Production of disc-shape forged pieces from alloy of aluminium with ortho-phase titanium

FIELD: metallurgy.

SUBSTANCE: ingot is subjected to swaging-drawing to octahedron with total reduction of 1.6-1.7. Final forming is performed at shaped hammers at 4-5 displacements over hammer surface and, then, in closed sizing die. Total reduction ay final forming makes 3-5.

EFFECT: precise forged pieces with homogeneous fine-gram structure, high specific strength and ductility.

2 cl, 2 tbl, 1 ex

 

The invention relates to the processing of metals and alloys by pressure, and in particular to methods of manufacture of forgings drives hot deformation ingots of alloys based on titanium aluminides (intermetallic titanium alloys), based on the orthorhombic phase of Ti2NbAl. The invention can be used in the aviation and energy industry for the production of blanks for disks of gas turbine engines (GTE) and gas turbine plants.

There are three main groups of alloys based on titanium aluminides, with different phase composition: γ-alloys (TiAl), α2-alloys (Ti3Al) and ortho-alloys (Ti2NbAl), which have a unique set of physical and mechanical properties (high strength, low density, high temperature strength, high anti-corrosive properties, high resistance to fatigue and creep).

However, the main obstacle to large-scale applications of intermetallic alloys based on α2- and γ-phase is their low ductility (elongation, contraction and impact strength at room temperature). At the same time orthorhombic alloys have a slightly higher density than the TiAl alloys and Ti3Al, but despite this have a high low-temperature characteristics and high-temperature specific so the barb and plasticity, can be considered as a very promising material for the manufacture of critical parts of aerospace engineering.

A method of obtaining forged semi-finished products of cast alloys of the Ti-Al, which includes the pre-deformation in a given interval of velocities and temperatures at several stages in three mutually perpendicular directions. The technical result of the invention is to improve the technological plasticity of the cast material by implementing a more favourable scheme of deformation, which resulted in the volume of forgings is formed of a homogeneous and fine-grained structure (patent RF №203417, MCP B21J 5/00, 21J 1/04). The disadvantage of this method is that the method is adapted to receive laboratory specimens of alloys based on γ-titanium aluminides and does not allow guaranteed to get a quality semi-responsible destination primarily because of the possible presence of casting porosity in the bulk of the semi-finished product. This method is not suitable for the production of semi-finished blanks disks in an industrial environment.

Closest to the proposed invention is a method of obtaining heat-resistant titanium alloys on the basis of ortho-phase, which includes obtaining an intermediate material by forging in α2+B2 or In the field and subsequent annealing at a temperature of B2 region, as a result, the material is formed lamellar (O+B2) structure, allowing to increase the ductility and plasticity (patent JP 2011-52239 A, 2011.3.17, MCP C22F 1/18, SS 14/00, C22F 1/00). The disadvantage of this method is that the proposed technologies are not available for operation on elimination of casting porosity before deformation, which reduces the strength characteristics of the product. Also the disadvantage of this method is low KIM forgings due to the lack of final deformation and use flat Boykov and calibration stamp. A significant drawback of this method are the low strength and ductility of semi-finished product at room temperature deformation due to poor processing of the original cast billets, making it impossible to use this method for the manufacture of critical parts of the assignment.

The problem to which the invention is directed, is getting in an industrial environment forgings drives increased accuracy with a homogeneous fine-grained structure, which ensure high performance low-temperature and high specific strength and flexibility through the use of high-temperature gas-static treatment (GED) with subsequent deformation.

To solve this problem a method is proposed manufacturer is forged from alloy aluminide titanium-based ortho-phase, which includes the following steps:

1. GED ingot at a pressure of 900-1300 ATM and a temperature higher than the temperature of polymorphic transformation (TPP) aged 2-6 p.m.

2. The deformation is carried out according to the scheme:

- draft-drawing on the octahedron along the original axis of the ingot and rolling at a temperature of {(TPP+100)÷(TPP+200)}°C with a total ukonom 1.6 to 1.7. Deformation includes draught of the ingot in the end to a height equal to the diameter, the installation is mounted ingot forming on the surface and feed on the square, and then, after alternate installation on ribs, drawing on the plate with a length equal to the original length of the ingot, and running;

- deformation of this scheme at temperatures {TPP÷(TPP+100)}°C with a total ukonom 1,5-1,6;

strain using the multiple precipitation by heating with deformation rate of 20-25% on each phase at temperatures {TPP÷(TPP-50)}°C with a total ukonom 3-5. When this precipitation is performed first on the relief strikers with 4-5 displacements in the plane of the heads, and then in the calibration stamp.

3. Heat treatment of forgings disks involves a two-step annealing at temperatures below the temperature of polymorphic transformation.

GED ingot eliminates mold porosity in the ingot, the absence of which is one of the most important conditions for increasing the strength'hara the characteristics of disks.

