JP2002317388A - Plated strand steel wire having high corrosion resistance and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strand steel wire having excellent workability and high corrosion resistance and a method for producing the wire. SOLUTION: The plated strand wire having high corrosion resistance is a stranded steel wire having a thick plated layer at the outer circumference of the stranded wire compared with the thickness of the plated layer at the part contacting the element wires with each other. The difference of the plated layer thickness is >=3 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip galvanized wire, a rope, a hot-rolled wire formed by drawing a wire having a smaller diameter by wire drawing and twisting a plurality of the wires. The present invention relates to a twisted steel wire such as an ACSR wire or a PC steel twisted wire.

[0002]

2. Description of the Related Art PC steel wire is generally JIS G3502.
Is manufactured by performing a patenting process on a piano wire specified in (1), drawing the wire, and then performing hot stretching in a temperature range of 300 to 400 ° C. PC steel wire
Since concrete, which is an environment in which it is used, is an alkaline environment, there has been little problem with corrosion resistance. However, in recent years, river sand and mountain sand, which are aggregates of concrete, are insufficient, and sea sand has been used instead. Therefore, the case where corrosion resistance is required also for PC steel wire is increasing. In addition, the number of cases where the PC stranded wire itself is used not as concrete but as an external cable is increasing, and improvement in corrosion resistance is expected.

For this reason, Japanese Patent Application Laid-Open No. Sho 59-179755 discloses that the steel composition is controlled, specifically, Cu, Ni,
It is described that by adding W to reduce the Si content, corrosion of PC steel wires in a salt environment is suppressed. However, keeping the Si content low is contrary to increasing the strength of the PC steel wire and lowering the relaxation value.

[0004] On the other hand, coating such as plating on a PC steel wire is rarely performed. This is because when hot-dip Zn plating is performed, the steel wire temperature rises to about 450 ° C., and the relaxation value increases. Further, a method of drawing after hot-dip Zn plating (so-called afterdrawing) is preferable in terms of strength characteristics, but the Zn—Fe alloy layer of the hot-dip Zn-coated steel wire is brittle, and cracks occur in the plated layer during drawing. In addition, the drawn Zn layer becomes relatively thin by the drawing process, so that it is necessary to perform thick plating before the drawing in order to have sufficient corrosion resistance. However, when the plating thickness is large, there is a problem that the wire drawing becomes extremely difficult.

On the other hand, in order to improve the corrosion resistance of steel wires,
Various Zn-Al alloy platings have been developed in place of conventional Zn plating. For example, Japanese Patent Publication No. 55-26702
JP-A No. 54-33223, Zn-Al-Mg, JP-A-57-500475, Zn-Al-mish metal, JP-A-56-1.
No. 12452 describes Zn-Al-Na and the like. Since these are all plated by a method of immersing a steel wire in an alloy plating bath in a molten state (about 450 ° C.), similarly to the conventional hot-dip Zn plating method, there is the same problem as the hot-dip Zn plating described above. . The electrogalvanizing method has not been implemented because of its high cost and the risk of delayed destruction due to the intrusion of hydrogen.

[0006]

As described above, it has not been possible to produce a high-corrosion-resistant plated wire having excellent corrosion resistance by the conventional technology. An object of the present invention is to solve the problems of the above-mentioned conventional method and to provide a twisted plated steel wire having higher strength and higher corrosion resistance than before and a method for manufacturing the same.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and the gist thereof is as follows. (1) A highly corrosion resistant plated twisted steel wire, which is a steel twisted wire, wherein the plating thickness of the outer periphery of the twisted wire is thicker than the plating thickness of the portion where the strand came into contact.

(2) The plating is Zn plating, Zn-
The high corrosion resistant plated twisted steel wire according to the above (1), which is one of an Al-based alloy plating and an Al plating. (3) The high corrosion resistant plated twisted steel according to (1) or (2), wherein a difference in plating thickness between an adjacent portion of the strand and an outer peripheral portion of the stranded wire is at least 3 μm or more. line.

