TWI665311B - Non-oriented electrical steel coil and method of forming the same - Google Patents

Abstract

The invention provides a non-directional electromagnetic steel coil and a manufacturing method thereof, wherein the manufacturing method includes hot rolling, cold rolling, first annealing, quenched and tempered rolling, and second annealing of an alloy embryo with a specific composition. Non-directional electromagnetic steel coil with good magnetic and mechanical properties.

Description

Non-directional electromagnetic steel coil and manufacturing method thereof

The invention provides a non-directional electromagnetic steel coil and a manufacturing method thereof, and in particular, relates to a non-directional electromagnetic steel coil that is easy to process and can save time for subsequent processing and heat treatment and a manufacturing method thereof.

Generally speaking, the electromagnetic steel coil produced by the semi-process is mainly used in the refrigerant compressor manufacturing industry. Since the manufacturing process of the compressor motor core mostly includes stress release annealing (SRA), it can be manufactured using semi-processed products that require annealing and are relatively inexpensive. The production process of semi-processed electromagnetic coils includes annealing and quenched and tempered rolling. The quenched and tempered rolling introduces strain energy into the electromagnetic steel coil, resulting in extremely high strength of the electromagnetic steel coil when it leaves the factory.

When the application side (such as a manufacturer of compressor motor cores) wants to make this electromagnetic steel coil into a compressor motor core, it is necessary to first punch this electromagnetic steel coil to form an iron core, and perform stress relief on this iron core. In the annealing process, when stamping, the high-strength electromagnetic coil damages the stamping die. On the other hand, in order for the core to obtain sufficient kinetic energy for grain growth, it takes a long time (to 6 hours less) and high temperature (not less than 750 ° C) stress relief annealing process, thereby increasing manufacturing costs. In addition, after a long time stress-relief annealing process, the strength of the iron core is significantly reduced, resulting in an increased probability of plastic deformation of the iron core during subsequent processing processes (such as rotor casting aluminum, shaft entry, stator winding, etc.), making Bad rate increased.

In view of the above problems, there is an urgent need to propose a non-directional electromagnetic steel coil and a manufacturing method thereof. This non-directional electromagnetic steel coil can have appropriate magnetic properties, and when the non-directional electromagnetic steel coil is processed at the application end, the time or temperature of the stress relief annealing process can be shortened. Furthermore, the non-directional electromagnetic steel coil has appropriate strength, which can reduce the damage to the mold during stamping, but maintains this appropriate strength after the stress relief annealing process to avoid plastic deformation caused by processing.

Therefore, one aspect of the present invention is to provide a method for manufacturing a non-directional electromagnetic steel coil, which is mainly adding another annealing process after the rolling of tempering to release the strain energy accumulated in the steel coil and induce the steel Grain growth in the roll.

Another aspect of the present invention is to provide a non-directional electromagnetic steel coil, which is produced by the above-mentioned method for manufacturing a non-directional electromagnetic steel coil. This non-directional electromagnetic steel coil has good iron loss value and magnetic flux, and has appropriate strength.

According to the above aspect of the present invention, a method for manufacturing a non-oriented electromagnetic steel coil is provided. In some embodiments, the manufacturing method includes the following step. First, an alloy embryo is provided, which contains 0.20 wt.% To 2.70 wt.% Silicon, not more than 0.6 wt.% Aluminum, not more than 0.10 wt.% Phosphorus, and not more than 1.10 wt.% Manganese. , The balance of iron and unavoidable impurities. Next, the alloy blank is subjected to a hot rolling step to form a hot rolled material. Then, a cold rolling step is performed on the hot rolled material to form a cold rolled material. After that, a first annealing step is performed on the cold-rolled material to form an annealed material. The first annealing step is performed at a temperature of 600 ° C to 800 ° C. Next, a quenched and tempered rolling step is performed on the annealed material to form a treated material, and the reduction rate of the quenched and tempered rolling step is 1.0% to 6.0%. Then, a second annealing step is performed on the treated material to obtain a non-directional electromagnetic steel coil, wherein the second annealing step is performed at a temperature of 700 ° C to 1000 ° C.

