CN1183269C - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Abstract

A non-oriented electromagnetic steel sheet having a chemical composition in mass %: C: 0.005 % or less, Si: 1.5 to 3 %, Mn: 0.05 to 1.5 %, P: 0.05 % or less, S: 0.02 % or less, Al: 0.1 to 2 %, N: 0.005 % or less, Cr: 0.4 to 1.4 %, and balance: substantially Fe; a non-oriented electromagnetic steel sheet having a chemical composition in mass %: C: 0.005 % or less, Si: 4 % or less, Mn: 0.05 to 2 %, P: 0.1 % or less, S: 0.02 % or less, Al: 0.1 to 2 %, N: 0.005 % or less, Cr: 0.4 to 5 %, Ti: an amount satisfying Ti/C = 1 to 30, and balance: substantially Fe, provided that Mn / S >/= 10; a non-oriented electromagnetic steel sheet having a chemical composition in mass %: C: 0.01 % or less, Si: 1 to 4 %, Mn: 1 % or less, P: 0.05 % or less, S: 0.02 % or less, Al: 0.1 to 2 %, N: 0.005 % or less, Cr: 0.2 to 5 %, at least one of 0.05 to 0.5 % Cu, 0.002 to 0.1 % Sb and 0.002 to 0.1 % Sn, and balance: substantially Fe; and other two types of non-oriented electromagnetic steel sheet. Such non-oriented electromagnetic steel sheets are excellent in blanking characteristics and fatigue characteristics and are reduced in iron loss both before and after stress relieving annealing, and thus are very suitable as an iron core material of a motor for an electric car and an air conditioner and the like.

Description

Non-oriented electrical steel sheet and manufacturing method thereof

technical field

The present invention relates to a non-oriented electrical steel sheet with excellent stamping performance and fatigue performance, low iron loss after stress relief annealing with a frequency below 1000 Hz and a manufacturing method thereof.

Background technique

In recent years, from the point of view of electrical energy saving, the iron core material used in electrical appliances requires the use of non-oriented electrical steel sheets with lower iron loss. Generally, in order to reduce the iron loss of electrical steel sheets, it is effective to increase the resistivity by increasing the content of Si and Al. For example, the use of Si: 1.6-3.5%, Al : 0.2-2.5% steel, through the secondary cold rolling method of repeated cold rolling and annealing twice to reduce the iron loss. Japanese Patent Publication No. 56-22931 discloses that by adjusting the composition of steel to Si: 2.6-3.5%, Al: 0.3-1.0%, S: 0.0050% or less, O: 0.0025% or less, Japanese Patent Application Publication No. 5-140647 discloses A method of reducing iron loss by adjusting the composition of steel to Si: 2.0-4.0%, Al: 0.10-2.0%, S: 0.0030% or less, Ti, Zr, Nb, V: 0.0050% or less respectively.

On the other hand, from the viewpoint of miniaturization and efficiency improvement of electric vehicle motors and air conditioner motors, the frequency of these motors is developing toward a high frequency of 200-1000 Hz, and non-oriented electrical steel sheets used for motor cores are required , even at such high frequencies the iron loss is low. For this reason, Si: 4% or more is effective, but since the steel plate will become brittle, recently JP-A No. 11-229095 and JP-A-2000-119822 have proposed a Cr-containing steel that does not have the problem of embrittlement and has low iron loss. : Non-oriented electrical steel sheets with high Cr content of 0.5-5.5% and 1-8%.

However, if the content of Si and Al is increased, or the content of Cr is increased, the steel plate will be significantly hardened, so the mold is likely to be damaged during stamping, that is, the problem of deterioration of stamping performance occurs.

On the other hand, with the variable speed operation of the motor, the centrifugal force on the rotor also increases, so the electrical steel plate used for the iron core must have excellent fatigue performance. To improve the fatigue performance, it is effective to harden the steel sheet, but the above-mentioned problem of deterioration of the press workability occurs in the conventional method, and there is no non-oriented electrical steel sheet with excellent press workability and fatigue performance.

The iron cores of air compressor motors for high-efficiency air conditioners and refrigerators are stamped with non-oriented electrical steel sheets and then stacked together for stress relief annealing, so the iron loss after stress relief annealing is required to be low. However, even if the above-mentioned conventional electrical steel sheet has low iron loss before stress relief annealing, it may not necessarily be low after stress relief annealing.

Contents of the invention

The object of the present invention is to provide a non-oriented electrical steel sheet with excellent stamping performance and fatigue performance, low iron loss before and after stress relief annealing at a frequency below 1000 Hz, and a manufacturing method thereof.

The above objects can be achieved by the following non-oriented electrical steel sheets.

Contain mass % C: 0.0016-0.0029%, Si: 2.5-3.0%, Mn: 0.14-0.20%, P: 0.005-0.01%, S: 0.001-0.002%, Al: 1.0-1.5%, N: 0.0012- 0.0024%, Cr: 0.4-5%, Mg: 0.0001-0.005%, and the rest are non-oriented electrical steel sheets of Fe. This electrical steel sheet also has particularly excellent fatigue performance, and at the same time exhibits low iron loss at high frequencies.

The present invention also relates to a method for manufacturing a non-oriented electrical steel sheet, which includes the steps of: making the content of C: 0.005% or less, Si: 2.48-2.52%, Al: 0.98-1.02%, Mn: 0.17-0.19%, P: 0.010 -0.1 10%, N: 0.0014-0.0022%, S: 0.0003-0.0007%, Cr: 0.4-5%, and the rest is made of Fe steel into slabs; the above slabs are hot-rolled, pickled, and then cold-rolled to The thickness is specified, and then continuous annealing is carried out; the hot-rolled steel plate or the cold-rolled steel plate is subjected to decarburization treatment, so that the C content is 0.0003-0.0015%.

Description of drawings

Fig. 1 is a graph showing the relationship between Cr content, iron loss W15/50, and Vickers hardness Hv.

Fig. 2 is a graph showing the relationship between Hv and the number of times of punching.

Fig. 3 is a graph showing the relationship between Si+0.5×Al+0.2×Cr and (number of stamping times/W15/50).

Fig. 4 is a graph showing the relationship between Cr content and iron loss W10/400.

Fig. 5 is a graph showing the relationship between Ti/C and fatigue limit.

Fig. 6 is a graph showing the relationship between Cr content, iron loss W10/600, magnetic flux density B50, and Hv.

Fig. 7 is a graph showing the relationship between Mg content and fatigue limit.

Fig. 8 is a graph showing the relationship between Cu content and W10/400.

Fig. 9 is a graph showing the relationship between Sb content and W10/400.

Fig. 10 is a graph showing the relationship between the Sn content and W10/400.

Fig. 11 is a graph showing the relationship between Cr content and W10/400.

Fig. 12 is a graph showing the relationship between C content and W10/400.

Fig. 13 is a graph showing the relationship between Cr content and W10/400.

Detailed ways

We have conducted detailed research on the stamping performance, fatigue performance, and iron loss before and after stress-relief annealing with a frequency below 1000 Hz of non-oriented electrical steel sheets. Non-oriented electrical steel sheets of the above-mentioned 1-5 that have good performance and fatigue properties, and low iron loss before and after stress relief annealing at high frequency. Detailed description will be given below.

Embodiment 1. Non-oriented electrical steel sheet with excellent stamping performance

1) Reasons for limiting ingredients

C: It is necessary to make the C content 0.005% or less in order to prevent magnetic aging. In addition, in order to suppress an increase in hardness, which is detrimental to press workability, the C content is preferably 0.0009% or less.

Si: Since it increases the resistivity of the steel sheet, it is an effective element for reducing iron loss, but if it exceeds 3%, the hardness increases and the press workability deteriorates. Reducing the Si content can reduce the hardness, which is beneficial to improve the stamping performance, but the iron loss increases. In the present invention, the addition of Cr is used to suppress the increase of iron loss due to the reduction of Si content, but if the Si content is less than 1.5%, there is no such suppression effect.

