FR2607521A1 - METHOD FOR THE THERMAL TREATMENT OF AL ALLOYS CONTAINING LI AND THE PRODUCT THUS OBTAINED - Google Patents

Abstract

THE INVENTION RELATES TO A FINAL THERMAL TREATMENT (RETURN) METHOD OF AL ALLOYS CONTAINING ESSENTIALLY LI AND AT LEAST ONE OTHER MAJOR ELEMENT BELONGING TO THE CU, MG, ZN GROUP AS WELL AS POSSIBLE MINOR ELEMENTS SUCH AS ZR, MN, CR , NI, HF, TI, BE IN ADDITION TO THE INEVITABLE IMPURITIES SUCH AS FE OR SI. THE TREATMENT INCLUDES A MAIN INCOME (FIG. 1) BETWEEN 215 AND 270 C FOR A FEW MINUTES - A FEW HOURS, POSSIBLE PRECEDED BY A PRE-INCOME AND POSSIBLY FOLLOWED BY AN ADDITIONAL INCOME, UNDER THE CONDITIONS REFERRED TO FIGURES 2 AND 3 RESPECTIVELY . THIS THERMAL TREATMENT ALLOWS A SATISFACTORY SET OF MECHANICAL CHARACTERISTICS: MECHANICAL RESISTANCE, DUCTILITY OR TENACITY AND CORROSION RESISTANCE, SUPERIOR THAN THOSE OBTAINED USING CLASSIC TREATMENTS TYPE T6 OR BY SUBREVENUS QU'UNE, ISOTROPY OF MECHANICAL CHARACTERISTICS.

Description

METHOD FOR THERMALLY TREATING ALLIACES BASED ON A1

  The invention relates to a method for final heat treatment (tempering) of Al alloys containing essentially lithium and at least one other major element belonging to the group Cu, Mg, Zn, as well as minor elements such as Zr, Mn, Cr, Ni, Hf, Ti, Be, in addition to unavoidable impurities such as Fe or Si and the product thus obtained. The problem solved by the invention is that of obtaining, for the alloys designated above, mechanical characteristics in the cross direction (elastic limit, load, rupture and elongation), impact resistance, toughness, resistance to corrosion (intergranular and under tension) improved, as well as a better isotropy of the mechanical properties, compared to those of these same alloys treated conventionally (maximum hardening income or sub-income), using a treatment specific income, despite

  unsuccessful attempts reported below.

  Indeed, despite their attractive characteristics with regard to low density, their high elastic modulus and their good mechanical resistance, Al alloys containing Li generally have either a poor tolerance to damage (low ductility and toughness), or poor corrosion behavior (intergranular or under tension), compared to conventional Al alloys (series 2000 or 7000 according to the designation of the Aluminum Association), having a substantially equivalent mechanical strength. In addition, the anisotropy and heterogeneity of mechanical properties on non-recrystallized products is a recognized disadvantage of Al-Li alloys in view

of their use.

  This low ductility has been reported in particular by EA STARKE et al (Journal of Metals, Aug. 1981, pages 24-32) which advocates a number of solutions to this problem, such as: - use of substantially pure materials of high purity Na, P, S, H2; use of rapid solidification, powder metallurgy, thermomechanical treatments, to obtain grain products

  fine and / or non-recrystallized structures and fine precipitation.

  However, these methods are complex, time consuming and relatively expensive. It is recognized by metallurgists that the sub-yield of Li-hardened structural hardenings leads to the best compromise of mechanical strength and ductility or toughness, at the cost of poor intergranular corrosion resistance and corrosion. under tension in the cross direction and a great anisotropy

properties.

  Over-income leads to a decrease in the mechanical resistance by coalescence of the metastable phase C '(A13Li) in the matrix and also to a decrease of the elongations and the tenacity by the widening of the stripped zones in metastable phase C' ( A13Li)

at the grain boundaries.

  I.G. PALMER et al., Al-Li Alloys II, Conf. Proceeding Met. Soc. AIME Montenay, 1983, April 12-16, Ed. By A. STARKE Jr and T. H. SANDERS p. 105. This last phenomenon is also encountered in the over-incomes of Al-Li alloys containing Cu and / or Mg. These then have a phase C 'precipitation in the matrix always accompanied by the coprecipitation of phases such as T'1 or T1 (A12CuLi) in the form of platelets, T'2 or T2 (A16CuLi3) in the form of rods, the phase

  S 'or S (A12CuMg) in the form of needles or slats and A12LiMg.

