RU2285736C1 - Method of production of articles from high-temperature nickel alloy - Google Patents

Abstract

FIELD: metallurgy; production of semi-finished products from high-temperature high-alloy wrought nickel-based alloys for manufacture of disks for gas-turbine engines working at temperatures higher than 600°C.

SUBSTANCE: proposed method includes preliminary deformation of blank by upsetting by two or more times, final deformation and heat treatment; first upsetting is performed in closed container; during next upsetting, technological metal ring at temperature of (0.02-0.5)T_def. is placed on blank heated to deformation temperature T_def. and free upsetting is performed in stamp tool heated to deformation temperature. Geometric parameters of ring are selected from given relationships. Preliminary deformation of blank is performed at intermediate annealing. Height-to-diameter ratio of starting blanks is no less than 3:1. Proposed method ensures forming of homogeneous fine-grain structure over entire volume of blank due to work in end zones.

EFFECT: simplified procedure; reduced labor consumption.

4 cl, 1 tbl, 5 ex

Description

The invention relates to the field of metallurgy, and in particular to the production of semi-finished products from heat-resistant high-alloy wrought nickel-based alloys, intended primarily for the manufacture of axisymmetric parts of gas turbine and rocket engines such as disks, hemispheres, shells, "glasses" and products of other shapes operating under extreme loads at operating temperatures above 600 ° C.

Upon receipt of disks made of heat-resistant nickel alloys, a vacuum-induction remelting ingot with subsequent vacuum-arc remelting is mainly used for deformation. In order to obtain a preform with uniform recrystallized grain and having the necessary plasticity as a result of preliminary deformation, the ingot is repeatedly deformed, reducing its transverse dimensions by pressing (extrusion) or by special forging techniques (for example, rotary forging). Then, repeated deformation is carried out by sediment in a closed container followed by free settlement on flat strikers in order to increase the diameter of the cross section.

A known method of manufacturing disks of highly alloyed heat-resistant nickel alloys, including preliminary deformation by pressing (extrusion) on a bar with a degree of deformation of 65-75% at a temperature below T.p. γ 'at 60-80 ° C, followed by prepressing in a closed container with a degree of deformation of 35-50% at a temperature below T.p. γ 'at 60-80 ° C; final deformation by combining precipitation and stamping at a temperature below T.p.r. γ 'at 40-60 ° C with a degree of deformation of 75-85%; heat treatment, consisting of preliminary annealing at a temperature below T.p. γ 'at 100-130 ° C; treatment for solid solution at a temperature in the range γ '± 10 ° С with regulated cooling and subsequent aging (ed. St. USSR No. 1637360).

The disadvantage of this method is the need for complex energy-intensive equipment, high labor intensity and the duration of reusable pre-pressing operations (precipitation in a closed container) to increase the cross section of the workpiece.

There is also a known method of producing blanks from low-alloy alloys using external metal short shells.

A short shell placed on the central zone of the workpiece increases the stability of the workpiece and reduces the unevenness of deformation during free draft due to the action of hydrostatic pressure and geometric factor. (L.N. Moguchy. Pressure treatment of hard-to-deform materials .- M .: Mashinostroenie, 1976, pp. 97-102) The known method of deformation with short shells during deformation of heat-resistant nickel alloys was not used, since it creates useful hydrostatic pressure the sheath material at a deformation temperature of 1050-1150 ° C should be more durable or equal to the workpiece material. Such materials are scarce and difficult to process, so the manufacture of shells from them is almost impossible.

A known method for producing stamped products, including heating the workpieces and deforming them in a heated stamp, in which the stamp is heated to a temperature higher than the temperature of the workpiece, and the workpiece is deformed at a variable speed.

In the process of deformation, the blanks of the workpiece, which are contactless and stamped, are heated due to heat transfer from a warmer tool to the workpiece. The method allows precipitation of workpieces with a large height to diameter ratio (H / D) compared to conventional or isothermal conditions and affect the intensity of the metal flow in the end zones of the workpiece (ed. St. USSR No. 485009).

The disadvantage of this method is that it is also impossible to apply for heat-resistant nickel alloys due to the increased deformation temperature. Technical difficulties and the problem of resistance of die material limit the possibilities of heating the dies at a temperature exceeding the deformation temperature of nickel alloys.

The closest analogue taken as a prototype is a method of producing a product from heat-resistant nickel alloy, which includes preliminary deformation of the workpiece by draft by two or more times in a closed container in isothermal conditions (prepressing) with a ratio of the height and diameter of the workpiece more than 2.5: 1; final deformation in the temperature range (T.p. γ'-80 ° С ÷ T.p. γ'-20 ° С) and heat treatment by preliminary annealing in the temperature range 900-1100 ° С, processing on solid a solution with regulated cooling and aging in the temperature range 650-1050 ° C (RF patent No. 2215059).

