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US20060283529A1 - Apparatus and Method of Producing Net-Shaped Components from Alloy Sheets - Google Patents

Apparatus and Method of Producing Net-Shaped Components from Alloy Sheets Download PDF

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US20060283529A1
US20060283529A1 US11/425,067 US42506706A US2006283529A1 US 20060283529 A1 US20060283529 A1 US 20060283529A1 US 42506706 A US42506706 A US 42506706A US 2006283529 A1 US2006283529 A1 US 2006283529A1
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precursor
plastic deformation
work piece
strain
grain
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Amit Ghosh
Raymond Decker
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Priority to US11/679,239 priority patent/US20080000557A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/007—Semi-solid pressure die casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D13/00—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form
    • B21D13/02—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form by pressing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D13/00—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form
    • B21D13/04—Corrugating sheet metal, rods or profiles; Bending sheet metal, rods or profiles into wave form by rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/021—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips involving a particular fabrication or treatment of ingot or slab
    • C21D8/0215—Rapid solidification; Thin strip casting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0242—Flattening; Dressing; Flexing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/12—Making non-ferrous alloys by processing in a semi-solid state, e.g. holding the alloy in the solid-liquid phase
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals

Definitions

  • the present invention relates to producing net shaped components of increased strength. More particularly, the invention relates to producing sheet components, having micrometer sized grain structures, that can be subsequently used in the production of net shaped sheet components of increased strength.
  • Mg alloy development has been inhibited by certain barriers. While wrought magnesium has the potential for making thinner structures, anisotropy in mechanical properties limits the applications of Mg alloys and their wrought products.
  • the strength of Mg alloys is rather low in certain directions in comparison to most widely used structural materials, such as steels and precipitation-hardened aluminum (Al) alloys.
  • yield strength can be only 85 MPa in basal textured Mg alloy; AZ31 B Mg alloy sheet in the H24 temper could have a high-value normal anisotropy parameter (R) of 3.2 in the transverse direction.
  • R normal anisotropy parameter
  • a high value of normal anisotropy in sheet is helpful for deep drawing, but may not be suitable for other applications, particularly if in-plane strength is also anisotropic. In fact, this base element has not been a friendly host for extensive alloy strengthening.
  • alloying elements that improve corrosion resistance and castability such as Al
  • Hexagonal close packed (HCP) structured Mg alloys have low symmetry of slip systems that contributes to high anisotropy of mechanical properties.
  • “basal a” slip ⁇ 0001 ⁇ 1120 is predominant, while “prism a” and c+a slip are difficult because of their significantly high critical resolved shear stresses (CRSS), which are reported in regions of high stress concentration such as grain boundaries and twin interfaces.
  • CRSS critical resolved shear stresses
  • Deformation twinning is often observed in polycrystalline Mg to compensate for the insufficiency of independent slip systems.
  • the most common twinning modes are ⁇ 1012 ⁇ and ⁇ 1011 ⁇ twinning which accommodate the c-axis extension and contraction, respectively.
  • Mg alloy Another means to strengthen Mg alloy, relative to Al and steel, is by grain refinement.
  • strength is proportional to d ⁇ 1/2 , where d ⁇ grain size.
  • conventional Mg alloy sheets and extrusions have a grain size in the range of 10 to 90 ⁇ m, reducing the grain size to about 1 ⁇ m or less (thus nanostructured and herein referred to as an “ultrafine grain size”) offers a striking opportunity to escalate the strength/density of Mg to levels above Al and steel.
  • An ultrafine grain size could enable superplastic deformation to be carried out at lower temperatures and higher strain rates.
  • grain refinement strengthens many polycrystalline metals. This is true for cubic structured metals such as Al, copper (Cu) and iron (Fe).
  • HCP metals such as Mg alloys, grain refinement may also cause texture variation, and inadequate strengthening in certain directions.
  • Superplasticity is an attribute associated with fine-grained alloys. This plastic-type property is utilized commercially in automobiles and aircrafts to form complex net shapes in titanium (Ti) and Al. To date, Mg alloys have not enjoyed this advantageous processing in commerce. First, Mg alloy castings do not have the prerequisite grain boundary crystal structure and, secondly, wrought Mg sheets have been too coarse grained and/or too textured for superplastic forming.
  • nano-size strengthening phases of about 100 nanometers are desirable within the grains. This is another strengthening mechanism, heretofore not available in weakly alloyed AZ31 sheets.
  • construction and assembly of such a microstructure for bulk structural parts, ab-initio from nano-powders, is a very costly and laborious.
  • safety and health concerns for handling such fine particles in the workplace It seems to be safer and more practical to generate such nano-strengthening particles in-situ during processing of the already assembled bulk component.
  • Grain size has a major effect on the formability of Mg alloy sheets.
  • Commercial wrought Mg alloy sheet is available only in low strength AZ31 alloy. It is fabricated from direct cast (DC) slabs (0.3 m thick) having a grain size of 200-1000 ⁇ m.
  • Twin roll casting (TRC) a prototype process, is offered at 2 to 5 mm thicknesses with 60 to 2000 ⁇ m grain sizes and is currently only capable of 432 mm wide sheets. Fabrication from DC or TRC promotes strong texture because of the limited slip systems and twinning occurring in Mg alloys with such large grain sizes. Extrusions formed from such a base source are also textured to the extent that strength is 50% and toughness is 72% in one direction as compared to the cross direction.
