JPH08199265A - Ornamental titanium alloy and its production - Google Patents

Abstract

PURPOSE: To obtain an ornamental titanium alloy having satisfactory workability and improving specular property, scuffing and wear resistances. CONSTITUTION: Titanium is mixed with 1-3wt.% iron powder and 9-10wt.% niobium powder and the resultant mixture is sintered at 1,300-1,400 deg.C to attain high density. In this state, forming or working is carried out, high hardness is ensured by rapid cooling to 900-950 deg.C and specular property, scuffing and wear resistances are improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a decorative titanium alloy produced by powder metallurgy.

[0002]

2. Description of the Related Art Decorative items such as wristwatches made of pure titanium for commercial use have small scratches on the surface even after polishing because the pure titanium is soft, and the mirror surface is difficult to appear. In addition, shot blasting is performed in order to make the surface state even when it is hardened by nitriding treatment, so that a rough gray surface state is obtained. On the other hand, titanium alloy is difficult to cold forge because of its high strength, and hot forging or isothermal forging is generally used for forming decorative parts such as wristwatch exterior parts, but it is difficult to obtain dimensional accuracy.

[0003]

However, when stainless steel is used as a material for decorative parts, particularly wristwatch exterior parts, as in the prior art, it has low hardness and is easily scratched, has a large specific gravity, and has a skin allergy due to Ni. There is a problem that it may occur, or it may not rust completely against seawater and may rust. Also, when commercial pure titanium is used as a decorative component material, it is superior to stainless steel in terms of lightness, corrosion resistance, and skin allergy, but the surface roughness deteriorates due to hardening treatment, and the surface condition It is limited to a rough gray color. Therefore, there is a problem that the design becomes unitary and the high-class feeling is significantly impaired.

On the other hand, when a titanium alloy is used as a decorative component material, a mirror surface can be easily obtained and a high-grade feeling can be obtained. Although forging is used, there is a problem that it is difficult to obtain dimensional accuracy. Therefore, an object of the present invention is to solve such problems in the related art, while maintaining good workability, high hardness, light weight, good biocompatibility, good corrosion resistance, and specularity and scratch resistance. To obtain a titanium alloy of high quality.

[0005]

In order to solve the above-mentioned problems in the conventional powder metallurgy of titanium and titanium alloy, the present invention contains titanium powder in an amount of about 2% by weight, that is, 1%.
After mixing ~ 3% iron powder and 9.5% near, i.e. ~ 10% niobium powder, sintering is performed at 1300 to 1400 ° C and molding is performed in the state of good workability, and then 900- After heating at 950 ° C., quenching was performed by quenching.

[0006]

By performing the above treatment, it is possible to increase the density and improve the workability, so that a titanium alloy having high specularity and scratch resistance can be obtained.

[0007]

Embodiments of the present invention will be described below.

[0008]

[Table 1]

(Example 1) The average size of powder particles is 4
Pure titanium powder of 5 μm, iron powder of 45 μm on average and niobium powder of 5 μm on average were mixed at the ratio shown in Table 1 to obtain 7 kinds of mixed powder. Φ at a pressure of 50 kgf / mm ²
Molded into a cylindrical shape having a thickness of 10 mm and a thickness of 15 mm to obtain a molded body. Next, these molded bodies were subjected to 1250 ° C, 1350 ° C,
It was kept at 1450 ° C. for 30 minutes to obtain a sintered body.

FIG. 1 shows the relative density of each sintered body. The relative density of each sintered body is less than 95% in all sintered bodies when sintered at 1250 ° C., and there is variation in the structure, so that it cannot be used as a decorative article. 1350
When sintered at ℃, 1450 ℃, all the sintered body is 95
% Or more, the structure becomes a uniform α + β two-phase structure,
It was sufficiently durable to be used as an ornament.
Next, a rolling test was conducted to examine the workability of the sintered body that was sintered at 1350 ° C and 1450 ° C. The results are shown in Table 2.

[0011]

[Table 2]

As can be seen from Table 2, the yield strength of the sintered body sintered at 1350 ° C. is lower than that of the sintered body sintered at 1450 ° C. Further, the occurrence of edge cracks in each sintered body at the same rolling rate of 30% was smaller in the one sintered at 1350 ° C. Also, when observing the tissue,
The sintered body sintered at 50 ° C. has a large average particle size.
Therefore, it can be said that the sintered body sintered at 1350 ° C has better workability. On the other hand, when the amount of iron powder increases, the relative density of the sintered body increases, but the workability becomes poor. Further, reducing the amount of iron powder and increasing the amount of niobium resulted in difficulty in increasing the density. From these results, it is possible to densify and improve workability by sintering a mixed powder of 1 to 3% iron powder and 9 to 10% niobium powder at a sintering temperature of 1300 ° C to 1400 ° C. Became.

