Patent Application
20130323533
The subject matter disclosed herein relates to superalloy components and, more specifically, to repairing superalloy components using single crystal coupons.
Nickel-base and cobalt-base superalloys can be used in many high temperature demanding environments such as hot gas path locations of gas turbines. The superalloy components can provide strong and sustained mechanical performance despite the consistent presence of elevated temperatures. However, the superalloy components may still experience some damage to corrosion, erosion, fatigue or other general wear. In even some instances, new-make superalloy components may require repair to fill in voids left from casting operations and/or be joined with other superalloy components to produce a finished product.
While traditional alloys may be welded to repair such defects or enable such joining, welding superalloys can result in strain age cracking and/or liquidation cracking. High energy density welding through electron beam welding or laser beam welding can reduce the amount of cracking in the weld area of the superalloy component. However, some repairs may require the filling of large volume voids with potentially irregular shapes. Moreover, even while gas tungsten arc welding may be used for large volume build-ups, gas tungsten arc welding can still result in cracking when welding such high gamma prime superalloys.
Accordingly, alternative repaired superalloy components and methods for repairing superalloy components would be welcome in the art.
In one embodiment, a method for repairing a superalloy component is provided. The method includes disposing a single crystal coupon in a void of the superalloy component, disposing one or more shims between the single crystal coupon and the superalloy component, and, welding the one or more shims to join with the single crystal coupon and the superalloy component using a high energy density beam welder.
In another embodiment, a repaired superalloy component is provided. The repaired superalloy component includes a single crystal coupon disposed in a void of the repaired superalloy component, and one or more welded shims disposed between and joining the single crystal coupon and the repaired superalloy component, wherein the one or more welded shims were welded using a high energy density beam welder.
These and additional features provided by the embodiments discussed herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.
The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the inventions defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.
Superalloy components with single crystal coupons disclosed herein may generally comprise a superalloy component that had one or more defects repaired therefrom. The one or more defects can be excavated from the superalloy component to create a void. A single crystal coupon may then be placed in the void and one or more shims may be disposed between the single crystal coupon and the superalloy component. The one or more shims may then be welded using a high energy density beam welder to join with the single crystal coupon and the superalloy component. Superalloy components with single crystal coupons and methods for repairing superalloy components will be discussed in more detail herein.
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For example, in some embodiments, the superalloy component 10 can comprise nickel-based superalloys such as René N4™, René N5™, René 108™, GTD-111®, GTD-222®, GTD-444® and IN-738. René N4™, René N5™, René 108™, GTD-111®, GTD-222® and GTD-444® comprise gamma prime-strengthened nickel-based superalloys whose compositions are reported in various literature, including U.S. Pat. Nos. 4,810,467, 5,154,884, 5,399,313, 6,074,602, 6,416,596, 6,428,637, and others. The nominal composition of IN-738 is reported as, by weight, about 16% chromium, 8.5% cobalt, 1.75% molybdenum, 2.6% tungsten, 1.75% tantalum, 0.9% niobium, 3.4% aluminum, 3.4% titanium, 0.10% zirconium, 0.01% boron, 0.17% carbon, the balance nickel and impurities. In some embodiments, the superalloy component can comprise cobalt-base superalloys such as FSX-414. The nominal composition of FSX-414 is, by weight, about 29.5% chromium, 10.5% nickel, 7% tungsten, up to 2% iron, 0.25% carbon, and 0.012% boron, the balance cobalt and incidental impurities. The superalloy component 10 can also comprise a variety of parts for different applications. For example, in some embodiments the superalloy component 10 can comprise a hot gas path turbine component such as a bucket, vane, nozzle or any other turbine component that may be subjected to elevated temperatures during operation.
