KR101262465B1 - Wire rod having superior magnetic property and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a wire rod having excellent magnetic properties and a manufacturing method thereof, and more particularly, to a wire rod having excellent magnetic properties and a method for manufacturing the same, which can be used in transformers, automobiles, electrical and electronic products requiring low iron loss and high permeability. It is about.
The present invention is composed of weight%, C: 0.03-0.05%, Si: 3.0-5.0%, Mn: 0.1-2.0%, Al: 0.02-0.08%, N: 0.0015-0.0030%, balance Fe and other unavoidable impurities. The present invention provides a wire rod having excellent magnetic properties and a method of manufacturing the same, including a goth structure of 90 to 98.5 area%.
According to the present invention, it is possible to reduce the manufacturing cost by not using an expensive alloy element, it is possible to provide a wire rod having better magnetic properties through a conventional process rolling process without the addition of manufacturing equipment.

Description

Wire rod with excellent magnetic properties and manufacturing method {WIRE ROD HAVING SUPERIOR MAGNETIC PROPERTY AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a wire rod having excellent magnetic properties and a manufacturing method thereof, and more particularly, to a wire rod having excellent magnetic properties and a method for manufacturing the same, which can be used in transformers, automobiles, electrical and electronic products requiring low iron loss and high permeability. It is about.

As the core material of most medium and large transformers, directional or non-oriented electrical steel sheet is used. In particular, while requiring greater efficiency than the existing, the necessity of various research and development for the miniaturization and light weight of the mechanical device has emerged, and therefore, the development and research of high-quality oriented electrical steel sheet is very indispensable reality.

Particularly, since the grain-oriented electrical steel sheet is manufactured to be easy to magnetize in the rolling direction of the steel sheet and has high magnetic properties in the rolling direction, it is necessary to artificially form a texture showing magnetic properties by adding high Si to the ultra low carbon steel. However, in the case of the grain-oriented electrical steel sheet, in order to improve the magnetic properties, the Si component may contain about 6.5% or more to exhibit the characteristics of the grain-oriented electrical steel sheet.

In addition, in the case of a grain-oriented electrical steel sheet, in order to artificially form a Goss structure, which is an aggregate structure, it has a disadvantage of performing heat treatment in a high temperature and nitrogen atmosphere. This is because it is necessary to control the <100> crystal orientation, which is the crystal orientation for the maximum magnetic induction value.

On the other hand, although recently improved the way to improve the magnetic properties of the electrical steel sheet by controlling the texture or surface coating of the grain-oriented electrical steel sheet, in the case of the electrical steel sheet used as a transformer, Precise machining is required to suppress slit, shear, or warp, and when the iron core is relatively small, the machining itself becomes difficult, and the volume of the distortion part by the machining occupying the whole product of the iron core This becomes relatively large, which causes a problem that the magnetic properties are significantly reduced.

In order to solve this problem, a technology for manufacturing wire rods for small motors mounted on small transformers or automobiles by manufacturing electromagnetic wires or electric wires has been developed. When electrical steel sheets are made of wire rods, rolling and surface defects are suppressed. It does not require harsh process control and has the advantage of solving the problem of yield reduction by lamination of electrical steel sheet.

Such a representative technique is Japanese Patent Laid-Open No. 2001-115241. The patent is to manufacture a material for electronic steel wire excellent in drawing workability, in particular cold drawing workability even in the hot rolled state (As rolled), including Si in the range of 0.1 to 8% and at the same time the sum of C + N + O + S The component system is limited to less than 0.015%. However, in the case of the above patent, since the carbon component is controlled by ultra-low carbon, RH (Ruhrstahl-Heraues) degassing process should be added, and complex deoxidation should be performed with a long vacuum degassing time. It has the disadvantage of not being able to. In addition, since Cr is added in an amount of 0.1 to 15% to improve magnetic properties, it is not possible to solve the problem of price increase due to the addition of alloying elements.