Mn: If it exceeds 1.5%, the magnetic flux density will decrease significantly. In addition, in order to prevent hot embrittlement, the Mn content must be 0.05% or more.

P: If it exceeds 0.05%, the hardness increases remarkably and the press workability deteriorates. As will be described later, in order to effectively utilize Cr addition to achieve low hardness, the P content is preferably 0.01% or less.

S: If it exceeds 0.02%, MnS is precipitated and the iron loss increases. Since hot embrittlement may be caused when the Mn content is small, the S content is preferably 0.0009% or less.

Al: Like Si, it is an element that increases the electrical resistivity of a steel sheet, and if it exceeds 2%, the magnetic flux density will drop significantly. If it is less than 0.1%, fine AlN is completely precipitated, hindering the grain growth, resulting in high iron loss.

N: Since it precipitates in the form of AlN, the iron loss increases, so it should be 0.005% or less.

Cr: 0.4-1.4% is required for the reason described later.

The rest: basically Fe.

2) The relationship between Cr content and iron loss W15/50, Vickers hardness Hv

The steel smelted in the laboratory contains C: 0.0020%, Mn: 0.10%, P: 0.005%, S: 0.002%, Al: 1%, N: 0.0021%, so that the Cr content is at tr. (trace: basically 0%)-2.5%, in order to keep the resistivity of the steel plate unchanged, adjust the Si content so that Si+0.5Cr is 3%. After the above-mentioned steel is hot-rolled, it is heat-treated at 830°C×3hr in an atmosphere of 75%H ₂ -25%N ₂ , cold-rolled to a plate thickness of 0.35mm, and 950°C in an atmosphere of 10%H ₂ -90%N ₂ ×1min final annealing. Then measure the Hv of the steel plate surface and measure the average W15/50 in the rolling direction and the perpendicular rolling direction by Epstein iron loss measurement method.

As shown in Figure 1, it can be seen that W15/50 does not increase in the range of 0.4-1.4% Cr, but Hv decreases, and the stamping performance is excellent. If the Cr content exceeds 1.4%, the cause of the increase in Hv is considered to be the formation of a nitride layer on the surface of the steel sheet due to the high affinity between Cr and N.

When at least one of Ti: 0.005% or less and Nb: 0.005% or less is added after adding the above elements, the iron loss does not increase, and magnetic aging can be reliably prevented.

3) The relationship between Hv and stamping performance

The steel smelted in the laboratory contains C: 0.0025%, Mn: 0.20%, P: 0.01%, S: 0.002%, Al: 1%, N: 0.0021%, Cr: 1.0%, Ti: 0.001%, so that Si The content varies in the range of 1.5-3.0%. After the above-mentioned steel is hot-rolled _, it is heat-treated at 830℃×3hr in an atmosphere of 75%H ₂ -25%N _{2 .} Perform final annealing at 950°C for 1 min in an atmosphere of % N ₂ , and then coat the inorganic organic film. 10% of the ring-shaped samples with an inner diameter of 70 mm and an outer diameter of 100 mm were repeatedly punched, and the punching performance was evaluated by the number of punches with a burr height exceeding 50 μm. Since the burr height of the stamped material will increase if the stamping die is worn, the more stamping times the better the stamping performance of the material.

As shown in FIG. 2 , it can be seen that when Hv is set to 190 or less, the number of times of punching increases, and better punching performance can be obtained.

4) The relationship between Si+0.5×Al+0.2×Cr and stamping times/W15/50)

The steel smelted in the laboratory contains C: 0.0020%, Mn: 0.20%, P: 0.01%, S: 0.002%, N: 0.0020%, Ti: 0.001%, so that the contents of Si, Al, and Cr are within the scope of the present invention Internal change, after hot rolling the above-mentioned steel materials, heat treatment at 830℃×3hr in an atmosphere of 75%H ₂ -25%N ₂ , cold rolling to a plate thickness of 0.35mm, in an atmosphere of 10%H ₂ -90%N ₂ Perform final annealing at 950° C. for 1 min, and then apply an inorganic-organic film. Determination of W15/50 and the number of punches by the above method.

FIG. 3 shows the relationship between Si+0.5×Al+0.2×Cr and (number of stamping times/W15/50). Among them, Si+0.5×Al+0.2×Cr represents the solid solution strengthening rate considering the weighting of each element, and the greater the value, the higher the hardness. In addition, (the number of stamping times/W15/50) represents the balance between W15/50 and stamping performance. The larger this value is, the better the stamping performance is, and the smaller W15/50 is. It can be seen that if Si+0.5×Al+0.2×Cr is 2.3-3.5, the value of (number of stamping times/W15/50) is large, and the balance between W15/50 and stamping performance is better. On the other hand, when Si+0.5×Al+0.2×Cr is less than 2.3, excellent press workability can be obtained, but W15/50 is high. When Si+0.5×Al+0.2×Cr exceeds 3.5, W15/50 becomes low, and the press workability deteriorates.

(Example 1)

The molten steel smelted in a converter is degassed, and the steel 1-25 with the composition shown in Table 1 is smelted, cast into a slab, heated at 1140°C×1hr, and then hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 800°C and the coiling temperature is 610°C. The hot-rolled steel plate after coiling is heat-treated at 830°C×3hr in an atmosphere of 75% _H2-25 % _N2 , and cold-rolled to a thickness of 0.35mm in an atmosphere of 10% _H2-90 % _N2 Final annealing at 950°C for 1 min, followed by coating of an inorganic-organic film. Measure Hv, magnetic properties (W15/50 and magnetic flux density B50), and stamping times by the above methods.

The results are shown in Table 1.

The steels 3-5, 8, 15-18, 20, and 22-23 of the present invention have low W15/50 and good stamping performance.

On the other hand, the press workability of the comparative steel is not good, or W15/50 is high.

Table 1 steel C Si mn P S al N Cr Ti Nb Si+0.5Al+0.2Cr Hv Stamping times (×10 ⁴ ) W15/50(W/kg) B50(T) Stamping times/(W15/50)(×10 ⁴ ) Remark 1 0.0022 3.00 0.18 0.005 0.0020 1.00 0.0014 0.01 tr. tr. 3.50 210 50 1.95 1.66 26 comparative example 2 0.0021 2.90 0.18 0.005 0.0020 1.00 0.0015 0.20 tr. tr. 3.44 206 60 1.96 1.66 31 comparative example 3 0 0023 2.75 0.05 0 005 0.0020 1.00 0.0016 0.50 tr. tr. 3.35 189 145 1.94 1.66 75 Invention example 4 0.0029 2.53 0.17 0.005 0.0020 1.00 0.0024 0.95 tr. tr. 3.22 187 150 1.95 1.66 77 Invention example 5 0.0018 2.40 0.15 0.005 0.0020 1.00 0.0016 1.20 tr. tr. 3.14 186 155 1.96 1.65 79 Invention example 6 0.0018 2.10 0.15 0.005 0.0008 1.00 0.0015 1.80 tr. tr. 2.96 192 100 2.08 1.63 48 comparative example 7 0.0016 1.75 0.15 0.005 0.0009 1.00 0.0015 2.50 tr. tr. 2.75 195 95 2.16 1.62 44 comparative example 8 0 0035 2.53 0.15 0.010 0.0020 1.00 0.0028 0.95 0.0020 tr. 3.22 187 155 1.96 1.65 79 Invention example 9 0.0032 2.54 0.15 0.010 0.0020 1.00 0.0021 0.92 tr. 0.0020 3.22 187 160 1.97 1.65 81 comparative example 10 0.0030 4.20 0.15 0.018 0.0020 tr. 0.0019 0.70 tr. tr. 4.34 230 30 1.95 1.63 15 comparative example 11 0.0030 2.00 0.16 0.018 0.0020 2.50 0.0021 0.70 tr. tr. 3.39 190 130 2.01 1.60 65 comparative example 12 0.0022 3.00 1.80 0.021 0.0020 0.27 0.0019 0.70 tr. tr. 3.28 185 130 2.08 1.62 63 comparative example 13 0.0060 3.00 0.15 0.025 0.0020 0.26 0.0020 0.70 tr. tr. 3.27 195 90 2.63 1.63 34 comparative example 14 0.0012 3.00 0.16 0.021 0.0020 0.27 0.0065 0.70 tr. tr. 3.28 195 95 2.85 1.63 33 comparative example 15 0.0023 2.90 0.16 0.005 0.0020 0.80 0.0015 1.00 tr. tr. 3.50 190 150 2.00 1.67 75 Invention example 16 0.0020 2.40 0.16 0.005 0.0020 0.80 0.0017 1.00 tr. tr. 3.00 165 175 2.25 1.68 78 Invention example 17 0.0018 2.00 0.16 0.005 0.0020 0.80 0.0016 1.00 tr. tr. 2.60 145 180 2.40 1.70 75 Invention example 18 0.0018 1.60 0.16 0.005 0.0020 1.50 0.0016 1.00 tr. tr. 2.55 143 180 2.40 1.70 75 Invention example 19 0.0018 1.40 0.16 0.005 0.0020 1.30 0.0016 1.00 tr. tr. 2.25 128 190 3.20 1.70 59 comparative example 20 0.0018 2.00 0.16 0.005 0.0020 0.80 0.0016 1.00 tr. tr. 2.60 145 180 2.40 1.70 75 Invention example twenty one 0.0029 3.20 0.17 0.005 0.0020 0.70 0.0024 0.20 tr. tr. 3.59 199 80 2.00 1.66 40 comparative example twenty two 0.0018 3.00 0.17 0.005 0.0020 0.70 0.0020 0.40 tr. tr. 3.43 190 150 2.00 1.66 75 Invention example twenty three 0.0019 2.70 0.17 0.005 0.0020 0.70 0.0021 1.00 tr. tr. 3.25 178 160 2.05 1.65 78 Invention example twenty four 0.0019 2.35 0.17 0.005 0.0020 0.70 0.0021 1.70 tr. tr. 3.04 192 110 2.30 1.63 48 comparative example 25 0.0019 2.90 0.17 0.005 0.0020 0.70 0.0021 0.20 tr. tr. 3.29 184 153 2.70 1.65 57 comparative example