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The single crystal coupon 20 can comprise any single crystal material including the same material as, or a material similar in composition to, the superalloy component 10. For example, in some embodiments, the single crystal coupon 20 can comprise René N5™. The single crystal coupon 20 can comprise any shape that is complimentary to the void 19 such that the single crystal coupon 20 substantially fills in the missing superalloy component 10. For example, where the void 19 comprises a substantially geometric shape such as that discussed above and illustrated in
Furthermore, the single crystal coupon 20 can be provided or machined to provide a close fit with the void 19 such that the addition of one or more shims 30 secures the single crystal coupon 10 in place. For example, in some embodiments the single crystal coupon 10 can be sized such that it fills the void to only leave a gap of less than about 0.3 cm, less than about 0.2 cm, less than about 0.1 cm, less than about 0.05 cm or even less than about 0.125 cm. In some embodiments, at least one of the one or more shims can comprise a thickness of between about 0.38 mm to about 1.02 mm.
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For example, in one embodiments, at least one of the one or more shims 30 can comprise a composition of from about 9 percent to about 16 percent chromium, from about 7 percent to about 14 percent cobalt, from about 10 percent to about 20 percent molybdenum, from about 1 percent to about 5 percent iron, from about 0.05 percent to about 0.75 percent aluminum, from about 0.5 percent to about 2 percent titanium, from about 0.02 percent to about 0.1 percent carbon, from about 0.55 percent to about 2.75 percent combined titanium and aluminum, and the balance nickel. In some embodiments, at least one of the one or more shims 30 can comprise a composition of about 12.5 percent chromium, about 10.5 percent cobalt, about 15 percent molybdenum, about 3 percent iron, about 0.25 percent aluminum, about 1.1 percent titanium, about 0.06 percent carbon, about 1.65 percent combined titanium and aluminum and the remainder nickel. Such compositions may be realized by any operable alloying method.
Moreover, the size and shape of the one or more shims 30 can depend on the size and shape of the void 19 and the single crystal coupon 20. In some embodiments, the one or more shims 30 can extend past the surface 16 of the superalloy component 10 such as illustrated in
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The operating parameters of the high energy density beam welder 40 can vary depending on the size, shape and material of the one or more shims 30. For example, in some embodiments, such as when an electron beam welder is used, a voltage of between about 100 kV and about 130 kV may be used with a current of between about 25 mA to about 35 mA. In some embodiments, even higher voltages and/or currents may be used to ensure full penetration thereby reducing the possibility of earlier cyclic fatigue of the joint. Similarly, the travel speed of the electron beam welder may comprise from about 50 cm per minute to about 75 cm per minute and may be controlled to vary the intensity of the beam based on the size, shape and location of the one or more shims 30. It should be appreciated that the travel speed of the high energy density beam should not drop too low as to overheat and potentially damage the joint, nor rise too high to prevent full penetration of the weld. In some embodiments, other high density beam welding parameters may be tailored to the given weld such as oscillation, frequency and/or focus.
After the one or more shims 30 are welded with the high energy density beam welder in step 130, the superalloy component 10 may optionally undergo any subsequent post-welding treatment. For example, in some embodiments the superalloy component 10 may be undergo a post weld heat treatment to assist in relieving stress from the weld. In some embodiments, the superalloy component 10 may be machined such as to remove excess material (e.g., material from the one or more shims 30) or ensure a smooth surface around the single crystal coupon 20. In even some embodiments, the superalloy component 10 may undergo non-destructive evaluation (e.g., fluorescent penetration inspection, ultrasonic testing, etc.) to ensure the final repaired part is structurally sound.
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A superalloy component was repaired using a single crystal coupon and a shim using the methods disclosed herein. The superalloy component comprised René 108™ and the single crystal coupon comprised René N5™. A 4 mm shim was disposed between the single crystal coupon and the superalloy component. The shim had a composition of about 12.5 percent chromium, about 10.5 percent cobalt, about 15 percent molybdenum, about 3 percent iron, about 0.25 percent aluminum, about 1.1 percent titanium, about 0.06 percent carbon, about 1.65 percent combined titanium and aluminum and the remainder nickel. The shim was then welded using a laser beam welder and post weld heat treated at 1205° C. for 2 hours.
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While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
