JPH01227A - Manufacturing method of high tensile strength non-oriented electrical steel sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing a high tensile strength non-oriented electrical steel sheet, and a method for manufacturing a high strength magnetic material with low core loss for high-speed rotating machines and for electromagnetic switches. The present invention relates to a method of manufacturing a magnetic material suitable for excellent wear resistance.

(Prior Art) Conventionally, the rotational speed required for rotating equipment is about 100,000 rpm at most, and laminated electromagnetic steel plates have been used as the material for the rotor.

Recently, ultra-high speed rotation of 200,000 to 300,000 rpm has become necessary, and there is a possibility that the centrifugal force applied to the rotor may exceed the strength of the electromagnetic control plate.

For this reason, ultra-high-speed rotating machines usually use cast steel solid rotors with sufficient strength instead of electromagnetic steel sheets. However, in this case, the cost is high because it requires a complicated machining process to cut the rotor from a cast steel block.Furthermore, compared to the laminated type, eddy current loss is greater, resulting in a significant drop in motor efficiency. .

Furthermore, because the contact surface of an electromagnetic switch wears out as it is used, a magnetic material that has not only excellent magnetic properties but also excellent wear resistance is desired.

In response to such needs, non-oriented electrical steel sheets with high tensile strength have recently been studied, and several proposals have been made. High at 7.0%, and further Mn:
0.1-11.5%, Ni: 0.1-20.0%, Co
: 0.5-20.0%, Ti: 0.05-3.0%
, W: 0.05-3.0%, Mo: 0.05-3.0%
, Al: 0.5-13.0% A slab containing 1.0-20.0% of one or more solid solution strengthening components is used as a raw material, and after hot rolling, a hot-rolled plate with a hardness of 100-600% is used. ℃ repeated warm rolling to final plate thickness and annealing, tensile strength is 50k.
This is a method for producing a high tensile strength non-oriented electrical steel sheet with a tensile strength of 1.5 g/m" or more.

Since this has a high St content that is difficult to roll, tedious warm rolling is required, but there is a risk that plate breakage will occur more often during rolling, resulting in lower productivity and lower yields. There is room for

In JP-A No. 61-84360, Ni: 8 to 20%,
Mo: 0.2-5.0%, Al: 0.1-2.
0%, Ti: O, 1-1.0%, Cr: 1.
A high tensile strength soft magnetic material for high speed rotating electric motors containing 0 to 1 O, 0% has been proposed. This is an extremely expensive material, especially since it contains a large amount of Ni, as well as Mo and Cr.

Furthermore, Japanese Patent Application Laid-Open No. 61-9520 discloses that Si: 2.5 to 7.
．． 0%, Ti: 0.05~3.0%, W:Q, Q5~
3.0%, Mo: 0.05-3.0%, Ni: 0.
1 to 20.0%, p, tt: 0.5 to 13.0%, or molten steel containing 1.0 to 20.0% of 211 or more to produce high tensile strength non-oriented electrical steel sheet by rapid solidification method. It is intended to be manufactured. Because this process is special, it cannot be manufactured using normal electromagnetic steel sheet manufacturing equipment, and it is considered difficult to produce it industrially.

(Problems to be Solved by the Invention) As described above, there have been proposals for manufacturing non-oriented electrical steel sheets with high tensile strength, but it is difficult to manufacture them industrially stably using ordinary electrical steel sheet manufacturing equipment. The reality is that we have not yet reached that point.

Furthermore, as mentioned above, high tensile strength non-oriented electrical steel sheets are used as materials for ultra-high-speed rotating electric equipment and electromagnetic switches, so in addition to having high tensile strength, they also need to have low core loss and excellent magnetic flux density. .

The present invention has a yield strength YP≧55 kg/am” and a tensile strength TS suitable as a material for ultra-high-speed rotating machines and electromagnetic switches.
≧5 Q kg/m”, hardness HJJV≧150, high strength and wear resistance, and magnetic flux density B50≧1.6
High tensile strength non-oriented electrical steel sheets with excellent magnetic properties of 0T are used during rolling and other process lines.
The aim is to stably manufacture it on an industrial scale without causing plate breakage or the like.

