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

Abstract

A method and apparatus for producing ultra-fine grained metal material sheets. The apparatus molds and rapidly solidifies a metal material to form a fine grain precursor. The precursor is then subjected to a series of successive alternating tensile and compressive strains that alter the grain structure of the precursor so as to form a ultra fine grained structure in sheet form. The sheet form may then be subjected to superplastic forming to form a net shaped article.

1 . 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.    
   
   
       2 . The method of  claim 1  wherein the step of molding and solidifying develops a mutliphased microstructure in the fine grained precursor.  
   
   
       3 . The method of  claim 2  wherein the multiphased microstructure includes pinning particles that minimize grain growth.  
   
   
       4 . The method of  claim 1  wherein the step of imparting plastic deformation includes the step of storing dislocations in the microstructure.  
   
   
       5 . The method of  claim 1  wherein the 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.  
   
   
       6 . The method of  claim 1  wherein the molding step and the imparting plastic deformation step are performed in an integrated apparatus.  
   
   
       7 . The method of  claim 1  wherein the molding step and the imparting plastic deformation step are performed by separate machines.  
   
   
       8 . The method of  claim 1  wherein the molding step includes semisolid metal injection molding of the metal material.  
   
   
       9 . The method of  claim 1  wherein the molding step includes one of extruding of the metal material and twin roll casting of the metal material.  
   
   
       10 . The method of  claim 1  wherein the imparting plastic deformation step includes corrugating the precursor in a first direction and subsequently corrugating the precursor in a second direction.  
   
   
       11 . The method of  claim 10  wherein the second direction is orthogonal to the first direction.  
   
   
       12 . The method of  claim 10  wherein the second direction is aligned with the first direction.  
   
   
       13 . The method of  claim 10  wherein the imparting plastic deformation step further includes the step of flattening the precursor.  
   
   
       14 . The method of  claim 13  wherein the flattening step is performed after at least one of the steps of corrugating the precursor in the first direction and the second direction.  
   
   
       15 . The method of  claim 14  wherein the imparting plastic deformation step further includes the step of corrugating in a third direction and a fourth direction.  
   
   
       16 . The method of  claim 15  further wherein a second flattening step is performed after at least one of the third and fourth corrugating steps.  
   
   
       17 . The method of  claim 1  further comprising, after the step of imparting plastic deformation, the step of net shaping the nano-sized grain structure sheet.  
   
   
       18 . The method of  claim 17  further comprising the step of heat treating the net shaped part to impart creep resistance to the net shaped part.  
   
   
       19 . The method of  claim 17  wherein the step of net shaping includes one of stamping, drawing, deep drawing and superplastic forming.  
   
   
       20 . The method of  claim 17  wherein the step of net shaping forms an automotive component.  
   
   
       21 . An apparatus for performing the method of  claim 1 .  
   
   
       22 . An article formed by the method of  claim 1 .  
   
   
       23 . The method of  claim 1  further comprising the step of providing the sheet form with a thickness being less than that of the precursor.  
   
   
       24 . The method of  claim 1  wherein the metal material is a metal alloy.  
   
   
       25 . The method of  claim 1  wherein the metal material is a magnesium alloy.  
   
   
       26 . The method of  claim 1  wherein the metal material is one selected from the group of aluminum alloy, zinc alloy, nickel alloys, copper alloy, α/β titanium alloy, steels, duplex α/γ stainless steels, α/γ steels, γ/martensite Maraging steels and metal/ceramic particle composites.  
   
   
       27 . The method of  claim 1  wherein the step of imparting plastic deformation includes die pressing of the fine grain precursor.  
   
   
       28 . The method of  claim 1  wherein the step of imparting plastic deformation includes rolling the fine grain precursor.  
   
   
       29 . The method of  claim 1  wherein sheet form is provided having a grain structure of less than about 2 micrometers.  
   
   
       30 . The method of  claim 1  wherein the sheet form is provided having a grain structure of less than about 1 micrometer.  
   
   
       31 . The method of  claim 1  where the step of imparting plastic deformation is performed while the precursor is heated above ambient.  
   
   
       32 . The method of  claim 1  wherein the step of imparting plastic deformation imparts tensile strain and compressive strain in a strain direction.  
   
   
       33 . The method of  claim 32  wherein 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.  
   
   
       34 . The method of  claim 33  wherein 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.  
   
   
       35 . The method of  claim 34  whereby 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.  
   
   
       36 . 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 tensile and compressive strain into the precursor article, the plastic deformation means deforming the precursor article into a corrugated work piece and 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; the plastic deformation means further including flattening means for flattening the corrugated work piece into a sheet form of the metal material having an ultra-fine grain size.    
   
   
       37 . The apparatus of  claim 36  wherein the opposed forming members are dies.  
   
   
       38 . The apparatus of  claim 36  wherein the opposed forming members are rolls.  
   
   
       39 . The apparatus of  claim 36  wherein the plastic deformation means includes means for imparting tensile strain and compressive strain into the precursor article.  
   
   
       40 . The apparatus of  claim 39  wherein 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.  
   
   
       41 . The apparatus of  claim 40  wherein the second direction is orthogonal to the first direction.  
   
   
       42 . The apparatus of  claim 40  wherein the second direction is aligned with the first direction.  
   
   
       43 . The apparatus of  claim 40  wherein the plastic deformation means is configured to impart third corrugations and fourth corrugations into the work piece.  
   
   
       44 . The apparatus of  claim 43  wherein the third and fourth corrugations are respectively oriented in the direction of the first and second corrugations.  
   
   
       45 . The apparatus of  claim 44  wherein the third and fourth corrugations are out of phase with the first and second corrugations.  
   
   
       46 . The apparatus of  claim 45  wherein the third and fourth corrugations are respectively 180 degrees out of phase with the first and second corrugations.  
   
   
       47 . The apparatus of  claim 36  further comprising net shaping means for shaping the sheet form of the metal material into a net-shaped article.  
   
   
       48 . The apparatus of  claim 47  wherein the shaping means is one of a drawing press and a superplastic forming machine.  
   
   
       49 . The apparatus of  claim 36  wherein the receptacle, feeder, heating means, discharge means and forming means are part of an injection molding machine.  
   
   
       50 . The apparatus of  claim 36  wherein the receptacle, feeder, heating means, discharge means and forming means are part of a semi-solid metal injection molding machine.  
   
   
       51 . The apparatus of  claim 36  wherein 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.  
   
   
       52 . The apparatus of  claim 51  wherein the flattening means imparts, at least in part, compressive strain to the work piece.  
   
   
       53 . The apparatus of  claim 52  wherein 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.  
   
   
       54 . 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;    after the step of initially increasing the line length, decreasing the line length of the work piece;    after the step of decreasing the line length, then increasing the line length of the work piece; and    flattening the work piece to form an ultra fine grain structured sheet form.    
   
   
       55 . The method of  claim 54  further wherein the step of flattening the work piece is performed before the decreasing and increasing step and then again after the decreasing and increasing step.  
   
   
       56 . The method of  claim 54  wherein the step of flattening the work piece is performed after the decreasing step and the subsequent increasing step.  
   
   
       57 . The method of  claim 54  wherein the initially increasing step introduces strain into the work piece in a first direction.  
   
   
       58 . The method of  claim 54  wherein the decreasing and increasing step introduces strain into the work piece in a second direction.  
   
   
       59 . The method of  claim 58  wherein the second direction is orthogonal to the first direction.  
   
   
       60 . The method of  claim 58  wherein the second direction is generally aligned with the first direction.