JP3505048B2 - High strength steel wire for high strength ACSR with low iron loss in high magnetic field - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel stranded wire (A) used to reinforce an Al conductor wire of a cable for a transmission line.
It relates to CSR (Aluminium Conductor Steel Reinforced) steel wire.

[0002]

2. Description of the Related Art ACSR, a US company, devised the ACSR.
Due to the light weight of Al, it is often used as a power transmission line. However, since Al has low strength, it is used in combination with a steel wire plated with Zn or Al at the center of the ACSR for reinforcement.
Usually, JIS SWRH62-77A is used for the said steel wire as an element wire, and the steel wire after cold drawing is twisted and used for 3-19 pieces. Such a core wire has strength, elongation, twist value,
Although there are regulations regarding breakage during wrapping tests, AC
There is no specific regulation on iron loss when used as SR. However, in the actual steel core wire for ACSR,
Since a current flows through the hard Al wire, which is matched with the circumference of the steel stranded wire, there is a drawback that iron loss occurs due to the induced current. Although this iron loss causes a large transmission loss, at present, no measures are taken to prevent this iron loss.

Generally, electromagnetic steel sheets are used to reduce iron loss of transformers and motors. Grain-oriented electrical steel sheets in which crystal orientations are aligned with the rolling direction, non-oriented electrical steel sheets in which crystal orientations are randomly arranged. It has been known. In these electromagnetic steel sheets, steel containing C is used in the manufacturing process in order to control the crystal orientation, and in the final product, C is obtained by decarburization annealing or the like.
To 30ppm or less. This method requires a large manufacturing cost. Further, these are all related to thin plates, and there is no report on a method of reducing iron loss when a stranded wire is twisted with a surrounding hard Al wire.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a steel core wire for ACSR capable of reducing iron loss during power transmission by specifying the component system of steel wire and manufacturing conditions, and a manufacturing method thereof. .

[0005]

In order to solve such a problem, the present invention makes it possible to reduce the power loss during power transmission by limiting the composition of the steel material and selecting the manufacturing conditions of the steel material. The present invention provides a steel core wire for ACSR and a manufacturing method thereof. That is, the main points are as follows.

(1) C: 0.01% to 0.
3%, Si: 0.6% to 6.5%, Mn: 0.10% to
1.5%, and the relation between C and Si is Si ≧ 10 × C +
High strength A with low iron loss in a high magnetic field, characterized by being in the range of 0.5 and the balance being Fe and unavoidable impurities
Steel wire for CSR.

(2) Al: 0.002% by weight
The steel wire for high strength ACSR having a high magnetic field and a low iron loss according to (1), which contains 0.050%. (3) wt%, Nb: 0.002% to 0.10%, T
i: 0.002% to 0.10% of one kind or two or more kinds contained in (1) to (2). Steel wire for ACSR.

(4) In weight%, Cu: 0.02% to 0.5%, Ni: 0.02% to 0.5%, Cr: 0.02% to 0.5%, Mo: 0. 02% to 0.5%, Co: 0.02% to 0.5%, W: 0.02% to 0.5%, or one or more of (1) to. The high-strength steel wire for ACSR having a high magnetic field and low iron loss according to any one of (3).

(5) V: 0.002% to 0.
High strength ACS with low iron loss in a high magnetic field according to any one of (1) to (4), characterized by containing 10%.
Steel wire for R. (6) B: 0.0002% to 0.0025% by weight
A steel wire for high strength ACSR with high magnetic field and low iron loss according to any one of (1) to (5), characterized in that

(7) Rem: 0.002% by weight%
0.10%, Ca: 0.0003% to 0.0030%,
Mg: 0.0003 to 0.01% of one kind or two or more kinds is contained, and the high strength ACSR having a low magnetic field and a low iron loss according to any one of (1) to (6). Steel wire for use.

(8) Steel wire is Zn-plated, or Al: 2 to 12%, Si: 0.01 to 0.12% in weight ratio, and the rest is hot-dipped using an alloy bath containing Zn and inevitable impurities. High strength ACS with low iron loss in a high magnetic field according to any one of (1) to (7), characterized in that
Plated steel wire for R.

(9) The total area reduction rate of the steel wire after plating is 20 to 8
A high-strength plated steel wire for ACSR with a low magnetic field and a low iron loss, which is drawn at 0%. (10) The plated steel wire for high strength ACSR with high magnetic field and low iron loss according to (9), wherein the drawn steel wire is subjected to bluing treatment at a temperature of 300 ° C. or higher and 370 ° C. or lower.