As a technology complementing the above patent, there is Japanese Patent Laid-Open No. 2000-045051. The patent relates to an electronic steel wire having excellent iron loss and workability, in which the sum of the C, N, O, and S components is limited to 0.015% or less, and the grain size and the wire diameter after wire drawing are defined. : 2% or less, Al: 2% or less, Cu: 2% or less are added, and the steel wire which is excellent in iron loss and workability is disclosed. However, the electronic steel wire disclosed in the patent has the disadvantage that there is no problem of the source material price increase due to the increase in the addition amount of alloying elements, there is no magnetic proposal in the hot rolling state, and there is no specification of the aggregate fraction.

On the other hand, there is another invention disclosed in Japanese Unexamined Patent Publication No. 2001-131718, the patent is limited to the sum of the C, N, O, S components to 0.025% or less, wire rods of 0.01 ~ 1.0mm diameter manufactured through drawing Presenting. However, the patent also has the disadvantage that the addition of expensive alloying elements such as Cr, Ni, Cu is essential, there is no specific organizational proposal for magnetic and suggestion of magnetic value.

In particular, in the case of the above-described patents, all magnetic properties have the disadvantage that they have a value close to that of the non-oriented electrical steel sheet.

One aspect of the present invention is to use a general low carbon steel, not ultra low carbon steel, and to provide a wire rod and a method of manufacturing the same having better magnetic properties by activating the Goss structure in the wire rod through a common process rolling process. It is.

The present invention is composed of weight%, C: 0.03-0.05%, Si: 3.0-5.0%, Mn: 0.1-2.0%, Al: 0.02-0.08%, N: 0.0015-0.0030%, balance Fe and other unavoidable impurities. It provides a wire with excellent magnetic properties including 90 ~ 98.5 area% goth tissue.

At this time, the wire rod is preferably a saturation magnetic flux density of 280 ~ 350emu.

The present invention is in weight percent, consisting of C: 0.03-0.05%, Si: 3.0-5.0%, Mn: 0.1-2.0%, Al: 0.02-0.08%, N: 0.0015-0.0030%, balance Fe and other unavoidable impurities. A heating step of heating the steel at 1000 to 1100 ° C .; A ball rolling step of rolling the heated steel by wire; And it provides a method of producing a wire having excellent magnetic properties including the annealing step of heating the ball-shaped wire rod at a rate of 5 ~ 15 ℃ / s annealing at 650 ~ 850 ℃.

At this time, it is preferable to perform the said step of rolling at 900-1000 degreeC, and it is preferable to carry out by 30 to 60% of a cross-sectional reduction rate. After the cold rolling step, the cold rolled wire is preferably cooled at a rate of 0.1 ° C./s or less, and the annealing step is preferably performed for 2 to 7 hours. After the annealing step, the wire is preferably cooled to 150 ° C at a rate of 3 ° C / s or less. In addition, after the annealing step, the wire rod may be surface coated with at least one member selected from the group consisting of MgO, Al ₂ O ₃ , ZnO, and ZrO ₂ .

According to the present invention, it is possible to reduce the manufacturing cost by not using an expensive alloy element, it is possible to provide a wire rod having better magnetic properties through a conventional process rolling process without the addition of manufacturing equipment.

The inventors of the present invention, while conducting research for imparting excellent magnetic properties to general low carbon steel wire rods, have recognized that wire rods having high magnetic properties can be produced even by normal hot rolling by controlling compositional components. In this case, the hot rolling refers to the rolling of the rolling, by using the characteristics of the rolling rolling to produce a large amount of goose texture affecting the magnetic properties when the strain in the wire rod by unidirectional rolling causes the strain (Strain) The present invention has been completed by focusing on the fact that it can be made and that the wire rod having better magnetic properties can be produced when the annealing heat treatment step is added after the above-mentioned rolling.

Hereinafter, the present invention will be described in detail.

Carbon (C): 0.03-0.05 wt%

C is dissolved in the wire and causes lattice distortion and aging in processing, while reducing ductility. When the C is added at less than 0.03%, there is a problem in that it is not possible to form a uniform goth structure in the wire rod, and when it exceeds 0.05%, the magnetic content is lowered, so that the carbon content is 0.03 to 0.05%. It is preferable to limit.

Silicon (Si): 3.0-5.0 wt%

Si is an effective component to improve the iron loss and magnetism by increasing the electrical resistance of the wire, but if less than 3%, the magnetism is lowered due to the insufficient amount of addition, if it exceeds 5%, the work hardening during the rolling of the wire proceeds rapidly and can be rolled Since there is no disadvantage, the content of the silicon is preferably limited to 3.0 to 5.0% by weight.

