System, method, and apparatus for repair of components

A method is disclosed including operations for repairing a component. The method includes providing a component including one of titanium and a titanium alloy, providing a laser deposition device, and providing a shielding means that ensures an oxygen content remains below a first threshold and that a water vapor content remains below a second threshold in a target area of the component. The method further includes depositing a metal material on the component, where the depositing includes operating the deposition device along a tool path including a plurality of tool passes, wherein the tool path further comprises a deposition device velocity specification, a laser power specification, and a specified delay time between each of the plurality of tool passes.

TECHNICAL FIELD

The technical field relates generally to repair of titanium parts and more particularly, but not exclusively, repair of titanium parts of a gas turbine engine.

BACKGROUND

The repair of titanium parts through laser deposition, such as metal powder deposition, is known in the art. However, present repair processes suffer from several drawbacks. Currently available processes do not develop a repair with appropriate micro-structure such that the repaired part area maintains the tensile strength and fatigue characteristics of an originally manufactured part. Among the issues with current repair processes, the processes develop micro-porosity in the repaired area, fail to develop sufficient micro-fusion with the substrate of the main part, and introduce thermal peaks and gradients in the nearby part during repair that diminish the part life of the repaired component in the area surrounding the repair. The drawbacks in currently available repair systems are particularly acute in parts that are not amenable to convenient inspection, that operate near the expected working load of the part, and/or that may cause mission failure if the part fails unexpectedly. Accordingly, there is a demand for further improvements in this area of technology.

SUMMARY

One embodiment is a unique laser metal deposition process. Other embodiments include unique methods, systems, and apparatus to repair titanium and titanium alloy components. Further embodiments, forms, objects, features, advantages, aspects, and benefits shall become apparent from the following description and drawings.

DETAILED DESCRIPTION

FIG. 1is a schematic illustration of a system100for repairing titanium components. The system100includes a component102having titanium. The component102may be made out of titanium, a titanium alloy, a cermet including titanium, or other materials including titanium. In one example, the component102is a bladed disk (“blisk”) such as used in a turbine engine. In certain embodiments, the component102includes a non-conforming region104. The non-conforming region104may be a damaged region, a mis-manufactured region, a region with a changed specification relative to the original manufacture of the component102, and/or a region that has not yet been manufactured wherein one step of the manufacture of the component102is a laser metal deposition treatment. Any non-conforming region104requiring material addition for any purpose is also contemplated herein.

The system100further includes a laser deposition device106. Refer to the U.S. patent application entitled “System and method for component material addition,” filed on Jun. 9, 2008 and incorporated by reference herein, for an example of a deposition device usable in certain embodiments of the present application. In certain embodiments, the device106includes a laser108, a metal powder delivery device110, and position actuators112that control the position of the deposition device106. The position of the deposition device106includes an absolute position and/or a position of the deposition device106relative to the component102. For example, the position actuators112control the position of the deposition device106by moving the deposition device106, by moving the component102, and/or by moving another object (not shown) that controls the position of the deposition device106and/or the component102.

The laser deposition device106may utilize metal powder, metal wire, metal ribbon, and/or integral metal with the component102as a feed material for deposition. The laser108includes any laser with a sufficient power and irradiance to perform a metal powder deposition, including without limitation a CO2-based laser and a neodymium-doped yttrium aluminium garnet laser (Nd:YAG). In certain embodiments, the laser108is an Nd:YAG laser or a fiber laser using an impregnated fiber optic cable as the gain media for the laser108. In certain embodiments, a Nd:YAG laser produces a beam with a favorable light wavelength for melting titanium (and/or alloys) powder, reducing the complexity and improving the energy efficiency of the system100. In certain embodiments, the laser104may be a solid state laser. In certain embodiments, the metal powder delivery device110accepts metal powder from a powder storage114, which may be entrained in an inert carrier gas116. In certain further embodiments, the inert carrier gas116is helium.

