ES2261754T3 - ALLOY OF BETA-TITANIUM METAESTABLE. - Google Patents

Abstract

Metastable beta -titanium alloy contains, in mass %: from 1.5 to 3.5 aluminum; from 4.5 to 8.0 molybdenum; from 1.0 to 3.5 vanadium; from 1.5 to 3.8 iron; titanium balance. This alloy combines high strength and ductility. This allows to use it for production of a wide range of critical parts including fastener components and different coil springs (e.g. in automobile industry).

Description

Β-Titanium Alloy metastable

Field of the Invention

This invention relates to metallurgy not ferric, and in more detail to the development of new alloys to titanium base that combine high strength properties and Ductility using relatively cheap alloy elements. The Alloys of this invention can be applied in a wide product range especially closures and different springs helical

Prior art

One of the known titanium alloys is the alloy containing (% by mass): 2-6 Al; 6-9 Mo; 1-3 V; 0.5-2 Cr; 0-1.5 Faith; Ti rest. Ref: USSR Certificate of inventor no. 180351, Class C22C 14 / 00,1966.

However, this alloy has a ductility insufficient due to the high content of Al and the presence of Cr. In addition this alloy is rather expensive. The other titanium alloy known contains (% by mass): 4-6.3 Al; 4.5-5.9V; 4.5-5.9 Mo; 2.0-3.6 Cr; 0.2-0.5 Fe; Ti rest. Ref: RF Patent No. 2169204, Class C22C 14/00, published 2001.

Said alloy when heat treated It has high strength properties in section slabs hard, but its ductility is insufficient so the alloy does not It can be used for the production of such parts as coil springs.

The alloy closest to the invention claimed is the β-titanium alloy metastable containing (mass%): 4-5 Fe; 4-7 Mo; 1-2 Al; O2 up to 0.25; Ti rest. Ref: US Patent No. 5,294,267, Class C22C 14/00, published 1994. This alloy will be the prototype. US Pat. No. 3,615,378 exposes a beta-titanium alloy high strength metastable with good ductility, which contains one of Fe, Mn, Cr and Co as beta eutectoid element and a content of V of 4-9% atomic.

This alloy has high machinability, it requires relatively low costs and is widely used for production of helical cylindrical springs in the industry car.

However, said alloy has properties of low ductility, especially elongation, which reduces the application of this alloy and is important in the production of some types of coil springs and components of closures.

The object of this invention is to provide a titanium alloy that combines high ductility and properties in heat treatment conditions that can be produced using cheap alloy elements.

According to the invention this is achieved by addition vanadium to β-titanium alloy metastable containing aluminum, molybdenum and iron with the following component content (mass%):

Aluminum 1.5-3.5 Molybdenum 4.5-8.0 Vanadium 1.0-3.5 Iron 1.5-3.8 Titanium rest

The addition of 1.0-3.5% of Vanadium increases the ductility of the alloy as required.

To achieve high resistance properties This alloy has a higher aluminum content than the prototype. Aluminum content less than 3.5% does not influence significantly on the ductility of the alloy. The content of aluminum greater than 3.5% and iron greater than 3.8% increases the amount of phase a, causes hardening and reduces ductility less than desired The lower iron content (<4%) than in the prototype ensures greater phase stability during thermal cycles, (deformation and heat treatment). The desired resistance properties cannot be achieved with aluminum below 1.5%. Molybdenum content below 4.5% and iron below 1.5% reduces the amount of phase β and does not allow to achieve high alloy strength heat treated.

The increase in the content of this type of β stabilizers such as molybdenum and vanadium exceeding specified limits reduces the stability of the alloy by hardened and aged conditions and increases grain size during heat treatment, which significantly reduces the alloy ductility - (β <4%; and \ Psi <7%).

Molybdenum is added as ferromolibdene with 55-75% molybdenum and iron rest.

Vanadium is added as ferrovanadium with 65-85% vanadium and rest of iron or remains of Ti-Al-V system manufactures.

Embodiments of the invention

To study the properties of the alloy, we melted ingots with the composition shown in table 1 in a vacuum arc furnace and 20 mm diameter bars were made of these ingots. The bars were heat treated under the following conditions: heating at a temperature of 30 ° C by below the temperature of beta transus, water cooling, heating at 480 ° C for 8 hours, air cooling. The tensile samples were then evaluated according to ASTM E 8.

Table 2 shows the properties mechanics of the bars produced from the alloys rated.

TABLE 1

Content of elements (% by weight) Example To the Mo V Faith You one 1.5 4,5 1.0 1.5 rest 2 2.5 5.5 2.0 2.5 rest 3 3.0 6.5 3.0 3.5 rest 4 3.5 8.0 3.5 3.8 rest

TABLE 2

Mechanical properties Example Definitive Resistance, Resistance to Elongation Reduction from \ sigma_ {B} MPa conformation, \delta, % Area \Psi,% \ sigma_ {o, 2}. MPa one 1100 1020 - 25.1 58.7 2 1250 1190 20.2 46.4 3 1440 1390 6.1 10.2 4 1520 1480 4.9 7.3

Commercial Practicability

Β-titanium alloy claimed metastable compared to alloys known has the specified optimal combination of elements of Alloy alpha and beta stabilizers, which ensures high strength and ductility of the heat treated alloy. This one is cheap and It can be used for the production of a wide range of parts fundamental, particularly components of closures and springs different helical

Claims (1)

1. β-titanium alloy metastable, containing aluminum, molybdenum and iron, containing additionally vanadium, in the following content of components (% mass): Aluminum 1.5-3.5 Molybdenum 4.5-8.0 Vanadium 1.0-3.5 Iron 1.5-3.8 Titanium rest