According to some embodiments of the present invention, the first annealing step is performed for 30 seconds to 90 seconds.

According to some embodiments of the present invention, the second annealing step is performed for 30 seconds to 90 seconds.

According to some embodiments of the present invention, the carbon content of the alloy embryo is not more than 40 ppm.

According to some embodiments of the present invention, after the second annealing step, the manufacturing method further includes a coating step.

According to some embodiments of the present invention, the temperature of the first annealing step is equal to or lower than the temperature of the second annealing step.

According to some embodiments of the present invention, after the coating step, the manufacturing method further includes a stamping step of the non-oriented electromagnetic steel coil.

According to some embodiments of the present invention, after the stamping step, the The manufacturing method further includes a stress relief annealing process.

According to the above aspect of the present invention, a non-directional electromagnetic steel coil is proposed, which is produced by using the above-mentioned manufacturing method of the non-directional electromagnetic steel coil, wherein the W15 / 50 iron loss value of the non-directional electromagnetic steel coil Less than 4.7W / Kg.

According to some embodiments of the present invention, the difference between the strength of the non-oriented electromagnetic steel coil and the strength of the non-oriented electromagnetic steel coil subjected to the stress relief annealing process is less than 10%.

100‧‧‧ Method

110‧‧‧ provide alloy embryo

120‧‧‧ hot-rolling step of alloy embryo to form hot-rolled material

130‧‧‧ cold rolling of hot rolled material to form cold rolled material

140‧‧‧ The first annealing step is performed on the cold-rolled material to form an annealed material

150‧‧‧ The quenched and tempered rolling step is performed to form a treated material

160‧‧‧ The second annealing step is performed on the treated material

170‧‧‧ performs a coating step to produce a non-directional electromagnetic steel coil

In order to make the above and other objects, features, advantages, and embodiments of the present invention more comprehensible, the detailed description of the drawings is as follows: [FIG. 1] is a non-directional electromagnetic according to some embodiments of the present invention A schematic flowchart of a method for manufacturing a steel coil.

FIG. 2A is an optical microscope image of a non-directional electromagnetic steel coil before a stress relief annealing process according to an embodiment of the present invention.

[FIG. 2B] An optical microscope image of a non-directional electromagnetic steel coil subjected to a stress relief annealing process according to an embodiment of the present invention.

3A is an optical microscope image of a non-oriented electromagnetic steel coil of a comparative example before being subjected to a stress relief annealing process.

3B is an optical microscope image of a non-oriented electromagnetic steel coil of a comparative example after being subjected to a stress relief annealing process.

An object of the present invention is to provide a non-directional electromagnetic steel coil and a method for manufacturing the same. The manufacturing method of the present invention includes an additional annealing step after the original semi-processed temper rolling, to increase the grain size. In the subsequent application of this non-directional electromagnetic steel coil, the increase in grain size helps Reduce the temperature and / or time of the stress relief annealing process. In addition, the strength of the steel coil can be appropriately reduced to reduce the loss of the mold in the subsequent stamping step. Even after the stress-relief annealing process, the non-directional electromagnetic steel coils produced by the method of the present invention can still maintain proper strength by adding solid solution strengthening elements to avoid non-directional electromagnetic coils in subsequent processing processes. Predetermined plastic deformation.

The semi-manufacturing process referred to in the present invention may include steps such as steel making, hot rolling, cold rolling, annealing, temper rolling, and coating in order.

The strength referred to herein in the present invention may include hardness, yield strength, tensile strength, and the like. In addition, before and after a specific process, the change in elongation usually reverses the change in strength. That is, when the change in elongation is small, it means that the electromagnetic steel coil maintains a certain strength before and after this specific process.

FIG. 1 is a schematic flowchart of a method for manufacturing a non-directional electromagnetic steel coil according to some embodiments of the present invention. Hereinafter, a method 100 for manufacturing a non-oriented electromagnetic steel coil according to the present invention will be described with reference to FIG. 1.