Manganese (Mn): 0.1-2.0 wt%

Mn is a useful component that can improve the electrical resistance and improve the iron loss characteristics of the wire rod, but if it is added less than 0.1%, Mn can not play a role of compensating the strength when rolling, and when it exceeds 2.0%, it is processed like Si There is a problem that causes a hot rolling problem by increasing the curing effect. Therefore, the content of manganese is preferably limited to 0.1 ~ 2.0%.

Aluminum (Al): 0.02-0.08 wt%

In the case of Al, it is preferable to limit the content in conjunction with the nitrogen control range because it is an element effective for improving the magnetic properties through the control of nitrogen in the steel. When the Al is added less than 0.02% has the disadvantage that it can not effectively control the nitrogen, and when it is added exceeding 0.08%, Al may precipitate in the atomic state to lower the magnetism of the aluminum, The content is preferably limited to 0.02 to 0.08%.

Nitrogen (N): 0.0015 to 0.003 wt%

In the case of N, the formation of goth structure is suppressed through lattice deformation and nitride formation with alloying elements due to penetration into the crystal lattice, which causes aging and ductility deterioration. Nitrogen is controlled at less than 0.0015% because it is a very harsh process in the steelmaking process and cannot be implemented in the actual process.If it exceeds 0.003%, nitrogen in the steel can move freely and the Al content is increased to coarsen AlN. In order to make it possible, the content of nitrogen is preferably limited to 0.0015 to 0.003%.

By limiting the composition range as described above, excellent magnetic properties, that is, directivity, can be imparted to the wire rod. The wire rod of the present invention includes 90% of Goss structure (Goss Structure), such that a large amount of goose structure is generated as compared to the existing electrical steel sheet or a wire rod having magnetic properties, the wire material is excellent magnetic properties, that is, It has directionality. When the goth structure is less than 90%, the wire rod cannot be provided with directionality and thus has non-directional magnetic properties. That is, the more the goth tissue is generated, the better, but as a process limit, the upper limit of the goth tissue is limited to 98.5%.

In addition, the wire rod of the present invention preferably has a saturation magnetic flux density of 280 emu or more. When the saturation magnetic flux density is less than 280 emu, it is difficult to impart orientation to the wire rod and may have non-directional magnetic properties. The higher the saturation magnetic flux density, the higher the value as in the goth structure, the better the magnetic properties, but the upper limit is limited to 350emu due to process limitations.

As long as the wire rod of the present invention satisfies the above composition range, the ordinary wire rolling conditions and the annealing process alone have excellent magnetic properties. Therefore, the wire rod conditions and other manufacturing conditions are not particularly limited except for the annealing process.

However, an example of the manufacturing process of the wire rod for implementing the present invention more preferably is as follows.

First, heating is performed at 1000-1100 degreeC with respect to the steel material which satisfy | fills the composition range of this invention. If the heating temperature is less than 1000 ℃ in the wire process, extracting the steel from the furnace and rough rolling causes a problem of surface defects due to severe strain increase.If it exceeds 1100 ℃, the limit and surface scale of the furnace are increased. The quality of the product is reduced.

Subsequently, the reheated steel is subjected to ball rolling. The wire rolling is an essential process in the manufacture of wire rods. Through the rolling of the wire rods, a unidirectional rolling of the wires in the wire rod causes a strain, thereby causing the formation of a collective structure, that is, a Goss structure. You can activate the creation. As a result, it is possible to impart excellent magnetism to the wire rod even by performing the hot rolling in a hot state.

It is preferable to perform the cold rolling at 900 to 1000 ° C., but if it is less than 900 ° C., the process load may cause surface defects of the wire rod, and fracture of the wire rod roll may occur. If it exceeds 1000 ° C, the strain may not be effectively caused due to the ductility increase of the wire rod during rolling.

It is preferable that the reduction ratio of the cross section is 30 to 60% when the rolling is performed. When the reduction ratio is less than 30%, it is impossible to distribute the tissue to the magnetic wire due to insufficient strain due to the lack of strain. In the case of more than 60%, there is a possibility that severe stretching of the wire rod tissue may increase the recrystallization force and transform the goth tissue itself.

