Al-zn-cu-mg alloys on base of aluminium, procedures for their production and implementation

FIELD: metallurgy.

SUBSTANCE: invention refers to alloys on base of aluminium, particularly to Al-Zn-Cu-Mg alloys on base of aluminium, and also to procedure of fabrication of rolled or forged deformed product of it and to rolled or forged deformed product proper. The procedure consists in following stages: a) casting an ingot, containing wt % Zn 6.6-7.0, Mg 1.68-1.8, Cu 1.7-2.0, Fe 0-0.13, Si 0-0.10, Ti 0-0.06, Zr 0.06-0.13, Cr 0-0.04, Mn 0-0.04, additives and other side elements ≤0.05 each, b) homogenising of the said ingot at 860-930°F or, preferably, at 875-905°F, c) hot deformation treatment of the said ingot with temperature at input 640-825°F, but preferably - 650-805°F by rolling or forging to a plate with finish thickness from 2 to 10 inches, d) thermal treatment for solid solution and quenching the said plate, e) drawing the said plate with residual deformation from 1 to 4 %, f) ageing the said plate by heating at 230-250°F during from 5 to 12 hours and 300-360°F during from 5 to 30 hours during equivalent time t(eq) between 31 and 56 hours. Equivalent time t(eq) is determined from formula:

where T corresponds to instant temperature in K during annealing, while Tcontr corresponds to control temperature equal to 302°F (423K), and t(eq) is expressed in hours.

EFFECT: production of deformed product possessing improved combination of mechanical strength for corresponding level of crack resistance and resistance to corrosion cracking under load.

8 cl, 2 dwg, 10 tbl, 4 ex

 

Cross-reference to related applications

This application claims the priority of provisional application U.S. serial No. 60/651197, filed February 10, 2005, the contents of which are incorporated here by reference in its entirety.

The level of technology

The technical field

The present invention relates in General to alloys based on aluminum and, more specifically, to Al-Zn-Cu-Mg alloys based on aluminium.

Description of the prior art

Al-Zn-Cu-Mg based alloys aluminium is widely used in the aerospace industry for many years. With the development of aircraft structures and efforts aimed at addressing the problem of reducing both weight and cost, designers are constantly looking for the optimal balance between properties such as strength, toughness and corrosion resistance. The improvement of the processes of casting, rolling and annealing can best way to provide additional regulation within the chart of the composition of the alloy.

Thick rolled, forged or extruded products made of Al-Zn-Cu-Mg alloys based on aluminum, is used, in particular, to obtain whole-treated high-strength structural parts for the aviation industry, for example, elements of the wings, such as wing spars, etc. that usually is about getting in the machining of thick deformed profiles.

The performance characteristics obtained for various properties, such as static mechanical strength, fracture toughness, resistance to stress corrosion cracking under stress, sensitivity to hardening, fatigue strength, the level of residual voltage will determine the overall characteristics of the product, the possibility of a structural designer to use its reasonable manner, and the ease with which it can be used in further stages of processing, such as, for example, machining.

Among the above properties, some are often contradictory in nature, and must therefore be a compromise. Contradictory properties are, for example, static mechanical strength against viscosity and strength against resistance to stress corrosion cracking under the strain.

In known from the prior art sources described Al-Zn-Cu-Mg alloys with high fracture toughness and high mechanical strength.

For example, in U.S. patent No. 5865911 described aluminum alloy consisting essentially of (in mass %) of about 5.9 to 6.7% zinc, from 1.8 to 2.4% copper, from 1.6 to 1.86 per cent of magnesium, from 0.08 to 0.15% zirconium, the remainder aluminum and incidental elements and impurities. In this patent'911, in particular, mentioned the compromise between the article the static mechanical strength and toughness.

In U.S. patent No. 6027582 described rolled, forged or extruded products of Al-Zn-Cu-Mg based alloy aluminium, of a thickness exceeding 60 mm with a composition (in mass %): Zn: 5,7-8,7, Mg: 1,7-2,5, Cu: 1.2 to about 2.2, Fe: 0,07-0,14, Zr: 0.05 to 0.15 when Cu+Mg<4,1 and Mg>Cu. In this patent'582 also described improved sensitivity to hardening.

In U.S. patent No. 6972110 proposed alloy, which preferably contains (in mass %): Zn: 7-9,5, Mg: 1,3-1,68 and Cu: 1,3-1,9, it is proposed to maintain Mg≤(Cu+0,3). This patent'110 discloses the use of three-stage processing ageing with the aim of improving the resistance to stress corrosion cracking under tension. Three-stage aging is long and difficult to master, and it would therefore be desirable to achieve high corrosion resistance without the mandatory implementation of such thermal processing.

The invention

The objective of the invention was to provide an Al-Zn-Cu-Mg alloy having a special range of composition, which provides for deformed products improved compromise between mechanical strength for the appropriate level of fracture toughness and resistance to stress corrosion cracking under the strain.

Another object of the invention consisted in the method of manufacturing a deformed aluminum products (products), which provides in ocseny compromise between mechanical strength for the appropriate level of fracture toughness and resistance to stress corrosion cracking under the strain.

To address these and other objectives of the present invention is directed to rolled or forged deformed product from an alloy based on aluminum, having a thickness of from 2 to 10 inches and containing or mainly consisting essentially of (in mass %):

Zn 6,2-7,2

Mg 1,5-2,4

Cu: 1,7-2,1

Fe: 0-0,13

Si 0-0,10

Ti 0-0,06

Zr 0,06-0,13

Cr 0-0,04

Mn 0-0,04

impurities and other undesired elements ≤0,05 each.