  • the grain boundary structure in conventionally prepared Mg alloy is not favorable to complex deformation without premature fracture, unless an elevated forming temperature is used.
  • the pressing and deep drawing of 3-D shapes is limited by the texture and the inherent non-uniform deformation that results from twinning.
  • twinning in some directions of the sheet causes increased elongation during tensile testing, twinning is an impediment to the formation of complex parts due to the anisotropy it produces in coarse grain Mg alloy, resulting in anomalies in work hardening and non-uniform deformation.
  • the modeling of forming processes and performance in the dies is not reliable with such non-uniformity in structure.
  • the coarse surface finish of present coarse grain Mg alloys poses a challenge to their acceptance as automotive sheet parts.
  • the inventors have discovered a practical new process and apparatus to generate inexpensive ultra fine grain structured sheets, where grain sizes of less than or equal to about 2 ⁇ m are achieved, which can be subsequently deformed via superplastic forming processes to form net shaped, sheet formed articles.
  • Various metals and alloys can be employed with the present invention, including, but not limited to, Mg, Al, zinc (Zn), nickel (Ni), copper (Cu), ⁇ / ⁇ Ti, steels, duplex ⁇ / ⁇ stainless steels, ⁇ / ⁇ steels, ⁇ /martensite Maraging steels and metal/ceramic particle composites.
  • the present process involves the sine-wave deformation processing (SWP) of fine grain structured sheets initially formed from various rapid solidification molding methods that can produce an ultra fine grain precursor, including injection molding and variations on injection molding, extrusion molding and twin roll casting. Thereafter, the final net shaping of parts can be accomplished by superplastic forming, drawing or stamping, etc.
  • SWP sine-wave deformation processing
  • the present invention provides for the initial formation of a fine grained precursor having a grain size of less than about 10 ⁇ m. Thereafter, the fine grained precursor is subjected to SWP, which breaks down the microstructure of the precursor and produces new grain boundaries.
  • the resulting sheet has an ultra fine grain structure lending itself to final net shaping by superplastic forming processes.
  • the present invention is a method of forming a sheet material having a refined grained structure, the method comprising the steps of: providing a metal material; molding and rapidly solidifying the metal alloy to form a fine grain precursor; and imparting plastic deformation to the fine grain precursor by a combination of alternating tensile strain and compressive strain to form an ultra fine grain structured sheet form.
  • the step of molding and solidifying develops a mutliphased microstructure in the fine grained precursor.
  • the multiphased microstructure includes pinning particles that minimize grain growth.
  • the step of imparting plastic deformation includes the step of storing dislocations in the microstructure.
  • step of imparting plastic deformation includes the step of causing the formation of new grain boundaries having high misorientation suitable for warm forming or superplastic forming.
  • Still another aspect is that the molding step and the imparting plastic deformation step are performed in an integrated apparatus.
  • a further aspect is that the molding step and the imparting plastic deformation step are performed by separate machines.
  • the molding step includes semisolid metal injection molding of the metal material.
  • the molding step includes one of extruding of the metal material and twin roll casting of the metal material.
  • the imparting plastic deformation step includes corrugating the precursor in a first direction and subsequently corrugating the precursor in a second direction.
  • the second direction is orthogonal to the first direction.
  • Still another aspect is that the second direction is aligned with the first direction.
  • a further aspect is that the imparting plastic deformation step further includes the step of flattening the precursor.
  • the flattening step is performed after at least one of the steps of corrugating the precursor in the first direction and the second direction.
  • the imparting plastic deformation step further includes the step of corrugating in a third direction and a fourth direction.
  • a second flattening step is performed after at least one of the third and fourth corrugating steps.
  • the step of net shaping the nano-sized grain structure sheet after the step of imparting plastic deformation, the step of net shaping the nano-sized grain structure sheet.
  • the invention further includes the step of heat treating the net shaped part to impart creep resistance to the net shaped part.
  • the step of net shaping includes one of stamping, drawing, deep drawing and superplastic forming.
  • the step of net shaping forms an automotive component.
  • the invention includes an apparatus for performing the above mentioned method.
  • the invention includes an article formed by the above mentioned method.
  • the invention further includes the step of providing the sheet form with a thickness being less than that of the precursor.
  • the metal material is a metal alloy.
  • the metal material is a magnesium alloy.
  • the metal material is one selected from the group of aluminum alloy, zinc alloy, nickel alloys, copper alloy, ⁇ / ⁇ titanium alloy, steels, duplex ⁇ / ⁇ stainless steels, ⁇ / ⁇ steels, ⁇ /martensite Maraging steels and metal/ceramic particle composites.
  • the step of imparting plastic deformation includes die pressing of the fine grain precursor.
  • the step of imparting plastic deformation includes rolling the fine grain precursor.
  • the sheet form is provided having a grain structure of less than about 2 micrometers.
  • the sheet form is provided having a grain structure of less than about 1 micrometer.
  • the step of imparting plastic deformation is performed while the precursor is heated above ambient.
  • the step of imparting plastic deformation imparts tensile strain and compressive strain in a strain direction.
  • the step of imparting plastic deformation is performed by passing the precursor in a first direction between at least one pair of deforming members having corrugated surfaces, and wherein the first direction is orthogonal to the strain direction.
  • the compressive strain is imparted at least in part by flattening the work piece while constraining lengthening of the work piece in the strain direction.
