Title:
METHOD FOR PRODUCING FLAT PRODUCTS MADE OF ALUMINUM ALLOYS
Kind Code:
A1


Abstract:
A method of producing flat products in aluminum alloys comprising:
    • A) cold rolling to a hardened condition:
    • B) applying a short-time ion beam surface treatment; and
    • C) repeating steps A and B until a flat rolled product of a specified thickness is obtained.
      The surface treatment is preferably performed using an ion beam of atomic mass A≧10 amu having a power of between about 20-40 keV and an ion current density of between about 0.1-1 mA/cm2 for from about 5 to about 200 seconds. In the process of irradiation flat products may be continuously and uniformly displaced with respect to the ion beam.



Inventors:
Shkolnikov, Alexsey R. (Sverdlovskaya, RU)
Mozharovsky, Sergey M. (Sverdlovskaya, RU)
Filippov, Aleksey V. (Sverdlovskaya, RU)
Ovchinnikov, Vladamir V. (Ekaterinburg, RU)
Gavrilov, Nikolay V. (Ekaterinburg, RU)
Gushchina, Natalia V. (Ekaterinburg, RU)
Application Number:
12/312827
Publication Date:
02/04/2010
Filing Date:
11/28/2007
Primary Class:
Other Classes:
72/365.2, 72/54
International Classes:
B21B1/00; C21D1/26; B21D31/00; C21D8/02
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Primary Examiner:
WALCK, BRIAN D
Attorney, Agent or Firm:
Ron Sakach (Richmond, VA, US)
Claims:
What is claimed is:

1. In a process of producing aluminum alloy sheet including a plurality of cold rolling steps and including an intermediate thermal anneal between cold rolling steps when the aluminum alloy sheet becomes sufficiently work hardened as to inhibit further cold rolling, the improvement comprising substituting an ion beam irradiation of the aluminum alloy sheet for the intermediate thermal anneals.

2. The method of claim 1 wherein the ion beam comprises a beam of ions of atomic weight of A≧10 amu having an energy between about 20 and 40 KeV and a current density of between about 0.1 and 1 mA/cm2.

3. The method of claim 2 wherein the ion beam irradiation is carried out for a period of from about 5 to about 200 seconds.

4. The method of claim 3 wherein the cold rolled aluminum sheet is continuously and uniformly displaced with respect to the ion beam during ion beam irradiation.

5. The method of claims 1 wherein the cold rolled aluminum alloy sheet has two opposing surfaces and the ion beam irradiation is performed simultaneously on both sides of the flat product.

6. The method of claim 1 wherein the aluminum alloy sheet comprises an Al—Mg alloy containing from about 5.8 and 6.8 wt % Mg.

7. The method of claim 1 wherein the aluminum alloy sheet comprises an Al—Li—Cu—Mg alloy which contains between about 1.8 and 2.1 wt % of lithium.

8. The method of claim 1 wherein the aluminum alloy sheet comprises an Al—Cu—Mg alloy that includes Mn additives.

9. The method of claim 1 wherein the ion beam comprises a beam of Ar+ ions.

10. The method of claim 2 wherein the ion beam comprises a beam of Ar+ ions.

11. The method of claim 3 wherein the ion beam comprises a beam of Ar+ ions.

Description:

FIELD OF THE INVENTION

The present invention is related to aluminum metallurgy, and more particularly to a novel method for alleviating the hardened (cold worked) condition that requires stress relieving and structure improvement during conventional processing.

BACKGROUND OF THE INVENTION

The role of aluminum alloys as structural materials is constantly increasing. In addition to commercial pressures to improve the physical properties of aluminum alloys, recent adverse economic conditions have imposed additional pressures on reducing production costs.

One of the most labor intensive and power consuming operations in the manufacture of flat rolled aluminum alloys are those operations related to the necessity to relieve the hardened (cold worked) condition originating in the course of cold rolling. Hardening or cold working in this context describes a condition wherein flat rolled aluminum hardens in the course of cold rolling. This hardening results in ductility reduction that makes further rolling impossible. In order to eliminate this phenomenon flat product is typically subjected to heat treatment in a specified range of temperatures intermediate the various individual rolling procedures.

