al: 0.0050% or less, N: 0.0030% or less, S: 0.0040% or less, O: 0.0050 to 0.0200%, Sn: 0.50% or less, and one or more of La, Ce, Zr, Mg and Ca: 0.0005 to 0.0200% in total, with the balance comprising Fe and impurities, wherein: a number density N of oxide particles containing, in mass %, O: 20 to 60% and Si: 20 to 60%, and having a diameter of 1.0 to 5.0 μm is 3.0×10 3 to 10×10 3 particles/cm 2 , and among the oxide particles, a number density n of oxide particles containing one or more of La, Ce, Zr, Mg and Ca in a total amount of 1.0% by mass or more satisfies Formula (i) below:
n/N≥ 0.01 . . .   (i).

2 . (canceled)

3 . The non-oriented electrical steel sheet according to claim 1 , wherein:
an average spacing between the oxide particles is 30 to 300 μm.

4 . The non-oriented electrical steel sheet according to claim 1 , wherein:
an average crystal grain size is 30 μm or less, and an average crystal grain size after performing stress relief annealing under conditions of holding the non-oriented electrical steel sheet at 750° C. for two hours is 50 μm or more.

5 . A method for producing the non-oriented electrical steel sheet according to claim 1 , comprising:
a refining process of producing molten steel, a continuous casting process of subjecting the molten steel to continuous casting to produce a slab having a chemical composition according to claim 1 , a hot rolling process of, after heating the slab that is obtained, performing hot rolling to obtain a hot-rolled steel sheet, a pickling process of performing pickling on the hot-rolled steel sheet, a cold rolling process of performing cold rolling on the hot-rolled steel sheet after pickling to obtain a cold-rolled steel sheet, and a finish annealing process of subjecting the cold-rolled steel sheet to finish annealing, wherein: in the refining process, an oxygen amount of the molten steel before alloy addition is made, in mass %, 0.010 to 0.050%, and next, an amount M1 of Si added to the molten steel and a content M2 of Si in the slab are adjusted so as to satisfy Formula (ii) below; and a nozzle is used in the continuous casting process, a part or all of an inner wall of the nozzle that comes in contact with the molten steel comprising a material that contains, in a total amount of 3 to 60% by mass %, oxides containing one or more of La, Ce, Zr, Mg and Ca;
0.90≤M2/M1≤1.10 . . .   (ii).

6 . The method for producing the non-oriented electrical steel sheet according to claim 5 , wherein:
in the refining process, a time period from when alloy addition ends until the continuous casting process is started is within a range of 30 to 180 minutes; and in the hot rolling process, after holding a temperature of the slab within a range of 1050° C. or more to less than 1150° C. for 15 to 240 minutes, hot rolling of the slab is immediately performed.

7 . The method for producing the non-oriented electrical steel sheet according to claim 5 , wherein:
in the finish annealing process, a temperature of the cold-rolled steel sheet is made 800° C. or more to less than 850° C.

8 . A hot-rolled steel sheet which serves as a starting material for the non-oriented electrical steel sheet according to claim 1 , having a chemical composition containing, in mass %,
C: 0.0050% or less, Si: 0.10 to 1.50%, Mn: 0.10 to 1.50%, sol. Al: 0.0050% or less, N: 0.0030% or less, S: 0.0040% or less, O: 0.0050 to 0.0200%, and Sn: 0.50% or less, and containing one or more of La, Ce, Zr, Mg and Ca in a total amount of 0.0005 to 0.0200%, with the balance comprising Fe and impurities, wherein: a number density N of oxide particles containing, in mass %, O of 20 to 60% and Si of 20 to 60%, and having a diameter of 1.0 to 5.0 μm is 3.0×10 3 to 10×10 3 particles/cm 2 , and among the oxide particles, a number density n of oxide particles containing one or more of La, Ce, Zr, Mg and Ca in a total amount of 1.0% by mass or more satisfies Formula (i) below:
n/N≥ 0.01 . . .   (i).

9 . (canceled)

10 . The hot-rolled steel sheet according to claim 8 , wherein:
an average spacing between the oxide particles is 30 to 300 μm.

Assignees

• Nippon Steel Corp

Inventors

• Arita Yoshihiro
• Matsui Shinichi

Classifications

• C21D9/46 Primary

  for sheet metals · CPC title

• C22C38/06

  containing aluminium · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/02 Primary

  containing silicon · CPC title

• C22C38/008

  containing tin · CPC title