JPH02250951A - Method for hardening titanium material - Google Patents

Abstract

PURPOSE:To deeply harden the surface of the Ti material in a short time by heating a Ti material mounted with Ni in vacuum or in an inert atmosphere the eutectic point or above of both elements, diffusing the Ti material into Ni and thereafter executing hardening. CONSTITUTION:The surface of a Ti material is mounted with the sheet, powder or the like of Ni, which is heated in vacuum or in an inert atmosphere to the eutectic temp. (942 deg.C) or above of Ti and Ni to produce a liquid phase of Ti and Ni and joining is executed. Ni is successively diffused into the Ti material, which is thereafter hardened from the temp. of 765 to 1300 deg.C, preferably near 962 deg.C. In this way, the optional part in the Ti material, e.g. in the Ti sheet is hardened to about 400 to 600Hv. Since in the method, means of plating and thermal spraying having the need for complicated pretreatment are not used, hardening treatment can easily be executed at low cost in a short time.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for hardening titanium or titanium alloy materials (hereinafter simply referred to as titanium materials). It can be particularly advantageously applied when it is necessary to uniformly harden the plate.

(Conventional technology) Until now, oxidation method,
Nitriding method, ion blasting such as TiN, hard Cr
Although plating and the like are known, this is an extremely shallow surface hardening method of several micrometers to several tens of micrometers. Also, JP-A-56-816
No. 65 and Japanese Unexamined Patent Publication No. 58-91165 disclose Ni
A method has been proposed in which Ni is attached to a titanium material by plating or Ni thermal spraying, heated to 800 to 950°C, diffused, and then cooled with water, but this method has the disadvantage of requiring complicated pretreatment.

(Problem to be solved by the invention) In the hardening method of titanium materials, the hardened layer obtained by oxidation method and nitriding method is very brittle and weak against impact, and ion blating of TiN etc. cannot obtain a thick hardened layer. In the hard Cr plating method, there is a problem in waste liquid treatment. Also, JP-A-56-8
1665 and Japanese Patent Application Laid-open No. 58-91165, when a relatively thick hardened layer is required, the method of adhering by Ni thermal spraying is expensive, as seen in the examples, and the 50-Ni It takes a long time to apply thick plating.

Furthermore, in order to obtain a hardened layer with a hardness of 100%, it requires several hundred hours of heating time, which poses a problem in terms of productivity.

(Means for Solving the Problems) The inventor simply placed any one of Ni, Co, or Fe on a titanium material in a vacuum or an inert atmosphere,
It has been found that these metals can be easily bonded to titanium by heating at a temperature equal to or higher than the eutectic point of each of these metals and titanium. It was also confirmed that by diffusing each of these metals into titanium and then quenching it at a temperature above the eutectoid point, the material is hardened as it is, and if necessary, it is further hardened by aging.

That is, the gist of the present invention is as follows.

(1) Place Ni on the surface of a titanium material and heat it in vacuum or in an inert atmosphere at a temperature higher than the eutectic temperature of titanium and NiO.
After heating to 300°C or less to create a liquid phase of titanium and Ni and joining them, and then diffusing Ni into the titanium material,
A method for hardening titanium material, characterized by quenching and hardening at a temperature of 65°C or higher and 1300°C or lower.

Law.

(2) Place Fe on the surface of the titanium material, and heat it at 130° C. above the eutectic temperature of titanium and Fe in a vacuum or inert atmosphere.
After heating to below 0°C to create a liquid phase of titanium and Fe and bonding, and then diffusing Fe into the titanium material, 595
Method for hardening titanium material characterized by quenching and hardening at a temperature of 1300°C or higher (3) Co is placed on the surface of titanium material, and titanium and Co are bonded in vacuum or in an inert atmosphere Above the eutectic temperature of 1
After heating to 300°C or less to create a liquid phase of titanium and Co and bonding, and then diffusing Co into the titanium material, 6
A method for curing titanium material, characterized by quenching and hardening at a temperature of 85°C or higher and 1300°C or lower. The method of curing titanium material described.

(for production) The present invention will be explained in more detail below.

First, temporary or powder of Ni, Fe, or Co is placed on the surface of a titanium material, and these metals and the titanium material are liquid-phase bonded by heating to a temperature higher than the eutectic temperature.

The reasons why Nt'', Fe, and Co were used here are that titanium materials containing these can be hardened by quenching, that their diffusion coefficient in titanium is larger than that of other elements, and that they are There are three points: the eutectic temperature with these metals is relatively low.

Then titanium and Ni in vacuum or in an inert atmosphere.

It is heated to a temperature above the eutectic temperature with Fe or Co and below 1300° C. to form a liquid phase between titanium and these metals and join them.