Embodiment 2. Non-oriented electrical steel sheet with excellent fatigue properties and low iron loss at high frequencies

1).Reason for limiting ingredients

C: In order to prevent magnetic aging, the C content is required to be 0.005% or less.

Si: is an effective element for increasing the electrical resistivity of the steel sheet, and if the Si content exceeds 4%, the magnetic flux density will decrease significantly.

Mn: If it exceeds 2%, the magnetic flux density will decrease significantly. In order to prevent hot brittleness, it is required to be more than 0.05%.

P: When the content exceeds 0.1%, the hardness increases remarkably, and the press workability deteriorates.

S: If it exceeds 0.02%, it precipitates as MnS and increases the iron loss.

Al: Like Si, it is an effective element for increasing the electrical resistivity of a steel sheet, but if it exceeds 2%, the magnetic flux density will drop significantly. If it is less than 0.1%, fine AlN will be precipitated, which hinders grain growth and increases iron loss.

N: Since it precipitates in the form of AlN, the iron loss increases, so it is required to be 0.005% or less.

Cr: 0.4-5% is required for reasons described later.

For the reason described later, it also contains Ti with Ti/C of 1-30 and Mn/S≥10 (Ti-containing steel), or Mg: 0.0001-0.005% (Mg-containing steel).

The rest: basically Fe.

2). Ti-containing steel

2-1). The relationship between Cr content and iron loss W10/400

The steel smelted in the laboratory contains C: 0.0020%, Si: 2.5%, Mn: 0.18%, P: 0.01%, S: 0.002%, Al: 0.7%, N: 0.0011%, so that the Ti content is tr. and 0.008%, Cr content changes in the range of tr.-6%. After the above-mentioned steel is hot-rolled, it is heat-treated at 830℃×3hr in an atmosphere of 75%H ₂ -25%N ₂ , and cold-rolled to a plate thickness of 0.35mm. Perform final annealing at 950°C×1min in an atmosphere of %H ₂ -80%N ₂ , then coat the semi-organic film, and sinter the film at 350°C. In order to simulate the driving state of the motor, heat treatment is carried out at 200°C×100hr, and then a ring-shaped sample with an inner diameter of 33mm and an outer diameter of 45mm is wound with 100 turns of wire on the side of the primary coil and the side of the secondary coil, and the W10/ at 400Hz is measured. 400.

As shown in Figure 4, it can be seen that the steel with a Ti content of 0.008% has significantly smaller W10/400 in the case of Cr: 0.4-5%, especially in the case of Cr: 0.4-0.9%. On the other hand, in steel with a Ti content of tr., the proportion of W10/400 decreases slightly, but tends to increase around Cr: 1%. The high iron loss in steel with a Ti content of tr. is considered to be the result of an increase in hysteresis loss due to the precipitation of fine Cr carbides.

2-2). The relationship between Ti/C and fatigue limit

The steel smelted in the laboratory contains Si: 2.5%, Mn: 0.18%, P: 0.01%, S: 0.002%, Al: 0.7%, N: 0.0010%, Cr: 0.8%, change the content of Ti and C, To change _the Ti/C, after the above steel is hot rolled _, heat treatment at 830°C×3hr in an atmosphere of 75%H ₂ -25%N ₂ , cold rolling to a plate thickness of 0.35mm, The final annealing was performed at 950°C for 1min in an atmosphere, and then the semi-organic film was coated, and the film was sintered at 350°C. In order to simulate the driving state of the motor, heat treatment was performed at 200°C×100 hr, and then the fatigue limit was measured by the following method.

That is, cut a sample with a width of 5mm and a length of 150mm from the heat-treated steel plate in the parallel rolling direction, grind the end parallel to the rolling direction with No. 800 emery paper, and use a stress ratio of 0.1 and a frequency of 20Hz. The fatigue test was carried out by partial pulse (tension-tension), and the stress amplitude without failure was taken as the fatigue limit under the condition of cycle number 10 ⁷ .

As shown in Fig. 5, it can be seen that when Ti/C is more than 1, the fatigue limit increases sharply, and when it is more than 5, it is almost saturated. This phenomenon is considered to be due to the addition of Ti to combine C and Ti, inhibiting the precipitation of Cr carbides. When Ti/C exceeds 30, the magnetic flux density decreases and the iron loss increases.

Therefore, to ensure that Ti/C is above 1, it is necessary to reduce the content of S that is easy to combine with Ti as much as possible, and Mn/S≥10 is required.

3). Mg-containing steel

3-1). The relationship between Cr content and iron loss W10/600, magnetic flux density B50, Hv

The steel smelted in the laboratory contains C: 0.0025%, Si: 2.5%, Mn: 0.20%, P: 0.01%, S: 0.002%, Al: 1.3%, N: 0.0021%, Mg: 0.003%, so that Cr The content varies between tr.-6%. After the above-mentioned steel is hot-rolled, it is heat-treated at 830°C×3hr in an atmosphere of 75%H ₂ -25%N ₂ , and cold-rolled to a plate thickness of _0.35mm. Perform final annealing at 950°C for 1 min in an atmosphere of -80% N ₂ , then coat the film, and sinter the film at 350°C. Measure Hv on the steel plate surface, and measure W10/600 and magnetic flux density B50 at 600 Hz with the above method.

As shown in Fig. 6, it can be seen that Cr: 0.4-5% range W10/600 decreased significantly. This phenomenon is considered to be the result of the combined effect of the reduction of eddy current loss due to the increase of resistivity, and the reduction of hysteresis loss due to the reduction of magnetic anisotropy.

In order to reduce the decrease in B50, Cr is 0.4-1.4%, preferably 0.4-0.9%.

3-2). The relationship between Mg content and fatigue limit

The steel smelted in the laboratory contains C: 0.0025%, Si: 3.05%, Mn: 0.20%, P: 0.01%, S: 0.002%, Al: 1.05%, N: 0.0018%, Cr: 0.95%, Mg content Change in the range of tr.-0.005%. After the above-mentioned steel is hot-rolled _, it is heat-treated at 830°C×3hr in an atmosphere of 75%H ₂ -25%N _{2 .} Final annealing at 950 °C for 1 min in an atmosphere of % _N2 . The fatigue limit was then determined by the method described above.

