Method for curing selected portion of metal article, additive manufacturing system related thereto, and metal article

Abstract

To provide a method for curing a selected portion of a metal object, an additive manufacturing system related thereto, and a metal article.SOLUTION: A method for curing a selected portion of a metal article includes the steps of: establishing a non-reactive atmosphere within a build chamber of an additive manufacturing system; using an energy source to melt a metal material and deposit the molten material in layers to build the metal article; and establishing a reactive atmosphere within the build chamber to cause a chemical reaction to cure a portion of a plurality of selected layers. The additive manufacturing system for curing the selected portion of the metal article includes a build chamber, a material handling assembly, a substrate, an energy source assembly, a translation assembly, and a system control assembly. The metal article includes a layer of metal materials deposited through the additive manufacturing process.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure generally relates to hardening selected portions of a metal article using additive manufacturing processes, including hardening precise internal locations of the metal article. The present disclosure also relates to surface hardening of precise surface locations of the metal article, and providing precise hardening depths limited only by the size of the metal article. Various techniques are also contemplated for switching between reactive atmospheres for hardening portions of the metal article and non-reactive atmospheres where the portions of the metal article are not hardened. Additionally, various techniques are also contemplated for controlling material handling, energy sources, reactive and non-reactive gases. [Background technology]

[0002] Current surface hardening methods that modify the surface composition require heat treatment equipment as well as significant pre- and post-treatment of the components. Titanium alloys currently do not have an effective surface hardening process developed to allow for the replacement of steel in many product applications. Existing surface hardening techniques for titanium have limitations regarding the surface hardened depth and the location of the surface hardening on the part. Existing surface hardening techniques are furnace-based surface hardening processes that require long durations in high temperature furnaces, which can create undesirable grain growth in the alloy and risk distortion of the part due to long exposure at process temperatures.

[0003] Current additive manufacturing technologies do not include gas control systems to precisely define the curing gas composition in the molten pool. Current equipment does not allow for multiple partial pressures of gases in the build chamber. Thus, existing equipment does not allow for a reliable curing approach. Summary of the Invention [Problem to be solved by the invention]

[0004] Accordingly, those skilled in the art continue to undertake research and development efforts to improve techniques for precisely hardening metal articles during additive manufacturing processes. [Means for solving the problem]

[0005] Examples of methods for hardening selected portions of a metal article, metal articles, and additive manufacturing systems for hardening selected portions of a metal article are disclosed. For example, a metal article having hardened selected portions may be constructed in its entirety using additive manufacturing methods, or an existing metal article produced using other techniques may have hardened material selectively added using additive manufacturing methods. The following is a non-exhaustive list of examples, some of which may be claimed, of subject matter according to the present disclosure.

[0006] In one example, a disclosed method for hardening selected portions of a metal article includes: (1) establishing a non-reactive atmosphere in a build chamber of an additive manufacturing system; (2) melting the metal material using an energy source to deposit the molten material in multiple layers to build the metal article in conjunction with controlling translational motion of at least one of the metal article and the energy source based on predetermined locations for depositing the molten material; and (3) selectively establishing a reactive atmosphere in the build chamber in conjunction with the melting and subsequent solidification of the molten material to produce a chemical reaction to harden at least one selected portion of each layer in multiple selected layers of the multiple layers.

[0007] In one example, a disclosed additive manufacturing system for curing a selected portion of a metal article includes a build chamber, a material handling assembly, a substrate, an energy source assembly, a translation assembly, and a system control assembly. The build chamber is configured to provide a controlled environment for additive manufacturing of the metal article. The material handling assembly is configured to supply a metal material within the build chamber in conjunction with an additive manufacturing process. The substrate is configured to at least temporarily hold the metal article during the additive manufacturing process. The energy source assembly is configured to melt the metal material using an energy source and deposit the molten material in multiple layers to build the metal article on the substrate. The translation assembly is configured to provide translational motion of at least one of the substrate and the energy source assembly based on a predetermined location for depositing the molten material in conjunction with the additive manufacturing process. The system control assembly is in operative communication with the material handling assembly, the energy source assembly, and the translation assembly. The system control assembly is configured to control the establishment of a non-reactive atmosphere in the build chamber, configured to control the supply of metallic material by the material handling assembly, configured to control the melting of the metallic material by the energy source in conjunction with the control of the translation assembly, and configured to control the selective establishment of a reactive atmosphere in the build chamber in conjunction with the melting and subsequent solidification of the molten material to harden by chemical reaction at least one selected portion of each layer in a plurality of selective layers of the plurality of layers.

[0008] In one example, the disclosed metal article includes multiple layers of a metal material deposited in layers by an additive manufacturing process, where at least a selected portion of each layer within a plurality of selected layers of the plurality of layers is hardened by a chemical reaction caused by a reactive atmosphere selectively established during a selected period of the additive manufacturing process, and the remaining portions of the plurality of selected layers and the remaining layers of the plurality of layers were deposited during the remaining period of the additive manufacturing process in which a non-reactive atmosphere was established.

[0009] Other examples of the disclosed methods for hardening selected portions of a metal article, metal articles and additive manufacturing systems for hardening selected portions of a metal article will become apparent from the following detailed description, the accompanying drawings, and the appended claims. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a flow diagram of an example method for hardening selected portions of a metal article. [Diagram 2] FIG. 1 is a functional stackup diagram of an example metal article. [Diagram 3] FIG. 2 is a flow diagram of another example method for hardening selected portions of a metal article in combination with FIG. 1 . [Figure 4] FIG. 4 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIGS. 1 and 3 . [Diagram 5] FIG. 2 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIG. 1 . [Figure 6] FIG. 2 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIG. 1 . [Figure 7] FIG. 7 is a flow diagram of another example method for hardening selected portions of a metal article in combination with FIGS. 1 and 6. [Figure 8] FIG. 7 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIGS. 1, 4 and 6. [Figure 9] FIG. 5 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIGS. 1 and 4. [Figure 10] FIG. 2 is a flow diagram of yet another example method for hardening selected portions of a metal article in combination with FIG. 1 . [Figure 11] FIG. 2 is a flow diagram of another example method for hardening selected portions of a metal article in combination with FIG. 1 . [Figure 12] FIG. 1 is a functional block diagram of an example of an additive manufacturing system for hardening selected portions of a metal article. [Figure 13] FIG. 13 is a functional block diagram of an example gas manifold assembly for the additive manufacturing system of FIG. [Figure 14] FIG. 14 is a functional block diagram of an example of a first configuration of the gas manifold assembly of FIG. 13. [Figure 15] FIG. 14 is a functional block diagram of an example of a second configuration of the gas manifold assembly of FIG. [Figure 16] FIG. 14 is a functional block diagram of an example of a third configuration of the gas manifold assembly of FIG. [Figure 17] FIG. 14 is a functional block diagram of an example of a fourth configuration of the gas manifold assembly of FIG. [Figure 18] FIG. 14 is a functional block diagram of an example of a fifth configuration of the gas manifold assembly of FIG. [Figure 19] FIG. 13 is a functional block diagram of an example build chamber of the additive manufacturing system of FIG. [Figure 20] FIG. 1 is a block diagram of an aircraft manufacturing and service methodology. [Figure 21] FIG. 1 is a schematic diagram of an aircraft. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Referring generally to Figures 1-12, by way of example, the present disclosure relates to methods 100, 300, 400, 600, 700, 800, 900, 1000, 1100 for hardening selected portions of a metal article 200. Figure 1 discloses an example of the method 100. Figure 2 discloses an example of the metal article 200. Figures 1 and 3 disclose an example of the method 300. Figures 1, 3, and 4 disclose an example of the method 400. Figure 5 discloses an example of forming a molten pool in connection with the method 100. Figures 1 and 6 disclose an example of the method 600. Figures 1, 6, and 7 disclose an example of the method 700. Figures 1, 4, 6, and 8 disclose an example of the method 800. Figures 1, 4, and 9 disclose an example of the method 900. Figures 1 and 10 disclose an example of the method 1000. Figures 1 and 11 disclose an example of a method 1100. Figure 12 discloses various examples of an additive manufacturing system 1200.

[0012] 1, 2, and 12, in one or more examples, a method 100 for hardening a selected portion of a metal article 200 includes establishing 102 a non-reactive atmosphere 1228 in a build chamber 1202 of an additive manufacturing system 1200. At 104, an energy source 1216 is used to melt a metal material 1208 and deposit the molten material in a plurality of layers 202 to build the metal article 200 in conjunction with controlling translational motion of at least one of the metal article 200 and the energy source 1216 based on predetermined locations for deposition of the molten material. At 106, a reactive atmosphere 1230 is selectively established in the build chamber 1202 such that a chemical reaction melts 104 at least one selected portion 204 of each layer in a plurality of selected layers 206 of the plurality of layers 202 and hardens in conjunction with subsequent solidification of the molten material. For example, a metal article having selected portions that are hardened may be constructed in its entirety using additive manufacturing, or an existing metal article produced using other techniques may have hardened material selectively added using additive manufacturing. In other examples, a vacuum may be applied first to establish the appropriate environment.

[0013] In another example of the method 100, the non-reactive atmosphere 1228 includes at least one inert gas 1220. In a further example, the at least one inert gas 1220 includes argon, helium, neon, nitrogen, or any other suitable inert gas in any suitable combination. For example, nitrogen can be used as a non-reactive gas or an inert gas for certain metallic materials. However, nitrogen may be a reactive gas for other metallic materials, such as titanium. In yet another example of the method 100, for an additive manufacturing process, the metallic material 1208 includes metal powder, metal wire, or any other suitable metallic material in any suitable combination. In yet another example of the method 100, the metallic material 1208 includes titanium, titanium alloy, steel, corrosion resistant steel, precipitation hardened corrosion resistant steel, maraging steel, steel alloy, or any other suitable metallic material in any suitable combination. In yet another example of the method 100, the energy source 1216 includes at least one laser beam, at least one electron beam, at least one plasma arc, or any other suitable energy source in any suitable combination.

[0014] In various examples, the depth of a given layer of the plurality of layers 202 deposited during an additive manufacturing process is between about 0.0001 inches and about 0.001 inches, between about 0.001 inches and about 0.002 inches, between about 0.002 inches and about 0.004 inches, between about 0.004 inches and about 0.010 inches, between about 0.010 inches and about 0.020 inches, or any other suitable depth range for an additive manufacturing process. The minimum depth of a given layer is based on the minimum deposition thickness. The deposited thickness may be based on at least one of the metallic material feedstock size and the energy provided to form the melt pool. For example, an additive manufacturing energy source may be used for "smoothing" and a reactive atmosphere may be used to deposit a very thin hardened layer on the metal article. In various other examples, the reactive atmosphere 1230 may include a mixture in which the reactive gas ranges from about 0.1% to about 50%, from about 0.2% to about 40%, from about 0.5% to about 30%, from about 0.8% to about 20%, from about 1.0% to about 10%, or any other suitable reactive gas percentage. For example, higher percentages for the mixture are contemplated if a higher reactive gas percentage (e.g., greater than 50%) is suitable for a given operation.

[0015] In another example of the method 100, the translational motion of the metal article 200, the translational motion of the energy source 1216, the operation of the energy source 1216, or any other suitable parameter of any suitable combination, is controlled to manage a chemical reaction that hardens at least one selected portion 204 of the plurality of selected layers 206 of the metal article 200. In a further example, the at least one parameter of the energy source 1216 and the translational motion of the metal article 200 and / or the energy source 1216 includes an energy source dwell time of a selected predetermined location for hardening at least one selected portion 204 of each layer in the plurality of selected layers 206 of the metal article 200, a laser deposition dwell time associated with the energy source 1216, a plasma arc dwell time associated with the energy source (1216), an electron beam dwell time associated with the energy source 1216, or any other suitable parameter of any suitable combination. The control of the translational motion, the operation of the energy source, and the corresponding parameters can be based on a three-dimensional digital model 1232 of the metal article 200.

