Devices and Methods for Performing Shear-Assisted Extrusion and Extrusion Processes
20230150022 · 2023-05-18
Inventors
- Scott A. Whalen (West Richland, WA, US)
- Jens T. Darsell (West Richland, WA, US)
- MD. Reza-E-Rabby (Richland, WA, US)
- Brandon Scott Taysom (West Richland, WA, US)
- Tianhao Wang (Richland, WA, US)
- Darrell R. Herling (Kennewick, WA, US)
- Xiao Li (Richland, WA, US)
Cpc classification
C22C1/05
CHEMISTRY; METALLURGY
B22F1/12
PERFORMING OPERATIONS; TRANSPORTING
B22F2999/00
PERFORMING OPERATIONS; TRANSPORTING
B22F2998/10
PERFORMING OPERATIONS; TRANSPORTING
B21C23/002
PERFORMING OPERATIONS; TRANSPORTING
B22F3/24
PERFORMING OPERATIONS; TRANSPORTING
B22F1/12
PERFORMING OPERATIONS; TRANSPORTING
B21C23/205
PERFORMING OPERATIONS; TRANSPORTING
C22C1/05
CHEMISTRY; METALLURGY
B21C23/001
PERFORMING OPERATIONS; TRANSPORTING
B22F2998/10
PERFORMING OPERATIONS; TRANSPORTING
B22F2999/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
A method for preparing a shear-assisted extruded material from a powder billet is provided, the method comprising providing a billet of material in substantially powder form; applying both axial and rotational pressure to the material to deform at least some of the contacted material; and extruding the material to form an extruded material. A method for preparing shear-assisted extruded material is provided, the method comprising applying both axial and rotational pressure to stock material to form an extruded material at a rate between 2 and 13 m/min. A method for preparing shear-assisted extruded material is provided. The method comprises applying both axial and rotational pressure to stock material to form an extruded material; and aging the extruded material for less than 3 hours. A method for preparing shear-assisted extruded material is provided. The method comprises providing a stock material for shear-assisted extrusion; and applying both axial and rotational force to the stock material to form an extruded material, wherein the axial force does not decrease during the extrusion.
Claims
1. A method for preparing an extruded material by shear assisted processing and extrusion from a powder billet, the method comprising: providing a billet of material in substantially powder form; applying both axial and rotational pressure to the material to deform at least some of the material; and extruding the material to form an extruded material.
2. The method of claim 1 wherein the billet material is loose powder.
3. The method of claim 1 wherein the billet material comprises Al.
4. The method of claim 1 wherein the billet material comprises one or more of Al, Mg, Fe, Si, and/or Zr.
5. The method of claim 4 wherein the extruded material comprises an alloy.
6. The method of claim 1 wherein the billet material in powder form can have a maximum particle size of 100 um.
7. The method of claim 1 wherein the billet material in powder form can have a particle size greater than 100 um.
8. The method of claim 1 further comprising using an extrusion die defining spiral grooves.
9. The method of claim 1 wherein individual particles of the powder include an oxide or ceramic component.
10. The method of claim 1 wherein the extruded material has a tensile strength from about 220 MPa to about 360 MPa.
11-20. (canceled)
21. A method for preparing extruded material by shear assisted processing and extrusion, the method comprising: applying both axial and rotational pressure to stock material to form an extruded material; and aging the extruded material for less than 3 hours.
22. The method of claim 21 wherein the stock material is in powder form.
23. The method of claim 21 wherein the stock material is defined by castings.
24. The method of claim 21 wherein the stock material comprises powder, flake, chip, or scrap.
25. The method of claim 21 wherein the stock material comprises Al.
26. The method of claim 21 wherein the extruded material has a hardness of at least 155 HV after the 3 hrs.
27. The method of claim 21 further comprising solution heating the extruded material before the aging.
28. A method for preparing extruded material by shear assisted processing and extrusion, the method comprising: providing a stock material for shear-assisted extrusion; and applying both axial and rotational force to the stock material to form an extruded material, wherein the axial force does not decrease during the extrusion.
29. The method of claim 28 further comprising initiating an initial axial force upon a stock material; maintaining a steady state axial force upon the stock material; and reducing the axial force upon stock material depletion.
30. The method of claim 29 wherein the stead state axial force is greater than the initial axial force.
31. The method of claim 29 further comprising a transition between the initial axial force and the steady state axial force, the transition having a position slope when plotted.