  • constraining lengthening of the work piece in the strain direction is done so as to achieve one of decreasing, increasing or preserving the thickness of the precursor in the sheet form
  • the invention is an apparatus for refining grain structure and producing ultra-fine grained metal material sheets, the apparatus comprising: a receptacle having an inlet, a discharge outlet remote from the inlet, and a chamber defined between the inlet and the discharge outlet; a feeder coupled with the inlet, the feeder configured to introduce an metal material into the chamber via the inlet; a heating device for transferring heat to the metal material located within the chamber such that the metal material is at a temperature above its solidus temperature; discharge means for discharging the metal material from the receptacle through the discharge outlet; forming means for forming and rapidly solidifying the discharged metal material into a fine grained precursor; plastic deformation means for imparting strain into the precursor article and deforming the precursor article into a corrugated work piece, the plastic deformation means including a pair of opposing forming members having protrusions formed on a surface thereof, the protrusions of one forming member being offset from the protrusions of the opposing forming member; and flattening means
  • the opposed forming members are pressing dies or rolls.
  • the plastic deformation means includes means for imparting tensile strain and compressive strain into the precursor article.
  • the plastic deformation means includes means for imparting first corrugations oriented in a first direction into the precursor article and subsequently imparting second corrugations oriented in a second direction.
  • the second direction is orthogonal to the first direction.
  • the second direction is aligned with the first direction.
  • the plastic deformation means is configured to impart third corrugations and fourth corrugations into the work piece.
  • the third and fourth corrugations are respectively oriented in the direction of the first and second corrugations.
  • the third and fourth corrugations are out of phase with the first and second corrugations.
  • the third and fourth corrugations are respectively 180 degrees out of phase with the first and second corrugations.
  • the invention further includes net shaping means for shaping the sheet form of the metal material into a net-shaped article.
  • the shaping means is one of a drawing press and a superplastic forming machine.
  • the receptacle, feeder, heating means, discharge means and forming means are part of an injection molding machine.
  • the receptacle, feeder, heating means, discharge means and forming means are part of a semi-solid metal injection molding machine.
  • the invention is a method of forming a sheet material having a refined grained structure, the method comprising the steps of: providing a metal material; molding and rapidly solidifying the metal alloy to form a fine grain precursor defining a line length; initially increasing the line length of the precursor to form a work piece; decreasing the line length of the work piece and then increasing the line length of the work piece; and flattening the work piece to form an ultra fine grain structured sheet form.
  • the step of flattening the work piece is performed before the decreasing and increasing step and then again after the decreasing and increasing step.
  • the step of flattening the work piece is performed after the decreasing and increasing step.
  • the initially increasing step introduces strain into the work piece in a first direction.
  • the decreasing and increasing step introduces strain into the work piece in a second direction.
  • the second direction is orthogonal to the first direction.
  • the second direction is generally aligned with the first direction.
  • the plastic deformation means imparts tensile and compressive strain in a strain direction that is orthogonal to a direction through which the work piece is passed through the plastic deformation means.
  • the flattening means imparts, at least in part, compressive strain to the work piece.
  • the flattening means includes features to control lengthening of the workpiece in the strain direction whereby the thickness of the sheet form may be controlled so as to be increased, decreased or the same as the thickness of the precursor.
  • FIG. 1 is schematic illustration of a manufacturing cell embodying the principles of the present invention
  • FIG. 2A is a perspective view of the longitudinal roll dies shown in FIG. 1 and which may be utilized with the present invention
  • FIG. 2B is a perspective view of the transverse roll dies seen in FIG. 1 which may be used with the present invention
  • FIG. 2C is perspective view of flattening roll dies as seen in FIG. 1 and used in connection with the present invention
  • FIG. 2D is perspective view of a pair of pressing dies that may be utilized as an alternative to roll dies in accordance another embodiment of the present invention.
  • FIG. 3 is a flowchart of one possible process in accordance with the present invention.
  • FIG. 4 is a flowchart of another possible process incorporating the principles of the present invention.
  • FIG. 5 is a diagrammatic illustration of the present invention incorporating an extrusion device
  • FIG. 6 is a schematic illustration of a twin roll casting device incorporated with the present invention.
  • FIG. 7 is a graphical comparison of the effect of grain size (d) on hardness (Hr) for SWP AZ91D and AZ31B;
  • FIG. 8 is a representation of the results of a superplastic bulge test (processed at 280° C. and 200 psi) as a function of initial grain size
  • FIGS. 9A, 9B , 9 C and 9 D are schematic illustrations of a precursor undergoing SWP according to another embodiment of the present invention.
  • a fine grained precursor is formed by the injection molding of metal, such as by the ThixomoldingTM process of Thixomat, Inc., Ann Arbor, Mich.
  • melt temperatures can be lowered to near liquidus, some 80 to 100° C. lower than in DC or TRC. These lower temperatures assist in faster cooling to nucleate finer grains upon solidification.
  • ThixomoldedTM Mg alloys are isotropic with 4 to 5 ⁇ m grain size a phase.
  • Suitable sheet bar would be readily molded in existing commercial Thixomolding machines, of sizes up to 1000 tons, with sheet dimensions of 20 ⁇ 400 ⁇ 400 mm.
  • Table 1 presents various production methods for a precursor work piece, such as sheet bar, as well as for a range of grain sizes resulting from that production method including the method of the present invention.
  • FIG. 1 this figure schematically illustrates an apparatus, generally designated at 8 , embodying the principles of the present invention.