[0016] In yet another example of method 100, the translational motion of metal article 200 and / or energy source 1216 includes controlling linear motion in at least one of an X-axis, a Y-axis, and a Z-axis. In a further example, the translational motion of metal article 200 and / or energy source 1216 includes controlling rotational motion relative to at least one of an X-axis, a Y-axis, and a Z-axis. In another further example, the translational motion of metal article 200 and / or energy source 1216 includes controlling angular motion relative to at least one of an X-axis, a Y-axis, and a Z-axis. In yet another example of method 100, the predetermined location for deposition of molten material is based on a three-dimensional digital model 1232 of metal article 200.

[0017] In yet another example of the method 100, the reactive atmosphere 1230 includes a predetermined reactive gas mixture 1227 of at least one inert gas 1220 and at least one reactive gas 1224. In a further example, the chemical reaction includes nitridation. In a further example, the at least one reactive gas 1224 includes nitrogen gas, a nitrogen-based gas, ammonia gas, or any other suitable reactive gas in any suitable combination. In another further example, the chemical reaction includes carbonization. In a further example, the at least one reactive gas 1224 includes a carbon-based gas, acetylene gas, propane gas, butane gas, methane gas, carbon monoxide gas, or any other suitable reactive gas in any suitable combination. If the reactive gas or by-products of the chemical reaction produce hazardous gas mixtures, the process is managed by at least one of the use of vacuum, partial pressure, inert gas purging, and a gas safety control system. In another example of the method 100, each selected portion 204 of the metal article 200 to be hardened is based on a corresponding location within the three-dimensional digital model 1232 of the metal article 200 designated for hardening.

[0018] In yet another example of the method 100, at least one selected portion 204 of each layer of the plurality of selected layers 206 of the metal article 200 to be hardened includes one or more regions where a portion of the continuous layer is hardened. In a further example, the portion of the continuous layer to be hardened includes at least one portion having a hardening depth in the range of about 0.0001 inches deep through the metal article 200, about 0.002 inches deep through the metal article 200, about 0.004 inches deep through the metal article 200, about 0.006 inches deep through the metal article 200, about 0.008 inches deep through the metal article 200, about 0.010 inches deep through the metal article 200, about 0.020 inches deep through the metal article 200, about 0.030 inches deep through the metal article 200, about 0.040 inches deep through the metal article 200, or any other suitable range of hardening depths. In another further example, the one or more regions include at least one region of the interior of the metal article 200 that does not extend to an outer surface of the metal article 200. In yet another further example, the one or more regions include at least one region that extends from a first layer to a successive layer of the metal article 200. As discussed above, the metal article 200 can be constructed with an intermittently hardened internal structure to meet any design requirements at the deposited layer level. For example, the metal article 200 can include an internal region that forms a metal matrix composite. In yet another further example, the one or more regions include at least one region that extends from an inner layer of the metal article 200 to an outer surface of the metal article 200 such that a portion of the metal article 200 is case hardened. In a further example, the portion of the metal article 200 that is case hardened includes at least one portion having a case hardening depth greater than at least one of about 0.0001 inches, about 0.001 inches, about 0.010 inches, about 0.020 inches, about 0.030 inches, and about 0.040 inches, or any other suitable case hardening depth.

[0019] In yet another example of the method 100, the step 106 of selectively establishing a reactive atmosphere 1230 precedes the step 102 of establishing a non-reactive atmosphere 1228. In yet another example of the method 100, the steps 102 of establishing a non-reactive atmosphere 1228 and the step 106 of selectively establishing a reactive atmosphere 1230 are repeated during the step 104 of melting the metallic material 1208, depositing the molten material in multiple layers 202 until the metallic article 200 is completed.

[0020] 1-3 and 12, in one or more examples, a method 300 for hardening a selected portion of a metal article 200 also includes the method 100 of FIG 1. The method 300 begins at step 302 of receiving at least one inert gas 1220 from at least one first gas source 1222. At 304, the at least one inert gas 1220 is delivered to the build chamber 1202 to establish a non-reactive atmosphere 1228. The method 300 continues from 304 to 102 of the method 100.

[0021] In another example, the method 300 continues from 302 to step 306 of opening an exit path 1236 from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with delivering at least one inert gas 1220 to the build chamber 1202. The method 300 continues from 306 to 102 of the method 100.

[0022] In yet another example of method 300, the gaseous contents 1238 purged from the build chamber 1202 include air, one or more reactive gases, one or more inert gases, or any other gases that may be present in the build chamber 1202 in any suitable combination.

[0023] In yet another example of the method 300, the exit path 1236 from the build chamber 1202 remains open during the additive manufacturing process to allow a continuous flow of the at least one inert gas 1220 into the build chamber 1202.

[0024] 1-4 and 12, in one or more examples, a method 400 for hardening a selected portion of a metal article 200 also includes methods 100, 300 of FIG. 1 and FIG. 3. Method 400 continues with step 402 leading from 306 of FIG. 3, where an outlet channel 1236 is led proximate to the molten material as it is deposited for a current layer on the substrate 1212 or on the metal article 200 to facilitate removal of any reactant gas 1224 present in the vicinity of the molten material. For example, the substrate 1212 may be a build plate. Method 400 continues from 402 to 102 of FIG.

[0025] In another example, the method 400 again includes the methods 100, 300 of FIG. 1 and FIG. 3. In this example, the method 400 continues from 306 of FIG. 3 to step 404 of applying a vacuum to the exit path 1236 of the build chamber 1202 to assist in purging the gaseous contents 1238 of the build chamber 1202. At 406, the vacuum on the exit path 1236 of the build chamber 1202 is stopped after a predetermined time based on the predicted completion of the purge. For example, the vacuum can be stopped by closing a valve at the exit port 1234, the vacuum pump 1242, or somewhere in between. The method 400 continues from 406 to 102 of FIG. 1. For example, the vacuum may be applied for various times to establish a suitable environment.

[0026] In yet another example, method 400 also includes methods 100, 300 of Figures 1 and 3. In this example, method 400 continues from 306 of Figure 3 and closes 408 the exit path 1236 from the build chamber 1202 after a predetermined time to seal the build chamber 1202 during the additive manufacturing process. Method 400 continues from 408 to 102 of Figure 1.

[0027] Referring again to Figures 1, 2, 5 and 12, in one or more examples, in another example of method 100, melting 104 of metal material 1208 includes step 502 of forming a molten pool as the molten material is deposited on the substrate 1212 or metal article 200 for the current layer.

[0028] In yet another example of method 100, at least one parameter of the molten pool is controlled to govern a chemical reaction that hardens at least one selected portion 204 of the plurality of selected layers 206 of the metal article 200. In a further example, the at least one parameter of the molten pool includes a metal pool size, a metal pool temperature, a transition time from molten material to solidification, or any other suitable parameter. The operation of the energy source and the control of the corresponding parameters can be based on the three-dimensional digital model 1232 of the metal article 200.

[0029] 1, 2, 6, and 12, in one or more examples, a method 600 for hardening a selected portion of a metal article 200 also includes the method 100 of FIG. 1. The method 600 continues from 104 of FIG. 1 to 602, where at least one inert gas 1220 is received from at least one first gas source 1222 and at least one reactive gas 1224 is received from at least one second gas source 1226. In 604, the at least one inert gas 1220 and the at least one reactive gas 1224 are delivered to the build chamber 1202 to establish a reactive atmosphere 1230. The method 600 continues from 604 to 106 of FIG.

[0030] In another example, the method 600 also includes a step 606 of directing at least one inert gas 1220 and at least one reactive gas 1224 to a location in the build chamber 1202 proximate to the molten material as it is deposited for a current layer on the substrate 1212 or on the metal article 200. For example, a dedicated nozzle or gas jet 1246 can be used to direct the at least one inert gas 1220 and at least one reactive gas 1224 to a location proximate to the molten material. In this example, the method 600 continues from 606 to 106 of FIG.

[0031] 1, 2, 6, 7, and 12, in one or more examples, a method 700 for hardening a selected portion of a metal article 200 includes methods 100, 600 of FIG. 1 and 6. Method 700 continues from 602 to 702 of FIG. 6 with mixing at least one inert gas 1220 from at least one first gas source 1222 and at least one reactive gas 1224 from at least one second gas source 1226 to form a predetermined reactive gas mixture 1227. At 704, the predetermined reactive gas mixture 1227 is delivered to the build chamber 1202 to establish a reactive atmosphere 1230. Method 700 continues from 704 to 106 of FIG.

[0032] In another example, the method 700 also includes a step 706 of directing the predetermined reactant gas mixture 1227 to a location in the build chamber 1202 proximate to the molten material as it is deposited for a current layer on the substrate 1212 or on the metal article 200. For example, a dedicated nozzle or gas jet 1246 may be used to direct the predetermined reactant gas mixture 1227 to a location proximate to the molten material. In this example, the method continues from 706 to 106 in FIG.

[0033] Referring again to Figures 1, 2, 4, 6, 8 and 12, in one or more examples, a method 800 for hardening a selected portion of a metal article 200 includes methods 100, 400, 600 of Figures 1, 4 and 6. Method 800 continues from 602 of Figure 6 to Figure 802, where in conjunction with sending at least one inert gas 1220 and at least one reactive gas 1224 to the build chamber 1202, an exit path 1236 is opened from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202. Method 800 continues from 802 to 106 of Figure 1. In another example of method 800, the exit path 1236 from the build chamber 1202 remains open during the additive manufacturing process to allow a continuous flow of at least one inert gas 1220 and at least one reactive gas 1224 to the build chamber 1202. In yet another example, the method 800 continues from 802 to 404 of FIG. 4 where a vacuum is applied to the outlet path 1236. Then, at 406, the vacuum is stopped. For example, the vacuum can be stopped by closing a valve at the outlet port 1234, the vacuum pump 1242, or anywhere in between. In this example, the method 800 continues from 406 to 106 of FIG. 1. In yet another example, the method 800 continues from 802 to 408 of FIG. 4 where the outlet path 1236 is closed. In this example, the method 800 continues from 408 to 106 of FIG. 1.

[0034] 1, 2, 4, 9, and 12, in one or more examples, a method 900 for hardening a selected portion of a metal article 200 includes methods 100, 400 of FIG. 1 and 4. Method 800 continues from 104 of FIG. 1 to 902, where at least one predetermined reactive gas mixture 1227 is received from at least one mixed gas source 1229. At 904, the at least one predetermined reactive gas mixture 1227 is delivered to the build chamber 1202 to establish a reactive atmosphere 1230. Method 900 continues from 904 to 106 of FIG.

[0035] In another example, the method 900 also includes a step 906 of directing at least one predetermined reactant gas mixture 1227 to a location in the build chamber 1202 proximate to the molten material as it is deposited for a current layer on the substrate 1212 or on the metal article 200. For example, a dedicated nozzle or gas jet 1246 may be used to direct the at least one predetermined reactant gas mixture 1227 to a location proximate to the molten material. In this example, the method 900 continues from 906 to 106 of FIG.

[0036] In another example, the method 900 also includes opening 908 an exit path 1236 from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with delivering the at least one predetermined reactant gas mixture 1227 to the build chamber 1202. In a further example, the exit path 1236 from the build chamber 1202 remains open during the additive manufacturing process to allow a continuous flow of the at least one inert gas 1220 and the at least one predetermined reactant gas mixture 1227 to one or more of the build chambers 1202. In another further example, the method 900 continues from 908 to 404 of FIG. 4 where a vacuum is applied to the exit path 1236. Then, at 406, the vacuum is stopped. For example, the vacuum can be stopped by closing a valve at the exit port 1234, the vacuum pump 1242, or anywhere in between. In this example, the method 900 continues from 406 to 106 of FIG. 1. In yet another further example, the method 900 continues from 908 where the exit path 1236 is closed to 408 of Figure 4. In this example, the method 900 continues from 408 to 106 of Figure 1.