A conventional method for producing flat rolled aluminum alloys is described in Structure and Properties of Semi-Finished Products in Aluminum Alloys. Reference book ed. by V. A. Livanov, Moscow, “Metallurgiya”, Page 85, 1974. This process includes cold rolling to the hardened condition and heat treating (intermediate annealing), as these steps are repeated to produce flat rolled products of a required thickness. Anneals are carried out at temperature of 310-335° C. According to this method the best anticorrosion properties are provided by slow heat up through the annealing cycle and subsequent slow cooling. Annealing is achieved by placing coils or stacks of cut aluminum alloy sheets into an annealing furnace for heat treatment. Such handling results in the consumption of large amounts of time and power consumption that translate into high costs of production. One of the most labor intensive steps during performance of these annealing operations is the removal of rolled coils from the hot rolling mill, coil transportation and placement into and removal from the annealing furnaces. The smaller the gauge of the flat rolled product being produced, the larger the number of anneals required.

The obvious disadvantages of this method are the high labor cost and energy intensiveness of the process. Another less apparent disadvantage relates to the impossibility eliminating some intermetallic compounds that originate in the course of annealing, for example the formation of Al6 (Fe, Mn). The existence of coarse intermetallic compounds such as Al6 (Fe, Mn) in the alloy structure negatively influences the properties of the cold rolled material, in particular, it reduces its ductility.

A method of producing cold-work parts from the following alloy composition is known (A 2001124821, MPK7, B22F3/24, C21D1/26, C21D7/02, C22F1/10, C22F1/18).

This method used for the processing of alloys chosen from those of iron, nickel, and titanium aluminides, includes the following steps:

(a) producing a part, which is hardened by metallic alloy composition hardening to such an extent, that a face-hardened zone is created on it;

(b) heat treating the face-hardened part by heating in a furnace in such a way, that it is instantaneously annealed in less than one minute;

and optionally (c)—reiteration of steps (a) and (b) until a part of a specified gauge is produced.

One of the variants of this method includes instantaneous annealing by heating the hardened part with infra red (IR) radiation.

Hardening is induced by cold rolling, and hardened parts, in particular, sheets, strips, extruded rounds or strip profiles or wires are treated in accordance with this technique. The step of instantaneous annealing consists of heating the hardened part to a temperature of at least 400° C. during of minimum 45 sec. using IR radiation.

Though heating and holding in a furnace according to this prior art method takes less than one minute, parts must still be delivered to the furnace, where the high temperature must be maintained to realize instantaneous heating. All of these steps incur expenditures of time, labor, and electric power.

In the course of this prior art process the hardened condition is relieved only in the face-hardened zone, and it is also impossible to eliminate the formation of some intermetallic compounds such as, Al6(Fe, Mn) in the application of this prior art process to more conventional aluminum alloys.

Thus, there remains a need for a method for the elimination/alleviation of cold work during cold rolling that is more cost effective than the prior art annealing processes that require large expenditures of time, labor and heat energy to achieve.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide a method for annealing or relieving cold work in the course of processing aluminum flat rolled or otherwise processed products that eliminates the costly thermal annealing steps of the prior art.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a method of producing flat products in aluminum alloys comprising:

A) cold rolling to a hardened condition:

B) applying an ion beam surface treatment to relieve cold work induced hardening; and

C) repeating steps A and B until a flat rolled product of a specified thickness is obtained.

The surface treatment is preferably performed using an ion beam of atomic mass A≧10 amu having a power of between about 20-40 keV and an ion current density of between about 0.1-1 mA/cm2 for from about 5 to about 200 seconds. In the process of irradiation flat products may be continuously and uniformly displaced with respect to the ion beam. Aluminum alloys of the Al—Mg system, which contain 5.8-6.8 wt % Mg (so-called, magnaliums), the Al—Cu—Mg system containing Mn additives (duralumins) and the Al—Li—Cu—Mg system with lithium contents of 1.8-2.1 wt % are particularly, but not exclusively, susceptible to the annealing practices described herein.