In addition, it is preferable to have a cooling process after the said rolling, and to cool at a rate of 0.1 degrees C / s or less. When the cooling rate exceeds 0.1 ° C / s, low-temperature tissue in the tissue appears to be more likely to transform into ferrite tissue.

After the cooling step, it is preferable to perform annealing treatment, and the annealing heat treatment is preferably performed by heating the completed wire rod at a rate of 5 to 15 ° C./s and maintaining it at 650 to 850 ° C. for 2 to 7 hours. The annealing process is important for generating more goth tissue in the steel sheet in the hot rolled state because the annealing treatment can impart a driving force to change direction toward the goth tissue through the other directional tissues around the goth tissue. It becomes a process. Through the annealing process, it is possible to secure more than 90% of the goth tissue, thereby providing excellent magnetic properties to the wire rod.

On the other hand, if the quenching rate is less than 5 ℃ / s, the thermal expansion during heating is low due to too slow heating rate, the thermal expansion rate to the tissue may be slow, if it exceeds 15 ℃ / s due to too fast heating rate It is possible that not enough heat can be transferred inside the organization. In addition, when the annealing temperature is less than 650 ℃, there is a possibility that a pearlite is generated, if the annealing temperature exceeds 850 ℃, the tissue itself may be transformed into austenite. In order to implement the effect of the annealing process preferably, annealing is preferably performed for 2 to 7 hours.

After the annealing treatment, the wire is preferably cooled to 150 ° C at a rate of 3 ° C / s or less. When the cooling rate exceeds 3 ° C / s, there is a possibility that low temperature tissue is generated due to the rapid cooling rate, by cooling to 150 ° C, the wire packaging is possible.

After the annealing treatment, the surface of the wire rod may be coated with at least one member selected from the group consisting of MgO, Al ₂ O ₃ , ZnO, and ZrO _2. The materials are representative materials having insulating properties. It can react with the surface oxide layer of the steel sheet produced during annealing to form a glassy film that improves interlayer insulation and can promote the removal of sulfur that inhibits magnetism.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are only for illustrating the present invention in more detail, but the scope of the present invention is not limited.

(Example)

Steel materials having the composition components shown in Table 1 below were prepared as wire rods using the process conditions described in Table 2 below. After measuring the fraction of the goose structure and the saturation magnetic flux density for the wire rod prepared above, the results are shown in Table 3 below. The annealing time during the production of the wire was 3 hours.

division Chemical composition (% by weight) C Si Mn P S Al N Comparative River 1 0.06 1.0 0.1 0.01 0.007 - 0.002 Comparative River 2 0.06 2.0 0.1 0.01 0.007 - 0.002 Comparative Steel 3 0.06 3.0 0.1 0.01 0.007 - 0.002 Comparative Steel 4 0.06 4.0 0.1 0.01 0.007 - 0.002 Inventive Steel 1 0.031 3.0 0.185 0.011 0.007 0.023 0.002 Invention river 2 0.045 3.1 0.15 0.01 0.007 0.020 0.002 Invention steel 3 0.042 3.2 0.99 0.01 0.007 0.040 0.002 Inventive Steel 4 0.047 3.26 0.98 0.01 0.007 0.041 0.002 Invention steel 5 0.044 3.05 0.98 0.01 0.007 0.08 0.002 Inventive Steel 6 0.03 3.0 0.1 0.01 0.007 0.02 0.002 Invention steel 7 0.03 3.0 0.1 0.01 0.007 0.04 0.002 Inventive Steel 8 0.03 5.0 0.1 0.01 0.007 0.02 0.002 Invention river 9 0.03 5.0 0.1 0.01 0.007 0.04 0.002

