JP2751776B2 - Titanium alloy cladding powder with excellent seawater resistance and wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cladding powder for forming a hardfacing layer having excellent seawater resistance and abrasion resistance formed on the surface of a Ti or Ti alloy member. Since the titanium alloy member provided with the hardfacing layer obtained by using the cladding powder according to the present invention exhibits excellent seawater resistance and abrasion resistance, it can be used for a seawater intake port or the like. it can.

[0002]

2. Description of the Related Art Titanium alloy is known as a material exhibiting excellent corrosion resistance against corrosion by seawater. However, it has been pointed out that a disadvantage is that it is severely worn in an actual use environment and cannot be used for a long time. I have.

Meanwhile, as a method of improving the wear resistance of a Ti alloy, Ni-P has been conventionally used by plating, CVD, PVD or the like.
A method of adhering a coating, a TiN, or a TiC hard coating on the surface is known, but they do not exert much effect under severe conditions in which metals slide and wear.

On the other hand, as a method of improving the wear resistance of a metal material, a cladding method is also known. For example, a hard cladding layer is formed on a Ti or Ti alloy by using Ti or Ti alloy powder and W ₂ C with a high energy beam. Is disclosed in Japanese Patent Laid-Open No. 2-1293.
Although disclosed in Japanese Unexamined Patent Publication No. 30, the use of W ₂ C
Is poor in seawater resistance, so that the high wear resistance shown in a dry environment is not exhibited in seawater.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a build-up powder for forming a hardened build-up layer which exhibits excellent corrosion resistance even in a seawater environment and resists metal wear.

[0006]

Means for Solving the Problems The present inventors have studied to solve the above-mentioned problems, and as a result, when tungsten carbide is dispersed in a Ti alloy matrix as described above, the seawater corrosion resistance of tungsten carbide itself is reduced. The seawater resistance of the hardfacing layer deteriorates due to the inferiority, but as a result of examining various additive elements to improve this seawater resistance,
1 to 10% by weight (2 to 20% by weight in the case of Cr ₃ C ₂ ), and if necessary, one or more of platinum group elements alone or in a total of 0.1
It has been found that the corrosion resistance can be improved without impairing the abrasion resistance by adding Ni and / or Co in a total amount of 0.1 to 6% by weight if added in an amount of 01 to 1.5 wt%.

That is, according to the findings of the present inventors, Ti-WC-Cr-based powder is particularly effective as a cladding material for titanium or a titanium alloy, and at least one of a platinum group element, Ni, and Co is used. By blending, the seawater resistance is further improved.

Accordingly, the gist of the present invention is that, in terms of% by weight, Ti or Ti alloy powder: 15 to 49% by weight, Cr powder:
1 to 10% by weight and / or Cr ₃ C ₂ powder: 2 to 20% by weight, and tungsten carbide powder: The balance is a titanium alloy overlay powder having excellent corrosion and wear resistance.

[0009] The titanium alloy overlay powder further contains a platinum group element powder, the content of which is 0.01 to 10% of the total powder.
1.5% by weight and / or the titanium alloy cladding powder comprises Ni powder and / or Co powder,
Its total content may be from 0.1 to 6% by weight, based on the total powder.

[0010]

Next, the reason why the powder composition for overlaying in the present invention is limited as described above will be described. In this specification, “%” is “% by weight” unless otherwise specified.

[0011] Ti or Ti alloy powder: plays a role of a binder at the time of hardfacing on Ti or Ti alloy. If less than 15%, the binder effect is insufficient, so the minimum required amount is 15%. did. The reason why the upper limit is set to 49% is that, as will be described later, sufficient hardness as a hardfacing layer is W ₂ C amount, preferably 50% or more is blended. Since the Cr content is required to be 1% or more, the upper limit is set to 49%.

The type of the Ti alloy for providing the hardfacing layer is not particularly limited, and may be a pure titanium material or any titanium alloy material. Examples of these alloys include (α + β) type Ti-6Al-4V, Ti-3Al-2.5V, etc.
Ti alloy, Ti-15V-3Al-3Sn-3Cr, Ti-10V-2Fe-3Al, Ti-3Al
Β-type Ti alloys such as -8V-6Cr-4Zr-4Mo.

Cr powder and / or Cr ₃ C ₂ powder: Cr is
When added in the form of chromium metal or Cr ₃ C ₂ , it exists as solid solution Cr in the hardfacing layer, which has the effect of promoting passivation of titanium.

Cr powder: The effect of adding Cr powder is 1% by weight.
% Is effective. However, the addition exceeding 10% has the effect of lowering the toughness, and the addition amount is 1%.
~ 10% is good. Preferably, it is 3 to 7%.

Cr ₃ C ₂ powder: When Cr ₃ C ₂ is overlaid, Cr becomes T
i dissolves in the matrix and C precipitates as TiC.
The dissolved Cr has the effect of promoting the passivation of titanium. The effect is exhibited by the addition of 2% or more of Cr ₃ C ₂ . However, the addition exceeding 20% has the effect of reducing toughness, and 2 to 20% is good. More preferably, it is 5 to 12%.