DETAILED DESCRIPTION

According to the present invention, irradiation is conducted by an ion beam with a power of 20-40 keV, an ion current density of 0.1-1 mA/cm2 for from about 5 to about 200 seconds. In the process of irradiation flat products may be continuously and uniformly displaced with respect to the ion beam. Surface irradiation may also be carried out simultaneously from two sides.

The chemical composition of some, but not all, susceptible aluminum alloys (wt %) are presented in Table 1 below.

TABLE 1
SiFeCuMnMgZnTiLiBeZrNi
VD1
0.7-1.20.71.8-2.60.4-0.80.4-0.80.30.1
1441
0.080.121.5-1.80.001-0.10 0.7-1.10.01-0.071.8-2.10.02-0.200.04-0.160.02-0.1
AMg6
0.1 0.1<0.10.696.4<0.10.040.0008

The duration of ion beam irradiation is specific to alloy composition, processed sheet thickness, and is affected by whether the sheet is treated on one or two sides. In addition, it is important to note that the time of irradiation necessary for obtaining appropriate treatment depends on ion beam current density. The higher ion beam current density, the shorter the time of irradiation.

Results for stationary and uniformly moving flat product strip are absolutely identical given identical irradiation parameters.

The present method differs from prior art thermal annealing practices, as well as from past ion-beam treatments in the fact that it uses a radiation-dynamic action by accelerated ions instead of normal heat treatments or ion alloying processes that can induce radiation damage.

In this context, it is noted that ion beams of low and medium energy ions (from several units to several hundreds of keV) have been used for the purpose of surface alloying (ion penetration into layers with thicknesses from several tens to several hundreds of nm), and also to establish highly defective (strongly nonequilibrium—up to amorphous) conditions in surface layers of the same thickness allowing: increases in corrosion resistance; enhancement of microhardness; wear resistance; as well as modification of some other surface properties of materials (Surface Modifying and Alloying by Laser, Ion, and Electric Beams, a digest edited by J. M. Pote et al., translation from English edited by A. A. Uglov, M., “Mashostroyenie”, p. 424, 1987; Effects of Long-Range Action in Ion-Implanted Metallic Materials, A. N. Didenko et al., Tomsk, NTL Publishing House, p. 328, 2004). These processes do not produce the annealing effects described herein, but rather induce alternative surface modifications as just described, and are not used to anneal material that has achieved a hardened or cold worked condition.

Accumulation of high-static stress solids in surface layers from implanted admixtures (by large radiation doses of more than 1017 cm−2), as practiced in the prior art, allows modifying surface layers up to a depth of several tens of microns at the expense of formation of new dislocations and movement of existing dislocations deep into the substance.

We have found that exposure of aluminum alloys to high energy ion beams initiates deeply self-propagating structural phase transformations thereby altering the structural properties of these materials to depths tens and even hundreds of thousands of times deeper than the depth of penetration of accelerated ions impacted with and into the surface thereof. These effects are apparently stimulated by the formation and propagation of microshock waves formed as the result of atomic displacement/compact cascades caused by ion beam irradiation.

Experimentation indicates that irradiation with ions with atomic mass A≧10 amu, but lighter than argon, induce similar action on the structure and properties of aluminum alloys, though rather weaker than those induced by argon. Using ions in the range of A<10 amu, the density of the energy emitted by the atomic collisions, and, concomitantly, the intensity of radiation-dynamic effects of the ion beams on the structure and properties of the treated aluminum alloys, substantially decreases.

Application of the method of the present invention to an aluminum alloy comprising Al-4 wt % Cu indicates that the particular ion used in irradiation (for example, Ar+, Al+ or Cu+) has relatively no influence on the structural and phase composition changes induced by the ion irradiation described herein. Thus, selection of the specific heavy ions used for irradiation is not critical. Utilization of inert gas ions, in particular, Ar+, guarantees lack of any secondary effects on surface chemical properties and thus use of this ion is specifically preferred.