(4) Any one of the above (1) to (3), wherein at least one of an organic coating, an inorganic coating and an organic coating is applied to the outside of the alloy plating layer. High corrosion resistance plated twisted steel wire according to item. (5) The composition of the steel is expressed in mass%, C: 0.4 to 1.3.
%, Si: 0.1 to 2.0%, Mn: 0.1 to 2.0%
The highly corrosion-resistant plated twisted steel wire according to any one of the above (1) to (4), wherein the steel wire comprises:

(6) The steel is, in mass%,
r: 0.05 to 1.5%, Ni: 0.05 to 1.5%,
V: 0.005 to 1.0%, Nb: 0.005 to 1.0
%, Mo: steel containing at least one or more of 0.005 to 1.0%. (7) The steel, in terms of mass%, further contains Cu: 0.05 to
The highly corrosion-resistant plated twisted steel wire according to the above (5) or (6), which is a steel containing 1.5%.

(8) The steel contains, by mass%,
l: 0.001-0.1%, B: 0.0005-0.1
(5) to (7), wherein the steel contains
The highly corrosion-resistant plated twisted steel wire according to any one of the above items. (9) The steel according to any one of the above (5) to (8), wherein the steel is a steel whose mass% is further restricted to P: 0.02% or less and S: 0.02% or less. High corrosion resistance plated twisted steel wire according to the item.

(10) A zinc-plated steel material comprising the steel component according to any one of the above items 5 to 9 is drawn to a wire having a smaller diameter, and several wires are combined and twisted. After the combination, stretching of 1% or more and 7% or less is performed, and further, an alloy plating containing Zn as a main component is performed to obtain a plated twisted steel wire according to the above (1) or (2). Method of producing high corrosion resistant plated twisted steel wire.

(11) A galvanized steel material comprising the steel component according to any one of the above (5) to (9),
After drawing a wire with a smaller diameter, combining and twisting some of the wires, performing stretching of 1% or more and 7% or less, and further applying an alloy plating containing Zn as a main component, The method for producing a highly corrosion-resistant plated twisted steel wire according to the above (4), which comprises resin coating.

[0014]

First, the reasons for limiting the steel composition will be described. All components are% by weight. C is an element effective for strengthening, and in order to obtain a high-strength steel wire, the amount of C is set to 0.7.
However, if the content is too high, proeutectoid cementite is likely to be precipitated, so that ductility is reduced and wire drawability is deteriorated. Therefore, the upper limit is set to 1.3%.

Si is an element necessary for deoxidizing steel, and therefore, when its content is too small, the deoxidizing effect becomes insufficient. Therefore, Si is added in an amount of 0.1% or more. In addition, Si
Is dissolved in the ferrite phase in the pearlite formed after the heat treatment and increases the strength after patenting, but on the other hand, the heat treatment property is impaired, so the content is 2.0% or less. As for Mn, 0.1% or more of Mn is added to secure the hardenability of steel. However, the addition of a large amount of Mn makes the transformation time during patenting too long, so it is set to 2.0 or less.

Cr is added to increase the strength of steel. When added, the effect is exhibited 0.05
% Or more without causing ductility of steel wire
5% or less. Ni has the effect of increasing the strength of steel. When it is added, it is added in an amount of 0.05% or more that has the effect. However, if the added amount is too large, the ductility is reduced.

V has the effect of increasing the strength of steel. When it is added, it is added in an amount of 0.005% or more that has the effect. However, if the amount of addition is too large, the ductility decreases, so the upper limit is made 1.0%. Nb has the effect of increasing the strength of steel. When it is added, it has an effect of addition.
Add 005% or more. However, if the amount of addition is too large, the ductility decreases, so the upper limit is made 1.0%.

Cu is added to improve corrosion resistance and corrosion fatigue characteristics. When adding, 0.05% which has the effect of the addition is added. However, if a large amount is added, it is likely to become brittle during hot rolling, so the upper limit is made 1.5%. Al improves the iris after patenting the γ particle size when austenitized. When Al is added, 0.001% or more at which the effect is exerted is added.
However, since the addition of a large amount increases the amount of inclusions, the upper limit is set to 0.1%.

B also has the effect of reducing the γ grain size when austenitized. Thereby, ductility such as drawing is improved. Therefore, when added, it has the effect,
Add 0.0005% or more. However, if the addition exceeds 0.1%, the transformation time for transformation by heat treatment becomes too long, so the upper limit is made 0.1%. As in the case of the conventional ultrafine steel wire, the content of S is set to 0.0 to secure ductility.
P is set to 2% or less, and P also impairs the ductility of the wire similarly to S, so its content is preferably set to 0.02% or less.