[0037] 1, 2, 10 and 12, in one or more examples, a method 1000 for hardening selected portions of a metal article 200 includes the method 100 of FIG 1. The method 1000 continues from 106 to 1002 of FIG 1, performing a step 1002 of alternating between a step 102 of establishing a non-reactive atmosphere 1228 and a step 106 of selectively establishing a reactive atmosphere 1230 during a step 104 of melting a metal material 1208 to deposit a molten material that does not harden during a period of a non-reactive atmosphere 1228 and a step 106 of selectively establishing a reactive atmosphere 1230, such that the metal article 200 includes a first region where at least certain portions of the continuous layer are hardened and a second region where at least other portions of the continuous layer are not hardened. In other examples of method 100, alternating step 1002 may be accomplished by moving metal article 200 from a first system dedicated to additive manufacturing using a non-reactive atmosphere 1228 to a second system dedicated to additive manufacturing using a reactive atmosphere 1230. The transition between the first and second systems may be based on hardened and non-hardened regions defined in the design of metal article 200.

[0038] In another example of the method 1000, the melting 104 of the metal material 1208 to deposit the molten material in multiple layers 202 to build up the metal article 200, and the translational motion of the metal article 200 and / or the energy source 1216 are paused at selected locations where there are pre-defined transitions from a non-reactive atmosphere 1228 to a reactive atmosphere 1230 and vice versa. In a further example, the selected locations and pre-defined transitions are based on a three-dimensional digital model 1232 of the metal article 200 designated for hardening.

[0039] 1, 2, 11 and 12, in one or more examples, a method 1100 for hardening selected portions of a metal article 200 includes the method 100 of FIG 1. Method 1100 continues from 106 to 1102 of FIG 1 with heat treating 1102 the metal article 200 after completion of the additive manufacturing process to optimize hardening of the selected portions of the metal article hardened during the additive manufacturing process. At 1104, the metal article 200 is machined to produce a finish on the metal article 200.

[0040] With general reference to Figures 1, 2 and 12-19, by way of example, the present disclosure relates to an additive manufacturing system 1200 for hardening selected portions of a metal article 200. Figure 1 discloses an example of a method 100 for hardening selected portions of a metal article 200. Figure 2 discloses an example of a metal article 200. Figure 12 discloses various examples of the additive manufacturing system 1200. Figure 13 discloses various examples of a gas manifold assembly 1302 for the additive manufacturing system 1200. Figures 14-18 disclose various examples of configurations of the gas manifold assembly 1302. Figure 19 discloses various examples of a build chamber 1202 of the additive manufacturing system 1200.

[0041] 1, 2, and 12, in one or more examples, an additive manufacturing system 1200 for curing a selected portion of a metal article 200 includes a build chamber 1202, a material handling assembly 1206, a substrate 1212, an energy source assembly 1214, a translation assembly 1210, and a system control assembly 1218. The build chamber 1202 is configured to provide a controlled environment 1204 for additive manufacturing of the metal article 200. The material handling assembly 1206 is configured to supply a metal material 1208 to the interior of the build chamber 1202 in conjunction with the additive manufacturing process. The substrate 1212 is configured to at least temporarily hold the metal article 200 during the additive manufacturing process. For example, the substrate 1212 may be a build plate. The energy source assembly 1214 is configured to melt the metallic material 1208 using an energy source 1216 and deposit the molten material in multiple layers 202 to build the metallic article 200 on the substrate 1212. The translation assembly 1210 is configured to provide translational motion of at least one of the substrate 1212 and the energy source assembly 1214 based on predetermined locations for depositing the molten material in conjunction with an additive manufacturing process. A system control assembly 1218 is in operative communication with the material handling assembly 1206, the energy source assembly 1214, and the translation assembly 1210. The system control assembly 1218 is configured to control the establishment of a non-reactive atmosphere 1228 in the build chamber 1202, to control the supply of metal material 1208 by the material handling assembly 1206, to control the melting step 104 of the metal material 1208 by the energy source 1216 in conjunction with the control of the translation assembly 1210, and to control the selective establishment of a reactive atmosphere 1230 in the build chamber 1202 in conjunction with the melting step 104 and subsequent solidification of the molten material to chemically harden at least one selected portion 204 of each layer in the multiple selective layers 206 of the multiple layers 202.For example, a metal article having selected portions that are hardened may be constructed in its entirety using additive manufacturing, or an existing metal article produced using other techniques may have hardened material selectively added using additive manufacturing. In other examples, a vacuum may be applied first to establish the appropriate environment.

[0042] In another example of the additive manufacturing system 1200, the non-reactive atmosphere 1228 includes at least one inert gas 1220. In a further example, the at least one inert gas 1220 includes argon, helium, neon, nitrogen, or any other suitable inert gas in any suitable combination. For example, nitrogen can be used as a non-reactive gas or an inert gas for certain metallic materials. However, nitrogen may be a reactive gas for other metallic materials, such as titanium. In yet another example of the additive manufacturing system 1200, for an additive manufacturing process, the metallic material 1208 includes a metal powder, a metal wire, or any other suitable metallic material in any suitable combination. In yet another example of the additive manufacturing system 1200, the metallic material 1208 includes titanium, a titanium alloy, steel, a corrosion resistant steel, a precipitation hardened corrosion resistant steel, a maraging steel, an iron alloy, or any other suitable metallic material in any suitable combination. In yet another example of the additive manufacturing system 1200, the energy source 1216 includes at least one laser beam, at least one electron beam, at least one plasma arc, or any other suitable energy source in any suitable combination. In yet another example of the method 100, the energy source 1216 includes at least one laser beam, at least one electron beam, at least one plasma arc, or any other suitable energy source in any suitable combination.

[0043] In various examples, the depth of a given layer of the plurality of layers 202 deposited during an additive manufacturing process is between about 0.0001 inches and about 0.001 inches, between about 0.001 inches and about 0.002 inches, between about 0.002 inches and about 0.004 inches, between about 0.004 inches and about 0.010 inches, between about 0.010 inches and about 0.020 inches, or any other suitable depth range for an additive manufacturing process. The minimum depth of a given layer is based on the minimum deposition thickness. The deposited thickness may be based on at least one of the metallic material feedstock size and the energy provided to form the melt pool. For example, an additive manufacturing energy source may be used for "smoothing" and a reactive atmosphere may be used to deposit a very thin hardened layer on the metal article. In various other examples, the reactive atmosphere 1230 may include a mixture in which the reactive gas ranges from about 0.1% to about 50%, from about 0.2% to about 40%, from about 0.5% to about 30%, from about 0.8% to about 20%, from about 1.0% to about 10%, or any other suitable reactive gas percentage. For example, higher percentages for the mixture are contemplated if a higher reactive gas percentage (e.g., greater than 50%) is suitable for a given operation.

[0044] In another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to control at least one parameter of the energy source 1216 and the translation assembly 1210 to manage a chemical reaction that hardens at least one selected portion 204 of the plurality of selected layers 206 of the metal article 200. In a further example, the at least one parameter of the energy source 1216 and the translation assembly 1210 includes an energy source dwell time of a selected predetermined location for hardening at least one selected portion 204 of each layer in the plurality of selected layers 206 of the metal article 200, a laser deposition dwell time associated with the energy source 1216, a plasma arc dwell time associated with the energy source 1216, an electron beam dwell time associated with the energy source 1216, or any other suitable parameter in any suitable combination. The control of the translational motion, the operation of the energy source, and the corresponding parameters can be based on a three-dimensional digital model 1232 of the metal article 200.

[0045] In yet another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to control the translation assembly 1210 for linear motion of the metal article 200 in at least one of the X-axis, the Y-axis, and the Z-axis. In a further example, the system control assembly 1218 is configured to control the translation assembly 1210 for rotational motion of the metal article 200 relative to at least one of the X-axis, the Y-axis, and the Z-axis. In another further example, the system control assembly 1218 is configured to control the translation assembly 1210 for angular motion of the metal article 200 relative to at least one of the X-axis, the Y-axis, and the Z-axis. In yet another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to store or access a three-dimensional digital model 1232 of the metal article 200 that underlies the predetermined location for deposition of molten material.

[0046] In yet another example of the additive manufacturing system 1200, the reactive atmosphere 1230 includes a predetermined reactive gas mixture 1227 of at least one inert gas 1220 and at least one reactive gas 1224. In a further example, the chemical reaction includes nitridation. In a further example, the at least one reactive gas 1224 includes nitrogen gas, a nitrogen-based gas, ammonia gas, or any other suitable reactive gas in any suitable combination. In another further example, the chemical reaction includes carbonization. In a further example, the at least one reactive gas 1224 includes a carbon-based gas, acetylene gas, propane gas, butane gas, methane gas, carbon monoxide gas, or any other suitable reactive gas in any suitable combination. If the reactive gas or by-products of the chemical reaction produce hazardous gas mixtures, the process is managed by at least one of the use of vacuum, partial pressure, inert gas purging, and a gas safety control system.

[0047] In another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to store or access a three-dimensional digital model 1232 of the metal article 200 based on the corresponding location where each selected portion 204 of the metal article 200 to be hardened is designated for hardening. In yet another example of the additive manufacturing system 1200, at least one selected portion 204 of each layer of a plurality of selected layers 206 of the metal article 200 to be hardened includes one or more regions where portions of successive layers are to be hardened. In a further example, the portion of the continuous layer that is hardened includes at least one portion having a hardening depth in at least one of the following ranges: about 0.0001 inches deep through the metal article 200, about 0.002 inches deep through the metal article 200, about 0.004 inches deep through the metal article 200, about 0.006 inches deep through the metal article 200, about 0.008 inches deep through the metal article 200, about 0.010 inches deep through the metal article 200, about 0.020 inches deep through the metal article 200, about 0.030 inches deep through the metal article 200, about 0.040 inches deep through the metal article 200, or any other suitable hardening depth. In another further example, the one or more regions include at least one region of the interior of the metal article 200 that does not extend to an exterior surface of the metal article 200. As discussed above, the metal article 200 can be constructed with an intermittently hardened interior structure to meet any design requirements at the deposited layer level. For example, metal article 200 can include an interior region forming a metal matrix composite. In yet another further example, the one or more regions include at least one region extending from a first layer to a successive layer of metal article 200. In yet another further example, the one or more regions include at least one region extending from an interior layer of metal article 200 to an exterior surface of metal article 200 such that a portion of metal article 200 is case hardened. In a further example, the portion of metal article 200 that is case hardened includes at least one portion having a case hardening depth greater than about 0.0001 inches, about 0.001 inches, about 0.010 inches, about 0.020 inches, about 0.030 inches, about 0.040 inches, or any other suitable case hardening depth.

[0048] In yet another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to initiate the additive manufacturing process by selectively establishing 106 the reactive atmosphere 1230 prior to the step 102 of establishing the non-reactive atmosphere 1228. In yet another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to repeat the step 102 of establishing the non-reactive atmosphere 1228 and the step 106 of selectively establishing the reactive atmosphere 1230 during the step 104 of melting the metallic material 1208 to deposit molten material in multiple layers 202 until the metallic article 200 is completed.

[0049] 1, 2 and 12-19, in one or more examples of the additive manufacturing system 1200, the system control assembly 1218 includes a gas manifold assembly 1302. The gas manifold assembly 1302 includes at least one inert gas inlet 1304 and at least one inert gas outlet 1306. The at least one inert gas inlet 1304 is configured to receive at least one inert gas 1220 from at least one first gas source 1222 at a first inert gas inlet 1308. The gas manifold assembly 1302 is configured to direct the first inert gas inlet 1308 to a first inert gas outlet 1310. The gas manifold assembly 1302 is configured to supply the at least one inert gas 1220 to the build chamber 1202 via the first inert gas outlet 1310 to establish a non-reactive atmosphere 1228.