  But unlike conventional alloys (series 2000 and 7000) these surcharges do not lead to good resistance to corrosion

under pressure.

  The final heat treatments used up to now on all known industrial or experimental alloys based on Al and containing Li thus consist of single-turn incomes at 170-190 C type T6 (for obtaining the maximum of mechanical strength) or subrevenue (to improve the compromise load of rupture-elongation

or tenacity).

  The heat treatment of Al-Li alloys (Cu-Mg-Zn) according to the invention, which makes it possible to avoid all these drawbacks, comprises at least one dissolution in solution followed by quenching, possibly a plastic deformation between 0.5 and 5%, a maturation and finally at least one income that we will designate by principal income. The latter is carried out in a temperature range between 215 and 270 C for a period of between 3 minutes and 16 hours; the preferred range is between 220 and 260 ° C. for times of between 5 minutes and 12 hours, the highest temperatures being

  usually associated with the shortest time.

  More precisely, the main income must be made in a parallelogram temperature-time domain whose vertices, on a temperature (C) -log time plot, have the following coordinates A 270 C - 3 min B 270 C - 48 min C 215 C - 16 h D 215 C - 1 h and preferably E 260 C - 5 min F 260 C - 120h G 220 C - 12 h H 220 C min

  The temperature of the main income, when it is isothermal,

  depends on the effective chemical composition of the alloy and is preferably between -10 C and To +25 C, with: To (C) = 65 + 80 (% Li) + 5 (% Mg) + 1.5 (% Zn),

  the percentages being by weight, with preferably 1.7 <% Li <2,6-

  0.2% <Cu <3.4% - Mg, 7.0 and% Zn <3%.

  It should be noted that To is independent of the copper content of

the alloy considered.

  However, this duration must be sufficient to dissolve the virtual

  all of the spherical phases 4 'A13Li previously formed (for example during cooling after quenching, during maturation and / or during the rise in temperature during the main income), with the exception in general of the coarse phases C' surrounding the dispersed particles of the globular A13Zr phases (as evidenced by GAYLE and VANDER SANDE - Scripta Metall, Vol 18, rl984, pp. 473-478) or else rare coarse particles of phase J '

  (> 25 un) dissolved at the temperature of the main income.

  From the structural point of view, after the income and outside the undissolved particles, the structure comprises a fine dense precipitation of spherical C 'phases whose maximum size is less than nm (and preferably less than 5 nm) formed during the

  cooling after the main income.

  These globular phases i 'are then accompanied by at least one

  conventional hardening phases: S 'or S - A12CuMg, T'1 or T1 -

  A12CuLi, A12MgLi, T'2 or T2 A16CuLi3 depending on the chemical composition of the alloy, these being also in the form of needles

  platelets, slats or sticks in the matrix.

  Excessive temperatures or durations of the main income lead to a loss of mechanical strength associated with a decrease in ductility, toughness or impact resistance. In contrast to insufficient temperatures or times lead to poor resistance to intergranular or stress corrosion and to less

good isotropy.

  The main income may be preceded by a maturation or a pre-

  returned at a temperature below 200 C and for a period at most equivalent to that corresponding to the T6 state of the alloy in question, which makes it possible to increase the characteristics of mechanical strength and corrosion, without significant loss of ductility, especially for

the alloys loaded with Cu.

26C7521

  The duration of this pre-income (t ') is limited in a temperature diagram (C) - log time (in hours) by the right

equation O = -60 log t'M + 260.

  This pre-income is preferably in the range of temperature ranging from 120 to 180 C for a minimum duration t'm corresponding to the formula:

  0 (C) = 180 - 60 log um (in hours).

  Mechanical strength and corrosion resistance can still

  be improved by preceding the main income (or the pre-

  yield) of a plastic deformation of between 0.5 and 5%, generally carried out by planing, traction or controlled compression,

stretching, rolling, etc.

  After main revenue, the products have: - moderately high mechanical strength characteristics equivalent to those of the 2024 T351 and which allow either a hardening or hardening by hardening without risk of rupture,

  or intermediate operations of straightening, planing, etc ...

  corresponding to a plastic deformation of between 0.5 and 5%.

  - high tensile elongations.