Deformation scheme draft-drawing on the plate at a temperature of {(TPP+100)÷(TPP+200)}°C with a total ukonom 1,6-1,7 facilitates the grinding of the primary cast of β-grains in the whole volume of the semi-finished product by eliminating areas hindered deformation in the corners of the "square". Further deformation in accordance with the scheme at a temperature of {TPP÷(TPP+100)}°C with a total ukonom 1,5-1,6 provides for the formation of regulated homogeneous fine-grained microstructure. The final deformation, providing multiple draft with a total ukonom 3-5 at temperatures {TPP÷(TPP-50)}°C initially on the relief strikers with 4-5 displacements in the plane of the heads, and then in the calibration stamp, provides the formation of fine-grained vnutrikabinnoe structure.

Two-stage heat treatment provides the optimum combination of mechanical properties in the disk forgings of alloy aluminide titanium-based ortho-phase.

The technical result - improved performance properties: low temperature and high specific strength and ductility due to the receipt of forgings increased accuracy with a homogeneous fine-grained structure.

The example implementation.

The ingot ⌀190×400 mm, made from an alloy based on ortho-phase aluminide titanium, chemical composition (patent No. 2375484 RF) p is eveden in table 1, was melted using a double vacuum arc remelting.

Table 1
The chemical composition of the alloy
The content of chemical elements, % of the mass.
TiNbAlTheSiFe
base43,9-45,009,00-11,000,02-0,300,04-0,200,15

Then the ingot (TPP=990°C) was subjected to deformation under the scheme:

At the first stage: GED in gotostate when the pressure 1210 ATM and a temperature of 1140°C with a holding time of 4 hours.

At the second stage:

- heating to a temperature of 1140°C and sediment to a height of 250 mm and a diameter of 250 mm with ukonom 1,4;

is heated to a temperature of 1140°C and drawn on a square with sides equal to 200 mm Spacing on the plate size 200 mm, height 400, with ukonom 1.6 and running on ⌀ 190 mm Total UCAV at a temperature of 1140°C was 2.2;

- heating to a temperature of 1080°C and sediment to a height of 300 mm and a diameter of 220 with ukonom 1,2;

is heated to a temperature of 1080°C and that the spacecraft into a square with side equal to 200 mm Spacing on the plate size 200 mm, height 400, with ukonom 1.4 and running on ⌀ 190 mm Total UCAV at a temperature of 1080°C was 1.7;

- sludge on the relief strikers with 4 moves along the plane of the striker, with the degree of deformation of 25% on the first 4 sub-stages and 20% in the last 2 sub-stages;

- heating to a temperature of 960°C and sediment to a height of 300 mm;

is heated to a temperature of 960°C and sediment to a height of 225 mm;

is heated to a temperature of 960°C and sediment to a height of 180 mm;

is heated to a temperature of 960°C and sediment to a height of 130 mm;

is heated to a temperature of 960°C and sediment to a height of 100 mm;

is heated to a temperature of 960°C and the precipitate in the calibration stamp to a height of 80 mm

Total UCAV at a temperature of 960°C amounted to 3.75.

Forged disk LPT ⌀ 500 mm from the ingot of alloy aluminide titanium-based ortho-phase obtained by the proposed method, was subjected to mechanical tests.

Were also tested billet alloy with the chemical composition presented in table 1, but made according to the technology described in the method prototype. Table 2 presents the mechanical properties of forgings intermetallic titanium-based alloy ortho-phase obtained by the proposed method and the method prototype.

Table 2
Mechanical properties
Manufacturing technologyNo. of experimentProperties at temperatures °C
20650
St/ρ, kmδ, %St/ρ, kmδ, %
The proposed method121-236-718-199-12
Prototype method214-163-48-97-8

Thus, the proposed method can improve the quality of forgings by improving the operational properties by the intensification of the study of the structure of the alloy and to produce blanks of high accuracy with a homogeneous fine-grained structure. The proposed method can improve at room temperature ductility in 2 times and specific strength 1.5-1.7 times, at the operating temperature - specific strength 2 times and plasticity in 1,3-1,5 times and, as a consequence, increase the life of the product is approximately 1.5 times.

1. A method of manufacturing a disk forgings hot deformation of ingots of the alloy-based aluminide titanium, based on the orthorhombic phase of Ti2NbAl, including multiple software deformation of the ingot to heat treatment at temperatures above and below the temperature of polymorphic transformation (TPP) and subsequent heat treatment, characterized in that the first deformation provide a scheme of sediment-feed on the octahedron with a total ukonom 1.6 to 1.7, and the final deformation with a total ukonom 3-5 provide relief strikers with 4-5 movements thereon ingot and then closed the calibration stamp.

2. The method according to claim 1, characterized in that the provision of deformation of the ingot is held high temperature gas-static treatment at a pressure of 900-1300 ATM and temperatures above TPP.



 

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