[0050] In another example of the additive manufacturing system 1200, the build chamber 1202 includes an outlet port 1234 configured to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with opening an outlet path 1236 from the build chamber 1202 and directing at least one inert gas 1220 to the build chamber 1202. In a further example, the build chamber 1202 also includes an exhaust conduit 1240 coupled to the outlet port 1234 and configured to direct the outlet path 1236 in proximity to the molten material as it is deposited for a current layer on the substrate 1212 or on the metal article 200 to facilitate removal of any reactant gas 1224 present in the vicinity of the molten material. For example, the substrate 1212 may be a build plate. In another further example, the gaseous contents 1238 purged from the build chamber 1202 include air, one or more reactant gases, one or more inert gases, or any other gases that may be present in the build chamber 1202 in any suitable combination. In yet another further example, the outlet port 1234 is configured to remain open during the additive manufacturing process such that the outlet path 1236 remains open to allow a continuous flow of the at least one inert gas 1220 into the build chamber 1202. In yet another further example, the additive manufacturing system 1200 also includes a vacuum pump 1242 coupled to the outlet port 1234 of the build chamber 1202 and configured to apply a vacuum to the outlet path 1236 to assist in purging the gaseous contents 1238 of the build chamber 1202. In yet another example, the vacuum pump 1242 is configured to stop the vacuum on the outlet path 1236 of the build chamber 1202 after a predetermined time based on a predicted completion of the purge. For example, the vacuum can be stopped by closing a valve at the outlet port 1234, the vacuum pump 1242, or somewhere in between. In yet another further example, the exit port 1234 is configured to close the exit path 1236 from the build chamber 1202 after a predetermined time to seal the build chamber 1202 during the additive manufacturing process.

[0051] In yet another example of the additive manufacturing system 1200, the gas manifold assembly 1302 also includes at least one reactant gas inlet 1312 and at least one reactant gas outlet 1314. The at least one reactant gas inlet 1312 is configured to receive at least one reactant gas 1224 from at least one second gas source 1226 at a first reactant gas inlet 1316. The gas manifold assembly 1302 is configured to direct the first reactant gas inlet 1316 to a first reactant gas outlet 1318. The gas manifold assembly 1302 is configured to deliver the at least one reactant gas 1224 to the build chamber 1202 via the first reactant gas outlet 1318 to establish the reactive atmosphere 1230. In a further example, the build chamber 1202 includes at least one supply conduit 1244 coupled to the first reactant gas outlet 1318 of the manifold assembly 1302. At least one supply conduit 1244 is configured to direct the at least one inert gas 1220 and the at least one reactant gas 1224 to a location within the build chamber 1202 proximate to the molten material as it is deposited for a current layer on the substrate 1212 or metal article 200. For example, a dedicated nozzle or gas jet 1246 can be used to direct the at least one inert gas 1220 and the at least one reactant gas 1224 to a location proximate to the molten material. In another further example, the build chamber 1202 includes an exit port 1234 configured to open an exit path 1236 from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with directing the at least one inert gas 1220 and the at least one reactant gas 1224 to the build chamber 1202. In a further example, the outlet port 1234 is configured to remain open during the additive manufacturing process such that the outlet path 1236 remains open to allow a continuous flow of at least one inert gas 1220 and at least one reactant gas 1224 into the build chamber 1202.

[0052] In yet another further example, the gas manifold assembly 1302 also includes at least one reactant gas inlet 1312 and at least one reactant gas mixture outlet 1320. The at least one inert gas inlet 1304 is configured to receive the at least one inert gas 1220 at a second inert gas inlet 1322. The at least one reactant gas inlet 1312 is configured to receive the at least one reactant gas 1224 at a second reactant gas inlet 1324. The gas manifold assembly 1302 is configured to mix the at least one inert gas 1220 received at the second inert gas inlet 1322 with the at least one reactant gas 1224 received at the second reactant gas inlet 1324 to form a predetermined reactant gas mixture 1227. The gas manifold assembly 1302 is configured to direct the predetermined reactant gas mixture 1227 to a first reactant gas mixture outlet 1326. The gas manifold assembly 1302 is configured to deliver the predetermined reactant gas mixture 1227 to the build chamber 1202 via the first reactant gas mixture outlet 1326 to establish the reactive atmosphere 1230. In a further example, the build chamber 1202 includes at least one supply conduit 1244 coupled to the first reactant gas mixture outlet 1326 of the manifold assembly 1302. The at least one supply conduit 1244 configured to direct the predetermined reactant gas mixture 1227 to a location in the build chamber 1202 proximate to the molten material as the molten material is deposited for a current layer on the substrate 1212 or on the metal article 200. For example, a dedicated nozzle or gas jet 1246 can be used to direct the predetermined reactant gas mixture 1227 to a location proximate to the molten material. In another further example, the build chamber 1202 includes an outlet port 1234 configured to open an outlet path 1236 from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with sending at least one inert gas 1220 and at least one reactive gas 1224 to the build chamber 1202.In a further example, the outlet port 1234 is configured to remain open during the additive manufacturing process such that the outlet path 1236 remains open to allow a continuous flow of at least one inert gas 1220 and at least one reactant gas 1224 into the build chamber 1202.

[0053] In yet another example of the additive manufacturing system 1200, the gas manifold assembly 1302 also includes at least one reactant gas mixture inlet 1328 and at least one reactant gas mixture outlet 1320. The at least one reactant gas mixture inlet 1328 is configured to receive the predetermined reactant gas mixture 1227 at the first reactant gas mixture inlet 1330. The gas manifold assembly 1302 is configured to direct the predetermined reactant gas mixture 1227 to the second reactant gas mixture outlet 1332. The gas manifold assembly 1302 is configured to deliver the predetermined reactant gas mixture 1227 to the build chamber 1202 via the second reactant gas mixture outlet 1332 to establish the reactive atmosphere 1230. In a further example, the build chamber 1202 includes at least one supply conduit 1244 coupled to the second reactant gas mixture outlet 1332 of the manifold assembly 1302. At least one supply conduit 1244 configured to direct at least one predetermined reactant gas mixture 1227 to a location in the build chamber 1202 proximate to the molten material as the molten material is deposited for a current layer on the substrate 1212 or metal article 200. For example, a dedicated nozzle or gas jet 1246 can be used to direct the at least one predetermined reactant gas mixture 1227 to a location proximate to the molten material. In another further example, the build chamber 1202 includes an exit port 1234 configured to open an exit path 1236 from the build chamber 1202 to purge the gaseous contents 1238 of the build chamber 1202 in conjunction with delivering the at least one predetermined reactant gas mixture 1227 to the build chamber 1202. In a further example, the outlet port 1234 is configured to remain open during the additive manufacturing process such that the outlet path 1236 remains open and allows continuous flow of at least one inert gas 1220 and at least one predetermined reactant gas mixture 1227 into one or more build chambers 1202.

[0054] 1, 2, and 12, in one or more examples, in another example of the additive manufacturing system 1200, the energy source 1216 is configured to cooperate with the melting 104 of the metal material 1208 to form a molten pool as the molten material is deposited for a current layer on the substrate 1212 or on the metal article 200. In a further example, the system control assembly 1218 is configured to control at least one parameter of the molten pool to manage a chemical reaction that hardens at least one selected portion 204 of the plurality of selected layers 206 of the metal article 200. In a further example, the at least one parameter of the molten pool includes a metal pool size, a metal pool temperature, a transition time from molten material to solidification, or any other suitable parameter. The control of the translational motion, the operation of the energy source, and the corresponding parameters can be based on a three-dimensional digital model 1232 of the metal article 200.

[0055] In yet another example of the additive manufacturing system 1200, the system control assembly 1218 is configured to alternate between the establishing 102 of the non-reactive atmosphere 1228 and the establishing 102 of the reactive atmosphere 1230 during the melting 104 of the metallic material 1208 to deposit molten material that does not harden during the non-reactive atmosphere 1228 and to deposit molten material that hardens during the reactive atmosphere 1230, such that the metallic article 200 includes a first region where at least certain portions of the successive layers harden and a second region where at least other portions of the successive layers do not harden. In a further example, the system control assembly 1218 is configured to pause the melting 104 of the metallic material 1208 to deposit molten material in a plurality of layers 202 to build the metallic article 200, and the translational motion provided by the translation assembly 1210 is provided at selected points where there is a predetermined transition from the non-reactive atmosphere 1228 to the reactive atmosphere 1230 and vice versa. In another further example, the system control assembly 1218 is configured to store or access a three-dimensional digital model 1232 of the metal article 200 based on the selected locations and corresponding locations where a pre-defined transition has been designated for hardening. In other examples, the additive manufacturing system 1200 may include a first system dedicated to additive manufacturing using a non-reactive atmosphere 1228 and a second system dedicated to additive manufacturing using a reactive atmosphere 1230. In these examples, alternating between hardened and non-hardened regions in the metal article 200 may be achieved by moving the metal article back and forth between the first and second systems based on the hardened and non-hardened regions defined in the design of the metal article 200.

[0056] 2 and 12, by way of example, the present disclosure is directed to a metal article 200. An example of a metal article 200 is disclosed in FIG 2. FIG 12 discloses various examples of an additive manufacturing system 1200 for hardening selected portions of the metal article 200.

[0057] 2 and 12 , in one or more examples, metal article 200 includes multiple layers 202 of metal material 1208 deposited via an additive manufacturing process. At least one selected portion 204 of each layer of multiple selected layers 206 of multiple layers 202 is hardened by a chemical reaction caused by a reactive atmosphere 1230 selectively established during a selected period of the additive manufacturing process. The remaining portions 208 of multiple selected layers 206 and the remaining layers 210 of multiple layers 202 were deposited during the remainder of the additive manufacturing process during which a non-reactive atmosphere 1228 was established.

[0058] In another example of the metal article 200, the non-reactive atmosphere 1228 includes at least one inert gas 1220. In yet another example of the metal article 200, for an additive manufacturing process, the metal material 1208 includes a metal powder, a metal wire, or any other suitable metal material in any suitable combination. In yet another example of the metal article 200, the metal material 1208 includes titanium, a titanium alloy, a steel, a corrosion resistant steel, a precipitation hardened corrosion resistant steel, a maraging steel, an iron alloy, or any other suitable metal material in any suitable combination. In yet another example of the method 100, the energy source 1216 includes at least one laser beam, at least one electron beam, at least one plasma arc, or any other suitable energy source in any suitable combination.

[0059] In various examples, the depth of a given layer of the plurality of layers 202 deposited during an additive manufacturing process is between about 0.0001 inches and about 0.001 inches, between about 0.001 inches and about 0.002 inches, between about 0.002 inches and about 0.004 inches, between about 0.004 inches and about 0.010 inches, between about 0.010 inches and about 0.020 inches, or any other suitable depth range for an additive manufacturing process. The minimum depth of a given layer is based on the minimum deposition thickness. The deposited thickness may be based on at least one of the metallic material feedstock size and the energy provided to form the melt pool. For example, an additive manufacturing energy source may be used for "smoothing" and a reactive atmosphere may be used to deposit a very thin hardened layer on the metal article. In various other examples, the reactive atmosphere 1230 may include a mixture in which the reactive gas ranges from about 0.1% to about 50%, from about 0.2% to about 40%, from about 0.5% to about 30%, from about 0.8% to about 20%, from about 1.0% to about 10%, or any other suitable reactive gas percentage. For example, higher percentages for the mixture are contemplated if a higher reactive gas percentage (e.g., greater than 50%) is suitable for a given operation.

[0060] In yet another example of the metal article 200, the reactive atmosphere 1230 includes a predetermined reactive gas mixture 1227 of at least one inert gas 1220 and at least one reactive gas 1224. In a further example, the at least one inert gas 1220 includes argon, helium, neon, nitrogen, or any other suitable inert gas in any suitable combination. For example, nitrogen can be used as a non-reactive gas or an inert gas for certain metallic materials. However, nitrogen may be a reactive gas for other metallic materials, such as titanium. In another further example, the chemical reaction includes nitridation. In a further example, the at least one reactive gas 1224 includes nitrogen gas, a nitrogen-based gas, ammonia gas, or any other suitable reactive gas in any suitable combination. In yet another further example, the chemical reaction includes carburization. In a further example, the at least one reactive gas 1224 includes a carbon-based gas, acetylene gas, propane gas, butane gas, methane gas, carbon monoxide gas, or any other suitable reactive gas in any suitable combination. If reactive gases or by-products of chemical reactions produce hazardous gas mixtures, the process is managed by at least one of the use of vacuum, partial pressure, inert gas purging, and gas safety control systems. In another example of the metal article 200, each selected portion 204 of the metal article 200 to be hardened is based on a corresponding location in a three-dimensional digital model 1232 of the metal article 200 designated for hardening. In yet another example of the method 100, the energy source 1216 includes at least one laser beam, at least one electron beam, at least one plasma arc, or any other suitable energy source in any suitable combination.