  - Particularly high necking, especially when the main income is preceded by hardening after tempering on alloy containing

phase S or S '.

  a good homogeneity of the mechanical properties of the thick products.

  a good isotropy of the mechanical characteristics.

  - Good resistance to surface (EXCo test), intergranular corrosion (AIR 9048 standard) and improved resistance

  stress corrosion with respect to the T6 or sub-

  returned. an appreciable attenuation of the undesirable laminated fracture facies. - better impact resistance than in the under-tempered state of equivalent hardness. equivalent.

26075 1

  The level of the mechanical characteristics as well as the resistance to intergranular corrosion or its stresses are further improved by a supplementary income made at a temperature (O) lower than that of a main income and between 170 and 210 ° C. duration tm greater than 0 (C) = 230-66 log tm (hours) and less than 60 hours. The temperature is preferably between

and 205 C.

  Too short durations and / or too low temperatures lead to excessive brittleness without substantially improving the corrosion resistance in the raw state of main income and too long durations and / or too high temperatures lead to increased brittleness due to excessive precipitation of intergranular Li-rich phases and correlative expansion of zones

stripped in phase '.

  Under these conditions, the size of the spherical phase J 'is greater than or equal to 10 nm or it is precipitated in elongated or semicircular form at the interface between the phases T'1 or T1, S' or S and

the matrix of Al.

  The additional income can be made either separately or in continuous cooling after the main income. In the first case, it is possible to perform a cold work hardening between the 2 incomes between 0.5 and 5% so as to increase the level of

  mechanical characteristics and corrosion resistance.

  The invention will be better understood using the examples described below and illustrated by the following figures: 30. FIG. 1 represents the general (ABCD) and preferential (EFGH) domain of the temperature-time conditions of the main income in

  coordinates: temperature in C - log time in hours.

  FIG. 2 represents the limit (L /) of the pre-income as well as the preferential domain (A'B'C'D ') thereof in coordinates: temperature

in C - log time in hours.

  FIG. 3 represents the general domain and the preferential domain (A "B" C "D") of the conditions of the complementary income in coordinates:

  temperature C - log time in hours.

Example 1

  Flats of section 100 x 13 mm in alloy 2091 (Li = 2.0%, Cu 2.0% Mg = 1.4% - Zr = 0.11%, Fe + Si = 0.06%), have undergone after dissolving (2h 530 C), quenching and controlled pulling by 2% (where applicable), either conventional income (under T6 or T651 income or income) or 240 C main income treatments according to the invention. Some treatments were preceded by a pretreatment treatment in a ventilated air oven. All major incomes were made in a nitrite-nitrate salt bath and were followed

cooling with water.

  The flats had a non-recrystallized structure.

  Table 1 gives the mechanical tensile characteristics (average of 2 specimens taken at mid-width of the flat in the longitudinal direction or in all the width in the transverse direction = elastic limit at 0.2% of remanent deformation (RpO, 2) , tensile strength (Rm), elongation at break (A%) and necking (7%) measured on specimens The sensitivity to intergranular corrosion measured at the core and gross surface of the larget is also given after the test according to the standard AIR 9048 (continuous immersion in aqueous solution

NaCl + H2O2).

  The results show that the main income according to the invention, whether or not preceded by a precursor, leads, on alloy 2091, to a higher level of mechanical strength and ductility, in the cross direction, to that of the sub-components. conventional incomes and close to that of conventional income at the peak of hardening (T6, T651). It also leads to a very clear improvement in the resistance to intergranular corrosion at the core and at the surface of the products, as well as an excellent isotropy of the mechanical properties, obtained at the cost of

  slight decrease in mechanical resistance in the long direction.

  In addition, the largets treated according to the invention had in the raw state of principal income a very high necking, especially in case 8 260 jr 5 2 I controlled traction after quenching, indicating the excellent ductility of the product. This is much higher than that of all the under-income states or that of the T6 or T651 states. In addition, the largets characterized in the raw state of main income had an almost total absence of longitudinal secondary cracking on rupture test pieces (ie no noticeable tendency to laminated rupture). The diameter of the λ-Δ13Li phases in the matrix, measured at high magnification with the transmission electron microscope, was less than 4 nm for all the particles except for some composite particles of phase - A13Li surrounding the spherical particles.

  phase A13Zr (diameter approximately 40 nm).

