JP2001355056A - Highly corrosion resistant plated stranded steel wire and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide highly corrosion resistant stranded steel wires excellent in workability. SOLUTION: In this highly corrosion resistant plated stranded steel wires, the confronted part of each elemental wire is composed of plating essentially consisting of Zn, and alloy plating essentially consisting of Zn is applied on the outside thereof. Alternatively, in the highly corrosion resistant plated stranded steel wires, a core wire or a stranded wire to form a core is present at the center of the stranded wires, the part confronted with the core wire or core stranded wire of an elemental wire present at the outside thereof is composed of plating essentially consisting of galvanizing, and alloy plating essentially consisting of Zn is applied on the outside thereof.

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
Conventionally, the environment in which the concrete is used is an alkaline environment, so that 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 afterdraw) is preferable in terms of strength characteristics, but the Zn-Fe alloy layer of the hot-dip Zn-plated 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. . Electrogalvanizing is not practiced because of the 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 highly corrosion-resistant plated twisted steel wire excellent in corrosion resistance by the conventional technology. An object of the present invention is to solve the problems of the conventional method and to provide a plated twisted steel wire having higher strength and higher corrosion resistance than the conventional method and a method for manufacturing the same.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the gist thereof is as follows. (1) A stranded wire made of a steel wire, a portion of each stranded wire facing each other is Zn-plated, and the outside thereof is plated with an alloy containing Zn as a main component. Highly corrosion-resistant plated twisted steel wire. (2) A stranded wire made of a steel wire, wherein a core wire or a stranded wire serving as a core is present at the center of the stranded wire, and a portion facing the core wire or the stranded wire outside the element is Z.
A highly corrosion-resistant plated twisted steel wire, which is n-plated and has an outer surface coated with an alloy plating mainly composed of Zn. (3) The alloy plating containing Zn as a main component contains Al in an amount of 0.1%.
The high corrosion resistance plated twisted steel wire according to the above (1) or (2), which is a Zn alloy containing 1 to 20%. (4) Outside the alloy plating layer containing Zn as a main component,
Any one of organic coating, inorganic coating, and organic coating
The highly corrosion-resistant plated twisted steel wire according to the above (1) to (3), wherein at least one is applied. (5) The steel wire is represented by mass%, C: 0.4 to 1.3%,
The high corrosion resistant plated twisted steel wire according to the above (1) or (2), wherein a steel wire composed of Si: 0.1 to 2.0% and Mn: 0.1 to 2.0% is used. (6) The steel wire is represented by mass%, and Cr: 0.05
-1.5%, Ni: 0.05-1.5%, V: 0.00
5 to 1.0%, Nb: 0.005 to 1.0%, Mo:
The highly corrosion-resistant plated twisted steel wire according to the above (5), wherein one or more of 0.005 to 1.0% is added. (7) The steel wire has a mass percentage of Cu: 0.05
The highly corrosion-resistant plated twisted steel wire according to the above (5) or (6), characterized by adding 1.5% or less. (8) The steel wire has a weight percentage of Al: 0.00
The high corrosion resistant plated twisted steel wire according to any one of the above (5) to (7), wherein 1 to 0.1% and B: 0.0005 to 0.1% are added. (9) The steel wire is, by weight%, further P: 0.02%
The high corrosion-resistant plated twisted steel wire according to any one of the above (5) to (8), wherein S: 0.02% or less is added. (10) Z according to any one of the above (5) to (9)
N-plated wire is drawn to a smaller diameter wire, and some of them are combined and twisted.
% Or more and 7% or less, and further subjected to an alloy plating containing Zn as a main component to obtain a plated stranded wire according to the above (1) or (2). Manufacturing method. (11) Z according to any one of the above (5) to (9)
N-plated wire is drawn to a smaller diameter wire, and some of them are combined and twisted, then 1%
Stretching at least 7% or less, and further applying an alloy plating containing Zn as a main component to obtain a stranded wire according to the above (1) or (2), and then applying a resin coating. Manufacturing method of high corrosion resistant plated twisted steel wire.