In certain embodiments, the system100includes a shielding device that ensures an oxygen content remains below a first threshold and that a water vapor content remains below a second threshold in a target area of the component102. The target area includes at least the non-conforming region104, and in certain embodiments the target area includes the entire component102. The shielding device, in certain embodiments, includes an inert gas delivery device118that delivers gas from an inert gas source120to the non-conforming region104at a rate sufficient to meet the oxygen content and water vapor content thresholds. The inert gas source120may be argon, helium, an argon-free gas source, a shared gas source with the inert carrier gas116, or any other inert gas source which is essentially free of oxygen and water vapor. In certain embodiments, the component102may further be sealed, enclosed, and/or partially sealed or enclosed in a container.

In certain embodiments, the first threshold or maximum oxygen content in the target area is about 10 part-per-million (ppm) of oxygen. In certain further embodiments, the first threshold is about 5 ppm oxygen. The allowable oxygen amount depends upon the required component strength and ductility after repair, the formulation of the component material (e.g. certain titanium alloys are more sensitive to oxygen than others). It is a mechanical step for one of skill in the art, considering the features of a specific embodiment and the disclosure herein, to determine a first threshold—for example one of skill in the art may utilize 25 ppm oxygen in the target area, and reduce the first threshold if the process yields a repair with insufficient ductility. The use of 10 ppm, or alternatively 5 ppm, provides adequate results for a wide range of titanium alloys and component102applications.

In certain embodiments, the second threshold may be defined as a dew point temperature, for example a dew point temperature of −55° C. (negative fifty-five degrees Celcius). The thresholds for oxygen fraction and water vapor content depend upon the material formulation of the component102and the powder114or other deposition material, and the temperature and cooling rate of the laser deposition operation. In a component, for example (but without limitation) where the component102will be installed in a location that is not amenable to convenient inspection, where the component102will operate near the expected working load of the component102, and/or where a failure of the component102may cause mission failure if the component102fails unexpectedly, the component102may require high purity and a micro-structure with very little micro-porosity and good micro-fusion, and therefore the first threshold and second threshold may be set very low.

In certain embodiments, the system100further includes an imaging device122that may be structured to observe the non-conforming region104before and/or during a repair operation. For example, the imaging device122may be structured to view the non-conforming region104through the front of the device102and/or through focusing optics (not shown) of the laser108.

In certain embodiments, the system100includes a processing subsystem that includes a controller124. The controller124includes memory, processing, and input/output interfaces. The controller124further includes modules structured to perform operations for repairing a component102. The controller124may be a single device or a plurality of distributed devices, and may include devices that communicate over a network, datalink, wireless communication, and the like. In certain embodiments, the controller124communicates with various sensors and actuators in the system100to send or receive information and to send commands. The communications of the controller124may be direct signals such as electronic, pneumatic, or hydraulic signals, or the communications may be software or datalink parameters.

In certain embodiments, the component102is repaired by the laser deposition device106, and the repaired component has a performance index value greater than 70% of a new component performance index value. The performance index value comprises at least one of a tensile strength value and a fatigue performance value. In certain further embodiments, the repaired component has a performance index value greater than 90% of a new component performance index value. However, other performance index values are contemplated herein.

In certain embodiments, the controller124includes a tool path module, a tool position module, a deposition conditions module, a temperature determination module, and/or a temperature control module. The use of modules emphasizes the structural independence of the aspects of the controller124, and illustrates one grouping of operations and responsibilities of the controller124. Other groupings that execute similar overall operations are understood within the scope of the present application.

FIG. 2is an illustration of a first shielding device202. The first shielding device includes a partial enclosure204and a flow of inert gas206. The partial enclosure204reduces mass transfer in the region of the component102and, combined with sufficient flow of the inert gas206provides an oxygen content below the first threshold and a water vapor content below the second threshold.

