High-strength mechanical and structural components, and methods of making high-strength components

Abstract

The invention includes components comprising an alloy containing a base metal and less than or equal to 30% alloying elements. The material has a grain size of less than or equal to about 30 microns and an absence of voids and inclusions of a size greater than 1 micron. The components have a yield strength at least 50% greater than the identical alloy composition in the 0 temper condition. Where the material is heat treatable, the yield strength is at least 10% greater than the identical composition in the T6 temper condition. The invention includes a method of producing components by casting and initial treatment to form a billet. The billet is subjected to equal channel angular extrusion and subsequent annealing at a temperature of less than or equal to 0.85 times the minimum temperature for inducing growth of submicron grains to over 1 micron.

Description

TECHNICAL FIELD

The invention pertains to high-strength engine components, vehicle structural components, methods of producing engine components and methods of forming vehicle structural components.

BACKGROUND OF THE INVENTION

Development of lightweight materials which can contribute to weight reduction of land, air and space vehicles has become increasingly important. Vehicle weight reduction can result in increased fuel efficiency and reduced emissions. Lighter weight materials also offer improved maneuverability and can additionally reduce manufacturing costs.

Many of the available lightweight materials lack sufficient strength for many structural and engine components. Current materials which are considered to be “lightweight” materials for use in engine or body components of vehicles include, for example, magnesium, aluminum, titanium and beryllium metals and alloys. Optionally, medium-weight materials such as steels are used due to their relatively high-strength and thermal stability. However, there is increased drive to reduce the volume of such medium-weight materials to decrease overall engine and/or vehicle weight. Accordingly, the overall strength and thermal stability of components formed of such materials are decreased. Additionally, many of the available lightweight materials and lower volume medium weight materials lack sufficient strength to meet engine and/or vehicle performance standards and safety goals. Accordingly, it is desirable to develop alternate high-strength lightweight materials.

SUMMARY OF THE INVENTION

In one aspect the invention encompasses a high-strength engine component comprising an alloy which contains a base metal alloyed with less than or equal to 30% by weight of alloying elements, where the material has an average grain size of less than or equal to about 30 microns. The material has an absence of voids and inclusions of a size greater than 1 micron. The material also has a yield strength (YS) at least 50% greater than the yield strength of the identical alloy composition in an annealed 0 temper condition.

In one aspect the invention includes high-strength engine components comprising a material consisting of an alloy having a base metal alloyed with less than or equal to 30% by weight of alloying elements. The material has an average grain size of less than or equal to about 30 microns, an absence of voids and inclusions of a size greater than 1 micron and contains soluble second phase precipitates having an average size of less than 30 microns. The material has a yield strength at least 10% greater than the yield strength of the identical alloy composition in the T6 temper condition.

In one aspect the invention includes a vehicle structural component comprising a material consisting of an alloy comprising at least two elements selected from Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd. The alloy contains a base metal alloyed with less than or equal to 30% of additional alloying elements by weight. The material has an average grain size of less than or equal to about 30 microns, an absence of voids and inclusions having a size greater than 1 micron, and has a yield strength at least 50% greater than the yield strength of the identical alloy composition in the annealed 0 temper condition.

In one aspect the invention includes a vehicle structural component comprising material consisting of an alloy of at least two elements selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd, the alloy containing a base metal alloyed with less than or equal to 30 weight % of additional alloying elements. The material has an average grain size of less than or equal to 30 microns, has an absence of voids and inclusions having a size greater than 1 micron, and has soluble second phase precipitates with an average size of less than 30 microns. The material's yield strength is at least 10% greater than the yield strength of the identical alloy composition in the T6 temper condition.

In one aspect the invention includes a method of producing an engine component. The method includes providing a cast alloy and performing an initial treatment using at least one of thermal mechanical processing and solutionizing to form a billet. The billet is subjected to at least one pass of equal channel angular extrusion and is subsequently annealed for at least 30 minutes at a temperature of less than or equal to 0.85 T_r, where T_r is the minimum temperature for which a 30 minute anneal of the extruded billet will produce growth of submicron grains to over 1 micron.

In one aspect the invention encompasses a method of forming a vehicle structural component. The method includes formation of a billet of a heat-treatable alloy. The formation of the billet includes casting and solutionizing the material. The billet is subjected to at least one pass of equal channel angular extrusion and is annealed for at least 30 minutes at a temperature of less than or equal to 0.85 T_r, where T_r is the minimum temperature for which a 30 minute anneal of the extruded billet will produce grain growth of submicron grains to over 1 micron.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawings.

FIG. 1 is a diagrammatic view of a portion of a mechanical component in accordance with one aspect of the invention.

FIG. 2 is a diagrammatic view of a portion of a structural component of a vehicle in accordance with one aspect of the invention.

FIG. 3 is a flowchart diagram illustrating methodology encompassed by one aspect of the present invention.

FIG. 4 is a diagrammatic cross-sectional view of a material being treated with an equal channel angular extrusion apparatus in accordance with one aspect of the invention.

FIG. 5 is a diagrammatic view illustrating methodology in accordance with one aspect of the invention.

FIG. 6 shows a comparison of yield strength and ultimate tensile strength for aluminum alloy 6061 processed in accordance with one aspect of the invention relative to conventional T6 and 0 temper Al 6061.

FIG. 7 shows a comparison of Brinell hardness for aluminum 6061 processed in accordance with the invention relative to standard T6 and 0 temper 6061 materials.

FIG. 8 shows a comparison of yield strength and ultimate tensile strength for aluminum alloy 2618 materials processed in accordance with the invention relative to conventional T6 and 0 temper Al 2618 materials.

FIG. 9 shows a comparison of Brinell hardness for aluminum alloy 2618 processed in accordance with the invention relative to conventional T6 and 0 temper Al 2618 materials.

FIG. 10 shows a comparison of the fatigue properties of Al 2618 material processed in accordance with the invention relative to conventional Al 2618 T6 material. Arrows indicate testing was stopped prior to sample failure.

FIG. 11 shows a comparison of maximum fatigue life for materials presented in FIG. 10. Arrows indicate testing was stopped prior to sample failure.