32. The method of claim 28 further comprising ramping the initial axial force to the steady state axial force.
33. The method of claim 32 further comprising decreasing rotational rpms while increasing ramping of ram speed.
34. The method of claim 29 further comprising maintaining a die face temperature during steady force application at a substantially constant temperature.
35. The method of claim 34 wherein the temperature is about 400° C.
Description
DRAWINGS
[0044] Embodiments of the disclosure are described below with reference to the following accompanying drawings.
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DESCRIPTION
[0116] This disclosure is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).
[0117] The following description including the attached pages provide various examples of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
[0118] In the previously described and related applications various methods and techniques are described wherein the described technique and device (referred to as ShAPE) is shown to provide a number of significant advantages including the ability to control microstructure such as crystallographic texture through the cross sectional thickness, while also providing the ability to perform various other tasks. In this description we provide information regarding the use of the ShAPE technique to form materials with non-circular hollow profiles as well as methods for creating high entropy alloys that are useful in a variety of applications such as projectiles. Exemplary applications will be discussed on more detail in the following.
[0119] Referring first now to
[0120] This arrangement is distinct from and provides a variety of advantages over the prior art methods for extrusion. First, during the extrusion process the force rises to a peak in the beginning and then falls off once the extrusion starts. This is called breakthrough. In this ShAPE process the temperature at the point of breakthrough is very low. For example for Mg tubing, the temperature at breakthrough for the 2″ OD, 75 mil wall thickness ZK60 tubes is <150 C. This lower temperature breakthrough is believed in part to account for the superior configuration and performance of the resulting extrusion products.
[0121] Another feature is the low extrusion coefficient kf which describes the resistance to extrusion (i.e. lower kf means lower extrusion force/pressure). Kf is calculated to be 2.55 MPa and 2.43 MPa for the extrusions made from ZK60-T5 bar and ZK60 cast respectively (2″ OD, 75 mil wall thickness). The ram force and kf are remarkably low compared to conventionally extruded magnesium where kf ranges from 68.9-137.9 MPa. As such, the ShAPE process achieved a 20-50 times reduction in kf (as thus ram force) compared to conventional extrusion. This assists not only with regard to the performance of the resulting materials but also reduced energy consumption required for fabrication. For example, the electrical power required to extrude the ZK60-T5 bar and ZK60 cast (2″ OD, 750 mil wall thickness) tubes is 11.5 kW during the process. This is much lower than a conventional approach that uses heated containers/billets. Similar reductions in kf have also been observed when extruding high performance aluminum powder directing into wire, rod, and tubing.
[0122] The ShAPE process is significantly different than Friction Stir Back Extrusion (FSBE). In FSBE, a spinning mandrel is rammed into a contained billet, much like a drilling operation. Scrolled grooves force material outward and material back extrudes around and onto the mandrel to form a tube, not having been forced through a die. As a result, only very small extrusion ratios are possible, the tube is not fully processed through the wall thickness, the extrudate is not able to push off of the mandrel, and the tube length is limited to the length of the mandrel. In contrast, ShAPE utilizes spiral grooves on a die face to feed material inward through a die and around a mandrel that is traveling in the same direction as the extrudate. As such, a much larger outer diameter and extrusion ratio are possible, the material is uniformly process through the wall thickness, the extrudate is free to push off the mandrel as in conventional extrusion, and the extrudate length is only limited only by the starting volume of the billet. ShAPE can be scalable to the manufacturing level, while the limitations of FSBE have kept the technology as a non-scalable academic interest since FBSE was first reported.
[0123] An example of an arrangement using a ShAPE device and a mandrel 18 is shown in
[0124] The ShAPE process has been utilized to form various structures from a variety of materials including the arrangement as described in the following table.
