RU2614355C1 - Titanium-based alloy and product made from it - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: titanium-based alloy contains, weight %: aluminium 6.0-8.0, molybdenum - 0.4-1.3, tin - 1.5-3.5, zirconium 1.0-5.0 , iron - 0.05-0.4, niobium - 0.4-1.4, silicon - 0.1-0.4, tantalum - 0.2-1.0, tungsten - 0.3-1.3, beryllium - 0.01-0.15, titanium - the rest.

EFFECT: alloy is characterized by high values of short-term strength.

2 cl, 2 tbl, 4 ex

Description

The invention relates to the field of non-ferrous metallurgy, namely, titanium alloys used for the manufacture of highly loaded parts and assemblies operating at temperatures up to 600 ° C, for example, for the manufacture of deformed semi-finished products in the form of disk and blade blanks for compressor parts of gas turbine engines (GTE).

From / RU 2039112 Cl, July 9, 1995 / a titanium-based alloy is known having the following chemical composition, wt. %:

aluminum 5.8-6.6 molybdenum 0.8-1.5 zirconium 2.0-4.0 iron 0.06-0.13 silicon 0.25-0.45 tin 2.5-4.5 niobium 0.8-2.5 oxygen 0.05-0.12 carbon 0.05-0.1 tungsten 0.35-0.8 titanium rest

The disadvantage of the alloy is a relatively low level of strength in the temperature range from 20 to 550 ° C and a narrow temperature range of pressure treatment in the two-phase region (≈100 ° C).

From / CN 101988167 A, 03/23/2010 / known alloy based on titanium having the following chemical composition, wt. %:

aluminum 6.2-6.5 zirconium 3.5-4.0 tin 2.0-2.5 molybdenum 0.1-0.3 niobium 0.6-0.9 silicon 0.3-0.4 neodymium 0.4-0.8 titanium rest

The disadvantage of the alloy is the low level of strength properties at room and elevated temperatures, the insufficient level of technological plasticity during pressure treatment, which limits the use of the alloy only to relatively large-sized forgings and stampings made by deformation at high temperatures.

The closest analogue in composition and purpose is an alloy based on titanium, disclosed in / RU 2507289 C1, 02/20/2014 /, which has the following chemical composition, wt. %:

aluminum 5.0-6.6 molybdenum 1.5-2.5 zirconium 1.0-2.8 vanadium 0.4-1.4 iron 0.08-0.40 silicon 0.08-0.28 tin 1,5-3,8 niobium 0.4-1.2 oxygen 0.02-0.18 carbon 0.008-0.080 titanium rest

The disadvantage of the prototype alloy is not a sufficiently high level of strength at room and elevated temperatures. A high level of ductility may indicate insufficiently high performance at elevated temperatures, including short-term and long-term strength at 600 ° C, which is associated with an insufficient degree of dispersion and solid solution hardening of α- and β-solid alloy solutions.

The technical result of the claimed invention is to increase the level of short-term strength of a titanium alloy at a temperature of 20 ° C by 4.0-7.5% and at 6000 ° C by 8.5-11.5% relative to the prototype while maintaining ductility at 20 ° C at a satisfactory level.

To achieve the technical result, an alloy based on titanium containing aluminum, molybdenum, tin, zirconium, iron, niobium, silicon is proposed, while it additionally contains tantalum, tungsten and beryllium in the following ratio of components, wt. %:

aluminum 6.0-8.0 molybdenum 0.4-1.3 tin 1,5-3,5 zirconium 1.0-5.0 iron 0.05-0.4 niobium 0.4-1.4 silicon 0.1-0.4 tantalum 0.2-1.0 tungsten 0.3-1.3 beryllium 0.01-0.15 titanium rest

Also proposed is a product made of this alloy.

To achieve a high level of a set of physicomechanical properties (strength, heat resistance, thermal stability and manufacturability), tantalum, tungsten and beryllium, which are β-stabilizers, were introduced into the alloy in the indicated amount. These elements increase the resistance of the alloy to oxidation, the temperature of recrystallization and have a modifying effect that increases the level of short-term strength at elevated temperatures.