Example 2

  Thick rolled 38.5 mm 2091 alloys were subjected to dissolution from 2h30 to 530 C followed by a 2% contraction controlled pull of residual strain and conventional incomes (under- or over-inflated), as well as main income treatments according to the invention, all carried out in ventilated air oven with air cooling, so as to give average levels of mechanical strength

comparable to each other.

  Table 2 gives the mechanical tensile characteristics (Rp 0.2, Rm, A%) measured respectively at mid-thickness in the long direction, through long, at 60 in the long direction (direction usually low in this type of product), as well as in the cross-court direction. The behavior in intergranular corrosion is also given after continuous immersion in 3% NaCl + H 2 O 2 solution, according to the standard

aeronautical AIR 9048.

  There is a good isotropy of the mechanical properties obtained by the treatment according to the invention, which leads to a mechanical strength equivalent to that of the 12 h 135 C (as comparable to that of the conventional alloy 2024-T351) the direction is long and superior to that of the state very slightly under-tempered (24 H 170 C) in the cross-machine direction. There is also a good level of elastic limit and elongation at break in the short cross direction. This is superior in particular to that which is obtained by prolonged high temperature treatments (outside the invention) after 3h at 230 C. The phase J 'A13Li was present in intragranular form with a diameter less than 5 nm. The resistance to intergranular corrosion is also greatly improved compared to that of the states under revenue leading to the same level

  average mechanical characteristics.

Example 3

  Thin sheets with recrystallized and isotropic structure in alloy 2091, of composition Li 2.0%, Cu 2.0%, Mg 1.4%, Zr 0.08%, Fe + Si 0.05%, were subjected to 20-minute solution at 530 C followed by cold-water quenching, wrinkling, 2% controlled traction and conventional (monogal or monopoly) income or special income

according to the invention.

  The main income according to the invention, carried out in a ventilated air oven, was in some cases preceded by an advance made in a ventilated air oven. Cooling was done in calm air after

principal income.

  The plates were characterized in hardness or by tensile tests in the long and cross-long directions, as well as by intergranular corrosion test according to the norm AIR 9048 and corrosive corrosion test (EXCO test) with heart and surface and test of Longitudinal tensile stress corrosion cracking by immersion - alternating solution in 3.5% NaCl solution over the entire thickness of the test pieces. The impact resistance (energy absorbed) was also measured by aerospace blasting test to assess the fragility at impact of structural or fuselage parts, by looking for the energy needed to create a crack in the room at right of the deformation created by the steel ball projected onto

  sheet metal from increasing heights.

  It can be seen that the plates treated by principal income according to the invention have, with an equal yield point or hardness, a better impact strength by blasting test than the under-incurable states considered to be tolerant of damage as well as a better resistance to corrosion. intergranular and stress corrosion

  NR30 rupture at 30 days of tests carried out in the cross-long direction).

  Their resistance to flaky corrosion is, moreover, excellent on the surface of the sheets, where it is better than that of the sheets which are backed up and acceptable to the core (Table 3). All the plates according to the invention had a dense coprecipitation of phase S 'A12CuMg and phase' A13Li, the latter being of diameter less than 5

  na contrary to the classic states (sub-income, T651, overreported).

  Table 3bis shows that the income according to the invention leads, at equivalent hardness, to a better resistance to intergranular corrosion than the sub-incomes, and this with high resistance to shock (this

  which reflects the absence of fragility).

Example 4

  Spun rods of rectangular section (60x30 mm) and composition: Li 2.1% - Cu 2.6% - Mg 0.4% - Zr 0.09% - Fe + Si 0.07, were subjected after implementation solution and quenching with cold water treatments

  different durations at different temperatures in the laboratory.

  The resistance to stress corrosion was measured in the short cross-direction on rings C according to immersion-emersion test

  alternating in solution 3.5% 7. NaCl according to the AIR 9048 standard.

  Surprisingly, it appeared that the incineration treatments according to the invention at 230 ° C. in an air oven (air cooling) leading to a dense precipitation of T'1 or T1-Al2CuLi phase and a significant dissolution of the C phase. -A13Li (large, highly dispersed particles of phase <'of size greater than 30 nm and large density of very fine phase particles J': diameter less than 6 nm) leading to satisfactory levels of resistance to stress corrosion,

  unlike under-incomes or even conventional over-incomes.