[0061] In yet another example of the metal article 200, the plurality of layers 202 of the metal article 200 are arranged in alternating groups of a plurality of selected layers 206 with cure and a plurality of remaining layers 210 without cure. In a further example, the at least one selected portion 204 of each layer of the plurality of selected layers 206 with cure is larger than other portions of the corresponding layer without cure. In another further example, the at least one selected portion 204 of each layer of the plurality of selected layers 206 with cure includes the corresponding layer and no portion of the corresponding layer is cured.

[0062] In yet another example of the metal article 200, the at least one selected portion 204 of each layer of the plurality of selected layers 206 of the metal article 200 to be hardened includes one or more regions where a portion of the continuous layer is hardened. In a further example, the portion of the continuous layer to be hardened includes at least one portion having a hardening depth in the range of about 0.0001 inches deep through the metal article 200, about 0.002 inches deep through the metal article 200, about 0.004 inches deep through the metal article 200, about 0.006 inches deep through the metal article 200, about 0.008 inches deep through the metal article 200, about 0.010 inches deep through the metal article 200, about 0.020 inches deep through the metal article 200, about 0.030 inches deep through the metal article 200, about 0.040 inches deep through the metal article 200, or any other suitable range of hardening depths. In another further example, the one or more regions include at least one region of the interior of the metal article 200 that does not extend to the exterior surface of the metal article 200. As discussed above, the metal article 200 can be constructed with an intermittently hardened internal structure to meet any design requirements at the deposition layer level. For example, the metal article 200 can include an internal region that forms a metal matrix composite. In yet another further example, the one or more regions include at least one region that extends from a first layer to a successive layer of the metal article 200. In yet another further example, the one or more regions include at least one region that extends from an interior layer of the metal article 200 to the exterior surface of the metal article 200 such that a portion of the metal article 200 is case hardened. In a further example, the portion of the metal article 200 that is case hardened includes at least one portion having a case hardening depth that is greater than about 0.0001 inches, about 0.001 inches, about 0.010 inches, about 0.020 inches, about 0.030 inches, about 0.040 inches, or any other suitable case hardening depth.

[0063] In yet another example of a metal article 200, step 102 of establishing a non-reactive atmosphere 1228 and step 106 of selectively establishing a reactive atmosphere 1230 are repeated in conjunction with an additive manufacturing process, such that certain portions of the metal article 200 constructed during the reactive atmosphere 1230 are hardened and other portions constructed during the non-reactive atmosphere 1228 are not hardened, such that the metal article 200 includes a first region where at least certain portions of the successive layer are hardened and a second region where at least other portions of the successive layer are not hardened.

[0064] The examples of metal article 200 and additive manufacturing system 1200 for hardening selected portions of metal article 200 may be related to or used in the context of aircraft manufacturing. Although an aircraft example is described, the examples and principles disclosed herein may be applied to other products in the aerospace industry, and other industries, such as the automotive industry, the space industry, the construction industry, and other design and manufacturing industries. Thus, in addition to aircraft, the examples and principles disclosed herein may be applied to the use of metal articles in the manufacture of various types of vehicles and the construction of various types of buildings.

[0065] The foregoing detailed description refers to the accompanying drawings, which show specific examples described by the present disclosure. Other examples having different structures and operations do not depart from the scope of the present disclosure. Similar reference numbers may refer to the same features, elements, or components in different drawings. Throughout this disclosure, any of a plurality of items may be referred to individually, and a plurality of items may be referred to collectively and may be referred to by similar reference numbers. Furthermore, as used herein, a feature, element, component, or step preceding the word "a" or "an" should be understood as not excluding a plurality of features, elements, components, or steps, unless such exclusion is expressly stated.

[0066] Illustrative, non-exhaustive examples of the subject matter according to the present disclosure are provided above, although not necessarily claimed. Reference herein to an "example" means that one or more of the features, structures, elements, components, characteristics, and / or operational steps described in connection with the example are included in at least one aspect, embodiment, and / or implementation of the subject matter according to the present disclosure. Thus, throughout this disclosure, the phrases "one example," "another example," "one or more examples," and similar language can, but do not necessarily, refer to the same example. Furthermore, subject matter characterizing any one example can, but does not necessarily, include subject matter characterizing any other example. Also, subject matter characterizing any one example can, but does not necessarily, be combined with subject matter characterizing any other example.

[0067] As used herein, a system, apparatus, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is actually capable of performing the specified function without modification, rather than merely having the potential to perform the specified function after further modification. In other words, a system, apparatus, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function. As used herein, "configured to" refers to an existing characteristic of a system, apparatus, structure, article, element, component, or hardware that enables the system, apparatus, structure, article, element, component, or hardware to perform a specified function without further modification. For purposes of this disclosure, a system, apparatus, device, structure, article, element, component, or hardware that is described as "configured to" perform a particular function may additionally or alternatively be described as "adapted to" and / or "operating to" perform that function.

[0068] Unless otherwise specified, the terms "first," "second," "third," etc. are used merely as labels and are not intended to impose any order, arrangement, or hierarchy requirements on the items to which these terms refer. Further, a reference to, for example, a "second" item does not require or exclude the presence of, for example, a "first" or lower-numbered item, and / or, for example, a "third" or higher-numbered item.

[0069] As used herein, the phrase "at least one of," when used in conjunction with a list of items, means that various combinations of one or more of the listed items may be used and only one of each item in the list may be required. For example, "at least one of item A, item B, and item C" may include, without limitation, item A, or item A and item B. This example may also include item A, item B, and item C, or item B and item C. In other examples, "at least one of" may be, without limitation, two of item A, one of item B, and ten of item C, or four of item B and seven of item C, or other suitable combinations. As used herein, the term "and / or" and the " / " symbol include any and all combinations of one or more of the associated listed items.

[0070] As used herein, the terms "coupled," "couple," and similar terms refer to two or more elements that are joined, coupled, secured, attached, connected, in communication, or associated with one another (e.g., mechanically, electrically, fluidly, optically, electromagnetically). In various examples, the elements may be directly or indirectly associated. As an example, element A may be directly associated with element B. As another example, element A may be indirectly associated with element B, e.g., through another element C. It will be understood that not all relationships between the various disclosed elements are necessarily depicted. Thus, other connections than those shown in the figures may exist.

[0071] As used herein, the term "approximately" refers to or describes a condition that is close to, but not exactly, the described condition that still performs the desired function or achieves the desired result. As an example, the term "approximately" refers to a condition that is within an acceptable predetermined tolerance or precision, such as a condition within 10% of the described condition. However, the term "approximately" does not exclude a condition that is exactly the described condition. As used herein, the term "substantially" refers to a condition that performs the desired function or achieves the desired result essentially as described.

[0072] In the above-mentioned FIG. 1 and FIG. 3-FIG. 11, the blocks may represent operations, steps, and / or portions thereof, and the lines connecting various blocks do not imply a particular order or dependency of the operations or portions thereof. It will be understood that not all dependencies between various disclosed operations are necessarily represented. FIG. 1 and FIG. 3-FIG. 11 and the accompanying disclosure describing the operations of the method described herein should not be construed as necessarily dictating the sequence in which the operations are performed. Rather, while one exemplary order is shown, it should be understood that the sequence of the operations may be modified where appropriate. Thus, modifications, additions, and / or omissions may be made to the illustrated operations, and certain operations may be performed in a different order or simultaneously. In addition, those skilled in the art will understand that not all operations described necessarily need to be performed.

[0073] 2 and 12-19 referenced above may represent functional elements, forms, or components thereof, and do not necessarily imply a specific structure. Thus, modifications, additions, and / or omissions may be made to the illustrated structures. In addition, those skilled in the art will understand that not all elements, forms, and / or components described and illustrated in the above-mentioned FIGS. 2 and 12-19 need to be included in every example, and not all elements, forms, and / or components described herein are necessarily shown in each illustrative example. Thus, some of the elements, forms, and / or components described and illustrated in FIGS. 2 and 12-19 may be combined in various ways without necessarily including other forms described and illustrated in FIGS. 2 and 12-19 and / or the accompanying disclosure, even if such combination or combinations are not explicitly shown herein. Similarly, additional forms, not limited to the examples presented, may be combined with some or all of the forms shown and described herein. Unless otherwise indicated, the schematic diagrams of the examples shown in FIG. 2 and FIG. 12-FIG. 19 above do not imply structural limitations on the illustrative examples. Rather, one exemplary structure is shown, but it should be understood that the structure may be modified where appropriate. Thus, modifications, additions, and / or omissions may be made to the illustrated structure. Furthermore, elements, features, and / or components that serve similar or at least substantially similar purposes may be labeled with similar numbers in each of FIG. 2 and FIG. 12-FIG. 19, and such elements, features, and / or components may not be described in detail herein with reference to each of FIG. 2 and FIG. 12-FIG. 19. Similarly, not all elements, features, and / or components are labeled in each of FIG. 2 and FIG. 12-FIG. 19, and reference numbers associated therewith may be utilized herein for consistency.

[0074] Furthermore, throughout this specification, references to features, advantages, or similar language used herein do not imply that all features and advantages that may be realized in the examples disclosed herein should be or are in any single example. Rather, language referring to features and advantages is understood to mean that the particular feature, advantage, or characteristic described in connection with the example is included in at least one example. Thus, descriptions of features, advantages, and similar language used throughout this disclosure may, but do not necessarily, refer to the same example.

[0075] Examples of the subject matter disclosed herein may be described in the context of an aircraft manufacturing and maintenance service method 2000 shown in FIG. 20 and an aircraft 2100 shown in FIG. 21. In one or more examples, the disclosed methods and systems for relating test data of a part under test to an end item coordinate system may be used in aircraft manufacturing. Prior to production, the maintenance service method 2000 may include specification and design (block 2002) and material procurement (block 2004) of the aircraft 2100. During production, manufacturing (block 2006) and system integration (block 2008) of components and subassemblies of the aircraft 2100 may occur. Thereafter, the aircraft 2100 may undergo certification and delivery (block 2010) and be placed in service (block 2012). In service, the aircraft 2100 may be scheduled for routine maintenance and service (block 2014). Routine maintenance and service may include modification, reconfiguration, refurbishment, etc. of one or more systems of the aircraft 2100.

[0076] Each of the processes of maintenance method 2000 may be performed or carried out by a system integrator, a third party, and / or an operator (e.g., a customer). As used herein, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors, a third party may include, but is not limited to, any number of vendors, subcontractors, and suppliers, and an operator may be an airline, a leasing company, a military agency, a service organization, etc.

[0077] As shown in FIG. 21 , an aircraft 2100 produced by the maintenance method 2000 can include an airframe 2102 having a number of higher-level systems 2104 and an interior 2106. Examples of higher-level systems 2104 include one or more of a propulsion system 2108, an electrical system 2110, a hydraulic system 2112, and an environmental system 2114. Any number of other systems may be included. Although an aerospace example is shown, the principles disclosed herein may be applied to other industries, such as the automotive industry. Thus, in addition to the aircraft 2100, the principles disclosed herein may be applied to other vehicles, such as land vehicles, sea vehicles, space vehicles, and the like.

[0078] The disclosed systems and methods for relating test data of a part under test to an end item coordinate system may be used during any one or more stages of manufacturing and maintenance method 2000. For example, components or subassemblies corresponding to manufacturing of components and subassemblies (block 2006) may be fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft 2100 is in service (block 2012). Also, one or more examples of the system, method, or combinations thereof may be utilized during the production stage (blocks 2006 and 2008), for example, by substantially facilitating assembly or reducing costs of aircraft 2100. Similarly, one or more examples of implementations of the system or method or combinations thereof may be utilized while aircraft 2100 is in service (block 2012) and / or during maintenance and service (block 2014), by way of example and not limitation.

