JPH0122354B2 - - 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, the plating does not adhere well when finished due to their complex shapes, and sweat, seawater, etc. act on the gaps during carrying, causing corrosion and reducing the value of the product. There have been cases where it has significantly decreased.

Mesh bands in particular are popular because they fit well on the wrist when used as wristwatches, and the surface can be processed 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. Therefore, required properties suitable for processing such as tensile strength and elongation must be met at the same time.

For this purpose, a method of plating using austenitic stainless steel with excellent corrosion resistance, such as 18Cr-8Ni stainless steel, is being considered, but these stainless steels require activation treatment to improve the adhesion of plating. Since the passive film of Cr is removed, it becomes chemically unstable. Therefore, if there are areas where the plating cannot reach, the material easily rusts, making it unsuitable for practical use.

On the other hand, materials such as Hastelloy (trade name) or Inconel (trade name), which are Ni-based alloys, have been used in some cases in recent years to compensate for the shortcomings of these conventional materials, but these materials are insufficient in terms of improving corrosion resistance. Although the object could be achieved, the elongation when made into a wire was insufficient, and in terms of workability and material cost, it was insufficient for widespread use as mesh bands for portable watches.

In addition, materials with good corrosion resistance and plating properties that are suitable for mesh processing have not been found.
Although there is a similar description in No. 120220, there is no clear description of mechanical strength or elongation, and it is unclear whether it is suitable for spiral processing such as mesh bands.

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 was done 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, it becomes a highly corrosion-resistant material that replaces alloys that maintain corrosion resistance with Cr, such as conventional austenitic stainless steels, and by adding Fe for use as ferroalloys, it reduces costs and increases elongation. The workability of the spiral was improved by improving the processability of the spiral by increasing the
V, Ti, Nb, and Ta are used to maintain material processability and corrosion resistance after brazing for use in portable watches.

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

That is, in weight ratio, Cr (chromium) 16-25% Mo (molybdenum) 5-25% Cu (copper) 1-3% Fe (iron) 5-8% V (vanadium) 0.2-0.3% C Contains (carbon) 0.03% or less Si (silicon) 0.3% or less Mn (manganese) 1% or less, and a composite of at least two types of Ti (titanium), Nb (niobium), and Ta (tantalum) in a total amount It contains 0.5 to 0.8%, with the remainder consisting of Ni and unavoidable impurities, and is plated with precious metals.

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 not only improves alloy strength but also exhibits excellent corrosion resistance against corrosive environments containing chlorine ions such as seawater. is limited to 5% to 25%.

Like Mo, Cu is an element that exhibits excellent corrosion resistance in corrosive environments containing chlorine ions and also contributes to plating properties. It is preferable that the amount does not exceed 3% as it does not necessarily give good results in terms of corrosion resistance, and less than 1% is not sufficient in consideration of plating properties and corrosion resistance.

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. In addition, for mesh bands for mobile watches, it is essential that they can be manufactured at low cost, and by adding Cr and Mo in a well-balanced manner, this alloy does not impair corrosion resistance even when Fe is added up to 8%. , and the cost of materials can also be reduced.

C strengthens the solid solution and improves the strength, but
When used at temperatures around 800°C (for example, when brazing the case and band), Cr and carbide form, deteriorating corrosion resistance and strength, so efforts should be made to reduce this as much as possible. However, if it is within the range of 0.03% or less, it will be fixed by adding Ti, Nb, Ta, etc., so it is limited to 0.03% or less.

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

V is recognized to be effective in strengthening the alloy and refining the crystals, but if it is less than 0.2%, the grains will not be refined sufficiently, and if it is added in excess of 0.3%, it will become brittle.

Other trace addition elements Ti, Nb, and Ta have the effect of preventing the precipitation of Cr carbides as mentioned above.
By using them in combination, not only the precipitation of Cr carbides is prevented, but also the mechanical strength is improved, and the range of 0.5 to 0.8% 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, and this significantly reduces the wettability of the solder.

Mn is inevitably present in an amount of about 1% in order to melt the material at low cost, and if it is less than 1%, it will not have any effect on the properties targeted for this alloy.