[0008]

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%.

[0009] Si is an element necessary for deoxidizing steel, and if its content is too small, the deoxidizing effect becomes insufficient, so that 0.1% or more is added. Further, Si forms a solid solution with the ferrite phase in the pearlite formed after the heat treatment and increases the strength after patenting, but on the other hand, it impairs the heat treatment property, so that 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.

[0010] Since Cr has the effect of increasing the strength of steel, it is added in an amount of 0.05% or more at which the effect is exhibited.
The upper limit is 1.5% or less which does not cause ductility of the steel wire. Ni has the effect of increasing the strength of steel. When adding Ni, 0.05% or more which has the effect of adding Ni is added. However, the addition of a large amount lowers the ductility.
5% or less.

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

Cu is added to improve corrosion resistance and corrosion fatigue characteristics. When adding Cu, 0.05% which has the addition effect is added. However, if a large amount is added, it becomes easy to become brittle during hot rolling.
%. Al improves the iris after patenting the γ particle size when austenitized. When adding Al, it is added in an amount of 0.001% or more at which the effect is exhibited. 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 particle size when austenitized. This effect improves ductility such as drawing. Therefore, when B is added, 0.0005% or more, which has the effect, is added. But 0.1%
If added in excess of, the transformation time for transformation by heat treatment becomes too long, so the upper limit is made 0.1%. In addition, as for P and S, the content of S is set to 0.02% or less in order to secure ductility similarly to the conventional ultrafine steel wire.
In the same manner as above, the content of the wire is impaired, so that its content is set to 0.02.
% Is desirable.

Alloy plating of Zn-10% Al or the like is performed using Zn.
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. If alloy plating or the like is performed after drawing, the amount of adhesion can be maintained, but since the steel wire having a soft plating layer is twisted, the relaxation characteristics of the strand after the stranded wire processing is reduced. Therefore, the present inventors focused on two-bath plating,
First, a method of performing Zn plating, drawing, twisting, stretching, and then plating with Zn as a main component was created.

The reason why Zn plating is performed first is that Zn plating can be performed relatively easily. Here, 3% or less of Al, Si, Ti, Mn, Mg, REM is used for Zn plating.
A material including the like can be used. Next, the wire drawing may be performed in any amount as long as the wire can be drawn so that the Zn plating does not peel off. Further, the drawn wire is subjected to stranded wire processing according to the purpose to obtain a stranded wire. The stranded wire is stretched. If the stranded wire is immersed in the molten Zn alloy plating without 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.
The subsequent Zn alloy plating is performed at a temperature of 450 ° C. or higher and a temperature higher than a general aging temperature (bluing temperature). However, since the time required for the plating process can be as short as 10 seconds or less, the strength decreases. Adjust so that does not increase.

Further, since the Zn plating is applied before the wire drawing, the alloy plating can be applied after the twisting without any particular pretreatment. As a result, in the plated stranded wire obtained, the portion where the plated steel wires are twisted as shown in FIG. 1 is plated mainly with Zn, and the outer periphery thereof is plated with Zn alloy. In addition, as a Zn alloy plating, a zinc alloy containing 0.1 to 20% of Al is disclosed.
One or more of Mg, Si, Sn, and REM may be added in addition to Al as disclosed in JP-A-302684 to further increase the corrosion resistance.

Although the present invention combines stretching and bluing, the same effect can be obtained by performing heat stretching in a plating bath. In addition, after applying heat stretching to the alloy-plated PC strand, the resin coating is performed to further improve the corrosion resistance. 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.