[0079] The described features, advantages, and characteristics of one example may be combined in any suitable manner in one or more other examples. Those skilled in the relevant art will recognize that the examples described herein may be practiced without one or more specific features or advantages of a particular example. In other examples, additional features and advantages may be recognized in a particular example that may not be present in all examples. Furthermore, while various examples of methods 100, 300, 400, 600, 700, 800, 900, 1000, 1100 for hardening a selected portion of a metal article, additive manufacturing systems 1200 for hardening a selected portion of a metal article, and metal articles 200 have been shown and described, modifications will occur to those skilled in the art upon reading this specification. The present application includes such modifications and is limited only by the scope of the claims. The subject matter of the present invention is also provided by the following paragraphs. [Section 1] A method (100) for hardening a selected portion of a metal article (200), the method (100) comprising: Establishing (102) a non-reactive atmosphere (1228) in a build chamber (1202) of an additive manufacturing system (1200); melting (104) a metal material (1208) using the energy source (1216) to deposit the molten material in a plurality of layers (202) to build up the metal article (200) in conjunction with controlling translational motion of at least one of the metal article (200) and an energy source (1216) based on predetermined locations for depositing the molten material; selectively establishing (106) a reactive atmosphere (1230) within the build chamber (1202) that induces a chemical reaction in conjunction with the melting (104) and subsequent solidification of the molten material to harden at least one selected portion (204) of each layer within a plurality of selected layers (206) of the plurality of layers (202); A method (100) comprising: [Section 2] Item 10. The method of item 1, wherein the non-reactive atmosphere (1228) comprises at least one inert gas (1220). [Section 3] 3. The method of claim 2, wherein the at least one inert gas (1220) comprises at least one of argon, helium, neon, and nitrogen. [Section 4] Item 10. The method of item 1, wherein in connection with the additive manufacturing process, the metal material (1208) comprises at least one of a metal powder and a metal wire. [Section 5] Item 10. The method of item 1, wherein the metallic material (1208) comprises at least one of titanium, a titanium alloy, steel, a corrosion resistant steel, a precipitation hardened corrosion resistant steel, a maraging steel, and a steel alloy. [Section 6] Item 10. The method of item 1, wherein the energy source (1216) comprises one or more of at least one laser beam, at least one electron beam, and at least one plasma arc. [Section 7] Item 1. The method of item 1, wherein at least one parameter of the translational motion of the metal article (200), the translational motion of the energy source (1216), and the operation of the energy source (1216) are controlled to manage the chemical reaction that hardens the at least one selected portion (204) of the plurality of selected layers (206) of the metal article (200). [Section 8] 8. The method of claim 7, wherein the at least one parameter of the energy source (1216) and the translational motion of the metal article (200) and / or the energy source (1216) comprises at least one of an energy source dwell time for selecting a predetermined location for hardening the at least one selected portion (204) of each layer in the plurality of selective layers (206) of the metal article (200), a laser deposition dwell time associated with the energy source (1216), a plasma arc dwell time associated with the energy source (1216), and an electron beam dwell time associated with the energy source (1216). [Section 9] Item 14. The method of item 1, wherein the translational motion of the metal article (200) and / or the energy source (1216) includes control of linear motion in at least one of an X-axis, a Y-axis, and a Z-axis. [Section 10] 10. The method of claim 9, wherein the translational movement of the metal article (200) and / or the energy source (1216) includes control of rotational movement about at least one of the X-axis, the Y-axis, and the Z-axis. [Section 11] 10. The method of claim 9, wherein the translational motion of the metal article (200) and / or the energy source (1216) includes control of angular motion relative to at least one of the X-axis, the Y-axis, and the Z-axis. [Section 12] Item 10. The method of item 1, wherein the predetermined location for deposition of the molten material is based on a three-dimensional digital model (1232) of the metal article (200). [Section 13] Item 11. The method of item 1, wherein the reactive atmosphere (1230) comprises a predetermined reactive gas mixture (1227) of at least one inert gas (1220) and at least one reactive gas (1224). [Section 14] Item 14. The method of item 13, wherein the chemical reaction comprises nitridation. [Section 15] Item 15. The method of item 14, wherein the at least one reactant gas (1224) comprises at least one of nitrogen gas, a nitrogen-based gas, and ammonia gas. [Section 16] 14. The method of claim 13, wherein the chemical reaction comprises carbonization. [Section 17] 20. The method of claim 16, wherein the at least one reactant gas (1224) comprises at least one of a carbon-based gas, an acetylene gas, a propane gas, a butane gas, a methane gas, and a carbon monoxide gas. [Section 18] Item 10. The method of item 1, wherein each selected portion (204) of the metal article (200) to be hardened is based on a corresponding location within a three-dimensional digital model (1232) of the metal article (200) designated for hardening. [Section 19] Item 10. The method of item 1, wherein the at least one selected portion (204) of each layer of a plurality of selected layers (206) of the metal article (200) to be hardened includes one or more regions where portions of a continuous layer are hardened. [Section 20] 20. The method of claim 19, wherein the portion of the continuous layer being hardened includes at least one portion having a hardening depth ranging from at least one of 0.0001 inch, 0.002 inch, 0.004 inch, 0.006 inch, 0.008 inch, 0.010 inch, 0.020 inch, 0.030 inch, and 0.040 inch to a depth through the metal article (200). [Section 21] 20. The method of claim 19, wherein the one or more regions include at least one region within the metal article (200) that does not extend to an exterior surface of the metal article (200). [Section 22] 20. The method of claim 19, wherein the one or more regions include at least one region extending from a first layer to a successive layer of the metal article (200). [Section 23] 20. The method of claim 19, wherein the one or more regions include at least one region extending from an interior layer of the metal article (200) to an exterior surface of the metal article (200) such that a portion of the metal article (200) is case hardened. [Section 24] 24. The method of claim 23, wherein the case hardened portion of the metal article (200) includes at least one portion having a case hardening depth greater than at least one of 0.0001 inches, 0.001 inches, 0.010 inches, 0.020 inches, 0.030 inches, and 0.040 inches. [Section 25] 2. The method of claim 1, wherein the step (106) of selectively establishing the reactive atmosphere (1230) precedes the step (102) of establishing the non-reactive atmosphere (1228). [Section 26] 2. The method of claim 1, wherein the step (102) of establishing the non-reactive atmosphere (1228) and the step (106) of selectively establishing the reactive atmosphere (1230) are repeated during the step (104) of melting the metal material (1208) to deposit molten material in the plurality of layers (202) until the metal article (200) is completed. [Section 27] Receiving (302) at least one inert gas (1220) from at least one first gas source (1222); delivering (304) the at least one inert gas (1220) to the build chamber (1202) to establish the non-reactive atmosphere (1228); The method of claim 1, further comprising: [Section 28] In conjunction with the step of delivering at least one inert gas (1220) to the build chamber (1202), opening (306) an exit path (1236) from the build chamber (1202) to purge the gaseous contents (1238) of the build chamber (1202). 28. The method of claim 27, further comprising: [Section 29] 29. The method of claim 28, wherein the gaseous contents (1238) purged from the build chamber (1202) include at least one of air, one or more reactive gases, and one or more inert gases. [Section 30] 29. The method of claim 28, wherein the exit path (1236) from the build chamber (1202) remains open during the additive manufacturing process, allowing a continuous flow of the at least one inert gas (1220) into the build chamber (1202). [Section 31] directing (402) the outlet path (1236) in close proximity to the molten material to facilitate removal of any reactant gas (1224) present in the vicinity of the molten material as the molten material is deposited for a current layer on a substrate (1212) or on the metal article (200). 29. The method of claim 28, further comprising: [Section 32] applying (404) a vacuum to the exit passage (1236) of the build chamber (1202) to assist in purging the gaseous contents (1238) of the build chamber (1202); 29. The method of claim 28, further comprising: [Section 33] Turning off the vacuum (406) on the exit path (1236) of the build chamber (1202) after a predetermined time based on the predicted completion of the purge. 33. The method of claim 32, further comprising: [Section 34] Closing (408) the exit path (1236) from the build chamber (1202) after a predetermined time to seal the build chamber (1202) during the additive manufacturing process. 29. The method of claim 28, further comprising: [Section 35] The step (104) of melting the metallic material (1208) comprises: forming a molten pool (502) as the molten material is deposited on a substrate (1212) or on the metal article (200) for a current layer; The method according to item 1, comprising: [Section 36] 36. The method of claim 35, wherein at least one parameter of the molten pool is controlled to manage the chemical reaction that hardens the at least one selected portion (204) of the plurality of selected layers (206) of the metal article (200). [Section 37] 37. The method of claim 36, wherein the at least one parameter of the molten pool includes at least one of a metal pool size, a metal pool temperature, and a transition time from molten material to solidification. [Section 38] receiving (602) at least one inert gas (1220) from at least one first gas source (1222) and at least one reactive gas (1224) from at least one second gas source (1226); delivering (604) the at least one inert gas (1220) and the at least one reactive gas (1224) to the build chamber (1202) to establish the reactive atmosphere (1230); The method of claim 1, further comprising: [Section 39] directing (606) the at least one inert gas (1220) and the at least one reactive gas (1224) to a location in the build chamber (1202) proximate to the molten material as it is being deposited for a current layer on the substrate (1212) or on the metal article (200); 39. The method of claim 38, further comprising: [Section 40] mixing (702) the at least one inert gas (1220) from the at least one first gas source (1222) and the at least one reactant gas (1224) from the at least one second gas source (1226) to form a predetermined reactant gas mixture (1227); delivering (704) the predetermined reactive gas mixture (1227) to the build chamber (1202) to establish the reactive atmosphere (1230); 39. The method of claim 38, further comprising: [Section 41] directing (706) the predetermined reactive gas mixture (1227) to a location within the build chamber (1202) proximate to the molten material as it is being deposited for a current layer on a substrate (1212) or on the metal article (200); 41. The method of claim 40, further comprising: [Section 42] In conjunction with delivering the at least one inert gas (1220) and the at least one reactive gas (1224) to the build chamber (1202), opening (802) an exit path (1236) from the build chamber (1202) to purge the gaseous contents (1238) of the build chamber (1202). 39. The method of claim 38, further comprising: [Section 43] 43. The method of claim 42, wherein the exit path (1236) from the build chamber (1202) remains open during the additive manufacturing process, allowing a continuous flow of the at least one inert gas (1220) and the at least one reactive gas (1224) into the build chamber (1202). [Section 44] Receiving (902) at least one predetermined reactant gas mixture (1227) from at least one mixed gas source (1229); delivering (904) the at least one predetermined reactive gas mixture (1227) to the build chamber (1202) to establish the reactive atmosphere (1230); The method of claim 1, further comprising: [Section 45] directing (906) the at least one predetermined reactive gas mixture (1227) to a location in the build chamber (1202) proximate to the molten material as it is being deposited on the substrate (1212) or for a current layer on the metal article (200); 45. The method of claim 44, further comprising: [Section 46] In conjunction with the step of delivering the at least one predetermined reaction gas mixture (1227) to the build chamber (1202), opening (908) an exit path (1236) from the build chamber (1202) to purge the gaseous contents (1238) of the build chamber (1202). 45. The method of claim 44, further comprising: [Section 47] 47. The method of claim 46, wherein the exit path (1236) from the build chamber (1202) remains open during the additive manufacturing process to allow a continuous flow of the at least one inert gas (1220) and the at least one predetermined reaction gas mixture (1227) into one or more of the build chambers (1202). [Section 48] a step (1002) of alternating between the step (102) of establishing the non-reactive atmosphere (1228) and the step (106) of selectively establishing the reactive atmosphere (1230) during the step (104) of melting the metallic material (1208) to deposit a molten material that does not harden during the non-reactive atmosphere (1228) and to deposit a molten material that hardens during the reactive atmosphere (1230), such that the metallic article (200) includes a first region in which at least certain portions of the continuous layer harden and a second region in which at least other portions of the continuous layer do not harden. The method of claim 1, further comprising: [Section 49] 49. The method of claim 48, wherein the step (104) of melting the metal material (1208) for depositing molten material into the plurality of layers (202) to build up the metal article (200), and the translational motion of the metal article (200) and / or the energy source (1216) are paused at selected points where there is a predetermined transition from the non-reactive atmosphere (1228) to the reactive atmosphere (1230) and vice versa. [Section 50] 50. The method of claim 49, wherein the selected locations and the predetermined transitions are based on a three-dimensional digital model (1232) of the metal article (200) designated for hardening. [Section 51] heat treating (1102) the metal article (200) after completion of the additive manufacturing process to optimize hardening of the selected portions of the metal article hardened during the additive manufacturing process; machining (1104) the metal article (200) to create a finish on the metal article (200); The method of claim 1, further comprising: [Section 52] 1. An additive manufacturing system (1200) for hardening a selected portion of a metal article (200), the additive manufacturing system comprising: a build chamber (1202) that provides a controlled environment (1204) for additive manufacturing of the metal article (200); a material handling assembly (1206) for delivering a metal material (1208) into the build chamber (1202) in conjunction with an additive manufacturing process; a substrate (1212) for at least temporarily supporting the metal article (200) during the additive manufacturing process; an energy source assembly (1214) for melting the metallic material (1208) using an energy source (1216) and depositing the molten material in a plurality of layers (202) to build the metallic article (200) on the substrate (1212); a translation assembly (1210) for providing translational motion of at least one of the substrate (1212) and the energy source assembly (1214) based on predetermined locations for depositing the molten material in conjunction with the additive manufacturing process; a system control assembly (1218) in operative communication with the material handling assembly (1206), the energy source assembly (1214), and the translating assembly (1210), the system control assembly (1218) controlling the establishment of a non-reactive atmosphere (1228) in the build chamber (1202), controlling the supply of the metallic material (1208) by the material handling assembly (1206), controlling the melting (104) of the metallic material (1208) by the energy source (1216) in conjunction with controlling the translating assembly (1210), and controlling the selective establishment of a reactive atmosphere (1230) in the build chamber (1202) to effect a chemical reaction and harden at least one selected portion (204) of each layer in a plurality of selected layers (206) of the plurality of layers (202) in conjunction with the melting (104) and subsequent solidification of the molten material; An additive manufacturing system (1200). [Section 53] 53. The additive manufacturing system of claim 52, wherein the non-reactive atmosphere (1228) comprises at least one inert gas (1220). [Section 54] 54. The additive manufacturing system of claim 53, wherein the at least one inert gas (1220) comprises at least one of argon, helium, neon, and nitrogen. [Section 55] Item 53. The additive manufacturing system of item 52, in connection with the additive manufacturing process, wherein the metal material (1208) comprises at least one of a metal powder and a metal wire. [Section 56] 53. The additive manufacturing system of claim 52, wherein the metal material (1208) comprises at least one of titanium, a titanium alloy, steel, corrosion resistant steel, precipitation hardened corrosion resistant steel, maraging steel, and a steel alloy. [Section 57] 53. The additive manufacturing system of claim 52, wherein the energy source (1216) includes one or more of at least one laser beam, at least one electron beam, and at least one plasma arc. [Section 58] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) is configured to control at least one parameter of the energy source (1216) and the translation assembly (1210) to manage the chemical reaction that hardens the at least one selected portion (204) of the plurality of selected layers (206) of the metal article (200). [Section 59] 59. The additive manufacturing system of claim 58, wherein the at least one parameter of the energy source (1216) and the translation assembly (1210) includes at least one of an energy source dwell time of a selected predetermined location for hardening the at least one selected portion (204) of each layer in the plurality of selected layers (206) of the metal article (200), a laser deposition dwell time associated with the energy source (1216), a plasma arc dwell time associated with the energy source (1216), and an electron beam dwell time associated with the energy source (1216). [Section 60] Item 53. The additive manufacturing system of item 52, wherein the system control assembly (1218) is configured to control the translation assembly (1210) with respect to linear motion of the metal article (200) in at least one of the X-axis, Y-axis, and Z-axis. [Section 61] Item 61. The additive manufacturing system of item 60, wherein the system control assembly (1218) is configured to control the translation assembly (1210) with respect to rotational movement of the metal article (200) relative to at least one of the X-axis, the Y-axis, and the Z-axis. [Section 62] Item 61. The additive manufacturing system of item 60, wherein the system control assembly (1218) is configured to control the translation assembly (1210) with respect to angular motion of the metal article (200) relative to at least one of the X-axis, the Y-axis, and the Z-axis. [Section 63] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) is configured to store or access a three-dimensional digital model (1232) of the metal article (200) on which the predetermined location for deposition of the molten material is based. [Section 64] 53. The additive manufacturing system of claim 52, wherein the reactive atmosphere (1230) comprises a predetermined reactive gas mixture (1227) of at least one inert gas (1220) and at least one reactive gas (1224). [Section 65] Item 65. The additive manufacturing system of item 64, wherein the chemical reaction includes nitridation. [Section 66] Item 66. The additive manufacturing system of item 65, wherein the at least one reactive gas (1224) comprises at least one of nitrogen gas, a nitrogen-based gas, and ammonia gas. [Section 67] Item 65. The additive manufacturing system of item 64, wherein the chemical reaction includes carbonization. [Section 68] Item 68. The additive manufacturing system of item 67, wherein the at least one reactive gas (1224) comprises at least one of a carbon-based gas, an acetylene gas, a propane gas, a butane gas, a methane gas, and a carbon monoxide gas. [Section 69] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) is configured to store or access a three-dimensional digital model (1232) of the metal article (200), and each selected portion (204) of the metal article (200) to be hardened is based on a corresponding location designated for hardening. [Section 70] 53. The additive manufacturing system of claim 52, wherein the at least one selected portion (204) of each of a plurality of selected layers (206) of the metal article (200) to be hardened includes one or more areas where portions of successive layers are hardened. [Section 71] 71. The additive manufacturing system of claim 70, wherein the portion of the successive layer being hardened includes at least one portion having a hardening depth ranging from at least one of 0.0001 inches, 0.002 inches, 0.004 inches, 0.006 inches, 0.008 inches, 0.010 inches, 0.020 inches, 0.030 inches, and 0.040 inches to a depth through the metal article (200). [Section 72] 71. The additive manufacturing system of claim 70, wherein the one or more regions include at least one region within the metal article (200) that does not extend to an outer surface of the metal article (200). [Section 73] 71. The additive manufacturing system of claim 70, wherein the one or more regions include at least one region extending from a first layer to successive layers of the metal article (200). [Section 74] 71. The additive manufacturing system of claim 70, wherein the one or more regions include at least one region extending from an inner layer of the metal article (200) to an outer surface of the metal article (200) such that a portion of the metal article (200) is surface hardened. [Section 75] 75. The additive manufacturing system of claim 74, wherein the surface hardened portion of the metal article (200) includes at least one portion having a surface hardened depth greater than at least one of 0.0001 inches, 0.001 inches, 0.010 inches, 0.020 inches, 0.030 inches, and 0.040 inches. [Section 76] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) is configured to initiate the additive manufacturing process by selectively establishing (106) the reactive atmosphere (1230) prior to establishing (102) the non-reactive atmosphere (1228). [Section 77] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) is configured to repeat the step (102) of establishing the non-reactive atmosphere (1228) and the step (106) of selectively establishing the reactive atmosphere (1230) during the step (104) of melting the metal material (1208) to deposit molten material in the plurality of layers (202) until the metal article (200) is completed. [Section 78] said system control assembly (1218) a gas manifold assembly (1302) including at least one inert gas inlet (1304) and at least one inert gas outlet (1306), the at least one inert gas inlet (1304) receiving the at least one inert gas (1220) from the at least one first gas source (1222) at a first inert gas inlet (1308), the gas manifold assembly (1302) directing the first inert gas inlet (1308) to a first inert gas outlet (1310), the gas manifold assembly (1302) supplying the at least one inert gas (1220) to the build chamber (1202) via the first inert gas outlet (1310) to establish the non-reactive atmosphere (1228); Item 53. An additive manufacturing system according to item 52, comprising: [Section 79] The build chamber (1202) an outlet port (1234) that opens an outlet path (1236) from said build chamber (1202) to purge the gaseous contents (1238) of said build chamber (1202) in conjunction with said step of delivering said at least one inert gas (1220) to said build chamber (1202); Item 79. The additive manufacturing system of item 78, comprising: [Section 80] The build chamber (1202) an exhaust conduit (1240) coupled to the outlet port (1234) and directing the outlet path (1236) in close proximity to the molten material as the molten material is being deposited for a current layer on the substrate (1212) or on the metal article (200) to facilitate removal of any reactant gas (1224) present in the vicinity of the molten material; Item 80. The additive manufacturing system of item 79, further comprising: [Section 81] 80. The additive manufacturing system of claim 79, wherein the gaseous contents (1238) purged from the build chamber (1202) include at least one of air, one or more reactive gases, and one or more inert gases. [Section 82] 80. The additive manufacturing system of claim 79, wherein the outlet port (1234) is configured to remain open during the additive manufacturing process such that the outlet path (1236) remains open and allows continuous flow of the at least one inert gas (1220) into the build chamber (1202). [Section 83] a vacuum pump (1242) coupled to the outlet port (1234) of the build chamber (1202) and configured to apply a vacuum to the outlet passage (1236) to assist in purging the gaseous contents (1238) of the build chamber (1202); Item 80. The additive manufacturing system of item 79, further comprising: [Section 84] 84. The additive manufacturing system of claim 83, wherein the vacuum pump (1242) is configured to stop the vacuum on the exit path (1236) of the build chamber (1202) after a predetermined time based on the predicted completion of the purge. [Section 85] 80. The additive manufacturing system of claim 79, wherein the exit port (1234) is configured to close the exit path (1236) from the build chamber (1202) after a predetermined time to seal the build chamber (1202) during the additive manufacturing process. [Section 86] Item 79. The additive manufacturing system of item 78, wherein the gas manifold assembly (1302) further includes at least one reactant gas inlet (1312) and at least one reactant gas outlet (1314), the at least one reactant gas inlet (1312) receiving the at least one reactant gas (1224) from the at least one second gas source (1226) at a first reactant gas inlet (1316), the gas manifold assembly (1302) directing the first reactant gas inlet (1316) to a first reactant gas outlet (1318), and the gas manifold assembly (1302) delivering the at least one reactant gas (1224) to the build chamber (1202) via the first reactant gas outlet (1318) to establish the reactive atmosphere (1230). [Section 87] The build chamber (1202) at least one supply conduit (1244) coupled to the first reactant gas outlet (1318) of the manifold assembly (1302), the at least one supply conduit (1244) directing the at least one inert gas (1220) and the at least one reactant gas (1224) to a location within the build chamber (1202) proximate to the molten material as the molten material is being deposited for a current layer on the substrate (1212) or the metal article (200); Item 87. An additive manufacturing system as described in Item 86, comprising: [Section 88] The build chamber (1202) an outlet port (1234) that opens an outlet path (1236) from the build chamber (1202) for purging the gaseous contents (1238) of the build chamber (1202) in conjunction with the step of delivering the at least one inert gas (1220) and the at least one reactive gas (1224) to the build chamber (1202); Item 87. An additive manufacturing system as described in Item 86, comprising: [Section 89] Item 89. The additive manufacturing system of item 88, wherein the outlet port (1234) is configured to remain open during the additive manufacturing process such that the outlet path (1236) remains open to allow continuous flow of the at least one inert gas (1220) and the at least one reactive gas (1224) into the build chamber (1202). [Section 90] The gas manifold assembly (1302) further includes at least one reactant gas inlet (1312) and at least one reactant gas mixture outlet (1320), the at least one inert gas inlet (1304) receives the at least one inert gas (1220) at a second inert gas inlet (1322), the at least one reactant gas inlet (1312) receives the at least one reactant gas (1224) at a second reactant gas inlet (1324), and the gas manifold assembly (1302) receives the at least one inert gas (1220) at the second inert gas inlet (1322). 87. The additive manufacturing system of claim 86, wherein the inert gas (1220) is mixed with the at least one reactant gas (1224) received at the second reactant gas inlet (1324) to form a predetermined reactant gas mixture (1227), and the gas manifold assembly (1302) directs the predetermined reactant gas mixture (1227) to a first reactant gas mixture outlet (1326), and the gas manifold assembly (1302) delivers the predetermined reactant gas mixture (1227) to the build chamber (1202) via the first reactant gas mixture outlet (1326) to establish the reactive atmosphere (1230). [Section 91] The build chamber (1202) at least one supply conduit (1244) coupled to the first reactant gas mixture outlet (1326) of the manifold assembly (1302), the at least one supply conduit (1244) directing the predetermined reactant gas mixture (1227) to a location within the build chamber (1202) proximate to the molten material as the molten material is being deposited for a current layer on the substrate (1212) or the metal article (200); Item 91. An additive manufacturing system according to item 90, comprising: [Section 92] The build chamber (1202) an outlet port (1234) that opens an outlet path (1236) from the build chamber (1202) for purging the gaseous contents (1238) of the build chamber (1202) in conjunction with the step of delivering the at least one inert gas (1220) and the at least one reactive gas (1224) to the build chamber (1202); Item 91. An additive manufacturing system according to item 90, comprising: [Section 93] 93. The additive manufacturing system of claim 92, wherein the outlet port (1234) is configured to remain open during the additive manufacturing process such that the outlet path (1236) remains open to allow continuous flow of the at least one inert gas (1220) and the at least one reactive gas (1224) into the build chamber (1202). [Section 94] 79. The additive manufacturing system of claim 78, wherein the gas manifold assembly (1302) further comprises at least one reactant gas mixture inlet (1328) and at least one reactant gas mixture outlet (1320), the at least one reactant gas mixture inlet (1328) receiving a predetermined reactant gas mixture (1227) at a first reactant gas mixture inlet (1330), the gas manifold assembly (1302) directing the predetermined reactant gas mixture (1227) to a second reactant gas mixture outlet (1332), and the gas manifold assembly (1302) sending the predetermined reactant gas mixture (1227) to the build chamber (1202) via the second reactant gas mixture outlet (1332) to establish the reactive atmosphere (1230). [Section 95] The build chamber (1202) at least one supply conduit (1244) coupled to the second reactant gas mixture outlet (1332) of the manifold assembly (1302), the at least one supply conduit (1244) directing the at least one predetermined reactant gas mixture (1227) to a location within the build chamber (1202) proximate to the molten material as the molten material is being deposited for a current layer on the substrate (1212) or the metal article (200); Item 95. An additive manufacturing system as described in Item 94, comprising: [Section 96] The build chamber (1202) an outlet port (1234) opening an outlet path (1236) from said build chamber (1202) for purging the gaseous contents (1238) of said build chamber (1202) in conjunction with said step of delivering said at least one predetermined reaction gas mixture (1227) to said build chamber (1202); Item 95. An additive manufacturing system as described in Item 94, comprising: [Section 97] 97. The additive manufacturing system of claim 96, wherein the outlet port (1234) is configured to remain open during the additive manufacturing process such that the outlet path (1236) remains open to enable continuous flow of the at least one inert gas (1220) and the at least one predetermined reaction gas mixture (1227) into one or more of the build chambers (1202). [Section 98] 53. The additive manufacturing system of claim 52, wherein the energy source (1216) is configured to form a molten pool in conjunction with the step (104) of melting the metal material (1208) as the molten material is deposited for a current layer on the substrate (1212) or on the metal article (200). [Section 99] Item 99. The additive manufacturing system of item 98, wherein the system control assembly (1218) is configured to control at least one parameter of the molten pool to manage the chemical reaction that hardens the at least one selected portion (204) of the plurality of selected layers (206) of the metal article (200). [Section 100] 100. The additive manufacturing system of claim 99, wherein the at least one parameter of the molten pool includes at least one of metal pool size, metal pool temperature, and transition time from molten material to solidification. [Section 101] 53. The additive manufacturing system of claim 52, wherein the system control assembly (1218) alternates between the step (102) of establishing the non-reactive atmosphere (1228) and the step (102) of establishing the reactive atmosphere (1230) during the step (104) of melting the metal material (1208) to deposit molten material that does not harden during the non-reactive atmosphere (1228) and to deposit molten material that hardens during the reactive atmosphere (1230), such that the metal article (200) includes a first region in which at least certain portions of the successive layer harden and a second region in which at least other portions of the successive layer do not harden. [Section 102] The additive manufacturing system of claim 101, wherein the system control assembly (1218) is configured to perform the step (104) of melting the metal material (1208) for depositing molten material into the plurality of layers (202) to build the metal article (200), as well as to pause the translational motion provided by the translation assembly (1210) at selected points where there is a predetermined transition from the non-reactive atmosphere (1228) to the reactive atmosphere (1230) and vice versa. [Section 103] Item 103. The additive manufacturing system of item 102, wherein the system control assembly (1218) is configured to store or access a three-dimensional digital model (1232) of the metal article (200) in which the selected locations and the predetermined transitions are based on corresponding locations designated for hardening. [Explanation of symbols]