FIG. 2Bis an illustration of a second shielding device208. The second shielding device includes a sealed enclosure210and a flow of inert gas212. The sealed enclosure210reduces mass transfer in the region of the component102and, combined with sufficient flow of the inert gas212provides an oxygen content below the first threshold and a water vapor content below the second threshold. The use of a sealed enclosure210may reduce the amount of inert gas212required to maintain the oxygen and water vapor content requirements.

In one embodiment, the shielding device208is a sealed enclosure210filled with a first inert gas, an oxygen scavenger such as a zeolite oxygen adsorber (not shown) that removes trace oxygen from the sealed enclosure210, and an inert gas delivery device118that provides a stream of a second inert gas212. For example, the sealed enclosure210may slowly leak ambient air into the enclosure, and the oxygen scavenger may remove oxygen from the enclosure210and periodically regenerate (e.g. heating to release adsorbed oxygen) and vent trapped oxygen away from the enclosure210.

In certain embodiments, the first inert gas includes argon and/or helium, and the second inert gas includes helium. In certain embodiments, the second inert gas may be argon and/or helium. The selection of each inert gas may depend upon cost and other commercial considerations, and further may depend upon the heat transfer characteristics of each inert gas, and especially the heat transfer characteristics of the second inert gas212that blows directly on the component at the deposition area.

FIG. 2Cis an illustration of a third shielding device214. The third shielding device includes a localized bagging device216. The localized bagging device216reduces mass transfer in the region of the component102and, combined with sufficient flow of the inert gas218provides an oxygen content below the first threshold and a water vapor content below the second threshold. The use of a localized bagging device216may reduce the amount of inert gas218required to maintain the oxygen and water vapor content requirements.

FIG. 3is a schematic block diagram of a controller124. The controller124includes a tool path module302structured to interpret a deposition device tool path304. The tool path module302may interpret the deposition device tool path304by reading the tool path304from communications on a datalink, by looking up the tool path304from a memory location, and/or by calculating the tool path304based on sensed, stored, or communicated parameters. The deposition device tool path304includes a plurality of tool passes306, a deposition device velocity specification308, a laser power specification310, and/or a specified delay time312between each of the plurality of tool passes306.

In certain embodiments, the deposition device tool path304includes at least four tool passes306for each deposition layer applied in repairing the component102. In certain further embodiments, each consecutive tool pass306overlaps a previous tool pass by at least 30%. The use of multiple tool passes306in each deposition layer, combined with other features of the deposition operations described herein, contribute to forming the desired micro-structure in the non-conforming region104at the completion of the deposition. In certain embodiments, the repair area after deposition meets or even exceeds the physical specifications of the base component102, including tensile strength and wear life.

In certain embodiments, the component102is tested after the deposition at a stress load greater than 70% of a maximum expected stress load. For example, if the component102is a blisk for a turbine engine, the turbine engine may be operated at a condition that exceeds a stress load of 70% of a maximum expected stress load on the blisk—which in typical engines will be an operating point that significantly exceeds 70% of the rated turbine engine power.

In certain further embodiments, a performance index is determined for the component102and/or for a deposit coupon of the component102. The deposit coupon may be material created during the deposition operation and under the same conditions as the deposition operation, where the deposit coupon may be tested for a performance index after the repair. The use of a deposit coupon allows a performance estimate of the repaired component102without subjecting the component102to wear or damage from the test, and allows more complete testing including destructive testing of the deposit coupon.

In certain embodiments, the performance index is a description representative of the component102tensile strength, fatigue capability, or similar characterization of the component102as specified for the application. In certain embodiments, it is determined whether the performance index for the component102exceeds a performance threshold, where the performance threshold is a threshold greater than 70% of a new component performance index. For example, the performance index may be an exhibited tensile strength of the repaired component, and the performance threshold may be a value of 70% of the tensile strength of a newly manufactured component. Depending upon the application, the performance threshold may be greater than about 90% of a new component performance index.