[0019]

EXAMPLES The effects of the present invention will be described below based on examples. Table 1 shows the chemical components of the test steel used for the trial production. The test steels A-1 to A-4 are all chemical components of the steel of the present invention. In methods 1 to 4 of the present invention, steels A-1 to A-4 were 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 obtained by wire rolling, and was directly immersed in a molten salt and subjected to a patenting treatment.
After pickling this wire, it was thinly galvanized. Thereafter, wire drawing from 11 mm to 4.2 mm was performed. Thereafter, stranded wire processing was performed to obtain a seven-stranded PC steel stranded wire having a diameter of 12.7 mm. Furthermore, after performing 2 to 6% stretching, alloy plating was performed using a Zn-10% Al Zn alloy bath.

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, 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 pickling this wire, it was drawn to a diameter of 7 mm, and then subjected to Zn-10% Al alloy plating by a two-bath method. Thereafter, wire drawing from 7 mm to 4.2 mm was performed. Thereafter, 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 2371
The salt spray test was performed for 500 hours in accordance with the above to investigate corrosion 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 the result is that the adhesion amount of plating is small.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

According to the present invention, a plated stranded wire having high corrosion resistance and excellent relaxation characteristics can be obtained.

[Brief description of the drawings]

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

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

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C23C 2/02 C23C 2/02 2/06 2/06 2/26 2/26 (72) Inventor Hajime Ishikawa Kimitsu, Chiba Prefecture 1 Kimitsu-shi, Nippon Steel Corporation Kimitsu Works F-term (reference) 4E096 EA26 EA27 4K027 AA06 AA23 AB05 AB26 AB44 AC18 AC82 AC87

Claims (11)

[Claims] 1. A stranded wire made of a steel wire, in which a portion of each strand of the stranded wire opposite to the strand is Zn-plated, and an outer portion of the stranded wire is plated with an alloy containing Zn as a main component. High corrosion resistance plated twisted steel wire characterized by being made. 2. A stranded wire made of a steel wire, wherein a core wire or a stranded wire serving as a core is present at the center of the stranded wire, and a portion of the stranded wire facing the core wire or the stranded wire outside the stranded wire is provided. A highly corrosion-resistant plated twisted steel wire, which is Zn-plated and has an outer surface coated with an alloy plating containing Zn as a main component. 3. The method according to claim 1, wherein the alloy plating mainly containing Zn is A
The high corrosion resistant plated twisted steel wire according to claim 1 or 2, which is a Zn alloy containing 0.1 to 20% of l. 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 containing Zn as a main component.
High corrosion resistance plated twisted steel wire. 5. The steel wire according to claim 1, wherein C: 0.4 to
1.3%, Si: 0.1 to 2.0%, Mn: 0.1 to
3. A highly corrosion-resistant plated twisted steel wire according to claim 1 or 2, wherein a steel wire consisting of 2.0% is used. 6. The steel wire 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 one or more of Mo: 0.005 to 1.0% are added. 7. The steel wire according to claim 1, further comprising:
The high corrosion-resistant plated twisted steel wire according to claim 5 or 6, wherein 0.05 to 1.5% is added. 8. The steel wire according to claim 1, further comprising:
The highly corrosion-resistant plated twisted steel wire according to any one of claims 5 to 7, wherein 0.001 to 0.1% and B: 0.0005 to 0.1% are added. 9. The steel wire according to claim 1, further comprising:
The high corrosion resistant plated twisted steel wire according to any one of claims 5 to 8, wherein 0.02% or less and S: 0.02% or less are added. 10. The Zn-plated wire according to any one of claims 5 to 9, which is drawn into a wire having a smaller diameter, and after twisting by combining some of the wires.
Perform stretching of 1% or more and 7% or less, and further Zn
3. A method for producing a highly corrosion-resistant plated twisted steel wire, characterized in that the plated twisted wire according to claim 1 or 2 is formed by applying an alloy plating mainly comprising: 11. The Zn-plated wire according to any one of claims 5 to 9, which is drawn to a wire having a smaller diameter, and a wire having a smaller diameter is combined and twisted.
% By applying an alloy plating containing Zn as a main component to obtain a stranded wire according to claim 1 or 2, followed by applying a resin coating thereto. Manufacturing method of plated twisted steel wire.