Titanium aluminide alloy and method for processing blanks thereof

FIELD: medicine.

SUBSTANCE: titanium aluminide alloy Ti3Al contains, wt %: Al 13-15, Nb 3-6, V 2-4, Zr 0.5-1.0, Mo 1-3, Sn 0.5-3, Si 0.1-0.3, Ti - the rest. A titanium aluminide alloy Ti3Al blank is subject to thermal hydrogen processing by hydrogen saturation followed by vacuum annealing. The hydrogen saturation of the blank is carried out to the concentration of 0.4-0.6 wt % at two stages, and then the blank is rolled. Vacuum annealing is two-staged at residual pressure no more than 5·10-5 mmHg.

EFFECT: heat-resistant titanium aluminide alloy Ti3Al is characterised by high plasticity and heat-resistance.

2 cl, 1 tbl

 

The invention relates to the field of non-ferrous metallurgy, namely the creation of an alloy on the basis of aluminide titanium Ti3Al having high ductility and heat resistance, and the method of processing workpieces from it. The invention can be used for the manufacture of parts of gas turbine engines, power plants and units, aviation, energy and marine use.

Famous-based alloy titanium Alloy titanium based and a product made of him" (patent RF №2210612), consisting of (wt.%): aluminum - 10-12, niobium - 38-42, molybdenum - 0,5-1,0, zirconium - 1-1,5, silicon - 0,1-0,25, vanadium - 1-1,5, carbon - 0,05-0,08, titanium - rest. However, this alloy because of its high content of niobium is not high enough values of specific strength at room temperature, and specific short-term and long-term strength for 100 hours at a temperature of 650°C.

The closest in composition of the alloy is the Alloy-based aluminide titanium" (patent RF №2081929), consisting of (wt.%): aluminum 13-15, niobium 3-4, vanadium 2-4, zirconium, 0.5 to 1.0, titanium - the rest is taken as a prototype. However, it has low ductility (elongation at tensile) at room temperature due to the small amount of β-phase (5-8%), and poor short-term and long-term strength at temperatures 650700°C.

The objective of the invention is in part alloy is developing based alloy aluminide titanium Ti3Al, which has a high ductility and heat resistance.

To solve this problem is proposed based alloy aluminide titanium Ti3Al containing: aluminum, niobium, vanadium, zirconium, and optionally contains molybdenum, tin, and silicon in the following ratio, wt.%:

Al - 13-15

Nb - 3-6

V - 2-4

Zr - 0,5-1,0

Mo - 1-3

Sn - 0,5-3

Si of 0.1-0.3

Ti - the rest.

Additional introduction of molybdenum in the alloy increases its ductility (elongation) at room temperature due to the increase in the structure of the number of β-phase to 10-12%. Additional introduction of tin and silicon increases the heat resistance of the alloy due to terrorstorm hardening α2-phase. In addition, tin lowers the degree of order, thus, at elevated temperatures in the deformation process involved and unordered microvolumes α-phase, which contributes to facilitating plastic deformation. The introduction of additional silicon also contributes to the formation of complex silicide (Ti, Zr, V)5Si3increasing long-term and short-term strength at 700°C. Additional introduction based alloy aluminide titanium, molybdenum, tin and silicon for the run ratio and a content of components increases the resistance of the alloy due to the formation of doped solid solution of titanium with Nb, Mo and Si, reducing coefficient oxygen diffusion at elevated temperatures.

A method of processing titanium alloys "Method of hydrogenation of titanium alloys" (patent RF №1780337). The method assumes that the saturation with hydrogen of the α - and α+β - titanium alloys. However, this method for alloys based aluminide titanium Ti3Al will not always achieve a given concentration of hydrogen due to its low solubility in the intermetallide.

The closest to the processing method is "a Method of obtaining products from titanium alloys and products obtained by this method (variants)" (patent RF №2338811), taken as a prototype. However, this method assumes that the saturation with hydrogen to a concentration of 0.5-0.9% in a single phase at temperatures of 700-850°C, which could result in uneven distribution over the cross section of the semifinished product and increase the duration of the process.