Alloy plating of Zn-10% Al or the like
Excellent in corrosion resistance compared to. However, Zn-
When wire drawing is performed by applying a 10% Al alloy or the like, the amount of adhesion is relatively reduced by the wire drawing. In addition, if alloy plating is performed after drawing, the amount of adhesion can be maintained,
Since the steel wire having the soft plating layer is twisted, the relaxation property of the strand after the stranded wire processing is reduced. Therefore, the present inventors have devised a method in which the same plating as the plating performed before the wire drawing is performed again after the stranded wire processing.

First, the plating for wire drawing is made of Zn,
Any plating such as Zn-5% Al, Zn-10% Al, and Al can be used as long as it can be drawn without any problem. The plating method may be either hot-dip plating or electroplating. Further, the above-mentioned Zn plating is performed on Al, Si, T of 3% or less.
A material containing i, Mn, Mg, REM, or the like can be used. The amount of wire drawing may be any amount as long as the wire can be drawn to such an extent that the plating applied first does not peel off. Next, the drawn wire is subjected to stranded wire processing according to the purpose to obtain a stranded wire. The stranded wire is stretched. When hot-dip plating is applied to a stranded wire without performing stretching, the stranded wire is heated and the relaxation characteristics are reduced. In order to suppress the deterioration of the relaxation characteristics, strain age hardening is used. Therefore, stretching is performed in advance. If the stretching is less than 1%, the strain age hardening is small, and even if the stretching exceeds 7%, the increase in the yield strength is saturated. Subsequent hot-dip plating is 45 mm for Zn.
Although the temperature is 0 ° C. or higher and higher than the general aging temperature (bluing temperature), the time required for the plating treatment can be as short as 10 seconds or less.

Further, since plating is performed before wire drawing, hot-dip plating can be performed after twisting without particularly requiring pretreatment. As a result, as shown in FIG. 1, the resulting plated stranded wire has a thin portion where the plated steel wires are twisted and a thick outer periphery. Although the present invention combines stretching and bluing, the same effect can be obtained by performing heat stretching in a hot-dip plating bath.

Further, by subjecting the alloy-plated PC strand to heat stretching and then coating it with a resin, the corrosion resistance can be further improved. The resin coating may be any of polyethylene, epoxy, polyurethane, polypropylene, organic paints, and inorganic paints, and must be used properly depending on the required environment.

[0024]

EXAMPLES The effects of the present invention will be described based on the following examples. Table 1 shows the chemical components of the test steel used for the trial production. Table 1
Was melted and cast by continuous casting, and then hot-rolled into billets. After the billet was reheated, a wire rod having a diameter of 11 mm was formed by wire rolling, and was directly immersed in molten salt to perform a patenting treatment. After pickling this wire, Zn
A -10% Al plating process was performed. Thereafter, wire drawing from 11 mm to 4.2 mm was performed. Thereafter, stranded wire processing was performed to obtain a seven-stranded wire. Thereafter, after performing stretching of 2 to 6%, the same plating treatment as shown in Table 2 was performed as in the previously applied plating. Table 2 shows the results.

In Comparative Method 1, a steel of A-1 was cast by continuous casting, and then hot-rolled into a billet. After the billet was reheated, a wire rod having a diameter of 11 mm was formed by wire rolling, and was directly immersed in molten salt to perform a patenting treatment. After this wire was pickled, wire drawing from 11 mm to 4.2 mm was performed. Thereafter, Zn-10% Al alloy plating was performed by a two-bath method. Thereafter, hot stretching was performed.

In Comparative Method 2, the steel A-1 was cast by continuous casting, and then billeted by hot rolling. After the billet was reheated, a wire rod having a diameter of 11 mm was formed by wire rolling, and was directly immersed in molten salt to perform a patenting treatment. After this wire was pickled, it was plated with Zn-10% Al alloy. Thereafter, wire drawing from 11 mm to 4.2 mm was performed, and then hot stretching was performed.

