RU2686160C1 - Welding electrode - Google Patents

Abstract

FIELD: technological processes.SUBSTANCE: invention can be used for welding and repair of quality reinforced superalloys, which, in particular, are used for production of components of gas turbine. Electrode (10) comprises shell (14) formed from plastic material, outer coating (16), including flux material, and core (12), including at least one of flux material and alloying material. Outer coating is made in form of multiple discrete segments. Ends of segments are formed for interaction with adjacent ends so that possibility of electrode bending is provided. Outer coating comprises flexible cellulose binding material including fibrous cellulose. Fibers extend inward from the electrode surface to provide an electrical continuum between the outer surface and the core. Shell contains superalloy elements, and alloying material of the core complements the shell to produce the desired superalloy material at electrode melting.EFFECT: bendable electrode makes it possible to feed it from coil at continuous automatic welding.12 cl, 6 dwg

Description

Link to the related application

This application is a partial continuation of US patent application number 13/754983, filed January 31, 2013 (patent attorney number 2012R28299US), the contents of which are included in this application.

The technical field to which the invention relates.

The invention relates generally to the field of compounding metals and, in particular, to welding and repairing materials using a consumable electrode containing a flux.

The level of technology

Welding electrodes are usually formed by multi-stage drawing relative to plastic material from the rods. When the material hardens due to mechanical hardening (formation of dislocations) during each drawing stage, intermediate annealing is performed to eliminate such mechanical strengthening, reduce stress and improve ductility of the material for subsequent drawing stages. The material of superalloys, which are used for the manufacture of gas turbine engines, have extremely high strength and low ductility, even at very high temperatures. Due to these characteristics, annealing has a limited ability to improve the plasticity of the material of superalloys. As a result, it is difficult to form welding electrodes from the material of superalloys, in particular, high-quality hardened gamma alloys with a high content of aluminum and titanium, such as alloys 247, 738, 939, etc.

The concept of superalloy is used here, as is usual in the art, i.e. to indicate a highly resistant to corrosion and oxidation of the alloy, which has excellent mechanical strength and resistance to creep at high temperatures. Superalloys typically have a high nickel or cobalt content. Examples of superalloys include alloys sold under trademarks and brand names Hastelloy, Inconel alloys (i.e. IN 738, IN 792, IN 939), Rene alloys (for example, Rene N5, Rene 80, Rene 142), Haynes alloys, Mar M, CM 247, CM 247 LC, C263, 718, ECY 768, 282, X45, PWA 1483 and CMSX (for example, CMSX-4) single crystal alloys.

Arc welding of metals with a welding zone protection (SMAW) is a process of manual arc welding using a flux-coated consumable rod electrode. Electric current is used to form an electric arc between the electrode and the part, thereby melting the electrode and part of the part to form a welded joint. Due to the simplicity and versatility of the SMAW process, it is one of the most popular welding processes. The disadvantage of the SMAW process is the use of a rigid rod electrode, which usually excludes its use in continuous or automatic welding processes, in which a bendable electrode is usually supplied from a coil.

In arc welding using flux cored electrode wire (FCAW), a tubular alloy electrode containing flux is used. Since the flux can be in the form of a powder and is enclosed inside a tubular sheath made of an alloy, the electrode can be bent and it can be stored in the form of a roll, due to which continuous and automatic welding is possible.

Conventional welding electrodes are made of plastic material such as stainless steel. For example, in published US patent application US 2004/0173592 A1, an electrode is disclosed that includes a stainless steel shell surrounding a core containing an alloy material and a flux. Conventional electrodes are also designed for welding some materials of low strength superalloys. For example, in published US patent application US 2012/0223057 A1, a coated electrode is disclosed, which is used for welding tungsten electrode in an inert gas of certain superalloys. The electrode includes a solid core formed from a superalloy material and an outer coating of a flux material.