FIG. 12 shows a comparison of yield strength and ultimate tensile strength for aluminum alloy 2219 materials processed in accordance with the invention relative to conventional Al 2219 T6 and 0 temper Al 2219 materials.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention 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).

One aspect of the invention is production of high-strength lightweight materials and mechanical and/or structural components having improved strength and lifetimes. Methods of producing high-strength lightweight materials, engine components and structural components according to the invention are described.

Although lightweight materials have been previously developed which can be utilized in certain instances, improvement of strength and fatigue properties of materials can afford additional safety and an additional decrease in overall weight of engines, vehicles, and machinery. The invention includes engine and structural components formed utilizing methods described herein. In particular instances, the engine or structural component can be part of a vehicle. Such vehicle can be an air, ground, water or space vehicle. Exemplary vehicles include automobiles, airplanes, boats, trains, spacecraft, trucks, bicycles, etc. For purposes of the present description, an engine component can be any element comprised by a motor assembly. For example, components in accordance with the invention can be utilized for motors involved in transportation, power generation, refrigeration/cooling, etc. For purposes of the present description, the term structural component, with reference to a vehicle, can refer to any element involved in the frame, external or internal body, support structures, wheels, casings, housings, brakes, landing systems, etc.

Although the invention is described primarily with respect to vehicle engines and vehicle structural components, it is to be understood that the invention contemplates adaptation of methods and/or product materials for use in alternative engine applications and for structural components of devices and constructions other than vehicles.

One area of particular importance for which the invention is particularly applicable is turbomachinery components such as wheels. For purposes of the present description, the term wheel is utilized to describe a solid or non-solid disk type structure which is rotatable, typically by way of a connected rotary shaft. Exemplary wheels include turbine wheels and compressor wheels.

Metals and alloys conventionally utilized for components such as wheels are typically produced by processing methods which include casting, rolling, forging and in particular instances heat treatment. The mechanical properties of conventional metals and alloys are obtained primarily utilizing one or both of two distinct strengthening mechanisms. These mechanisms are 1) solution or precipitation strengthening, where size and distribution of second phase elements is controlled by specific sequences of heat treatment; and 2) deformation by conventional processing utilizing rolling and or forging which introduces defects such as dislocations or specific texture to provide a strengthening effect. Methods such as rolling or forging can be very inefficient due to the large change in overall shape of a product during the processing which inhibits or prevents introduction of high-level strain into the material. This in turn limits the total level of deformation that can be introduced into a material thereby limiting the refinement of structural units such as grain size. Accordingly, typical grain sizes for conventionally produced materials are usually greater than 10 microns and more typically greater than 50 microns.

Conventional methods utilizing rolling and/or forging additionally result in non-uniform deformation producing non-homogenous grain size and precipitate distribution. In particular instances non-uniform stress-strain gradients are produced between the top surface and a middle thickness of a resulting billet.

Various structural parameters including grain size, grain boundary volume and/or crystalline order can affect strength of lightweight materials. One option for providing strength improvement is by creation of amorphous material having an absence of long range single or polycrystalline order. However, the additional strength imparted in amorphous materials is typically gained at the expense of ductility. Accordingly, amorphous materials may be unsuitable for a variety of applications such as, for example, fabrication of long panels or wheels with complex blade geometries. Although amorphous materials can be utilized in particular instances for specific applications and non-complex shapes, such materials can typically have low thermal stability. Further, bulk production of amorphous materials has yet to be achieved.

Another mechanism for improvement of mechanical properties such as strength is grain refinement. Grain refinement to a sub-micron (100-1000 nm) or nano level (1-100 nm) average grain size can impart significant strength improvement without sacrificing ductility. In fact, in particular instances ductility improvements are obtained simultaneously with increased strength due to a large increase in the volume of grain boundaries in materials having extremely small grain size. Resulting materials can have a wider range of applications relative to amorphous materials, particularly for applications which rely on ductility and formability.

In accordance with the present invention, equal channel angular extrusion is utilized to achieve grain refinement and controlled precipitate formation. Equal channel angular extrusion (ECAE) is a technique which utilizes intense or severe deformation by simple shear of a material to induce grain refinement. The resulting refined structures result in an increase in mechanical properties including tensile strength and hardness. Previously, ECAE has been utilized specifically for high-purity type materials and particularly for non heat-treatable materials. For purposes of the present description heat-treatable materials are those that can be hardened by heat treatment and non-heat-treatable materials are those which are not hardenable and/or can loose strength through thermal treatment. As will be described, the general methodology and processing in accordance with the invention can be modified and adapted based on the heat-treatability of the specific material to be utilized for a particular application.

In general the present invention pertains to methodology for strengthening materials by combining severe plastic deformation techniques such as equal channel angular extrusion with one or more additional strengthening techniques such as, for example, solutionizing, precipitation and texture hardening. The combination of techniques provides materials and products with superior mechanical properties including, strength, hardness, wear and fatigue relative to conventional processing and materials. Materials and products in accordance with the invention can be particularly useful in applications such as engine and structural/body components where high-strength lightweight materials are especially useful.

The combination of ECAE and heat treatments in accordance with the invention can advantageously achieve superior mechanical properties relative to traditional heat treatments alone. These advantages are most notable in heat-treatable metals and alloys. ECAE utilization allows strengthening by grain refinement and additionally allows the rate and extent of precipitation to be controlled, as well as shape, size and distribution of the resulting precipitates. Control of precipitate characteristics is afforded by dynamic precipitation during ECAE. The high strain during ECAE allows very fine precipitates. In particular instances, new grain boundaries and/or dislocations are formed simultaneously with precipitates, the combination of which is responsible for the most intense improvements in mechanical properties. Due to simple shear across the thickness of a material undergoing ECAE, distribution of precipitates is very uniform. The deformation route (sequence of billet rotation between passes) during ECAE can also influence the distribution and shape of precipitates.

Local re-arrangement of atoms during intense strain brought about by ECAE can increase the solubility limit of some elements and/or precipitates. The additional solubility can produce a greater strengthening effect during subsequent heat treatment.

An additional advantage of utilizing ECAE in combination with heat-treatment is the increase in rate of static precipitation during annealing of in ECAE materials. The increase in precipitation rate is due to the increased area of grain boundaries which allows efficient diffusion processes in sub-micron structures. As a result, the time and temperature for achieving peak-aging or over-aging is reduce thereby reducing overall fabrication cost.