The disadvantage of the prototype method is the high complexity of obtaining products and the lack of uniformity of the structure in the resulting products.

The technical task of the invention is the creation of a method of producing a product from heat-resistant nickel alloy, which reduces the complexity of the process, as well as the formation of a homogeneous fine-grained structure throughout the volume of the workpiece due to the development of end zones.

To solve this problem, a method for producing a product from heat-resistant nickel alloy is proposed, including preliminary deformation of the workpiece by upsetting two or more times, final deformation and heat treatment, characterized in that during preliminary deformation of the workpiece, the first draft is carried out in a closed container, and with the next draft heated to a deformation temperature Tdef. the workpiece is installed technological metal ring having a temperature of (0.02-0.5) Tdef. and free sludge is carried out in a punch tool heated to a deformation temperature.

The geometric parameters of the technological metal ring are selected from the following ratios:

Нк = (0.25 - 0.75) Нз,

Дн.к = (1,2 - 1,7) Dз, where

Hk - the height of the ring,

Dp. - outer diameter of the ring,

Dz - the diameter of the cylindrical workpiece,

obtained after preliminary deformation,

Нз - height of the workpiece obtained

after preliminary deformation.

Preliminary deformation of the workpiece can be carried out with intermediate annealing, the need for which is determined by the state of the workpiece material.

The ratio of the height and diameter of the initial billet for preliminary deformation is chosen at least 3: 1.

According to the proposed method, the preliminary deformation of the workpiece is carried out by sediment in a closed container. Due to this, they provide longitudinal stability of the workpiece and the correct cylindrical shape after upsetting, and also achieve increased plasticity and uniformity of deformation during further free settlement of the workpiece by converting the cast large crystalline oriented structure to a more uniform recrystallized one. At the next deformation by free draft, heated to the deformation temperature Tdef. the workpiece immediately before being placed in the stamp set technological ring, pre-heated to a temperature of (0.02 - 0.5) Teff. As a result, heat exchange occurs between the workpiece and the process ring, and an uneven temperature field occurs over the volume of the workpiece. The central zone of the workpiece, which is in contact with the process ring, loses heat and hardens in comparison with more heated end zones, where the heat exchange does not have time to pass. As a result of this, with free upsetting in an instrument heated to a deformation temperature, the predominant metal flow and, accordingly, the development of the structure occur in the end zones of the workpiece. The method can significantly increase the stability of the workpiece with a free draft, i.e. its resistance to longitudinal bending, and use workpieces with a higher than in normal draft ratio of height to diameter (H / D). After free settlement with the process ring, the workpiece can take the form of a return barrel, and depending on the obtained H / D ratio, it is then upset in a closed container or freely upset in the usual way. In this case, the deformation is already predominantly in the central zone and the workpiece again takes a shape close to cylindrical. Subsequently, various axisymmetric parts are obtained from this blank by final stamping. The free draft operation with the technological ring according to the proposed method allows to replace part of the labor-intensive operations of precipitation in a closed container in the process of redistributing the workpiece with a larger diameter and thereby simplify and reduce the cost of the process.

The most suitable material for the process ring according to the proposed method is alloy steel, which does not form significant scale when heated.

The heating temperature and geometric parameters of the ring are selected depending on the geometry of the workpiece and the temperature and speed parameters of the deformation.

The need for intermediate annealing is determined by the state of the workpiece material. In some cases, the technical result of the claimed invention can be achieved without intermediate annealing. The need for intermediate annealing is determined by the grade of the alloy, its structural state and the magnitude of the deformation during pressure treatment. For example, the EP742 heat-resistant nickel-based alloy is less alloyed than the EK151 and EP975 alloys and is considered quite technologically advanced. In the pressed state, it allows a one-time deformation of up to 60% and, upon receipt of products of a simple form, allows to do without intermediate annealing.

Examples of implementation

For the practical implementation of the invention, heat-resistant nickel alloys for turbine disks EK151 and EP742ID were selected. In this case, we used ingots obtained by the traditional method of vacuum induction smelting followed by vacuum-arc remelting (VI + VD) and obtained using the directed crystallization method (VI + NC).

Preliminary and final deformation by sludge was carried out on a 630 ts press specialized for isothermal stamping with an induction heating installation of a punch tool.

