JPH11222642A - Titanium alloy excellent in wear resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Ti alloy free from the need of executing wear resisting surface treatment such as nitriding, oxidizing, build-up welding or the like and having good wear resistance in the case of being applied to sliding parts or the like. SOLUTION: This Ti alloy has a compsn. contg., by weight, 2 to 6% Al, 18 to 30% V, 0.1 to 4.0% Si, and the balance substantially Ti. If required, one or >= two kinds among Fe, Cr, Ni, Co and Mn are furthermore incorporated therein in the range of <=2%. Moreover, the content of O is regulated to 0.18%, that of N to <=0.03% and that of C to <=0.03% when occasion demands.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Ti alloy suitable for a member requiring wear resistance, such as a valve spring retainer, a valve spring, and a golf club head.

[0002]

2. Description of the Related Art Ti alloys are light and strong, have excellent corrosion resistance, and have been used mainly as space aviation materials. Recently, it has also been used as a material for automobiles, a material for mechanical structural parts, a material for general private demand, and the like.

[0003] Ti alloys are α-type alloys and α-type alloys at room temperature.
+ Β-type alloys and β-type alloys. Conventionally, mechanical properties are stable, and α + β
Type Ti-6Al-4V alloy has been used most often.

[0004] This Ti-6Al-4V alloy is a highly reliable alloy supported by many achievements, but has poor plastic workability and is difficult to cold work. Therefore, the product is mainly manufactured by cutting. It was manufactured, and as a result, the material yield was low, and this was a factor that increased the product cost.

Therefore, β of a body-centered cubic crystal having good plastic workability
Expectations for a phase-based β-type Ti alloy have increased, and various research and development have been promoted. In the case of this β-type Ti alloy, quenching (solution treatment) is performed from a high temperature (generally, cold working is performed after the solution treatment), and then tempering (aging) is performed, so that the fine phase of α phase etc. A precipitated phase can be precipitated to improve the strength.

However, the conventional Ti alloy has a problem in that the wear resistance is poor, and when it is applied to a sliding portion, a wear-resistant surface treatment such as nitriding, oxidation, or overlaying is indispensable.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a Ti alloy capable of obtaining good wear resistance without such a wear-resistant surface treatment, that is, a Ti alloy having excellent wear resistance. The purpose is to provide. Thus, the Ti alloy of the present invention, which has excellent wear resistance, has Al: 2 to 6% and V: 1 by weight.
8 to 30%, Si: 0.1 to 4.0%, balance substantially T
i.

[0008] The Ti alloy according to claim 2 is, by weight%, Al:
2 to 6%, V: 18 to 30%, Si: 0.1 to 4.0
%, And one or more of Fe, Cr, Ni, Co, and Mn in a total amount of 2% or less.

The Ti alloy according to claim 3 is the method according to claim 1 or 2, wherein O: ≦ 0.18%, N: ≦ 0.03%, C: ≦
It is characterized by being regulated to 0.03%.

[0010]

As described above, in the present invention, a predetermined amount of Si is contained in a β-phase-based Ti alloy. In the case of this Ti alloy, silicide (intermetallic compound of Si and Ti) is used. The wear resistance can be effectively improved by the precipitation of Ti ₅ Si ₃ ).

Therefore, it is not necessary to apply a wear-resistant surface treatment such as nitriding treatment, oxidation treatment, overlaying treatment or the like when applied to sliding parts as in the prior art. Cost can be reduced.

Next, the reasons for limiting each chemical component in the present invention will be described in detail. Al: 2 to 6% Al is an element for solid solution strengthening of the α phase, and in a β-type Ti alloy, has the function of suppressing the generation of the ω phase, which becomes the embrittlement phase, and increasing the precipitation strengthening of the α phase. However, if the content is less than 2%, the effect is small, and if it exceeds 6%, other precipitated phases (Ti ₃ Al)
Is added to cause brittleness, so it is added in the range of 2 to 6%.