Specimen No. division Heating temperature
(℃) Mold Rolling Temperature (℃) section
Decrease (%) Cooling rate
(° C / s) Temperature rise rate
(° C / s) Annealing temperature
(℃) Cooling rate
(° C / s) Cooling stop
Temperature (℃) Comparative River 1 Comparison 1 1100 850 10 0.1 10 640 5 150 Comparative River 2 Comparative material 2 1100 900 20 0.1 11 740 5 150 Comparative Steel 3 Comparative material 3 1100 900 30 0.1 11 870 7 150 Comparative Steel 4 Comparison 4 1100 900 40 0.1 12 900 7 150 Inventive Steel 1 Inventory 1 1100 900 10 0.3 12 780 3 150 Invention river 2 Inventory 2 1100 900 30 0.1 13 800 3 150 Invention steel 3 Invention 3 1100 900 50 0.1 8 680 2 150 Inventive Steel 4 Invention 4 1100 900 40 0.1 15 800 2 150 Invention steel 5 Invention Article 5 1100 900 20 0.1 14 750 2 150 Inventive Steel 6 Comparative material 5 1100 900 10 0.2 4 640 5 150 Invention steel 7 Comparative material 6 1100 900 20 0.1 8 740 5 150 Inventive Steel 8 Comparative Material7 1100 850 30 0.1 14 870 7 150 Invention river 9 Comparative Material 8 1100 900 40 0.1 16 900 7 150

division Goth tissue fraction (area%) Saturated magnetic flux density (emu) Comparison 1 75.2 254.1 Comparative material 2 80.2 276.5 Comparative material 3 66.2 257.1 Comparison 4 70.1 266.1 Inventory 1 95.2 281.3 Inventory 2 96.7 287.5 Invention 3 98.3 293.3 Invention 4 97.1 289.6 Invention Article 5 95.4 283.1 Comparative material 5 74.1 257.4 Comparative material 6 79.2 260.1 Comparative Material7 78.7 259.1 Comparative Material 8 71.1 255.03

As can be seen from Tables 1 to 3, the inventive steels 1 to 5 satisfying the component system and manufacturing conditions proposed by the present invention can be seen that it has an excellent Goth structure fraction and saturation magnetic flux density.

However, Comparative Materials 1 to 4, which do not conform to the component system of the present invention, have a lower level of Goth tissue fraction and saturation magnetic flux density than those of the present invention. Particularly, Comparative Material 2 is manufactured to meet the manufacturing conditions of the present invention. However, it does not satisfy the composition component of the present invention, it can be seen that the magnetic properties are not high.

Comparative materials 5 to 8 satisfy the compositional components of the present invention, but do not satisfy the manufacturing conditions, it can be seen that the level of Goth tissue fraction and saturation magnetic flux density is low, through which the comparative materials 5 to 8 are invented It can be seen that the magnetic properties are significantly lower than that.

Claims (9)

By weight, C: 0.03-0.05%, Si: 3.0-5.0%, Mn: 0.1-2.0%, Al: 0.02-0.08%, N: 0.0015-0.0030%, balance Fe and other unavoidable impurities. Wire rod with excellent magnetic properties including ~ 98.5 area percent goth tissue.
The wire rod of claim 1, wherein the saturation magnetic flux density of the wire rod is 280 to 350 emu.
By weight%, 1000 steels consisting of C: 0.03-0.05%, Si: 3.0-5.0%, Mn: 0.1-2.0%, Al: 0.02-0.08%, N: 0.0015-0.0030%, balance Fe and other unavoidable impurities A heating step of heating at ˜1100 ° C .;
A ball rolling step of rolling the heated steel by wire; And
The method of manufacturing a wire having excellent magnetic properties comprising the annealing step of heating the eutectic rolled wire at a rate of 5 ~ 15 ℃ / s at 650 ~ 850 ℃.
The method of manufacturing a wire rod according to claim 3, wherein the step of rolling the mold is performed at 900 to 1000 ° C.
The method of manufacturing a wire rod having excellent magnetic properties according to claim 3, wherein the step of rolling is performed at a reduction ratio of 30 to 60%.
The method of manufacturing a wire having excellent magnetic properties according to claim 3, wherein the wire is rolled at a rate of 0.1 ° C./s or less after the step of rolling.
4. The method of claim 3, wherein the annealing step is performed for 2 to 7 hours.
The method of claim 3, wherein after the annealing step, the wire is cooled to 150 ° C. at a rate of 3 ° C./s or less.
The method of claim 3, wherein after the annealing step, the wire rod is surface coated with at least one member selected from the group consisting of MgO, Al ₂ O ₃ , ZnO, and ZrO ₂ .