Using these stranded wires, the coating weight,
The corrosion weight loss and relaxation value after 500 hours of salt spray were measured. At this time, the relaxation characteristics were investigated according to JIS G 3536, and JIS Z 237 was used.
According to No. 1, a salt spray test for 500 hours was performed to investigate corrosion weight loss. According to the method of the present invention, a large amount of plating can be obtained, resulting in excellent corrosion resistance and excellent relaxation properties. On the other hand, in Comparative method 1, although the amount of adhesion is large, the relaxation characteristics are deteriorated. Comparative method 2 has a relaxation property lower than that of the method of the present invention, and a smaller amount of plating adhered.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

According to the present invention, a highly corrosion-resistant plated stranded wire can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (two twists) of a plated stranded wire according to the present invention.

FIG. 2 is a cross-sectional view (7 strands) of a plated stranded wire according to the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C23C 28/00 C23C 28/00 AB C25D 5/26 C25D 5/26 C 7/06 7/06 U D07B 1/16 D07B 1/16 // C23C 2/06 C23C 2/06 2/12 2/12 2/38 2/38 (72) Inventor Hajime Ishikawa 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu F term in the steelworks (reference) 3B153 AA02 AA09 AA45 AA47 BB15 CC13 CC26 CC27 CC41 CC52 EE15 EE16 FF02 GG07 4K024 AA05 AB02 AB06 AB16 BA02 BC03 DB06 DB07 GA04 4K027 AA02 AA06 AA22 AA23 AB04 AC42 AB04 AB42 AB04 BA21 BB01 BB03 BC02 CA11 CA18 CA53 CA67

Claims (11)

[Claims] Claims: 1. A highly corrosion-resistant stranded steel wire, wherein a stranded wire of a steel wire has a larger plating thickness on an outer periphery of the stranded wire than a plating thickness of a portion where the element wire contacts. . 2. The method according to claim 1, wherein the plating is Zn plating, Zn-Al
2. The highly corrosion-resistant plated twisted steel wire according to claim 1, wherein the wire is one of a system alloy plating and an Al plating. 3. The high corrosion resistant plated twisted steel wire according to claim 1, wherein a difference in plating thickness between an adjacent portion of the strand and an outer peripheral portion of the stranded wire is at least 3 μm or more. . 4. The method according to claim 1, wherein at least one of an organic coating, an inorganic coating, and an organic coating is applied to the outside of the alloy plating layer. High corrosion resistant plated twisted steel wire. 5. The steel composition according to claim 1, wherein C is 0.4% by mass.
1.3%, Si: 0.1-2.0%, Mn: 0.1-
The steel containing 2.0%.
The highly corrosion-resistant plated twisted steel wire according to any one of the above items. 6. The steel according to claim 1, further comprising:
0.05-1.5%, Ni: 0.05-1.5%, V:
0.005 to 1.0%, Nb: 0.005 to 1.0%,
The high corrosion resistant plated twisted steel wire according to claim 5, wherein the steel is a steel containing at least one kind of Mo: 0.005 to 1.0%. 7. The steel according to claim 1, further comprising:
The highly corrosion-resistant plated twisted steel wire according to claim 5 or 6, wherein the steel wire contains 0.05 to 1.5%. 8. The steel according to claim 1, further comprising:
The highly corrosion-resistant plated twisted steel wire according to any one of claims 5 to 7, wherein the steel is a steel containing 0.001 to 0.1% and B: 0.0005 to 0.1%. 9. The steel according to claim 1, further comprising:
The highly corrosion resistant plated twisted steel wire according to any one of claims 5 to 8, wherein the steel is regulated to not more than 02% and S: not more than 0.02%. 10. A steel material comprising the steel component according to any one of claims 5 to 9, and galvanized steel material is drawn to a wire having a smaller diameter, and some of the wires are combined and twisted. After being combined, stretch of 1% or more and 7% or less is performed, and further, an alloy plating containing Zn as a main component is applied to obtain a plated twisted steel wire according to claim 1 or 2, characterized by high corrosion resistance. Manufacturing method of plated twisted steel wire. 11. A galvanized steel material comprising the steel component according to any one of claims 5 to 9 is drawn to a wire having a smaller diameter, and some of the wires are combined and twisted. 5. The high corrosion resistant plated twisted steel wire according to claim 4, wherein after stretching, 1% or more and 7% or less stretching is performed, and further, an alloy plating containing Zn as a main component is performed, and then resin coating is performed. Manufacturing method.