V: 18-30% V is added to stabilize the β phase at room temperature. The V amount required to bring the Ms point to room temperature is 15%, but it is necessary to secure about 18% industrially. Therefore, in the present invention, the lower limit of the added amount of V is set to 18%. On the other hand, if it exceeds 30%, the β phase becomes stable, and the treatment time for the aging treatment becomes longer, which is not practical. Therefore, the upper limit is specified as 30%.

Si: 0.1 to 4.0% Si is an essential element for improving the wear resistance of the Ti alloy in the present invention, and silicide (Ti ₅ ) which is an intermetallic compound of Si and Ti is added by adding Si. Si ₃ ) is dispersed and precipitated, and its precipitation effect improves abrasion resistance. However, if the content is less than 0.1%, the effect is small, and if it is added in a large amount exceeding 4.0%, eutectic reaction occurs between silicide and Ti in a cooling process to form a eutectic structure and embrittle. , And the ductility deteriorates. Therefore, in the present invention, the upper limit is defined as 4.0%.

Fe, Cr, Ni, Co, Mn: ≦ 2.0% These elements are elements that stabilize the β phase like V, and it is also effective to add them in a range of 2% or less. However, these elements are eutectoid elements, and if added in excess of 2%, they form intermetallic compounds and cause embrittlement, so the upper limit is set to 2.0%.

O: ≦ 0.18% In the Ti alloy of the present invention, the abrasion resistance is improved by the precipitation of silicide, but the toughness and ductility may be reduced.
Therefore, the content of O is regulated to a certain level or less. By adding O in a small amount, the strength of the Ti alloy can be increased,
If the content is more than 0.18% under the conditions in which silicide is precipitated, the toughness and ductility of the Ti alloy will decrease, so the upper limit is regulated to 0.18%.

N, C: ≦ 0.03% Normally, N and C are N: ≦ 0.05% and C: ≦ 0.0, respectively.
Although it is regulated to 8%, it is necessary to further regulate N and C under the condition where silicide is deposited. Therefore, in the present invention, these N and C are set to 0.0
Restrict to 3% or less.

[0018]

Next, embodiments of the present invention will be described in detail. Table 1
6 kg of a Ti alloy having the composition shown in Table 1 was melted in a plasma furnace to form an ingot having a diameter of 100 mm, and a test piece was cut out from the ingot and evaluated for wear resistance and ductility. In addition, a part was heat-treated under the conditions shown in Table 1, and the heat-treated product was evaluated for wear resistance and toughness.

[0019]

[Table 1]

The evaluation of toughness and ductility was made by elongation at break in a tensile test, and the evaluation of abrasion resistance was made by the following test. <Evaluation of abrasion resistance> Test method: Ogoshi type abrasion test Test conditions Counterpart material: SUJ2 ring Sliding distance: 200 m Sliding speed: 0.94 m / sec Lubricating oil: None Load: 6.3 kgf

The results are also shown in Table 1. As can be seen from the results in Table 1, in the case of the invention containing Al, V, and Si within the scope of the present invention, Comparative Example 2 containing no Si.
In each case, the abrasion resistance is significantly improved.
In the case of Comparative Example 1 containing more than 4% of Si, although the abrasion resistance is good, the value of the elongation at break is low due to the excessive content of Si.

On the other hand, in the case of the present invention containing 4% or less of Si, a certain or more toughness is secured.
Further, in Invention Examples 13 and 14 in which O, C, and N are all regulated to 0.18% or less, 0.03% or less, and 0.03% or less,
Despite the precipitation of silicide due to the addition of Si, the reduction in toughness is better suppressed, and good toughness is ensured.

Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be implemented in variously modified forms without departing from the gist thereof.

Claims (3)

[Claims] (1) Al: 2 to 6% by weight V: 18 to 30% Si: 0.1 to 4.0% The balance is substantially Ti, and Ti is excellent in wear resistance. alloy. 2. An Al content of 2 to 6% by weight V: 18 to 30% Si: 0.1 to 4.0% and at least one of Fe, Cr, Ni, Co and Mn
A Ti alloy excellent in abrasion resistance, characterized by containing at least 2 species in a total amount of 2% or less. 3. The T having excellent abrasion resistance according to claim 1, wherein O: ≦ 0.18% N: ≦ 0.03% C: ≦ 0.03%
i alloy.