As shown in FIG. 7, it can be seen that the fatigue limit can be improved by adding the Mg content to 0.0001% or more, preferably 0.0005% or more. When the Mg content exceeds 0.005%, the cost increases. The effect of adding Mg was studied with an electron microscope, and it was found that the addition of Mg reduced the number of coarse Al ₂ O ₃ blocks, thereby increasing the fatigue limit.

In the case of adding Mg, the fatigue limit is improved by controlling Ti/C as described above, but this is also due to the decrease of coarse Al ₂ O ₃ blocks.

(Example 2)

The molten steel smelted in a converter is degassed, the steel 1-22 with the composition shown in Table 2 is smelted, cast into a slab, heated at 1140°C×1hr, and hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 800°C and the coiling temperature is 610°C. The hot-rolled steel sheet after coiling is heat-treated at 830°C×3hr in an atmosphere of 75%H ₂ -25%N ₂ , and cold-rolled to a thickness of 0.35mm in an atmosphere of 20%H ₂ -80%N ₂ Final annealing at 900°C for 1min, then coating with a semi-organic film, and sintering the film at 350°C. In order to simulate the driving state of the motor, heat treatment was carried out at 200°C×100hr, and then Hv, magnetic properties (W10/400, B50) and fatigue limit at 400Hz were measured by the above method.

The results are shown in Table 2.

Inventive steels 1-9 have low W10/400 and high fatigue limit.

On the other hand, the Cr-free steels 10 and 14 have high W10/400. Steel 10-12 with Ti/C less than 1 has a low fatigue limit. Steel 13 with Ti/C exceeding 30 has a high W10/400. Steel 15 with a Si content of more than 4%, steel 16 with an Al content of more than 2%, and steel 19 with a Mn content of more than 2% had low B50. Steel 17 with a Mn content of less than 0.05% has a high W10/400. Steel 18 having an Mn/S of less than 10 has a high W10/400 and a low fatigue limit. Steel 20 having a C content exceeding 0.005% has a high W10/400 and a low fatigue limit. Steel 21 having an N content of more than 0.005% and Steel 22 having an S content of more than 0.02% have high W10/400.

Table 2 steel C Si mn P S al N Cr Ti Mn/S Ti/C W10/400(W/kg) B50(T) Fatigue limit (MPa) Remark 1 0.0020 2.50 0.18 0.018 0.0010 1.00 0.0011 0.90 0.003 180 1.5 17.70 1.65 330 Invention example 2 0.0020 2.50 0.18 0.018 0.0010 1.00 0.0012 0.90 0.008 180 4.0 17.50 1.65 340 Invention example 3 0.0020 2.50 0.17 0.010 0.0010 1.00 0.0010 0.90 0.010 170 5.0 17.60 1.65 345 Invention example 4 0.0030 2.50 0.18 0.011 0.0010 1.00 0.0010 0.90 0.020 180 6.7 17.80 1.65 346 Invention example 5 0.0016 2.50 0.18 0.010 0.0010 1.00 0.0011 0.50 0.008 180 5.0 17.60 1.65 335 Invention example 6 0.0020 2.50 0.17 0.015 0.0020 1.00 0.0010 0.90 0.008 85 4.0 17.50 1.65 341 Invention example 7 0.0020 2.50 0.17 0.010 0.0020 1.00 0.0010 1.40 0.008 85 4.0 17.80 1.65 343 Invention example 8 0.0020 2.50 0.18 0.010 0.0020 1.00 0.0013 2.00 0.008 90 4.0 17.90 1.64 352 Invention example 9 0.0020 2.50 0.18 0.018 0.0020 1.00 0.0010 4.00 0.008 90 4.0 18.00 1.63 355 Invention example 10 0.0020 2.50 0.18 0.018 0.0010 1.00 0.0015 tr. tr. 180 0.0 18.50 1.67 340 comparative example 11 0.0020 2.50 0.18 0.018 0.0010 1.00 0.0020 0.90 tr. 180 0.0 18.60 1.66 300 comparative example 12 0.0020 2.50 0.22 0.018 0.0010 1.00 0.0012 0.90 0.001 220 0.5 18.50 1.66 300 comparative example 13 0.0015 2.50 0.18 0.011 0.0010 1.00 0.0015 0.90 0.050 180 33.3 19.00 1.63 350 comparative example 14 0.0020 2.50 0.18 0.012 0.0010 1.00 0.0010 tr. 0.010 180 5.0 18.60 1.67 340 comparative example 15 0.0025 4.20 0.18 0.018 0.0020 1.00 0.0022 0.90 0.010 90 4.0 16.40 1.61 396 comparative example 16 0.0020 2.50 0.18 0.018 0.0020 2.50 0.0021 0.90 0.010 90 5.0 16.50 1.60 362 comparative example 17 0.0022 2.50 0.02 0.020 0.0020 1.00 0.0010 0.90 0.010 10 4.5 18.70 1.64 356 comparative example 18 0.0020 2.50 0.05 0.021 0.0070 1.00 0.0015 0.70 0.010 7 5.0 18.50 1.60 302 comparative example 19 0.0020 2.50 2.25 0.021 0.0020 1.00 0.0019 0.70 0.010 1125 5.0 16.90 1.60 350 comparative example 20 0.0060 2.00 0.18 0.025 0.0020 1.00 0.0020 0.70 0.020 90 3.3 21.00 1.64 250 comparative example twenty one 0.0023 3.20 0.18 0.021 0.0020 1.00 0.0065 0.70 0.010 90 4.3 19.50 1.65 325 comparative example twenty two 0.0022 2.50 0.18 0.020 0.0300 1.00 0.0021 0.70 0.010 6 4.5 19.30 1.63 355 comparative example

(Example 3)

The molten steel smelted in a converter is degassed, the steel 1-22 with the composition shown in Table 3 is smelted, cast into a slab, heated at 1140°C×1hr, and then hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 800°C and the coiling temperature is 610°C. The hot-rolled steel sheet after coiling is heat-treated at 830°C×3hr in an atmosphere of 75%H ₂ -25%N ₂ , and cold-rolled to a thickness of 0.35mm in an atmosphere of 20%H ₂ -80%N ₂ Final annealing at 900 °C for 1 min. Then measure Hv, magnetic properties (W10/600, magnetic flux density B50) and fatigue limit at 600 Hz by the above method.

The results are shown in Table 3.

Steels 3-8 and 11-15 of the present invention have low W10/600 and high fatigue limit.

On the other hand, the W15/50 of the comparative steel is high or the fatigue limit is low.