Lower energy ion beams have been used to clean surfaces of materials of oxides and adsorbed admixtures due to the effects of cascade and thermal sputtering of surface atoms by ions of lower energies (typically 5-10 keV). Ions with energies of 10-20 keV and more, having greater depth of penetration into the substance, are used for ion-beam modification of, for example, the surfaces of construction materials. The upper limit of beam energies used (typically 40-50 keV) is determined by the necessity to restrict the temperature of materials under treatment, (in the case of aluminum alloys, a maximum 450° C.). In addition, the design of industrial ion accelerators (ion sources), where portability (small sizes) is a requirement, generally dictates ultimate voltages that do not exceeding 40-50 keV.

The range of useful ion current densities has been determined, on one hand, by the fact that with j<0.05-0.1 mA/cm2 (50-1000 mA/cm2) radiation-dynamic effects are generally insufficient to induce the desired effects. On the other hand, utilization of currents of more than 1 mA/cm2 result in virtually instantaneous (within several seconds) heating of the aluminum alloy flat product areas exposed to the radiation, and can result in melting of the surface of the material.

The results of mechanical testing of specimens cut out of initially hardened, annealed, and irradiated rolled sheets are shown in Table 2 below confirm the results previously discussed, namely the relatively deep alteration of the properties of these materials by ion beam treatment as described herein. Electron microscope images of the structures of sheets of different aluminum alloys obtained after hardening, annealing, and ion-beam treatment (not shown) confirm these results.

TABLE 2
Mechanical properties and structure of sheets in industrial aluminum
alloys AMg6, 1441, and VD1 after different types of treatment
Alloy
AMg61441VD1
Types ofσB,σ0.2,δ,σB,σ0.2,δ,σB,σ0.2,δ,
treatmentMPaMPa%StructureMPaMPa%StructureMPaMPa%Structure
Hardening4454079.6cellular315.52963.3cellular2552466.5cellular
Industrial32817828grained24513420grained7659grained
annealing
(within 2
hours)
Ar+ ion-33518228grained21813019grained1058143grained
beam
treatment

Example 1

Performance of ion-beam treatment in the rolling Al—Mg alloy sheet (so-called, magnaliums).

After the rolling of an AlMg6 until alloy hardening/cold work makes further rolling impossible. The surface of the rolled sheet is irradiated with Ar+ ions having an energy of 40 keV, and an ion current density of 400 mA/cm2. The sheet has a thickness of 4 mm and is irradiated from both sides for a period of 30 seconds

In the course of irradiation continuous monitoring of target temperature is carried out by means of a chromel-alumel thermocouple. The ultimate temperature, to which sheets are heated within the short course of irradiation, does not exceed 400° C.

Mechanical testing of tensile specimens cut out from hardened, annealed, and irradiated sheets was performed at Kamensk Uralsky Metallurgical Works J.S.Co. These tests show that as a result of ion irradiation, irrespective of specimen temperature, ductility increases due to a substantial decrease in alloy/sheet strength. The results of the mechanical testing of initial and irradiated specimens in alloy AMg6 are given in Table 2. It is obvious that the mechanical properties of sheets after ion-beam treatment are close to the properties obtained by thermal annealing.

Electron microscope examinations have been carried out on specimens cut out parallel and perpendicularly to the irradiated surfaces. These examinations have allowed determination that structural changes (reduction of dislocation density, formation of sub-grained, grained crystalline structures) and phase transformations (dissolution and formation of intermetallic phases) initiated by ion irradiation take place throughout the specimen depth.

Electron microscope pictures of hardened alloy AMg6 show cellular structures with wide borders between individual cells of a of diameter is 1-2 μm. Large concentrations of round or ellipsoidal intermetallic compounds Al6(Fe, Mn) caused by crystallization and with average diameter of ˜0.5-1 μm are present in the alloy.

Annealing of cold-worked alloy AMg6 at temperatures 310-325° C. for less than 2 hours results in the formation of a uniform re-crystallized structure with grain sizes of greater than 10 μm It is noted that after thermal annealing the alloy retains large amounts of coarse intermetallic compounds Al6(Fe, Mn) of crystallization origin. Similar compounds have been observed in the initial cold rolled and hardened condition.