One aspect of the invention is described with reference to FIG. 1. FIG. 1 illustrates an exemplary component 10 comprising a wheel 12 in association with a rotary shaft 14. Wheel 12 is illustrated as having an inner radial portion 16, which can be referred to as a hub portion, and an outer radial portion 18. Wheel 12 as illustrated in FIG. 1 is a solid disk type wheel. However, it is to be understood that the invention contemplates alternative wheel types such as, for example, those comprising non-solid disks where outer portion 18 is alternatively shaped or contoured. For example, wheel 12 can be configured to have blades, cogs, teeth, etc. Exemplary wheel types encompassed by the invention include fans, compressor wheels, impellors, turbine wheels, etc. The invention additionally contemplates configurations where the hub portion of the wheel is non-solid.

The radial distances comprised by inner portion 16 and outer portion 18 are not limited to particular values, or to any particular ratio relative to one another. Wheel 12 can be a single piece or can be fabricated as two or more individual pieces. Various engines in which component 10 can be a part include but are not limited to aircraft engines, automobile engines, turbochargers, superchargers, refrigeration systems and other cooling systems, spacecraft, trains and other transportation vehicles. The invention additionally contemplates inclusion of component 10 in accordance with the invention for additional applications such as, for example, additional drive train applications and any other mechanical applications where high-strength lightweight wheels are desired.

In operation, wheels can be subjected to high loads and stresses in a radial direction due to centrifugal forces imparted by high rotational speeds. Stress can be most severe in the central disc (hub) section 16 which supports the radial mass of exterior portion 18. Accordingly, the hub region can be stretched outward under high tangential stresses. Additionally, component 10 can be exposed to high thermal gradient end stresses in addition to cyclic loading. As a result, the blades or outer portion 18 typically achieve a higher temperature relative to central region 16.

Depending upon the particular material and fabrication method, conventional wheels can have a very short finite fatigue life resulting in failure during operation. In particular applications the life of the wheel is the limiting component of an entire engine system. This life limiting aspect is common for applications such as compressor wheels in turbochargers. Conventional wheels for such applications are typically fabricated of cast aluminum or aluminum alloys. Such aluminum materials can be low cost, lightweight and provide low rotational inertia for rapid acceleration response during transient loading. However, conventional casting generates a high degree of metallurgical imperfection such as voids, inclusions, dendrites and/or segregation. As a result, cast aluminum wheels can fail in the hub region resulting in a short life. Although increase in hub thickness can supply additional stiffness and support, the increase in thickness also increases the weight. Increased weight in the disk portion of a rotary component can result in a need for increase dimension in the rotary shaft portion and/or containment walls of the engine or other machinery. Such can further add weight to the overall system.

In particular applications, conventional aluminum materials have been replaced by alternative materials such as titanium and titanium alloys, composite fibers or sintered powders. Titanium materials and alloys have a higher weight relative to aluminum materials however, titanium and alloys thereof have additional strength, thermal stability and fatigue properties relative to aluminum materials and have similar stiffness and blade natural frequencies compared to aluminum materials. However, due to the difficulty in forging and machining of titanium materials, the cost of such materials and components comprising such materials can be especially prohibitive to use in many applications.

Another alternative which has been utilized is a hybrid wheel design where blades or outer diameter portions are manufactured separately from the central disk region. The multi-part wheel is assembled by joining methods such as bolting, brazing or welding. In these instances the central hub region can typically comprise wrought aluminum alloy or forged titanium, with the blades or outer portion comprising cast aluminum or titanium. Exemplary wrought aluminum alloys utilized for this purpose have included heat treatable aluminum alloys from the 2xxx and 6xxx aluminum series (such as Al 2219, Al 2024, Al 2618 and Al 6061). However, these conventional materials have a limited operating speed and pressure ratio. Additionally the hybrid design can lack strength in the joining/bonding region at the interface of inner and outer radial portions.

In particular aspects, an entire wheel assembly (inner and outer radial portions) has been formed from a wrought aluminum alloy. Conventional fabrication of the unitary design can typically comprise hot forging to a near net shape followed by precipitation strengthened heat treatment and machining to a final functional form. Although having somewhat improved mechanical properties with low weight and rotational inertia, such materials and components are unable to meet the ever increasing stringency of service requirements in many applications.

The materials and components in accordance with the invention provide increased strength and mechanical properties relative to conventional components, have improved manufacturing and mechanical properties including strength and fatigue, and can be entirely free of cast defects. The improvement relative to conventional materials is exemplified by various aluminum alloys as presented below. Titanium alloy components in accordance with the invention can also be of particular advantage due to improved strength, manufacturing, and machining properties relative to conventional titanium materials.

Metal component 10 illustrated in FIG. 1 in accordance with the invention can comprise metals including Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, Cd and/or alloys of such metals. For many engine and other mechanical applications, wheel 12 can preferably comprise a metal or alloy containing at least one of Al, Ti, Mg, Be, Ni and Fe. Although the invention is not limited to any particular amount of alloying element content, the most effective amount of alloying element(s) for purposes of the invention has been found to be less than or equal to 30% by weight whether the alloy contains one or multiple alloying elements. In many instances the total percent of alloying elements is preferably less than or equal to 10%, and in some instances is preferably less than or equal to 5%. For purposes of the present description, the term “base element” can be utilized when referring to a single element within an alloy having a content which exceeds any other element within the alloy.

The invention includes, in addition to wheels and other mechanical components, metal structures for use in structural applications. An exemplary structural component 20 in accordance with the invention is illustrated in FIG. 2. As illustrated, component 20 can comprise a sheet structure 22 having a height or thickness ‘d’ which is exceeded by both the length ‘y’ and width ‘x’ of the sheet. It is to be understood that structural component 20 as illustrated in FIG. 2 is but one exemplary structural shape encompassed by the invention and that alternative structural configurations are contemplated. The illustrated sheet type configuration illustrated can be used in applications such as, for example, panels for vehicle bodies (i.e. doors, fenders, fuselage, etc.).