Example 1. According to the proposed method, from a workpiece of alloy EP742 obtained from an ingot (VI + VD) with a diameter of 320 mm, followed by pressing with a degree of 65-70%, the product is obtained by performing the following operations:

1) turning the workpiece to a size of ⌀100 mm × 600 mm;

2) sediment in a closed container ⌀120 mm at a temperature of 1080 ° C (Tp.γ'-40 °) with a degree of deformation of 30% in a stamping tool, heated to Teff. = 1080 ° C;

3) free sludge with a process ring at a temperature of 1080 ° C (Tp.γ'-40 °) with a degree of deformation of 30% in a stamping tool heated to Teff. = 1100 ° C;

Technological ring parameters:

Tk = 23 ° C, Hk = 175 mm, Dn.k = 145 mm.

4) free sediment at a temperature of 1080 ° C (Tp.γ'-40 °) with a degree of deformation of 25% in a stamping tool, heated to Teff. = 1080 ° C;

5) the final deformation at a temperature of 1080 ° C (Tp.γ'-40 °) in a stamping tool, heated to Teff. = 1080 ° C;

6) quenching at a temperature of 1100 ° C for 8 hours;

7) aging at a temperature of 850 ° C for 6 hours;

8) aging at a temperature of 780 ° C for 16 hours.

Example 2. According to the proposed method, from a workpiece obtained from an ingot (VI + VD) with a diameter of 320 mm, followed by pressing with a degree of 65-70%:

1) turning the workpiece to a size of ⌀100 mm × 500 mm;

2) sediment in a closed container ⌀120 mm at a temperature of 1100 ° С (Т.р.γ'-40 °) with a degree of deformation of 30% in a stamping tool heated to Teff. = 1100 ° С;

3) annealing at a temperature of 1090 ° C (Tp.γ'-50 °);

4) free sludge with a process ring at a temperature of 1100 ° С (Тр.р. γ'-40 °) with a degree of deformation of 25% in a stamping tool heated to Teff. = 1100 ° С;

Technological ring parameters:

Tk = 23 ° C, Hk = 112 mm, Dn.k = 144 mm.

5) free sediment at a temperature of 1100 ° C (Tp.γ'-40 °) with a degree of deformation of 25% in a stamping tool, heated to Teff. = 1100 ° C;

6) annealing at a temperature of 1100 ° C (Tp.γ'-40 °);

7) the final deformation at a temperature of 1100 ° C (Tp.γ'-40 °) in a stamping tool, heated to Teff. = 1100 ° C;

8) annealing at a temperature of 1100 ° C (Tp.γ'-40 °);

9) heat treatment for solid solution at a temperature of 1155 ° C (Tp.γ '+ 15 °);

10) aging of 870 ° C for 6 hours + 760 ° C for 32 hours.

Example 3. According to the proposed method from an ingot (VI + NK) with a diameter of 105 mm, obtained by directional crystallization in ceramic form of constant cross section with a temperature gradient at the solidification front of 20-200 ° C:

1) turning the ingot to a size of ⌀100 mm × 450 mm;

2) sediment in a closed container ⌀120 mm at a temperature of 1150 ° C (Tn.p.γ '+ 10 °) with a degree of deformation of 25% in a stamping tool, heated to Teff. = 1150 ° C;

3) annealing at a temperature of 1150 ° C (Tp.γ '+ 10 °);

4) free sludge with a process ring at a temperature of 1090 ° C (Tp.γ'-50 °) with a degree of deformation of 25% in a stamping tool heated to Teff. = 1090 ° C;

Technological ring parameters:

Тк = 285 ° С, Нк = 188 mm, Dн.к = 170 mm.

5) free sediment at a temperature of 1100 ° C (Tp.γ'-40 °) with a degree of deformation of 25% in a stamping tool, heated to Teff. = 1100 ° C;

7) annealing at a temperature of 1100 ° С (Tp.γ'-40 °);

8) the final deformation in at a temperature of 1100 ° C (Tp.γ'-40 °) in a stamping tool, heated to Teff. = 1100 ° C;

12) annealing at a temperature of 1100 ° C (Tp.γ'-40 °);

13) heat treatment for solid solution at a temperature of 1155 ° C (Tp.γ '+ 15 °);

14) aging of 870 ° C for 6 hours + 760 ° C for 32 hours.