(Means for Solving the Problems) The present inventors have conducted various experiments and studies in order to achieve the above object. That is, in the present invention, C: 0.01% or less, Si:
2.0% or more and 3.5% or less, Mn: 0.1% or more l01
0% or less, P: 0.20% or less, A1: 0.10% or more and 1.50% or less, s: o, oos% or less, and if necessary, contains 6.0% or less of Nl, with the balance being iron. When hot rolling a slab containing unavoidable impurities,
Coiling is performed at a temperature below the coiling temperature (CT; °C) shown by the following equation of the relationship with the hot-rolled sheet thickness (L; mms), and further after coiling,
Start cooling within 300°C at an average cooling rate of 100°C/hour or more, then leave it as is without annealing, or annealing the hot rolled sheet, cold rolling, annealing, This is a method for manufacturing non-oriented electrical steel sheets with high tensile strength and excellent magnetic properties.

CT (°C)≦-200xt (am)+1000 However, 0.5≦t≦2.5 First, the steel components will be described.

C is a component that deteriorates magnetic properties, and is 0.01 (heavy it)
If the content exceeds 0.01%, iron loss increases.
% or less. Note that C may be brought into the above range by decarburizing with a hot-rolled plate or a cold-rolled plate instead of decarburizing with steel manufacturing.

Si increases the specific resistance of steel, reduces eddy currents, lowers iron loss, and increases tensile strength, but the content is 2.
If it is less than 0%, the effect will be small, and if it exceeds 3.5%, it will make the steel brittle and further reduce the magnetic flux density of the product, so the content should be 3.5% or less.

Mn increases the tensile strength of steel, increases specific resistance, and reduces iron loss, but if it is less than 0.1%, the effect is small, and preferably from more than 1.0% to 5.0%.

If it exceeds 10.0%, the magnetic flux density of the finished product will decrease, so
It is set to 0.1 to 10.0%.

P is an element that has a remarkable effect of increasing tensile strength, but 0.2
If it exceeds 0%, embrittlement will be severe and processing such as hot rolling or cold rolling on an industrial scale will be difficult, so the upper limit is set to 0.20%.

In addition, when using the product with punched or sheared edges, if exposed to an atmosphere of 150°C or higher for a long time, Po
If it exceeds .03%, the apparent top elongation may deteriorate. This is thought to be due to the fact that the fractured surface of the high tensile strength steel plate is relatively likely to contain microcranks, strain aging, etc.

Therefore, if elongation after aging is a problem for the purpose of use, adopt a method for processing the end face to make it smooth and free from distortion.

■ Punching with sandpaper and removing the sheared surface layer are effective. Further, if the Po component is set to 0.03% or less, the above problem does not occur.

At least 0.10% of Al is required as a deoxidizer, and by including A6, the strength is improved.
Iron loss also decreases as the specific resistance increases, but if it exceeds 1.50%, embrittlement becomes a problem, so it is set to 0.IO to 1.50%.

B segregates at grain boundaries and has the effect of suppressing embrittlement due to grain boundary segregation of P, but if it exceeds 0.008%, it will become extremely brittle, so the upper limit is set at 0.008%.

Furthermore, Ni is contained if necessary. Ni has less negative effect on magnetic properties and is effective in improving tensile strength, but 6.0
If it exceeds 6.0%, the magnetic flux density will decrease significantly, so it is set to 6.0% or less.

A steel slab containing the above components and the remainder consisting of iron and unavoidable impurities is melted in a converter and continuously cast or ingot-formed.
Manufactured by blooming rolling.

The steel slab is heated in a known manner and then heated to a temperature of e.g.
Hot rolled to a thickness of ~3.5 mm. The relationship between the coiling temperature and the hot-rolled plate thickness during hot rolling and the cooling conditions after coiling are important for improving the rollability and workability of the steel plate. Winding is carried out at a temperature below the winding temperature corresponding to the thickness of the plate, and cooling is started within 5 hours after winding.
Cool to 00°C at an average cooling rate of 100°C/hour or more.

