JPS6021350A - Hard material for watchcase with superior hot workability and mirror polishability - Google Patents

Abstract

PURPOSE:To obtain a hard material for a watchcase with superior corrosion resistance, scratch resistance, hot workability, mirror polishability and machinability by reducing the P and S content of a precipitation hardening Ni alloy to the utmost and adding specified amounts of Fe and/or Cu and Zr. CONSTITUTION:A watchcase is made of an Ni alloy consisting of <0.1% C, <3% Si+Mn, 25-37% Cr, <4% Fe+Cu, <0.20% Zr, 3-5% Al, <0.005% S+P, <0.02% N and the balance Ni. Since the P and S content is controlled, the Ni alloy has improved hot workability while maintaining superior corrosion resistance and hardness. Fe or Cu improves the machinability, and Zr converts Al2O3 inclusion causing a ''cyprinodont scratch'' into harmless ZrO2 inclusion to improve the mirror polishability.

Description

[Detailed Description of the Invention] This invention not only has the desired corrosion resistance but also has sufficient hardness to exhibit excellent scratch resistance, and also has extremely good hot workability and mirror polishability. This invention relates to hard watch case materials.

In general, watch case materials require high corrosion resistance, so brass and nickel silver have traditionally been used.

Alternatively, materials such as stainless steel have been widely used, but since all of these conventional materials are relatively soft, they tend to get scratched during use, making it extremely difficult to maintain their original beauty for a long time. .

For this reason, in recent years, various hard watch case materials have been proposed that have sufficient corrosion resistance and high hardness to resist scratches, and have been used to manufacture luxury products that can fully meet the demands of decorative items. Among these, for example, Japanese Patent Publication No. 55-21096 and Japanese Patent Publication No. 56-5815, which are relatively easy to process.
The current situation is that the demand for high-grade products is leaning towards precipitation hardening type Ni-based alloy materials as described in the above publication.
.

However, through hardening treatment, this precipitation-oriented Ni-based alloy has the hardness required for a hard watch case material: II
After v600, I came to fully satisfy the second requirement.

As long as it has sufficient functions to demonstrate its compensatory properties.
(i) It is difficult to mass-produce slabs using normal hot working methods due to their inherently poor hot workability. Because it has to be manufactured using the so-called small-scale method of cold processing (n+ machining), the monthly cost is high. However, the specular gloss deteriorates (general-purpose watch case made of SUS 30).
4), it had the problem of not being able to exude sufficient elegance to be used as a decorative item, and there was a strong demand for improvements from consumers.

From the above-mentioned viewpoints, the inventors of the present invention, in particular, aimed to provide a hard watch case material that not only has sufficient corrosion resistance and hardness, but also has excellent hot workability and specular gloss. Focusing on the precipitation hardening type N1-based alloy (Ni-cr-AQ gold alloy), which has relatively good corrosion resistance and high hardness among conventional hard alloys, we improved its hot workability and specular gloss. As a result of repeated research using ``N1-based alloys'', we obtained the following findings (a) to (''). Namely, (a) conventional precipitation hardening type N1-based alloys (
The factor that inhibits the hot workability of Ni-Cr-Ae gold alloys is the S and P elements mixed in as impurities from the molten raw materials, which exceed the austenite limit solid solution amount and form austenite in the cast structure. It precipitates in the form of low melting point compounds (sulfides, phosphides) at grain boundaries and acts to embrittle the grain boundaries.

Therefore, in order to improve hot workability, it is important to reduce S and P in the alloy to below the austenite limit solid solution amount. For example, by removing S and P in the melting process, When the content of O, OO is controlled to 5% or less, the hot workability of such a low S, low P ingot is dramatically improved compared to conventional alloys, making it difficult to perform normal forging and hot rolling. ′［
It is possible to fully manufacture plate materials by process, and mass production can be realized.

Figure 2 is a diagram showing the influence of the S and P contents in the alloy on hot workability, and the results are for an Okg ingot made in a vacuum induction furnace. Alloys other than the high S height 1 material corresponding to the alloy were subjected to preliminary treatment of de-S and de-P refining in the melting process. In addition, the N1 used
The basic Al1 composition of the base alloy is C: 0.01% (hereinafter, ``chi'' representing the component proportion is related to weight), Sj: 0.50%,
Mn: 1.50%, Cr: 36. OO%,
Ji'e: ], 50%, Cu: 1. o %, Z
r:0,01chi,All! : 3.80%, N: 0
．． 0], %, Ni and other impurities: remainder.

A test specimen heated to 1,000°C or 1,200°C was subjected to a drop weight test, and compressed at a rolling reduction rate of 30.
It was evaluated on a five-level scale shown in the table.

Table 1 and Figure 1 also show that hot workability is improved as the S and P contents in the alloy decrease;
It is clear that when p) is reduced to 0.005% or less, there is a significant improvement.

(b) However, if the amounts of S and P in the N1-based alloy are reduced, the machinability of the alloy deteriorates, making it difficult to perform efficient cutting.

(C) When one or both of Fe and Cu are added to the Machiki alloy with low S and P contents, the machinability of the alloy is improved and is equivalent to or even better than SUS 304 stainless steel. The material should exhibit good machinability as described above.