(11) Steel wire after drawing is 300 degrees or more 37
A high strength ACSR with a high magnetic field and a low iron loss, which is characterized in that the steel wire is heated at a temperature of 0 ° C. or less and a stress in the range of 20% to 50% of the tensile strength of the steel wire is applied during the heating. For plated steel wire. However, here, the high magnetic field means that the strength of the magnetic field is 20.
It means the case where it exceeds 00 A / m.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The technical idea that forms the basis of the present invention is as follows. Generally, iron loss can be separated into hysteresis loss and eddy current loss. The former is known to be affected by crystal orientation and steel purity. In the case of steel plate, (11
0) It is desirable that [001] orientation (so-called Goss orientation) be integrated, and the higher the purity, the better. But,
High-strength steel wire has a high strength by containing a large amount of C. Therefore, in the case of reducing C, it is necessary to take a means for strengthening that substitutes for it. Furthermore, since wire drawing develops a strong fibrous texture, it is almost impossible to obtain a crystal orientation other than the texture unique to the wire drawing material. On the other hand, the latter eddy current loss decreases as the specific resistance increases, so Si
It is known that the addition is effective. In particular, in order to reduce iron loss in a high magnetic field (when the magnetic field strength is strong and exceeds 2000 A / m), high Si is effective. However, the high Si steel has low ductility and easily breaks when actually drawn. In order to solve such problems as a whole, the present inventors have made various studies and found the following solutions.

In order to reduce the hysteresis loss, it is essential to reduce the C content. Therefore, it is necessary to compensate the decrease in strength due to the decrease in C by another method. In general, the higher the C content, the greater the increase in strength due to wire drawing.
If the amount is reduced, higher strength due to wire drawing cannot be expected so much. However, by increasing Si instead of C, it is possible to increase the amount of strength increase due to wire drawing. If Si is simply increased, wire drawing workability is hindered and the wire is easily broken during wire drawing. However, by lowering the amount of C, strength can be increased without hindering wire drawing workability, and hysteresis loss can be reduced. Can also be reduced. In order to maintain good wire drawing workability, the contents of C and Si must be within a predetermined range. Further, in order to reduce the iron loss in a high magnetic field as intended by the present invention, Si needs to be added to C in a predetermined amount or more.

The reasons for limiting the chemical composition and the metal structure will be described in detail below. First, the reasons for limiting the components of the present invention will be described. C is an element effective for strengthening the wire rod, but its content must be strictly limited in order to significantly increase iron loss. If it exceeds 0.3%, the iron loss increases remarkably, so the content is made 0.3% or less. on the other hand,
If it is less than 0.01%, the strength that actually exceeds 1500 MPa cannot be obtained, so the content range is set to 0.01% to 0.3%.

Si is effective as a deoxidizing element and increases the specific resistance to reduce the eddy current loss. If the content is less than 0.6%, the effect is small. On the other hand, if it exceeds 6.5%, the wire drawability deteriorates, so the content range is made 0.6% or more and 6.5% or less. In order to reduce iron loss in a high magnetic field exceeding 2000 A / m, Si needs to be in a range satisfying a predetermined relationship. Especially Si content is C
It is necessary to add more than the amount satisfying a predetermined relationship with the amount. The authors have found that the relationship between the contents of C and Si is
Since it has been found that iron loss in a high magnetic field is reduced when Si ≧ 10 × C + 0.5 is satisfied, C and S
The range of the content of i is set to the range of Si ≧ 10 × C + 0.5.

Mn is an element effective in strengthening the metal,
If it is less than 0.10%, a sufficient effect cannot be obtained. On the other hand, if the content exceeds 1.5%, the toughness of the deposited metal deteriorates. Both Ti and Nb function effectively in terms of grain refinement and precipitation hardening by adding a small amount, but if the addition amount is small, the effect cannot be obtained, and addition of an excessive amount increases iron loss. Therefore, the addition amount of Nb and Ti is 0.002% to 0.10% for Nb and 0.002 for Nb.
% To 0.10%.

Each of Cu, Ni, Cr, Mo and W can increase the strength of the steel, but if the addition amount is small, the effect of increasing the strength by solid solution strengthening cannot be obtained, and if an excessive amount is added, To deteriorate the ductility, the addition amount is Cu: 0.02
% -0.5%, Ni: 0.02% -0.5%, Cr:
0.02% to 0.5%, Mo: 0.02% to 0.5%,
W: Limited to the range of 0.02% to 0.5%.