  • the apparatus 8 includes a molding machine 10 for the metal injection molding of sheet bar.
  • the construction of the molding machine 10 is, in some respects, similar to that of a plastic injection molding machine.
  • the machine 10 is fed with feedstock 11 via a hopper 12 into a heated, reciprocating screw injection system 14 which maintains the feedstock under a protective atmosphere such as argon. More particularly, the feedstock is received into a barrel 15 via an inlet 16 located at one end of the barrel 15 . Within the barrel 15 , the feedstock is moved forward by the rotating motion of a screw 18 .
  • the feedstock As the feedstock is moved forward by the screw 18 , it is also heated by heaters 20 (which may be a resistance, induction or other type of heater) while being stirred and sheared by the action of the screw 18 . This heating and shearing is done to bring the feedstock material into a injectable state.
  • This injectable material passes through a non-return valve 22 and into an accumulation zone 24 , located within the barrel 15 beyond the forward end of the screw 18 .
  • the injection portion of the cycle is initiated by advancing the screw 18 with a hydraulic or other actuator 25 .
  • Advancement of the screw 18 causes the material in the accumulation chamber 24 to be ejected through a nozzle 26 into a mold 28 filling the mold cavity defined thereby and forming a precursor work piece such as sheet bar 30 .
  • This initial formation of the precursor allows developing of a multiphase microstructure with pinning particles or phases to pin grain boundaries to minimize grain growth.
  • the metallurgical process of the machine 10 results in the processing of the particulate feedstock into a solid plus liquid phase prior to its injection into the mold 28 .
  • Various versions of this basic process are known and two such versions are disclosed in U.S. Pat. Nos. 4,694,881 and 4,694,882, which are herein incorporated by reference.
  • the process generally involves the shearing of the semisolid metal so as to inhibit the growth of dendritic solids and to produce non-dendritic solids within a slurry having improved molding characteristics which result, in part, from its thixotropic properties.
  • a semisolid non-dendritic material exhibits a viscosity that is proportional to the applied shear rate and which is lower than that of the same alloy when in a dendritic state).
  • Variations on this process of forming the sheet bar 30 may include providing the alloy material initially in a form other than a particulate; heating the alloy material to an all liquid phase and subsequently cooling into the solid plus liquid phase; utilize twin screws for processing the alloy; employing separate vessels for processing of the alloy and injecting of the alloy; utilizing gravity or other mechanisms to advance the alloy through the barrel to the accumulation zone; alternate feeding mechanism, including electromagnetic; and other variations on the process.
  • metallurgical process of the machine 10 results in the processing of the particulate feedstock into an all liquid phase that is injected into the mold 28 and rapidly solidified.
  • SWP involves the imparting of plastic deformation by a combination of alternating tensile and compressive strains or deformations. This second step permits storage of dislocations within the microstructure, which leads to the formation of new grain boundaries with high misorientation suitable for subsequent warm forming or superplastic forming.
  • the precursor is subjected repeated shaping of the material between a pair of corresponding members having corrugated or sine-wave shaped forming surfaces.
  • the shape of the forming surfaces impart large strain, breakdown the cast microstructure and produce new grain boundaries in the precursor.
  • sheet bar 30 initially formed so as to have a fine grain structure of 10 ⁇ m or less, this precursor work piece is then shaped, with or without lateral constraint, between two members having corresponding corrugated forming surfaces, in what is essentially a plane-strain stretch-bend operation.
  • the work piece is again shaped, During this second shaping, however, the corrugations are preferably, but not necessarity, oriented in a direction different from the corrugations of the first shaping. An orthogonal orientation for the second shaping is believed to produce the best end results.
  • the two shaping steps are then repeated with the corrugations in these third and fourth steps being the inverse of those seen in the first two shaping steps.
  • inverse what is meant is that the ridges and valleys of the third corrugation are reversed or out of phase from the ridges and grooves of the first corrugations.
  • these subsequent shaping cause a reverse deformation (pushing in the opposite direction) of ridges resulting after the first two shapings.
  • the work piece is preferably flattened to remove any waviness to the shape. As further discussed below, the work piece may alternatively be flattened between each shaping step or after the first two shaping steps.
  • the alternating tensile and compressive deformations are imparted by creating a general sine wave shape in the precursor.
  • This shaping increases the line length (the length of the centerline of the precursor).
  • a reverse sine wave shaping of the work piece results in the line length initially being shortened and then again lengthened as the raised ridges of the shape are converted in recessed valleys. When undergoing flattening, the line length is thus shortened. Accordingly, increasing the line length introduces tensile strain into the work piece and reducing the line length introduces compressive strain.
  • SWP is conducted at a warm temperature and the deformation temperature of the material is progressively lowered after each pass, for example, starting at 250° C. and decreasing to 170° C. for the final flattening step.
  • This can be achieved in several ways, including providing heated shaping members or rolls, as described below.
  • the strain in the mid-plan has gone from tension to compression to tension again in both the 0° and 90° directions.
  • all parts of the sheet bar material are deformed in a manner of “kneading”, by incorporating reversed plane strain bending and plane strain stretching in two orthogonal directions of the plate.
  • the repeated deformation by the process causes accumulation of large plastic strain and breaks up the original grain structure within the work piece. Grain refinement occurs initially heterogeneously, but eventually homogeneously, over a large area. While four shapings are discussed in one of the preferred embodiments, more or less shapings may be possible to achieve the desired results.