In certain embodiments, the deposition device velocity specification308, the laser power specification310, and the specified delay time312are configured such that the deposited metal material cools at a cooling rate between a low cooling rate314and a high cooling rate315. The cooling rate of the deposited material and the presence or lack of impurities in the gases surrounding the deposition operation determine the final micro-structure of the repaired component. In certain embodiments, the development of micro-porosity and/or the development of a grain boundary alpha phase indicate a cooling rate that is too low and/or the presence of impurities. Impurities can be detected directly and can thereby be eliminated as a cause or mitigated by better removal. The cooling rate can be adjusted by changing the laser power specification310, the specified delay time312, the deposition device velocity specification308, and/or the powder delivery rate324.

The cooling rate during the deposition depends upon the deposition device velocity, the laser power utilized, the delay time between tool passes306, the ability of the component material to absorb the laser104utilized (e.g. titanium absorbs Nd:YAG energy in greater percentages than a CO2based laser), and the thickness of the material (thicker material heats up more slowly and cools down more slowly). The control of the laser power utilized can be either by a direct laser power command (e.g. 175 Watts) and/or a by utilizing a pulse-width modulated (PWM) laser. For example, where a laser has a 350 Watt base power and 175 Watts are needed, a PWM duty cycle of 50% provides a net power of 175 Watts continuous.

In certain embodiments, and especially in embodiments with critical components and/or where material purity of the component102is important, the deposition device102does not include a copper chill. It is a mechanical step for one of skill in the art to control the available parameters in light of the fixed parameters and the disclosure herein. For example, the component thickness is generally not a controllable parameter because the component102design is typically, but not necessarily, specified before the deposition device tool path304is determined. Similarly, the type of laser and component material, and therefore the absorption coefficient, is typically specified before the deposition device tool path304is determined.

The laser power specification310can be calculated in real-time, and changed during operations based on, for example, a deposited material representative temperature318provided by a temperature sensor126(refer toFIG. 1). The deposition device tool path304may be calculated before operations begin, may be determined at least partially in a “teach-and-learn” operation where an operator controls the deposition device102through the spatial path to be followed during deposition operations while the controller124records the spatial parameters, and may further be adjusted based on calculated or measured parameters during deposition operations.

The controller124, in certain embodiments, includes a tool position module320that controls the position actuators112in response to the deposition device tool path304. In certain embodiments, the tool position module320interprets a current deposition device position328and provides position actuator commands330. The controller124further includes a deposition conditions module322that controls a powder delivery rate324and a laser power value326in response to the deposition device tool path304and the deposition device position328.

For example, the deposition device tool path304may specify a variable laser power value along a length of the tool passes306, and the deposition conditions module322provides the specified laser power value at each position328according to the deposition device tool path304. In certain further embodiments, the deposition device velocity specification308may likewise vary along a length of the tool pass306. Further, the laser power value326and the deposition device velocity specification308may vary from one tool pass306to a later tool pass306. As described, the laser power value326depends upon many factors and tradeoffs, but generally a laser power value326greater than 50 Watts will provide sufficient power for deposition as described. In certain embodiments, the laser104has a power output between about 50 Watts and about 2,000 Watts, although higher values may be utilized in certain embodiments. In certain further embodiments a laser power value326is below about 500 Watts.

In certain embodiments, the controller124includes a temperature determination module332that interprets the deposited material representative temperature318. The temperature determination module332interprets the deposited material representative temperature318by reading a value from a sensor126, by reading a value from a memory location, by interpreting an electronic signal such as a voltage, and/or by calculating the deposited material representative temperature318utilizing other parameters available in the system100.

The deposited material representative temperature318may be any temperature in the system100indicative of the temperature of the deposited material, including a melt pool temperature and/or temperature of the component102at a location in some thermal contact with the deposited material. The deposited material representative temperature318may generally be correlated to the cooling rate of the deposited material—for example a higher peak temperature generally provides a lower cooling rate, and the cooling rate of the deposited material may be directly tracked in a feedback manner utilizing the deposited material representative temperature318. The temperature and/or cooling rate of the deposited material may be correlated to the deposited material representative temperature318by a function, a lookup table based on several sample data points, or through similar methods understood in the art.

