JPS6053735B2 - Exterior parts for mobile watches - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exterior part for a wristwatch that has excellent corrosion resistance, mechanical properties, and workability.

Traditionally, exterior parts for wristwatches have been made of brass or nickel silver, which is then plated with metal, or made of austenitic stainless steel, such as 18Cr-8Ni stainless steel, with a polished surface. It was served as a. However, in the case of exterior parts for wristwatches, because the shape is complex, when the plating is finished, the plating does not adhere well, but during carrying, sweat, seawater, etc. act on the gaps and cause corrosion, which reduces the value of the product. There have been cases of serious decline. The above-mentioned phenomenon was especially noticeable in exterior parts such as mesh bands. In recent years, Ni-based alloys have been used to solve these corrosion problems, but
In the case of current Ni-based alloys, although they can almost achieve their goals in terms of corrosion resistance, their workability is extremely poor, and parts that require a large number of processes, such as bands, are expensive. We were unable to provide the products that we needed.
The present invention obviates the drawbacks of the prior art as described above.

That is, based on Ni, which itself has excellent corrosion resistance, Cr, which has excellent corrosion resistance under oxidizing conditions, and Mo, which has excellent corrosion resistance under non-oxidizing conditions, containing chlorine ions, are added, and the mechanical properties are further improved by Nb. By doing so, we provide a highly corrosion-resistant material that can replace alloys that maintain corrosion resistance due to Cr, such as conventional austenitic stainless steels,
Moreover, the workability of the Ni-based alloy is improved to provide an inexpensive and high-quality exterior component. The alloy of the present invention, which is intended to improve the corrosion resistance and mechanical properties after plating of complex parts with poor plating coverage, such as exterior parts for portable watches, and to provide excellent workability, consists of the following chemical components.

In other words, in both weight ratios Cr (chromium) 16-25% Mo (molybdenum) 5-30% Nb (niobium) 0.5-1.5% Fe (iron) 5-25% C (carbon) 0.08% or less The remainder consists of Ni and unavoidable impurities.

Next, the reasons for limiting the addition range and composition range of each component will be described.

Ni is a useful base metal that has extremely excellent corrosion resistance, sufficiently dissolves Cr, Mo, and Nb in solid solution, and has significant characteristics in hardening alloys and improving corrosion resistance. Cr is an element that improves the strength of the alloy and significantly improves its corrosion resistance. In the case of Ni-based alloys with MO added as described below, 16% is required to maintain sufficient corrosion resistance even after activation treatment during plating. %is necessary.

However, when more than 25% is added, embrittlement of the alloy is observed.
If it exceeds 30%, processing into rods or plates becomes difficult, so the range of addition of Cr is limited to 16 to 25%. MO is an element that not only improves alloy strength but also exhibits excellent corrosion resistance in corrosive environments containing chlorine ions such as seawater, and its effect on corrosion resistance after plating becomes extremely noticeable from 5%. Become. The solid solubility limit of MO in Nl, which is the base of this alloy, is 30%, and if it exceeds this, workability will deteriorate and dissolution will become difficult, so it is limited to 5 to 30%. Nb is
It is an element that exhibits excellent hardenability in the N1-Cr matrix and greatly contributes to improving the mechanical properties of this alloy. It is also an element that stabilizes carbon and prevents corrosion resistance from decreasing due to precipitation of chromium carbide. However, since it is an active element, heat treatment is essential in the production of exterior parts.
For example, when using an ammonia decomposition gas furnace commonly used for annealing and brazing, undissociated ammonia and nitrogen in the decomposed gas tend to form a CrCbN nitride film on the surface of the material. This causes an obstruction to wettability and diffusivity. In the present invention, the addition range is limited to 0.5 to 1.5% in consideration of the effects and adverse effects of Nb addition described above. Since Fe is treated as a ferroalloy when dissolving Cr, approximately 5% of Fe is inevitably present.