  • SWP can be achieved by passing the sheet bar 30 successively through a series of rolls or by pressing the sheet bar successively between a pair of opposing pressing dies, either of which may be heated. Also, SWP may be performed separately (at a remote location) from the formation of the sheet bar 30 or may be integrated directly into a processing cell whereby the apparatus 8 is provided with a transfer mechanism (which may be any known variety and which is represented by line 29 ) to transfer the sheet bar 30 from the mold 28 to a rolling or pressing mill 31 . As seen in FIG. 1 , the apparatus 8 includes a rolling mill 31 , having a series of roll sets, integrated with the molding machine 10 . The rolls of the roll sets may be impressed toward each other by backup rolls 33 (shown in phantom) as is commonly known.
  • the sheet bar is passed through a first set 32 of opposed corrugated rolls 34 .
  • the surfaces of the rolls 34 are each provided with corrugations 36 extending circumferentially about the rolls 34 .
  • the corrugations 36 of each rolls 34 generally correspond with respect to one another such that a ridge on one of the rolls 34 is received in a valley of the opposing rolls 34 .
  • a lengthwise corrugation, parallel to the direction of travel of the sheet bar 30 is imparted into the sheet bar 30 . This results in a sine wave shape being imparted to the work piece that is oriented in a direction orthogonal to the direction in which the work piece is passed through the rolling mill 31 .
  • the induced strains, tensile and thereafter compressive will be generally in the direction of the sine wave shape itself.
  • the lower roll 34 in FIG. 1 may be provided with raised lands 38 on the opposing ends of the roll 34 .
  • the lateral most corrugations of the upper roll 34 fit within and extend below the uppermost surface of the lands 38 .
  • the sheet bar 30 is constrained from expanding laterally beyond the lands 38 of the rolls 34 .
  • These rollers, 34 are separately illustrated in FIG. 2A apart from the subsequent rollers. Alternately, lateral expansion may be unconstrained.
  • the worked sheet bar or work piece is passed to a second set 40 of rolls 42 .
  • the work piece Upon encountering this second set 40 of rolls 42 , the work piece encounters corrugations 44 that are oriented orthogonally, 90 degrees from the corrugations 36 of the first set 32 of rolls 34 .
  • the corrugations 44 are oriented axially with respect to the rolls 42 and transverse with regard to the direction of travel of the sheet bar 30 .
  • the corrugations 44 of the second set 40 of rolls 42 are provided such that the ridge of a corrugation on the upper roll 42 is received within the valley of a corrugation 44 of the lower roll 42 .
  • Raised lands 46 may be formed on the lower roll 42 so as to define constraints and prevent lateral lengthening/expansion of the work piece as it is passed through the second set 40 of rolls 42 .
  • the rollers 42 of the second set 40 are separately illustrated in FIG. 2B and could alternatively be provided such that lateral expansion is unconstrained.
  • the worked sheet bar is passed in the illustrated rolling mill 31 between a third set 48 of rolls 50 designed to flatten the worked sheet bar.
  • the rolls 50 are provided with smooth surfaces 52 that engage and compress the worked sheet bar as it passes between the rolls 50 .
  • the lower roll 50 of the third set 48 of rollers includes raised lands 54 to constrain and inhibit lateral lengthening/expansion of the worked sheet bar as it passes between the rolls 50 .
  • the thickness of the resulting sheetstock material 78 can be controlled so as to be decreased, increased or the same as the original thickness of the sheet bar 30 , all the while continuing to accumulate plastic deformation to the sheetstock material 78 .
  • the rolls 50 of the third set 48 are separately illustrated in FIG. 2C .
  • the work piece may again be subjected to corrugation and the process of passing the work piece through the three sets of rollers is repeated, as suggested by dashed line 56 .
  • pressing plates 58 may be used in place of the sets of rolls 32 , 40 , 48 .
  • the plates 58 are provided with cooperating corrugations 60 in which the ridge of one corrugation interfits with the valley of the opposing corrugation.
  • a raised perimeter or land 62 is provided about the periphery of one of the plates, herein the lower plate 60 , so as to laterally constrain the sheet bar 30 as it is pressed therebetween.
  • SWP occurs generally according to the process illustrated by the flowchart of FIG. 3 .
  • SWP starts at box 66 wherein a sheet bar 30 is received and subjected to corrugating in a lengthwise or parallel direction in box 68 .
  • the work piece undergoes transverse corrugation in box 70 and subsequently is flattened as indicated in box 72 .
  • the lengthwise and transverse corrugating of the work piece may be repeated as indicated by line 74 .
  • the work piece can undergo subsequent lengthwise and transverse corrugation prior to being flattened in box 72 .
  • box 72 flattening according to box 72 occurs prior to subsequent corrugation of the work piece.
  • the work piece is finally flattened in box 72 and flat sheetstock material 78 is outputted and the process ends in box 80 .
  • the transverse corrugation of box 70 can be replaced with an additional lengthwise corrugation, aligned with or off set from the initial lengthwise corrugation.
  • SWP Two alternative methods for SWP are illustrated by the flowchart of FIG. 4 .
  • SWP begins in box 82 where sheet bar 30 is transferred to the first set 32 of rolls 34 where it undergoes lengthwise corrugation in box 84 .
  • an additional set of rolls similar to the flat rolls 50 of the previously mentioned third set 48 are provided so as to flatten the work piece in box 86 .