Exemplary materials and preferred materials for structural component 20 can be any of the materials and preferred materials described above with respect to the mechanical component illustrated in FIG. 10. Since similar or identical materials can be utilized in formation of the mechanical component 10 illustrated in FIG. 1 and the structural component 20 illustrated in FIG. 2, materials and common processing of such materials for formation of components in accordance with the invention are concurrently described below. The described materials can undergo additional and distinct processing to produce the desired configuration for a particular application.

Of the materials and alloys indicated above, alloys of particular interest which can be utilized for either structural or mechanical components in accordance with the invention include: aluminum alloys of the 2xxx series (for example, 2618, 2024 and 2219 alloys); aluminum alloys of the 3xxx series; aluminum alloys of the 4xxx series; aluminum alloys of the 5xxx series; aluminum alloys of the 6xxx series (for example, Al 6061), aluminum alloys of the 7xxx series; aluminum lithium alloys; titanium aluminum alloys (for example, Ti6Al4V); and magnesium based alloys (for example, ZK60 and AZ31). Processing of such materials in accordance with the invention can produce structural and engine components which have superior mechanical properties including strength and fatigue relative to conventionally produced materials and components. The additional strength and improved fatigue properties are achieved utilizing a particular processing sequence which includes one or more distinct equal channel angular extrusion (ECAE) treatments at particular processing points, in combination with various conventional type thermo-mechanical processing and/or heat treatments. The particular combination and sequence of processing including severe plastic deformation utilizing ECAE can produce a substantial strengthening effect and improved fatigue which markedly exceeds conventional processing abilities. This improvement in properties imparted by methods of invention can be achieved for heat-treatable as well as non-heat-treatable materials.

Metal parts produced in accordance with the invention such as wheel 12 depicted in FIG. 1 and panel 20 depicted in FIG. 2 have an average grain size of less than 30 microns with a uniform grain size throughout the material. Typically, the uniform average grain size will be less than 1 micron (also referred to as a submicron grain size). In most instances the material and component formed from such material will entirely lack cast defects such as voids and inclusions having a size of greater than 1 micron. Processing in accordance with the invention produces a yield and ultimate tensile strength in resulting materials and components which are at least 50% higher than the corresponding yield and ultimate tensile strength for an identical composition in a standard, fully annealed, 0 temper condition (where all materials are evaluated at room temperature). For non-heat-treatable materials the yield and ultimate tensile strength increase relative to fully annealed 0 temper condition in particular applications can be 100% or more.

Where the material utilized is a heat-treatable alloy, the product material or component produced by methodology in accordance with the invention will also have an average uniform grain size of less than 30 microns and typically less than 1 micron. The product will additionally be free of cast defects such as voids and inclusions having a size greater than 1 micron. Products comprising the heat-treatable alloys will have an average precipitate size of soluble second phases of less than 30 microns and typically less than 1 micron. The yield strength of materials and components produced from heat treatable alloys will be at least 10% higher than the corresponding yield strength and ultimate tensile strength of the identical composition in the standard peak aged T6 condition (optimal precipitation) evaluated at room temperature. For particular products, the material or component will have a yield strength increase of 30% or more relative to standard T6 conditioned material.

Materials and products in accordance with the invention additionally have improved fatigue life. For non-heat-treatable alloys the product fatigue life is improved by at least 5% and typically 20% or more relative to fully annealed 0 temper condition for the corresponding alloy (measured under high cyclic stress). For materials and products produced utilizing heat-treatable materials, the fatigue life of such products is improved by at least 5% and typically by 20% or more relative to standard peak aged T6 condition under high cyclic stress.

General methodology for processing of heat-treatable and non-heat-treatable materials in accordance with the invention can typically include casting of a metal material or alloy, preliminary processing and extruding utilizing equal channel angular extrusion. The general processing can also in some instances utilize annealing at one or more stages of processing of the material. The described methodology can be utilized for forming high-strength lightweight materials and products including, but not limited to, mechanical components and structural components as discussed above.

Methodology of the invention is described generally with reference to FIG. 3. An exemplary processing scheme 100 for treating materials in accordance with the invention is shown. The general outlined process shown in FIG. 3 can be utilized for both heat-treatable and non-heat-treatable alloys. Processing of heat-treatable alloys can typically include additional processing treatments during the overall processing scheme relative to non-heat-treatable alloys as described below.

An initial metal or alloy material can be treated in an initial process stage 110 which includes casting of the material. In particular instances, casting of materials can preferably produce a shaped material, typically rectangular or circular which has dimensions close to final dimensions of the product.

The cast material can subsequently be subjected to preliminary processing step 120. Preliminary processing of non-heat-treatable materials can preferably comprise thermo-mechanical processing of the material without solutionizing. Such processing can include, for example, hot forging, rolling of the material for homogenization, or a combination thereof. Such treatment is preferably sufficiently performed to reduce, and in particular instances, eliminate cast defects and can include forming of a general shape.

Where the material or alloy is heat-treatable, preliminary processing step 120 can further include solutionizing to allow dissolution of all soluble second phases within the material. Such solutionizing can preferably be performed at a temperature and for a sufficient time for complete solublization for the particular heat-treatable alloy being processed. Where solutionizing is utilized, such is preferably immediately followed by quenching. Typically, the quenching will comprise quenching in water and will be performed to quench as quickly as possible, preferably at a rate of greater than or equal to 500° F./s and more preferably at a rate of greater than 1000° F./s.

The preliminary processing performed in step 120 produces a billet which will undergo additional processing in accordance with the invention. The preliminary processing treatment can additionally include preheating of the billet in preparation for subsequent treatment. When utilized, the preheating is conducted at a temperature and for a time below or equal to the temperature and time for peak aging of the particular alloy being treated. Typical preheating temperatures for an aluminum material or alloy, for example, are between 110° C. and 250° C. for a time of 0.5 hours or greater. In particular instances it can be advantageous for rapid preheating methods to be utilized such as, for example, induction heating or infrared techniques. Where rapid preheating is utilized, the treatment at a temperature of between 110° C. and 250° C. will be less than 1 hour and more preferably less than 20 minutes. Such preheating conditions can effectively heat the material to a desired temperature for further processing while minimizing or avoiding growth of precipitates, since such growth can result in a loss of precipitate strengthening ability. It can be advantageous to minimize such loss to allow optimum strengthening. Accordingly, rapid heating techniques are advantageous to reduce total preheating time such that soluble phases do not precipitate and growth of precipitates is minimized.

