HIGH-MAGNETIC-INDUCTION LOW-IRON-LOSS NON-ORIENTED SILICON STEEL SHEET AND MANUFACTURING METHOD THERFOR

Abstract

A high-magnetic-induction low-iron-loss non-oriented silicon steel sheet and a manufacturing method therefor. The chemical composition by mass percentages is: C≤0.005%, Si: 0.1%˜1.6%, Mn: 0.1%˜0.5%, P≤0.2%, S≤0.004%, Al≤0.003%, N≤0.005%, Nb≤0.004%, V≤0.004% and Ti≤0.003%, with the balance being Fe and inevitable impurities; and at the same time satisfies: 120≤[Mn]/[S]≤160, and [Nb]/93+[V]/51+[Ti]/48+[Al]/27≤[C]/12+[N]/14. After casting, the cooling rate in a cool-down process of casting slab is controlled, and a temperature controlling method is used to adjust the charging temperature of casting slab.

Claims

1. A manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet, comprising the following steps: creating a high-magnetic-induction low-iron-loss non-oriented silicon steel sheet comprising the following chemical composition by mass percentages: C≤0.005%, Si: 0.1%˜1.6%, Mn: 0.1%˜0.5%, P≤0.2%, S≤0.004%, Al≤0.003%, N≤0.005%, Nb≤0.004%, V≤0.004% and Ti≤0.003%, with the balance being Fe and inevitable impurities; and the above elements satisfy the following relationship at the same time: 120≤[Mn]/[S]≤160, and [Nb]/93+[V]/51+[Ti]/48+[Al]/27≤[C]/12+[N]/14; conducting processes of smelting, refining and continuous casting based on the chemical composition to form a casting slab, wherein in the continuous casting process, cooling rate during cooling process in which surface temperature of the casting slab is reduced from 1100° C. to 700° C. is controlled to 2.5° C./min to 20° C./min; heating the casting slab in a heating furnace, wherein charging temperature of the casting slab is controlled to 600° C. or less; hot rolling; pickling; cold rolling; final annealing; and coating.

2. The manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet according to claim 1, wherein the charging temperature of the casting slab is 300° C. or less.

3. The manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet according to claim 2, wherein the obtained non-oriented silicon steel sheet has the following electromagnetic properties: when Si content is 0.1%≤Si≤0.30%, the obtained non-oriented silicon steel sheet has magnetic induction B.sub.50≥1.76 T, iron loss P15/50≤7.00 W/kg; when Si content is 0.3%<Si≤0.80%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.75 T, iron loss P15/50≤6.00 W/kg; when Si content is 0.8%<Si≤1.20%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.72 T, iron loss P15/50≤4.00 W/kg; when Si content is 1.2%<Si≤1.60%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.70 T, iron loss P15/50≤4.00 W/kg.

4. The manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet according to claim 2, wherein the chemical composition of [Mn]/[S] is 120≤[Mn]/[S]≤140.

5. The manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet according to claim 1, wherein the obtained non-oriented silicon steel sheet has the following electromagnetic properties: when Si content is 0.1%≤Si≤0.30%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.76 T, iron loss P15/50≤7.00 W/kg; when Si content is 0.3%<Si≤0.80%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.75 T, iron loss P15/50≤6.00 W/kg; when Si content is 0.8%<Si≤1.20%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.72 T, iron loss P15/50≤4.00 W/kg; when Si content is 1.2%<Si≤1.60%, the obtained non-oriented silicon steel sheet has magnetic induction B50≥1.70 T, iron loss P15/50≤4.00 W/kg.

6. The manufacturing method for the high-magnetic-induction low-iron-loss non-oriented silicon steel sheet according to claim 1, wherein the chemical composition of [Mn]/[S] is 120≤[Mn]/[S]≤140.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 shows the relationship between [Mn]/[S] and magnetic induction B.sub.50 of the present invention.

[0048] FIG. 2 shows the relationship between the charging temperature of the casting slab and the magnetic induction B.sub.50 of the present invention.

[0049] FIG. 3 is a graph showing the type and size of precipitates when the cooling rate during the cooling process in which the surface temperature of the casting slab is reduced from 1100° C. to 700° C. is controlled to 2.5° C./min.