Brief Description of the Drawings

The invention is explained in the following description with reference to the accompanying drawings, which depict:

FIG. 1 - radial section of the electrode;

FIG. 2 - axial section of the electrode;

FIG. 3 is a radial section of the electrode along line 3-3 of FIG. 2;

FIG. 4 - radial section of the electrode;

FIG. 5 shows a cladding process using the electrode of FIG. 4 and arc torch using cold metal; and

FIG. 6 shows a cladding process using the electrode of FIG. 4 and the energy beam.

Detailed Description of the Invention

This invention is intended to develop improved technologies for applying and repairing high-quality hardened gamma superalloys, which are commonly used for gas turbine components along the hot gas path. The technology of laser powder deposition has been developed, which can be used for reliable deposition of even the highest strength superalloys. See, for example, the published application for US patent US 2013/0140279 A1, the full content of which is included in this description, in which are indicated (see Fig. 6 of this application) superalloys which are difficult to weld depending on the aluminum and titanium content, called here are high-quality hardened gamma superalloys. Applicants also recognize that conventional welding electrodes are not suitable for continuous automatic welding of these high-quality hardened gamma superalloys.

FIG. 1 shows a radial section of an electrode 10 comprising a sheath 14 surrounding a core 12. In addition, as shown in FIG. 1, the shell 14 has an outer cover 16. In various embodiments of the electrode 10, the core 12 and the outer cover 16 include various materials, as will be explained below. In each embodiment of the electrode 10, the shell 14 is formed from a plastic material, such as an extrudable set of elements with a composition of elements defining the desired superalloy material. In one exemplary embodiment, the plastic material is, for example, pure nickel or an alloy of nickel and chromium or an alloy of nickel, chromium and cobalt. Plastic materials are in this case materials having a minimum elongation of 10% and which are suitable for drawing into thin wire by cold extrusion with suitable intermediate annealing, usually stainless steel and wrought nickel-based alloys (as opposed to cast superalloys). In one exemplary embodiment, the core 12 includes a powder alloying material that includes elements that complement the elements in the plastic material to complete the composition of the elements that define the desired superalloy material. In one embodiment, the alloying material includes one or more of the elements Cr, Co, Mo, W, Al, Ti, Ta, C, B, Zr, and Hf. The flux can be incorporated into the outer coating 16 and / or into the core 12. The flux in the core 12 can be in the form of a powder, and the outer coating 16 can be applied as a continuous coating, or the powder can be held in a binder material. As will be understood by those skilled in the art, the flux material provides slag functions, and can create a coating gas when the electrode 10 is melted. In one embodiment, the flux material is not a metallic powder, such as, for example, alumina, fluorides and silicates.

In one embodiment of the electrode 10, the core 12 is formed of an alloying material, the shell 14 is made of plastic material, and the outer coating 16 is formed of a flux material.

In another embodiment of the electrode 10, the core 12 is formed of an alloying material, the shell 14 is made of a plastic material, and the outer coating 16 is formed of an alloying material and a flux material.

In another embodiment of the electrode 10, the core 12 is formed from an alloying material and a flux material, the shell 14 is made of a plastic material, and the outer coating 16 is formed from a flux material.

In another embodiment of the electrode 10, the core 12 is formed of a flux material, the shell 14 is made of a plastic material, and the outer coating 16 is formed of an alloying material and a flux material.

In another embodiment of the electrode 10, the core 12 is formed from an alloying material and a flux material, the shell 14 is made of a plastic material, and the outer coating 16 is formed from an alloying material and a flux material.

In another embodiment of the electrode 10, the core 12 is formed of a flux material, the shell 14 is made of plastic material, and the outer coating 16 is formed of an alloying material. In one exemplary embodiment, the alloying material is formed in the outer coating 16 using electrodeposition coating.

In another embodiment of the electrode 10, the core 12 is formed from a flux material and an alloying material, the shell 14 is made of a plastic material, and the outer coating 16 is formed from an alloying material.

In another embodiment of the electrode 10, the outer coating 16 is formed from a flux material enclosed in a flexible binder material, such as cellulose, so that the electrode 10 can be wound onto a drum. In one embodiment, a thin coating of cellulosic material, such as fiber and woven pulp, is used to provide flexibility for winding the electrode 10 onto the drum. The particles of the flux material and / or alloying material may be retained in the outer coating with a cellulosic material, or the fiber cellulosic material may be coated with a flux material and / or alloying material in the outer coating 16. In addition to increasing the flexibility of the electrode 10, the cellulosic material may contribute to shielding by generating one or more gases, such as, for example, carbon monoxide, carbon dioxide and hydrogen.