  • the worked and flattened work piece is thereafter transferred to another set of rolls where transverse corrugation occurs in box 88 .
  • a set of rolls again flatten the work piece in box 90 .
  • the work piece is transferred back to the first set of rollers, according to line 92 , where lengthwise corrugation is again performed in box 84 .
  • the work piece then proceeds through flattening (box 86 ), transverse corrugation (box 88 ), flattening (box 90 ) and the formed flat sheetstock material 78 is produced at the end of SWP as indicated by box 94 .
  • FIGS. 9A-9D illustrate the concept of line lengthening and shortening, as well as lateral constraint, in another embodiment of the invention.
  • the precursor 30 undergoes plastic deformation in a set of non-constraining rolls 334 that are generally analogous to the rolls 34 of FIG. 1 .
  • the rolls 334 include mating or corresponding corrugations 336 that extend circumferentially around the rolls 334 .
  • a generally sine wave shape is imparted into the worked precursor (the work piece), generally orthogonally to the direction of rolling.
  • the rolls 334 are non-constraining, the work piece is lengthened along its centerline visa vi the sine wave shape.
  • An initial rolling or corrugating of the precursor 30 thus lengthens and imparts tensile strain to the work piece. Subsequently, as seen in FIG.
  • the work piece is at least partially flattened (imparting compressive strain) by the flat surfaces 352 of rolls 350 , which are generally analogous to the rolls 50 of FIG. 1 .
  • Rolls 350 laterally constrain, via lands 354 , the work piece as it is flattened and as such the line length is reduced during flattening.
  • FIG. 9C the work piece under goes a corrugation between another set of rolls 360 having corrugations 362 that are circumferential or parallel to the rolling direction of the rolls 360 .
  • This corrugation is a reverse corrugation, however, in that the corrugations 362 of this set of rolls 360 are reversed from corrugations of corrugated roll 334 .
  • the peaks and valleys of these rolls are generally oppositely oriented relative to those of the prior corrugated rolls 332 .
  • this set of corrugated rolls 362 will first compress and then stretch the work piece as previously described elsewhere in this specification, resulting in the overall lengthening of the line length of the work piece. Again, the corrugation may be done without lateral constraint by the rolls 362 . Finally, as seen in FIG. 9D , the work piece is compressed and the sine wave shape completely flatten between a set of rolls 372 .
  • the work piece may undergo any number of corrugations cycles (where the strain is aligned, orthogonal to or otherwise oriented with respect to the previously induced strain), or other processing steps, imparting tensile and compressive strains so as to accumulate deformation in the work piece.)
  • the work piece is laterally constrained by lands 374 so that the final sheet form 378 is outputted for further processing.
  • FIGS. 9A-9D are illustrated in a side by side positioning.
  • the construction is representative of a reverse rolling mill.
  • the work piece is provided through one roll in one longitudinal direction and through a subsequent roll in a generally reversed longitudinal direction.
  • Reverse rolling mills themselves are well known in the art and further elaboration on the construction is therefore warranted herein.
  • FIGS. 5 and 6 schematically illustrate two additional manufacturing schemes wherein the injection molding machine 10 of the first embodiment is alternately replaced with an extrusion machine 110 (in FIG. 5 ) and a twin roll casting machine 210 (in FIG. 6 ).
  • the extrusion machine 110 includes a barrel 112 within which is located a screw 114 .
  • material is extruded from the extrusion machine 110 and rapidly solidified between a pair of molds 116 such that a continuous sheet of solid material is transferred from the extrusion machine to the rolling mill 31 .
  • the rolling mill 31 illustrated in FIG. 5 is similar to the rolling mill 31 discussed in connection with the prior embodiment. Accordingly, reference is hereby made thereto and further discussion is not required.
  • the twin roll casting machine 210 includes a pair of counter-rotating rolls 212 which receive the processed material 214 from a processing vessel 216 . Between the rolls 212 , the material 214 is rapidly solidified into a precursor sheet form 218 of a first thickness 220 .
  • the twin roll casting machine 210 By precisely controlling the twin roll casting machine 210 , it is anticipated that the fine grain microstructure required according to the present invention can be achieved. Accordingly, by transferring the precursor material 214 to a rolling mill 231 similar to that previously described, the material 214 can be reduced to a final sheet form 222 having the desired reduced thickness 224 . Since the rolling mill 31 of FIG. 6 is substantially of the same construction as that previously described in connection with FIG. 1 , reference thereto is herein made.
  • the above described SWP process can reduce the thickness of the sheet to about 2 mm, wherein the final sheet dimensions could be 1250 ⁇ 1250 mm. With thinner starting materials, such as 6.35 mm hot rolled plate, it is anticipated that the thickness can be reduced to about 1 mm.
  • the SWP process can produce a sheet maintain the original starting thickness of the precursor or can actually produce a thickened sheet. The latter is achieved by further constraining lateral expansion of work piece, after the work piece has been shortened via a corrugating step, to a dimension that is less than the starting dimension of the precursor.
  • the rate of production in one machine is anticipated to be about 1 sheet bar per 20 seconds.
  • the as-molded grain size and a content of an injection molded metal sheet bar is a favorable starting point to attaining sub-micron grain size and low-anisotropy in the subsequently SWP sheet.
  • SWP with its vigorous thermomechanical working, subdivides intermetallic particles into nano-sizes, and, probably, encourages partial solution and more homogeneous reprecipitation of fine arrays within the grains.
