JPS5927378B2 - Watch manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a watch made of a Ni-Cr-At alloy.

Generally, the watch side of a wristwatch is used in close contact with the human body and exposed to the outside air for long periods of time, so it is easily corroded by sweat and rainwater.

Moreover, the surface is easily scratched by impact, so these watches must have corrosion resistance and high hardness.

And when processing the shape as a watch side, its acid formation,
Materials with excellent properties such as ease of polishing are required.

However, as a material for the second watch side. Stainless steel (SU
S-304) etc. are often used.

Although this material has excellent corrosion resistance, it has a Vickers hardness of Hv 250, and there are problems such as scratches on the surface and loss of gloss and beauty after use for about 6 months to 1 year. Ta.

For this reason, various materials have been developed in recent years.For example, a method has been developed to obtain a highly hard watch side by sintering a Cr-Mo-W-Fe alloy with poor machinability using a powder metallurgy method. has been done.

However, products made using powder metallurgy have poor dimensional accuracy and are not suitable for watches that require precision; they are brittle against impact and have many fine pores, so surface polishing and other surface treatments are required. There were drawbacks such as difficulty.

The present invention was developed as a result of various studies in view of these drawbacks.
By applying cold plastic working to the Ni-Cr-A1 alloy after solution treatment, it can be processed easily and precisely.
It is an object of the present invention to provide a manufacturing method for a watch that can obtain a watch with extremely high hardness by subjecting it to an aging treatment after processing.

Hereinafter, the present invention will be explained in detail. 2. When the Ni-Cr-At alloy forming the watch side according to the present invention is subjected to aging treatment, α phase, γ phase, γ' phase, etc. are combined and precipitated, resulting in high hardness. will occur.

Therefore, in the alloy according to the present invention, Ni is an element that not only improves toughness but also has excellent corrosion resistance.

In addition, Cr has excellent corrosion resistance like Ni, and
It acts to promote precipitation of α phase by grain boundary reaction.

The concentration range in which the α phase precipitates in a layered form due to the inclusion of Cr is 30 to 55 (hereinafter, ``chi'' indicates the weight), but 4
If the concentration exceeds 5%, the ductility in cold conditions will drop significantly and cold working will not be possible, so the concentration range is 30~
45% is preferred.

At is an element that promotes composite precipitation in the alloy according to the present invention, and when contained in a small amount, it has the effect of significantly improving age hardenability.

This action is as shown in the graph of the drawing, 40%Cr-4%
When an At-Ni alloy is solution-treated at 1200°C for 1 hour and then aged at 700°C for 0.5 hours, the hardness after aging is approximately Hv 670, compared to 40% that does not contain At. The hardness of Cr-Ni alloys hardly increases with aging treatment.

The reason for limiting the At content to 2.5 to 5% is 2.
．． If the content is less than 5%, sufficient composite precipitation will not occur even after aging treatment, and the necessary hardness cannot be obtained.If the content exceeds 5%, the hardness after solution treatment will be Vickers and H.
This is because v is 300 or more, and cold workability and cutting workability are significantly reduced.

In addition to the above alloy components, if necessary, A such as Ti may be added.
Similar to t, by having a GCP phase-forming acid-forming element, age hardening due to the same complex precipitation can be obtained.

Further, by containing 2% or less of Si, the wear resistance can be further increased.

Further, in the alloy of the present invention, for example, a trace amount of Mn may be added as a deoxidizing agent.

Furthermore, a part of Ni may be replaced with Co.

The alloy according to the present invention having the above alloy composition requires solution treatment and cold working as a step before aging treatment, and the conditions will be explained below.

The alloy according to the present invention having the above composition has a 1000 to 1200
Solution treatment is performed at ℃ to dissolve the alloying elements.

The solution treatment time is not particularly limited, but from the viewpoint of work efficiency, the higher the treatment temperature, the shorter the treatment time, and in particular, it is recommended to perform it at 1100 to 1200°C for several minutes to several minutes. is desirable.

With this solution treatment, the hardness Hv is reduced to about 200 to 300, and cold plastic working is performed at around room temperature.

The present invention is characterized by including a cold working step as the next step after the solution treatment.

This process is not only advantageous in manufacturing as a forming process such as precision forging, but the processing strain accumulated inside this process has an effect in the next aging treatment, improving the hardness reached at 2-age aging and significantly lowering the aging temperature. be able to.

Next, the alloy solution-treated as described above is further added to 400 to 95
By aging at 0°C, preferably at 450 to 600°C, a layered composite precipitated layer consisting of α phase, γ phase, and γ' phase is formed to improve hardness.

Moreover, the aging treatment time is sufficient for about 30 minutes, and if the aging treatment is too long, there is a risk that the hardness will decrease.

The aging treatment temperature shifts significantly to the lower temperature side due to the introduction of working strain, but when the aging temperature is less than 300°C, the precipitation of the γ' phase is insufficient, especially in those with a low At content, and the effect of composite precipitation is small, and If it exceeds .degree. C., the amount of layered precipitation becomes granular and the hardness decreases, which is not preferable.

Next, examples of the present invention will be described.

First, 38%Cr -3,8%At -0,5%M
The alloy according to the present invention consisting of n - balance Ni was melted and cast into a shape similar to a watch side, then solution treated at 1200°C for 0.5 hours and cold forged at various processing rates.

Figure 1 shows the average processing rate and hardness after processing, and strain hardening was observed even at a fairly low processing rate.

When aging treatment was performed for 2 hours at various aging temperatures with 55 inches of processing strain still present, the maximum hardness was approximately H
Improved with v780.

Achieves hardness that does not require sanding.

Furthermore, the aging temperature was significantly lowered, reducing heat treatment costs and oxidation loss.

In particular, the gloss polishing process under high hardness conditions was significantly shortened.

This is then given a mirror finish to form the watch side.

In order to investigate the corrosion resistance of the watch side created in this way (
1) 20% NaCl aqueous solution? (2) 5% NH30H aqueous solution? (3) 5-H2SO4 aqueous solution, and (4) 5-Hybrid lactic acid aqueous solution.

As a result, even after being immersed for 72 hours, the metallic luster remained intact and the product remained beautiful.

It was confirmed that it has corrosion resistance comparable to stainless steel (SUS304).

Similarly, the material with an average processing rate of 82 was heated to 650°C.

When each was aged separately at 700°C, hardnesses Hv of 687 and 646 were obtained, respectively.

As is clear from the above results, the watch of the present invention has excellent corrosion resistance comparable to that of conventional stainless steel, and has significantly improved resistance to scratches due to maximum hardness. Moreover, it has become possible to reduce process costs by lowering the temperature of cold forming and aging treatment.

It should be noted that it is within the scope of the present invention to insert a machining process between cold working and aging treatment in the two processes, and furthermore, cold forged stock material can be processed by hot working methods etc. instead of precision casting. It is also easy to think of doing it differently.

[Brief explanation of drawings]

Figure 1 shows the relationship between the average working rate of cold forging of the invention alloy and the hardness after working, and Figure 2 shows the relationship between the average working rate and the hardness after processing of the invention alloy. FIG. 3 is a diagram illustrating the relationship between hardness and aging temperature in comparison with the case where no cold working is performed.

Claims (1)

[Claims] 1 Cr 30-45% by weight, /u 2.5-5% by weight. A method for manufacturing a watch, which comprises performing cold plastic working on an alloy formed by solution treatment, the remainder of which is Ni, and then subjecting it to aging treatment.