After the molded product is subjected to heat treatment for solid solution hardening and ageing, and in a preferred variant embodiment has the following properties:

(a) the minimum service life without failure after corrosion cracking under tension at least 50 days, and preferably at least 70 days, when the voltage level in the direction of the ST 40 ksi (kilopond psi);

b) conventional yield stress tensile, as measured in the direction L at a quarter thickness, over 70-0,32t ksi (t means the thickness of the product in inches), preferably more than 71-0,32t ksi, and more preferably more than 72-0,32t ksi;

C) impact strength in the direction L-T, measured on a quarter of the thickness, over 42-1,7t ksi√inch (t means the thickness of the product in inches).

The present invention is also directed to a method of manufacturing a rolled or forged deformed product from an alloy based on aluminum, including with the BOJ following stages:

a) casting an ingot containing or mainly consisting essentially of (in mass %):

Zn 6,2-7,2

Mg 1,5-2,4

Cu: 1,7-2,1

Fe: 0-0,13

Si 0-0,10

Ti 0-0,06

Zr 0,06-0,13

Cr 0-0,04

Mn 0-0,04

impurities and other undesired elements ≤0.05 for each;

b) homogenizing the ingot at 860-930°F or, preferably, when 875-905°F;

c) hot deformation processing of the ingot to slab with finite thickness from 2 to 10 inches with a temperature at the entrance 640-825°F, and preferably 650-805°F;

d) heat treatment for solid solution hardening plate;

e) stretching of plates with residual deformation from 1 to 4%;

f) aging the plate by heating at 230 to 250°F for 5 to 12 hours and 300-350°F for 5 to 30 hours, during the equivalent time t(eq) between 31 and 56 hours, and preferably between 33 and 44 hours.

The equivalent time t(eq) is determined by the formula:

where T represents the instantaneous temperature in K. during annealing, and Tcounterrepresents a control temperature, chosen to 302°F (423 K), and where t(eq) is expressed in hours.

Brief description of drawings

Figure 1: graphs TYS(L) - K1C(L-T) for plate And according to the invention (8 inch) against 7040 (comparative plate In thickness 8.27 in) and 7050 (comparative plates D and E the thickness of 8 inches).

Figure 2: graphs TYS(L) - Karr(L-T) on the I plate And according to the invention (8 inch) against 7050 (comparative plates F and G thick 8.5 inch).

The accompanying drawings, which are included in the description and are part of it, illustrate preferred in the present variant embodiment of the invention and, together with the above General description and the following detailed description of a preferred variant embodiment, serve to explain the principles of the present invention.

A detailed description of the preferred variant of the incarnation

Unless specified otherwise, all instructions relating to the chemical composition of the alloy, expressed as percentage by weight calculated on the total weight of the alloy. Denote alloys provided in accordance with the instructions of the Aluminum Association, well-known specialists in this field of technology. Defining the conditions described in ASTM E716, E1251.

Unless otherwise stated, the static mechanical characteristics, i.e. ultimate tensile strength UTS, yield strength in tension TYS and elongation at break E determined in the tensile test according to standard ASTM V, and the place where they select samples, and their direction is determined according to the standard AMS 2355.

Fracture toughness K1Cdetermined according to ASTM E. A graph of the intensity of the voltage against the spread of cracks, known as the curve R, determined according to ASTM E. To eticheski intensity factor voltage K Within other words, the intensity factor, which makes the crack is unstable, calculated on the basis of curve R. the intensity Factor voltage KWithalso calculate, exposing the initial crack length to the impact of the critical load at the beginning of the monotonic load. These two values are calculated for the test sample of the required form. Karrdenotes the KCOcorresponding to the test sample, which was used to carry out tests on the curve R.

It should be noted that the width of the test panel used in the test for impact strength, can have a significant impact on measured in this test, the stress intensity. Used samples of CT. In the absence of other indications, the width W was 5 inches (127 mm) when V=0.3 inches, and the initial crack length ao=1.8 inch.

Tests on SCC was carried out according to the standard ASTM G47 and G49 towards ST for samples at half the thickness of T/2.

The term "structural element" is a term well known in the art and related parts used in mechanical design, for which the static and/or dynamic mechanical characteristics are particularly important relative to the performance of a design and for what toroi is usually required and is calculated design. They are usually the details, the destruction of which can carry serious threat to the security of the mechanical design, its users or third parties. In the case of aircraft structural elements include the elements of the fuselage (such as the fuselage skin, stringers, frames, b frames, the details of the wings (such as a wing skin, stringers or stiffeners, ribs, spars), tail (such as horizontal and vertical stabilizers), joists, guides, seats, and doors.

Aluminum-zinc-magnesium-copper deformed product according to one preferential variant embodiment of the invention has the following composition (limits included):

Table 1
The ranges of the compositions of the alloys according to the invention (wt.%, the rest - Al) in one embodiment of the incarnation
ZnMgCu
Wide6,2-7,21,5-2,41,7-2,1
Preferred6,6-7,01,5-1,8 1,7-2,1
More preferred6,7-7,01,68-1,81,7-2,0
Even more preferred6,72-6,981,68-1,81,75-2,0

In another variant embodiment of the invention, the ranges of composition of the alloy according to the invention are as follows:

Zn: 6,6-7,0, Mg: 1,68-2,4, Cu: 1.3 To 2.3.

The minimum content of dissolved substances (Zn, Mg and Cu) is often important or necessary to obtain a desired strength. The content of Zn+Cu+Mg is preferably more than 10 wt.%, and preferably more than 10.3 wt.%. For the same reason, the Zn content should preferably be at least about 6.2 wt.%, and preferably at least 6.6 wt.%, of 6.7 wt.% or even 6,72 wt.%, in General exceeds the content of Zn in the alloy 7040 7050 or. Similarly, the content of Cu+Mg is preferably more than 3.3 wt.%, and preferably more than 3.5 wt.%.