[0080] 100 ways 200 Metal articles 202 layers 204 Selection 206 Selection Layer 208 Remaining 210 Remaining Layers 300 ways 400 ways 600 ways 700 methods 800 ways 900 ways 1000 ways 1100 methods 1200 Additive Manufacturing System 1202 Construction Chamber 1204 Controlled Environment 1206 Material Handling Assembly 1208 Metal materials 1210 Translation Assembly 1212 Board 1214 Energy Source Assembly 1216 Energy Source 1218 System Control Assembly 1220 Inert gas 1222 First Gas Source 1224 Reactive gas 1226 Secondary Gas Source 1227 Reactive Gas Mixture 1228 Non-reactive atmosphere 1229 Mixed Gas Supply Source 1230 Reactive atmosphere 1232 3D Digital Model 1234 Exit Port 1236 Exit Route 1238 Gaseous contents 1240 Exhaust duct 1242 Vacuum Pump 1244 Supply Conduit 1246 Gas Jet 1302 Gas Manifold Assembly 1304 Inert gas inlet 1306 Inert gas outlet 1308 First inert gas inlet 1310 First inert gas outlet 1312 Reaction gas inlet 1314 Reaction gas outlet 1316 First reactive gas inlet 1318 first reactive gas outlet, first reactive gas outlet 1320 Reactant gas mixture outlet 1322 Second inert gas inlet 1324 Second reactant gas inlet 1326 first reactant gas mixture outlet 1328 Reactant gas mixture inlet 1330 first reactant gas mixture inlet 1332 second reactant gas mixture outlet 2000 Maintenance and Inspection Methods 2100 aircraft 2102 Aircraft 2104 Upper System 2106 Internal 2108 Propulsion System 2110 Electrical Systems 2112 Hydraulic System 2114 Environmental Systems

