RU2560483C1 - Nickel-based solder to manufacture structure of blisk type - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: nickel-based solder contains the following on wt %: chrome 8.0-15.0; boron 2.0-3.5; aluminium 3.0-5.0; niobium 3.0-5.0; cobalt 12.0-17.5; titanium 1.5-3.7; nickel - the rest. The solder can be used to solder deformed and intermetallic nickel heat-resistant alloys with soldering temperature 1220°C maximum.

EFFECT: strength of soldered joints is ensured at level 0,8 of strength of the connected materials.

2 cl, 2 tbl, 3 ex

Description

The invention relates to the field of engineering, namely to nickel-based solders, which can be used in the manufacture of soldered parts of the hot path of turbines of gas turbine engines (GTE).

In the production of gas turbine engines, a mechanical locking connection is used to connect the blades to the disk. However, in the process of work on this mechanical connection is affected by significant static and dynamic loads. As a result, to ensure the required level of reliability of the mechanical locking connection, the disk-blade section of the blade in the cross section and, accordingly, of the disk exceeds the cross section of the working part of the blade blade by several times. This leads to a decrease in the material utilization factor (CMM), an increase in the complexity of manufacturing, and a significant increase in the mass of the product as a whole. The use of inseparable high-strength soldered disk-vane joints will reduce the laboriousness of manufacturing a Blisk type structure and reduce the weight of the product by up to 30% ["Features of diffusion brazing technology of heat-resistant alloy EP975 and casting single-crystal intermetallic alloy VKNA-4U as applied to Blisk design, Welding production 2013, No. 7, pp. 19-25.]. However, to obtain a “blisk” type construction, it is necessary to develop a solder that provides high strength of soldered joints of unlike alloys.

Known solder based on Nickel (see the publication of international application WO 96/37335, publ. 08/27/2004), having the following chemical composition in wt.%:

Chromium 9.5-16.6 Iron 0-5,4 Boron 1.24-1.47 Silicon 5.6-8.3 Molybdenum 0-8.9 Nickel rest

The disadvantages of this solder are the low level of heat resistance of the joints of disk heat-resistant nickel alloys with heat-resistant intermetallic nickel-aluminum alloys at temperatures up to 850 ° C and increased erosion activity of the intermetallic nickel-aluminum alloy.

From the prior art (RF patent No. 2283742, publ. September 20, 2006), nickel-based solder for brazing heat-resistant intermetallic nickel aluminum alloys of the following composition in wt.% Is known:

Chromium 25.0-32.0 Iron 0.06-0.5 Silicon 0.05-0.3 Tungsten 1.0-2.5 Molybdenum 0.05-0.6 Aluminum 7.5-9.0 Cobalt 0.1-1.0 Titanium 0.6-1.5 Nickel rest

This solder provides high heat resistance values for these alloys, but has a soldering temperature of about 1280 ° C. The soldering temperature of disk heat-resistant nickel alloys cannot exceed 1220 ° C due to the growth of grains of the deformable alloy and therefore cannot be used for soldering the above unlike combinations.

The closest analogue taken as a prototype (RF patent No. 2334606, publ. 09/27/2008), is the solder of the following composition, wt.%:

Chromium 7.0-9.5 Iron 0.4-1.7 Boron 2,3-3,3 Silicon 0.3-0.7 Tungsten 8.0-11.5 Carbon 0.05-0.15 Aluminum 1.1-2.8 Molybdenum 1.1-2.5 Niobium 0.8-2.5 Cobalt 8.0-11.0 Nickel rest

The disadvantage of the solder known from the prototype is the low level of heat resistance of the joints of disk heat-resistant nickel alloys with heat-resistant intermetallic nickel aluminum alloys at temperatures up to 850 ° C. In addition, the disadvantages are the impossibility of increasing the heat resistance of compounds by diffusion soldering with an increase in the holding time during soldering due to the formation of refractory compounds, mainly tungsten and molybdenum silicides in the middle of the brazed joint, and the excessive penetration of solder components along the grain boundaries of heat-resistant disk nickel alloys.

The technical task of the invention was to increase the heat resistance of the joints of disk heat-resistant nickel alloys with heat-resistant intermetallic nickel-aluminum alloys at temperatures up to 850 ° C, including the possibility of diffusion brazing. In addition, the temperature of brazing with this solder should not exceed 1220 ° C.

