JPH0125820B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mesh band for a portable watch using a material having corrosion resistance and workability suitable for the mesh band.

Traditionally, exterior parts for wristwatches have been mainly made of brass or nickel silver, plated with nickel, and then plated with gold, palladium, rhodium, or an alloy thereof. Alternatively, they were made of austenitic stainless steel, such as 18Cr-8Ni stainless steel, and were used as exterior parts for wristwatches with a polished surface. However, in the case of exterior parts for wristwatches, since they have a complicated shape, there have been cases where sweat, seawater, etc. interact with the gaps during carrying, causing corrosion and significantly reducing the value of the product.

Mesh bands are especially popular because they fit well on the wrist when used as wristwatches, and the surface can be patterned with various patterns.
Since this is spiral-processed and knitted into a product, it is required that corrosion does not occur even if sweat remains in the stitches, and as mentioned above, wire processing and spiral processing are required. Therefore, required properties such as tensile strength and elongation suitable for processing are required at the same time.

On the other hand, materials such as Hastelloy or Inconel, which are Ni-based alloys, have been used in some areas in recent years to compensate for the shortcomings of these conventional materials. Although these materials can sufficiently achieve the purpose of improving corrosion resistance, The elongation of the material was insufficient when it was made into a material, and it was insufficient in terms of processability and material cost to be widely used as a mesh band for portable watches.

Also, although there is a similar description in JP-A-52-120220, there is no clear description of mechanical strength or elongation, and it is not clear whether it is good for items that undergo spiral processing such as mesh bands. It is unknown.

The present invention eliminates the above-mentioned drawbacks, makes use of the excellent corrosion resistance of Ni-based alloys, and optimizes the elongation of Ni-based alloys into wire rods, reducing spiral workability and reducing material costs. This invention was developed in order to provide a mesh band for a portable watch that has excellent corrosion resistance. In other words, based on Ni, which itself has excellent corrosion resistance, Cr, which has excellent corrosion resistance under oxidizing conditions, and Cr, which has excellent corrosion resistance under non-oxidizing conditions containing chlorine ions,
By adding Mo and Cu, and further adding Fe for use as ferroalloy, we can reduce costs, improve elongation and improve spiral workability, and add trace elements such as C,
Si, V, Ti, Nb, and Ta are used to maintain material processability and corrosion resistance after brazing, which is essential when used as a mesh band for a portable watch. In addition to the excellent corrosion resistance and workability as described above, the present invention is also characterized by the addition of W to increase mechanical strength.

The alloy of the present invention, which is intended to improve the corrosion resistance, mesh workability, and strength of parts with complicated shapes such as mesh bands for mobile watches, has the following chemical components.

That is, in terms of weight ratio, Cr (chromium) 16-25% Mo (molybdenum) 5-9% Cu (copper) 1.5-3.5% Fe (iron) 5-8% W (tungsten) 2-3% C (Carbon) 0.03% or less V (vanadium) 0.2 to 0.3% Si (silicon) 0.3% or less Mn (manganese) Contains 1% or less, and is a composite of Ti (titanium), Nb (niobium), and Ta (tantalum). Contains 0.6-1%,
The remainder consists of Ni and unavoidable impurities.

Next, the effect of adding each component and the reason for limiting the composition range will be described.

Ni has very good corrosion resistance, and Cr, Mo,
It is a useful base metal that sufficiently dissolves Cu and has a great effect on strengthening alloys and improving corrosion resistance.

Cr is an element that improves the strength of the alloy and significantly improves its corrosion resistance.
In case of addition, 16% is required to maintain sufficient corrosion resistance. However, if it exceeds 25%, the alloy becomes brittle, and if it exceeds 30%, it becomes difficult to process it into mesh wire, so the addition range of Cr is set at 16 to 25%.

Mo is an element that improves alloy strength and exhibits excellent corrosion resistance against corrosive environments containing chlorine ions such as seawater. Considering the effect of increasing strength through addition, and considering that the element itself is expensive, 5.
Limited to ~9%.

Cu, like Mo, is an element that exhibits excellent corrosion resistance in corrosive environments containing chloride ions, but as with Monel, where increasing the amount of Cu added lowers corrosion resistance, increasing the amount added does not necessarily improve corrosion resistance. It is preferable that the content does not exceed 3.5% without any negative effects, and if corrosion resistance is taken into consideration, less than 1.5% is not sufficient.

Fe is treated as ferrochrome rather than metal Cr when melting Cr, and 5 to 8% of Fe is added to improve elongation. If it is less than 5%, elongation will not be sufficient, and if it exceeds 8%, corrosion resistance will decrease.

Furthermore, by adding Cr and Mo in a well-balanced manner, corrosion resistance is not impaired even when Fe is added up to 8%, and the cost of the material can also be reduced.