Example 5

  Spun flats of 100x13 nm format and non-recrystallized structure (Li composition 1.8%, Cu 2.04%, Mg 1.52%, Zr 0.10%, Fe + Si 0.05% controlled by atomic absorption) after treatment of the solution for 2 hours at 528 ° C., conventional or inventive treatment and a main treatment according to the invention (in a salt bath oven) followed by water and controlled contraction at 2.5% of remanent deformation. The structure according to the invention was characterized by a total absence of coarse <-A13Li phase (except around A13Zr phase particles) and by an extremely fine precipitation of phase C '(size less than 4 nm) coexisting with the precipitation of phase S 'A12CuMg for the durations

  of principal income described in the invention, and T2-A16CuLi3.

  Table 5 gives the average longitudinal tensile strength characteristics obtained on specimens taken at mid-width

and at the edge of the flat.

  There is a significant improvement in the elongation at break as well as, on tensile test pieces treated according to the invention,

  a very weak tendency to laminated intergranular rupture.

Example 6

  Flats spun in 2091 of 100x13 mm section of composition A and B and identical in origin to those flats described in Examples 1 and 5 above have undergone, after quenching, possibly hardening, main income and cooling at room temperature, an income

  complementary as described in the invention.

  Table 6 shows the mechanical strength improvements thus obtained, which allow the alloys treated according to the invention to have, after complementary income at 170 or 190 C, a level of mechanical characteristics comparable to that of the T6 or T651 state, as well as better resistance to intergranular corrosion, without significant reduction in ductility and necking values. The size of the phase C'A13Li after complementary income is of the order of

20 nm.

Example 7

  T351 thin alloys (thickness 1.6 mm) in initial 2091 alloy identical to those of Example 3 were subjected to conventional single-income treatments as well as to main income treatments followed by additional income according to US Pat. 'invention. These were either carried out with return to ambient temperature (cooling air after main income), or continuously by controlled cooling inside the oven (at a rate of descent of the order of

  at 40 C / hour), by admission of fresh air.

  Table 7 gives the values of hardness, impact resistance (energy absorbed by blasting test) and resistance to intergranular corrosion. They are overall improved compared to

  treatment of light sub-income 12 h to 1700 C.

Example 8

  38.5 mm thick sheets of alloy 2091 of the same origin and composition as those of Example 2 have undergone, after quenching and controlled traction of 2%, conventional monopalaire incomes and a main income treatment of 3%. h at 230 ° C. followed, after continuous cooling at 20 ° C./h at 230 ° C. to 190 ° C., with a supplementary income of 12 hours at 190 ° C. in the same oven with a final cooling of 20 ° C./ hour of 190 ° C. 170 C and output

in a calm air until the ambient.

  Table 8 gives the results of the characterization carried out

  identical to that of Table 2 (see Example 2).

  It is noted that the income according to the invention clearly improves the elastic limit and cross-resistance properties, as well as the isotropy of the mechanical properties, while maintaining an interesting level in the longitudinal direction and improving the resistance.

to intergranular corrosion.

  The structure observed after continuous two-phase treatment according to the invention is characterized by a coarse reprecipitation of spherical Ia13Li phase (size greater than 20 nm) and also in elongated form along the many needles of phase S'-A12CuMg in

the matrix (at the interface).

T ''. Sensitivity to

  Mechanical characteristics of tensile corrosion

  Traction, granular Traction Long sens mean cross long gauze controlled Income state Long meaning Long cross seam NaCl + H202 test

  after R 0.2 Rm A E R 0.2 Rm A E mid

  quenching Surface area P (MPa) (MPa) (%) (%) P (MPa) (MPa) (%) (%) thickness -_ without (T4) 412 500 11.2 10.7 303 427 17.5 24, 5 nil low -_ 12 h 150 C 460 520 8.7 9.0 338 452 9.7 23.7 medium high (under revenue) -12 h 170 C 466 530 10 10.7 344 456 13.7 25, 2 strong strong (under income) 45 minutes 240 C 415 504 11.2 17.9 346 432 11.2 30.2 very low (according to the invention) low -_ 12h 150 +45 min Z40 C 410 502 12 17.9 345 433 12.5 33.0 very very (according to the invention) low low _ 12h 170 +45 min 240 C 404 496 12, 5 22.6 344 422 11.2 33.0 weak weak ( according to the invention) 2% without (T 351) 392 470 15 12.9 288 404 16.2 28.2 none very low 12h 150 C 486 536 7.5 14.5 354 462 11.2 28.9 very very (under income) weak strong 12h 170 C 500 554 10 7.7 357 471 10 23.3 medium high (under income) mn 240 C (according to 422 484 12.5 39.6 381 430 10.0 41.3 nil tr.faible