The technical result of the present invention is the development of a solder composition for brazing deformable and intermetallic nickel heat-resistant alloys in an unlike combination with a brazing temperature of not higher than 1220 ° C, ensuring the strength of soldered joints at a level of 0.8 of the strength of the materials being joined.

The technical result achieved is achieved by the fact that a nickel-based solder containing chromium, boron, aluminum, niobium, cobalt is proposed, characterized in that it additionally contains titanium in the following ratio of components in wt.%:

Chromium 8.0-15.0 Boron 2.0-3.5 Aluminum 3.0-5.0 Niobium 3.0-5.0 Cobalt 12.0-17.5 Titanium 1,5-3,7 Nickel rest

Preferably, the total content of aluminum and titanium is 4.5-8.7 wt.%.

The introduction of an additional component in the titanium alloy in the stated ratio with other components provides high heat resistance of the joints of disk heat-resistant nickel alloys with heat-resistant intermetallic nickel-aluminum alloys at temperatures up to 850 ° C. An increase in heat resistance is also facilitated by an increase in the total content of aluminum and titanium (4.5–8.7% by weight), and an increased content of cobalt reduces the tendency of solder to brittle fracture. The exclusion of molybdenum and tungsten from the composition of the solder ensured a decrease in the soldering temperature to 1220 ° C. The exclusion of silicon from the composition of the solder made it possible to exclude difficultly absorbable silicide eutectic components from the structure of the soldered seam, which increased the strength of soldered joints during diffusion curing of the solder.

Examples of implementation.

Smelting of the proposed solder, as well as the solder known from the prototype, was carried out in an argon flow at the LP32-67M installation. The mass of the obtained solder ingots was 80 g each. After smelting, the ingots were turned on a lathe to remove the casting peel. For ease of use, the solder ingots were ground to a particle size of not more than 400 microns using a planetary mill. After grinding, the solder powders were subjected to magnetic separation to remove solder particles contaminated with iron from grinding bodies. Table 1 presents the compositions of the proposed solders (examples 1-3) and solder, known from the prototype.

Soldering was carried out by heating in a vacuum oven at a temperature of 1200 ° C. The vacuum during the exposure was at least 5 · 10 ^-4 mm Hg. A portion of each solder in the form of pieces was fixed near the gap. The soldering time was 180 minutes.

The heat resistance of butt brazed joints was determined on samples of unlike compounds from EP975 and VKNA-25 alloys. Cylindrical samples of each alloy with a diameter of 16 mm and a height of 36 mm were soldered by the end surfaces in such a way that the seam on the soldered sample was in the middle part of the sample, located perpendicular to the axis of the sample. In each soldered specimen, the seam was the boundary between two alloys. Test samples were machined from a brazed cylindrical billet with a diameter of 16 mm and a length of 72 mm. The diameter of the working part of the sample was 5 mm from samples of two alloys.

The properties of the proposed solder and made by this solder compounds in comparison with the properties of the prototype are presented in table 2.

The operating temperature of the EP975 disk alloy should not exceed 850 ° C; therefore, this temperature was chosen for testing compounds from unlike alloys. K _{ass ps} is the attenuation coefficient of the brazed butt joint, equal to the ratio of the strength of the brazed joint to the strength of the base material, in this case, the strength of the EP975 alloy.

According to table 2, it is seen that the proposed solder provides the heat resistance of butt brazed unlike compounds from EP975 and VKNA-25 alloys more than that of the alloy known from the prototype. The strength of the butt joints made by the proposed solder is about 4 times higher than that of the joints made by the solder known from the prototype.

The use of the proposed solder when soldering parts of the hot gas turbine engine path will significantly increase the reliability of soldered joints of such promising structures as “blisk” (the blades are connected to the disk using one-piece joints) and provide a significant economic effect from increasing the gas turbine engine resource.

Claims (2)

1. Solder based on Nickel, containing chromium, boron, aluminum, niobium and cobalt, characterized in that it additionally contains titanium in the following ratio of components in wt. %:
Chromium 8.0-15.0 Boron 2.0-3.5 Aluminum 3.0-5.0 Niobium 3.0-5.0 Cobalt 12.0-17.5 Titanium 1,5-3,7 Nickel rest 2. Nickel-based solder according to claim 1, characterized in that the total content of aluminum and titanium is 4.5-8.7 wt.%.