TABLE-US-00001 TABLE 1 Alloy Material Class Precursor Form PUCKS Bi.sub.2Te.sub.3 Thermoelectric Powder Fe—Si Magnet Powder Nd.sub.2Fe.sub.11B/Fe Magnet Powder Nd.sub.2Fe.sub.14B Magnet Powder MA956 ODS Steel Powder Nb 0.95 Ti 0.05 Thermoelectric Powder Fe 1 Sb 1 Mn—Bi Magnet Powder Al—Si Model Binary Alloy Powder Cu—Ni Model Binary Alloy Powder Cu—Nb Model Binary Alloy Powder PM 2000 ODS Steel Powder Eurofer 97 ODS Steel Powder 14YWT ODS Steel Powder TUBES ZK60 Magnesium Alloy Barstock, Casting AZ31 Magnesium Alloy Barstock AZ91 Magnesium Alloy Flake, Casting AZS312 Magnesium Alloy Casting Mg-7 wt % Si Magnesium Alloy Casting AZ91- 1, 5 and 10 Mg MMC Mechanically wt. % Al.sub.2O.sub.3 Alloyed Flake AZ91- 1, 5 and 10 Mg MMC Mechanically wt. % Y.sub.2O.sub.3 Alloyed Flake AZ91- 1, 5 and 10 Mg MMC Mechanically and 5 wt. % SiC Alloyed Flake AA2024 Structural Aluminum Cast, Barstock AA6061 Structural Aluminum Cast, Barstock AA6063 Structural Aluminum Casting, Barstock and Chip AA7075 High Strength Aluminum Casting, barstock Al-12.4TM High Strength Aluminum Powder A356 Structural Aluminum Chip AA2024/1100 Aluminum Cladding Casting, barstock AA7075/AA6061 Aluminum Cladding Casting, barstock 1100/7075/1100 Aluminum Cladding Casting, barstock RODS Al—Mn wt. 15% Aluminum Manganese Casting Alloy Al—Mg Mg Al Coextrusion Barstock Mg—Dy—Nd—Zn—Zr Magnesium Rare Earth Barstock Cu Pure Copper Barstock ODS-Cu Oxide Dispersion Powder Strengthened Cu Cu-Graphite Conductive Copper Powder Cu-Graphene Conductive Copper Powder + Film Cu-Graphene Conductive Copper Barstock + Film Cu-Graphene Conductive Copper Foil + Film Al-Graphene Conductive Aluminum Powder + Film Al-Reduced Graphene Conductive Aluminum Barstock + Flake Al-Graphite Conductive Aluminum Barstock + Powder CP-Mg Pure Magnesium Barstock, casting AA6061 Aluminum Casting, barstock AA7075 Aluminum Casting, barstock Al—Ti—Mg—Cu—Fe High Entropy Alloy Casting Al- 1, 5, 10 at. % Mg Magnesium Alloy Casting Al-12.4TM High Temperature/ Powder Strength Aluminum Rhodium Pure Rhodium Barstock Al—Ce High Temperature/ Casting Strength Aluminum AA1100 Aluminum Alloy Barstock AA7XXX High Strength Aluminum Proprietary Powder 14YWT ODS Steel Powder MA956 ODS Steel Powder Bi.sub.2Te.sub.3 Thermoelectric Casting and Sintered Powder Mixed Plastic Plastic Scrap and Pellets
[0125] In addition, to the pucks, rods and tubes described above, the present disclosure also provides a description of the use of a specially configured scroll component referred by the inventors as a portal bridge die head which allows for the fabrication of ShAPE extrusions with non-circular hollow profiles. This configuration allows for making extrusion with non-circular, and multi-zoned, hollow profiles using a specially formed portal bridge die and related tooling.
[0126]
[0127] In the present embodiment grooves 13, 15 on the face 12 of the die 10 direct plasticized material toward the aperture ports 17. Plasticized material then passes through the aperture ports 12 wherein it is directed to a die bearing surface 24 within a weld chamber similar to conventional portal bridge die extrusion. In this illustrative example, material flow is separated into four distinct streams using four ports 17 as the billet and the die are forced against one another while rotating.
[0128] While the outer grooves 15 on the die face feed material inward toward the ports 17, inner grooves 13 on the die face feed material radially outward toward the ports 17. In this illustrative example, one groove 13 is feeding material radially outward toward each port 17 for a total of four outward flowing grooves. The outer grooves 15 on the die surface 12 feed material radially inward toward the port 17. In this illustrative example, two grooves are feeding material radially inward toward each port 17 for a total of eight inward feeding grooves 15. In addition to these two sets of grooves, a perimeter groove 19 on the outer perimeter of the die, shown in
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[0131] In the previously described and related applications various methods and techniques are described wherein the ShAPE technique and device is shown to provide a number of significant advantages including the ability to control microstructure such as crystallographic texture through the cross sectional thickness, while also providing the ability to perform various other tasks. In this description we provide information regarding the use of the ShAPE technique to form materials with non-circular hollow profiles as well as methods for creating high entropy alloys that are useful in a variety of applications. These two exemplary applications will be discussed on more detail in the following.
[0132]
[0133] In use, both an axial force and a rotational force are applied to a material of interest causing the material to plasticize. In extrusion applications, the plasticized material then flows over a die bearing surface dimensioned so as to allow recombination of the plasticized materials in an arrangement with superior grain size distribution and alignment than what is possible in traditional extrusion processing. As described in the prior related applications this process provides a number of advantages and features that conventional prior art extrusion processing is simply unable to achieve.
