JP2675447B2 - High strength and corrosion resistant composite wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength, high-corrosion-resistant composite wire suitable for use in applications exposed to salt water, such as a rope wire for seawater resistance.

[0002]

2. Description of the Related Art Since Ti has an advantage in that it has excellent corrosion resistance, recently, the Ti wire is being used for applications requiring corrosion resistance such as rope element wires. However, pure Ti
Since the strength of the wire is as small as 100 kgf / mm ² or less, the strength is insufficient as a structural material. For this reason, a means for increasing the strength by adding elements such as Al and V to Ti has been adopted, but the addition of such elements such as Al and V has the drawback of lowering the workability. Therefore, a composite wire has been proposed in which a steel wire having high strength and high hardness is used as a core wire, and the peripheral surface of the steel wire is coated with Ti by hot working to satisfy both corrosion resistance and strength.

This composite wire can reduce the amount of expensive Ti used, and can significantly reduce the material cost.

[0004]

However, although this conventional composite wire has the advantages of both the high strength possessed by the steel core wire and the high corrosion resistance possessed by the Ti layer of the coating layer, Since a hard and brittle compound layer is formed between the steel wire and the Ti layer, there is a drawback that the bonding strength is low.
Therefore, the conventional composite wire has not been able to effectively exhibit the excellent characteristics of each constituent element.

In practice, when this conventional composite wire is used for a rope element wire, the Ti coating layer is peeled off due to deformation such as twisting and bending when forming the rope in the manufacturing process. There is. If the peeled portion is mixed in the product, corrosion locally progresses. Further, in the process of using the composite wire, when the stress due to the vibration is applied to the composite wire, the Ti coating layer is gradually separated. in this way,
In the case of a wire, unlike the case of a plate, the joint strength between the core material and the covering material and the toughness of the joint have a significant influence on the durability.

The present invention has been made in view of the above problems, and an intermetallic compound is not substantially present between Ti or a Ti alloy and steel, and extremely high joint strength and joint toughness are obtained. An object of the present invention is to provide a high-strength and high-corrosion-resistant composite wire that can be manufactured.

[0007]

A high-strength and high-corrosion-resistant composite wire according to the present invention comprises a steel core wire containing 3 to 50% by weight of Ni and a Ti or Ti alloy coating layer bonded by cold drawing and heat treatment. It is characterized in that there is substantially no intermetallic compound at the interface between the two.

Another high strength and high corrosion resistance composite wire according to the present invention is a steel core wire containing 3 to 50% by weight of Ni and a T core wire.
The i or Ti alloy coating layer is joined by cold drawing and heat treatment at a temperature of less than 600 ° C.

Further, between the steel core wire and the coating layer,
A Ni or Ni alloy layer may be arranged.

Further, when the thickness of the coating layer is set to a coverage ratio of 20% or less in terms of sectional area ratio, N in the steel core wire is
Sufficient bonding strength can be obtained regardless of the i content.

[0011]

The present inventor has noticed that the formation of an intermetallic compound between the Ti or Ti alloy coating layer and the steel core wire is a factor that reduces the joint strength between the two. Various experimental studies were carried out to join the two without producing the compound. As a result, it was found that the coating layer and the core wire can be joined without generating an intermetallic compound by alternately performing cold wire drawing and heat treatment instead of the conventional hot working. .

Generally, the bonding of different kinds of materials is performed by forming a diffusion layer, by forming a compound layer, or by forming an atomic force without forming the diffusion layer and the compound layer. In the former two cases, since a heterogeneous phase exists at the interface, the stress distribution at the time of deformation becomes complicated, and in particular, when this heterogeneous phase is more brittle than the coating layer, it becomes a starting point of fracture. Therefore, it is not preferable to bond different materials by forming the diffusion layer or the compound layer. On the other hand, the joining by the third atomic force can be performed by cold working. The joining by the atomic force does not have the above-mentioned inconvenience, and the deterioration of the characteristics at the interface is small.

Therefore, as in the present invention, by joining the coating layer and the core wire by cold working, it is possible to prevent the formation of an intermetallic compound, and to prevent peeling or the like at the interface between the coating layer and the core wire. You can get the line. Note that this cold working means working at a temperature at which an intermetallic compound does not occur at the interface, and the heat treatment inserted during this cold working is performed auxiliary to improve the joint strength. is there.