After ion-beam treatment a coarse-crystalline grained structure is observed in the alloy. This structure is the same as that observed after thermal annealing as described above. In addition, after ion-beam treatment a reduction in the amount of intermetallic compounds Al6(Fe, Mn) which can negatively influence the ductility of the alloy is noted.

Thus, a direct comparison of the structural and mechanical properties of alloy AMg6 after thermal annealing and ion-beam treatment shows that short-term ion beam irradiation results in the formation of a re-crystallized structure that is similar to the structure obtained as the result of intermediate thermal annealing. Such re-crystallization results in a reduction in strength and a concommitant increase in ductility, i.e. relief of cold work.

Thus, the ion-beam treatment for sheets in aluminum alloy AMg6 allows described herein completely relieves cold work and internal stresses arising in the course of cold rolling. Additionally, improvement of flat product structure is observed due to a decrease in the amount of intermetallic compounds Al6(Fe, Mn) present that can negatively influence the ductility of the alloy.

Example 2

Performance of ion-beam treatment in the course of rolling sheets in aluminum alloy 1441 of system Al—Li—Cu—Mg with lithium content of 1.8-2.1 wt %.

After cold rolling to the point that further rolling is impossible (a thickness of about 1.0 mm), instead of applying a conventional intermediate annealing at T=380-420° C. for 2 hours, both surfaces of a sheet in alloy 1441 are irradiated with Ar+ ions having an energy of 40 keV, with ion current density of 400 mA/cm2.

The results of mechanical testing of initially hardened, thermally annealed, and irradiated specimens show that the mechanical properties of sheets in alloy 1441 after ion-beam treatment are close to the properties obtained by intermediate thermal annealing (Table 2). Irregular cellular dislocations with cell central area average diameters of from 0.5 to 2 μm are found in hardened alloy 1441.

After thermal annealing at temperatures 380-420° C. for 2 hours the structure of alloy 1441 is irregular: there is a co-existence of grains with diameter 1-2 μm, inside of which high density of dislocations are retained, and equiaxed re-crystallized grains with average diameters of 10 and more μm that are free of dislocations. The fraction of the latter is about 70% of specimen volume.

Thus, ion irradiation results in the formation of a uniform coarse-crystalline grained structure with grain diameters of 10 μm. A similar structure is typical for alloys in the re-crystallized (thermally annealed) condition

Thus, as in the preceding example, the results of mechanical testing and electron microscope examination of alloy 1441 sheet structure shows that short-term treatment of work hardened flat product surfaces with an Ar+ ion beam results in complete cold work relief throughout sheet thickness.

Example 3

Ion-beam treatment in the course of rolling sheets in aluminum alloy VD1 (Al—Cu—Mg with Mn additives with reduced content of all components (duralumin of increased ductility).

After cold rolling to a point where alloy hardening makes further rolling impossible instead of conventional intermediate annealing both surfaces of a VD1 alloy sheet having a thickness of 1.5 mm are irradiated for 30 seconds with Ar+ ions having an energy of 40 keV, with an ion current density of 400 mA/cm2.

The results of mechanical testing of cold work hardened, thermally annealed, and irradiated specimens of alloy VD1 show that after ion-beam treatment a substantial decrease in strength is observed. This loss decrease in strength approximates that obtained by intermediate thermal annealing (see Table 2).

Electron microscope examination of cold-worked alloy VD1 indicates the presence of a dislocation grained structure with narrow borders between individual cells. Cell diameter is 0.5-2 μm.

After two-hours thermal annealing at temperatures of 240-250° C. a practically uniform sub-grained structure with sub-grain average diameters of 0.5-2 μm is formed in the alloy VD1 sheet.

After irradiation a crystalline structure with grain sizes of more than 10 μm is found in the alloy. Also, in the course of irradiation, decomposition of the solid solution occurs with the release of a high concentration of equiaxed phase θ′(θ″) (CuAl2) particles with diameters from 10-20 μm.