For some heat-treatable alloys (e.g. aluminum alloys of the 7xxx series), precipitation occurs very quickly (within hours or a few days) even at room temperature. Accordingly, since such precipitation begins immediately after solutionizing and quenching, it can be desirable to refrigerate the quenched billet or store the billet at cryogenic temperatures, preferably less than 0° C. until the time of further processing. The billet can then undergo the preheating step (if utilized for the particular material), preferably by rapid heating techniques immediately prior to plastic deformation (discussed below).

Preliminary processing can additionally include artificial precipitation aging at low temperature over a long period of time where the temperature and time are less than those corresponding to conditions for peak aging. Such artificial precipitation aging can include intermediate aging treatment to stabilize precipitation (similar to a T7 temper for particular alloys) or even peak aging. The particular time and temperature will depend upon the composition of the material being processed. For aluminum alloys a typical artificial precipitation aging will be conducted at a temperature of less than 250° C. for less than 20 hours with preferable conditions being between 100° C. and 200° C. for a time of greater than 0.5 hours. Where a billet is refrigerated or stored at cryogenic temperature, the artificial precipitation can be conducted after such refrigeration and prior to preheating of the billet in preparation for subsequent plastic deformation treatment.

In particular instances whether a heat-treatable or non-heat-treatable alloy is utilized it can be advantageous to perform at least one warm or hot equal channel angular extrusion pass during preliminary processing step 120. Referring to FIG. 4, such illustrates an exemplary ECAE device 50. Device 50 comprises a mold assembly or die 52 that defines a pair of intersecting channels 54 and 56. Intersecting channels 54 and 56 are identical or at least substantially identical in cross-section with the term “substantially identical” indicating the channels are identical within acceptable tolerances of an ECAE apparatus.

In operation, a material is extruded through channels 24 and channel 26 resulting in plastic deformation of the material by simple shear, layer after layer in a thin zone located at the crossing plane of the channels. Lubrication of the channel walls and/or billet can assist in achieving uniform simple shear deformation. Channels 54 and 56 can intersect at an angle of from about 90° to about 140°. The tool angle (channel intersect angle) of about 90° can be preferable since an optimal deformation (true shear strain) can be obtained. Alternative channel shapes can also be utilized relative to that illustrated.

During the preliminary processing stage, the billet of material 60 as shown in FIG. 4 can be extruded by, for example, application of sufficient force utilizing a punch 62 where such force is applied in a downward direction with respect to the depiction in FIG. 4. A second punch 66 can optionally be provided to provide an opposing force at the leading edge of billet 60. The opposing force exerted by second punch 66 is preferably no greater than half the force exerted by punch 62. The opposing force can provide back pressure on the billet during ECAE which can advantageously decrease the risk of crack generation and surface defects in billets at lower processing temperatures, especially at high levels of deformation. Application of back pressure can be especially useful where the material being processed is brittle. Accordingly, the time and die temperatures for ECAE processing can be reduced enabling working conditions at temperatures less than those of peak aging and for a time less than that of peak aging conditions.

As an alternative to the second opposing punch technique depicted in FIG. 4, an alternative technique for providing back force can be utilized as depicted in FIG. 5. As shown, a slider 70 can be provided along an edge of billet 60 during equal channel angular extrusion in conjunction with a bar 72 for exertion of back pressure opposing the direction of extrusion. Further, the degree of lubrication between interfacing surfaces of the slider and the die can be utilized to increase the amount of back pressure encountered by the billet.

Where one or more passes of ECAE is utilized during preliminary processing 120, such is preferably performed after casting and before any heat treatment such as solutionizing. The inclusion of one or more passes, preferably one or two passes of ECAE during preliminary processing can advantageously breakdown cast defects such as voids, pores and dendrites, and aid in homogenizing the structure prior to subsequent treatments of the material. In heat treatable alloys the initial ECAE step can additionally increase the solubility limit of soluble phases within the material. Such increased solubility can maximize strength enhancing precipitation that occurs during a subsequent solutionizing event. Where ECAE is included in the preliminary treatment, the ECAE die should have a temperature of at least 250° C. and preferably a temperature of at least 350° C.

Upon completion of preliminary processing step 120 the resulting billet, whether of heat-treatable or non-heat-treatable material, is subjected to a severe plastic deformation treatment 130 as illustrated in FIG. 3. The severe plastic deformation treatment preferably comprises at least one equal channel angular extrusion pass and more preferably from one to four passes. Such passes can be performed by any route; however it can be advantageous to rotate the billet by 90° between at least some of the passes. Rotation of the billet between passes allows strain paths to be achieved and can allow controlling of shape and structural units including grain size and/or crystallographic texture.

ECAE can introduce severe plastic deformation in the preliminary processed material while leaving the dimension of the block of material unchanged. ECAE can be a preferred method for inducing severe strain in a metallic material in that ECAE can be utilized at low loads and pressures to induce strictly uniform and homogenous strain. Additionally, ECAE can achieve high deformation per pass (true strain ε=1.17); can achieve high accumulated strains with multiple passes through an ECAE device (at n=4 passes, ε=4.64); and can be utilized to create various textures/microstructures within materials by utilizing different deformation routes (i.e. by changing an orientation of the billet between passes through an ECAE device).

The material being processed by ECAE can be passed through the ECAE apparatus several times and with numerous routes. ECAE processing in accordance with the invention will typically include at least two passes in order to produce a sub-micron structure. Where intermediate annealing between passes is utilized (pre-heating of the billet) or where the die are heated during ECAE passes, the temperature utilized is preferably less than a temperature which would cause an increase in grain size over 1 micron for the particular material being processed. Although methods of the invention can be utilized to produce materials having an average grain size greater than one micron, parameters will typically be chosen to maintain an average grain size of not greater than 30 microns.

Although the invention contemplates ECAE processing under cold or hot processing conditions, ECAE processing will typically comprise one or more passes conducted at a temperature below the peak aging temperature of the particular material. For aluminum alloys, exemplary temperatures are temperatures less than 300° C., preferably between 110° C. and 225° C. For titanium materials and alloys, ECAE processing in accordance with the invention is typically conducted at a temperature of less than 800° C.