In certain further embodiments, the controller124includes a temperature control module334that interprets a low cooling rate314and a high cooling rate315, and the tool position module320controls the position actuators112in response to the deposited material representative temperature318and the low cooling rate314and a high cooling rate315. For example, the tool position module320may issue position actuator commands330to decrease the velocity of the deposition device102in response to the deposited material representative temperature318indicating that the deposited material cooling rate is approaching the high cooling rate315. In certain further embodiments, the deposition conditions module322controls the powder delivery rate324and/or the laser power value326in response to the deposited material representative temperature318and the low cooling rate314and a high cooling rate315. For example, the deposition conditions module322may increase the powder delivery rate324and/or increase the laser power value326in response to the indicating that the deposited material cooling rate is approaching the high cooling rate315.

FIG. 4is an illustration400of a component thickness406and laser power value310associated with an axial position410of a non-conforming area104. The deposition device tool path304may provide a laser power value specification310which, in one example, is provided as a laser power value326as a function of an axial position410through the non-conforming area104. The non-conforming area104includes a first axial end402and a second axial end404, with values for the laser power value326specified throughout. The laser power value specification310may be a nominal specification, adjusted by the temperature sensor126feedback, for example. The thickness curve406is shown for illustration of how the material thickness of the component102may vary through the non-conforming region. Further, the thickness curve406may vary with each subsequent deposition layer (not shown) as the contours of the built-up component102change.

FIG. 5is a schematic flow chart diagram illustrating a procedure500for repairing a titanium component102. The procedure500includes an operation502to provide a titanium and/or titanium alloy component. The procedure500further includes an operation to provide laser deposition device102. The procedure500further includes an operation506to provide a shielding means. The procedure500further includes an operation508to deposit a metal powder on the component by operating a laser deposition device102along a tool path304. In certain embodiments, the procedure500includes an operation510to determine a performance threshold, an operation512to determine a performance index, and an operation514to compare the performance index to the performance threshold.

FIG. 6is a schematic flow chart diagram illustrating an operating process600of a controller124. The process600includes an operation602to interpret a deposition device tool path304and an operation604to interpret a low cooling rate314and a high cooling rate315. The process600further includes an operation606to interpret a deposited material representative temperature318. The process600further includes an operation608to control position actuators112, to control a powder delivery rate324, and/or to control the laser power value326in response to the deposition device tool path304, the low cooling rate314and a high cooling rate315, and the melting pool temperature318.

As is evident from the figures and text presented above, a variety of embodiments according to the present invention are contemplated.

A method is disclosed including operations for repairing a component. The method includes providing a component including one of titanium and a titanium alloy, providing a laser deposition device, and a shielding the component to ensure an oxygen content remains below a first threshold and that a water vapor content remains below a second threshold in a target area of the component. The method further includes depositing a metal material on the component, wherein the depositing includes operating the deposition device along a tool path including a plurality of tool passes, wherein the tool path further comprises a deposition device velocity specification, a laser power specification, and may further include a specified delay time between each of the plurality of tool passes. In certain embodiments, the method further includes testing the component at a stress load greater than 70% of a maximum expected stress load.

In certain embodiments, the component comprises a bladed disk. In certain embodiments, the laser has a power output between about 50 Watts and 2,000 Watts, and in certain further embodiments includes a power output below about 500 Watts. In certain embodiments, the laser is a solid state laser, a fiber laser, and/or an Nd:YAG laser.