The reason for heating in vacuum or in an inert atmosphere is that if the titanium material and the surfaces of Ni, Fe, or Co are not heated in such an atmosphere, the surfaces of the titanium material and Ni, Fe, or Co will be oxidized, and the bonding will not occur even if the two are at or above the eutectic temperature. This is to prevent it from happening.

Here, the eutectic temperature of titanium and Ni is 942°C, the eutectic temperature of titanium and Fe is 1085°C, and the eutectic temperature of titanium and Go is 1020°C.

The reason why the heating temperature was specified to be 1300° C. or lower is that if the temperature exceeds this temperature, titanium is likely to react, and a special method of holding it is required.

According to the present invention, when Ni is diffused into titanium material, 7
It is hardened by quenching at a temperature of 65°C or higher and 1300°C or lower. Here, the reason why the temperature is 765° C. or higher is that if the temperature is lower than this, sufficient residual β phase cannot be obtained and sufficient hardness cannot be achieved. In this case, a temperature around 942° C. is preferable. This is because at this temperature, the β single phase region in the Ni diffusion layer reaches its maximum thickness, and the cured thickness can be maximized. Here, 130
The reason why the temperature is set to be 0° C. or lower is that titanium tends to react at temperatures exceeding this temperature, and special measures are required to maintain the temperature.

Further, when Fe is diffused into the titanium material according to the present invention, it is hardened by quenching at a temperature of 595° C. or higher and 1300° C. or lower. Here, the reason why the temperature is 595°C or higher is that if the temperature is lower than this, sufficient residual β phase cannot be obtained and sufficient hardness cannot be achieved. In this case, a temperature around 1085°C is preferable. The reason for this is that at this temperature, the β single phase region in the Fe diffusion layer reaches its maximum thickness, and the cured thickness can be maximized.

The reason why the temperature is set to 1300° C. or lower is that at temperatures exceeding this temperature, titanium tends to react, and a special method of holding it is required.

Furthermore, when Co is diffused into the titanium material according to the present invention, it is hardened by quenching at a temperature of 685° C. or higher and 1300° C. or lower. The reason why the temperature is set at 685°C or higher is that if the temperature is lower than this, sufficient residual β phase cannot be obtained and sufficient hardness cannot be achieved. In this case, a temperature around 1020° C. is preferable. The reason for this is that at this temperature, the β single phase region in the Co diffusion layer reaches its maximum thickness, and the cured thickness can be maximized. The reason why the temperature is set at 1300° C. or lower is that titanium tends to react at temperatures exceeding this temperature, and a special method of holding the titanium is required.

The titanium thus hardened can then be further hardened by aging, if necessary.

For example, when 5 wt% Ni was diffused into a Ti-6Af-4V titanium alloy using the method according to the present invention, the hardness was 54011V when water-cooled from 970°C.
When this water-cooled material was further aged at 450° C. for 5 hours, the hardness became 600)1v. Furthermore, when 5 wt% of Fe is diffused into pure titanium material by the method according to the present invention, the temperature is 970°C.
The hardness was 410Hv while water-cooled, but
This water-cooled material aged at 400° C. for 1 hour had a hardness of 600 Hv. Additionally, 10t+ of Co is added to pure titanium material.
When diffused by t%, if water-cooled from 970℃, 3
The hardness was 50 Hv, but after further aging at 450°C for 5 hours, the hardness became 480 Hv.

In addition, according to the present invention, although the structure of the titanium material becomes coarse, a sufficiently thick hardened layer can be obtained, so after adjusting the structure by processing recrystallization, quenching may be performed, and aging may be performed if necessary. I can do it.

Incidentally, the quenching may be carried out by either ordinary water-cooling or oil-cooling method.

The present invention will be explained based on examples.

(Example 1) Ni powder (industrial purity) was placed on the surface of a hot-rolled pure titanium plate (equivalent to JIS Class 2) with a thickness of 3ffII11 to a thickness of 0.2M, and heated at 1000°C for 4 hours in a vacuum. After heating, the mixture was cooled in the furnace. Subsequently, it was heated in the air at 1000°C for 5 minutes and then cooled with water.

Next, the surface was polished by 0.5 mm to obtain a surface hardened mirror plate. Figure 1 shows the hardness distribution in the cross section of this plate.

In this way, it was possible to form a layer about 0.3 mm thick with a hardness of 500 Hv or more on the surface of the pure titanium hot-rolled sheet.

(Example 2) A 0.05 mm thick Ni foil (industrial purity) was placed on the surface of a cold-rolled pure titanium plate (equivalent to JIS Class 2) with a thickness of 1.0 mm.
was placed, heated in vacuum at 1000°C for 16 hours, and then cooled in the furnace. Subsequently, the mixture was heated in the air at 1000° C. for 5 minutes, and then cooled with water.