[0134] High entropy alloys are generally solid-solution alloys made of five or more principal elements in equal or near equal molar (or atomic) ratios. While this arrangement can provide various advantages, it also provides various challenges particularly in forming. While conventional alloys can comprise one principal element that largely governs the basic metallurgy of that alloy system (e.g. nickel-base alloys, titanium-base alloys, aluminum-base alloys, etc.) in an HEA each of the five (or more) constituents of HEAs can be considered as the principal element. Advances in production of such materials may open the doors to their eventual deployment in various applications. However, standard forming processes have demonstrated significant limitations in this regard. Utilization of the ShAPE type of process demonstrates promise in obtaining such a result.
[0135] In one example a “low-density” AlCuFe(Mg)Ti HEA was formed. Beginning with arc-melted alloy buttons as a pre-cursor, the ShAPE process was used to simultaneously heat, homogenize, and consolidate the HEA resulting in a material that overcame a variety of problems associated with prior art applications and provided a variety of advantages. In this specific example, HEA buttons were arc-melted in a furnace under 10.sup.−6 Torr vacuum using commercially pure aluminum, magnesium, titanium, copper and iron. Owing to the high vapor pressure of magnesium, a majority of magnesium vaporized and formed Al1Mg0.1Cu2.5Fe1Ti1.5 instead of the intended Al1Mg1Cu1Fe1Ti1 alloy. The arc melted buttons described in the paragraph above were easily crushed with a hammer and used to fill the die cavity/powder chamber (
[0136] Comparison of the arc-fused material and the materials developed under the ShAPE process demonstrated various distinctions. The arc melted buttons of the LWHEA exhibited a cored dendritic microstructure along with regions containing intermetallic particles and porosity. Using the ShAPE process these microstructural defects were eliminated to form a single phase, refined grain and no porosity LWHEA sample
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[0138] Typically such microstructures are homogenized by sustained heating for several hours to maintain a temperature near the melting point of the alloy. In the absence of thermodynamic data and diffusion kinetics for such new alloy systems the exact points of various phase formations or precipitation is difficult to predict particularly as related to various temperatures and cooling rates. Furthermore, unpredictability with regard to the persistence of intermetallic phases even after the heat treatment and the retention of their morphology causes further complications. A typical lamellar and long intermetallic phase is troublesome to deal with in conventional processing such as extrusion and rolling and is also detrimental to the mechanical properties (elongation).
[0139] The use of the ShAPE process enabled refinement of the microstructure without performing homogenization heat treatment and provides solutions to the aforementioned complications. The arc melted buttons, because of the presence of their respective porosity and the intermetallic phases, were easily fractured into small pieces to fill in the die cavity of the ShAPE apparatus. Two separate runs were performed as described in Table 1 with both the processes' yielding a puck with diameter of 25.4 mm and approximately 6 mm in height. The pucks were later sectioned at the center to evaluate the microstructure development as a function of its depth. Typically in the ShAPE consolidation process; the shearing action is responsible for deforming the structure at interface and increasing the interface temperature; which is proportional to the rpm and the torque; while at the same time the linear motion and the heat generated by the shearing causes consolidation. Depending on the time of operation and force applied near through thickness consolidation can also be attained.
TABLE-US-00002 TABLE 2 Consolidation processing conditions utilized for LWHEA Pressure Process Run # (MPa) Tool RPM Temperature Dwell Time 1 175 500 180 s 2 85 500 600° C. 180 s
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[0141] The use of the ShAPE device and technique demonstrated a novel single step method to process without preheating of the billets. The time required to homogenize the material was significantly reduced using this novel process. Based on the earlier work, the shearing action and the presence of the scrolls helped in comminution of the secondary phases and resulted in a helical pattern. All this provides significant opportunities towards cost reduction of the end product without compromising the properties and at the same time tailoring the microstructure to the desired properties. Similar accelerated homogenization has also been observed in magnesium and aluminum alloys during ShAPE of as-cast materials.
[0142] In as much as types of alloys exhibit high strength at room temperature and at elevated temperature, good machinability, high wear and corrosion resistance, such materials could be seen as a replacement in a variety of applications. A refractory HE-alloy could replace expensive super-alloys used in applications such as gas turbines and the expensive Inconel alloys used in coal gasification heat exchanger. A light-weight HE-alloy could replace aluminum and magnesium alloys for vehicles and airplanes. Use of the ShAPE process to perform extrusions would enable these types of deployments.
