Methods of producing wrought products with internal passages

Abstract

Various methods are disclosed for additively manufacturing a feedstock material to create an AM preform, wherein the AM preform is configured with a body having an internal passage defined therein, wherein the internal passage further includes at least one of a void and a channel; inserting a filler material into the internal passage of the AM preform; closing the AM preform with an enclosure component such that the filler material is retained within the internal passage of the AM preform; and deforming the AM preform to a sufficient amount to create a product having an internal passage therein, wherein the product is configured with wrought properties for that material via the deforming step.

Claims

1. A method comprising: (a) additively manufacturing an additively manufactured (AM) preform, wherein the AM preform comprises an internal passage within a body of the AM preform, wherein the internal passage comprises at least one of a void and a channel; (b) inserting a filler material into the internal passage of the AM preform; (c) closing the AM preform with an enclosure component such that the filler material is retained within the internal passage of the AM preform; and (d) creating a wrought product having the internal passage therein from the AM preform, wherein the creating comprises hot working the AM preform.

2. The method of claim 1, wherein the closing step comprises sealing the filler material within the AM preform via an enclosure component.

3. The method of claim 1, wherein the closing step comprises welding an opening of the internal passage, thereby enclosing the filler material within the AM preform.

4. The method of claim 1, wherein the internal passage comprises an opening, and wherein the closing step comprises pressing a plug into the opening to retain the filler material within the internal passage.

5. The method of claim 1, wherein the closing step comprises enclosing the filler material in the internal passage via successive additively manufactured build layers.

6. The method of claim 1, wherein the hot working comprises forging.

7. The method of claim 6, wherein the forging comprises using a single die forging.

8. The method of claim 1, wherein the hot working comprises rolling.

9. The method of claim 1, wherein the hot working comprises ring rolling.

10. The method of claim 1, wherein the hot working comprises extruding.

11. The method of claim 1, comprising: removing the filler material from the internal passage of the wrought product.

12. The method of claim 11, wherein the removing step comprises: melting the filler material; and draining the filler material from the wrought product.

13. The method of claim 1, comprising annealing at least one of the AM preform and the wrought product.

14. The method of claim 1, comprising cold working at least one of the AM preform and the wrought product.

15. The method of claim 1, comprising at least one of (i) machining the wrought product, (ii) polishing the wrought product, and (iii) surface finishing the wrought product.

16. The method of claim 15, wherein the creating step comprises: prior to the hot working, preheating the AM preform, thereby melting the filler material within the internal passage.

17. The method of claim 1, comprising: solidifying the filler material and then completing the creating step (d).

18. The method of claim 1, wherein the filler material comprises a material different than the AM preform.

19. The method of claim 18, wherein the filler material comprises at least one of an oil, polymer, organic solvent, inorganic solvent, metal or metal alloy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic of an embodiment of the FEM modeling completed to design an AM preform having a body dimension and internal passage dimension configured to undergo deformation (i.e. with a filler material retained within the internal passage) and provide a product form having a final body dimension and internal passage dimension, in accordance with the instant disclosure.

(2) FIG. 2 depicts a cut away side view of a portion of the computer model results of the initial geometry of the AM preform (left) and final geometry of the product (right) expected utilizing the computer modeling approach, in accordance with one or more embodiments of the instant disclosure.

(3) FIG. 3 is a graph depicting the computer modeled flow curve during deformation at 300 C. and a strain rate of 0.005/sec, showing stress (MPa) as a function of Strain. As depicted in FIG. 3, upon straining (deforming) the AM preform, Stress immediately, sharply increases and levels off to about 115 MPa at approximately 0.02-0.03.

(4) FIG. 4 provides two top view photographs depicting embodiments of two products made via a deformation step at 300 C. (i.e. with filler material initially retained within the cavity), in accordance with the disclosure. Referring to FIG. 4, the mechanically sealed AM preform exhibited leaking of filler material, as did the welded plug seals depicted on the right.

(5) FIG. 5 depicts two photographs of cross-sectional views of the embodiments of the products from FIG. 4, depicting the filler material retained in the internal passages, although some leaking was observed adjacent to the enclosure component (e.g. mechanical seal/interference plug and welded seal/plug), in accordance with the instant disclosure. Without being bound by any particular mechanism or theory, it is believed that the collapse of feed passages and cracking of internal passages shown in FIG. 5 is attributable to the failure of the seals (leaking) depicted in FIG. 4.

(6) FIG. 6 depicts a top plan view photograph of the product deformed at 200 C., under constant load conditions, in accordance with the instant disclosure. Since the filler material was deformed at temperature conditions where the filler was solid, no leaking occurred.