The objective of the invention is in part processing method based alloy aluminide titanium Ti3Al - is to increase its plasticity and reducing the deformation resistance during the pressure treatment by hydrogen saturation and uniform distribution over the cross section of the workpiece while reducing the time of hydrogenation and obtaining high values of ductility at a given strength at room temperature and kratkofil is Noah and long-term strength at elevated temperatures due to the receipt in the process of vacuum annealing bimodal structure.

The technical result of the group of inventions is the creation of new heat-resistant material based on titanium and its mode of processing for parts operating at elevated temperatures, with improved characteristics of plasticity and creep properties.

To solve the problem billet of alloy-based aluminide titanium Ti3Al put cernovodeanu processing by hydrogen saturation with subsequent annealing in vacuum. The saturation of the workpiece hydrogen lead to a concentration of 0.4-0.6 wt.%, moreover, the process is carried out in two stages: in the first stage, the workpiece is heated to a temperature of 950-1050°C, incubated for 0.5-1.5 hours, then cooled with the furnace to a temperature of 850-900°C, soak for 20-30 minutes, putting pure gaseous hydrogen under pressure 730-750 mm Hg and maintained to achieve the concentration of hydrogen in the procurement of 0.2-0.3 wt.% when the temperature drops to 700-750°C, after which the workpiece is maintained at the same temperature for 1-3 hours; in the second stage, the workpiece is heated to a temperature of 850-900°C, incubated for 20-30 minutes, to restore the pressure of the hydrogen gas to 730-750 mm Hg, can withstand before reaching the hydrogen concentration in the harvesting of 0.4-0.6 wt.% when the temperature drops to 700-750°C, after which the workpiece is maintained at the same temperature for 2-5 hours and cooled to room temperature the s with a speed of 0.02 to 2°C/s, then the workpiece is subjected to rolling at a temperature of 850-950°C and a two-step annealing in vacuum with a residual pressure of not more than 5·10-5mm Hg at the first stage is at a temperature of 450-600°C with a holding time of 1-4 hours; in the second stage by heating to a temperature of 750-950°C with a holding time of 2-8 hours and cooled to room temperature with a speed of 0.1-5°C/s

Heating to temperatures 950-1050°C, exposure for 0.5-1.5 hours and slow cooling to temperatures of 850-900°C provide flow in the procurement processes of homogenization, the alignment patterns in the cross section and the cast alloy in equilibrium.

Introduction to alloy half (of 0.2-0.3 wt.%) a given quantity of hydrogen and a gradual lowering of the temperature in the saturation process allow 1.5 times to reduce the time of hydrogenation.

Isothermal exposure at 700-750°C for 1-3 hours and re-heated to 850-900°C with exposure for 20-30 minutes to ensure uniform distribution of the injected hydrogen in the cross section of the workpiece.

The increase in the structure of the number of β-phase after the first stage of processing, the recovery pressure of the hydrogen gas to 730-750 mm Hg and a gradual decrease in temperature during the hydrogenation up to 700-750°C resulted in 2 times to reduce the total time of saturation. Isothermal exposure after completion of the process of absorption of water the ode at temperatures of 700-750°C for 2-5 hours provides uniform distribution over the cross section of the workpiece.

The first stage of vacuum annealing at temperatures of 450-600°C with a holding time of 1-4 hours course provides the initial stages of the decay of the hydrogen-containing β-phase and the emergence of dispersed α(α2)-phase.

The second stage vacuum annealing at temperatures 750-950°C allows you to remove the hydrogen to safe concentrations (0,002-0,008 wt.%) and to form a bimodal structure α2phase, allowing higher values of strength and ductility at room temperature and high temperature strength.

The example implementation.