The alloy contains close to the maximum possible amount of α-stabilizing alloying element (aluminum) and neutral hardeners (tin, zirconium) close to heat-resistant titanium alloys, which ensure its high thermal stability and heat resistance. A further increase in their amount in the alloy will inevitably lead to a decrease in thermal stability, and a decrease in their number will cause a drop in heat-resistant properties.

Alloying the alloy with β-stabilizers (molybdenum, niobium, tantalum, tungsten, iron) within the indicated limits makes it possible to increase the level of short-term strength at 20 ° C due to solid-solution hardening and to provide the necessary level of its technological plasticity during pressure treatment in the upper temperature range (α + β ) -regions.

Since heat-resistant alloys in most cases at a working temperature are characterized by a metastable phase composition, high-temperature diffusion and recrystallization processes play an important role for them. Suppressing or slowing down these processes improves not only the thermal stability of the alloy, but also its heat resistance and heat resistance. For this purpose, Ta and W are introduced into the alloy, which increase the recrystallization temperature by approximately 50 ° C and, therefore, inhibit the decomposition of metastable structures. In addition, tantalum, having a high affinity for oxygen, prevents its diffusion in the crystal lattice. Tantalum also increases the resistance of the alloy to penetrating oxidation.

Silicon in the specified amount allows you to implement both solid solution and dispersion hardening mechanisms due to the presence of silicides in the structure of the alloy. Due to their high thermal stability, silicides can increase the heat resistance of the alloy. With a lower silicon content, the amount of silicides is not enough to significantly increase the heat resistance, and when this amount is exceeded, too many large precipitates of silicides are formed, which reduce the ductility, manufacturability of the alloy and its long-term performance.

Beryllium microadditives provide a modifying effect on the alloy structure, which results in a finely dispersed and uniformly distributed structure in the bulk of the semi-finished product. The introduction of beryllium in smaller quantities does not have the necessary modifying effect. Adding more beryllium to the alloy is impractical, since in this case it will be necessary to provide special measures to organize production and protect personnel from its negative effects. Due to the very low solubility of beryllium in the α phase of titanium, the introduction of a large amount of beryllium into the alloy leads to the formation of a large number of intermetallic particles, which leads to embrittlement of the alloy and a decrease in its processability.

Examples of implementation

The proposed alloy and prototype alloy in the form of ingots were smelted by the triple vacuum-arc remelting method. Then, the ingots were subjected to deformation processing by upsetting and comprehensive forging in quasi-isothermal conditions on the suture. The resulting stoops were prepared for rolling by planing on all surfaces. After rolling and cutting into strips, they were deposited in quasi-isothermal conditions on profiled billets, which were subjected to final heat treatment and testing.

Table 1 shows the chemical composition of the smelted ingots.

Next, the following characteristics of the obtained semi-finished products were determined:

- the tensile strength and elongation of the samples at a temperature of 20 ° C were determined by conducting tensile tests in accordance with GOST 1497;

- the tensile strength and elongation of the samples at a temperature of 600 ° C were determined by conducting tensile tests in accordance with GOST 9651.

Table 2 shows the mechanical properties of the proposed alloy and prototype alloy.

As can be seen from table 2, in the proposed alloy compared to the prototype alloy, the level of tensile strength at a temperature of 20 ° C increased by 4.0-7.5% and at 600 ° C by 8.5-11.5% while maintaining ductility at 20 ° C at a satisfactory level.

The proposed alloy can be used as a heat-resistant material for the manufacture of parts (blades and disks) of the compressor of aircraft gas turbine engines, as well as parts of turbines of power engineering. The invention will improve the resource of parts and weight efficiency of engines of gas turbine engines due to a higher level of strength compared to analogs at a working temperature of up to 600 ° C.

Claims (3)

1. An alloy based on titanium containing aluminum, molybdenum, tin, zirconium, iron, niobium and silicon, characterized in that it additionally contains tantalum, tungsten and beryllium in the following ratio of components, wt. %: aluminum  6.0-8.0 molybdenum  0.4-1.3 tin  1,5-3,5 zirconium  1.0-5.0 iron  0.05-0.4 niobium  0.4-1.4 silicon  0.1-0.4 tantalum  0.2-1.0 tungsten  0.3-1.3 beryllium  0.01-0.15 titanium  rest 2. A product made of an alloy based on titanium, characterized in that it is made of an alloy according to claim 1.