V is effective in increasing the strength of the steel, but if the addition amount is small, the effect cannot be obtained, and if the addition amount is excessive, the iron loss increases, so the addition amount is 0. It is limited to the range of 0.002% to 0.10%. B is an element that improves the hardenability of steel. In the case of the present invention, the addition thereof can increase the strength of steel,
If the amount of addition is small, the hardenability does not improve, and excessive addition increases the precipitates of B and impairs ductility, so the content is made 0.0002% to 0.0025%.

Rem, Ca and Mg are effective in finely forming the metal structure by combining with S or oxygen. If a small amount is added, S remains as it is, and excessive addition causes an increase in iron loss. Therefore, Rem: 0.002% to 0.10
%, Ca: 0.0003% to 0.0030%, Mg:
It is added in the range of 0.0003% to 0.01%. Al is effective as a deoxidizing element. If the content is less than 0.002%, there is no effect, and if it exceeds 0.05%, surface defects are likely to occur, so the content is 0.002% to 0.05%.
The range is 0%.

Next, the limiting conditions of the manufacturing conditions in the present invention will be described. The steel wire of the present invention does not need to have a particular manufacturing process. That is, the steel ingot or slab smelted and cast in the normal steelmaking process is used as a starting point to perform slab rolling as required, and a steel wire is produced in the normal wire rod rolling process. There are various operating conditions in each process, but any of them is effective.

The steel wire normally used for ACSR needs to be plated with Zn or an alloy such as Al-Zn in order to impart corrosion resistance. Corrosion resistance is improved even with normal Zn plating, but better corrosion resistance is exhibited when Al is added, so the Al amount may be selected according to the severity of the operating environment. However, if the amount of Al is less than 2%, the effect of improving corrosion resistance is insufficient, and if it exceeds 12%, the melting point rises and the plating temperature increases, leading to a decrease in the strength of the steel wire. Therefore, the amount of Al in the plating bath is limited to 2% or more and 12% or less by weight. On the other hand, the reason for adding Si to the plating bath is to prevent Fe from leaching out from steel facilities and equipment such as a plating bath and to suppress the generation of dross in the plating bath. When the amount of Si added is less than 0.01%, dross occurs, and when it exceeds 0.12%, Si is not dissolved in the plating bath. Therefore, the amount added is limited to 0.01% or more and less than 0.12%.

Since strength is usually reduced by reducing the number of plating steps, a wire drawing process (afterdraw) is performed after plating to compensate for the strength. At that time, if the total area reduction rate is less than 20%, the strength is not sufficiently recovered, and if it exceeds 80%, the ductility is remarkably deteriorated. Therefore, the range of the total area reduction rate is limited to 20% or more and less than 80%. Since elongation as a product deteriorates when such wire drawing is performed, it is necessary to heat again to secure the elongation. If the heating temperature at that time is less than 300 ° C., the elongation is not sufficiently recovered, and if it exceeds 370 ° C., the plating layer is softened. Therefore, the heating temperature range is limited to 300 ° C. or more and less than 370 ° C. Further, in order to increase the strength lowered by plating, it is effective to apply stress during heating. If the load stress at that time is less than 10% of the tensile strength of the steel wire at room temperature, the strength increase is insufficient, and if it exceeds 50%, plastic deformation locally occurs and ductility deteriorates. 10% to 50% of the tensile strength of steel wire at room temperature
Limited to:

[0025]

EXAMPLES Next, the present invention will be described in detail based on examples. First, the steel wires having the components shown in Table 1 were manufactured by refining (partially vacuum melting) by a normal converter method, continuous casting (partial steel ingot method + slabbing), and wire rod rolling (hot rolling). Furthermore, the strength was adjusted by drawing to a predetermined diameter by cold drawing. After cold drawing, some of the products were subjected to plating, afterdrawing, bluing, and warm stretching under the conditions shown in Table 2. The mechanical properties and corrosion resistance magnification of these steel wires are also shown in Table 2. Here, the corrosion resistance magnification was calculated by the following formula.

[0026]

[Chemical 1]

[0027]

[Table 1]

[0028]

[Table 2]

Each of these steel wires was wound in a ring shape having a diameter of 270 mm about 6 times, and around that, a copper wire of 700 turns on the primary side and 20 turns on the secondary side was wound, and the iron loss was measured. For the measurement of iron loss, the relationship between magnetic flux density and magnetic field strength under alternating current was measured. The frequency was 50 Hz. Magnetic field strength (Hm) is 1
The iron loss was measured in the range of 000 to 4000 (A / m) and the magnetic flux density (Bm) in the range of 0.2 to 1.5 (T). Table 3 shows the measurement results of iron loss.

