Non-oriented magnetic steel sheet and method for production thereof

A non-oriented electrical steel sheet comprising:

• on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 5% or less (including 0%);
• and
• Cu:
• 0.2% to 4%,
• wherein a volume ratio of Cu precipitates in crystal grain interior is in the range of from 0.2% to 2%, and
• an average particle size of the Cu precipitates is in the range of from 1 to 20 nm.

A non-oriented electrical steel sheet comprising:

• on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 5% or less (including 0%);
• and
• Cu:
• 0.2% to 4%,
• wherein the yield stress is not less than CYS (MPa) represented by the following formula 1,
• a volume ratio of Cu precipitates in crystal grain interior is in the range of from 0.2% to 2%, and
• an average particle size of the Cu precipitates is in the range of from 1 to 20 nm:
• note
• CYS=180+5,600[% C]+95[% Si]+50[% Mn]+37[% Al]+435[% P]+25[% Ni]+22d−1/2 (Formula 1)
• where d is an average grain diameter (mm) of the crystal grains.

A non-oriented electrical steel sheet comprising:

• on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 5% or less (including 0%);
• and
• Cu:
• 0.2% to 4%,
• Wherein, after aging treatment is performed at 500° C. for 10 hours, the yield stress of the steel sheet is not less than CYS (MPa) represented by the following formula 1:
• note
• CYS=180+5,600[% C]+95[% Si]+50[% Mn]+37[% Al]+435[% P]+25[% Ni]+22d−1/2 (Formula 1)
• where d is an average grain diameter (mm) of crystal grains.

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• less than 0.5% (including 0%);
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness,
• then performing finish annealing in which heating is performed to a Cu solid solution temperature+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from the Cu solid solution temperature to 400° C. is 10° C./s or more;
• and
• subsequently performing aging treatment at a temperature in the range of from 400 to 650° C.

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• less than 0.5% (including 0%);
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness,
• then performing finish annealing in which heating is performed to Ts represented by the following formula 2+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from Ts to 400° C. is 10° C./s or more;
• and
• subsequently performing aging treatment at a temperature in the range of from 400 to 650° C.:
• note
• Ts(° C.)=3,351/(3.279−log10[% C])−273 (Formula 2).

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 0.5% to 5%;
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness,
• then performing finish annealing in which heating is performed to a Cu solid solution temperature+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from the Cu solid solution temperature to 400° C. is 1° C./s or more;
• and
• subsequently performing aging treatment at a temperature in the range of from 400 to 650° C.

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 0.5% to 5%;
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness,
• then performing finish annealing in which heating is performed to Ts represented by the following formula 2+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from Ts to 400° C. is 1° C./s or more;
• and
• subsequently performing aging treatment at a temperature in the range of from 400 to 650° C.:
• note
• Ts(° C.)=3,351/(3.279−log10[% C])−273 (Formula 2).

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• less than 0.5% (including 0%);
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness, and
• then performing finish annealing in which heating is performed to a Cu solid solution temperature+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from the Cu solid solution temperature to 400° C. is 10° C./s or more.

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• less than 0.5% (including 0%);
• and
• Cu:
• 0.2% to 4%,
• Then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness, and
• then performing finish annealing in which heating is performed to Ts represented by the following formula 2+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from Ts to 400° C. is 10° C./s or more:
• note
• Ts(° C.)=3,351/(3.279−log10[% C])−273 (Formula 2).

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 0.5% to 5%;
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness, and
• then performing finish annealing in which heating is performed to a Cu solid solution temperature+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from the Cu solid solution temperature to 400° C. is 1° C./s or more.

A method for manufacturing a non-oriented electrical steel sheet, comprising the steps of:

• performing hot rolling of a steel slab containing on a mass percent basis,
• C:
• 0.02% or less (including 0%);
• Si:
• 4.5% or less;
• Mn:
• 3% or less;
• Al:
• 3% or less;
• P:
• 0.5% or less (including 0%);
• Ni:
• 0.5% to 5%;
• and
• Cu:
• 0.2% to 4%,
• then performing cold rolling or warm rolling to obtain a rolled steel sheet having a final sheet thickness, and
• then performing finish annealing in which heating is performed to Ts represented by the following formula 2+10° C. or more, followed by cooling in which a cooling rate in a temperature range of from Ts to 400° C. is 1° C./s or more:
• note
• Ts(° C.)=3,351/(3.279−log10[% C])−273 (Formula 2).