Claims

1. A method (100) for hardening a selected portion of a metal article (200), the method (100) comprising: Establishing (102) a non-reactive atmosphere (1228) in a build chamber (1202) of an additive manufacturing system (1200); melting (104) a metal material (1208) using the energy source (1216) to deposit the molten material in a plurality of layers (202) to build up the metal article (200) in conjunction with controlling translational motion of at least one of the metal article (200) and an energy source (1216) based on predetermined locations for depositing the molten material; selectively establishing (106) a reactive atmosphere (1230) within the build chamber (1202) that induces a chemical reaction in conjunction with the melting (104) and subsequent solidification of the molten material to harden at least one selected portion (204) of each layer within a plurality of selected layers (206) of the plurality of layers (202); A method (100) comprising:

2. The method of claim 1 , wherein the non-reactive atmosphere (1228) comprises at least one inert gas (1220).

3. 2. The method of claim 1, wherein, in association with the additive manufacturing process, the metallic material (1208) comprises at least one of a metal powder and a metal wire.

4. The method of claim 1, wherein the metallic material (1208) comprises at least one of titanium, a titanium alloy, steel, a corrosion resistant steel, a precipitation hardened corrosion resistant steel, a maraging steel, and a steel alloy.

5. 2. The method of claim 1, wherein at least one parameter of the translational motion of the metal article (200), the translational motion of the energy source (1216), and the operation of the energy source (1216) are controlled to manage the chemical reaction that hardens the at least one selected portion (204) of the plurality of selective layers (206) of the metal article (200).

6. The method of claim 1 , wherein the translational motion of the metal article (200) and / or the energy source (1216) comprises control of linear motion in at least one of an X-axis, a Y-axis, and a Z-axis.

7. The method of claim 1, wherein the reactive atmosphere (1230) comprises a predetermined reactive gas mixture (1227) of at least one inert gas (1220) and at least one reactive gas (1224).

8. The method of claim 7 , wherein the chemical reaction comprises nitridation.

9. The method of claim 7 , wherein the chemical reaction comprises carbonization.

10. 2. The method of claim 1, wherein each selected portion (204) of the metal article (200) to be hardened is based on a corresponding location within a three-dimensional digital model (1232) of the metal article (200) designated for hardening.

11. 2. The method of claim 1, wherein the at least one selected portion (204) of each layer of a plurality of selected layers (206) of the metal article (200) to be hardened comprises one or more regions in which portions of successive layers are hardened.

12. 2. The method of claim 1, wherein the steps of establishing the non-reactive atmosphere (1228) and selectively establishing the reactive atmosphere (1230) are repeated during the step of melting the metallic material (1208) to deposit molten material in the plurality of layers (202) until the metallic article (200) is completed.

13. Receiving (302) at least one inert gas (1220) from at least one first gas source (1222); delivering (304) the at least one inert gas (1220) to the build chamber (1202) to establish the non-reactive atmosphere (1228); The method of claim 1, further comprising:

14. The step (104) of melting the metallic material (1208) comprises: forming a molten pool (502) as the molten material is deposited on a substrate (1212) or on the metal article (200) for a current layer; 2. The method of claim 1, comprising:

15. Receiving (602) at least one inert gas (1220) from at least one first gas source (1222) and at least one reactive gas (1224) from at least one second gas source (1226); delivering (604) the at least one inert gas (1220) and the at least one reactive gas (1224) to the build chamber (1202) to establish the reactive atmosphere (1230); The method of claim 1, further comprising:

16. Receiving (902) at least one predetermined reactant gas mixture (1227) from at least one mixed gas source (1229); delivering (904) the at least one predetermined reactive gas mixture (1227) to the build chamber (1202) to establish the reactive atmosphere (1230); The method of claim 1, further comprising:

17. alternating (1002) between establishing (102) the non-reactive atmosphere (1228) and selectively establishing (106) the reactive atmosphere (1230) during the step (104) of melting the metallic material (1208) to deposit a molten material that does not harden during the non-reactive atmosphere (1228) and to deposit a molten material that hardens during the reactive atmosphere (1230), such that the metallic article (200) includes a first region in which at least certain portions of the continuous layer harden and a second region in which at least other portions of the continuous layer do not harden. The method of claim 1, further comprising:

18. heat treating (1102) the metal article (200) after completion of the additive manufacturing process to optimize hardening of the selected portions of the metal article hardened during the additive manufacturing process; machining (1104) the metal article (200) to create a finish on the metal article (200); The method of claim 1, further comprising:

19. 1. An additive manufacturing system (1200) for hardening a selected portion of a metal article (200), the additive manufacturing system comprising: a build chamber (1202) that provides a controlled environment (1204) for additive manufacturing of the metal article (200); a material handling assembly (1206) for delivering a metal material (1208) into the build chamber (1202) in conjunction with an additive manufacturing process; a substrate (1212) for at least temporarily supporting the metal article (200) during the additive manufacturing process; an energy source assembly (1214) for melting the metallic material (1208) using an energy source (1216) and depositing the molten material in a plurality of layers (202) to build the metallic article (200) on the substrate (1212); a translation assembly (1210) for providing translational motion of at least one of the substrate (1212) and the energy source assembly (1214) based on predetermined locations for depositing the molten material in conjunction with the additive manufacturing process; a system control assembly (1218) in operative communication with the material handling assembly (1206), the energy source assembly (1214), and the translating assembly (1210), the system control assembly (1218) controlling the establishment of a non-reactive atmosphere (1228) in the build chamber (1202), controlling the delivery of the metallic material (1208) by the material handling assembly (1206), controlling the melting (104) of the metallic material (1208) by the energy source (1216) in conjunction with controlling the translating assembly (1210), and controlling the selective establishment of a reactive atmosphere (1230) in the build chamber (1202) to effect a chemical reaction and harden at least one selected portion (204) of each layer in a plurality of selected layers (206) of the plurality of layers (202) in conjunction with the melting (104) and subsequent solidification of the molten material; An additive manufacturing system (1200).

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