In another embodiment of the electrode 10, the core 12 contains any hygroscopic material used in the electrode, and the outer coating does not contain a hygroscopic material. Hygroscopic materials, such as finely powdered metal alloys, agglomerated fluxes and binders, such as water glass (Na ₂ (SiO ₃ )) and sodium silicates (Na ₂ (SiO ₂ ) _n O), are known as moisture absorbers in ambient air, which is a problem for the welding electrode due to the decomposition of water with the formation of hydrogen and oxygen at welding temperatures. Covered with flux electrodes, according to the prior art, are kept dry by storage at elevated temperatures before use. This invention can eliminate this problem by holding all hygroscopic materials with protection from the atmosphere by being inside the core 12. In one embodiment, only non-hygroscopic materials are provided in the outer coating 16. Non-hygroscopic materials include materials such as fused flux components or specially designed products reaction, as indicated in the patent US 4 662 952.

In those embodiments in which the outer coating 16 is formed from a flux material, the electrode 10 can be used in arc welding of metals with a welding zone protection (SMAW) of high-quality hardened gamma superalloys. However, the use of the above embodiments of the electrode 10 is not limited to SMAW, but may extend to any type of conventional arc welding, such as, for example, arc welding with a tungsten electrode in an inert gas (GTWA), arc welding of metals in shielding gas (GMAW), arc welding submerged arc (SAW) and arc welding with cored wire (FCAW).

FIG. 2 shows in axial section an electrode 10 '. FIG. 3 shows a cross section of the electrode 10 ′ along line 3-3 in FIG. 2. Electrode 10 ′ comprises a wire 14 ′ of plastic material, which is a solid core of plastic material. The wire 14 'of the electrode 10' is coated with an outer coating 16 ', which is segmented into a plurality of segments 18, 20 of a flux material. FIG. 2 shows a portion of the length of the electrode 10 ′ with two segments 18, 20 of a segmented outer cover 16 ′, so that it will be clear to those skilled in the art that the segmented outer cover 16 ′ may include two or more segments.

The segments 18, 20 of the outer cover 16 ′ may optionally have interacting arc surfaces at opposite ends, so that the convex surface 22 is adjacent and may come into contact with the concave surface 24 on the adjacent segment. The arc adjacent surfaces preferably simplify the winding of the electrode 10 'on the drum, since the arc adjacent surfaces allow the segments 18, 20 to rotate relative to each other while minimizing the gap between the segments 18, 20. The wire 14' is formed from a plastic material that can bend without cracking, and a segmented outer coating 16 'allows bending without cracking a relatively fragile coating, such as a coating of a flux material. Although FIG. 2 shows that the segments 18, 20 have adjacent convex and concave surfaces, the segmented outer coating is not limited to this arrangement. For example, the segments may be adjacent spherical segments (for example, balls), with both adjacent arc surfaces being convex. In another embodiment, adjacent segments include a single arc surface that is concave and a neighboring arc surface that is convex and pressed against the concave surface. In another exemplary embodiment, the segments may be, for example, adjacent cylindrical segments with adjacent surfaces that are parallel to each other or that include adjacent concave and convex surfaces that are pressed against each other. The segments allow the bending of a core of wire made of plastic material without damaging the relatively brittle coating material, but the segments are not limited to any particular form.

When the electrode 10 'is wound on the drum, one end of the electrode 10' may not have segments 18, 20, so that the power supply can be connected to this end of the wire 14 '. The power supply can be connected to the wire 14 'using a slip ring, so that the power supply should not rotate with the electrode 10' on the drum.