Like Mo, W is an element that exhibits excellent corrosion resistance against a corrosive environment containing chlorine ions, and also has an extremely high elastic modulus of itself and significantly strengthens the strength of the solid solution of the alloy. Such an effect is caused by Mo
If it is less than 2%, the effect will be small, and if it exceeds 3%, the workability will be reduced.

C strengthens the solid solution and improves the strength, but 800
When used around ℃ (for example, brazing in the case of exterior parts such as mesh bands for mobile watches)
Since Cr forms carbides with Cr and deteriorates corrosion resistance and strength, efforts should be made to reduce it as much as possible. However, if it is within the range of 0.03% or less, Ti,
0.03% because it is fixed by adding Nb, Ta, etc.
It is limited to the following.

Similar to Ti, Nb, and Ta mentioned above, Si is limited to 0.3% or less in order to suppress the precipitation of Cr carbides when used at around 800°C and to maintain the corrosion resistance after brazing in the above-mentioned exterior parts.

V has been shown to have the effect of strengthening the alloy and refining the crystals, but if it is added in an amount exceeding 0.3%, it will become brittle, and if it is less than 0.2%, the refining of the crystals will not be sufficient.

Other trace addition elements Ti, Nb, and Ta have the effect of preventing the precipitation of Cr carbides as mentioned above.
When used in combination, it not only has the effect of preventing precipitation of Cr carbides, but also improves mechanical strength, so a range of 0.6 to 1% is preferable. The composition was limited to this range because nitrides are easily formed in an ammonia decomposition gas furnace used when brazing mesh bands for mobile watches, which significantly reduces the wettability of the solder.

Mn is inevitably present at about 1% in order to melt the material at low cost. Moreover, if it is 1% or less, it will not have any influence on the properties aimed at by this alloy.

Next, examples of the present invention will be shown.

<Example 1> Weight ratio: Cr16%, Mo5%, Cu1.5%, Fe5
%, W2%, C0.03%, V0.2%, Si0.3%, Mn0.6
%, Ti 0.2%, Nb 0.3%, Ta 0.1%, the remainder Ni and unavoidable impurities.A wire rod with a diameter of 0.6 mm was produced, and a mesh band for a wristwatch was made from this wire. When this band and a band made of low carbon austenitic stainless steel with 17Cr-15Ni and 0.02% C were immersed in artificial sweat and 5% saline for 7 days, corrosion resistance tests were conducted. In some cases, significant red rust occurred on the entire surface of the band. However, in the band obtained according to the present invention, almost no rust was observed. In terms of mechanical properties, it showed excellent tensile strength of 63 kg/mm ² and elongation of 45%.

<Example 2> Weight ratio: Cr25%, Mo9%, Cu3.5%, Fe8
%, W3%, C0.03%, V0.3%, Si0.3%, Mn0.5
%, Nb 0.5%, Ta 0.2%, the balance Ni and unavoidable impurities.
Similarly, a mesh band made of 20Cr-30Ni austenitic stainless steel was used as an example.
A corrosion resistance comparison test was conducted in the same manner as in 1. As a result, in the case of a band made of austenitic stainless steel as described above, red rust occurred on the entire surface, but no abnormality was observed in the band obtained by the present invention. In terms of mechanical properties, tensile strength is 65Kg/ ^mm2 ,
The elongation value was 35%. The hardness of the material of the present invention after solution treatment is about 200 to 250 Hv, which is comparable to that of ordinary stainless steel and has excellent workability.

As described above, according to the present invention, the elongation of the material is improved by adding 5 to 8% Fe to the Ni base while maintaining corrosion resistance by adding Cr, Mo, and Cu in a well-balanced manner. By adding Ti, Nb and Ta in combination, the precipitation of Cr carbides is prevented and the mechanical strength is improved, and by adding W. By reinforcing the strength of the solid solution and adding a certain amount of C, Si, Mn, etc.,
For mesh band materials, if the elongation is too large, it will tend to elongate or become stiff during spiral processing, and if the elongation is too small, it will be difficult to cut or form spirals, but an appropriate elongation is 35 to 45%. Mechanical strength is 60~
Since we were able to secure a range of 65Kg/mm ² , it became a well-balanced material for wire material for mesh bands.
It has good workability, and even when spirally processed using a mesh knitting machine, it does not break or become helical, making mesh knitting easy.

In addition, even in mesh bands for mobile watches, formation of a passivation film is extremely rare.
The brazing performance with the case body can also be improved.

Furthermore, since the material itself has good corrosion resistance, it exhibits sufficient corrosion resistance against sweat and seawater, making it possible to provide an inexpensive and excellent mesh band for a portable watch.

Claims (1)

[Claims] 1. All in weight ratio: Cr16~25%, Mo5~9%, Cul.5~3.5%, V0.2
~0.3%, Fe5~8%, W2~3%, C0.03% or less,
The material is an alloy containing 0.3% or less of Si, 1% or less of Mn, and 0.6 to 1% of at least two of Ti, Nb, and Ta, with the remainder being Ni and unavoidable impurities. A mesh band for mobile watches.