On the other hand, in some embodiments it may be desirable to limit the amount of zinc to obtain a high corrosion resistance without using time-consuming 3-stage aging treatment. For this reason, the content of Zn should mainly stay below about 2 wt.%, and preferably lower than 7.0 wt.% or even 6,98 wt.%, somewhat lower than the content of Zn in the alloy 7085.

The high content of Mg and Cu may affect the characteristics of the fracture toughness. The total content of Mg and Cu should preferably be maintained below about 4.0 wt.%, and preferably below about 3.8 wt.%.

Alloy, suitable for the present invention preferably further comprises zirconium, which is typically used to control the grain size. The Zr content should preferably be at least about 0.06 wt.%, and preferably about 0.08 wt.%, to influence the recrystallization step, but it should preferably be below about 0.13 wt.%, and preferably below to 0.12 wt.% with the aim to minimize sensitivity to hardening and troubleshoot problems during casting.

If desired, during casting can usually be added titanium associated with boron or carbon, to limit the size of the grains in the state after casting. According to the present invention, the content of Ti is typically up to about 0.06 wt.% or approximately 0.05 wt.%. In a preferred variant embodiment of the invention, the content of Ti is from about 0.02 wt.% to about 0.06 wt.%, and preferably from about 0.03 wt.% up to approximately 0.05 wt.%.

The proposed alloy may further is about to contain other elements at a lower level, in some embodiments, an embodiment is less preferred basis. Iron and silicon are typically affect the characteristics of the fracture toughness. Typically, the content of iron and silicon should be kept low, for example, preferably not to exceed about 0.13 wt.% or preferably about 0.10 wt.% for iron, and not to exceed about 0.10 wt.% or preferably about 0.08 wt.% for silicon. In one variant embodiment of the present invention, the content of iron and silicon is ≤0.07 wt.%. The presence of chromium should preferably be avoided, and usually it should be maintained below about 0,04 wt.%, and preferably below about 0.03 wt.%. The presence of manganese is also preferably should be avoided, and usually it should be maintained below about 0,04 wt.%, and preferably below about 0.03 wt.%. In one variant embodiment of the present invention the alloy is essentially free of chromium and manganese (this means that Mn or Cr is not specifically add, and, in the presence of these elements, they are present in quantities not exceeding the level of impurities, which may be less than or equal to 0.01 wt.%). Elements such as Mn and Cr, can increase sensitivity to hardening, so their contents in some cases, it may preferably be maintained less than or equal to when is Erno 0.01 wt.%.

A suitable method of obtaining strain products according to the present invention includes: (i) casting an ingot or billet of the alloy according to this invention; (ii) carrying out homogenization at a temperature of from about 860 to about 930°F or, preferably, from about 875 to about 905°F; (iii) conduct hot transformation in one or more stages by rolling or forging, with temperature input, component of from about 640 to about 825°F, and preferably between about 650 and about 805°F, prior to the end plate thickness from 2 to 10 inches; (iv) conducting a heat treatment on the solid solution at a temperature of from about 850 to about 920°F, and preferably between about 890 and about 900°F for 5 to 30 hours; (v) carrying out quenching, preferably with water at room temperature; (vi) carrying out stress relieving by controlled stretching or compression residual strain, preferably less than 5%, and preferably from 1 to 4%; and (vii) the process of aging.

In one variant embodiment of the present invention, the initial temperature of the hot transformation is preferably from 640 to 700°F. the Present invention finds particular applicability for thick products of a thickness of more than about 3 inches. In a preferred variant of embodiment d is formed product of the present invention is a plate of thickness from 4 to 9 inches or mainly, from 6 to 9 inches, containing alloy according to the present invention. Primarily, the present invention uses "perestaranie status" (type T7) to improve the corrosion properties. Conditions that can be appropriately used for the products according to the invention, include, for example, T6, T, T, kzt76, T, T, T, T or T, thus are preferred status T and T. The aging treatment is mainly carried out in two stages, the first stage at a temperature of between 230 and 250°F for 5 to 20 hours, and preferably for 5 to 12 hours, and the second stage at a temperature comprising between 300 and 360°F, and preferably between 310 and 330°F for 5 to 30 hours.

In an advantageous variant embodiment is equivalent to the ageing time t(eq) is between 31 and 56 hours, and preferably between 33 and 44 hours.

The equivalent time t(eq) at 302°F is determined by the formula:

where T represents the instantaneous temperature in K. during annealing, and Tcounterrepresents a control temperature, chosen to 302°F (423 K). t(eq) is expressed in hours.

A narrow range of composition of the alloy according to the invention is chosen principally for the purpose of compromise strength against viscosity, gave deformirovny the major products unexpectedly high corrosion resistance.

Deformed products according to the present invention is mainly used as structural elements or build in structural elements for construction air flying machine.

In an advantageous variant embodiment, the products according to the invention is used in the spars of the wings.

Mentioned, as well as other aspects of the present invention are explained below in more detail with reference to the following illustrative and non-limiting examples.