As further shown in FIG. 2-3, the electrode 10 ′ may include fibers 26 within the segmented outer cover 16 ′, which may extend, optionally, between segments 18, 20. The fibers 26 may serve to reinforce the outer cover 16 ′, and since the fibers 26 extend from segment 18 to segment 20, they connect segments 18, 20 to each other, while simultaneously providing flexibility to bend the electrode 10 'on the drum. In one exemplary embodiment, the plastic material of the wire 14 'is an extrudable set of elements defining the composition of the desired superalloy material, and the fibers 26 include metal elements that complement the plastic material to form the desired superalloy material when the electrode melts. The fibers 26 can form a metal screen surrounding the central wire 14 'by segments 18, 20 of flux material arranged along the length of the metal screen so that segments 18, 20 can be displaced relative to each other when the electrode is bent due to the flexibility of the screen between segments 18, 20 In other embodiments, the fibers 26 may be ceramic fibers, and the material of the ceramic fibers may provide the function of the flux. In one exemplary embodiment, as shown in FIG. 3, the fibers 26 may extend radially inside the outer cover 16 to come into contact with the wire core 14 'to ensure an electrical continuity between the fibers 26 and the wire 14'. This arrangement facilitates an electrical continuity between the power supply source (not shown) and the wire 14 'through the fibers 26, 26'. For example, the power supply may have electrical contact with the fibers 26 'through the electrode drive wheels (not shown), which are in contact with the outer surface of the electrode 10', and thus may be in electrical connection with the wire 14 '. An unbroken electric circuit eliminates the need to connect to the bare wire 14 'of the power supply at the end of the drum. Although FIG. 3 shows four metal fibers 26 'located in different radial positions between the fibers 26 and the wire 14', the embodiment is not limited to this arrangement and may include more or less than four metal fibers 26 'which may be located in other radial positions, instead of those shown in FIG. 3

Although FIG. 2 and 3, fibers 26 are shown inside the segmented outer cover 16 ′, in other embodiments, the segmented outer cover 16 ′ does not have reinforcing fibers, but has many segments 18, 20 of a flux material without reinforcing fibers. In addition, the reinforcement fibers may optionally be included in the outer cover 16 in FIG. 1. In another embodiment, the plastic material of the wire 14 'is an extruded set of elements defining the composition of the material of the desired superalloy, and the outer coating 16' contains an alloying material including elements that complement the plastic material to form the material of the desired superalloy when the electrode melts.

Although FIG. 2 and 3, it is shown that the wire 14 'comprises a solid core of plastic material, the electrode 10' may optionally have a sheath of plastic material with a hollow core, as shown in FIG. 1, while the alloying material is contained within the core 12.

FIG. 4 shows a cross section of a 10 электрод electrode having a shell 14 formed of a plastic material, such as an extrudable set of elements with a composition defining the material of the desired superalloy. In this embodiment of the electrode 10ʺ, the core 12 is formed from a flux material and an alloying material. In one embodiment, the alloying material is a powder metal material that includes elements that complement the elements in the plastic material to complete the composition of the elements that define the material of the desired superalloy.

FIG. 5 shows an embodiment in which a layer of high-quality deposited reinforced superalloy material 50 is deposited on a superalloy substrate 52 using an arc torch 54 using cold metal. The burner 54 is used to feed and melt the 10 элект electrode of FIG. 4, comprising a filling material 56 in the form of a wire core or a strip material comprising a hollow metal sheath 57 filled with a powder material 59 of the core. The core powder material 59 may include a alloying material, such as a powdered metal, and / or flux materials. Preferably, the metal shell 57 is formed from a material that can be given a hollow shape, such as nickel or nickel and chromium alloy or nickel, chromium and cobalt alloy, and the powder material 59 is selected so that the desired superalloy composition is formed when the filling material 56 melts. The shell contains enough nickel (or chromium or cobalt) to achieve the desired composition of the superalloy, so that, for example, the ratio of the solid phases of the shell compared to the core material powder, is 3: 2. The arc heat melts the filler material 56 and forms a layer of the desired superalloy material 50, covered with a slag layer 58. Flux powder material can be provided in the filler material 56 (for example, 25% of the core volume), or the electrode can be coated with a flux material, or any combination of these alternatives. Additional powdered metallic material may also be added to the melt by prior positioning on the surface of the substrate 52 or by direct feeding into the melt during the melting stage. In various embodiments, the flux may be electrically conductive (electroslag) or non-conductive (submerged arc), or it may be chemically neutral or additive. The filling material can be preheated to reduce the energy required for the process, in this case from an arc head using cold metal. The use of flux provides screening, thereby reducing or eliminating the need for an inert or partially inert gas, usually required in an arc process using a cold metal. Other processes that can be used using the above consumables and technologies include gas-electric metal welding, flux-cored wire welding, submerged arc welding (including using strip or wire), electroslag welding (including using strip or wire), plasma arc welding and welding with a tungsten electrode in an inert gas using wire.