(7) FIG. 7 depicts photographs of cross sections of two embodiments in accordance with the instant disclosure. On the left, a proxy for the before AM preform is depicted, wherein the AM preform body is a control AM preform (that did not undergo a deformation step prior to cross-sectioning), where the AM preform is configured with preform body dimensions (i.e. slightly concave sidewalls along the non-deformation surface of the body) and preform internal passage dimensions (i.e. elliptically shaped void), where the fill material is shown filling the internal passage (e.g. channels and void), further wherein the interference plugs are shown extending, from the upper surface of the body into the opening of the internal passage (and extending down into a given distance into the channel). On the right, the image of the cross-section of the embodiment of the product after deformation step is in stark contrast with the before AM preform on the left. More specifically, the product or after embodiment shows product body dimensions with as shorter height of the product, and the concave walls of the AM preform have been directed in an outward direction to a near perpendicular when compared to the product body top and bottom surfaces. Moreover, the internal passage is configured with product internal passage dimensions (i.e. the void was transformed by deformation from an elliptical shape to a circular shape), and the channels have also undergone axial shrinking and a slight increase in perceived diameter of the channel, via the deformation step. As can be seen from FIG. 7, the internal cavities deformed uniformly and there was no minimal evidence of cavity collapse or cracking in the passages.

(8) FIG. 8 depicts the embodiments of FIG. 7, once the filler material was removed (melted and removed) from the internal passage (e.g. void and channels). As visually observable, after removing the filler material (tin) there was little to no chemical reactivity and/or wettability of materials. Also, it is noted the integrity of feed passages was maintained after deformation and there was minimal (if any) cracking observed in the internal passages.

(9) FIG. 9 depicts the real profile of the samples before and after deformation. Without being bound by a particular mechanism and/or theory, it is believed that the slight bar cling visually observable after deformation is attributable to the friction between the platens and the work piece.

(10) FIG. 10 depicts a schematic cross-sectional view of an embodiment of the method, depicting the steps of creating (designing) an AM preform based on the final product specifications (body dimension and internal passage dimension), additively manufacturing an AM preform having the body dimensions and internal passage dimensions inserting (and enclosing) the filler material within the AM preform, and deforming the AM preform to create a product having the product specifications (body dimension and internal passage dimension) after deforming, in accordance with the instant disclosure.

(11) FIG. 11 depicts a cut-away side view of an AM preform with preform extensions configured away from deformation faces of the body filled with solid filler material. As depicted in FIG. 11, the cap enclosures are also configured outside elm, from the deformation faces.

DETAILED DESCRIPTION

(12) A series of experiments were completed in order to evaluate the several of the embodiments of the instant disclosure.

Example: Computer Modeling of AM Preform and Product

(13) A computer modeling approach was evaluated to select parameters of the AM preform (e.g. body dimension and void dimension) to provide a resulting product having a product body dimension and product void dimension. Finite Element Modeling was completed, such that reverse shape modeling was used to account for the deformation and initial (AM preform) vs. final (product) boundary conditions (body dimensions and void dimensions) in the components.

(14) A true strain of 50% was selected as a bogie for validation and it was assumed that there was no die friction, that the cavity was filled (i.e. completely filled) with an incompressible fluid, and that incompressible filler material was retained in the AM preform via sealing (e.g. enclosure sufficient to retain the filler material during deformation conditions). A final internal passage (void) in the product was targeted to be a 0.25 diameter circle (D=0.25). Accordingly, an elliptical shape with the cross sectional area of the desired circle size a id aspect ratio necessary to become circular after deformation was calculated as shown in FIG. 1. The initial shape (of body and internal passage, including void and channel) was estimated by a trial and error procedure to obtain a near straight edge after deformation and a circular shape for the internal passages.

(15) FIG. 1 is a schematic of an embodiment of the FEM modeling completed to design an AM preform having a body dimension and internal passage dimension configured to undergo deformation (i.e. with a filler material retained within the internal passage) and provide a product form having a final body dimension and internal passage dimension initial geometry of the AM component, in accordance with the instant disclosure. Depicted in FIG. 1 is the cut-away side view of an engineering drawing of the AM preform designed in the corresponding Example section, a table depicting some of the parameters of the AM preform (e.g. dimensions), a mathematical algorithm utilized in the FEM modeling, and a perspective cut away view of the cross-section depicted in the engineering drawing, depicting the differing three-dimensional depths of the void and the channels of the internal passage, as well as the concavity of the body sidewall (e.g., at the non-deformation surface sidewall), accordance with one or more embodiments of the instant disclosure.

(16) FIG. 2 depicts a cut away side view of a portion of the computer model results of the initial geometry of the AM preform (left) and final geometry of the product (right) expected utilizing the computer modeling approach, in accordance with one or more embodiments of the instant disclosure. With reference to FIG. 2, the initial geometry and final expected geometry are depicted after deformation, under isothermal conditions, and frictionless axisymmetric compression. FIG. 2 (initial vs. final) contrasts the different external shape profile (loss of concavity of sidewall from preform to product) as well as the change in shape of the internal cavity (preform depicts an elliptical portion vs. product depicts a circular portion).

Example: AM Preform Build with Filler Material (Incompressible Material)

(17) Four identical AM preforms were additively manufactured using a laser powder bed additive manufacturing process on the EOS M280. The feedstock material used to make the parts was an AlSi10Mg alloy powder.

(18) A 2 diameter and 2 high cylindrical sample was chosen as a prototype sample for experimental validation, based on factors including internal passage size and tonnage limit on the deformation simulator. Each AM preform was configured with a concentric internal void, where the void was configured with two corresponding channels configured to communicate from the void to the surface of the body of the AM preform. The two vertical passages (channels) in the AM preforms were utilized to enable filling the cavity via one channel while and the other to bleeding the air during filling and ensure a proper and complete fill.