As shown in step 110 of FIG. 1, an alloy embryo is first provided. In some embodiments, this alloy embryo may include 0.20 weight percent (wt.%) To 2.70 wt.% Silicon, not more than 0.6 wt.% Aluminum, not more than 0.10 wt.% Phosphorus, not more than 1.10 wt. % Manganese, balance of iron and unavoidable impurities. In some examples, the above components can be smelted, cast, etc. And so on to obtain the alloy embryo. In some examples, the carbon content of this alloy embryo is less than or equal to 40 ppm.

Next, as shown in step 120, a hot rolling step is performed on the alloy blank to form a hot rolled material. Thereafter, as shown in step 130, a cold rolling step is performed on the hot rolled material to form a cold rolled material. The hot rolling step and the cold rolling step of the present invention can refer to the process parameters of the currently known manufacturing method of non-directional electromagnetic steel coils, which will not be repeated here.

Next, as shown in step 140, a first annealing step is performed on the cold-rolled material to form an annealed material. In some embodiments, the first annealing step may be performed, for example, at a temperature of 600 ° C to 800 ° C. In still other embodiments, the first annealing step may be performed for 30 seconds to 90 seconds.

Then, as shown in step 150, a quenched and tempered rolling step is performed on the annealed material to form a treated material. In some embodiments, the annealing material may be subjected to a temperature reduction step, and then the quenched and tempered rolling step may be performed, for example, the temperature is lowered to room temperature. In some embodiments, the cutting rate of this quenching and rolling step is 1% to 6%. In particular, the temperature and time of the first annealing step of the present invention are matched with the cutting rate of the specific quenched and tempered rolling step, so that the non-directional electromagnetic steel coil produced is subjected to subsequent stress relief. Before the annealing process, it can also have an appropriate iron loss value. Therefore, if the temperature or time of the first annealing step or the cutting rate of the quenched and tempered rolling step does not fall within the range disclosed by the present invention, the iron loss value of the non-oriented electromagnetic steel coil is too high. In the application of this non-directional electromagnetic steel coil, in order to reduce the excessively high iron loss value, it is necessary to lengthen the time for stress relief annealing or increase its temperature, thereby causing an increase in manufacturing costs.

Next, as shown in step 160, the first step is performed on the processing material. Two annealing steps to obtain non-directional electromagnetic steel coils. In some embodiments, this second annealing step may be performed at a temperature of 700 ° C to 1000 ° C. In other embodiments, this second annealing step may be performed for 30 seconds to 90 seconds. In still other embodiments, the temperature of the aforementioned first annealing step is less than or equal to the temperature of the second annealing step. This second annealing step has a heat leveling function, which can improve the shape of the rolled steel after quenching and tempering, increase the yield rate, can also grow the grains to an appropriate size, and reduce the strength of the treated material. The reduction in strength referred to herein refers to maintaining the non-directional electromagnetic steel coil with proper strength. When the non-directional electromagnetic steel coil is subjected to a subsequent processing process (such as a stamping step), damage to the stamping die can be reduced. In addition, since the growth of the grains contributes to the reduction of the iron loss, the second annealing step is used to grow the grains to an appropriate size, which can make the time of the annealing process (such as the stress relief annealing process) required for the subsequent processing process. Or the temperature decreases, but it can still have a low iron loss value. In other words, the second annealing process is intended to share the annealing process required when applying this non-directional electromagnetic steel coil, in order to simplify the application-side process. Therefore, if the time or temperature of the second annealing process does not fall within the above range, the above effects cannot be achieved.

In some embodiments, the non-directional electromagnetic steel coil may have an average grain size of 50 μm to 100 μm before performing stress relief annealing. In other embodiments, the non-oriented electromagnetic steel coil may have a W15 / 50 iron loss value of less than 4.7 W / Kg before the stress relief annealing is performed.

Optionally, a coating step may be performed after the second annealing process, as shown in step 170. This coating step may include chromium-containing coating coating or chromium-free coating coating, the main purpose of which is to increase the corrosion resistance of non-directional electromagnetic steel coils. It may be performed using any known coating step, and the present invention is not particularly limited.