[0143] Referring next to
[0144] Referring next to
[0145] In accordance with example implementations, Shear assisted processing and extrusion (ShAPE™) can be used to join magnesium and aluminum alloys in a butt joint configuration. Joining can occur in the solid-phase and in the presence of shear, brittle Mg.sub.17Al.sub.12 intermetallic layers can be eliminated from the Mg—Al interface. The joint composition can transition gradually from Mg to Al, absent of Mg.sub.17Al.sub.12, which can improve mechanical properties compared to joints where Mg.sub.17Al.sub.12 interfacial layers are present.
[0146] As alluded to joining Mg—Al is difficult to perform without forming a brittle Mg.sub.17Al.sub.12 interfacial layer at the dissimilar interface. Example applications for material having been joined using the processes of the present disclosure include, but are not limited to: [0147] Lightweight of rivets and bolts (i.e. Al shank with Mg head or vice versa) [0148] Multi-material extrusion for structural members (tailor welded extrusions) [0149] Mg—Al tailor welded blanks formed by slitting and rolling thin-walled tubes [0150] Corrosion resistant joints due to galvanically graded Mg—Al interface [0151] Dissimilar Mg alloy or Al alloy joint pairs (i.e. AA6061 to AA7075) Referring to
[0152] Die tool 200 can include tool sidewalls 202 as well as die face rim 204. In
TABLE-US-00003 TABLE 3 Extrusions fabricated with differing degrees of angled scroll faces. Wall Thickness 6 Scroll 1 and 2 mm 4 Scroll, 0 deg 1 and 2 mm 4 Scroll, 14 deg 1 and 2 mm 4 Scroll, 26 deg 1 and 2 mm 4 Scroll, 45 deg 1 and 2 mm
[0153] Referring next to
[0154] Referring next to
[0155] In accordance with example implementations and with reference to
[0156] Referring next to
[0157] Referring next to
[0158] Referring next to
[0159] Referring next to
[0160] Referring next to
[0161] Referring next to
[0162] Referring next to
[0163] Referring next to
[0164] Referring next to
[0165] In accordance with example implementations, materials can be engaged using the ShAPE technology of the present disclosure. For example, Mg alloy ZK60 can be joined to Al alloy 6061, without forming an Mg.sub.17Al.sub.12 interfacial layer. To accomplish this, the ShAPE™ process can be modified to mix ZK60 and AA6061 into a fully consolidated rod having an Al rich coating as a corrosion barrier. Referring next to
[0166] Referring to
[0167] The geometry of the interlocking region can be tailored to control the composition and transition length of the Mg—Al joint region. The geometric possibilities are many but two examples are shown in
[0168] In accordance with at least one implementation, with triangular spoked interlocks 165, the composition of Mg in Al goes from 0% to 100% at a rate depending on the number of spokes and angle of the triangle's vertex. This method has been used to demonstrate a transition length of 37 mm to illustrate the concept. Because the joint is formed by mixing in the solid phase, an Mg.sub.17Al.sub.12 interfacial layer will not form. Rather, a gradient in chemical composition and also possibly grain size will form across the dissimilar interface with the intense shear refining and dispersing any Mg.sub.17Al.sub.12 second phase formations. The composition gradient at the Mg—Al interface has a secondary benefit of also being a galvanically graded interface which can improve corrosion resistance. Referring to
[0169] Accordingly, an extrusion process for forming extrusion of a desired composition from a feedstock is provided. The process can include providing feedstock for extrusion, and the feedstock comprising at least two different materials. The process can further include engaging the materials with one another within a feedstock container, with the engaging defining an interface between the two different materials as described herein. The process can include extruding the feedstock to form an extruded product. This extruded product can include a first portion that includes one of the two materials bound to a second portion that can include one of the other two materials.
[0170] Accordingly, the interface between the two materials can interlock the one material with the other material and the geometry of the interlock can define a ratio of the two materials where they are bound. This ratio can be manipulated through manipulating the geometry of the engagement. For example, there could be a small amount of one of the materials entering into a perimeter defined by the other of the two materials, and vice versa. In accordance with example implementations and specific examples, one of the materials can be Mg and the other can be Al. The process can also include where the one material is Mg ZK60 and the other material is Al 6061. Accordingly, there could be one material that has one grade and another that has another grade. For example, the material can be AA7075 and the other material can be AA6061. In accordance with example implementations, these billets can be part of the feedstock and the billets can be interlocked.