[0030]

[Table 3]

As shown in Table 3, the steel of the present invention has an extremely low C
Although it is steel, it has a tensile strength exceeding 1500 MPa. Furthermore, it has a relatively good elongation and can withstand the specifications of ACSR. It can be seen that the corrosion resistance can be ensured by applying the plating, but particularly when the Zn—Al plating is applied, the corrosion resistance ratio is large and the effect is remarkable.

Further, as shown in Table 3, the steel of the present invention has a low iron loss in a high magnetic field region exceeding 2000 A / m. In particular, the iron loss tends to decrease as the C content decreases and the Si content increases, but any iron loss of the steels of the present invention is halved as compared with the currently used 0.82% C steel 21. You can see that Further, the relationship between the contents of C and Si is Si
It can be seen that the comparative steels 8 and 9 which do not satisfy the range of ≧ 10 × C + 0.5 have a high iron loss in a high magnetic field. When the heat treatment temperature after plating exceeds 400 ° C., 11, the strength, elongation, and corrosion resistance are all deteriorated. Load stress during heat treatment is 6
When it is as high as 0% σy, No. 12 is elongated and the corrosion resistance magnification is deteriorated. When the area reduction rate after plating is 81%, which is excessive, the elongation of 15 and 18 deteriorates.

[0033]

INDUSTRIAL APPLICABILITY As described above, the present invention has a high strength of 1500 MPa or more, is excellent in elongation and corrosion resistance, and has a lower iron loss in a much higher magnetic field than conventional steels. This makes it possible to significantly reduce power loss when used as the core wire of ACSR, and bring about a great effect on energy saving.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Ohba 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Stock company, Kimitsu Works (58) Fields investigated (Int.Cl. ⁷ , DB name) C22C 38 / 00-38/60

Claims (11)

(57) [Claims] 1. By weight%, C: 0.01% to 0.3%, Si: 0.6% to 6.5%, Mn: 0.10% to 1.5%, and C and Si. A steel wire for high strength ACSR having a high magnetic field and a low iron loss, characterized in that the relationship is in the range of Si ≧ 10 × C + 0.5, and the balance is Fe and unavoidable impurities. 2. Al: 0.002% to 0.0 by weight.
The steel wire for ACSR having a high magnetic field and a low iron loss according to claim 1, wherein the steel wire contains 50%. 3. Nb: 0.002% to 0.1% by weight.
0%, Ti: 0.002% to 0.10%, one or two
3. A high strength A with a low magnetic field and a low iron loss according to any one of claims 1 to 2, characterized in that it contains at least one species.
Steel wire for CSR. 4. By weight%, Cu: 0.02% to 0.5%, Ni: 0.02% to 0.5%, Cr: 0.02% to 0.5%, Mo: 0.02. % To 0.5%, Co: 0.02% to 0.5%, W: 0.02% to 0.5%, and one or more kinds are contained. Item 5. A high-strength ASR steel wire having a high magnetic field and a low iron loss according to any one of items 3. 5. V: 0.002% to 0.10.
%, High strength ACS with low iron loss and high magnetic field according to any one of claims 1 to 4.
Steel wire for R. 6. B: 0.0002% to 0.0 by weight.
025% is contained, The high strength steel wire for ACSR with a low iron loss with a high magnetic field of any one of Claim 1 thru | or 5 characterized by the above-mentioned. 7. In% by weight, Rem: 0.002% to 0.10%, Ca: 0.000
3% -0.0030%, Mg: 0.0003-0.01% 1 type (s) or 2 or more types are contained, The high magnetic field of any one of Claim 1 thru | or 6 characterized by the above-mentioned. High strength steel wire for ACSR with low iron loss. 8. A steel wire is plated with Zn, or by weight, Al: 2 to 12%, Si: 0.01 to 0.12%, and the rest is hot-dipped by using an alloy bath containing Zn and inevitable impurities. High strength A with low iron loss in a high magnetic field according to any one of claims 1 to 7.
Plated steel wire for CSR. 9. A steel wire after plating has a total area reduction rate of 20 to 80%.
9. The high-strength plated steel wire for high strength ACSR with low iron loss according to claim 8, which is drawn with. 10. The plated steel for high strength ACSR with high magnetic field and low iron loss according to claim 9, wherein the drawn steel wire is subjected to bluing treatment at a temperature of 300 ° C. or higher and 370 ° C. or lower. line. 11. The drawn steel wire is heated at a temperature of 300 ° C. or higher and 370 ° C. or lower, and the tensile strength of the steel wire is 20 during heating.
The high-strength plated steel wire for ACSR with low iron loss in a high magnetic field according to claim 9, wherein a stress in the range of 50% to 50% is applied.