table 3 steel C Si mn P S Al N Cr Mg W10/600(W/kg) B50(T) Hv Fatigue limit (MPa) Remark 1 0.0022 2.50 0.17 0.005 0.0010 1.50 0.0012 0.01 0.0003 40.00 1.67 190 350 comparative example 2 0.0021 2.50 0.16 0.005 0.0010 1.50 0.0015 0.20 0.0003 39.50 1.67 190 350 comparative example 3 0.0023 2.50 0.16 0.005 0.0010 1.50 0.0016 0.50 0.0003 33.80 1.67 192 352 Invention example 4 0.0029 2.50 0.17 0.005 0.0010 1.50 0.0024 0.95 0.0003 33.00 1.67 193 354 Invention example 5 0.0018 2.50 0.15 0.005 0.0010 1.50 0.0018 1.40 0.0003 32.00 1.66 195 355 Invention example 6 0.0026 2.50 0.15 0.005 0.0010 1.50 0.0015 1.80 0.0003 32.00 1.65 197 360 Invention example 7 0.0017 2.50 0.14 0.005 0.0010 1.50 0.0015 2.50 0.0003 32.50 1.64 200 362 Invention example 8 0.0016 2.50 0.18 0.005 0.0010 1.50 0.0015 4.50 0.0003 32.60 1.63 205 365 Invention example 9 0.0016 2.50 0.19 0.005 0.0010 1.50 0.0015 6.00 0.0003 35.20 1.62 210 370 comparative example 10 0.0029 2.80 0.17 0.005 0.0020 1.20 0.0020 0.90 tr. 33.00 1.67 203 310 comparative example 11 0.0028 2.80 0.17 0.005 0.0020 1.20 0.0021 0.90 0.0002 33.10 1.67 200 350 Invention example 12 0.0020 2.80 0.16 0.005 0.0020 1.20 0.0022 0.90 0.0003 33.05 1.66 200 360 Invention example 13 0.0022 2.80 0.17 0.005 0.0020 1.20 0.0024 0.90 0.0007 33.20 1.67 202 365 Invention example 14 0.0029 2.80 0.17 0.005 0.0020 1.20 0.0019 0.90 0.0020 33.10 1.66 203 365 Invention example 15 0.0020 2.80 0.17 0.005 0.0020 1.20 0.0024 0.90 0.0040 33.00 1.66 205 366 Invention example 16 0.0030 4.20 0.15 0.018 0.0020 1.00 0.0019 0.70 0.0007 34.00 1.61 230 400 comparative example 17 0.0030 3.00 0.16 0.018 0.0020 2.50 0.0021 0.70 0.0007 32.00 1.60 190 360 comparative example 18 0.0030 3.15 0.02 0.020 0.0020 0.80 0.0020 0.70 0.0007 40.50 1.64 210 370 comparative example 19 0.0022 3.15 2.20 0.021 0.0020 0.80 0.0019 0.70 0.0007 31.50 1.62 230 400 comparative example 20 0.0060 3.15 0.15 0.025 0.0020 0.80 0.0020 0.70 0.0006 40.05 1.64 210 370 comparative example twenty one 0.0023 3.15 0.16 0.021 0.0020 0.80 0.0065 0.70 0.0007 41.05 1.63 210 370 comparative example twenty two 0.0020 3.10 0.16 0.020 0.0300 0.80 0.0018 0.70 0.0007 41.20 1.63 200 360 comparative example

Embodiment 3. Non-oriented electrical steel sheet with low iron loss after high-frequency stress relief annealing

The present invention relates to a non-oriented electrical steel sheet that reduces iron loss after stress annealing by adding special elements such as Cu.

1). The reason for the restricted ingredients

C: An element that combines with Cr during stress annealing to form Cr carbides. If there are many Cr carbides formed, the iron loss after stress annealing will increase significantly, so it is required to be 0.01% or less.

Si: It can increase the resistivity of the steel plate, so it is an effective element for reducing iron loss, and the effect is small when it is less than 1%. On the other hand, if it exceeds 4.0%, the magnetic flux density will decrease significantly.

Mn: If it exceeds 1%, the magnetic flux density will decrease significantly.

P: When the content exceeds 0.05%, the hardness increases remarkably, and the press workability deteriorates. In order to effectively realize the effect of reducing hardness by adding Cr as described later, the P content is preferably 0.01% or less.

S: If more than 0.02%, MnS is precipitated and the iron loss increases.

Al: Like Si, it is an element that increases the electrical resistivity of a steel sheet, but if it exceeds 2%, the magnetic flux density decreases significantly. If it is less than 0.1%, fine AlN is precipitated, which inhibits grain growth and increases iron loss.

N: Precipitation in the form of AlN increases iron loss, so it is required to be 0.005% or less.

Cr: For reasons described later, the Cr content is required to be 0.2-5%.

For reasons described later, at least one element of Cu: 0.05-0.5%, Sb: 0.002-0.1%, and Sn: 0.002-0.1% is also contained.

The rest: basically Fe.

2). Relationship between Cu content and iron loss W10/400 after stress annealing

The steel smelted in the laboratory contains C: 0.0025%, Si: 2.5%, Mn: 0.2%, P: 0.01%, S: 0.0015%, Al: 1%, N: 0.0012%, so that the Cr content is tr. and 1%, Cu content changes at tr.-0.6%. After the above steel is hot-rolled, it is heat-treated at 830℃×3hr in an atmosphere of 75%H ₂ -25%N _{2 .} In the atmosphere of H ₂ -90% N ₂ , the final annealing was carried out at 950°C×1min, and then a ring-shaped sample with an inner diameter of 33mm and an outer diameter of 45mm was cut out, and a stress annealing was carried out at 750°C×2hr in an atmosphere of 100%H ₂ . Wind 100 turns of wire on one side of the primary coil and one side of the secondary coil, and then measure W10/400 at 400Hz.

As shown in Figure 8, it can be seen that when Cr is tr., even if Cu is added, W10/400 is almost unchanged, and when the Cr content is 1%, adding more than 0.05% Cu, W10/400 will change significantly reduced.

If the Cu content exceeds 0.5%, surface defects are likely to occur. It is effective to add Ni to reduce surface defects. In order not to increase iron loss, it is preferable to add Ni below 0.5%.

3). The relationship between Sb or Sn content and W10/400 after stress annealing

The same experiment as above was carried out, but instead of Cu, Sb or Sn varied at tr.-0.2%.

As shown in Figures 9 and 10, it can be seen that, as in the case of Cu, when Cr is tr., even if Sb or Sn is added, W10/400 is almost unchanged. On the other hand, when the Cr content is 1% Next, adding 0.002-0.1% of Sb or Sn, W10/400 will be greatly reduced.

4). The relationship between Cr content and W10/400 after stress annealing

The steel smelted in the laboratory contains C: 0.0025%, Si: 2.5%, Mn: 0.2%, P: 0.01%, S: 0.0015%, Al: 1%, N: 0.0012%, so that the Cu content is tr. and 0.2%, and the Cr content varies from tr. to 5%, and the test is carried out by the same method as above.

As shown in Figure 11, when the Cu content is tr., it is believed that the addition of Cr tends to increase W10/400, while when the Cu content is 0.2%, the W10/400 decreases significantly in the range of 0.2-5% Cr. , especially Cr is greatly reduced in the range of 0.4-1.4%.

Within the scope of the present invention, Cu, Sb, and Sn are added in combination, and a low W10/400 can also be obtained after stress annealing.

The non-oriented electrical steel sheets of the above-mentioned embodiments 1 to 3 can be produced by the same method as general non-oriented electrical steel sheets by adjusting only the specified composition range. That is, the molten steel smelted in a converter is degassed, adjusted to the specified composition, and hot rolled under normal conditions after casting. Then, the hot-rolled steel plate is directly cold-rolled or cold-rolled after annealing, or is inserted into an intermediate annealing for more than two times of cold-rolling, and then final annealing is performed. If the reduction of C content is insufficient during composition adjustment, decarburization is performed in an atmosphere of 5-30% H ₂ with a dew point of 10-30°C and the rest being N ₂ during annealing after hot rolling or during final annealing , can also reduce the C content.

(Example 4)

The molten steel smelted in a converter is degassed, and the steel 1-25 with the composition shown in Table 4 is smelted, cast into a slab, heated at 1140°C×1hr, and then hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 800°C and the coiling temperature is 610°C. The hot-rolled steel plate after coiling is heat-treated at 830°C×3hr in an atmosphere of 75% _H2-25 % _N2 , and cold-rolled to a thickness of 0.35mm in an atmosphere of 10% _H2-90 % _N2 Final annealing at 980°C×50sec. Then cut a ring-shaped sample with an inner diameter of 33mm and an outer diameter of 45mm, and perform stress annealing at 750°C×2hr in a 100% _H2 atmosphere, wind 100 turns of wire on both the primary coil side and the secondary coil side, and then measure 400Hz Under W10/400, magnetic flux density B50. For the coiled hot-rolled steel sheet of Steel 7 in Table 4, decarburization treatment was performed at 720°C for 1 hr in an atmosphere of 10% H ₂ -90% N ₂ with a dew point of +17°C, and then 860°C ×3hr heat treatment.

The results are shown in Table 4.

After the steel 1-18 of the present invention is stress annealed, a low W10/400 is obtained.

