RU123355U1 - DEVICE FOR OBTAINING A SHOWER CASTING WITH A SINGLE CRYSTAL STRUCTURE - Google Patents

Abstract

A device for producing a casting of a blade with a monocrystalline structure of a given crystallographic orientation, having a feather and at least one shelf, containing a ceramic mold in which a seeding cavity with a single crystal seed placed in it is made in succession, a conical starting cavity, a mold cavity forming a casting made at an angle to the direction of crystallization of the casting, gating runs and the profitable part, characterized in that the starting cavity has a taper inclination angle relative to the direction of crystallization of the casting 30-45 °, is simultaneously connected to the edge of the lower shelf of the casting, with the trailing edge of the feather and with the edge of the upper shelf of the casting the mold cavity forming the casting and the gating runs are made at an angle of 35-85 ° to the direction of crystallization of the casting.

Description

The utility model relates to the field of foundry and can be used to produce single-crystal castings, for example, nozzle and working turbine blades of modern gas turbine engines (GTE) and gas turbine units (GTU) made of heat-resistant nickel alloys.

A device for producing single-crystal castings of turbine blades is known, in which the single-crystal structure is generated from a seed placed in a special ceramic mold pocket or from a seed in combination with a crystal sampler in the form of a spiral gate (patents EP No. 0127552, EP No. 0087379).

The disadvantage of this device is insufficient nutrition in thin sections, which does not allow the formation of a fully single-crystal blade, that is, one in which not only a feather, but also a lock with a shelf is single-crystal. When the structure of the blade itself is formed, extraneous grains form in the shelf zone, in particular along the edges of the castle shelf, which is a defect in structure.

A device is known for producing a casting with a single-crystal structure, mainly a turbine blade, consisting of a feather, a lock shelf, a lock and a profitable part, which contains a ceramic mold, at the base of which there is made a sequential seed cavity with a single-crystal seed placed in it with a given orientation, a conical starting cavity, connected by a crystal sampler with a mold cavity forming a casting of the blade, and a profitable part feeding the casting in the process of directional crystallization, which matured arranged in the direction of the axis of crystallization (US patent №4714101).

A disadvantage of the known device is the difficulty of forming a structure in the shelves of the blades, since the growth of a single crystal in the radial direction relative to the main temperature gradient is often accompanied by the appearance of foreign crystals that arise along the edges of the shelf, mainly from the input and output edges of the pen, which leads to marriage of castings and reduced casting yield.

The closest analogue taken as a prototype is a device for producing a casting with a single crystal structure having at least one shelf and a profitable part containing a ceramic form in which a seed cavity is arranged in series with a single crystal seed placed in it with a given crystallographic orientation, a conical starting cavity, a cavity molds forming the casting, the profitable part and the gateways connecting the starting cavity with the edges of at least one shelf of the casting, in which m the mold cavity and runner passages formed at an angle 10-45 ° to the axis and toward a lucrative part of the casting crystallization, thus starting the conical cavity is connected with the flange casting (RF Patent №2400326).

The disadvantage of the prototype device is the difficulty of forming a single crystal structure in the casting, due to the fact that the maximum angle of inclination of 45 degrees relative to the direction of growth is insufficient to prevent the formation of foreign crystals. This leads to a decrease in the yield of single-crystal castings in structure.

The technical task of the proposed utility model is to increase the yield of single-crystal castings by reducing the likelihood of the formation of foreign crystals on the shelves of the castings of the blades.

To solve this problem, a device is proposed for producing a casting of a blade with a single crystal structure of a given crystallographic orientation, having a pen and at least one shelf, containing a ceramic shape, in which a seed cavity with a single crystal seed placed in it, a conical starting cavity, a shape cavity forming casting, made at an angle to the direction of crystallization of the casting, the gateways and the profitable part characterized in that the starting cavity has a slope angle of the cone relative to the crystallization direction of the casting 30-45 °, is simultaneously connected with the edge of the lower shelf of the casting, with the outlet edge of the pen and with the edge of the upper shelf of the casting, and the mold cavity forming the casting and gate runs is made at an angle of 35-85 ° to direction of crystallization of the casting.

With this design of the mold, after filling it with metal, in the process of directed crystallization, the single-crystal structure, originating from the seed, grows into a starting cone, which is connected simultaneously with the edges of the lower shelf of the blade, the outlet edge of the feather blade and the edge of the upper shelf. In this case, the crystallization front does not have discontinuities during the formation of the blade structure, which means that the formation of subgrains with a large misorientation does not occur. This eliminates the possibility of the appearance of a subboundary with a large misorientation (Δα _[HKL] > 3 °) at the junction of the separated crystallization fronts (the first front is from the gate-crystallizer and the upper shelf, the second from the lower shelf and the feather of the blade) - called substructure of the 1st kind. The presence of such misorientation is unacceptable for castings made of heat-resistant nickel-free carbon alloy. The transverse subboundary can lead to a significant loss of material strength, which means that its presence is a defect in structure. In addition, hot cracking often occurs along this boundary in the directional crystallization process.

The starting cavity, which forms the starting cone, with an angle of inclination of the cone relative to the crystallization direction of 30-45 ° allows you to reliably bring the structure directly to several parts of the casting, regardless of the ratio of its length and height. It was established that an increase in the cone slope angle of more than 45 ° during crystallization leads to the formation of foreign crystals, a decrease in this angle less than 30 ° unreasonably increases the length of the starting cone and the duration of the directed crystallization process. The inclination of the cavity of the mold forming the casting from 35 ° to 85 ° allows you to form the structure of both the pen and the shelves of the blade using the angle of the shelf of the blade as a starting cone and crystal duct. In addition, the slope of the shelves relative to the direction of crystallization, eliminates micro-loosening on the surfaces of the shelves.