In some embodiments, the non-directional electromagnetic steel coil may be applied to manufacturing a motor core of a refrigerant compressor or any other field involving an annealing process in a subsequent processing process. In some embodiments, the non-directional electromagnetic steel coil may be slit, stamped, and riveted (or welded) to form an iron core. The non-directional electromagnetic steel coil of the present invention has appropriate strength, so the damage to the mold is small during punching.

After that, the core can be subjected to a stress relief annealing process to introduce thermal energy to further grow the grains and optimize the core loss value and magnetic flux of the core. In one example, the stress relief annealing process may be performed at, for example, 700 ° C. to 750 ° C. In other examples, the stress relief annealing process may be performed, for example, for 2 hours to 4 hours. After the core is annealed, steps such as stator winding / rotor casting of aluminum, and assembly of the motor can be performed to obtain a compressor motor. In particular, the non-directional electromagnetic steel coil obtained by using the non-directional electromagnetic steel coil manufacturing method of the present invention has good strength after the stress relief annealing process described above, so the stator winding, Probability of plastic deformation caused by processing steps such as rotor cast aluminum.

In some embodiments, the difference between the yield strength of the non-directional electromagnetic steel coil before the stress relief annealing process and the yield strength of the non-directional electromagnetic steel coil after the stress relief annealing process is less than 10%. In other embodiments, the difference between the tensile strength of the non-directional electromagnetic steel coil before the stress relief annealing process and the tensile strength of the non-directional electromagnetic steel coil after the stress relief annealing process is less than 10%. In still other embodiments, the non-directional electromagnetic steel coil after the stress relief annealing process may have an average grain size larger than 100 μm to 150 μm.

In the following, examples and comparative examples are used to specifically explain the implementation method and effect of the method for manufacturing a non-directional electromagnetic steel coil of the present invention.

Examples

In the embodiment, the non-directional electromagnetic steel coils formed after the aforementioned alloy embryos are subjected to hot rolling, cold rolling, first annealing step, quenched and tempered rolling, second annealing step, and coating. Wherein the first annealing step is performed at 700 deg.] C train 40 seconds, cutting and rolling step of temper was 3.5%, based on the second annealing step and 40 seconds at 950 ℃. The obtained non-oriented electromagnetic steel coil was measured for its W15 / 50 iron loss value, magnetic flux, hardness, yield strength, tensile strength and elongation. Thereafter, the non-oriented electromagnetic steel coil was die-cut, and a stress relief annealing process (SRA) was performed at 750 ° C for 2 hours, and the magnetic and mechanical properties were measured again. The evaluation results of the examples are shown in Table 1, FIG. 2A and FIG. 2B.

Comparative example

The comparative example was performed in the same manner as the example, except that the comparative example changed the parameters of each of the processes described above. Specifically, in the comparative example, the first annealing step was performed at 700 ° C. for 40 seconds, and the cutting rate of the quenched and tempered step was 3.5%, but the second annealing step was not performed. The evaluation results of the comparative examples are shown in Table 1, FIG. 3A, and FIG. 3B.

As can be seen from Table 1, using the manufacturing method of the non-directional electromagnetic steel coil of the present invention, before the stress relief annealing process is performed, the obtained non-directional electromagnetic steel coil already has a certain grain size (average particle diameter is about 70 μm, (As shown in Figure 2A), and its W15 / 50 iron loss value and B50 magnetic flux density are good. After the stress relief annealing process is performed, the W15 / 50 iron loss value of the non-directional electromagnetic steel coil of the embodiment can be further improved (the grains further grow, and the average particle diameter is about 120 μm, as shown in FIG. 2B), Maintain a good B50 magnetic flux density. In addition, the hardness, yield strength, tensile strength, and elongation of non-oriented electromagnetic steel coils did not change much before and after the stress relief annealing process. In other words, even after the stress relief annealing process is performed, the non-directional electromagnetic steel coil of the present invention can maintain good strength.