  • Some sub-divided residual ⁇ phase could serve to pin grain boundaries during dynamic recrystallization and heat treatment.
  • the subdividing of this inherently coarse ⁇ phase is beneficial to the ductility of Mg alloys.
  • the same role is anticipated as being possible with two phase alloys, such as ⁇ / ⁇ Ti, ⁇ / ⁇ stainless steels, ⁇ /martensite Maraging steels and cementite steels.
  • Ductility during warm temperature stamping (and superplastic forming) of metals is enhanced by the presence of many grain boundaries, but grain boundaries developed from current casting processes are unsuitable for forming applications because they do not permit rolling or sliding between grains. Grain boundary character has a major effect on the phenomena of sliding and shearing properties of grain boundaries during deformation. Even at modestly elevated temperatures (150-200° C.), Mg alloys can be formed easily by warm forming processes, provided they have a fine grain structure (about 1-3 ⁇ m) and favorable grain boundaries produced by deformation processing. While forming of an alloy at room temperature is preferred, 150-200° C. temperatures are not unusual for inexpensive forming applications (plastics are often formed at such temperatures).
  • Mg parts can be heat treated to grow larger grain size and become creep resistant, or can be alloyed appropriately to make them creep resistant.
  • Low temperature forming can however keep energy usage low during forming and avoid undesirable oxidation encountered during the superplastic forming process.
  • grain boundaries created from the liquid state are crystallographically related, and may possess “special” boundaries that do not permit grain boundary sliding. Special boundaries may have high misorientation angles, but they could have a significant fraction of coincident lattice sites (CSL) and low grain boundary energies to make sliding difficult. While the strain contributed by grain boundary sliding is not large during warm forming, if it is capable of providing accommodation locally, it prevents fracture of the material along grain boundaries. Thus, the boundaries required for enhanced formability must not be those produced by the casting process, but those generated by the plastic working process. The plastic working generates additional dislocations near the grain boundaries and renders then into configurations of higher disorder or higher energy, suitable for enhanced formability.
  • an end resultant can be produced, by initially providing a net-shape sheet bar alloy with a uniform microstructure and an original fine grain size of less than 10 ⁇ m through rapid cooling during forming, without segregation through the thickness of the material.
  • This can be achieved by various forming methods including injection molding and other variations on injection molding, including semi-solid metal injection molding, extrusion molding, TRC (hot rolled).
  • the microstructure is refined to a nano-structure by processing the sheet into an untextured sheet that exhibits superior formability. This can be achieved by hot-pressing, rolling or other processes utilizing appropriately shaped surfaces in the dies as previously discussed.
  • the final net-shaped part is thereby after formed by either superplastic forming (SPF), warm drawing, warm stamping or other methods.
  • SPF superplastic forming
  • warm drawing warm drawing
  • warm stamping warm stamping
  • Initial grain size may be reduced to lower the SPF working stress, to lower the SPF temperature for better surface finishes, and to raise the SPF rate.
  • One the net-shaped part is formed, optional heat treating (annealing, etc.) may be done to the final part to grow the grains so as to stop SPF and to impart creep resistance to the final article.
  • the process starts with un-textured sheet alloy having a fine grain size of less than 10 ⁇ m.
  • the sheet alloy may be two phase and/or include high-angle grain boundaries; the former to control grain growth, promote grain boundary shear during SPF and strengthen the final part, and the latter to promote final net shaping and decrease texture.
  • the coarse second phases are further sub-divided and/or reprecipitated into nano-sized arrays. In the above, twinning and the generation of textures are both minimized.
  • a commercial AZ31B Mg alloy in the form of hot-rolled plate, with thickness of 6.35 mm was used as a precursor material work piece.
  • the chemical composition of this alloy is 3.0 wt % Al, 1.0 wt % Zn, 0.45 wt % Mn and the balance Mg.
  • An 89 ⁇ 89 mm square work piece was cut from the as-received plate, and then processed by SWP as described above.
  • the initial bimodal structure of the as-received alloy was refined into a nearly uniform ultrafine grain structure.
  • the bimodality of the initial structure and its change toward a more uniform structure were characterized by a detailed grain size distribution analysis using known computer image analysis software.
  • the initial bimodal microstructure of the as-received alloy contains 31% area fraction of coarse grains of size 22.1 ⁇ m, but has an average grain size of 9.8 ⁇ m.
  • the final microstructure after SWP had an average grain size of 1.4 ⁇ m, which contained less than 3% area fraction of coarse grains.
  • the post uniform strain depends on strain rate sensitivity, m.
  • m strain rate sensitivity
  • the m value of the as-processed alloy is found to be more than four times that of the as-received alloy. This is a remarkable improvement at room temperature.
  • Uniform strain does not change with the grain size monotonically.
  • the ultrafine grained sample has the lowest uniform strain. With grain size increasing, the uniform strain first rises, and then decreases after a critical size of about 5 ⁇ m.
  • the yield strength was lower than that for tension, but a significant increase in strength occurred in comparison with the as-received alloy, and no concave curve for strain hardening behavior is observed.
  • the difference in the yield strength for in-plane tension and compression decreased as grain size becomes finer. Similar behavior is seen in terms of strain hardening. This suggests that the anisotropy in strength for in-plane deformation decreases due to grain refinement.
