BACKGROUND [0001] The present disclosure relates generally to the field of welding, and more particularly, to forming unique weld filler materials for welding.

[0002] Of all the high-temperature materials, nickel-based superalloys have the most favourable combination of mechanical properties, resistance to corrosion and processability for gas turbine construction for aircraft and power plants. This is due in part to the fact that nickel-based superalloys can be strengthened by precipitation of a g' phase. Nevertheless, cracks may still occur over time in nickel-based superalloy components that operate in a harsh environment, such as a gas turbine engine. As the manufacture of these components is complex and costly, efforts are made to repair damaged sections of the components instead of scrapping them all together. Thus, welding nickel-based superalloy components for their refurbishment is a desirable and cost-effective option.

[0003] However, welding of nickel-based superalloy materials has been known to be difficult. In order to circumvent the difficult weldability of g'-hardened nickel-based superalloys, welding is often performed with ductile welding fillers. Commonly used ductile weld fillers, such as IN-625, IN-617, Hast-W, and HA-282, were developed when gas turbine temperatures were relatively cooler than current and future designs. These ductile weld fillers, when used on current gas turbine components that operate at increasingly higher operating temperatures than those in the recent past, may not be able to withstand the oxidation that occurs at higher operating temperatures. [0004] For this reason, there is a need for ductile weld fillers that can withstand higher temperatures than those used in the past.

[0005] To determine the best weld filler metal for these applications, it is often desirable to test various chemistries of weld filler materials. However, testing of materials that are not commonly manufactured as weld filler metal is difficult. SUMMARY

[0006] In one construction, a method of forming alloy welding consumables for use in welding a base material includes providing a plurality of first welding consumables having a first diameter and a first chemical composition that closely matches the base material to be welded and providing a plurality of second welding consumables having the first diameter and a second chemical composition that is an alloy that is different from that of the base material. The method further includes winding a first quantity of the first welding consumables and a second quantity of the second welding consumables into a wound consumable having a chemical composition when welded that is a mixture of the base material and the alloy having a ratio equal to the ratio of the first quantity to the second quantity.

[0007] In another construction, a method of forming alloy welding consumables for use in welding a base material includes providing a plurality of first welding consumables having a first diameter and a first chemical composition and providing a plurality of second welding consumables having a second diameter that is two times the first diameter and a second chemical composition that is different than the first chemical composition. The method further includes winding a first quantity of the first welding consumables and a second quantity of the second welding consumables into a wound consumable having a chemical composition when welded that is a mixture of the first chemical composition and the second chemical composition having a ratio equal to the ratio of the first quantity to four times the second quantity.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a chart illustrating the relative weldability of various superalloys,

[0009] Fig. 2 is a chart of the coefficient of thermal expansion of various weld fillers and superalloy base materials, and

[0010] Fig. 3 illustrates a perspective view of a rotor blade or guide vane. [0011] Fig. 4 is a perspective view of a GTAW process.

[0012] Fig. 5 is a perspective view of two GTAW consumables wound together.

[0013] Fig. 6 is a perspective view of three GTAW consumables wound together Fig. 5 is a perspective view of two GTAW consumables wound together. [0014] Fig. 7 is a perspective view of an arrangement suitable for use in winding

GTAW consumables.

DETAILED DESCRIPTION

[0015] To facilitate an understanding of embodiments, principles, and features of the present disclosure, they are explained hereinafter with reference to implementation in illustrative embodiments. Embodiments of the present disclosure, however, are not limited to use in the described systems or methods.

[0016] The components and materials described hereinafter as making up the various embodiments are intended to be illustrative and not restrictive. Many suitable components and materials that would perform the same or a similar function as the materials described herein are intended to be embraced within the scope of embodiments of the present disclosure.