In hot rolling, the coiling temperature (CT) is determined by the hot rolled sheet thickness (tH
(fin)) and wind it up.

The reason for this is to prevent the fact that if the sheet is wound at a temperature exceeding the winding temperature (CT) corresponding to the sheet thickness (1) shown by this formula, it will become brittle and the sheet will frequently break during rolling.

If a long time passes after winding and the cooling rate is slow, the steel will become brittle, so to prevent this, it is necessary to start cooling within 5 hours after winding. The cooling rate must be an average cooling rate of 100° C./hour or more.

If this cooling end point is high, workability such as rollability will deteriorate, so cooling is performed at the above-mentioned average cooling rate up to 300°C. After hot rolling, cold rolling is performed without annealing, or if it is necessary to further improve the magnetic properties, hot rolled sheet annealing is performed at 500 to 1000°C for 5 seconds to 15 minutes, and then , cold rolled.

Hot-rolled sheet annealing is performed within the above temperature and time ranges at 500
This is because if the temperature is lower than ℃ or shorter than 5 seconds, the annealing effect which further enhances the magnetic properties cannot be achieved.
If the temperature exceeds 0° C. or 15 minutes, the crystal grains will become coarse, leading to sheet breakage during cold rolling and a decrease in the strength of the final product.

After cold rolling, annealing is performed at 700 to 900°C for 5 seconds to 15 minutes.
A sufficient annealing effect for reducing core loss and improving magnetic flux density cannot be achieved, and rolling structures remain or flatness remains unimproved. If the temperature exceeds 900°C or exceeds 15 minutes, the crystal grains will become coarse, resulting in a decrease in strength and a high tensile strength steel plate will not be obtained.

In annealing this cold-rolled sheet, decarburization may be carried out in a decarburizing atmosphere if necessary.

(Example) Example 1 C: 0.0025%, Si: 3.05%, M n :
1.40%, p+o, oxo%,'r, A*:o. 50
%, B: 0.0025%, with the remainder consisting of iron and unavoidable impurities.
5. Hot-rolled sheet hot-rolled at a winding temperature of 200 to 1000°C, after winding, the time to start cooling was varied from 0 to 6 hours, and cooled to 250°C at an average cooling rate of 100°C/hour. A repeated bending test was conducted.

'The results are shown in Figure 1. From the same figure, in the case of this component system, the relationship between hot-rolled plate thickness, coiling temperature, time from coiling to the start of cooling at 100°C per hour, and hot-rolled plate brittleness is , a clear correlation is observed. When the following formula is satisfied, the number of repeated bending times is ≧3.

CT (°C) ≦-200xt (w) +1000, but 0.5≦t≦2.5 Moreover, (time from winding to start of cooling at 100°C or more per hour) 55 hours of hot rolling followed by no hot-rolled sheet annealing. , or hot rolled sheet annealing conditions (400~1100)tX (5~
900) seconds, and after cold rolling to a plate thickness of 0.5-, (650 to 925)'t:X3
Annealed for 0 seconds, mechanically heated and Wl 5150
The core loss of B50 and the magnetic flux density of B50 were measured.

In addition, an Epstein test piece (half in the rolling direction and half in the perpendicular direction) of 30 mm x 320 M was used for the magnetic measurement.

The results are shown in Table 1.

Magnetic 1.4.5.7.8 which could not be cold rolled due to embrittlement fracture
．． 9.11.12.14.17.18.19.20,2
Among 1 and 22, 12 have a high hot-rolled plate annealing temperature, and in all the others, the hot-rolled coiling temperature does not satisfy the above-mentioned relational expression between plate thickness and coiling temperature, and the number of repeated bending of the hot-rolled plate is low. has occurred twice or less.

Magnet 2.3.6.10, I3. manufactured under the conditions of the present invention.
15.16 was rolled without plate breakage, yield strength YP was 55 to 68 kg/grave ■2, and high tensile strength TS was 60.
It has high strength characteristics of ~76 kg/ss'', and is also excellent in iron loss Wl 5150 and magnetic flux density B50.