Tungsten carbide powder: High melting point among various carbides, undissolved and can be dispersed in a large amount in Ti alloy matrix, and high abrasion resistance can be obtained. Used.
Tungsten carbide is a substance having a low coefficient of wear by itself, and can reduce the frictional force with the sliding metal. For example, a bearing sleeve is a component that requires extremely high wear resistance.

Therefore, in the present invention, the tungsten carbide powder occupies the remainder, but in order to sufficiently exhibit the above-described characteristics, the dispersion amount of tungsten carbide is desirably 50% or more. However, if it exceeds 75%, the toughness of the hardfacing layer deteriorates, so the preferred composition is 50 to 75%.

As tungsten carbide, from WC
W ₂ C has better wear resistance, and when a part of it is dissolved in the Ti alloy matrix, W ₂ C has a lower C content, so the amount of C that forms a solid solution with the newly precipitated and / or precipitated titanium carbide W ₂ C is preferred from the viewpoint of toughness because it is less. The generated titanium carbide is useful for improving wear resistance.

Although the solid solution tungsten makes the matrix βTi to further improve the wear resistance, even if the solid solution amount is small and the (α + β) Ti phase is formed, a large amount of dispersed tungsten carbide causes wear resistance. Sex is fully exhibited. Further, in another embodiment of the present invention, seawater resistance is further improved by adding a powder of a platinum group element, or Ni and / or Co.

Platinum group element powder (eg, Os, Ir, Rh, Pt,
Au, Pd, Ru): These elements have the effect of lowering the hydrogen overvoltage and passivating the titanium alloy matrix, and the effect is exhibited when the total content is 0.01% or more. Even if added over 1.5%, the effect saturates and leads to unnecessarily high prices.
01-1.5%. Preferably, it is 0.2-0.8%.

Ni powder and / or Co powder: These elements, like the platinum group elements, have the effect of lowering the hydrogen overvoltage to passivate the titanium alloy matrix. Not big. This effect is particularly exhibited by the simultaneous addition of Cr and a platinum group element, and the total content is preferably 0.1 to 6%. Addition of more than 6% is not preferable because it reduces toughness.

Next, regarding the form, size, and compounding form of these powders, for example, the particle size is not particularly limited, and may be any as long as it can be overlaid with a so-called high energy beam. However, it is preferably as follows.

First, as the Ti alloy powder, αTi, (α + β) Ti, βTi alloy powder whose shape is made polygonal by a hydrogenated Ti pulverization method and whose particle size range is adjusted to 60 to 250 mesh can be used. The amount of oxygen at this time is preferably 0.15 to 1% by weight. If the amount of oxygen is too large, the toughness of the built-up portion deteriorates. Al to pure Ti powder
-V master alloy powder or the like may be mixed and used as the elementary powder.
If only pure Ti powder is used, the hardness of the built-up portion may be reduced. Therefore, it is preferable to use alloy powder.

For example, Ti-6Al-4V, Ti-3Al
(Α + β) type Ti alloy such as -2.5V, Ti-15V-3Al-3Sn-3Cr,
There are β-type Ti alloys such as Ti-10V-2Fe-3Al and Ti-3Al-8V-6Cr-4Zr-4Mo. Ti-15V-3Al-3Sn-3Cr and Ti-3Al-8V-6Cr-4Zr-
When a Cr-containing alloy powder such as 4Mo is used, the amount of the Cr powder or Cr ₃ C ₂ powder needs to be reduced by the amount of Cr in the alloy.

The method of forming the surface hardened build-up layer is to mix Ti or Ti alloy powder of about 60 to 350 mesh, tungsten carbide powder, chromium carbide, a platinum group element, Ni, Cr and Co powder, What is necessary is just to build up while melting a base material and a mixed powder using a high energy beam. PTA method, TIG method
Method, laser beam method, electron beam method, etc., but PTA
The method is the easiest to use.

The same effect can be obtained by adding the platinum group element, Ni, Co and the like in the form of an alloy element when preparing the above-mentioned Ti alloy powder without adding it in the form of respective powders.
The thickness of the build-up layer is preferably about 1 to 3 mm, but is not particularly limited. After the build-up, it may be processed into a desired shape as needed. Next, the operation of the present invention will be described more specifically with reference to examples.

[0027]

[Embodiments] In each case, hydrogenated Ti and hydrogenated Ti alloy powder (80 ~
200 mesh) and the chromium powder, chromium carbide powder and tugsten carbide powder shown in Tables 1 and 2.
(Tables 1 and 2) using pure metal powders of Ni and Co (both 80 to 250 mesh).
The mixture was adjusted to the mixing ratio shown in Table 2 and was overlaid on the surface of a Ti-6Al-4V alloy rod having a diameter of 100 mm x 40 mm by the PTA method to form a hardened overlaid layer having a thickness of 3 mm.