EXAMPLES

Example 1

He cast seven bars: one of the product according to the invention (A), 2 - standard alloy 7040 (b, C) and four of the standard alloy 7050 (D, E, F and G), with the following composition (table 2):

Table 2
Composition (wt.%) casting according to this invention and comparative castings
SiFeCuMnMgCrZnTiZr
And (Invention)0,07 0,081,970,00351,680,00056,80,040,11
B (Comparison)“7040”0,040,05of 1.570,00431,970,03236,40,0370,11
C (Comparison)“7040”0,040,071,520,00011,900,00056,30,030,11
D (Comparison)“7050”0,040,072,300,00652,040,014456,30,0340,08
E (Comparison)“7050”0,050,072,250,00822,010,00656,2to 0.0320,09
F (Comparison)“7050”0,050,072,220,00212,080,00426,20,0330,09
G (Comparison)“7050”0,030,062,090,00012,020,00056,40,0300,08

Then the ingots were peeled and homogenized at a temperature of from 870 to 910°F. the Ingots were subjected to hot rolling to a plate of finite thickness between 8.0 inches (203 mm) and 8.5 inches (208 mm) (plate a and b-G). The inlet temperature in the hot rolling mill amounted to 802°F (plate A). For comparative PL is t inlet temperature in the hot rolling mill was between 770 and 815°F. The plate was subjected to heat treatment in solid solution at a temperature keeping 890-900°F for 10 to 13 hours. Plates were tempered and stretched with a residual elongation of 1.87% (plate a) and in the interval between 1.5 and 2.5% for the comparative plates. The time interval between quenching and stretching is of great importance for the regulation of the level of residual voltage, according to this invention, this period of time is preferably less than 2 hours and even more preferably less than 1 hour. For plates And a time interval between quenching and stretching was 39 minutes.

Plate And subjected to two-stage aging: 6 hours at 240°F and 24 hours at 310°F and comparative plates were subjected to a standard two-stage aging.

As a result of this thermomechanical processing received state T. All tested samples were essentially neperekreshchennymi, with the volume fraction of recrystallized grains is less than 35%.

The samples were subjected to mechanical tests to determine their static mechanical properties and their resistance to crack propagation. Yield strength tensile, tensile strength and elongation at break are shown in table 3.

td align="justify"> 8,27
Table 3
Static is mehanicheskij properties sample
SampleThicknessDirection LDirection LTDirection ST
UTS
(ksi)
TYS
(ksi)
E
(%)
UTS
(ksi)
TYS
(ksi)
E
(%)
UTS
(ksi)
TYS
(ksi)
E
(%)
A8,074,569,99,375,167,74,271,963,24,0
B8,2772,367,310,872,7to 66.36,969,262,26,4
C72,867,210,274,265,66,270,160,8the 5.7
D8,072,263,69,071,861,37,269,558,8the 5.7
E8,072,663,79,072,061,3the 5.769,458,2the 4.7
F8,571,162,19,070,660,26,267,7of 57.5the 4.7
G 8,571,162,19,072,160,67,069,057,15,5

The sample according to the invention has higher strength than all the comparative examples. Compared with slabs of 7050 improved yield strength at elongation in the L direction is more than 10%. Compared with slabs of 7040 improvement is almost 4%.

Test results of fracture toughness are presented in table 4.

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Table 4
Properties of fracture toughness samples
SampleThicknessK1CKarr
L-T
(ksi√inch)
T-L
(ksi√inch)
S-L
(ksi√inch)
L-T
(ksi√inch)
T-L
(ksi√inch)
A8,028,5a 21.5 24,158,834,5
B8,2731,625,527,5
C8,2733,224,524,3
D8,027,022,824,9
E8,028,122,523,8
F8,5to 25.352,234,4
G8,527,155,237,4

Figure 1 presents a cross-graph of fracture toughness under plane deformation in the plane L-T (K1Cagainst longitudinal yield strength tensile TYS (L), while two samples were taken at the location of the plane of the quarter of the plate thickness (T/4). The sample according to the invention showed higher strength and comparable fracture toughness than samples b and C (7040), and higher strength and higher fracture toughness than samples D and E (7050). (See 1, containing details on the achieved specific values higher strength and higher fracture toughness).

Figure 2 presents a cross-graph of fracture toughness in the L-T (Karragainst longitudinal yield strength tensile TYS (L), while two samples were taken at the location of the plane of the quarter of the plate thickness (T/4). The sample according to the invention showed higher strength and higher fracture toughness than the samples F and G (7050). (See figure 2, containing the details concerning the reached values higher strength and higher fracture toughness).

Corrosion resistance under tension plates of alloy And (according to the invention) in the width direction was measured in accordance with ASTM G49. Explosive samples ST subjected to testing when the voltage of the gap 25, 36 and 40 ki. Within 50 days of exposure, none of the samples are not destroyed. This feature is much greater than the guaranteed minimum comparative products 7050 and 7040, which is in accordance with ASTM G47, 20 days exposure under stress of 35 ksi. Alloy a according to the invention showed outstanding corrosion properties compared with the known from the prior art alloys. Particularly impressive and unexpected was the fact that the plate according to the present invention showed higher level of resistance to stress corrosion cracking under tension simultaneously with a higher tensile strength and comparable fracture toughness in comparison with samples of known alloys.

Example 2

On hardened and stretched plate And according to the invention from example 1 were tested three different processing aging. Plates were subjected to two-stage aging, with the first stage between 230 and 250°F, and the second stage is between 300 and 350°F, and this two-stage processing is characterized by the equivalent time t(eq) between 20 and 37 hours, as expressed by the following equation:

where T (in degrees Kelvin) is the temperature of heat treatment, which lasts for time t (in hours), and Tcountermeans controlling the temperature, in this case, the ass is nnow level 423 or To 302°F.

Static mechanical properties and viscosity K1Cpresented in table 5.

td align="justify"> 29
Table 5
The mechanical properties of the sample aged at different conditions
LLTSTK1C(ksi√inch)
t(eq)UTS
(ksi)
LYS
(ksi)
E
(%)
UTS
(ksi)
LYS
(ksi)
E
(%)
UTS
(ksi)
LYS
(ksi)
E
(%)
L-TT-LS-L
2276,673,28,077,370,92,873,565,34,528,0a 21.524,0
75,471,28,776,268,74,572,664,24,228,321,624,4
3674,569,99,375,167,74,271,963,24,028,5a 21.524,1

The slope of the strength changes with increasing equivalent time was surprisingly and unexpectedly low, the falling strength of only about 2 ksi with increasing equivalent time from 22 to 36 hours. On the other hand, properties, stress corrosion dramatically improved with the equivalent time of 36 hours. Thus, none of the samples are not destroyed during the 50 days of exposure under this condition of aging in the case of the voltage level of 40 ksi, while none of the samples did not survive more than 20 days at a similar voltage level when you learn the other two comparative conditions of aging.