On the other hand, steels 9 and 20 with Cu, Sb and Sn contents outside the range of the present invention, steel 21 with C content outside the range of the present invention, steels 22 and 23 with Cr contents outside the range of the present invention, and Al contents within the range of the present invention Out of range steel 25, W15/50 high after stress annealing. In addition, the steel 24 whose Mn content is outside the range of the present invention has a low magnetic flux density.

Table 4 steel C Si mn P S Al N Cr B Cu Ni Sb sn W10/400(W/kg) B50(T) Remark 1 0.0018 2.5 0.18 0.010 0.0004 1.0 0.0012 1.0 tr. 0.07 0.01 tr. tr. 17.4 1.68 Invention example 2 0.0028 2.5 0.18 0.010 0.0012 1.1 0.0015 1.1 tr. 0.30 0.01 tr. tr. 16.7 1.67 Invention example 3 0.0014 2.4 0.19 0.010 0.0003 1.0 0.0010 0.9 tr. 0.30 0.30 tr. tr. 16.8 1.67 Invention example 4 0.0018 2.6 0.22 0.005 0.0015 1.0 0.0018 1.0 tr. 0.01 0.01 0.0024 tr. 17.6 1.68 Invention example 5 0.0016 2.5 0.18 0.007 0.0008 1.1 0.0024 1.1 tr. 0.01 0.01 0.012 tr. 17.0 1.68 Invention example 6 0.0030 2.4 0.16 0.012 0.0011 1.1 0.0014 1.0 tr. 0.01 0.01 0.05 tr. 16.5 1.68 Invention example 7 tr. 2.4 0.16 0.012 0.0011 1.0 0.0015 1.0 tr. 0.01 0.01 0.05 tr. 16.3 1.68 Invention example 8 0.0012 2.5 0.05 0.002 0.0005 1.0 0.0012 1.2 tr. 0.01 0.01 0.09 tr. 16.9 1.67 Invention example 9 0.0018 2.5 0.16 0.010 0.0002 1.0 0.0013 1.1 0.0008 0.01 0.01 0.05 tr. 16.8 1.67 Invention example 10 0.0017 2.5 0.21 0.015 0.0012 1.0 0.0016 1.0 tr. 0.10 0.10 0.02 tr. 16.7 1.67 Invention example 11 0.0022 2.5 0.12 0.012 0.0020 1.1 0.0014 1.0 tr. 0.01 0.01 tr. 0.03 17.2 1.68 Invention example 12 0.0014 1.3 0.35 0.020 0.0014 1.4 0.0012 1.4 tr. 0.01 0.01 0.05 tr. 17.8 1.69 Invention example 13 0.0013 3.4 0.02 0.004 0.0014 1.0 0.0012 0.9 tr. 0.01 0.01 0.04 tr. 15.2 1.62 Invention example 14 0.0015 2.5 0.14 0.015 0.0012 0.3 0.0015 1.1 tr. 0.01 0.01 0.05 tr. 17.8 1.69 Invention example 15 0.0013 2.5 0.18 0.012 0.0006 1.3 0.0014 0.25 tr. 0.01 0.01 0.04 tr. 17.3 1.70 Invention example 16 0.0019 2.4 0.15 0.010 0.0007 1.2 0.0012 0.43 tr. 0.01 0.01 0.05 tr. 17.0 1.69 Invention example 17 0.0012 2.5 0.12 0.008 0.0003 1.0 0.0015 1.5 tr. 0.01 0.01 0.05 tr. 17.2 1.66 Invention example 18 0.0024 2.5 0.12 0.007 0.0004 1.0 0.0011 4.5 tr. 0.01 0.01 0.05 tr. 17.8 1.62 Invention example 19 0.0023 2.5 0.17 0.012 0.0005 1.1 0.0015 1.0 tr. 0.01 0.01 tr. tr. 18.7 1.66 comparative example 20 0.0022 1.3 0.35 0.020 0.0008 1.4 0.0017 1.4 tr. 0.01 0.01 tr. tr. 20.7 1.66 comparative example twenty one 0.0120 2.5 0.18 0.014 0.0012 1.0 0.0021 1.1 tr. 0.01 0.01 0.05 tr. 19.5 1.68 comparative example twenty two 0.0014 2.5 0.16 0.012 0.0014 1.0 0.0028 0.03 tr. 0.01 0.01 0.05 tr. 18.4 1.69 comparative example twenty three 0.0012 2.5 0.16 0.009 0.0012 1.0 0.0021 5.8 tr. 0.01 0.01 0.05 tr. 18.0 1.61 comparative example twenty four 0.0018 2.5 1.20 0.008 0.0009 1.1 0.0022 1.2 tr. 0.01 0.01 0.04 tr. 18.0 1.61 comparative example 25 0.0019 2.5 0.20 0.008 0.0008 0.01 0.0022 1.3 tr. tr. 0.01 0.04 tr. 19.8 1.62 comparative example

(Example 5)

In addition to stress annealing, electrical steel sheets for iron cores of induction motors and DC motors are sometimes subjected to bluing treatment and thermal charging treatment at a temperature range of 300-600°C. In order to observe the effect of adding Sb in such a treatment, steel 1-3 with the composition shown in Table 5 was smelted, and a ring-shaped sample was cut from the finished annealed steel plate in the same way as in Example 4, and steel 2, 3 The samples were then treated at 550°C×1hr to measure W10/400 and B50.

The results are shown in Table 5.

Steel 2 without Sb has increased W10/400 after bluing treatment, while Steel 3 with Sb added can get low W10/400 even after bluing treatment. Effective. This phenomenon is considered to be due to the addition of Sb to suppress the precipitation of Cr carbides during the bluing treatment.

The W10/400 in Table 5 is higher than the W10/400 in Table 4. This is because the temperature of the bluing treatment is lower than the stress relief annealing temperature, and the grain growth is insufficient.

table 5 steel C Si mn P S Al N Cr B Cu Ni Sb sn W10/400(W/kg) B50(T) Remark 1 0.0023 2.5 0.17 0.012 0.0005 1.0 0.0015 1.0 tr. tr. tr. tr. tr. 19.5 1.66 Finished product after annealing 2 0.0023 2.5 0.17 0.012 0.0005 1.0 0.0015 1.0 tr. tr. tr. tr. tr. 20.5 1.66 After bluing 3 0.0025 2.5 0.17 0.012 0.0005 1.0 0.0016 1.0 tr. tr. tr. 0.05 tr. 19.2 1.66 After bluing

Embodiment 4. Non-oriented electrical steel sheet with low iron loss after high-frequency stress annealing

The invention relates to a non-oriented electrical steel sheet with low iron loss after stress annealing by reducing the C content.

1).Reason for limiting ingredients

C: For reasons described later, it is required to be 0.0015% or less.

Si: If it exceeds 4.0%, the magnetic flux density will be greatly reduced. Since it is an effective element to increase the electrical resistivity of the steel sheet and reduce iron loss, it is desirably 1.0% or more.

Mn: If it exceeds 2%, the magnetic flux density will be greatly reduced. In order to prevent hot embrittlement, more than 0.05% is required.

P: When the content exceeds 0.1%, the hardness increases remarkably, and the press workability deteriorates.

S: If it exceeds 0.02%, MnS will be precipitated and the iron loss will increase.

Al: Like Si, it is an element that increases the electrical resistivity of a steel sheet, and if it exceeds 2%, the magnetic flux density decreases significantly. It is desirable to be at least 0.1% in order to prevent an increase in iron loss due to fine AlN precipitation.

N: It is precipitated in the form of AlN, and the iron loss increases, and it is required to be below 0.005%.

Cr: For reasons described later, it is required to be in the range of 0.4-5%.

The rest: basically Fe.