Example 4. According to the proposed method (condition of the initial billet according to example 3):

1) turning the ingot to a size of ⌀100 mm × 300 mm;

2) sediment in a closed container ⌀120 mm at a temperature of 1150 ° С (Tn.p.γ '+ 10 °) with a degree of deformation of 20% in a stamping tool heated to Teff. = 1150 ° С;

3) annealing at a temperature of 1150 ° C (Tp.γ '+ 10 °);

4) free sludge with a process ring at a temperature of 1090 ° C (Tp.γ'-50 °) with a degree of deformation of 25% in a stamping tool heated to Teff. = 1090 ° C;

Technological ring parameters:

Тк = 545 ° С, Нк = 225 mm, Dн.к = 204 mm.

5) the final deformation at at a temperature of 1100 ° C (Tp.γ'-40 °) in a stamping tool, heated to Teff. = 1100 ° C;

6) annealing at a temperature of 1100 ° C (Tp.γ'-40 °);

7) heat treatment for solid solution at a temperature of 1155 ° C (Tp.γ '+ 15 °);

8) Aging 870 ° C 6 hours + 760 ° C 32 hours.

Example 5. According to the prototype method of the ingot (VI + NK) (state of the original billet according to example 3):

1) turning the ingot to a size of ⌀100 mm × 400 mm;

2) sediment in a closed container ⌀120 mm at a temperature of 1150 ° С (Тр.р. γ '+ 10 °) with a degree of deformation of 25% in a stamping tool heated to Teff. = 1150 ° С;

3) annealing at a temperature of 1150 ° C (Tp.γ '+ 10 °);

4) sediment in a closed container ⌀135 mm at a temperature of 1050 ° C (Tp.γ '+ 10 °) with a degree of deformation of 25%;

5) annealing at a temperature of 1090 ° C (Tp.γ'-50 °);

6) free sediment at a temperature of 1100 ° C (Tp.γ'-40 °) with a degree of deformation of 25% in a heated stamping tool (in isothermal conditions);

7) annealing at a temperature of 1100 ° С (Tp.γ'-40 °);

8) the final deformation in the stamp at a temperature of 1100 ° C (Tp.γ'-40 °) in a stamping tool, heated to Teff. = 1100 ° C;

9) annealing at a temperature of 1100 ° C (Tp.γ'-40 °);

10) heat treatment for solid solution at a temperature of 1155 ° C (Tp.γ '+ 15 °);

11) aging of 870 ° C for 6 hours + 760 ° C for 32 hours.

The table shows that the proposed method can be implemented both on ingots obtained by the traditional method (VI + VD), and on ingots (VI + NK). Upon receipt of the parts according to the proposed method, replacing the operation of upsetting in a closed container with an operation of free upsetting with a process ring can reduce the cost of die tooling by 30%. In addition, due to the simplification of the process, the complexity of manufacturing the part is reduced by 10%. The proposed method also allows a greater degree to work out (grind) the structure in the end zones of the workpiece. This ensures uniformity of structure during further final stamping and heat treatment, and, ultimately, the stability of the properties of the product.

No. approx
yer The method of smelting and remelting H / D ref.
behind Parameters of the used technological ring End grain size
blanks, microns The complexity of the process
receive disk n / h Stamp cost
snap, rub. Temperature ° C Height, Nk., Mm Outer diameter, DNp.k., mm one 2 3 four 5 6 7 8 9 one Of the proposal
pulled VI + VD 6: 1 23 175 145 75 1620 1250000 2 VI + VD 5: 1 23 112 144 75 1620 1250000 3 way VI + NK 4,5: 1 285 188 170 85 1620 1250000 VI + NK 3: 1 545 225 204 90 1620 1250000 four Prototype method VI + NK 4: 1 Technological ring not applicable 110 1800 1750000

Claims (4)

1. A method of obtaining a product from a heat-resistant nickel alloy, comprising pre-deformation of the preform by upsetting two or more times, final deformation and heat treatment, characterized in that during pre-deformation of the preform, the first draft is carried out in a closed container, and during the next draft up to heated to deformation temperature Tdef. the workpiece is installed technological metal ring having a temperature of (0.02-0.5) Teff., and carry out free settlement in a stamping tool, heated to a deformation temperature. 2. The method according to claim 1, characterized in that the geometric parameters of the technological metal ring is selected from the following ratios: Нк = (0.25-0.75) Нз, Dn.k = (1.2-1.7) Dz, where Hk is the height of the ring, Дн.к - outer diameter of the ring, Dz - the diameter of the cylindrical billet obtained after preliminary deformation, Нз - height of the workpiece obtained after preliminary deformation. 3. The method according to claim 1, characterized in that the preliminary deformation of the workpiece is carried out with intermediate annealing. 4. The method according to claim 1, characterized in that the ratio of the height and diameter of the initial billet under preliminary deformation is at least 3: 1.