Next, examples of the present invention will be shown.

Example 1 Weight ratio: Cr16%, Mo5%, Cu1%, Fe5%,
C0.03%, V0.2%, Si0.3%, Mn0.6%, Ti0.2%,
A wristwatch mesh band was manufactured from an alloy consisting of 0.3% Nb, the remainder Ni, and unavoidable impurities, using a 0.6 mmφ wire rod as the raw material. After solution treatment,
This was activated by cathodic electrolysis treatment for 30 seconds at 5 A/dm ² in an aqueous solution of 100 g of nickel sulfate and 50 ml of concentrated sulfuric acid. After gold strike plating, Au-Co
Alloy (12K to 14K) plating 4μ, Au-In alloy (18K
~22K) 2μ plating was applied. This band and 17Cr with similar activation treatment and plating treatment
−15Ni, 0.02% low carbon austenitic stainless steel band soaked in artificial sweat, 5
When a corrosion resistance test was conducted by immersing the band in a saline solution for 7 days, in the case of a band made of stainless steel, the gold plating on the surface layer peeled off and significant red rust appeared on the entire band surface. However, in the band obtained according to the present invention, there was no peeling of the plating and almost no rust was observed. In terms of mechanical properties, the tensile strength is 58Kg/
It showed excellent properties with mm ² and elongation of 40%.

Example 2 Weight ratio: Cr25%, Mo25%, Cu3%, Fe8
%, C0.03%, V0.3%, Si0.3%, Mn0.5%, Ti0.1
%, Nb 0.5%, Ta 0.2%, balance Ni and unavoidable impurities. After preparing a mesh band for a wrist watch in the same manner as in Example 1, it was activated and plated in the same manner. A corrosion resistance comparison test was carried out in the same manner as in Example 1 using this band and a band made of 20Cr-30Ni austenitic stainless steel manufactured in a similar manner. In the case of , red rust occurred on the entire surface, but
No abnormality was observed in the band obtained according to the present invention. In terms of mechanical properties, tensile strength is 65Kg/
mm ² and elongation was 34%.

In addition, to give a good example of the plating made of noble metal or its alloy in the present invention, Au-Co (12~
14K) 0.5 to 5μ, Au-In (18 to 22K) 0.5
~5μ, Pd−Ni (weight ratio of Pd to Ni: 40~80:60~
20, preferably 60:40), 0.5 to 5μ, Rh, 0.5
~1μ, and the plating as described above is applied in a single layer or in layers.

As described above, according to the present invention, material elongation is improved by adding Cr, Mo, and Cu in a well-balanced manner to a Ni base, and adding 5 to 8% Fe while maintaining corrosion resistance. By adding Ti, Nb, and Ta in combination, it not only prevents the precipitation of Cr carbides but also improves mechanical strength and improves C, Si. , Mn, etc. in a predetermined amount, if the elongation is too large, the material for the mesh band will tend to elongate or become stiff during spiral processing, and if the elongation is small, it will be difficult to cut or form a spiral. , we were able to secure an appropriate elongation of 34-40%, and a tensile strength of around 60 kg/mm ² , making it a well-balanced material for wire rods for mesh bands, with good processability, and for example, when used on a mesh knitting machine. Even with spiral processing, mesh knitting can be easily performed without cutting or twisting into helices.

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, like mesh bands for mobile watches,
Even if the plating has poor adhesion, there will not be much potential difference between the material and the precious metal plating film, and the material itself has good corrosion resistance, so it has sufficient corrosion resistance against sweat and seawater, and is inexpensive. We can provide excellent mesh bands for mobile watches.

Claims (1)

[Claims] 1. All in weight ratio: Cr16~25%, Mo5~25%, Cu1~3%, V0.2~
0.3%, Fe5~8%, C0.03% or less, Si0.3% or less,
The material must be made of an alloy containing Mn of 1% or less and at least two of Ti, Nb, and Ta at 0.5 to 0.8%, with the remainder being Ni and unavoidable impurities, and metal plating made of a precious metal or its alloy. A mesh band for mobile watches featuring the following.