Example 3

In this example, the plate 7040 were subjected to aging to strength, similar strength, obtained for the plate As in example 1, in order to compare the corrosion characteristics.

The composition of the ingot shown in table 6.

The ingot was turned into a plate of thickness 7,28 inches with conditions in the same range as the ingots 7040 described in example 1. The plate was subjected to final aging to obtain a strength, as it is possible more close to the strength of the plate As described in example 1. The mechanical properties of the plate H are presented in table 7.

Table 7
The mechanical properties of the plate H (measured at T/4)
SampleThicknessL DirectionLT DirectionK1CL-T
(ksi√inch)
K1CL-T
(ksi√inch)
UTS
(ksi)
TYS
(ksi)
E
(%)
UTS
(ksi)
TYS
(ksi)
E (%)
H7,2875,572,212,578,271,3530,224,3

Resistance to stress corrosion cracking under tension plate N experienced in the direction of the width according to the standard ASTM G49. Explosive samples ST subjected to testing at a voltage gap of 36 ksi. Within 40 days of exposure has not collapsed, only one sample out of three. This result further emphasizes the outstanding characteristics of the plate As in example 1, in which case none of the samples are not destroyed during the 50 days under the influence of a larger voltage gap (40 ksi).

Example 4

Poured three ingot: one of the alloy according to the invention (J) and two of the comparative alloys (K and L) with the following compositions (table 8):

Table 8
Composition (wt.%) castings
SiFeCuMnMgCrZnTi Zr
J (invention)0,050,061,720,00011,750,00056,60,040,11
K (comparison)0,030,071,530,00011,730,00056,30,040,11
L (comparison)0,050,092,240,00012,110,00056,20,030,09

Then the ingots were peeled and homogenized to 870-910°F. the Ingot according to the invention were subjected to hot rolling to a plate of finite thickness of 6.66 " (169 mm), and comparative ingots were subjected to hot rolling to plate thickness of 6.5 inches (165 mm). The inlet temperature in the hot rolling mill was 808°F for plates For J. comparative plates pace is the atur at the entrance to the hot rolling mill was between 770 and 815°F. The plate was subjected to heat treatment in solid solution at a temperature keeping 890-900°F for 10 to 13 hours. Plates were tempered and stretched, at a residual elongation of 2.25% (plate J) and in the interval between 1.5 and 2.5% for the comparative plates. The time interval between quenching and stretching was 64 minutes for plates J.

Plate J was subjected to two-stage aging: 6 hours at 240-260°F and 12 hours at 315-335°F, and for comparative plates used by a standard two-stage aging, known in this technical field.

As a result of this thermomechanical processing received state T.

The samples were subjected to mechanical tests to determine their static mechanical properties and their resistance to crack propagation. Yield strength tensile, tensile strength and elongation at break are presented in table 9.

Table 9
Static mechanical properties of specimens
SampleThicknessL DirectionLT DirectionST Direction
UTS
(ksi)
TYS
(ksi)
E
(%)
UTS
(ksi)
TYS
(ksi)
E
(%)
UTS
(ksi)
TYS
(ksi)
E (%)
J6,670,663,713,871,562,48,568,358,76,8
K6,573,368,214,576,268,68,571,562,36
L6,572,263,710,572,960,9870,159,15,5

The test results fracture toughness made the Lena in table 10.

Table 10
Properties of fracture toughness samples
SampleThicknessK1CKapp
S-L
(Ksi√in)
L-T
(Ksi√in)
T-L
(Ksi√in)
J6,635,385,756,1
K6,531,984,747,4
L6,525,557,837,3

Plate J according to the invention showed very high fracture toughness, especially in S-L and T-L directions. Improving K1Cin the S-L direction was more than 10% compared with the sample J and almost 40% compared with the sample L.

Additional advantages, characteristics and modifications will be obvious to a person skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and illustrative devices presented and described here. Respectively, may be made of various modifications without violating the essence or scope of the General inventive concept defined by the appended claims and its equivalents.

All the above mentioned documents deliberately incorporated here by reference in their entirety.

In this description and in the following claims definite and indefinite articles can mean singular or plural.

In the present description and in the following claims, if given any numerical value, it is considered relevant to this exact value, and values close to this value, which would be a negligible deviation from the specified value.

1. A method of manufacturing a rolled or forged deformed product from an alloy based on aluminum, comprising the following stages:
a) casting an ingot containing, wt.%:
Zn 6,6-7,0
Mg 1,68-1,8
Cu 1,7-2,0
Fe 0-0,13
Si 0-0,10
Ti 0-0,06
Zr 0,06-0,13
Cr 0-0,04
Mn 0-0,04
impurities and other undesired elements ≤0.05 for each;
b) homogenization of the above-mentioned ingot at 860-930°F or, preferably, when 875-905°F;
c) hot deformation processing temperature at the inlet 640-825°F, and preferably 650-805°F, the above-mentioned ingot by rolling or forging what about the plate with finite thickness from 2 to 10 inches;
d) heat treatment in solid solution and hardening the above-mentioned plate;
e) stretching the said plates with residual deformation from 1 to 4%;
f) aging the said plate by heating at 230 to 250°F for 5 to 12 hours and 300-360°F for 5 to 30 h, during the equivalent time t(eq) between 31 and 56 hours, at the equivalent time t(eq) is determined by the formula:

where T represents the instantaneous temperature in K. during annealing, and Tcounterrepresents a reference temperature equal to 302°F (423K), and t(eq) is expressed in hours.