The hardness distribution of the cross section of the plate thus obtained is shown in FIG.

In this way, a 10 mm thick layer containing about 10 wt % Ni could be uniformly formed over the entire surface of the cold rolled pure titanium plate.

(Example 3) Fe powder was placed on the surface of a pure titanium (equivalent to JIS Class 2) hot-rolled plate with a thickness of 6.0 mm to a thickness of 0.2 mm, and after heating in vacuum at 1150°C for 34 hours. Furnace cooled. This board 9
After heating to 00°C, it was forged to a thickness of 3 mm and cooled in air.

Figure 3 shows the hardness distribution in the cross section. Even by air cooling alone in this manner, a layer with a thickness of about 0.3 ff1m and a hardness of 500 Hv or more could be formed on the surface of the pure titanium hot-rolled plate after forging.

(Example 4) A 0.025 mm thick Fe foil was placed on the surface of a cold-rolled pure titanium plate (equivalent to JIS Class 2) with a plate thickness of 1.0ffIl11, heated in vacuum at 1150°C for 2 hours, and then cooled in a furnace. did. Subsequently, the mixture was heated in the air at 900° C. for 5 minutes, and then cooled with water. This temporary was made flat with a leveler and then aged at 400°C for 1 hour.

Figure 4 shows the cross-sectional hardness distribution of the plate before and after aging.

In this way, it was possible to obtain a cold-rolled pure titanium sheet having a hardness of about 400 Hv even when water-cooled, and a hardness of about 600 Hv after aging.

(Example 5) A Co foil with a thickness of 0.050 m was placed on the surface of a pure titanium (equivalent to JIS Class 2) cold-rolled plate with a thickness of 1.0 trm, and after heating at 1150°C for 2 hours in a vacuum, it was heated in a furnace. It got cold. After successively heating at 950° C. for 5 minutes in the air, the mixture was cooled with water. After flattening this plate with a leveler, it was aged at 450"C for 5 hours. The cross-sectional hardness distribution of the plate before and after aging is shown in Figure 5. As shown, the hardness is about 350Hv when water-cooled, and the hardness after aging. A board of about 470 flv could be obtained.

(Example 6) A 0.050 tma thick Ni foil was placed on the surface of a 1.2 mm thick Ti-6A7-4V type titanium alloy cold rolled plate, heated in vacuum at 1000°C for 4 hours, and then cooled in a furnace. did. Subsequently, the mixture was heated in the air at 950° C. for 5 minutes, and then cooled with water. After flattening this board with a leveler, it was aged at 450°C for 5 hours.
Figure 6 shows the cross-sectional hardness distribution of the plate before and after aging.

In this way, a surface-hardened Ti-6jV-4V titanium alloy plate having a hardness of about 450 Hv while water-cooled and a hardness of about 640 Hv after aging was obtained.

(Effects of the Invention) According to the present invention, it is possible to make any part of a titanium material, for example, a titanium plate, to a hardness of approximately 400Hv to 600Hv, and it is also possible to make the hardness of a titanium material, such as a titanium plate, approximately 400Hv to 600Hv. Since this method does not require the use of other means, it is simple and inexpensive, and since high-temperature heating is applied, the curing process can be carried out in a short time, which is an excellent industrial effect.

[Brief explanation of drawings]

FIGS. 1 to 6 are diagrams showing changes in hardness in the depth direction of titanium materials treated in Examples 1 to 6. g:! (mm) Figure 2 Figure 3 Figure 5

Claims (4)

[Claims] (1) Place Ni on the surface of a titanium material, and heat it at 130° C. above the eutectic temperature of titanium and Ni in a vacuum or inert atmosphere.
After heating to below 0°C to create a liquid phase of titanium and Ni and bonding, and then diffusing Ni into the titanium material, 765
A method for hardening a titanium material, characterized by quenching and hardening at a temperature of 1300°C or higher. (2) Place Fe on the surface of the titanium material, and heat it at 130° C. above the eutectic temperature of titanium and Fe in a vacuum or inert atmosphere.
After heating to below 0°C to create a liquid phase of titanium and Fe and bonding, and then diffusing Fe into the titanium material, 595
A method for hardening a titanium material, characterized by quenching and hardening at a temperature of 1300°C or higher. (3) Co is placed on the surface of the titanium material, and the eutectic temperature of titanium and Co is exceeded at 130° C.
After heating to below 0°C to create a liquid phase of titanium and Co and bonding, and then diffusing Co into the titanium material, 685
A method for hardening a titanium material, characterized by quenching and hardening at a temperature of 1300°C or higher. (4) The method for curing titanium material according to any one of claims 1 to 3, characterized in that the titanium material is hardened by aging treatment after quenching.