In the present invention, the absence of the intermetallic compound means that the amount of the intermetallic compound is such that characteristic deterioration occurs when the structure of the composite wire is observed at an optical microscope observation level of less than 1000 times. It means that the existence of is not substantially recognized.

Further, as described above, in the high strength and corrosion resistant composite wire according to the present invention, the steel core wire and the Ti or Ti alloy coating layer are formed by alternately performing cold drawing and heat treatment at least once. Although joined, this heat treatment
By carrying out at a temperature lower than 600 ° C., it is possible to reliably prevent the formation of intermetallic compounds between the Ti or Ti alloy coating layer and the steel core wire.

The quality of joining is also affected by the material of the steel wire. In particular, when the covering rate of the covering material is high, the pressure in the direction perpendicular to the interface is reduced and the slip deformation at the interface is reduced during the wire drawing process that becomes the driving force for joining.
Originally, due to this slip deformation, a clean new surface is generated between the Ti or Ti alloy coating layer and the steel wire core wire, and the new surfaces are brought into contact with each other by the pressure in the vertical direction and bonded by the atomic force. . For this reason, the decrease in pressure and the decrease in slip deformation mean that sufficient bonding strength cannot be obtained.

However, when the core steel wire containing Ni in an amount of 3% by weight or more is used as in the present invention,
The bonding strength between the steel wire and the coating layer can be increased, and sufficient bonding strength can be obtained even when the coverage is high. However, if the Ni content exceeds 50% by weight, on the contrary, the strength of the steel wire decreases, and the amount of expensive Ni increases, so that the manufacturing cost increases. Therefore, Ni
The content is preferably 50% by weight or less.

On the other hand, the coverage of the Ti or Ti alloy coating layer is
When it is as low as 20% or less, even if the Ni content of the steel wire core is less than 3% by weight, a new surface is easily generated at the interface due to wire drawing, and a high-strength joint surface can be obtained.

A Ni or Ni alloy layer may be interposed between the steel wire and the Ni or Ni alloy coating layer. Also in this case, peeling between the steel wire core wire and the coating layer can be avoided.

[0020]

EXAMPLES Next, examples of the present invention will be described.

First, the manufacturing process of the composite wire will be described. The surfaces of the steel rod and the Ti tape were continuously ground to obtain a steel rod having a diameter of 9.5 mm and a Ti tape having a thickness of 0.4 mm. Then, Ti tape is vertically attached to the steel rod,
The widthwise ends of the tape were joined by TIG welding.
Then, in the same process, wire drawing was performed at a workability of 20% to obtain a composite wire with a diameter of 9.2 mm. This composite wire was heated at 500 ° C. for 0.5 hour to be heat-treated. Then, after wire drawing to have a diameter of 5.0 mm, heat treatment was performed under the following conditions, and a diameter of 2.
After wire drawing to 4 mm, it was further heat treated under the same conditions as the following. After that, the wire was finally drawn to a diameter of 1.5 mm.

A tensile test was performed on the obtained composite wire to measure the aperture value. Further, in this tensile test, the fracture surface was observed, and it was examined whether delamination occurred at the joint interface and whether an intermetallic compound was present at the interface. Table 1 below shows the relationship between the heat treatment temperature and the result of this tensile test.
Shown in

[0023]

[Table 1]

As is clear from Table 1, when the heat treatment temperature is 300 ° C., peeling occurs at a part of the interface. Further, when the heat treatment temperature was 600 ° C. or higher, an intermetallic compound was generated at the interface, and peeling occurred between the steel core wire and the Ti coating layer even in the tensile test. This is because the compound is brittle and cannot be integrally deformed with other parts.

If peeling does not occur, the aperture value is
It is 30% or more, and whether or not this aperture value is 30% or more is an index of the quality of the joining. This is because the higher the joint strength is, the steel core wire and the Ti or Ti alloy coating layer are integrally deformed at the time of breaking, so that the drawing becomes larger. Therefore, there is a good correlation between the bond strength and the drawing.

