Non-oriented silicon steel and manufacturing process thereof

Patent metadata

Field	Value
Publication number	US-10176910-B2
Application number	US-201214371028-A
Country	US
Kind code	B2
Filing date	Dec 11, 2012
Priority date	Mar 2, 2012
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

The present invention provides a non-oriented silicon steel with excellent magnetic properties and a manufacturing process therefor. During the manufacturing process of the present invention, the temperature T of the molten steel of steel tapped from a converter during steelmaking and the carbon content [C] and the free oxygen content [O] comply with the following formula: 7.27×103≤[O][C]e(−5000/T)≤2.99×104, and the final annealing step uses tension annealing at a low temperature for a short time. A non-oriented silicon steel with a low iron loss, and excellent anisotropy of iron loss can be obtained by means of the manufacturing process of the present invention.

First claim

What is claimed is:

1. A method for producing non-oriented silicon steel, the method comprising the following steps in sequence: a) steel making, b) hot rolling, c) normalizing, d) cold rolling, and e) annealing, wherein,
a casting slab containing the following composition by weight percentage is obtained by said steel making step a): C 0.001˜0.004%, Si 2.5˜4.0%, Al 0.5˜1.5%, Mn 0.10˜1.50%, P≤0.02%, S≤0.002%, N≤0.003%, B≤0.005%, where Mn/S≥300, Al/N≥300, and the balance being Fe and unavoidable impurities, wherein,
said steel making step a) includes converter steel making, in which the temperature T of molten steel during tapping on converter, the carbon content [C] and the free oxygen content [O] satisfy the following formula:
7.27×10 3 ≤[O][C] e (−5,000/T) ≤2.99×10 4 ,

wherein said steel making step a) further includes a step of RH refining, and in said RH refining, a deoxidation is implemented at the end of decarbonization first by using FeSi alloy and then by using FeAl alloy, in sequence;
in said annealing step e), the cold-rolled steel strip is heated to 900˜1,050° C., and then is subject to thermal insulation under a tension of 0.5˜1.5 MPa for a period of time t of 8˜60 sec;
wherein said casting slab contains Sn and Sb, the content of Sb+2Sn ranging between 0.001˜0.05 wt %; and
wherein further, the non-oriented silicon steel so produced comprises a grain diameter between 100 and 200 μm, a grain equivalent axial coefficient L between 1.05 and 1.35, an iron loss P15/50≤2.40 W/kg, and an anisotropy of iron loss ≤10%.

2. The method for producing non-oriented silicon steel according to claim 1 , wherein in said annealing step e), the temperature is 920˜1,000° C. and the tension is 1˜1.3 MPa.

3. The method for producing non-oriented silicon steel according to claim 1 , wherein the casting slab obtained in said steel making step a) satisfies: 350≤(Mn/S)≤600, 350≤(Al/N)≤600.

4. The method for producing non-oriented silicon steel according to claim 1 , wherein said cold rolling step d) has a reduction rate of 70˜88%.

5. The method for producing non-oriented silicon steel according to claim 1 , wherein a batch furnace of normalization is used in said normalizing step c) where the steel strip is subject to a thermal insulation at 780˜880° C. for 2˜6 hours under a protection atmosphere of nitrogen and hydrogen.

6. The method for producing non-oriented silicon steel according to claim 1 , wherein a continuous annealing of normalization is used in said normalizing step c) where the hot-rolled steel strip is firstly heated to 850˜950° C. at a heating rate of 5˜15° C./sec, and is subject to a thermal insulation under a protection atmosphere of nitrogen for a period of time t of 10˜90 sec, then is cooled to 650° C. at a cooling rate of 10° C./sec or less, and is finally left for natural cooling.

7. The method for producing non-oriented silicon steel according to claim 6 , wherein, in said normalizing step c), the hot-rolled steel strip is heated to 850˜930° C.

8. The method for producing non-oriented silicon steel according to claim 1 , wherein said hot rolling step b) has a deformation of 80% or more at 950° C. or more.

9. The method for producing non-oriented silicon steel according to claim 8 , wherein in said hot rolling step b), the maximum temperature difference between various positions of the hot-rolled steel strip is 20° C. or less.

Assignees

• Baoshan Iron & Steel

Inventors

• Xie Shishu
• Liu Xiandong
• Chen Xiao
• Hei Hongxu
• Wang Bo
• Ma Aihua
• Zou Liang
• Zhang Huawei
• Cao Wei
• Zhang Feng
• Liu Junliang

Classifications

• H01F1/14791

  Fe-Si-Al based alloys, e.g. Sendust · CPC title

• C22C38/04

  containing manganese · CPC title

• C21D8/1272

  Final recrystallisation annealing · CPC title

• C22C38/008

  containing tin · CPC title

• C21D9/46

  for sheet metals · CPC title