[0050] FIG. 4 is a graph showing the type and size of precipitates when the cooling rate during the cooling process in which the surface temperature of the casting slab is reduced from 1100° C. to 700° C. is controlled to 25° C./min.

DETAILED DESCRIPTION

[0051] The invention will be further illustrated by the following Examples.

[0052] Table 1 shows compositions of silicon steel sheets of Examples and Comparative Examples of the present invention. Table 2 shows the process design and electromagnetic properties of Examples and Comparative Examples of the present invention.

EXAMPLES

[0053] liquid iron and steel scrap are proportioned according to the chemical composition ratios in Table 1. After smelting in a 300-ton converter, decarburization, deoxidation and alloying are carried out by RH refining; the Mn content is dynamically adjusted according to the S content in the steel to obtain the optimum ratio of [Mn]/[S], and the C, N, Nb, V, Ti, and Al contents are controlled to meet the design requirements; after the liquid steel is cast by continuous casting, a casting slab of 170 mm to 250 mm thick and 800 mm to 1400 mm wide is obtained; after the casting, the cooling rate during the cooling process in which the surface temperature of the casting slab is reduced from 1100° C. to 700° C. is controlled to 2.5˜20° C./min; then, the charging temperature of the casting slab is adjusted to 600° C. or less, preferably 300° C. or less by a temperature controlling method; then, the casting slab is sequentially subjected to hot rolling, pickling, cold rolling, annealing and coating to obtain a final product. The process parameters and electromagnetic properties are shown in Table 2.

[0054] The explanation of the data in Table 1 and Table 2 is as follows:

[0055] In Table 1, the Si content is in the range of 0.1% to 1.6%. The steel can be divided into four types according to Si contents: a Si content of 0.11% to 0.30%, a Si content of 0.30% to 0.80% (does not comprise 0.30%), a Si content of 0.80% to 1.20% (does not comprise 0.80%), a Si content of 1.20% to 1.60% (does not comprise 1.20%), marked as A-grade, B-grade, C-grade, and D-grade respectively. Steels of the same grade having different Si content will have magnetic properties of the same type.

[0056] In the present invention, all A-grade steels (Examples 1-3) satisfy electromagnetic properties of a magnetic induction B.sub.50≥1.76 T and an iron loss P.sub.15/50≤6.50 W/kg; all B-grade steels (Examples 4-6) satisfy electromagnetic properties of a magnetic induction B.sub.50≥1.75 T and an iron loss P.sub.15/50≤5.40 W/kg; all C-grade steels (Examples 7-9) satisfy electromagnetic properties of a magnetic induction B.sub.50≥1.72 T and an iron loss P.sub.15/50≤4.00 W/kg; all D-grade steels (Examples 10-11) satisfy the electromagnetic properties of a magnetic induction B.sub.50≥1.70 T and an iron loss P.sub.15/50≤3.80 W/kg.

[0057] In Comparative Example 1, [Mn]/[S] is lower than the control requirement of 120. In Comparative Example 2, ([C]/12+[N]/14)−([Nb]/93+[V]/51+[Ti]/48+[Al]/27) is less than 0. In Comparative Example 3, neither [Mn]/[S] nor ([C]/12+[N]/14)−([Nb]/93+[V]/51+[Ti]/48+[Al]/27) satisfies the control requirements. In Comparative Example 4, the charging temperature of the slab is more than 600° C. In Comparative Example 5, the cooling rate of the casting slab is more than 20° C./min. In Comparative Example 6, [Mn]/[S], ([C]/12+[N]/14)−([Nb]/93+[V]/51+[Ti]/48+[Al]/27) and charging temperature of the casting slab does not satisfy the control requirements. In Comparative Example 7, the cooling rate of the casting slab is less than 2.5° C./min and the charging temperature of the casting slab is more than 600° C. In other words, as long as one condition does not satisfy the design requirements of the present invention, the electromagnetic properties of the corresponding steel are not good.

[0058] It can be seen that for the same grade, the non-oriented silicon steel sheet of the present invention has a higher magnetic induction and a lower iron loss.