12h 150 C + (in-

  min 240 C (vv) 418 480 12.5 41.0 384 428 11.2 39.0 none low (y-2h 1700C + tion min 240e 426 486 12.5 41.0 382 425 11.2 43.8 nil tr.faible

TABLE 2

  State of Revenue I Mechanical Traction Characteristics (MPa) International Corrosion Test

  Longitudinal Direction Lon Direction T.L. Direction 60 / L Direction T Corrosion Sensitivity P -_.-- I ---- - --- Corrosion

  Rpo, Rm /% Rpo, Rm A /% Rpo, Rm /% Rpo Rm A /% intergranular

  2 2 2 2 .. at 12h 135 C (under income 394 472 2.5 331 443 14.9 295 415 18.2 286 421 7.0 I Forte nu B 24h 170 C (light under 443 518 0.6 383 484 8, 7 340 452 13.1 335 458 5.6 I High income) C 3h 230 C (if ifiv.) 399 455 8.5 391 7.9 36Q 416 9.1 355 425 5.0 P + I Low, 36 41 9,. 35 42,. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ E 12h 235 C (not inv.) 377 443 7.2 372 430 6.7 353 415 8.0 353 409 3.3 P + I Very low N) 0% o OJ. IDvN% ç <'uoTinlos ua aauialle uoTslaunua-uoTsaaWuTp Tessap sino OC ua (ed &) ainidni uou ap aluTelquoo. OC dN. ** aljeo sx1 = Jd aeot a uua4om = H alqTej = j alqTeg sail j (sa.UbTd) allnU atelnueuigalauT uolsoiaoD z Ilqisuaus * * OoIi 8a = aa aGllo = From aagpomu = aa alqTe = Va saqueiallTnaj saaUbTld = Ja allnu = N uviallTnaj uoTsoiioj ** a2ellTq ap 3sa * LJ "l :::::::: ::::) r ,. {0 0 <:: :::: :::: :) 0gz> O (08Z <] R * j 'aaYa za * Z'16: z1 *% 8 t 1: z0 6St * ^) o9uS + oLQl C (ZN s: see N:' T o 0: Z OLC 6 T VZ: 9L,:,) 0ZU = + oqzl (has its state: z ::: :) (08 <] N iat VU * N '6'01' O0 ZE úL '6' t 898 S (AUJ4 UoTa) DoiQzUlu) O (> ttttttt) ooz t N zt aaUR / vaJ The L T1t: 88 '11 t9Z t 998 t (") DO0fl + DOL1ZI) (oOZ S t * 9 o) (09> J t J ta' t 'It, 9t 0 IZ7' LC ' (), O: ZOql + D, O, IZZl) o] ttt ja: Z'1 * 6 ZCft 9LC. 6 * f7. LC (tAuT, uoles) OCFZ: útCq) (tt S t I ttt * tt) (X szat * tt * tt S 001 to Raa a ú'LT 998 87C.9 f (nueAea snos) DoLIqZ (001> il ilt , here SSI 6ZC: LI 9: úf 8 ZEC * (nuaaai snos) DO1qZ)

(0 0 '' ':::: ::')

  (t ':,:: tt):' li :, 'dK: (] l: /: t'8I (:): Z (eq) :( d): (6: 7) :( e) :( edR) t) ((vdw) OCXNU ineD: azans a0naos t aDe; ins v ymutz 'oduy unj Z'odX) (z' ':: ::::: t :)

((****) '' '' '')

  (NOISOXIODz (**) NI * 1'V: a: s :: V: i :: s (nuala Ino) (15uL I) TTUT 9) (': vr, a', - Snaa NOISOUXOD Raa siz :: dN NOIDVl as vD sabsIaDvxvD: a: aa tUtti 9 <1 = - 160t aB1t1e 118 88UUi S191 if neaqe

(..: mm: '::: 160: 8} l: asots1e1g TABLE 3a T8 thin alloys 2091 - e =

1.6 mm

Claims (1)