In certain embodiments, the tool path includes at least four tool passes for each of at least one deposition layer. In certain embodiments, each of the plurality of tool passes overlays a previous tool path by at least 30%. In certain embodiments, the laser power specification includes a variable laser power value along a length of at least one of the tool passes. In certain embodiments, the deposition device velocity specification, a laser power specification, and a specified delay time between each of the plurality of tool passes are configured such that the deposited metal material cools at a cooling rate between a low cooling rate and a high cooling rate.

In certain embodiments, the shielding means includes a helium gas stream, a localized bagging device, a partial enclosure, and/or a sealed enclosure. In certain embodiments, the first threshold is not greater than about 10 ppm, and in certain further embodiments not greater than about 5 ppm. In certain further embodiments, the second threshold includes a dew point of about −55° C. In certain embodiments, the shielding means includes an argon-free inert gas delivery means.

A system is disclosed including a component including titanium, where the component has a non-conforming region. The system further includes a laser deposition device including a laser, a metal powder delivery device, and a plurality of position actuators structured to control a position of the deposition device. The system further includes a shielding means that ensures an oxygen content remains below a first threshold and that a water vapor content remains below a second threshold in a target area of the component. In certain embodiments, the system includes a controller having modules configured to functionally execute operations to repair the component.

In certain embodiments, the controller includes a tool path module structured to interpret a deposition device tool path, where the deposition device tool path includes a plurality of tool passes, a deposition device velocity specification, a laser power specification, and a specified delay time between each of the plurality of tool passes. In certain further embodiments, the controller includes a tool position module structured to control the position actuators in response to the deposition device tool path, and a deposition conditions module structured to control a powder delivery rate and a laser power value in response to the deposition device tool path and the deposition device position.

In certain embodiments of the system, the deposition device does not include a copper chill. In certain further embodiments, the laser having a power output between about 50 Watts and 2,000 Watts, and in certain embodiments the laser has a power output below about 500 Watts. In certain embodiments, the laser is a solid state laser, a fiber optic laser, and/or an Nd:YAG laser.

In certain embodiments, the controller further includes a temperature determination module structured to interpret a deposited material representative temperature and a temperature control module structured to interpret a low cooling rate and a high cooling rate, and the tool position module is further structured to control the position actuators in response to the deposited material representative temperature and the low cooling rate and a high cooling rate. In certain embodiments, the controller further includes a temperature determination module structured to interpret a deposited material representative temperature, and a temperature control module structured to interpret a low cooling rate and a high cooling rate, and the deposition conditions module is further structured to control the powder delivery rate and/or the laser power value in response to the deposited material representative temperature and the low cooling rate and a high cooling rate.

An apparatus is disclosed including a laser deposition device including a laser, a metal material delivery device, and a plurality of position actuators structured to control a position of the deposition device. The apparatus further includes shielding means that ensures an oxygen content remains below a first threshold and that a water vapor content remains below a second threshold in a target area of the component. In certain embodiments, the apparatus includes a controller having a plurality of modules to functionally execute a procedure to repair a component.

In certain embodiments, the controller includes a tool path module structured to interpret a deposition device tool path, where the deposition device tool path includes a plurality of tool passes, a deposition device velocity specification, a laser power specification, and a specified delay time between each of the plurality of tool passes. In certain further embodiments, the controller includes a tool position module structured to control the position actuators in response to the deposition device tool path, and a deposition conditions module structured to control a powder delivery rate and a laser power value in response to the deposition device tool path and the deposition device position.

In certain embodiments, the shielding means includes a helium gas stream, a localized bagging device, a partial enclosure, and a sealed enclosure. In certain embodiments, the shielding means includes an argon-free inert gas delivery means. In certain embodiments, the deposition device velocity specification, the laser power specification, and the specified delay time between each of the plurality of tool passes are configured such that the deposited metal material cools at a cooling rate between a low cooling rate and a high cooling rate.

In certain embodiments, the tool path further includes at least four tool passes for each of at least one deposition layer. In certain further embodiments, each of the plurality of tool passes overlays a previous tool path by at least 30%.