2. The method according to claim 1, in which the equivalent time t(eq) is 33 to 44 am

3. The method according to claim 1 or 2, wherein a time interval between quenching and stretching is not more than 2 hours

4. The method according to claim 1 or 2, in which the ingot contains Fe≤0,07 and Si≤0,07.

5. Rolled or forged deformed product of Al-Zn-Cu-Mg alloy based on aluminum, having a thickness of from 2 to 10 inches, obtained by the method according to any one of claims 1 to 4.

6. The product according to claim 5, whereby the mentioned product is in a state T.

7. The product according to claim 5 or 6, and the said product has at least one of the following properties:
(a) the minimum service life without failure after corrosion stress cracking (SCC) at least 50 days when the voltage level in the direction of the width (ST) 40 ksi;
b) the service is wny yield strength tensile measured in the direction L at a quarter thickness, at least 70-0,32t ksi (t means the thickness of the product in inches);
c) impact strength in the direction L-T, measured on a quarter of the thickness of at least 42-1,7t ksi√inch (t means the thickness of the product in inches).

8. The product according to claim 7, having a yield strength in tension, measured in the direction L at a quarter thickness, at least 71-0,32t ksi (t means the thickness of the product in inches).



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: product consists of following components, wt %: Zn 9.0-14.0, Mg 1.0-5.0, Cu 0.03-0.25, Fe <0.30, Si <0.25, Zr from 0.04 to less, than 0.3 and one or more elements chosen from group consisting of: Ti <0.30, Hf <0.30, Mn <0.80, Cr <0.40, V <0.40 and Sc <0.70, random elements and impurities, each <0.05, totally <0.15, and aluminium - the rest. The procedure for fabrication of product out of aluminium alloy consists in casting an ingot, in homogenisation and/or in preliminary heating the ingot upon casting, in hot treatment of the ingot into preliminary finished product with one or more methods, chosen from the group including rolling, extrusion and forging. Not necessarily, the preliminary treated product can be heated or hot treated and/or cold treated to a required shape of a blank; further formed blank is subjected to heat treatment to solid solution, to hardening blank heat treated to solid solution; not necessarily, hardened blank can be stretched or compressed, or cold treated by other way to stress relief, for example, by levelling sheet products or artificial ageing, till obtaining a required condition.

EFFECT: product with reduced tendency to forming hot cracks and with improved characteristics of strength, fracture toughness and hardness over 180 HB at artificially aged state.

32 cl, 6 tbl, 6 ex

FIELD: metallurgy.

SUBSTANCE: method involves ingot casting with the following composition, wt %: Zn 6.0 - 11.0, Cu 1.4 - 2.2, Mg 1.4 - 2.4, Zr 0.05 - 0.15, Ti <0.05, Hf and/or V <0.25, optionally Sc and/or Ce 0.05 - 0.25%, optionally Mn 0.05 0.12%, and inevitable impurities and aluminium is the rest, homogenisation and/or pre-heating of ingot after casting, hot deformation processing of ingot so that pre-processed product is obtained, heating of pre-processed product and either hot rolling of heated product to final thickness, or hot rolling and cold rolling of heated product to final thickness, heat treatment for solid solution and hardening of heat-treated product for solid solution, optional tension or compression of hardened product and optional ageing of hardened and optionally tensed or compressed product to the desired state; at that, rolled product at its final state has in fact fully non-recrystallised microstructure at least in position T/10.

EFFECT: product has increased yield point at compression and high specific energy of crack propagation, and improved viscosity and corrosion resistance properties.

21 cl, 6 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy and machine building, particularly to procedure of production of items out of high-strength, especially, super-strong aluminium alloys of system Al-Zn-Mg-Cu-Zr used for skin of wing and other power elements of gliders, aircrafts and also for land-based vehicles. The procedure consists in ingot hot rolling, in producing a work-piece, in tempering, in stretch flattening, in preliminary ageing and deformation ageing combined with shaping under a creeping mode. Preliminary ageing is carried out in two stages. At the first stage the work-piece is heated at temperature 95-115°C and conditioned during 3-10 h, at the second stage the work-piece is heated at temperature 120-140°C and conditioned during 2-5 h. Deformation ageing combined with shaping under the creeping mode is performed at temperature 145-165°C and conditioned during 5-10 h at rate of shaping not over 0.5 %/h.

EFFECT: facilitating stable high strength properties of aluminium alloys at sufficient level of corrosion resistance, fracture strength and fatigue strength, which upgrade weight efficiency and resource of item.

2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention relates to nonferrous metallurgy field, particularly to thermal treatment of half-finished products and details made of aluminium alloys Al-Zn-Mg-Cu-Zr, used in the capacity of constructional material for force-summing element in aerospace industry, and also in transportation equipment. It is implemented hardening and artificial three-stage aging, at which at the first stage it is implemented low-temperature heating at temperature 110-125°C with isolation during 1-12 hours, at the second stage - short-term heating with increased temperature 150-168°C with following regulated accelerated cooling up to the temperature 30-40°C at a rate no at least 0.5°C/min, at the third stage it is implemented low-temperature heating at temperature 70-90°C, providing emission of additional fine strengthening phases from supersaturated solid solution.

EFFECT: receiving of products, allowing high strength properties and increased fatigue resistance at high level of corrosion resistance, that provides increasing of weight efficiency and products' useful life.