INCOME HARDNESS ENERGY SENSITIVITY TO CORR. (Initial state T 351) IMPACT VICKERS ROSION INTERGRANULAR (initial state T 351) H Hv 2 W (kg / mm) (J) Area Heart 12h 150 C (under income) 135 10, 5 TF TF 12h 170 C (under income) 140 7.3 FF 12h 190 C (T 651) 153 4.1 f F 130 h 230 C (according to the invention) 134 9.1 mM 1'invention). 3h 230 ° C. ("") 134 8.6 tf Mf l [4.30 h 230 C ("") 135 7.3 mH 6.32 C (+) 133 7.3 M Mf 46 min 240 C (according to 135 109 mM) in210 C (s eventn) 13 5 10.9 m M 12h 210 "C (over-subscribed) 142 4.5 f M TA1BLEU 4 LAST LIFE INCOME (days) 48 h 110 C sub-income 8.3.3 12 h 150 C 5.1.2 48 h 190 C (slightly under income) 3.3.3 3 h 190 C (under income) 4.1.4 12 h 190 C (T6) 1.11 48 h 190 C (on income) 5.6, NR30 3 h 230 C (according to the invention) 3NR30 * 24 h 50 C + 3 h 230 C (according to the invention 3NR30 * tion) * 3NR30: 3 test pieces not broken in 30 days of test TABLE 5 EDGE LARGET CENTER LARGET STATE - SIZE Rp0.2 Rm A% Rp0.2 Rm A (MPa) (MPa) (MPa) (MPa) T4 (matured) 364 454 8 313 421 12 Fine (> 5 nm) very fine <4rim min at 250 C 380 470 12 306 409 14 s A Cug + S 'Ai2Cu Mg Very fine <4rimi min at 230 C 414 515 12 364 465 14 very fine <4nm + SI Ai2CuMg dense min at 230 C + Traction 2 5% 482 518 9.5 442 482 9.6% Traction 2.5% 2024-T4 320 500 15 Conventional References 2024-T351 400 530 13   Traction 2% / O'OT $ -I-Oa 'W, 1'0-Z' ZST-lS '*% "o'Z-no', 8'T-1T- (8 goO-mosio 'hZTl'OZ ## EQU1 ## where: ## EQU1 ##, ## EQU1 ## where: ## EQU1 ## % (91) Do061 q ZG - 0 DoOLT q ZI eTqTeU eTT; Tliln S ZlS "9i 'L ZLS 8 5 + Do O, uTU çV Y l * Tq eTqTej -lTu q.Xj IS ILIV THE 9 9LS 'S (IS91) D0O6lqvZ V, Z <(UoT JuAUTT, UOTUS) * Tq DoOLT q Zl elqTBA --I; * "L' i'9 OIS M SO L% 6S OS + OoOz UTl sG V Ouu" oK eTqT SL Sis OIS 0u O1 809 clS (91) DoO6lqViZ V 0 enum; d2 ^ î * 3W4PU OV z'oda __V ma-ZfOd UOT; IOzaoo luo uj'.AWL 8U "S * 3UOi 0 ue * 2WiTlTe TT Y3TTIqTmuoS (Wvqi) uo lz.aptnb1uwmopnbTam; .z.wIe. nuOAa1op 3awH la3 adma3 82d e Iitig23uole uox3aouj ... @RIelzUoa UOl29 9 fW'iIV3,   IMPACT ENERGY SENSITIVE TO CORROSION HARDNESS VICKERS INTERGRANULAR INCOME W INCOME HV (K / mm2) (J) Heart Surface   (J) 3h 2300 C + 12h 1900 C 144 4.1 very weak low (ref.Air intermed.) 3h 2300 C + 12h 1900 C 142 5.5 very weak low (ref.controlled) 3h 2300 C + 3 h 1900 C 140 6.8 very weak (controlled ref) low 3h 2300 C + 3h 2100 C moderately o (ref.controlled) 138 6.4 weak ts 3h 230 C + 12h 170 C weakly controlled (controlled ref) 144 5 weak foye 3h 2300 C + 12h 210 C (ref.Air intermed.) 137 5.5 nil low (ref.Air intermed.) 3h 230 C + 48h 210 C 133 55 none zero (ref.Air intermed.) 133 5.5 null null (ref.Air intermed.) 12h 1700 C o12h170r C 140 7.3 strong strong (under income) 0s o Vl tj1 -o elqTel s8ij The I Llà SL8 Z'L IúC 7LC 1'9 6 "66u S ' L 79t 9O9 -n) aa alqTej saJl S * LúG 06C l * L IST Z6ú 9997 919 IúL G89 GZ9 ('uauT, - I uOlas) o061 qZl + oOCZ qú elloj B euuaeoN' [ú 999 Z9c 9 * 6 699 9u [O0L IOS 619 898 9 [5 ITL (I19L) oOLI q8n elqetB Bq auuaXom9 '[997 88u 8'6 '99 98u 8'L 569 0ú9 CZ úZSúL' (Ig91) o061 qZI% V i Z'odX% V t Z 'odd% V% Z' od% y M Zl 'oda NOISOaROD) 1 axvi 5lANIS Dj0 had 7 /, o0 suas 1-1 sueS Suoq sues 1aaad aaH V12 NOISOU10D V'I Y ZIII7IIISURS   (UdN) NOIIDVUI aa saniL OVDaI san0IbSIHaDVzivD 8 fValiVfV   1. A method for heat treatment of Al alloys containing Li and at least one main element taken from the group Cu, Mg, Zn and any minor elements such as Zr, Mn, Ni, Hf, Ti, Be in more unavoidable impurities such as Fe and Si, remains