[0017] Fig. 4 illustrates the tools required for a welding process commonly referred to as Gas Tungsten Arc Welding (GTAW), which is also commonly known as Tungsten Inert Gas (TIG) welding. A TIG welding arrangement includes a torch 510 that includes a gas cup 515 or nozzle and a tungsten electrode 520 positioned partially within the cup 515 A consumable 525 in the form of solid weld wire is used to add material during the welding process. When TIG welding, a welder forms an electrical arc that extends from the tip of the tungsten electrode 520 to a base material 530 in the location where the weld is being made. The arc quickly heats and melts the base material 530 to form a weld pool 535 of molten metal. The welder manually feeds the consumable wire 525 into the weld pool 535 where the wire 525 melts and forms part of the weld bead after the molten metal cools. An inert gas 540 (e.g., argon) is discharged into the cup 515 and maintained around the arc and the weld pool 535 to protect the weld pool 535 from oxidation which can cause flaws in the weld. TIG welding is well-known for the quality of welds that can be formed using the process and is well-suited to delicate work or welding of materials that have lower weldability.

[0018] The addition of the consumable 525 to the weld pool 535 results in the weld bead being an alloy or mixture of the base material 530 and the consumable 525. In ideal situations, the chemical make-up of the consumable 525 is the same as that of the base material 530 and the weld bead is therefore chemically the same as the base material 530. However, when welding less weldable materials, it is often necessary to select a consumable 535 that is more easily weldable but that is chemically different than the base material 530. For example, Alloy-247LC is used as a base material 530 in some high temperature applications such as turbine blades. If those components require a weld repair, a chemically similar consumable material (i.e., Alloy-247LC) would be very difficult if not impossible to successfully weld. Rather, a more weldable material such as IN-617 would be used. However, IN-617 may not be a suitable material for the operating conditions of the component being repaired which can make it unsuitable for the repair.

[0019] Developing and testing alternative welding consumables can be difficult and expensive as a limited number of consumable chemistries are available. One way of forming and testing different consumable chemistries is to twist or wind available consumables into a wound consumable 545 as illustrated in Fig. 5. The wound consumable 545 illustrated in Fig. 5 includes two equally sized consumables with one being IN-617 (consumable 550) and the other being Alloy-247LC (consumable 555). When this wound consumable 545 is used to weld, the resulting weld bead will have a chemistry that is about 50 percent IN-617 and about 50 percent Alloy-247LC. This material is referred to herein as Ductilloy. As illustrated in Fig. 1, Ductilloy falls between IN-617 and Alloy-247LC and is therefore more weldable than Alloy-247LC and less weldable than IN-617.

[0020] Consumables of other alloys can be made in a similar manner to provide multiple materials to be tested. Another wound consumable 560, illustrated in Fig. 6 is formed by winding three consumables 555 of Alloy-247LC and one consumable 550 of IN-617. The material deposited by this wound consumable 560 is referred to herein as Sieweld-A and is about a 75/25 (by wt. %) mixture of Alloy-247LC and IN-617. Yet another wound consumable is formed by winding two consumables 555 of Alloy- 247LC and one consumable 550 of IN-617. The material deposited by this wound consumable is referred to herein as Sieweld-B and is about a 67/33 (by wt. %) mixture of Alloy-247LC and IN-617.

[0021] Other alloys can be formed in a similar manner by winding consumables having different diameters. For example, winding a 1 mm diameter consumable of IN- 617 with a 2 mm diameter consumable of Alloy-247LC produces an alloy that is about an 80/20 (by wt. %) mixture of Alloy-247LC and IN-617.

[0022] Fig. 7 illustrates one possible way of forming the wound consumables 545, 560. To form the wound consumable 545 the user first fixes one end 565 of the consumables 550, 555 to be wound. Typically, the consumables 550, 555 are held in a vice 570 or clamped to another heavy and essentially immovable object. The opposite ends 575 of the consumables 550, 555 are mounted in a rotatable device 580 such as a drill motor. The rotatable device 580 is then operated to wind the consumables 550, 555 around one another. It is desirable to achieve a tight wind with the smallest gaps possible between the wound consumables 550, 555. Of course, other systems and methods of forming the wound consumables 545, 560 are possible. [0023] Once the wound consumables 545, 560 are formed, the user makes a weld repair or a weld coupon for material and performance testing. Using this system, multiple different alloy chemistries can be quickly welded and tested to arrive at the optimal solution for a particular application.

[0024] The following discussion is an example where the foregoing process was used to manufacture, test, and evaluate welds made with the three alloys discussed (Ductilloy, Sieweld-A, and Sieweld-B) with a base material of Alloy-247LC.