4 cl, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: presented invention relates to product made of deform high-strength alloy Al-Zn and also manufacturing method of product made of this alloy. Product is implemented for steel containing following ratio of components, wt %: zinc 7.6-9.5, copper 1.3-2.4, magnesium 1.5-2.6, manganese 0.06-0.12, zirconium < 0.20, chrome < 0.10, iron < 0.25, silicon < 0.25, titanium < 0.10, hafnium and/or vanadium < 0.25 and it is not necessary cerium and/or scandium < 0.20, inevitable admixtures - less than 0.05 of each and less than 0.25 in total, the rest - aluminium, with 0.1[Cu]+1.3<[Mg]<0.2[Cu]+2.15. Method of product manufacturing includes ingot casting with above mentioned content, pre-heating of ingot after casting, ingot hot working by pressure and not obligatory fabrication till pressure workpiece, thermal processing to solid solution and hardening of heat-treated to solid solution of product. IT is received product allowing high tensile and improved combination of viscosity and corrosion behavior.

EFFECT: receiving of product allowing high tensile and improved combination of viscosity and corrosion behavior.

27 cl, 11 tbl, 4 ex

Alloy al-zn-mg-cu // 2353693

FIELD: metallurgy.

SUBSTANCE: current invention relates to product made of aluminium alloy containing wt %: zinc 6.5-9.5, magnesium 1.92-2.1%, copper 1.0-1.8, iron < 0.14, silicon < 0.20, preferentially < 0.12, zirconium 0.04-0.3, it is not necessary, one or more from: scandium < 0.7, chrome < 0.4, hafnium < 0.3, manganese < 0.8, titanium < 0.4, vanadium < 0.4 and unintentional impurity < 0.05 each and < 0.15 all together, and the rest is aluminium. Product is manufactured by method including ingot casting, its preheating, hot processing by pressure till receiving of preformed blank by one or more methods, chosen from the group containing of deform, punching and hammering, not necessary reheating of predeformed blank, hot treatment by pressure till the receiving of mould blank of necessary form, thermal treatment to solid solution of mentioned mould blank at temperature and during the time, enough for transfer into solid solution to the point all soluble components in alloy, hardening of heat-treat to solid solution blanks by means of hardening by spray cooling or hardening by water immersion or different hardening compound, optional tension or pressing of hardened workpiece, artificial aging of hardened and optional stretch or compressed workpiece till achieving of desirable condition. IT is received product allowing high tensile and improved combination of viscosity and corrosion behavior.

EFFECT: receiving of product allowing high tensile and improved combination of viscosity and corrosion behavior.

50 cl, 4 dwg, 15 tbl, 8 ex

FIELD: metallurgy.

SUBSTANCE: invention relates to thick-walled plate made of aluminium alloy with high tensile and low sensitivity to quenching and also method of production such thick-walled plates and can be used in motor industry. Plate made of aluminium alloy is received by means of continuous casting of alloy with receiving of blank of thickness more than 300 mm, blank heating till the temperature 470-490°C, blank homogenising annealing at that temperature, hot rolling of homogenised blank with receiving of plate of thickness less than 300 mm or cooling down till the intermediate temperature, which is 400-410°C, aftercooling from intermediate temperature 400-410°C till the temperature less than 100°C, plate cooling till the room temperature and plate artificial aging. Alluminum alloy allows following content, wt %: Zn from 4.6 till 5.2, Mg from 2.6 till 3.0, Cu from 0.1 till 0.2, Zr from 0.05 till 0.2, Mn maximum is 0.05, Cr maximum is 0.05, Fe maximum is 0.05, Si maximum is 0.15, Ti maximum is 0.10, aluminium is the rest and admixtures conditioned by technological process characteristics.

EFFECT: receiving of thick-walled plate, allowing high tensile throughout, with low sensitivity to quenching.

34 cl, 5 dwg, 1 ex

FIELD: metallurgy.

SUBSTANCE: product out of aluminum alloy consisting out of the following elements, mas.%: zinc 6-10, magnesium 1.2-1.9, copper 1.2-2.2; at that one or several elements are chosen out of a group, consisting of zirconium up to 0.4, scandium up to 0.4 and hafnium up to 0.3, at that aluminium and tramp additives- the rest. The said alloy optionally contains titanium up to 0.06, calcium up to 0.03, strontium up to 0.03, beryllium up to 0.002. The product with a large cross section is treated for transforming it into a hard solutuion, then tempered and artificially aged. The product with a small cross section is slowly tempered. There are suggested the following parts fabricated out of the said alloy: an aircraft wing, a structural component and a method of its fabrication, a compartment component of an airlock caisson, a profiled plate, an aircraft wing of a high carrying capacity and an aircraft of a high lading capacity.

EFFECT: products developed for higher characteristics of hardness and improved characteristics of wear and fracture resistance.

119 cl, 14 dwg, 14 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: said utility invention relates to Al-Zn-Mg alloys, namely, to alloys for welded structures, such as structures used in marine construction, during manufacture of car and industrial vehicle bodies, and stationary or movable tanks. The method involves manufacture of a plate using semi-continuous casting. The plate is made of an alloy containing, % weight: Mg 0.5-2.0, Mn < 1.0, Zn 3.0-9.0, Si < 0.50, Fe < 0.50, Cu < 0.50, Ti < 0.15, Zr < 0.20, Cr < 0.50, aluminium with its inevitable impurities being the remaining, Zn/Mg > 1.7. After that, the plate is subjected to homogenisation and/or reheating at a temperature T1 selected so that 500°C ≤T1≤(Ts-20°C) where Ts is the alloy burning temperature. The first hot rolling stage includes one or several rolling passes on a hot-rolling mill, the input temperature T2 is selected so that (T1-60°C)≤T2≤ (T1-5°C), and the rolling process is performed in such a way that the output final temperature T3 would be so that (T1-150°C)≤T3≤(T1-30°C) and T3 < T2. The strip produced at the said first hot rolling stage is rapidly cooled to the temperature T4. The second stage of hot rolling of the said strip is performed at the input temperature T5 selected so that T5≤T4 and 200°C≤T5≤300°C. The rolling process is performed in such a way that the coiling temperature T6 would be so that (T5-150°C)≤T6≤(T5-20°C).