FIG. 6 shows an embodiment in which a layer of high-quality hardened material 60 of a gamma superalloy is deposited on a superalloy substrate 62 using beam energy, such as a laser beam 64, to melt the 10 элект electrode of FIG. 4 including filler material 66. As mentioned above with respect to FIG. 5, the filler material 66 includes a metal sheath 68, which is made of a material that can simply be given a hollow shape, such as chromium or an alloy of nickel and chromium or nickel, chromium and cobalt, and the powder material 70 selected to form the desired superalloy composition when the filler material 66 is melted using a laser beam 64. The powder material 70 may include powdered flux as well as superalloy material. The heat of the laser beam 64 melts the filler material 66 and forms a layer of material 60 of the desired superalloy covered with a layer of slag 72. As mentioned above, the filler material can be preheated, for example, using an electric current, to reduce the energy required for the process. ray. In addition to this, it is also possible to use a hybrid process, including, for example, a combination of laser and arc welding.

One embodiment of the above electrode is designed for applying alloy material 247 as follows:

- the volume of the solid phase of the shell is about 60% of the total volume of the metal solid phase and is pure Ni;

- the volume of the core metal powder is about 40% of the total volume of the metallic solid phase, including a sufficient amount of Cr, Co, Mo, W, Al, Ti, Ta, C, B, Zr, and Hf, which melt and mix with pure nickel from the shell, with the formation of alloy 247 with a nominal percentage by weight of 8.3 Cr, 10 Co, 0.7 Mo, 10 W, 5.5 Al, 1 Ti, 3 Ta, 0.14 C, 0.015 V, 0.05 Zr and 1.5 Hf; and

- the volume of the powder flux of the core represents an additional, mostly non-metallic wire volume, approximately equal in magnitude to the volume of the metal powder, and includes various oxides, such as aluminum oxide, fluorides and silicates in a ratio of 35:30:35. The range of cell size of the flux ensures an even distribution inside the metal powder of the core.

Although FIG. 5 and 6 shows the welding technology using the 10 элект electrode of FIG. 4, this welding technology can be applied to any of the above mentioned embodiments of the electrode shown in FIG. 1-4. In addition, any conventional type of arc welding known to those skilled in the art can be applied using the electrodes of FIG. 1-4, including, for example, arc welding of metals with welding zone protection (SMAW).

For embodiments in which melting is provided by an arc, it is common to provide oxygen or carbon dioxide in a flux or protective gas in order to maintain the stability of the arc. However, oxygen or carbon dioxide reacts with titanium, and some titanium is lost in the form of steam or oxides during the melting process. According to this invention, the amount of titanium included in the filler material exceeds the amount of titanium desired in the composition of the applied superalloy to compensate for losses. For the alloy 247 given above as an example, the amount of titanium included in the core metal powder can be increased from about 1% to about 3%.

It is clear that other alloys can be applied, such as, for example, stainless steel, using a similar process in which the supplied core material is filled with a powdered core material, including powder flux and powdered metal. The powder metal can be used to increase the composition of the shell material, in order to obtain a facing material of the desired chemical composition. For embodiments in which there is a loss of material due to evaporation during the melting stage, the powder material may include an excess of the lost material to compensate for the loss. For example, when a stainless steel shell material in the form of an alloy 321 is applied under a protective gas containing oxygen or carbon dioxide, or when complete shielding is not provided with an inert protective gas, some titanium is lost due to reaction with oxygen or carbon dioxide or not completely shielded atmosphere. In such an embodiment, the core powder material may include powdered flux or powdered titanium or titanium alloy to compensate for the loss, which provides the desired facing composition of alloy 321.