The oversaturated solid solution decomposition processes that occur simultaneously with re-crystallization under ion irradiation do not impede alloy strength decrease-despite the release of a high concentration of the uniformly distributed strengthening phase. The mechanical properties obtained are similar to those obtained through intermediate thermal annealing.

Thus, as shown in the foregoing examples, the method of the present invention differs significantly and advantageously from those of the prior art.

Significant advantages of the present invention are that it provides a method of producing flat products in aluminum alloys in a continuous cycle, without process shutdowns, significantly reduces process energy and labor intensity, and also reduces process cycle time.

A further advantage of the present invention is that during cold working of aluminum products cold work relief can be achieved not only in surface layers but also throughout the thickness of the material. The treatment process of the present invention alters not only the hardness of the surface layers of the material, but also in induces changes in the macroscopic mechanical properties, such as tensile strength, yield strength, and elongation (see Table 2), of the entire material volume. This results not only in the elimination of hardening, but also in flat product improvement by means of the dissolution of coarse intermetallic compounds that can negatively influence properties and may not be dissolved during conventional thermal annealing.

A plasma ion emitter (S 1 No. 2045102, MPK6 H01Y27/04), hereinafter referred to as the ion source, has been used to accomplish the claimed method. The ion source contains a hollow cylindrical cathode, where one of its ends has a multi-aperture emission window opening, and a pin anode is installed coaxially with the cathode at the other end by means of a feedthrough insulator. A pin solenoid creating a magnetic field in the B cavity is installed at an external side of the cathode coaxially with the cathode.

A glow discharge generates plasma with high spatial homogeneity in the cathode cavity. Ions are extracted from the plasma along the magnetic field through openings in the cathode end. A heavy-gage beam (>100 cm2) of circular or band cross-section subject to electrode shape is formed by the two-electrode multi-aperture electrostatic ion-optical system.

After actuation gas puffing (10-30 cm3/min) into the ion source and creation of a weak magnetic field (5 mT) by an external solenoid with ˜3 kV voltage supply, a glow discharge in the source electrode system is ignited at the intersection of the electric and magnetic fields. The discharge current is controlled within limits of 0.2-1.5 A in a continuous mode of beam generation and 1-10 A in a pulse-periodic mode with current a width of 1 msec and repetition frequency up to 200 Hz.

The ion beam is generated by application of high voltage (up to 50 kV) between the electrodes of the ion-optical system. Beam current control within wide limits is ensured by discharge current monitoring and alteration. In the continuous generation mode, beam current is up to 80 mA, in the pulse-periodic mode at the same average current amplitude beam current may be up to 0.4 A. The pulse-periodic mode ensures a controllable set of small doses of ion irradiation (1013 cm−2 per pulse).

Flat product surface double-sided treatment is carried out by means of two ion beams directed towards each other at the expense of operating two ion sources. The ion source may be as a separate independent device, or as part of the cold rolling mill.

Further examples of the application of the present invention to very specific alloys follow.

Example 4

Production of flat rolled of Al—Mg aluminum alloy.

An aluminum alloy having the composition shown in Table 3 below was treated as described below.

TABLE 3
ComponentSiFeCuMnMgZnTiAl
Content,0.40.30.10.76.350.20.05Remainder
wt %

Ingot cast in the alloy shown in Table 3 is processed to produce a flat sheet having a thickness of 6 mm. This sheet is cold rolled to a thickness of 4 mm. Further cold rolling is difficult due to the cold-worked condition of the sheet. Both sheet surfaces are irradiated with Ar+ ions having an energy of 40 keV, and an ion current density of 400 mA/cm2, by means of the ion source described above. Irradiation is carried out for 22 sec.

During treatment, the sheet is continuously and uniformly displaced with respect to the ion beam, i.e. relative to the ion source. As a result of such treatment the cold-worked condition of the sheet and internal stresses induced during cold rolling are relieved completely.

