RU2346998C2 - Alloy on titanium base and item made out of this alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: group of inventions refers to structural high strength welded titanium alloys designed for fabricating large-size power details and welded units of aircraft engineering. There is suggested an alloy on titanium base and an item made out of this alloy. The alloy contains components at the following ratio, wt %: aluminium - 4.3 -6.0, molybdenum - 4.0 - 5.6, vanadium - 4.0 - 5.6, chromium - 0.5 - 1.5, iron - 0.5 - 1.5, zirconium - 0.03 - 0.5, copper - 0.003 - 0.15, nickel - 0.003 - 0.15, oxygen - 0.02 - 0.2, carbon - 0.01 - 0.1, nitrogen - 0.01 - 0.05, hydrogen - 0.003 - 0.015, hafnium - 0.03 - 0.5, titanium - the rest. Total contents of oxygen, carbon and nitrogen in the alloy preferably meets the condition 0.15%≤[(%O)+0.5(%C)+1.7(%N)]≤0.24%.

EFFECT: upgrading low-cycle fatigue of welded units and thermal stability of the base metal.

3 cl, 2 tbl, 2 ex

Description

The invention relates to the development of structural high-strength weldable titanium alloys intended for the manufacture of large-sized power parts and welded components of aircraft: beams, spars, frames, power elements of the chassis structure and engine mounts used in aircraft.

Known alloy based on titanium of the following chemical composition, wt.%:

aluminum 5.5-6.75 molybdenum 0.85-3.15 vanadium 3.5-4.5 iron 0.85-3.15 oxygen ≤0.2 titanium rest

(Japanese application No. 02173234)

Known alloy has a reduced ductility.

Products made from it are not suitable for the manufacture of highly loaded bulky parts.

Known alloy based on titanium of the following chemical composition, wt.%:

aluminum 4.0-6.0 molybdenum 4,5-6,0 vanadium 4,5-6,0 chromium 2.0-3.6 iron 0.2-0.5 oxygen ≤0.2 nitrogen 0.05 titanium rest

(RF patent No. 2283889)

The airframe and engine designs, fastener parts are made from a known alloy.

The disadvantage of this alloy is the reduced level of fatigue strength of welded joints.

The closest analogue taken as a prototype is an alloy based on titanium of the following chemical composition, wt.%:

aluminum 4.3-6.0 molybdenum 4.0-5.6 vanadium 4.0-5.6 chromium 0.5-1.5 iron 0.5-1.5 zirconium 0.03-0.5 copper 0.003-0.15 nickel 0.003-0.15 oxygen 0.02-0.2 carbon 0.01-0.2 nitrogen 0.01-0.05 hydrogen 0.003-0.03 titanium rest

(RF patent No. 2082802)

The disadvantages of this alloy are not high enough low-cycle fatigue (MCU) of welded joints and low thermal stability of the base metal, which does not allow the use of this alloy for the manufacture of products such as engine mounts.

The disadvantages of products from the known alloy is not sufficiently high reliability and resource.

An object of the invention is to increase low-cycle fatigue (MCU) of welded joints and thermal stability of the base metal.

This object is achieved by the fact that the proposed alloy based on titanium containing aluminum, molybdenum, vanadium, chromium, iron, zirconium, copper, nickel, oxygen, carbon, nitrogen and hydrogen, which additionally contains hafnium in the following ratio, wt.%:

aluminum 4.3-6.0 molybdenum 4.0-5.6 vanadium 4.0-5.6 chromium 0.5-1.5 iron 0.5-1.5 zirconium 0.03-0.5 copper 0.003-0.15 nickel 0.003-0.15 oxygen 0.02-0.2 carbon 0.01-0.1 nitrogen 0.01-0.05 hydrogen 0.003-0.015 hafnium 0.03-0.5 titanium rest

Moreover, it is preferable that the total content of oxygen, carbon and nitrogen in the alloy should satisfy the condition 0.15% ≤ [(% O) +0.5 (% C) +1.7 (% N)] ≤0.24%.

The authors found that the additional introduction of hafnium into the alloy with the stated content and ratio of components increases low-cycle fatigue (MCU) of welded joints and thermal stability of the base metal.

Examples of specific implementation

To study the mechanical properties of the alloy, in a vacuum arc furnace, ingots with the chemical composition within the proposed alloy (1, 2, 3, Table 1) and the prototype alloy (4, Table 1) were melted by the double remelting method.

Smelted ingots were forged in a hydraulic press onto slabs. After mechanical processing of the plates, 20 mm thick blanks were made from them, which were then welded by electron beam welding. The welded workpieces were subjected to hardening heat treatment. The test results of the mechanical properties of the samples cut from the base metal and welded joints are shown in table 2.

From table 2 it is seen that with increasing thermal stability, the values of the MCU of welded joints increased by 1.3-1.5 times.

Thus, the use of the proposed alloy will increase the operational reliability and resource of large-sized power parts and welded units of aircraft.

Table 1 No. Chemical composition, wt.% 0.15% ≤ [(% O) +0.5 (% C) +1.7 (% N)] ≤0.24% Al Mo V Cr Fe Zr Cu Ni ABOUT FROM N N Hf Ti one 4.3 4.0 4.0 0.5 1,5 0,03 0.003 0.003 0.02 0.10 0.05 0.003 0,03 rest 0.16 2 5,0 4.8 4.8 1,0 1,0 0.25 0,075 0,075 0.10 0.05 0,025 0.009 0.25 " 0.17 3 6.0 5,6 5,6 1,5 0.5 0.5 0.15 0.15 0.20 0.01 0.01 0.015 0.5 " 0.22 four 6.0 5,6 5,6 1,5 1,5 0.5 0.15 0.15 0.20 0.01 0.02 0.015 0.5 " 0.23 5 6.0 5,6 5,6 1,5 1,5 0.5 0.15 0.15 0.20 0.20 0.05 0,03 - " 0.45

table 2 Alloy Mechanical properties at 20 ° С base metal welded joint the initial state after exposure
350 ° C - 1000 hours the initial state σ _in , MPa δ,% σ _in , MPa δ,% σ _in , MPa MCU,
σ _max ^net
MPa (N _p = 5 · 10 ⁴ c) one 1480 12.5 1390 12.5 1360 64 2 1500 10 1490 9.5 1390 62 3 1530 9 1520 9 1410 60 four 1540 9 1540 8.5 1430 60 5 1470 8.5 1440 5 1350 fifty

Claims (3)

1. A titanium-based alloy containing aluminum, molybdenum, vanadium, chromium, iron, zirconium, copper, nickel, oxygen, carbon, nitrogen, hydrogen, characterized in that it additionally contains hafnium in the following ratio of components, wt.%:
aluminum 4.3-6.0 molybdenum 4.0-5.6 vanadium 4.0-5.6 chromium 0.5-1.5 iron 0.5-1.5 zirconium 0.03-0.5 copper 0.003-0.15 nickel 0.003-0.15 oxygen 0.02-0.2 carbon 0.01-0.1 nitrogen 0.01-0.05 hydrogen 0.003-0.015 hafnium 0.03-0.5 titanium rest 2. The titanium-based alloy according to claim 1, characterized in that the total content of oxygen, carbon and nitrogen in the alloy satisfies the condition 0.15% ≤ [(% O) +0.5 (% C) +1.7 (% N)] ≤0.24%. 3. A titanium-based alloy product, characterized in that it is made of an alloy according to any one of claims 1 and 2.