Shear-assisted extrusion with variable extrudate properties

Abstract

A method for shear-assisted extrusion of a billet or feedstock can involve extruding a first portion of the feedstock through a die opening while rotating the die face relative to the feedstock at a first rotational rate and applying a first axial extrusion force. A second portion of the feedstock can be extruded through the opening while rotating the die face at a second rotational rate and applying a second axial extrusion force. This can establish different temperature ranges at the interface for each portion, resulting in a first extruded portion with different physical properties than the second extruded portion.

What is claimed is: 
     
         1 . A method for shear-assisted extrusion of a billet or other feedstock, the method comprising:
 extruding a first portion of the feedstock through an opening defined by a die tool, the extruding comprising establishing rotation of a die tool face relative to a feedstock material according to first specified operating parameters and, contemporaneously, applying an axial extrusion force to drive the feedstock and the die tool face together according to the first specified operating parameters; and   extruding a second portion of the feedstock through the opening defined by the die tool, the extruding comprising establishing rotation of the die tool face relative to the feedstock material according to second specified operating parameters and contemporaneously, applying the axial extrusion force to drive the feedstock and the die tool face together according to the second specified operating parameters, wherein at least one of the second specified operating parameters is different than at least one of the first specified operating parameters to establish different specified temperature ranges at an interface between the die tool face the feedstock such that a first portion of a resulting extrudate along a first axial region extruded from the first portion of the feedstock comprises one or more different physical properties than a second portion of the resulting extrudate along a second axial region extruded from the second portion of the feedstock.   
     
     
         2 . The method of  claim 1 , wherein the first specified operating parameters define a first rotational rate for the rotation during extrusion and the different second specified operating parameters define a different second rotational rate for the rotation during extrusion. 
     
     
         3 . The method of  claim 1 , wherein the first specified operating parameters define a first ram rate used for applying the axial extrusion force and the different second specified operating parameters define a different second ram rate use for applying the axial extrusion force. 
     
     
         4 . The method of  claim 1 , comprising modulating at least one of a rotational rate for the rotation, a ram rate, or ram force used for applying the axial extrusion force, a spindle power, a die temperature, an extrudate speed, a cooling or quenching parameter, or a ramping or other change in one or any combination thereof. 
     
     
         5 . The method of  claim 1 , wherein the feedstock comprises an aluminum alloy. 
     
     
         6 . The method of  claim 1 , wherein the feedstock comprises a 2-series, 6-series, or 7-series aluminum alloy. 
     
     
         7 . The method of  claim 1 , comprising accelerating or decelerating the rotation, without stopping the rotation, to transition from a first rotational rate associated with the first specified operating parameters to a second rotational rate associated with the different second specified operating parameters. 
     
     
         8 . The method of  claim 7 , comprising reducing, without interrupting, a ram rate associated with applying the axial extrusion force contemporaneously with the accelerating or the decelerating the rotation. 
     
     
         9 . The method of  claim 8 , wherein a first steady-state ram rate associated with applying the axial extrusion force corresponding to the first specified operating parameters and a second steady-state ram rate associated with applying the axial extrusion force corresponding to the different second specified operating parameters are the same. 
     
     
         10 . The method of  claim 1 , comprising:
 extruding a transition portion located between the first portion and the second portion; wherein the transition portion of a resulting extrudate along a transition axial region extruded from the transition portion of the feedstock is located between the first axial region and the second axial region.   
     
     
         11 . The method of  claim 10 , wherein the transition axial region defines a region extending no longer than 30 millimeters (mm) in an axial direction. 
     
     
         12 . The method of  claim 1 , wherein a tensile strength of the extruded transition portion along the transition axial region is greater than at least one of the tensile strength of the extruded first portion or the tensile strength of the extruded second portion. 
     
     
         13 . The method of  claim 1 , wherein the one or more different physical properties of the first axial region and the second axial region include respective values of ductility differing by at least 15%. 
     
     
         14 . The method of  claim 1 , wherein the one or more different physical properties of the first axial region and the second axial region include respective values of tensile strength differing by at least 25%. 
     
     
         15 . A shear-assisted extrusion product, comprising:
 a first portion of extrudate along a first axial region extruded from a first portion of a feedstock;   a second portion of extrudate along a second axial region extruded from a second portion of a same feedstock; and   a transition region between the first axial region and the second axial region;   wherein the first portion of the extrudate comprises one or more different physical properties than the second axial portion.   
     
     
         16 . A system for shear-assisted extrusion of a billet or other feedstock, the system comprising:
 a die tool, comprising a die tool face and defining an opening for extruding a first portion of the feedstock therethrough, the die tool configured to have relative rotational motion relative to a feedstock material according to first specified operating parameters;   a driver configured to apply an axial extrusion force to drive the feedstock and the die tool face together, during the relative rotational motion and according to the first specified operating parameters; and   a system controller configured to establish or adjust rotation of the die tool face relative to the feedstock material according to second specified operating parameters and contemporaneously, establish or adjust the axial extrusion force to drive the feedstock and the die tool face together according to the second specified operating parameters;   wherein at least one of the second specified operating parameters is different than at least one of the first specified operating parameters to establish different specified temperature ranges at an interface between the die tool face the feedstock such that a first portion of a resulting extrudate along a first axial region extruded from the first portion of the feedstock comprises one or more different physical properties than a second portion of the resulting extrudate along a second axial region extruded from the second portion of the feedstock.   
     
     
         17 . The system of  claim 16 , wherein the first specified operating parameters define a first rotational rate for the rotation during extrusion and the different second specified operating parameters define a different second rotational rate for the rotation during extrusion. 
     
     
         18 . The system of  claim 16 , wherein the first specified operating parameters define a first ram rate used for applying the axial extrusion force and the different second specified operating parameters define a different second ram rate use for applying the axial extrusion force. 
     
     
         19 . The system of  claim 16 , comprising a thermocouple arranged to provide an indication of an temperature at an interface between the feedstock and the die face, wherein the system controller is configured to modulating at least one of a rotational rate for the rotation, a ram rate, or a ram force used for applying the axial extrusion force based on the indication of the temperature at the interface. 
     
     
         20 . The system of  claim 16 , wherein the system controller is configured to accelerate or decelerate the rotation, without stopping the rotation, to transition from a first rotational rate associated with the first specified operating parameters to a second rotational rate associated with the different second specified operating parameters.