Al, comprising a dissolution and quenching, a possible plastic deformation, followed by at least one income, characterized in that this income is made in a range delimited by a parallelogram , in a time - temperature diagram, whose vertices have coordinates A 270 C - 3 min B 270 C 48 min C 215 C - 16 h D 215 C - 1 h. 2. Method according to claim 1, characterized in that the main income is carried out in a temperature range delimited in a temperature-log time diagram by a parallelogram whose vertices have the following coordinates: E 260 C - 5 min F 260 C - lh20 min G 220 C - 12 h H 220 C - 45 min.   3. Method according to one of claims 1 or 2, characterized in that   that the isothermal income is carried out at a temperature between To10 C and To +25 C with: To (C) = 65 + 80 (% Li) + 5 (% Mg) + 1.5 (% Zn) the percentages being in weight, the alloy containing between 1.7 and 2.6   % Li, with 0.2 <Cu <3.4% - Mg <7% and Zn \ 3%.   4. Method according to one of claims 1 to 3, characterized in that   that the quenching is followed by a plastic deformation between 0.5 and 5%.   5. Method according to claim 3, characterized in that the main income is preceded by a maturation at ambient temperature or a precursor carried out in a temperature range of less than 200 ° C. and for a maximum duration t'M such that e ( Oc) = -60 log teM (hours) + 260.   6. Method according to claim 5 characterized in that the pre-income is carried out in a temperature range from 120 to 180 C and   for a minimum duration t'm such that 0 (C) = 180-60 log t'm (hours).   7. Method according to one of claims 1 to 6 characterized in that   that the main income is followed by a complementary income made at temperature e lower than that of the main income and included between 165 and 215 C.   8. Method according to claim 7 characterized in that the duration of the additional income greater than a duration t "m correspond to the formula e (C) = 230-60 log t" m (in hours) and less than 60 h.   9. Method according to one of claims 7 or 8 characterized in that   that the temperature of the complementary income is between 170 C and 210 C.   10. Method according to one of claims 7 to 9 characterized in that   that the two main and complementary income are executed separately.   11. Method according to one of claims 7 to 9 characterized in that   that the 2 main and complementary income are separated by a continuous cooling.   12. Method according to claims 1 to 11 characterized in that   a work hardening between 0.5 to 5% between the 2 incomes main and complementary.   13. Product according to one of claims 1 to 6, characterized in that   that the matrix containing Al contains a fine dense precipitation of spherical and fine phases (A13Li) (size <10 nm), as well as a precipitation in platelets, needles or rods of phases T'1 or T1 (A12CuLi), S ' or S (A12CuMg), and / or T'2 or T2 (Al6CuLi3) and optionally c ', coarse and rare phase particles of which the size exceeds 25 nm.   14. Product according to claim 13 characterized in that the phase It has a size <5 nm.   15. Product according to one of claims 7 to 12, characterized in that   that the matrix A1 contains, besides the dense precipitation of the phases T'1 or T1, S 'or S, T'2 or T2, a precipitation of individual and spherical phases J' of size greater than 10 nm and a heterogeneous precipitation of phase J 'of elongate or semicircular shape at the interface between phases T'1 or T1, S' or S and of the matrix Al.