In addition, as an exterior part for a wristwatch, it is essential that it can be manufactured at low cost, and the alloy of the present invention. Cr,
By adding MO in a well-balanced manner, corrosion resistance is not impaired even when Fe is added up to 20%, and the manufacturing cost of the material is also reduced. C strengthens the solid solution and improves its strength, but when used at around 800°C, Cr
Efforts should be made to reduce this as much as possible, as it forms carbides and deteriorates corrosion resistance.

However, 0. If it is within the range below the bean paste, it will be fixed by the above-mentioned effect of adding Nb, so it is limited to 0.08% or less.
Precious metal plating for decorative effects includes gold, silver,
The noble metals palladium, rhodium, ruthenium, iridium, platinum and their alloys are all viable.

The plating thickness is 2~2 for Au-CO alloy plating.
10μ, 0.1 to 4μ for Au-Ni-1n, P9-
The optimum value is 1 to 10μ for Ni, and 0.2 to 0.5μ for Rh. Next, the usefulness of the present invention will be explained based on Examples.

[Example 1] Crl 6%, MO 5%, Nb in weight ratio
O. 5%, Fe5%, CO. A mesh band for a wristwatch was made from an alloy consisting of 3% O, the balance M, and unavoidable impurities using a 0.67 mφ wire rod as a raw material.

This bandono and 17Cr-15Ni 10.02%
A band made of C austenitic stainless steel was manufactured. After solution treatment, nickel sulfate 100
y/e, 5A/d resistance in an aqueous solution of 50ml/e of concentrated hydrochloric acid,
3. Activate by electrolytic treatment as described in Section 2, 24K gold strut, 4μ Au-CO alloy plating, Au-
A 2μ Ni-In alloy plating was applied. Next, we conducted a corrosion resistance test by immersing it in artificial sweat and immersing it in 5% saline solution for 7 days. In the case of bands made of stainless steel, the gold plating on the band surface peeled off and significant red rust appeared on the entire surface. . However, in the band obtained according to the present invention, no peeling was observed, and no rust was observed at all. The mechanical properties of the product of the present invention include Vickers hardness of 200, tensile strength of 65k9/Wn2, and elongation of 42% after solution treatment.
It was hot. [Example 2] Weight ratio: 25% Cr, MO
3O%, Fe25%, Nbl. 5%, CO. O8%.

Example-1 Alloy consisting of balance N1 and unavoidable impurities
After producing a mesh band for a wristwatch in the same manner as above, this band and Crl5% produced in the same manner as above,
A band made of Inconel 600 consisting of 7% Fe and the balance Nj was activated and plated in the same manner as in Example 1, and then subjected to a corrosion resistance test. As a result, the Ni-based alloy showed red rust and green color. Compared to the rust that appeared in dots,
No abnormality was observed in the alloy of the present invention. In addition, regarding the mechanical properties of the product of the present invention, the tensile strength is 68k9.
/Second 2, it showed excellent properties with an elongation of 40%.Also, especially for products that require many processing steps such as mesh bands, the workability of the material has a large impact on the cost, but the alloy of the present invention and Ni
Compared to the base Inconel material, the alloy of the present invention has an applied force ratio of 7.
It can be processed with 0% man-hours and has a large cost reduction effect. As described above, the effect of the present invention is achieved by adding Cr, MO, and Nb to the Ni base in a well-balanced manner.
The purpose is to eliminate the poor workability characteristic of one type of steel, maintain mechanical properties and excellent corrosion resistance, and reduce costs by adding up to 25% Fe.

Furthermore, the present invention is applicable to mobile watch cases, glass rims, watches,
Needless to say, it can be used for general exterior parts such as bezels, spring bars, and buttons.

Claims (1)

[Claims] 1 All weight ratio: Cr16~25%, Mo5~
30%, Nb0.5-1.5%, Fe5-25%, C0
．． 1. An exterior part for a portable watch, characterized in that the material is made of an alloy consisting of 0.8% or less Ni and unavoidable impurities, and is plated with a precious metal or an alloy thereof after activation treatment.