On the other hand, before the stress relief annealing process was performed, the electromagnetic steel coil of the comparative example had a high iron loss value of W15 / 50, a small grain size (as shown in FIG. 3A), a large hardness, and a low elongation. After the stress-relief annealing process, although the electromagnetic steel coil of the comparative example can reach the W15 / 50 iron loss value and B50 magnetic flux equivalent to the embodiment (the grain size has grown significantly, as shown in Figure 3B), its mechanical properties Significantly reduced, especially the drop strength and tensile strength are much lower than the non-directional electromagnetic steel coils of the examples. In other words, the comparative example not only needs to use a higher temperature or longer stress relief annealing process to achieve the predetermined magnetism, but the strength of the electromagnetic steel coil of the comparative example after this stress relief annealing process is also insufficient, which improves its use in subsequent processing processes. Risk of plastic deformation.

The application of the non-directional electromagnetic steel coil and the manufacturing method thereof can reduce the strength of the non-directional electromagnetic steel coil before leaving the factory, so that the application end uses When this non-directional electromagnetic steel coil is used, damage to the mold can be reduced, and the non-directional electromagnetic steel coil already has appropriate magnetic properties, and also reduces the temperature and / or the stress relief annealing process applied to achieve a specific magnetic property. Time, etc., thereby reducing manufacturing costs on the application side.

Although the present invention has been disclosed as above in the embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, so the scope of protection of the present invention shall be determined by the scope of the attached patent application.

Claims (9)

A method for manufacturing a non-directional electromagnetic steel coil, comprising: providing an alloy blank, containing 0.20 weight percent (wt.%) To 2.70 wt.% Silicon, not more than 0.6 wt.% Aluminum, not more than 0.10 wt.% Phosphorus, not more than 1.10 wt.% Manganese, not more than 40 ppm carbon, remaining iron, and unavoidable impurities; performing a hot rolling step on the alloy embryo to form a hot rolled material; the hot rolled material Performing a cold rolling step to form a cold rolled material; performing a first annealing step on the cold rolled material to form an annealed material, wherein the first annealing step is performed at a temperature of 600 ° C to 800 ° C; A quenched and tempered rolling step is performed on the annealed material to form a treated material, wherein a reduction rate of the quenched and tempered rolling step is 1.0% to 6.0%; a second annealing step is performed on the treated material to obtain A non-directional electromagnetic steel coil, wherein the second annealing step is performed at a temperature of 700 ° C. to 1000 ° C .; and performing a stress relief annealing process on the non-directional electromagnetic steel coil, wherein the stress relief annealing process is It is carried out at a temperature of 700 ° C to 750 ° C. The method for manufacturing a non-directional electromagnetic steel coil according to item 1 of the scope of the patent application, wherein the first annealing step is performed for 30 seconds to 90 seconds. The method for manufacturing a non-directional electromagnetic steel coil according to item 1 of the scope of patent application, wherein the second annealing step is performed for 30 seconds to 90 seconds. The method for manufacturing a non-directional electromagnetic steel coil according to item 1 of the scope of patent application, wherein after the second annealing step, the manufacturing method further includes a coating step. The method for manufacturing a non-directional electromagnetic steel coil according to item 1 of the scope of the patent application, wherein the temperature in the first annealing step is equal to or lower than the temperature in the second annealing step. The method for manufacturing a non-directional electromagnetic steel coil as described in item 4 of the scope of patent application, wherein after the coating step, the manufacturing method further includes a stamping step for the non-directional electromagnetic steel coil. The method for manufacturing a non-directional electromagnetic steel coil according to item 6 of the scope of the patent application, wherein the stress relief annealing process is performed after the stamping step. A non-directional electromagnetic steel coil is manufactured by using the method for manufacturing a non-directional electromagnetic steel coil as described in any one of claims 1 to 7, wherein the W15 / 50 iron loss value is less than 4.7W / Kg. The non-directional electromagnetic steel coil according to item 8 of the scope of the patent application, wherein the difference between the strength of one of the non-directional electromagnetic steel coils and the strength of one of the non-directional electromagnetic steel coils subjected to a stress relief annealing process Less than 10%.