[0171] The extrusion feedstock materials may have a geometry that defines a ratio of the two materials when they are extruded as bound extrusions. The feedstock materials can be aligned along a longitudinal axis, and according to example implementations this can be the extrusion axis. The interlock of the billets can reside along a plane extending normally from the axis, and accordingly, the plane can intersect with both materials.
[0172] In order to improve the formability of magnesium sheet materials, the inventors believe that the grain sizes should be less than 5 microns and/or a weakened texture is desirable. It has been demonstrated that the novel Shear Assisted Processing and Extrusion (ShAPE) technology can not only attain the aforementioned microstructure but also help with the alignment of the basal planes (i.e. texture). This technology can also reduce the size and uniformly distribute the second phase particles, which are believed to impede the formability of sheets. In accordance with example implementations, extruded tubes of Mg can be slit open and rolled into the sheet. Extruded tubes of magnesium (ZK60 alloy) using the ShAPE process can be provided which can be 50 mm in diameter and 2 mm in wall thickness, or another diameter and wall thickness. These tubes can be slit open in a press and then rolled parallel to the extrusion axis, for example.
[0173] Referring next to
[0174] Referring next to
[0175] Referring next to
[0176] Referring next to
[0177] Referring next to
[0178] Accordingly, the methods of the present disclosure for preparing an extruded product from a solid billet can include providing an as-cast billet for extrusion. These as-cast billets are billets that have not been prepared to remove microfissures, convert phases, homogenize the billet to have a more uniform consistency throughout prior to extrusion. Billets with some amount of stress relief and phase conversion may also be used. To have a uniform consistency, convert phases, and removal of microfissures, the present disclosure provides applying a simultaneous rotational shear and axial extrusion force to the as-cast billet to plasticize the as-cast billet. During this performance of the method, the materials themselves are homogenized and/or plasticized, and the method can include extruding the plasticized as-cast billet with an extrusion die to form an extruded product. As such the metallurgical functions of stress relief, phase conversion, and homogenization may in part, or entirely, be accomplished by the ShAPE process.
[0179] As detailed herein, this can include the ShAPE technology described above. In accordance with an example implementation, the as-cast billet can be heated for approximately 17 hours between about 200° C. and 490° C. without a subsequent homogenization step prior to applying the simultaneous rotational shear and axial force. Additionally, where heat is applied, it can be applied in steps at predefined temperatures for predefined durations of time. For example, the temperature change between two of the steps can be about 260° C., or between two of the steps can be about 30° C. in temperature change, or other temperature differences combinations. Even when applying this heat for this time, the as-cast billet may not be homogenized prior to applying the simultaneous rotational shear and axial extrusion force to the as-cast billet. Accordingly, the as-cast billet can include intermetallic and/or distinct microstructures prior to the application of the rotational shear and axial extrusion force.
[0180] Referring to
[0181] With regard to
[0182] Referring next to
[0183] Referring next to
[0184] As described above, in a conventional linear force extrusion process, the billet itself is pre-heated in a furnace such as a jet billet log furnace to soften the billet to assist with the plasticization of the billet during extrusion. The present disclosure does not require such billet pre-heating in a furnace, and the only heating taking place occurs at one end of the billet as a result of the heat generated by the extrusion process, while a portion of the remainder of the billet remains at a lower temperature than the die/billet interface, for example.
[0185] Referring next to
[0186] Referring next to
[0187] Now it must be noted that typically in the prior art, a requirement of substantially more time is required for the artificial aging. In accordance with example implementations of the present disclosure, peak hardness can be obtained after artificially aging the extruded product for less than 10 hours and in general lower time than is standard and solution heat treat times and temperature below that specified in ASTM standards.
[0188] In effect, the ShAPE process is able to manufacture AA6063 in the T5 condition that has strength properties well above the ASTM and ASM standards for AA6063 in the T5 condition. Strength properties of AA6063 made by ShAPE in the T5 condition exceed the ASTM strength values for AA6063 in the T6 condition and approach the ASM strength properties of AA6063 in the T6 condition. Accordingly, excellent properties are obtained without the need for solution heat treating and quenching when extruding with ShAPE.
[0189] Additionally, these methods can be performed on any number of materials, but these example specific materials are AA6063 materials and near T6 properties can be achieved using the T5 conditions. As indicated in this specification, a range of materials can be utilized for these processes and include magnesium, aluminum, and all others listed herein.