(Example 2) Of the seven sintered bodies obtained by the method described in Example 1, those sintered at 1350 ° C. were 750, 800, 850, 900, 950, 100.
Each was heated at 0 ° C. for 30 minutes, and from that temperature was rapidly cooled by water cooling (quenching treatment).

FIG. 2 shows the hardness of the sintered body before and after the quenching treatment. The hardness of 100Ti (component A) remains the same as the sintered body even if the quenching temperature is raised, but the sintered bodies B, C, D and E containing iron powder are hardened by raising the quenching temperature. Is gradually increasing. The increased hardness makes it less likely to be scratched, and is extremely effective when used as a decorative item. Further, the sintered bodies C and D containing the iron powder and the niobium powder showed a larger inclination of increasing hardness after quenching than the sintered body B containing no niobium. However, similarly, in the sintered body E containing the iron powder and the niobium powder, the slope of increase in hardness was smaller than that of the sintered body B containing no niobium. Further, the hardness of the sintered bodies F and G containing no niobium powder but no iron powder gradually increases with increasing quenching temperature, but does not increase so much.
Next, each sintered body was subjected to quenching treatment, and then mirror-finished by buffing. Table 3 shows the evaluation results of the mirror surface state of each sintered body after the quenching treatment.

[0015]

[Table 3]

Since 100Ti has an α single phase structure and low hardness after sintering, waviness occurs in the surface state after polishing, and a mirror surface cannot be obtained. Further, even if the quenching treatment is applied, the structure and hardness do not change significantly, and the specularity does not change.
The hardness of the F and G sintered bodies containing only niobium powder gradually increased by the quenching treatment, but the hardness did not so much and the mirror surface property was not obtained. Further, in the B powder containing only the iron powder, a coarse α phase of about 100 μm is precipitated in the β ground after sintering, so that the β phase and the α phase have a difference in the polishing property and the specularity is slightly deteriorated. ing. However, when the quenching treatment temperature was 900 ° C. or higher, needle-like martensite and residual β structure were formed, and unevenness due to polishing disappeared, and a good mirror surface state was obtained.

On the other hand, the sintered bodies C and D containing the iron powder and the niobium powder are almost the same as the sintered bodies F and G after the sintering, but needle-like martensite is generated from the quenching temperature of about 800 ° C. At the quenching temperatures of 900 ° C. and 950 ° C., most of the precipitates were acicular martensite and residual β structure, and unevenness due to polishing was eliminated, and a good mirror surface condition was obtained. On the other hand, at 1000 ° C., the grain size was coarsened and the specularity was a little poor. With regard to the sintered body E, martensite begins to precipitate from the quenching temperature of about 850 ° C.
Satisfactory specularity was finally obtained at ℃.

From these results, the quenching temperature is 900-
1000 ° C., preferably 900 to 950 ° C.
It turned out that this is the condition that gives the best specularity. From the results of Examples 1 and 2, titanium powder was mixed with 1 to 3% by weight of iron powder and 9 to 10% by weight of niobium powder (corresponding to component D) and sintered at 1300 to 1400 ° C. , 9 more
By carrying out the quenching treatment at 00 ° C to 950 ° C, a titanium alloy having high specularity and scratch resistance can be obtained.

[0019]

According to the present invention, in order to solve the problems in the conventional powder metallurgy of titanium and titanium alloy, titanium powder is mixed with 1 to 3% by weight of iron powder and 9 to 10% by weight of niobium powder. After that, it is sintered at 1300 ° C to 1400 ° C, molded in this relatively workable state, heated at 900 ° C to 950 ° C, and then rapidly cooled to increase the hardness. It was possible to obtain a titanium alloy having high, light weight, good biocompatibility, good corrosion resistance, and high specularity and scratch resistance.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing relative densities of a green compact of the present invention before and after sintering.

FIG. 2 is an explanatory diagram showing hardness before and after quenching of the powder compact of the present invention.

Claims (3)

[Claims] 1. Titanium with 1 to 3% by weight of iron and 9 to
A decorative titanium alloy containing 10% niobium. 2. The decorative titanium alloy according to claim 1, which is subjected to a quenching treatment of quenching from a temperature of 900 to 950 ° C. 3. A powder obtained by mixing 1 to 3% by weight of iron powder and 9 to 10% by weight of niobium powder with titanium powder, and sintering the powder at 1300 to 1400 ° C. after compacting. A method for producing a decorative titanium alloy according to claim 1.