Figure 2 is a diagram showing the influence of li'e and P content in the alloy on machinability, and the basic composition is C: 0.01.
%, Si: 0.50%, Mg: 1.50%.

cr:z+5. oo%, Zr: 0.01%, A
Q: 3.80%.

S20,004%, P:0.001%, N:0
．． 01%.

This study investigated N1-based alloys containing
The number is a value obtained by comparing the tool life when cutting each sample, assuming that the tool life when cutting SUS 304 steel in a drilling test is 10'O.

From Fig. 2, the machinability is determined by Jre and Cu content in the alloy.
It can be seen that the improvement is improved as 1i increases.

(, 1) - On the other hand, the factor that impairs the specular gloss is the aforementioned "killer flaw", and the "killer flaw" is conventionally carried out at the final stage of refining in the melting process. This is caused by ΔQ203 inclusions generated by deoxidation, and the A+! 203 inclusions have poor adhesion to the base metal,
It must be formed by falling off during the mirror polishing process and exhibiting a pinhole shape.

(e) In order to prevent the occurrence of such "medaka flaws", Z
It is effective to add r and make a trace amount of Zr remain in the alloy.

That is, when Zr is added in this way, Zr exhibits an extremely good deoxidizing effect, reducing oxygen in the alloy even more than in conventional alloys, and also reduces Al! Even if ZrO is contained, residual oxygen can be effectively captured and ZrO
2 will be formed. And such ZrO'
Unlike Ae 203, Ae 2 does not cause "killer scratches", and therefore the alloy's excellent mirror polishing properties are ensured, and when polished, it produces a beautiful surface gloss comparable to that of SUS 304 steel. It becomes possible.

(f) In other words, in conventional precipitation hardening N1-based alloys, the S and P contents are kept sufficiently low, and F
By adding one or more of 6 and Cu and further adding Zr in a trace or residual amount in the alloy, the hot workability of the alloy is dramatically improved while maintaining good machinability. It is possible to mass-produce plate materials using the normal hot processing method.In addition, the mirror polishing properties are greatly improved and excellent mirror gloss can be achieved.I:U1FC, suitable for hard watch cases. High hardness A'4'-□1 is 1 (I et al.) 1.
Things.

This invention was made based on the above knowledge, (About one case of stool quality, C: O, l section and below.

,・31 and Mn: 3 or less in total amount.

Cr: 25-3'7%.

11.e and Cu: Total amount is 4 or less.

7. r: 0.20% or less.

Al4: 3-5%.

! (and P: 0005 or less in total tears) N: 0.02% or less.

N] and other unavoidable impurities, it not only has a hardness of Hv 600 or more, which is essential for hard watch cases, but also has good corrosion resistance and machinability.
It is characterized by having both excellent hot workability and mirror polishability.

The hard watch case of the present invention can be manufactured by performing the known pretreatment of de-S and de-P refining in the melting process, and then melting and refining in a vacuum induction furnace, etc.; It is preferable to add Zr as a deoxidizing agent before adding the Ae acid component at the final stage of refining in the melting process, and by doing so, Zr deoxidation, which is stronger than AQ, can proceed efficiently and oxygen in the alloy can be sufficiently reduced. At the same time, the remaining oxygen smoothly reacts with Zr and does not cause "killer flaws"#Z
This results in rO2-based inclusions.

Next, the reason why the composition ratio of chemical components constituting the hard watch case of the present invention is numerically limited as described above will be explained.

a) C If the C content in the alloy is high, C will precipitate as chromium carbide at the austenite grain boundaries during precipitation hardening treatment at a temperature of about 700°C, leading to deterioration of corrosion resistance. become. Therefore, it is preferable that the C content be as low as possible, and in particular, if it is 0.1% or less, the deterioration of corrosion resistance will not be noticeable, so the content is set at 0.1% or less.

L+) Si and Mn Although the Si and Mn components each have a deoxidizing effect on the alloy, Sl has a relatively strong deoxidizing ability, while Sl has a relatively weak deoxidizing ability. When combined with Jn, the deoxidizing effect becomes even stronger,
When this is used as a preliminary deoxidizing agent, deoxidation (2), which is carried out as a measure to prevent "medaka flaws", proceeds extremely effectively.However, if the amount of (Si-1-Mn) exceeds 3%, Since their inclusion would impair the hot workability of the alloy, the content of Si and 1 was set at 3% or less based on the maxim of both.

c) Cr The Cr acid component improves the corrosion resistance of the alloy and also increases the
' has the effect of accelerating the hardening rate by promoting the precipitation of ', but if the content is less than 25%, sufficient corrosion resistance cannot be obtained, while if the content exceeds 37%, the hot workability of the alloy is affected. The Cr content should be reduced to 25-3.
It was set at 7%.