The build-up conditions were a current of 170 A, a voltage of 35 V, a welding speed of 200 mm / min, a shield Ar amount of 15 l / min, a plasma Ar gas of 3 l / min, a powder supply of 6 cc / min, a carrier Ar gas of 2 l / min. Minutes. For comparison, the same PTA method was used, and a [Ni + tungsten carbide] mixed powder was overlaid on the surface of a SUS316L stainless steel alloy rod having a diameter of 100 mm and a length of 40 mm.

Next, 10 mm in diameter × 40 m in length including the hardened surface from these surface-hardened bars (100 mm in diameter).
After cutting out the abrasion test piece of m and polishing the test surface,
According to the test procedure shown in Table 3, under the test conditions shown in Table 3, a pin was inserted between the SiC disk surface 10 and the test piece (pin) 14 having the hardfacing layer 12 while flowing 3.5% saline in a seawater environment. An on-disk test was performed. The pressing load was 10 kg. A wear amount of 15 mg or less was judged to be acceptable.

Further, the diameter is 15 mm × 2 m in thickness from the built-up portion.
An m 2 polarization test piece was cut out, anodically polarized at a potential sweep rate of 20 mV / min in degassed artificial seawater at 25 ° C., the pitting potential was measured, and the effect of improving seawater resistance was examined. The potential at which the current density became 50 μA / cm ² was defined as the pitting potential. The pitting potential is required to be at least 0.5 V (vsSCE), but the higher, the better.

The results are also summarized in Tables 1 and 2. In addition, in the same table, the term "build-up layer crack" means that the crack has occurred due to the large amount of the mixed carbide. Table 1 and Table 2
The following is clear from the results shown in FIG. The hardfacing layer according to the present invention (Inventive Examples 1 to 29) has excellent abrasion resistance and seawater resistance simultaneously in a seawater environment, and has good properties as a corrosion-resistant wear-resistant member in high-speed seawater. Is shown.

Comparative Examples 1 and 2 are build-up examples exhibiting abrasion resistance under dry conditions. However, since they do not contain Cr, they are inferior in seawater resistance and have insufficient wear and pitting potential. High performance. However, as shown in Invention Example 1, 1% of Cr
When added, the seawater resistance is significantly improved, the wear is reduced and the pitting potential is above the required 0.5 V. Comparative Example 5 shows that seawater resistance is not sufficient when Cr: 0.5%.
Comparative Example 8 shows that 1% of Cr ₂ C ₃ is not enough. Cr
When the amount of addition was increased, the abrasion resistance in a dry environment decreased, but in a seawater environment, the addition of Cr improved the seawater resistance, so the amount of abrasion in seawater did not increase significantly.

Similar effects were observed when the metal Cr powder was replaced with chromium carbide powder or when both were used in combination (Inventive Examples 4, 5, and 6). When more than 10% of Cr was added, cracks occurred in the overlay (Comparative Example 6), and when more than 20% of Cr ₂ C ₃ was added, similar cracks occurred (Comparative Example 9).

When Cr and a platinum group element are added simultaneously, the pitting potential becomes 2 V or more, and the seawater resistance is improved. The effect is exhibited by the addition amount of 0.02% (Invention Example 7). Also, as can be seen from a comparison between Invention Example 16 and Comparative Example 10,
When Pd is added in an amount of 1.4%, the effect of improving seawater resistance is saturated, and even if Pd is added further, the material price will rise.

When a platinum group element and Ni or Co are added simultaneously, the effect of improving seawater resistance is exhibited, as can be seen from a comparison between Invention Examples 7 or 9 and 11 or 14. In addition, Invention Example 20
From the comparison with Comparative Example 11, it can be seen that excessive addition of Ni causes cracks in the build-up layer. The same can be said for Co addition.

Inventive Examples 22 to 25 are examples in which titanium powder is pure titanium, and Inventive Examples 26 to 29 are Ti-3Al-8 which is a β-type alloy.
Although the example using the powder of 0-6Cr-4Zr-4Mo was shown, the same effect of improving the seawater resistance was exhibited, so that the use of any titanium alloy powder has the same effect. confirmed.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

According to the present invention, a titanium or titanium alloy member having excellent abrasion resistance and seawater resistance for seawater can be industrially supplied, and conventionally must be replaced in a short time. Can be used for a longer period of time than Ni + tungsten carbide
The industrial value is great.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a procedure of a wear test in a seawater environment.

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 35/32 B23K 9/04 B23K 10/02

Claims (3)

(57) [Claims] 1% by weight of Ti or Ti alloy powder: 15 to 49% by weight, Cr powder: 1 to 10% by weight and / or Cr ₃ C ₂ powder: 2 to
20% by weight and tungsten carbide powder: Titanium alloy cladding powder consisting of the balance and having excellent seawater resistance and wear resistance. 2. The composition according to claim 1, wherein said content is equal to 0.
The powder for overlaying titanium alloy having excellent seawater resistance and abrasion resistance according to claim 1, characterized in that the powder contains 01 to 1.5% by weight of a platinum group element powder. 3. The seawater resistant composition according to claim 1, further comprising a Ni powder and / or a Co powder having a total content of 0.1 to 6% by weight based on the total powder. Titanium alloy overlay powder with excellent wear resistance.