2). Relationship between C content and iron loss W10/400 after stress annealing

The steel smelted in the laboratory contains C: 0.0050%, Si: 2.5%, Mn: 0.18%, P: 0.01%, S: 0.0005%, Al: 1.0%, N: 0.0020%, Cr: 1.0%, hot rolled Then, under the decarburization treatment conditions shown in Table 6, decarburize to the C content shown in Table 6. Then heat treatment at 860°C×3hr in 100% _H2 atmosphere, cold rolling to 0.35mm thickness, final annealing at 1000°C×1min in 10% _H2-90 % _N2 atmosphere, and then cut out the inner diameter of 33mm 1. A ring-shaped sample with an outer diameter of 45mm is subjected to stress annealing at 750°C×2hr in a 100% H ₂ atmosphere, and 100 turns of wire are wound on both the primary coil side and the secondary coil side, and the W10/400 at 400Hz is measured .

As shown in FIG. 12 , it can be seen that W10/400 after stress annealing decreases sharply when the C content is reduced to 0.0015% or less. If the C content is 0.0009% or less, lower W10/400 can be obtained.

Observe the samples with a C content of 0.0003-0.0035% with a scanning electron microscope. Cr carbides are observed at the grain boundaries and within the grains of the samples with a C content of 0.0035%, but not observed in the samples with a C content of 0.0003%. Cr carbides. Therefore, when the C content is below 0.0015%, the reason for the decrease of W10/400 is considered to be due to the inhibition of Cr carbide precipitation.

Table 6 Processing No. atmosphere Dew point (℃) temperature(℃) C content after treatment (%) A - - - 0.0050 B 15% _H2-85 % _N2 25 750 0.0003 C 15% _H2-85 % _N2 twenty two 750 0.0005 D. 15% _H2-85 % _N2 20 750 0.0007 E. 15% _H2-85 % _N2 18 750 0.0009 f 20% _H2-80 % _N2 18 750 0.0012 G 10% _H2-90 % _N2 15 750 0.0014 h 15% _H2-85 % _N2 15 750 0.0016 I 15% _H2-85 % _N2 12 750 0.0018 J 15% _H2-85 % _N2 10 750 0.0025 K 20% _H2-80 % _N2 0 750 0.0035 L 15% _H2-85 % _N2 -10 750 0.0042

3). The relationship between Cr content and W10/400 after stress annealing

The steel smelted in the laboratory contains C: 0.0035%, Si: 2.5%, Mn: 0.18%, P: 0.01%, S: 0.0005%, Al: 1.0%, N: 0.0020%, so that the Cr content is within tr.- 5.5% change, after the above-mentioned steel is hot-rolled, decarburization annealing is performed at 750°C×2hr in an atmosphere of 15%H ₂ -85%N ₂ with a dew point of 25°C to make the C content 0.0005%. Then heat treatment at 860°C×3hr in 100% _H2 atmosphere, cold rolling to 0.35mm thickness, and final annealing at 1000°C×1min in 10% _H2-90 % _N2 atmosphere, and then use the above The same method was used to measure W10/400 after stress annealing.

As shown in Figure 13, it can be seen that W10/400 decreases significantly when Cr is above 0.4%, especially in the range of 0.4-1.4%. This phenomenon is considered to be the result of the combined effect of reduced eddy current loss due to increased resistivity and reduced hysteresis loss due to reduced magnetic anisotropy. In order to suppress the cost increase and reduce the B50, the Cr content is required to be below 5%.

The manufacturing method of the above-mentioned non-oriented electrical steel sheet is as follows. For example, the mass % is C: 0.005%, Si: 4% or less, Al: 2% or less, Mn: 0.05-2%, P: 0.1% or less, N: 0.005 % or less, S: less than 0.02%, Cr: 0.4-5%, and the balance is Fe, and under the conditions of the usual production of non-oriented electrical steel sheets, the above-mentioned slabs are hot-rolled, pickled and then cooled. After rolling to the specified thickness, the process of continuous annealing is carried out, and the hot-rolled steel plate or the cold-rolled steel plate is decarburized in an atmosphere of 5-30% H ₂ with a dew point of 10-30 ° C - the rest is N ₂ , so that C drops below 0.0015%.

(Example 6)

The molten steel smelted in a converter is degassed, and the steel 1-20 with the composition shown in Table 7 is smelted, cast into a slab, heated at 1140°C×1hr, and then hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 750°C and the coiling temperature is 610°C. The hot-rolled steel sheet after coiling is heat-treated at 860°C×3hr in an atmosphere of 100% _H2 , cold-rolled to a plate thickness of 0.35mm, and then heat-treated at 1000°C× _1min in an atmosphere of 10%H2-90% _N2 Final annealing. Then W10/400 and B50 after stress annealing were measured by the same method as above.

The results are shown in Table 7.

Steel 1-9 of the present invention has low W10/400 after stress annealing and high magnetic flux density.

On the other hand, steel 10 with a lower Cr content than the range of the present invention, steel 12-15 with a higher C content than the range of the present invention, and steels 19 and 20 with S and N outside the range of the present invention have high W15/50 after stress annealing . In addition, the steels 11, 16, 17, and 18 having Cr, Si, Al, and Mn contents higher than the range of the present invention have lower magnetic flux densities.

Table 7 steel C Si mn P S al N Cr W10/400(W/kg) B50(T) Remark 1 0.0003 2.50 0.18 0.010 0.0003 0.98 0.0018 0.45 16.6 1.67 Invention example 2 0.0009 2.49 0.17 0.011 0.0004 1.02 0.0019 0.85 16.5 1.67 Invention example 3 0.0006 2.52 0.19 0.012 0.0005 1.00 0.0022 1.38 16.5 1.66 Invention example 4 0.0005 2.51 0.17 0.110 0.0005 1.01 0.0022 1.60 16.9 1.66 Invention example 5 0.0015 2.51 0.18 0.012 0.0006 1.01 0.0018 2.50 17.1 1.64 Invention example 6 0.0003 2.50 0.18 0.012 0.0003 0.99 0.0015 1.00 16.5 1.66 Invention example 7 0.0005 2.48 0.17 0.011 0.0007 1.00 0.0014 0.98 16.5 1.66 Invention example 8 0.0009 2.52 0.18 0.012 0.0005 0.98 0.0018 1.02 16.6 1.66 Invention example 9 0.0015 2.50 0.17 0.011 0.0003 1.03 0.0016 1.03 17.3 1.66 Invention example 10 0.0005 2.51 0.19 0.010 0.0003 1.02 0.0019 tr. 18.0 1.68 comparative example 11 0.0007 2.49 0.17 0.011 0.0005 1.01 0.0022 5.50 17.3 1.58 comparative example 12 0.0018 2.49 0.19 0.010 0.0004 0.99 0.0015 0.99 18.6 1.66 comparative example 13 0.0025 2.50 0.18 0.012 0.0005 1.00 0.0013 1.01 18.9 1.66 comparative example 14 0.0035 2.48 0.19 0.010 0.0007 1.01 0.0016 0.97 19.3 1.66 comparative example 15 0.0050 2.50 0.18 0.011 0.0005 1.02 0.0018 1.00 20.0 1.66 comparative example 16 0.0006 4.50 0.17 0.010 0.0004 0.30 0.0020 0.82 16.0 1.61 comparative example 17 0.0007 2.47 0.19 0.011 0.0002 2.50 0.0018 1.03 16.6 1.60 comparative example 18 0.0004 2.52 3.00 0.012 0.0003 0.99 0.0018 1.01 16.7 1.59 comparative example 19 0.0005 2.51 0.17 0.011 0.0300 1.00 0.0022 1.00 19.5 1.65 comparative example 20 0.0006 2.49 0.18 0.012 0.0005 1.02 0.0065 1.02 19.2 1.65 comparative example

(Example 7)

Steel 1-3 shown in smelting table 8, with the method identical with embodiment 6, cut ring-shaped sample from the finished annealed steel plate, the sample of steel 2, 3 is carried out the bluing treatment of 550 ℃ * 1hr again, Determination of W10/400 and B50.

The results are shown in Table 8.

Steel 2 with a C content of 0.0030% increases in W10/400 after bluing treatment and finish annealing, and Steel 3 with a C content of 0.0005% can obtain a low W10/400 even after bluing treatment. It can be seen that although the C content is significantly low , is effective even after bluing treatment. This phenomenon is considered to be due to the low C content, which inhibits the precipitation of Cr carbides during the bluing treatment.