Next, it is considered that the bonding strength is the best.
The results of investigating the relationship between the quality of joining and the Ni content by fixing the heat treatment temperature to 0 ° C. and variously changing the Ni content in the steel core wire will be described.

Table 2 below shows the bonding wire diameter (mm) and breaking strength σ _B (kgf / mm ₂ ). However, the bonded wire diameter is the maximum wire diameter that can achieve good bonding without peeling, and the drawing is 30%.
It is the maximum diameter of the above. The breaking strength is 1.5m
It was calculated for a composite wire of m diameter. The coverage of the coating layer is 15%.

[0028]

[Table 2]

As is clear from Table 2, the Ni content is
When it is 3% or more, the bonding strength is improved, that is, the bonding wire diameter is increased. Therefore, the Ni content is preferably 3% or more. However, if the Ni addition amount exceeds 50%, the breaking strength is significantly reduced, so the Ni content is 3 to 50%.
Is preferable.

In the examples in which a Ni or Ni alloy layer was provided between the steel core wire and the Ti or Ti alloy coating layer, good joint strength was similarly obtained.

That is, a steel wire containing 3% Ni is used as a core wire, and the core wire is coated with a Ni or Ni alloy layer,
After further coating the Ti layer, the composite wire was heated at 500 ° C for 0.5 hour, and then wire-drawn to a diameter of 5.0 mm, then 400
After heating to ℃ for 1 hour, wire drawing to 2.4 mm diameter,
After heating at 0 ° C for 1 hour, the wire was finally drawn to a diameter of 1.8 mm.

As a result, as shown in Table 3 below, no interfacial compound was observed and a good aperture value was obtained.

[0033]

[Table 3]

Next, the relationship between the coverage of the Ti or Ti alloy coating layer and the bonding strength will be described with reference to examples.

72A material with a diameter of 9.5 mm (0.72% C; Mn
Fe) of 0.3% or less was used as a core wire, and this core wire was coated with Ti at various coverage ratios shown in Table 4 below, and then subjected to cold working. Then, the aperture value after processing to 1.5 mm and the aperture value when processing at 30% and then heating at 400 ° C. for 1 hour and then processing to 1.5 mm were obtained, and shown in Table 4 below. This aperture value is adopted as an index of bonding strength.

As shown in Table 4, when the coverage was 20% or less, the aperture value under all conditions was sufficiently high.

[0037]

[Table 4]

[0038]

According to the present invention, the steel core wire and Ti or Ti are used.
Since the alloy coating layer is bonded by cold drawing and heat treatment, there is substantially no intermetallic compound between them, and extremely high bonding strength can be obtained. Further, since the bonding is performed without forming the intermetallic compound phase at the interface, there is no change in the material at the interface and the followability to deformation is good.

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Claims (5)

(57) [Claims] 1. A steel core wire containing 3 to 50% by weight of Ni and a Ti or Ti alloy coating layer are joined by cold drawing and heat treatment, and an intermetallic compound is substantially present at the interface between them. High strength and corrosion resistant composite wire characterized by not 2. A steel core wire containing 3 to 50% by weight of Ni and a Ti or Ti alloy coating layer are cold drawn and 600 ° C.
A high-strength, high-corrosion-resistant composite wire, which is joined by heat treatment at a temperature of less than. 3. A steel core wire containing 3 to 50% by weight of Ni, a Ti or Ti alloy coating layer, and a Ni or Ni alloy layer interposed therebetween are joined by cold drawing and heat treatment. A high-strength, high-corrosion-resistant composite wire, characterized in that there is substantially no intermetallic compound at the interface of these three members. 4. A steel core wire containing 3 to 50% by weight of Ni, a Ti or Ti alloy coating layer, and a Ni or Ni alloy layer interposed therebetween are cold drawn and less than 600 ° C. A high-strength and high-corrosion-resistant composite wire, which is joined by heat treatment of. 5. A steel core wire and a Ti or Ti alloy coating layer having a coverage of 20% or less in cross-sectional area are joined by cold drawing and heat treatment at a temperature of less than 600 ° C. A high-strength and high-corrosion-resistant composite wire characterized by the substantial absence of intermetallic compounds.