[0025] Referring now to the figures, where the showings are for purposes of illustrating embodiments of the subject matter herein only and not for limiting the same, Figure 1 is a chart 100 illustrating superalloy weldability of various base metal and weld filler materials as a function of their aluminium and titanium content. Generally speaking, the higher the aluminium content of the material the more difficult it is to weld. The line 110 depicts a recognized upper boundary of a zone of weldability. The alloys above this line are recognized as being difficult to weld. For example, as the chart illustrates Alloy-247LC is an alloy that is very difficult to weld while IN-617 is readily weldable with a conventional TIG (tungsten inert gas) welding process. As for weld fillers, the chart also illustrates that HA-282 is readily weldable. To those skilled in the art of welding, HA-282 is a very good ductile weld filler, but it will soon be unable to withstand the oxidation that occurs in the relatively higher operating temperatures of current and future designs of gas turbine engines.

[0026] The alloy Rene-80 is a nickel-based superalloy that is a very popular aircraft engine base metal, however, it has proven to be oxidation limited in current gas turbine usage. IN-617 is a very good ductile nickel-based superalloy weld filler. IN-617 is particularly useful as it has an increase in ductility in the temperature region 700-900°C, a range in which gas turbines operate, whereas most other superalloys have a decrease in ductility in this temperature range.

[0027] The present inventors have recognized that the chemical composition of HA- 282 is essentially a 50/50 (in wt. %) mixture of Rene-80 and IN-617 with some minor differences (the W and Fe contents for example). This is illustrated in Table 1 shown below which lists the chemical compositions of the base metal Rene-80 in line 1, the weld filler IN-617 in line 2, the 50/50 (in wt. %) mixture of Rene-80 and IN-617 in line 3, and weld filler HA-282 in line 4.

Table 1

Thus, (1) HA-282 - Rene-80 + IN-617.

[0028] In current gas turbine castings, Alloy-247LC is a base metal of choice as it can withstand the ever-increasing gas turbine operating temperatures that can make the gas turbine run more efficiently. Thus, the inventors inventively propose to substitute Alloy-247LC for the base metal Rene-80 in the equation (1) to arrive at a new ductile weld filler which is essentially a mixture of the base metal Alloy-247LC and the ductile weld filler IN-617. The inventive ductile weld filler is thus described by equation (2).

(2) Ductile Weld Filler - Alloy-247LC + IN-617.

[0029] The proposed weld filler is a more oxidation resistant weld filler than those weld fillers previously used and thus is much more compatible with currently used base metal alloys, such as Alloy-247LC and IN-738. For example, the properties of ductile weld filler closely match those of the Alloy-247LC and IN-738.

[0030] The proposed ductile weld filler includes the following composition:

11.0 wt% - 15.5 wt% chromium;

9.5 wt% - 11.0 wt% cobalt;

2.0 wt% - 5.0 wt% molybdenum;

4.5 wt% - 7.5 wt% tungsten;

1.5 wt% - 2.6 wt% tantalum;

3.0 wt% - 5.0 wt% aluminum;

0.4 wt% to 1.0 wt% titanium;

at most 0.8 wt% iron;

at most 0.3 wt% manganese;

at most 0.3 wt% silicon;

at most .1 wt% carbon;

at most .015 wt% boron;

at most .02 wt% zirconium;

at most 1.2 wt% hafnium;

at most .1 wt% vanadium;

at most .1 magnesium; and

remainder nickel. [0031] The following table, Table 2, summarizes three exemplary embodiments of the ductile weld filler (details in wt. %), Ductilloy, SieWeld-A-247LC, and SieWeld- B-247LC B including the element ranges and the beneficial effects of each element for the alloy. Ductilloy is essentially a 50/50 (in a wt. %) mixture of Alloy 247 and IN-617. SieWeld-A-247LC essentially includes a 75/25 (in a wt. %) mixture of the base metal Alloy 247 and weld filler IN-617 while SieWeld-B-247LC includes essentially a 66.6/33.3 (in a wt. %) mixture of the base metal Alloy 247 and weld filler IN-617.