During the severe plastic deformation treatment, intermediate preheating of the billet between each pass can be performed by, for example, rapid heating techniques such as induction or infrared heating. Preferably, the preheating temperature and time is less than those corresponding to peak aging conditions. For aluminum or aluminum alloys preferable temperatures are between 110° C. and 250° C. for less than or equal to 0.5 hours. ECAE processing can additionally comprise quenching of the billet after each ECAE pass with such quenching preferably being conducted in water. Heating of die and/or billets for ECAE processing can enhance diffusion mechanisms and thereby provide better structure homogeneity. Small homogenous and highly uniform structure achieved by ECAE can afford increased or maximized material strength.

Where the material being processed is a non-heat-treatable alloy the one or more ECAE passes are preferably conducted at the lowest processing temperature for achieving good surface conditions. For aluminum alloys which are non heat-treatable, such processing is preferably conducted at a temperature of less than 300° C. and more preferably at a temperature of from 110° C. to about 225° C. Intermediate preheating of non-heat-treatable billets between each pass (intermediate annealing) can additionally be performed preferably by rapid heating techniques as described above.

As illustrated in FIG. 3, the resulting extruded billet from deformation processing event 130 is subjected to a post deformation anneal per treatment 140 as illustrated in FIG. 3. The post deformation anneal comprises annealing at a low temperature for several hours. This anneal can preferably be performed at a temperature T of less than 0.85 T_r, where T_r is the time required to grow grains within the material to over 1 micron when annealed at such temperature for greater than or equal to 30 minutes. (Where the material being annealed has an average grain size of over 1 micron prior to annealing T_r refers to the temperature at which grains within a submicron grain material of an identical composition would grow to a grain size of over 1 micron). For aluminum alloys the post deformation anneal is preferably conducted at a temperature of between 100° C. and 200° C. for a time of at least 30 minutes. Typical treatments can be, for example, a 150° anneal for 1-8 hours. Performing an anneal at or near T_r for the particular material can advantageously produce average grain sizes of from about 1 micron to about 30 microns which can facilitate forming.

Post deformation annealing of materials in accordance with the invention can result in fine precipitates, the amount of which can be enhanced by the increased solubility induced by performing ECAE in preliminary treatments as described above. The post deformation anneal can advantageously impart improved fatigue properties relative to conventional materials and relative to materials not subject to anneal. Additionally, the post deformation annealing achieves superior fatigue properties at a faster rate than peak aging treatment.

Upon completion of the post deformation anneal, the resulting material can be further processed to produce various mechanical components such as, for example, the wheel of component 10 depicted in FIG. 1, or structural components such as, for example, the panel of component 20 shown in FIG. 2. Exemplary further processing can comprise machining, forming (e.g. by rolling, stretching, bending, forging, drawing, hyroforming, superplastic forming, etc.), joining (via mechanical joining, brazing, solid state bonding, welding, friction stir processing, etc.), and/or surface treatment (e.g. coating, shot peening). The resulting components can have the characteristics of properties described above throughout most or all of their volume.

Methodology in accordance with the invention enhances strength of heat-treatable and non-heat-treatable materials compared to the strongest standard tempered materials of the same alloying composition. The materials additionally demonstrate enhanced fatigue properties compared to the corresponding alloy having standard commercial temper where resistance of such processed materials in accordance with the invention is also enhanced relative to conventional temper materials.

EXAMPLE 1

Heat-Treatable Al 6061

The aluminum alloy designated as Al 6061 is widely used for structural applications including various aerospace applications. Conventional Al 6061 T6 temper is produced by solutionizing, quenching and artificial peak aging at 175° C. for 8 hours. Such is the strongest temper of this alloy obtainable by precipitation treatment alone. Standard Al 6061 0 temper is obtained by fully annealing of the alloy at a temperature of 400-450° C. for several hours. It is the lowest strength commercially available 6061 material. The yield strength and ultimate tensile strength of 0 temper and T6 6061 alloys is presented in FIG. 6 for comparison purposes relative to yield strength and ultimate tensile strength achieved utilizing methodology in accordance with the invention.

Three samples were prepared by processing in accordance with the invention. The ultimate tensile strength and yield strength of each of the three samples are presented in FIG. 6. Sample 1 was prepared by subjecting Al 6061 to solutionizing treatment followed by quenching. The quenched material was processed through 4 passes of equal channel angular extrusion and was short term annealed at 150° C. for 1 hour.

Sample 2 was prepared by solutionizing Al 6061 followed by immediate quenching and standard artificial peak aging at 175° C. for 8 hours. Aging was followed by 4 passes of equal channel angular extrusion at a die temperature of less than 170° C.

Sample 3 was prepared by solutionizing Al 6061 alloy followed by immediate quenching. The quenched billet was subjected to 4 passes of equal channel angular extrusion followed by long term annealing at 150° C. for 8 hours.

For each of the three samples, the solutionizing was conducted at 500° C. for several hours and quenching was performed in water. As illustrated in FIG. 6, equal channel angular extrusion treatment produces an increase in yield strength of 40-70%, and an increase in ultimate tensile strength of 30-35% compared to standard 6061 aluminum in T6 condition. A similar increase in Brinell hardness (30-50%) is also achieved as illustrated in FIG. 7. It is noted that because Al 6061 T6 is strengthened relative to 0 temper by precipitation strengthening only, the additional increase provided in the materials of the present invention is due to grain refinement achieved during equal channel angular extrusion. The increase in strength due to ECAE process is more evident as compared to Al 6061 0 temper with an increased yield strength of 600-750%, and an increased ultimate tensile strength and hardness of 200-280%.

It is noted that Sample 1 has achieved the highest strength while utilizing the simplest and fastest heat treatment. For Al 6061 the maximum strengthening effect was observed when ECAE directly follows solutionizing and quenching in accordance with the invention.

EXAMPLE 2

Heat-Treatable Al 2618 Alloy

Aluminum alloy having designation Al 2618 has been utilized for applications such as engine components, for example, compressor wheels and in turbocharger applications due to its thermal stability up to 250° C. Standard Al 2618 in T6 condition is the strongest commercially available temper for the alloy. The yield strength and ultimate tensile strength of such material is shown in FIG. 8. The ultimate tensile strength and yield strength of standard Al 2618 in the 0 temper condition is also shown in FIG. 8.