[0190] Referring next to
[0191] As shown, the ShAPE extruded product can perform as well with lower temperature and time. As shown in
[0192] Referring to
[0193] Referring next to
[0194] Referring next to
[0195] Referring next to
[0196] While the largest applications of aluminum alloys is as cast or wrought articles, the powder metallurgy (PM) route has recently been utilized to produce net- or near-net-shape parts. This route is economically competitive for relatively small parts which would otherwise require extensive machining if fabricated from a bulk alloy. Additionally, aluminum PM benefits from more homogenous microstructures than wrought articles, and unique chemistries realized by rapid solidification or mechanical alloying. However, the conventional press-and-sinter approach presents great difficulty for aluminum alloys due to a tenacious oxide layer preventing full powder bonding, resulting in comparatively low strength and ductility. Other more complicated powder densification processes, which typically require multiple steps (canning, degassing, compaction, and extrusion or forging), break the powder oxide layers by severe deformation, thus resulting in near-theoretical density and good mechanical properties.
[0197] Referring next to
[0198] The stock material extruded using ShAPE can include powder material, casting material, and/or flake, powder, or scrap material. The material can be a solid billet or mixture of solid billets. The solid material can include one or more of the materials listed herein.
[0199] The extruded material can have a hardness of at least 155 HV after 3 hours of aging. Additionally, the extruded material may be solution heated and then aged. However, the aging of the extruded material after solution heating is performed for less than 3 hrs.
[0200] Powder metallurgy (PM) of high strength aluminum (Al) alloys typically requires multiple process steps prior to extrusion. In general, compacting powder into a densified billet or canning powder in a sealed container are the primary methods used to ready material for PM extrusion and have endured as the most widely utilized approaches for high strength Al alloys. For powder canning, typical steps include loading powder into a can, degassing, sealing the can, and heating. For powder compaction, typical steps include degassing, hot or cold isostatic pressing, and heating the densified billet. Eliminating any of these steps could make PM more cost effective. The compaction and canning processes have been researched extensively for high strength PM Al alloys.
[0201] Utilizing the apparatus and/or methods of the present disclosure, frictional heating of billet material in substantially powder form (most, if not all of the billet material is in powder form) can be localized to the die face, and spiral grooves, or a flat face without grooves, draw billet material towards the hollow center of the die utilizing (ShAPE). As the powdered billet is consolidated by compressive and shear forces within the deforming material (plasticizing) and frictional heating at the die face and within the deforming material, solid material is extruded. In accordance with at least some embodiments of the disclosure, low extrusion forces are required compared to conventional extrusion. Additionally, by directly creating solid extrudate from loose powder, many of the complicated processing steps necessary for the other methods are eliminated, presenting a scalable method to produce high strength aluminum alloys. These methods can be utilized successfully to extrude magnesium flakes and/or a gas-atomized aluminum alloy powder containing 12.4 wt. % transition metal. The ShAPE process can extrude hollow tubular profiles directly from powder which is not readily possible with conventional powder metallurgy extrusion.
TABLE-US-00004 TABLE 4 Mechanical properties of extruded powder materials (ShAPE and non-ShAPE) Temperature Yield Strength Method (° C.) (MPa) Elongation (%) PM Extrusion Ambient 375-405 4.5-9.0 ShAPE Extrusion Ambient 380 ± 13 15.74 ± 2.5 ShAPE Extrusion 200/300 314/238 9.5/9.4 Testing performed per ASTM B557
[0202] As shown above in Table 4, the ShAPE materials demonstrated superior mechanical properties when compared to non-ShAPE extruded materials. In accordance with example implementations and with reference to
[0203] Accordingly, methods for preparing an extruded material by shear assisted processing and extrusion from a powder billet are provided. The method can include providing a billet of material in substantially powder form. This powder can be considered a loose powder (unpacked, or noncompacted). The powder can include one or more of Al, Mg, Fe, Si, and/or Zr. The billet material can have a maximum particle size of 100 um, but particle sizes greater than 100 um can be utilized as well. The powder can include an oxide or powder component
[0204] The method can include applying both axial and rotational pressure to the material to deform at least some of the material, and extruding the material to form an extruded material as described herein. Particularly, an extrusion die defining spiral grooves can be used.
[0205] The extruded material include an alloy and/or can have a tensile strength from about 220 MPa to about 360 MPa. Additionally, the extruded material can have a hollow profiles (i.e. hollow tubes that are circular, non-circular, or even have multiple hollow zones), as shown and described herein.