Flux materials that can be used include commercially available fluxes, such as those sold under the names Lincolnweld P2007, Bohler Soudokay NiCrW-412, ESAB OK 10.16 or 10.90, Special Metals NT 100, Oerlikon OP76, Sandvik 50SW or SAS1, or fluxes which description shown in US Patent Application Publication No. US 2015/0027993 A1, the full content of which is included in this description. Flux particles can be ground to the desired cell size range before use. Flux materials known in the art typically include various oxides, such as alumina, fluorides, and silicates. In embodiments of the processes disclosed herein, preferably the metallic components of the desired facing material can be used, for example, chromium oxides, nickel oxides or titanium oxides. Any currently available iron, nickel or cobalt-based superalloys that are commonly used for high-temperature applications, such as gas turbine engines, can be connected, repaired or coated using the process according to the invention, including the above alloys.

Although various embodiments of the present invention have been presented and explained above, it is understood that these embodiments are given only as an example. Various variations, changes and substitutions are possible without departing from the scope of the present invention. Accordingly, this invention is limited only by the idea and scope of the appended claims.

Claims (26)

1. A welding electrode containing: - a shell formed of plastic material, - the outer coating containing the flux material located on the said shell, while the outer coating contains a plurality of discrete segments of the flux material, and the plurality of discrete segments contain non-parallel arc ends formed to interact with the corresponding ends of adjacent discrete segments to allow the electrode to be bent and - a core containing at least one of the flux material and the alloying material and located inside the shell, while the outer coating contains cellulosic binder material with adequate flexibility to allow the bending of the electrode on the coil, while the binder material contains fiber cellulose, wherein the fibers extend inward from the outermost surface of the electrode to provide an electrical, unbroken circuit between the outermost surface of the electrode and the core. 2. The electrode according to claim 1, wherein the outer coating further comprises an alloying material. 3. The electrode according to claim 1, wherein the core contains both the flux material and the alloying material. 4. The electrode according to claim 1, wherein the outer coating further comprises fibers. 5. The electrode according to claim 1, further comprising fibers interconnecting adjacent discrete segments. 6. The electrode according to claim 1, wherein the core contains a hygroscopic material, and the outer coating does not contain a hygroscopic material. 7. A welding electrode containing: - shell - the core containing the flux material and the alloying material and located inside the shell, wherein the shell contains an extruded set of elements of the desired superalloy material, and wherein the alloying material contains elements that complement the shell to form the desired superalloy material when the electrode is melted, - outer coating containing a plurality of discrete segments, while the segments contain non-parallel arc ends, formed to interact with the corresponding ends of adjacent segments to allow the electrode to be bent, while the outer coating contains cellulosic binder material with adequate flexibility to allow the electrode to be bent on the coil, and the binder material contains fiber cellulose, and while the fibers pass inward from the outermost surface of the electrode to provide an electrical unbroken circuit between the outermost surface of the electrode and the core. 8. The electrode according to claim 7, further comprising an outer coating comprising at least one of an alloying material and a flux material. 9. The electrode according to claim 7, further comprising fibers interconnecting adjacent discrete segments. 10. The electrode according to claim 7, in which the hygroscopic electrode material is located in the core. 11. A welding electrode comprising a core and a segmented outer coating located along the axial length of the core, wherein the segmented outer coating contains a plurality of segments with corresponding adjacent non-parallel arc end surfaces, wherein the segmented outer coating contains cellulosic binder material with adequate flexibility to allow the electrode to be bent on the coil, with the binder material containing fiber cellulose, and while the fibers pass inward from the outermost surface of the electrode to provide an electrical unbroken circuit between the outermost surface of the electrode and the core. 12. The electrode according to claim 11, further comprising an amplifying fiber connecting adjacent segments of a segmented outer coating with each other.

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