The sheet is again subjected to cold rolling. Taking into account, that the maximum degree of deformation of sheets by cold rolling for this alloy is 30-35% before onset of the cold-worked condition, on thicknesses of 2.5 mm, 1.5 mm, the sheet is again exposed to intermediate short-term (less than one minute, specifically, 10 and 6 sec.) ion irradiation. Sheet structure and mechanical properties both in the cold-worked condition on thicknesses of 2.5 mm and 1.5 mm, and after cold work relief are similar to the values presented in Table 2.

Final sheet thickness is 1 mm. Thus, flat rolled sheet 1 mm thick is produced as the result of three steps of cold rolling and three short-term (less than one minute) ion irradiations (having replaced 3 intermediate thermal annealing processes in an electric furnace at temperature of T=310-335° C. for 1-2 hours, that are conventionally applied to produce flat product with thickness of 1 mm in alloy AMg6).

Example 5

Producing flat product in aluminum alloy 1441 of Al—Li—Cu—Mg system. The chemical composition of this alloy is given in Table 4.

TABLE 4
ComponentSiFeLiCuMnMgTiZrAl
Content,0.080.121.91.60.050.80.10.1Remainder
Wt %

Ingot cast in the alloy in Table 4 is processed to produce a flat sheet having a thickness of 6.5 mm. The sheet is then cold rolled in a cold rolling mill to a thickness of 1.5 mm. Further cold rolling is impossible at this point due to the cold-worked condition of the sheet.

To relieve this cold-worked condition, both surfaces of the sheet are exposed to irradiation by Ar+ ions having an energy of 40 keV, and an ion current density of 400 mA/cm2 for about 6 seconds. During irradiation, the sheet is continuously and uniformly displaced with respect to the ion beam, i.e. relative to the ion source. As a result of such treatment the cold-worked condition of the sheet and internal stresses caused during cold rolling are relieved completely. The sheet is subsequently cold rolled to a thickness equal of 0.5 mm.

Thus, flat product having a thickness of 0.5 mm is produced in a two step cold rolling process that incorporates one short-term ion irradiation (having replaced intermediate thermal annealing in an electric furnace at a temperature of T=380-420° C. for 2 hours, as conventionally applied to produce flat product with thickness of 0.5 mm in alloy 1441).

Example 6

Production of flat aluminum alloy VD1.

The chemical composition of this alloy is given in the Table 5.

TABLE 5
ComponentSiFeCuMnMgZnNiAl
Content,0.91.03.50.40.60.70.2Remainder
wt %

Ingot cast in the alloy shown in Table 5 is processed using conventional methods to a sheet thickness of 7.0 mm. This sheet is then cold rolled to a thickness of 1.0 mm. At this thickness, further cold rolling is impossible due to work hardening. To relieve this cold-worked condition, both surfaces of the sheet are exposed for 10 seconds to irradiation by Ar+ ions having an energy of 40 keV, and an ion current density of 400 mA/cm2. During irradiation, the sheet is continuously and uniformly displaced with respect to the ion beam. As a result of such treatment the cold-worked condition of the sheet and internal stresses induced during cold rolling are relieved completely.

Thus, flat sheet of VD1 having a thickness of 0.5 mm is produced as the result of two steps of cold rolling and one short-term ion irradiation (having replaced intermediate annealing in an electric furnace at temperature of T=240-250° C. for 2 hours as is conventionally applied to produce flat product with a thickness of 0.5 mm in alloy 1441).

Thus, what has been described is a new and highly productive method of producing flat product in aluminum alloys which method provides significant reductions in energy usage and greatly reduces production expenditures, all while improving the structure and properties of the alloys. Energy consumption for conventional industrial thermal annealing of flat products in aluminum alloys in the course of rolling is estimated at about 396 kWh per 1 MT of metal, while energy consumption by the improved ion beam annealing process of the present invention is estimated at about 123 kWh per 1 MT of metal. This is a significant cost saving even ignoring the time and labor savings previously described.

As the invention has been described, it will be apparent to those skilled in the art that the same may be varied in many ways without departing from the spirit and scope thereof. Any and all such modifications are intended to be included within the scope of the appended claims.