The ingot of the alloy composition of Ti - 14Al - 4Nb - 3V - 0,7Zr - 2Mo - 2Sn - 0,2Si (wt.%) produced according to the production technology of titanium alloys, which includes the manufacture of blended materials consumable electrode and smelting ingots triple vacuum arc remelting. Machined castings were subjected to upsetting. Machined billet was subjected to saturation with hydrogen. For this purpose it was placed in a vacuum-hydrogen furnace, heated to a temperature of 1000°C, was kept for 1 hour and cooled in the oven to 875°C, kept for 25 minutes and was filled with hydrogen gas under a pressure of 740 mm Hg and maintained to achieve the concentration of hydrogen in the procurement of 0.25 wt.% by reducing the temperature to 725°C, after which the workpiece is kept at this temperature for 2 hours. Then the workpiece was heated up to those which the temperature of 875°C, stood for 25 minutes, restoring the pressure of the hydrogen gas to 740 mm Hg, stood before reaching the hydrogen concentration in the harvesting of 0.5 wt.% by reducing the temperature to 725°C, after which the workpiece is kept at the same temperature for 4 hours and cooled to room temperature with a speed of 0.05°C/s Then the workpiece was subjected to rolling at a temperature of 900°C 150-200°C lower than for this group of alloys without the use of reversible hydrogen alloying, with the aim of obtaining a sheet of semi-finished product with a thickness of 2 mm Sheet semi-finished products after removal of scale were subjected to a two-step annealing in vacuum with a residual pressure of not higher than 4.5·10-5mm Hg at the first stage is at a temperature of 500°C with a holding time of 3 hours; in the second stage by heating to a temperature of 800°C with a holding time of 7 hours and cooled to room temperature with a speed of 0.4°C/s properties of the samples cut from a sheet of semi-finished product of the claimed alloy, processed by the proposed method, are shown in table 1.

Table 1
Mechanical properties
σin20
The PA
σ0,220
MPa
δ20, %ψ20, %σin700
MPa
σ100700
MPa
132012104,05,0850400

Thus, the developed alloy based aluminide titanium Ti3Al and method of processing workpieces from it, it is possible to improve the ductility at lower temperature deformation due to reversible alloying components with hydrogen and uniform distribution over the cross section, to reduce the time of hydrogenation, to form billets structure providing increased values of ductility and heat resistance.

1. The alloy-based aluminide titanium Ti3Al containing aluminum, niobium, vanadium, zirconium, characterized in that it further comprises molybdenum, tin, and silicon in the following aspect] is the solution components wt.%:
Al - 13-15
Nb - 3-6
V - 2-4
Zr - 0,5-1,0
Mo - 1-3
Sn - 0,5-3
Si - 0,1-0,3
Ti - the rest.

2. The method of processing workpieces of alloy-based aluminide titanium Ti3Al according to claim 1, including cernovodeanu processing of the workpiece by hydrogen saturation of 0.4-0.6 wt.% and annealing in vacuum, and the saturation with hydrogen is carried out in two stages, with the first stage, the workpiece is heated to a temperature of 950-1050°C, incubated for 0.5-1.5 hours, then cooled with the furnace to a temperature of 850-900°C, soak for 20-30 minutes, putting gaseous hydrogen under pressure 730-750 mm Hg and maintained to achieve the concentration of hydrogen in the procurement of 0.2-0.3 wt.% when the temperature drops to 700-750°C, after which the workpiece is maintained at the same temperature for 1-3 hours, at the second stage, the workpiece is heated to a temperature of 850-900°C, incubated for 20-30 minutes, to restore the pressure of the hydrogen gas to 730-750 mm Hg, can withstand before reaching the hydrogen concentration in the harvesting of 0.4-0.6 wt.% when the temperature drops to 700-750°C, after which the workpiece is maintained at the same temperature for 2-5 hours and cooled to room temperature with a speed of 0.02 to 2°C/s, then the workpiece is subjected to rolling at a temperature of 850-950°C, and annealing in vacuum is carried out on two levels with a residual pressure of not more than 5·10-5mm Hg, and at the first stage the temperature is re 450-600°C with a holding time of 1-4 hours, and in the second stage by heating to a temperature of 750-950°C, aged 2-8 hours and cooled to room temperature with a speed of 0.1-5°C/S.



 

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