(19) Three of the AM preforms were heated to a temperature of 325 C. and then filled with a filler material using a tin feed rod of 0.125 inch diameter which melted in situ (in the cavity). Complete fill was confirmed by visually observing molten tin from the bleed passage (i.e. second channel). The feed and bleed ports (channels) were closed (e.g. sealed) either by: plugs with interference fit or by plugging the openings of the channels and then welding them with 6061 filler alloy.

Example: AM Preform Deformation

(20) A deformation simulator was utilized on the three AM preforms. The deformation simulator was a compression machine (press) with a capacity of 150,000 lbs, configured with a furnace to heat the press surfaces and/or AM preform to deform via hot compression. The deformation simulator of this experimental section was utilized as a proxy for a single step forging die, where the simulator allowed for control over temperature, strain rate and strain of the AM preform to make a product having wrought properties.

(21) During deformation, the furnace was heated up to the indicated temperature and deformation was completed (e.g. with heated surfaces of the press). In addition, there were PTFE polymer sheets configured between the AM preform deformation surfaces (upper and lower surfaces of the AM preform) and the press surfaces to promote frictionless surfaces of deformation. The estimated internal hydrostatic pressure was 5.5 KSI, and it is noted that the hydrostatic pressure during uniaxial deformation is about of the applied flow stress.

(22) Two samples tone with an interference fit plug and one with welded plugs) were then deformed in axisymmetric compression at 300 C. and a strain rate of 0.005/sec. A hold time of 30 minutes prior to deformation was provided to ensure that the tin filler was completed melted prior to deformation. FIG. 3 shows the flow curve as measured during deformation.

(23) As can be seen in FIG. 5, molten tin is depicted on top of the product, which indicates that leakage occurred. Without being bound by a particular mechanism or theory, the leakage of molten tin during deformation is believed to be the cause of the resulting collapse of the cavity and/or cracking of the cavity (i.e. leaking resulted in uncontrolled distortion of the internal passages during deformation).

(24) The third sample was deformed in the deformation simulator at a temperature of 200 C., such that the filler material (tin) was maintained in a solid state during deformation in order to prevent escape from the cavity/void (leaking). This experiment was completed under constant load, as the maximum tonnage on the simulator was exceeded in maintaining the desired strain rate of 0.005/sec. As shown in FIG. 6, there was no evidence of any molten tin leakage on the top surface of the product.

(25) It was observed that filling the cavity (internal passage) with a molten filler material which solidifies before/during deformation provided a suitable product and corresponding cavity. Also, while it was observed that both molten filler material runs leaked, it was unclear if each of the seals was complete/appeared as sufficient prior to deformation, such that it would be expected to retain the molten filler material during deformation at a pressure of 5.5 KSI.

(26) Based on the above experiments, without being bound by any particular mechanism or theory, it is believed that deformation of AM preforms with molten filler material configured in (e.g. enclosed and/or sealed within) at least one internal passage(s) will result in products having internal passages (e.g. voids and/or channels) in accordance with the instant disclosure, so long as sufficient enclosures/seals of the molten filler material are in place prior to (and during) deformation.

Prophetic Example: Enclosure of Fill Material with AM Build Layers in AM Preform

(27) As an alternative embodiment, the filler material is enclosed in the internal passage of an AM preform during the AM build process. More specifically, a filler material is added to an AM preform, (if needed) allowed to solidify, and then additive manufacturing is resumed, such that additional build layers are configured over the opening to form an AM enclosure that retains the filler material within the AM preform.

(28) In yet another embodiment, if the filler material is liquid at additive manufacturing conditions, then a cover (e.g. substrate configured to extend across the opening of the internal passage) is fitted into/onto the opening, followed by successive additive manufacturing build layers to enclose the filler material into the internal passage.

(29) In another embodiment, after the filler material is added to the internal passage, the opening is capped (e.g. with a small plug), the surface is milled (i.e. to create a continuous build surface) and then returned to the additive machine to deposit at least one additional build layer onto the cap (and/or over the surface of the body that is configured with the opening of the internal passage).

(30) In one or more of these embodiments, additional build layers are configured to provide an enclosure with a predetermined thickness (i.e. sufficient to retain the filler material in the internal passage while undergoing the deformation step).

REFERENCE NUMBERS

(31) AM preform 10 Body 12 Preform body dimension 14 Internal passage (e.g. void+channel) 16 Void 18 Preform void dimension 20 Channel 22 Channel dimension 22 Opening 24 Enclosure 26 Cap (e.g. plug) 28 Weld 30 AM cover 32 Filler material (e.g. incompressible material) 34 Solid 36 Liquid (e.g. molten or liquid) 38 Within body: Deformation faces/surface onto which deformation step is applied: 40 (e.g. 40, 40) Preform extension (e.g. configured for channel and/cap outside of deformation zone, not on deformation face/surface) 42 Product 50 Product body dimension 46 Product void dimension 48