[0206] The ShAPE process can be used to prepare product materials from Al—Mg—Zr powder. The application of ShAPE to high performance aluminum powders can eliminate process steps used during PM extrusion. Specifically, canning, degassing, sealing, charge pre-heating, cold/hot isostatic pressing, extrusion, and decanning used in PM extrusion can be eliminated and replaced by container filling, compaction, and subsequent ShAPE processing. Process parameters (rpm, feed rate, forge force and temperature) can provide for the extrusion of fully consolidated extrudates (extruded material).
[0207] High performance bulk material from aluminum powders that include alloys can be fabricated. By combining the versatility of the ShAPE process and the far-from-equilibrium microstructures of the gas-atomized Al—Mg—Zr Addalloy powders, PM parts can be designed and developed for mass applications from precipitation-strengthened aluminum alloys with outstanding coarsening resistance that have high thermal stability.
[0208] ShAPE can increase extrusion speeds, for example in the preparation of aluminum alloys. The ShAPE process parameters and tooling enable fast extrusion speed for aluminum alloys, which traditionally have been difficult to extrude. Conventional extrusion speed(s) for aluminum alloys in series 2XXX and 7XXX are generally 1-2 meters/minute.
[0209] The ShAPE processes and methods described herein increase extrusion speed(s), which can, in some examples, reduce the cost of 7XXX (7 series), 2XXX (2 series), and other alloy extrusions, aluminum and non-aluminum. The ShAPE process has been advanced for fabrication of AA7075 extrusions at extremely high speed(s) compared to conventional extrusion. For example, a speed of 7.4 meters/minute has been achieved with mechanical properties equal to, or in excess of, properties achieved from slow speed conventional extrusion (i.e., the ASTM B241 standard and/or consistent with the typical values in the ASM handbook).
[0210] Accordingly, methods for preparing extruded material by shear assisted processing and extrusion are provided that can include applying both axial and rotational pressure to stock material to form an extruded material at a rate between 2 and 13 m/min in some implementations, 3 and 13 m/min in others, and 7 and 13 m/min in still others. As described herein, the stock material or billet material can be defined by castings, or chunks of material randomly aligned. This material can be sourced as recycled material and can include Al and/or any of the materials listed herein.
[0211] The methods can include maintaining a temperature of the die face below 420° C.
[0212] The extruded material has a tensile strength between 500 and 580 MPa, a yield strength between 420 and 500 MPa, and/or an elongation % between 12 and 18.
[0213] Homogenized AA 7075 castings were machined into billets having an inner diameter (ID) of 10.1 mm, outer diameter (OD) of 31.8 mm, a length of 100 mm. Extrusions were fabricated using a ShAPE machine manufactured by BOND Technologies capable of 900 kN axial force and torque of 3000 Nm at 500 rpm. The linear speed of tailstock is 0.36 meters/min which gives an extrusion speed of 7.4 meters/min for the extrusion ratio of 20.6, for example. Speeds up to 12.2 meters per minute and beyond have been achieved for 7XXX and 2XXX. In conventional extrusion, a high peak force is required at the beginning of direct and indirect extrusion processes, which is known as the breakthrough force. This is because a given pressure is required to start deforming the material, which drops to a lower pressure once the material starts flowing. This is not desirable because the peak breakthrough force dictates the required capacity of the extrusion press. Lower force means a smaller extrusion press and lower operating cost. The origin of the work is that the research team was trying to keep the force as low as possible to get the highest speed extrusion possible out of the research scale ShAPE machine which is limited to 900 kN.
[0214] Breakthrough force was eliminated by ramping ram speed (generally ramping up) and rotational speed of the die (generally ramping down). In doing so, these parameters are balanced to generate heat sufficient to locally soften the billet material ahead of the die. Because the material that the die encounters is always soft from the very beginning of the stroke, the force gently rises to steady state for shear extrusion. This is in contrast to conventional extrusion where force rises quickly to a peak force as the die encounters cooler material and then reduces to lower the steady state value.
[0215] As can be seen in
[0216] Table 5 below provides a list of example alloys and a rating of extrusion difficulty.
TABLE-US-00005 TABLE 5 Alloy Difficulty 1000 77 1100 86 6063 100 3005 106 3003 112 6105 134 4047 128 3105 126 6061 151 5005 154 7004 157 2011 171 3004 180 6082 197 2014 202 5052 229 5056 232 2024 247 5054 265 7150 269 7050 280 5083 281 5182 293 5456 300 7075 316
[0217] In compliance with the statute, embodiments of the invention have been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the entire invention is not limited to the specific features and/or embodiments shown and/or described, since the disclosed embodiments comprise forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.