Al 2618 was processed in accordance with the invention combining ECAE processing and heat-treatment. The treatment included solutionizing the 2618 material followed by ECAE. It was found that performing ECAE directly after solutionizing and quenching resulted in the highest strengthening effect. Equal channel angular extrusion was performed using die temperatures between 150° C. and 200° C. with intermediate annealing at similar temperatures.

After equal channel angular extrusion, the resulting billet was subjected to low temperature heat-treatment as described in the methodology section. The yield strength and ultimate tensile strength of the 2618 materials in accordance with the invention after 1 pass of ECAE and after 2 passes of ECAE are presented in FIG. 8. It is noted that only 2 passes of ECAE results in higher strength than does deformation with additional passes and is sufficient to produce a sub-micron structure.

As compared to standard Al 2618 in the T6 condition, materials processed in accordance with the invention have increased yield strength and ultimate tensile strength of 10-50% and 10-35% respectively. As compared to standard Al 2618 in the 0 temper condition, the increase is more marked with an increase of from 430-650% in yield strength and 175-250% ultimate tensile strength increase.

The increase in material hardness for Al 2618 due to processing in accordance with the invention is presented in FIG. 9. As shown, the hardness increase achieved by processing in accordance with the invention is 10-45% as compared to Al 2618 in the T6 condition. For 1 and 2 passes of equal channel angular extrusion, superior hardness is achieved for temperatures up to 250° C. This is an advantageous result since the maximum surface temperature of compressor wheels is typically less than 200° C. The use of rapid heating treatment results in similar improvements in strength, hardness and fatigue properties and additionally allows faster processing times.

Results of fatigue testing are presented in FIGS. 10 and 11. Material processed in accordance with the invention is compared in these figures to ECAE Al 2618 in peak aged condition (T6). For samples processed in accordance with the invention, Al 2618 material was cast, forged, solutionized followed by immediate quenching and subsequently processed by one pass of equal channel angular extrusion at a temperature below 200° C. ECAE was followed by annealing at 150° C. for 6 hours. Fatigue testing was performed utilizing high cycle fatigue tests conducted under various stresses (35-60 ksi) at a frequency of 60 Hz. Testing was performed at room temperature for an R ratio equal to 0. Samples which were stopped prior to breakage of the sample (indicated by arrows in the corresponding figures) were concluded at 10 E7 cycles, with testing of one sample being stopped after 10 E8 cycles without failure.

Minimum fatigue life (dotted lines FIG. 10) and maximum fatigue life (solid lines FIG. 10) are presented and indicate a great improvement in fatigue for ECAE processed Al 2618 as compared to conventional Al 2618 in T6 condition. For maximum fatigue life values, fatigue life is improved by a linear factor 6.5x to 66x. Minimum fatigue life is improved by a linear factor of 7x to 228x. Accordingly, ECAE deformation in combination with heat-treatment provides substantial improvement in fatigue life for a wide range of stresses studied. The increase in tensile strength, hardness and fatigue indicates that wheels comprising Al 2618 processed in accordance with the invention can be utilized for higher operating pressures and rotating frequencies, and can be utilized in compliance with new environmental regulations. The extra strength affords more flexibility in the design of a given piece for a desired fatigue life of a part. These results indicate that Al 2618 processed in accordance with the invention can be used in place of Ti alloys for compressor wheels in particular applications.

EXAMPLE 3

Heat-Treatable Al 2219

The aluminum alloy material designated Al 2219 is a more heavily alloyed material than either Al 2618 or Al 6061. Copper is its principle alloying element and has a nominal presence of 6.3%, which is greater than the standard solubility limit of copper in pure aluminum (around 4.5%). For this alloy, treatment in accordance with the invention was found to be most beneficial when hot ECAE step(s) were conducted before solutionizing and quenching thereby increasing the amount of copper in solution prior to precipitation as explained above. Referring to FIG. 12, such presents results of processing of this alloy in accordance with the invention. FIG. 12 shows the results of equal channel angular extrusion alone, or as combined with solutionizing and post deformation annealing, on the yield strength and ultimate tensile strength relative to standard Al 2219 in the 0 temper condition and peak aged (T6) condition. As shown, a significant strength increase is obtained utilizing combination of solutionizing, equal channel angular extrusion and post deformation annealing relative to ECAE alone, and relative to precipitation strengthening alone (T6 material). As compared to commercially available T6 grade Al 2219, material processed utilizing solutionizing/ECAE/annealing results in a 47% increase in yield strength.

In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred 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.

Claims

1. A high-strength engine component comprising a material consisting of an alloy containing a base metal alloyed with less than or equal to 30% of alloying elements, by weight, the material having an average grain size of less than or equal to about 30 micron, an absence of voids and inclusions having a size greater than 1 micron, and a yield strength at least 50% greater than the yield strength of the identical alloy composition in the annealed 0 temper condition.

2. The high-strength engine component of claim 1 wherein the average grain size is less than or equal to 1 micron.

3. The high-strength engine component of claim 1 wherein the yield strength is at least 100% greater than the yield of the identical alloy in the annealed 0 temper condition.

4. The high-strength engine component of claim 1 wherein the material has a fatigue life at least 5% greater than the fatigue life of the identical alloy composition in the annealed 0 temper condition.

5. The high-strength engine component of claim 4 wherein the material has a fatigue life at least 20% greater than the fatigue life of the identical alloy composition in the annealed 0 temper condition.

6. The high-strength engine component of claim 1 wherein the base metal is selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd.

7. The high-strength engine component of claim 1 wherein the alloy comprises at least one of Al, Ti, Mg, Be, Ni, and Fe.

8. The high-strength engine component of claim 1 wherein the alloy is an Al alloy selected from the group consisting of 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series and 7xxx series Al alloys.