All this allows to increase the yield of suitable castings in the structure by reducing the likelihood of the formation of foreign crystals.

The invention is illustrated in the drawing. Figure 1 presents a General view of a device for casting a blade with a single crystal structure, where:

1 - Seed cavity with a seed

2 - Starting cavity

3 - Lower shelf

4 - Pen

5 - Top shelf

6 - Gateways

7 - Profitable part

The single-crystal structure, which originated from the seed located in the seed cavity 1, during directed crystallization, grows through the starting cavity 2, into the lower edges of the shelves 3 and 5 and the outlet edge of the feather of the blade 4 connected to it; further, the single crystal grows in shelves 3 and 5 and in feather 4, which is facilitated by the angle of inclination of the casting relative to the direction of crystallization, during which the upper, most distant from the seed, edges of the shelves are fed with metal through the gateways 6 connecting the upper edges of the shelves 3 and 5 and profitable part 7 to eliminate looseness. In addition, the attachment of the starting cone to the shelves and the outlet edge of the feather blade simultaneously leads to the absence of a discontinuity of the growth front in the directional crystallization process.

In the production conditions of FSUE VIAM, three types of turbine blades were obtained: two types of nozzle blades (wide chord and nozzle blades with developed shelves) and a working blade with a retaining and locking shelves. To obtain a given crystallographic orientation of the casting of the blade, seeds were used from an alloy of the Ni-W-C system with a crystallographic orientation [001], obtained by the method of oriented cutting.

Model blocks were assembled depending on the design of the blades, in particular on the size of the pen and the shelves of the blade.

Example 1

On the wax model of casting a wide-chord nozzle blade, having a feather and two shelves, we solder the wax model of the gate-feeding system: gate-gates - crystal guides, feeders, profit and starting cone having a cone inclination angle of 30 °.

The nozzle blade casting models thus assembled were installed on the wax model of the casting bowl, two blade casting models in the block at an angle of 85 °, so that the starting cone connected to the lower edges of the shelves and the outlet edge of the blade feather was located in the expected crystallization direction.

In the assembled model blocks, starting seed was installed on the starting cones.

Ceramic suspension was applied in layers to model blocks.

From the obtained ceramic shell wax model was melted according to the known technology.

Hollow ceramic molds were calcined in an oven to give strength.

The resulting ceramic molds had cavities according to FIG.

Seeds were installed in the finished molds to ensure casting of a blade with a single-crystal structure of a given crystallographic orientation.

The molds were interfered with the UVCN9 directed crystallization unit and filled with the heat-resistant nickel alloy ZhS-36.

After pouring the molds and conducting the etching operation, all castings were subjected to visual inspection for the presence or absence of foreign crystals, as well as X-ray inspection on a DRON-3 diffractometer to certify the crystallographic orientation of the casting.

Example 2

The wax model of the gate-feeding system was soldered to the wax model of the nozzle blade casting, which had a feather and two developed shelves: gate runways — crystal guides, feeders, profit, and a starting cone having a cone inclination angle of 35 °.

The nozzle blade casting models assembled in this way were installed on the wax model of the casting bowl with two blade casting models in the block at an angle of 60 °, so that the starting cone connected to the lower edges of the shelves and the outlet edge of the blade feather was located in the expected crystallization direction.

Next, the technological operations were repeated in accordance with Example 1.

Example 3

The wax model of the gate-feeding system is soldered to the wax model of the casting of the working blade with a feather, locking and retaining shelves: gate runners - crystal ducts, feeders, profit and starting cone having a 45 ° tilt angle.

Thus assembled models of nozzle blade castings were installed on the wax model of the casting bowl, two models of blade casting in the block at an angle of 35 °, so that the start cone connected to the lower edges of the shelves and the outlet edge of the blade feather was located in the expected crystallization direction.

Next, the technological operations were repeated in accordance with Example 1.

As shown by visual and x-ray control of the obtained castings, all castings assembled according to the above diagram had a single crystal structure [001] with an accuracy of 5-7 °. The yield of the structure of castings obtained using the proposed device was 100%.

At the same time, prototype turbine blade blocks were made. Some of the castings of the blades made according to the prototype had foreign crystals on the upper shelf of the blade, and between the shelf and the feather of the blade there was a large misorientation of subgrains. The yield on the structure of castings obtained using the prototype device was 75%.

Testing of the proposed device in industrial installations of directed crystallization such as UVNK showed that it ensures the production of structurally suitable single-crystal castings of blades with a completely single-crystal structure.

Thus, the use of the proposed device allows to obtain high-quality single-crystal blades, which increases the reliability and service life of modern gas turbine engines and gas turbine units.

Claims (1)

A device for producing a casting of a blade with a monocrystalline structure of a given crystallographic orientation, having a pen and at least one shelf, containing a ceramic mold, in which a seed cavity is arranged in series with a single crystal seed placed in it, a conical starting cavity, a mold cavity forming an angle cast to the direction of crystallization of the casting, the gateways and the profitable part, characterized in that the starting cavity has an angle of inclination of the cone relative to the direction crystallization of the casting is 30-45 °, it is simultaneously connected with the edge of the lower shelf of the casting, with the outlet edge of the pen and with the edge of the upper shelf of the casting, and the mold cavity forming the casting and the gate runs are made at an angle of 35-85 ° to the direction of crystallization of the casting.