d), , i''er and CuFe and CU components +/rC each have an equal effect of improving the machinability of Ni-based alloys, but even if each is added separately, the effect of improving machinability is small; Significant effects can only be brought about by adding both in combination.However, if the amount of (Fe+Cu) exceeds 4, it will impair the hot workability of the alloy.
The total content of both is set at 4% or less. In addition, the second
As is clear from the figure, the content of Fe and Cu (F
If the amount of (Fe-4-Cu) is less than 1%, the machinability improvement effect decreases rapidly, so the content is (Fe-4-Cu)
It is preferable that the amount is 1 or more.

e) Zr The Zr component is the most powerful deoxidizing agent for lactic acid-based alloys, converting Al!203-based inclusions that cause ``killer scratches'' into harmless ZrO2-based inclusions, resulting in a mirror-like finish. It has the effect of significantly improving abrasiveness.Also, since Zr is a strong deoxidizing agent, only a small amount (trace) remains in the alloy, and a sufficient effect can be obtained even when it is contained, but Zr is a strong deoxidizer. If the content is exceeded, hot workability will be impaired.
The Zr content was set at 0.20% or less.

f) The AA no-ε component has the effect of precipitating γ′ and hardening the alloy through precipitation hardening treatment at a temperature of about 700°C, but if its content is less than 3%, it will cause hardening of the hard watch case. Since it is not possible to achieve the required hardness of Hv600 or more, and on the other hand, if the content exceeds 5%, the annealing hardness will increase, making it difficult to form the case.
The ε content is set at 3 to 5%.

IW)S+ and PBoth 11 and P are elements that significantly deteriorate the hot workability of Ni-based gold, and it is preferable that they be as small as 1]7. In particular, the sum of the contents of both is U, (
] () If it exceeds 5%, hot workability deteriorates rapidly as shown in the diagram, making it difficult to mass-produce watch case materials using normal hot working methods. The content of P (S+P) was determined to be 0 and OO5% or less.

1+) Nl] is mixed as an unavoidable impurity in the alloy, but if its content exceeds 0.02%, ZrN
The N content was determined to be 002 or less because the N content was determined to be 002 or less.

Next, this invention will be concretely explained by comparing it with a comparative example using Examples.

Example First, alloy materials 1 to 10 having the compositions shown in Table 2 were melted in a vacuum induction furnace. At this time, materials 1 to 5 were subjected to preliminary treatment of de-S and de-P refining in the melting process, and further, Zr deoxidation was performed at the final stage of refining in the melting process, prior to addition of the Aε component. In addition, material 10 is SUS
It is a material equivalent to 304 stainless steel.

Next, these were made into ingots of 200 ky each,
A plate material with a thickness of 7 mm was manufactured using normal forging (heating temperature: 1200°C) and hot rolling (heating temperature: 1200°C) processes.

At this time, the presence or absence of cracks in the forging and hot rolling processes was examined to evaluate hot workability, and samples were taken from the obtained hot rolled sheets to determine the morphology of inclusions in the material, mirror polishability, Pressability, machinability, and hardness were measured.

The results are also shown in Table 2. 1°≠ The mirror polishability is 100. 40C)≠, and 10
After sequentially applying ρF polishing with 00'' emery paper, a separate cloth 0 polishing was performed, and the resulting mirror surface was evaluated by the presence or absence of killigrade flaws.

The pressability was evaluated by measuring the compression ratio under a constant load in a compression test using an Amsler tester and comparing the values.

In addition, the machinability 1r, as mentioned above, was evaluated by measuring the tool life by a drill test and comparing the values.From the results shown in Table 2, the present invention materials 1 to 5 +4
, Regarding pressability and hardness, conventional hard materials and times, etc. = +
71 performance, it has superior hot workability, mirror polishability, and machinability compared to conventional hard materials, and is suitable for general-purpose use.
It can be seen that it is almost equivalent to 5IJS 304 steel, which is 1 case month.

In particular, with regard to mirror polishability, which affects the aesthetic appearance of the product, the material of the present invention exhibited excellent performance without producing "killer flaws" and was able to achieve beautiful mirror gloss.

This improvement effect of Zr deoxidation reduces At! This is due to the effect of converting 203-based inclusions into ZrO2-based inclusions that do not cause defects, and at the same time improving the cleanliness of the 1-alloy material. As described above, the present invention provides a hard watch that fully satisfies the required corrosion resistance, hardness, pressability, and machinability, and also has extremely good hot workability and mirror polishability. It is possible to obtain a case material, and it is possible to mass-produce a hard watch case material with high decorative value at a low cost, thereby bringing about useful effects for industry-E.

[Brief explanation of drawings]

Figure 1 is a diagram showing the influence of the S and P contents in the Ni-base alloy on hot workability, and Figure 2 is a diagram showing the influence of the Fe and P contents in the Ni-base alloy on the machinability. It is a line diagram showing the influence. Applicant Nippon Stainless Co., Ltd. Agent Tomi 1) Kazuo and 1 other person

Claims (1)

[Claims] Weight is a percentage, C: 0 or less. S] and Mn: 3% or less in total amount. Cr: 25-37%. Fe and C+1: 4% or less in combined amount. Zr: 0.20% or less. Ae: 3-5%. S and 1]: 0.005% or less in combined amount. N: 0.02% or less. It is characterized by consisting of N1 and other unavoidable impurities and the remainder, and has excellent hot workability and mirror finish.