9. The high-strength engine component of claim 1 wherein the alloy is an Al—Li alloy.

10. The high-strength engine component of claim 1 wherein the alloy is a Ti—Al—V alloy.

11. The high-strength engine component of claim 1 wherein the base metal is Mg.

12. The high-strength engine component of claim 1 wherein the engine component is a wheel.

13. A high-strength engine component comprising a material consisting of an alloy containing a base metal alloyed with less than or equal to 0% of alloying elements, by weight, the material having an average grain size of less than or equal to about 30 micron, an absence of voids and inclusions having a size greater than 1 micron, soluble second phase precipitates having an average size of less than 30 micron, and a yield strength at least 10% greater than the yield strength of the identical alloy composition in the T6 temper condition.

14. The high-strength engine component of claim 13 wherein the material has a yield strength at least 30% greater than the yield strength of the identical alloy composition in the T6 temper condition.

15. The high-strength engine component of claim 13 wherein the material has a fatigue life at least 5% greater than the fatigue life of the identical alloy composition in the T6 temper condition.

16. The high-strength engine component of claim 13 wherein the base metal is selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd.

17. The high-strength engine component of claim 13 wherein the alloy comprises at least one of Al, Ti, Mg, Be, Ni, and Fe.

18. The high-strength engine component of claim 13 wherein the alloy is an alloy selected from the group consisting of 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, and 7xxx series Al alloys, Al—Li alloys, Ti—Al—V alloys and Mg based alloys.

19. A vehicle structural component comprising a material consisting of an alloy comprising at least two elements selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd, the alloy containing a base metal alloyed with less than or equal to 10% of additional alloying elements, by weight, the material having an average grain size of less than or equal to about 30 micron, an absence of voids and inclusions having a size greater than 1 micron, and a yield strength at least 50% greater than the yield strength of the identical alloy composition in the annealed 0 temper condition.

20. The vehicle structural component of claim 19 wherein the alloy is an alloy selected from the group consisting of 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, and 7xxx series Al alloys, Al—Li alloys, Ti—Al—V alloys, and Mg-based alloys.

21. The vehicle structural component of claim 19 wherein the structural component is a body panel.

22. A vehicle structural component comprising a material consisting of an alloy comprising at least two elements selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd, the alloy containing a base metal alloyed with less than or equal to 30% of additional alloying elements, by weight, the material having an average grain size of less than or equal to about 30 microns, an absence of voids and inclusions having a size greater than 1 micron, soluble second phase precipitates having an average size of less than 30 micron, and a yield strength at least 10% greater than the yield strength of the identical alloy composition in the T6 temper condition.

23. The vehicle structural component of claim 22 wherein the alloy is an alloy selected from the group consisting of 2xxx series, 3xxx series, 4xxx series, 5xxx series, 6xxx series, and 7xxx series Al alloys, Al—Li alloys, Ti—Al—V alloys and Mg based alloys.

24. The vehicle structural component of claim 22 wherein the structural component is a body panel.

25. A method of producing an engine component comprising:

providing a cast alloy;

performing an initial treatment comprising at least one of thermo-mechanical processing and solutionizing to form a billet;

subjecting the billet to at least one pass of equal channel angular extrusion; and

annealing the extruded billet for at least 30 minutes at a temperature of less than or equal to 0.85 Tr, where Tr is the minimum temperature for which a 30 minute anneal of the extruded billet will produce growth of grains to over 1 micron.

26. The method of claim 25 wherein the initial processing further comprises performing at least one pass of equal channel angular extrusion utilizing heated extrusion die prior to any solutionizing and quenching.

27. The method of claim 26 wherein the heated extrusion die are at least 250° C.

28. The method of claim 25 wherein the alloy comprises one or more elements selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd.

29. The method of claim 25 wherein the alloy comprises a base metal selected from the group consisting of Al, Ti, Mg, and Be.

30. The method of claim 25 wherein the alloy is a heat treatable alloy.

31. The method of claim 30 wherein the initial treatment comprises solutionizing sufficiently to dissolve all soluble second phases followed immediately by quenching.

32. The method of claim 31 further comprising maintaining the billet at a temperature of less than or equal to about 0° C. after quenching.

33. The method of claim 31 further wherein the at least one pass of equal channel angular extrusion is a plurality of passes, and further comprising quenching the billet between each of the plurality of passes.

34. The method of claim 31 further comprising refrigerating the billet between passes of equal channel angular extrusion.

35. The method of claim 30 further comprising artificial precipitation aging the billet at a temperature below the peak aging temperature of the billet.

36. The method of claim 25 wherein the alloy is a non-heat treatable alloy, and wherein the initial treatment lacks solutionizing.

37. The method of claim 25 further comprising pre-heating prior to subjecting to equal channel angular extrusion.

38. The method of claim 37 wherein the preheating comprises at least one of infrared heating and rapid induction heating.

39. The method of claim 25 further comprising heating the billet between each pass of equal channel angular extrusion.

40. The method of claim 25 further comprising applying a back pressure on the billet during the at least one pass of equal channel angular extrusion.

41. A method of forming a vehicle structural component comprising:

forming a billet comprising a heat heat-treatable alloy, the forming comprising: casting the material; and solutionizing the material;

subjecting the billet to at least one pass of equal channel angular extrusion; and

annealing the extruded billet for at least 30 minutes at a temperature of less than or equal to 0.85 Tr, where Tr is the minimum temperature for which a 30 minute anneal of the extruded billet will produce growth of grains to over 1 micron.

42. The method of claim 41 wherein the alloy is an aluminum based alloy.

43. The method of claim 42 is selected from the 2xxx series of aluminum alloys.

44. The method of claim 41 wherein the alloy comprises one or more elements selected from the group consisting of Al, Ti, Mg, Be, Ni, Fe, Cu, Co, W, Ta, Zn, Ag, Sn, Pb, In, Au, Si, Sb, Mo, V, Sc, Cr, Y, B, Mn, C, Li, P, S, Nb, Zr, Pd, and Cd.

45. The method of claim 41 wherein the forming the billet further comprises at least one of hot forging and rolling prior to the solutionizing.

46. The method of claim 41 wherein the forming the billet further comprises quenching the billet immediately after solutionizing.

47. The method of claim 41 wherein the forming the billet further comprises performing at least one pass of equal channel angular extrusion prior to the solutionizing, wherein at least one of the billet and extrusion die are heated prior to the at least one pass.

48. The method of claim 47 wherein an amount of alloying elements solubilized during the formation of the billet is increased due to the equal channel angular extrusion performed prior to solutionizing.