Table 2 (all values in wt. %)

[0032] It may be desirable to have a weld filler as closely matched as possible in its composition and properties to the base metal to which it will be welded. For example, by matching the coefficient of thermal expansion of the weld filler to the base material as closely as possible, high stress levels due to differential thermal expansion may be avoided. Thus, the embodiment of the weld filler SieWeld-A-247LC would be the closest match to the base metal Alloy-247 for example. Currently, welds in which a nickel based superalloy base metal and the weld filler are identical attempted at room temperature using conventional welding process are not possible due to the formation of cracks in the heat-affected zone and the weld metal.

[0033] Based on its ductility, or tensile elongation, the proposed ductile weld filler will have good welding properties at room temperature. Furthermore, based on its coefficient of thermal expansion the ductile weld filler will have acceptable performance during turbine operation at elevated temperatures. Figure 2 illustrates the coefficient of thermal expansion of several base metals, Alloy-247LC, IN-738, and Rene 80, weld fillers IN-617, and HA 282, and the proposed weld fillers, Ductilloy, SieWeld-A-247LC and SieWeld-B-247LC. It may be seen in Figure 2 that the coefficient of thermal expansion of the proposed embodiments of the weld filler closely match that of Alloy-247LC. Having a weld filler with a closely matched coefficient of thermal expansion to that of the base metal is advantageous because during a weld procedure when high temperatures are applied to the alloys the materials would heat up similarly. By reducing the temperature difference and therefore the stress gradient between the weld joint and the substrate, cracking may be avoided in the weld joint. [0034] In an embodiment, the deleterious trace elements, which may have a detrimental effect on the properties of the weld filler composition, are held to a tight tolerance. These deleterious trace elements may include silicon, carbon, boron, and zirconium. For example, the percentage of these elements shall not exceed the concentrations as listed in Table 2.

[0035] In an embodiment, the materials Mar-M-247, CM-247LC, PWA-1483, Alloy-247, IN-738, Mar-M002, Rene-N5, Rene-N4, CMSX-4, CMSX-2, Rene-l42, GTD-l l l, MGA-1400, and IN-939 may be welded using the proposed ductile weld filler.

[0036] Referring back to Figures 1 and 2, a method for welding nickel-based superalloy components is proposed. The ductile weld filler as described above is utilized for welding onto a substrate of the nickel-based superalloy component. The method includes applying the ductile weld filler to a surface of the substrate. The proposed ductile weld filler includes a closely matched coefficient of thermal expansion to that of the substrate. Heat may be applied to the weld filler to melt the weld filler forming molten weld filler. At ambient temperature, the molten weld filler is utilized to weld the substrate. The welded substrate is allowed to cool and resolidify whereby a solidified joint is produced on the substrate.

[0037] For the purposes of the disclosure, closely matched refers to having a coefficient of thermal expansion within 3% of Alloy-247LC in the range 600° - l000°C. Typical operating temperatures within a gas turbine may be between 600° - l000°C.

[0038] Figure 3 illustrates a perspective view of a rotor blade 120 or guide vane 130 of a turbo machine, which extends along a longitudinal axis 121. The turbo machine may be a gas turbine of an aircraft or of a power plant for generating electricity, a steam turbine or a compressor. The blade or vane 120, 130 has, in succession along the longitudinal axis 121, a securing region 400, an adjoining blade or vane platform 403 and a main blade or vane part 406. As a guide vane 130, the vane 130 may have a further platform (not shown) at its vane tip 415. A blade or vane root 183, which is used to secure the rotor blades 120, 130, to a shaft or disk (not shaft), is formed in the securing region 400. The blade vane root 183 is designed, for example, in hammerhead form. Other configurations, such as fir-tree or dovetail root, are possible. The blade or vane 120, 130 has a leading edge 409 and a trailing edge 412 for a medium which flows past the main blade or vane part 406. In the case of conventional blades or vanes 120, 130 by way of example, solid metallic materials, in particular superalloys, are used in all regions 400, 403, 406 of the blade or vane 120, 130. Thus, the ductile weld filler may be utilized for welding all the regions of the blade or vane for example. Additionally, other combustion components may also be welded using the proposed ductile weld filler.

[0039] While embodiments of the present disclosure have been disclosed in exemplary forms, it will be apparent to those skilled in the art that many modifications, additions, and deletions can be made therein without departing from the spirit and scope of the invention and its equivalents, as set forth in the following claims.