Table 8 steel C Si mn P S al N Cr W10/400(W/Kg) B50(T) Remark 1 0.0030 2.5 0.18 0.012 0.0003 1.0 0.0015 1.0 19.5 1.66 Finished product after annealing 2 0.0030 2.5 0.18 0.012 0.0003 1.0 0.0015 1.0 20.5 1.66 After bluing 3 0.0005 2.5 0.18 0.012 0.0003 1.0 0.0016 1.0 19.0 1.66 After bluing

(Embodiment 8)

The molten steel smelted in a converter is degassed, steel 1-25 with the composition shown in Table 9 is smelted, cast into a slab, heated at 1140°C×1hr, and then hot-rolled to form a hot-rolled steel plate with a thickness of 2.0mm . During hot rolling, the finishing temperature is 750°C and the coiling temperature is 610°C. The hot-rolled steel sheet after coiling is heat-treated at 860°C×3hr in an atmosphere of 100% _H2 , cold-rolled to a plate thickness of 0.35mm, and then heat-treated at 1000°C× _1min in an atmosphere of 10%H2-90% _N2 Final annealing. At this time, decarburization annealing was performed under the conditions shown in Table 10 in order to reduce the C content in the final annealing of the hot-rolled steel sheets after coiling of some steels before heat treatment or after cold rolling. Then W10/400 and B50 after stress annealing were measured by the same method as above.

The results are shown in Table 10.

Steel 1-12 of the present invention has low W10/400 after stress annealing and high magnetic flux density.

On the other hand, steel 13 with a lower Cr content than the range of the present invention, steel 15-20 with a higher C content than the range of the present invention, and steels 24 and 25 with S and N outside the range of the present invention have higher W15/50 after stress annealing. In addition, steels 14, 21, 22, and 23 with Cr, Si, Al, and Mn contents higher than the range of the present invention have lower magnetic flux densities.

Table 9 steel C Si mn P S Al N Cr 1 0.0039 2.51 0.19 0.012 0.0003 1.00 0.0015 0.45 2 0.0048 2.50 0.18 0.011 0.0005 0.99 0.0019 0.86 3 0.0040 2.51 0.19 0.012 0.0004 1.01 0.0018 1.35 4 0.0047 2.48 0.18 0.011 0.0005 0.98 0.0016 1.60 5 0.0039 2.51 0.19 0.011 0.0005 1.00 0.0018 2.48 6 0.0047 2.49 0.19 0.012 0.0003 1.01 0.0016 0.90 7 0.0038 2.50 0.18 0.011 0.0002 1.00 0.0015 0.95 8 0.0045 2.49 0.19 0.012 0.0004 1.01 0.0018 0.97 9 0.0047 2.51 0.17 0.011 0.0003 1.00 0.0022 1.00 10 0.0048 2.49 0.19 0.012 0.0004 1.01 0.0018 0.98 11 0.0045 2.52 0.17 0.110 0.0005 0.99 0.0020 0.99 12 0.0042 2.50 0.18 0.011 0.0005 1.00 0.0016 1.01 13 0.0040 2.49 0.17 0.011 0.0005 1.02 0.0018 tr. 14 0.0045 2.00 0.17 0.011 0.0005 1.01 0.0015 5.46 15 0.0020 2.52 0.17 0.011 0.0005 0.99 0.0016 0.98 16 0.0045 2.50 0.18 0.012 0.0004 1.00 0.0021 1.05 17 0.0045 2.51 0.19 0.012 0.0003 1.01 0.0018 0.99 18 0.0035 2.51 0.18 0.011 0.0005 1.00 0.0022 1.40 19 0.0035 2.51 0.19 0.011 0.0005 1.00 0.0020 1.40 20 0.0035 2.51 0.18 0.011 0.0005 1.00 0.0022 1.40 twenty one 0.0042 4.50 0.17 0.010 0.0004 0.30 0.0013 0.82 twenty two 0.0032 2.47 0.19 0.011 0.0002 2.50 0.0016 1.03 twenty three 0.0040 2.52 2.95 0.012 0.0002 0.99 0.0018 1.01 twenty four 0.0045 2.51 0.17 0.011 0.0300 1.00 0.0020 1.00 25 0.0039 2.48 0.18 0.012 0.0010 1.02 0.0065 1.03

Table 10 steel Decarburization C content after decarburization (%) W10/400(W/kg) B50(T) Remark when processing atmosphere Dew point (℃) temperature(℃) time 1 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0003 16.6 1.67 Invention example 2 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0005 16.5 1.67 Invention example 3 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0006 16.5 1.66 Invention example 4 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0010 16.9 1.66 Invention example 5 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0005 17.1 1.65 Invention example 6 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0003 16.5 1.66 Invention example 7 Hot rolling annealing 15% _H2-85 % _N2 twenty two 750 2 hours 0.0005 16.5 1.66 Invention example 8 Hot rolling annealing 15% _H2-85 % _N2 18 750 2 hours 0.0009 16.5 1.66 Invention example 9 Hot rolling annealing 10% _H2-90 % _N2 18 750 2 hours 0.0015 16.6 1.66 Invention example 10 Finished annealing 20% _H2-80 % _N2 25 700 1min 0.0014 16.6 1.66 Invention example 11 Finished annealing 15% _H2-85 % _N2 20 750 5min 0.0008 16.5 1.66 Invention example 12 Finished annealing 10% _H2-90 % _N2 15 800 10min 0.0003 16.5 1.66 Invention example 13 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0005 18.0 1.68 comparative example 14 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0009 17.3 1.58 comparative example 15 - - - - - 0.0021 18.6 1.66 comparative example 16 - - - - - 0.0046 19.2 1.66 comparative example 17 Hot rolling annealing 15% _H2-85 % _N2 12 750 2 hours 0.0018 18.6 1.66 comparative example 18 Hot rolling annealing 15% _H2-85 % _N2 10 750 2 hours 0.0025 18.9 1.66 comparative example 19 Hot rolling annealing 20% _H2-80 % _N2 0 750 2 hours 0.0035 19.3 1.66 comparative example 20 Hot rolling annealing 15% _H2-85 % _N2 -10 750 2 hours 0.0048 20.0 1.66 comparative example twenty one Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0006 16.0 1.61 comparative example twenty two Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0007 16.6 1.60 comparative example twenty three Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0004 16.7 1.59 comparative example twenty four Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0005 19.5 1.65 comparative example 25 Hot rolling annealing 15% _H2-85 % _N2 25 750 2 hours 0.0005 19.2 1.65 comparative example

Claims (5)

1. non-oriented electromagnetic steel sheet, containing quality % is C:0.0016-0.0029%, Si:2.5-3.0%, Mn:0.14-0.20%, P:0.005-0.01%, S:0.001-0.002%, Al:1.0-1.5%, N:0.0012-0.0024%, Cr:0.4-5%, Mg:0.0001-0.005%, and all the other are Fe.

2. non-oriented electromagnetic steel sheet as claimed in claim 1, Cr content are 0.4-1.4%.

3. the manufacture method of a non-oriented electromagnetic steel sheet, comprise operation: quality % is that C:0.005% is following containing, Si:2.48-2.52%, Al:0.98-1.02%, Mn:0.17-0.19%, P:0.010-0.110%, N:0.0014-0.0022%, S:0.0003-0.0007%, Cr:0.4-5%, and all the other make slab for the steel of Fe; Pickling after the above-mentioned slab hot rolling, be cold rolled to specific thickness then, carry out continuous annealing again; To the steel plate after the hot rolling or cold rolling after steel plate carry out carbonization treatment, make C content at 0.0003-0.0015%.

4. the manufacture method of non-oriented electromagnetic steel sheet as claimed in claim 3, wherein the carbonization treatment of carrying out makes C content at 0.0003-0.0009%.

5. as the manufacture method of each described non-oriented electromagnetic steel sheet in claim 3 or 4, wherein use slab with Cr:0.4-1.4% replaced C r:0.4-5%.

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