  • the as-processed and as-received materials have similar yield strength, but the ultimate tensile strength for the fine grain processed material is higher indicating that strain localization in the coarse grain alloy causes a premature peak in the flow stress.
  • Table 2 shows that the fine grain as-processed alloy has improved mechanical properties such as higher tensile yield strength and higher post-uniform elongation, and higher (R) value. Annealing increases tensile elongation values further. When examined for microstructural changes, no twinning was observed in the processed material. Further, the as-received alloy displayed a rough surface similar to “orange peel” white effect, the fine grain processed alloy exhibited a smooth surface after the test. In addition, the degree of necking is found more gradual in the as-processed alloy.
  • grain refinement increases yield strength and reduces strain hardening rate in the fine grain processed alloy in comparison to coarse grain as-received alloy.
  • the high strain rate sensitivity, m found in the fine grain condition has no connection with texture, but rather is related to the many grain boundaries present in the structure, and it is well-known that a higher m promotes increased elongation by delaying the tendency for strain localization. In the fine grain alloy no twinning was seen, therefore it is believed that dislocation process primarily accommodates plastic deformation in the fine grain alloy. Yield strength for the fine grain alloy is higher due to its finer structure (i.e., smaller spacing between barriers to dislocation) and large fraction of grain (or subgrain) boundaries. More grain boundaries assist in the dynamic recovery process. This, combined with a tendency for shearing or sliding along grain boundaries, increases strain rate sensitivity in the fine grain alloy.
  • Cross slip of prismatic or pyramidal ⁇ a> dislocations can promote high R-value in basal textured sheet for in-lane tensile deformation, while extensive ⁇ c+a> slip may not increase because a decrease in the R-value, particularly if shearing along many grain boundaries occurs.
  • non-basal ⁇ a> slip may be favored in the fine grain processed alloy for in-plane tension.
  • the yield strength for in-plan tension is found to be greater than that for compression even though twinning is inhibited.
  • grain boundary regions experience a greater degree of strain incompatibility and more complex loading than in cubic metals.
  • changes in local stress-state and stress-concentration can be a significant contributor to the deformation mechanics of polycrystal.
  • an Mg-9Al alloy (AZ91D) sheet bar measuring 100 ⁇ 150 ⁇ 3 mm was semi-solid metal injection molded in a commercial 280 ton Thixomolding® machine at Thixomat, Inc. (Ann Arbor, Mich.). This sheet bar was pressed at 190° C. between opposing sine-wave dies having a corrugated surface pattern through 4 cycles, turning the sheet 900 between cycles. The sheet was press flattened after the 4 th pressing cycle. The total reduction of thickness was from 3 mm to 0.8 mm, i.e. 73%. The resultant tensile strengths are compared to commercial AZ31 (Mg-3Al) sheet in Table 3. TABLE 3 Material 0.2% YS, MPa UTS, MPA AZ91D, as injection molded 150 220 sheet bar AZ91D, SWP 4 Cycles 260 300 AZ31, commercial sheet* 150 255 *ASM Handbook
  • yield strength was increased by 73% compared to the original sheet bar and the commercial AZ31. Ultimate tensile strength was respectively increased 36% and 18%.
  • the fine grained original liquid region of the as semi-solid metal injection molded sheet bar had a 772 MPa hardness, which was increased to 932 MPa by SWP. Annealing at 150° C. increased the hardness further to 958 MPa.
  • the SWP material from AZ91 D was harder than equivalent grain size AZ31. Part of this hardness increment over AZ31 is believed attributable to nano-size ⁇ phase in the Al rich AZ91 D alloy. Microstructures confirmed that the coarse ⁇ phase of the starting material had been sub-divided and reprecipitated as nano-particles, some at grain boundaries.
  • the depth of cup produced via a bulge test of the SWP AZ91D is deeper than that of a sheet (of corresponding thickness) of the starting material formed by Thixomolding (semi-solid metal injection molding process of Thixomat, Inc., Ann Arbor, Mich.) only. In fact, the depth is much greater than that formed in commercial 10-20 ⁇ m AZ31 sheet.
  • Mg alloy While illustrated above with Mg alloy, other alloys, capable of being processed into a precursor work piece having an initial fine grain structure, are believed to be suitable to the present invention and include, without limitation, Al, Zn, Ni, Cu, ⁇ / ⁇ Ti, steels, duplex ⁇ / ⁇ stainless steels, ⁇ / ⁇ steels, ⁇ /martensite Maraging steels and metal/ceramic particle composites.
  • SWP of suitable alloys should reduce the cost of making thin sheet material by eliminating multiple stages of rolling and annealing.
  • Deformation by SWP changes the grain boundary character and increases the ability to be formed by warm forming or by superplastic deformation. If sinusoidal deformation is carried out immediately following injection molding, the sensible heat in the molded blank can be utilized. Following immediate rolling or pressing of the sheet bar, it can be formed by SPF into complex part shapes. Such forming can be accomplished at 200° C.
  • the entire component fabrication technology can be set into a continuous operation without storage of coils of sheets, considerable coil annealing, coiling and uncoiling operations. The removal of all of the steps involved with coiling and cranes handling transport of coils would minimize investment in plants. A leaner manufacturing process for parts would emerge.
  • SWP can be accomplished by integrating injection molding machines for metal with conventional pressing and rolling equipment and should be feasible on process equipment already used in the aerospace and automotive industries. Deep drawing also can be practiced on conventional presses.

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