Example 2 C: 0.0015-0.0045% by weight, si72
．． 8-3.23%, Mn: 0.04%-3.05%, p
:0.005~0.50%, A1:0.50~2.00
%, n:o, ooo~0.0100%, Ni:0.75
~1.80%, with the remainder consisting of iron and unavoidable impurities, was hot rolled to a Fi thickness of 2.01%.
After the hot-rolled coiling temperature was set to 400°C, the time from coiling to the start of cooling (average cooling rate 100°C/hour) was 30 minutes, and the hot-rolled sheet was annealed at 800°C for 30 seconds.
The mechanical properties and magnetic properties of a steel plate that had been cold rolled to a FiJγ of 0.5 mm and annealed at 750° C. for 30 seconds were measured.

The magnetic properties were determined by shearing a 30×320+U Epstein specimen by half from the rolling direction and from the right angle direction, and measuring the iron loss of Wl 5150 and the magnetic flux density of 850.

The results are shown in Table 2.

(The following margins are continued on the next page) As is clear from the results shown in Table 2, Samples 1 to 9 produced under the conditions of the present invention were rolled without plate breakage, and the yield strength YP was It has high strength properties with a tensile strength of 63 to 72 kg/Ryu 3 and a tensile strength of 71 to 82 kg/Ryu 2, and is also excellent in iron loss W15150 and magnetic flux density B50.

(Effects of the Invention) As described above, according to the present invention, a unidirectional electrical steel sheet with high strength and excellent magnetic properties, which is suitable as a material for ultra-high-speed rotating electric motors and electromagnetic switches, can be used as a material for ultra-high-speed rotating electric motors and electromagnetic switches. It is manufactured stably without any problems such as

[Brief explanation of drawings]

FIG. 1 is a chart showing the results of an investigation of the effects of coiling temperature and hot-rolled plate thickness on the number of repeated bending of a hot-rolled plate in an embodiment of the present invention. Agent Patent Attorney Tatsuo Chanoki

Claims (2)

[Claims] (1) In weight% C: 0.01% or less Si: 2.0% or more and 3.5% or less Mn: 0.1% or more and 10.0% or less P: 0.20% or less Al: 0.10% When hot rolling a slab containing 1.50% or less B: 0.008% or less, with the remainder consisting of iron and unavoidable impurities, the relationship with the hot-rolled plate thickness (t; mm) is expressed by the following formula: After winding at the indicated winding temperature (CT; °C) or lower, cooling is started within 5 hours after winding, and the average cooling rate is 100 °C or more per hour up to 300 °C, Unannealed or annealed at a temperature of 500°C or higher and 1000°C or lower for 5 seconds or more and 15 minutes or less, cold rolled, and then further annealed at a temperature of 700°C or higher and 900°C or lower for 5 seconds or more.
A method for producing a high tensile strength non-oriented electrical steel sheet, the method comprising annealing for a period of not less than 15 seconds and not more than 15 minutes. CT (℃)≦-200×t (mm)+1000 but 0
．． 5≦t≦2.5 (2) C: 0.01% or less Si: 2.0% or more and 3.5% or less Mn: 0.1% or more and 10.0% or less P: 0.20% or less Al: 0.10% When hot rolling a slab containing 1.50% or more B: 0.008% or less Ni: 6.0% or less, with the balance consisting of iron and unavoidable impurities, the hot-rolled plate thickness (t; mm) After winding at a winding temperature (CT; °C) shown by the following formula, cooling is started within 5 hours after winding, and the average cooling rate is 100 °C or more per hour up to 300 °C. Cool to a temperature of 1
Annealed at a temperature of 000°C or less for 5 seconds or more and 15 minutes or less, cold rolled, and then 5 seconds or more at a temperature of 700°C or more and 900°C or less.
A method for manufacturing a high tensile strength non-oriented electrical steel sheet, characterized by annealing for a period of not less than 15 seconds and not more than 15 minutes. CT (℃)≦-200×t (mm)+1000 but 0
．． 5≦t≦2.5