EFFECT: enhancement of balance between mechanical properties and corrosion resistance of base metal and welded joint using simplest and most reliable method.

34 cl, 8 dwg, 20 tbl, 10 ex

FIELD: methods of reinforcing treatment of aluminum alloys.

SUBSTANCE: the invention is pertaining to the methods of reinforcing treatment of aluminum alloys, in particular, to the methods of is strain-thermal treatment. The offered method provides for processes of a hot straining and aging of an aluminum alloy of Al-Zn-Mg system containing the following alloying additives: manganese, titanium, chrome, zirconium introduced either separately or in a complex in any combinations. At that after a thermal straining conduct either a straining at the temperature of 20-200°C with an extent of 25-50 % and a recrystallization annealing - at the temperature of 500-550°C within 4-8 hours with the following quenching, or a straining at the temperature of 480-520°C with a preliminary seasoning at this temperature for 30-90 minutes with an extent of straining of 20-50 % and the following chilling in water. Before the thermal straining they conduct homogenization. The thermal straining is realized at the temperature of 400-450 °C, and the seasoning process is conducted in one - or two stages. The technical result of the invention is development of a method of the combined strain-thermal treatment ensuring improvement of the plastic performances and resistance to destruction of mainly high-strength aluminum alloys at preservation of the level of their mechanical properties.

EFFECT: the invention presents a developed method of the combined strain-thermal treatment ensuring improvement of the plastic performances and resistance to destruction of mainly high-strength aluminum alloys at preservation of the level of their mechanical properties.

FIELD: metallurgy.

SUBSTANCE: alloy on base of aluminium contains following components wt %: zinc 5-8, magnesium 2-3.1, nickel 1-4.2, iron 0.02-1, zirconium 0.02-0.25 %, copper 0.05-0.3 %. Also, temperature of equilibrium solidus of material is as high as 550°C and hardness is as high as 180 HV. Alloy has a structure corresponding to matrix formed with solid solution of aluminium with uniformly distributed disperse particles of secondary discharges in it and particles of aluminides containing nickel and iron of eutectic origin uniformly distributed in matrix. Also, alloy contains matrix and aluminides at the following ratio, vol % aluminides containing nickel and iron 5.0-6.3, matrix - the rest.

EFFECT: production of new high-strength alloy thermally hardenable and designed both for fabrication of shaped casting and of deformed semi-products.

4 cl, 5 tbl, 4 ex

FIELD: metallurgy.

SUBSTANCE: product consists of following components, wt %: Zn 9.0-14.0, Mg 1.0-5.0, Cu 0.03-0.25, Fe <0.30, Si <0.25, Zr from 0.04 to less, than 0.3 and one or more elements chosen from group consisting of: Ti <0.30, Hf <0.30, Mn <0.80, Cr <0.40, V <0.40 and Sc <0.70, random elements and impurities, each <0.05, totally <0.15, and aluminium - the rest. The procedure for fabrication of product out of aluminium alloy consists in casting an ingot, in homogenisation and/or in preliminary heating the ingot upon casting, in hot treatment of the ingot into preliminary finished product with one or more methods, chosen from the group including rolling, extrusion and forging. Not necessarily, the preliminary treated product can be heated or hot treated and/or cold treated to a required shape of a blank; further formed blank is subjected to heat treatment to solid solution, to hardening blank heat treated to solid solution; not necessarily, hardened blank can be stretched or compressed, or cold treated by other way to stress relief, for example, by levelling sheet products or artificial ageing, till obtaining a required condition.

EFFECT: product with reduced tendency to forming hot cracks and with improved characteristics of strength, fracture toughness and hardness over 180 HB at artificially aged state.

32 cl, 6 tbl, 6 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to deformed alloys of aluminium-zinc-magnesium-scandium system and to procedure for their production. Aluminium alloy contains from 0.5 to 10 wt % Zn, from 0.1 to 10 wt % Mg, from 0.01 to 2 wt % Sc, at least 0.01 wt % at least one alloying additive chosen from Ag at amount of up to 1 wt % and Sn at amount of up to 0.5 wt %, aluminium and unavoidable additives - the rest. The procedure consists in production of the said aluminium alloy, in homogenisation, in extrusion, in treatment for solid solution, in quenching, in straightening with drawing and in ageing.

EFFECT: alloys possess good qualities such as relatively high strength and excellent corrosion resistance.

33 cl, 3 dwg, 4 tbl

FIELD: metallurgy.

SUBSTANCE: method involves ingot casting with the following composition, wt %: Zn 6.0 - 11.0, Cu 1.4 - 2.2, Mg 1.4 - 2.4, Zr 0.05 - 0.15, Ti <0.05, Hf and/or V <0.25, optionally Sc and/or Ce 0.05 - 0.25%, optionally Mn 0.05 0.12%, and inevitable impurities and aluminium is the rest, homogenisation and/or pre-heating of ingot after casting, hot deformation processing of ingot so that pre-processed product is obtained, heating of pre-processed product and either hot rolling of heated product to final thickness, or hot rolling and cold rolling of heated product to final thickness, heat treatment for solid solution and hardening of heat-treated product for solid solution, optional tension or compression of hardened product and optional ageing of hardened and optionally tensed or compressed product to the desired state; at that, rolled product at its final state has in fact fully non-recrystallised microstructure at least in position T/10.

EFFECT: product has increased yield point at compression and high specific energy of crack propagation, and improved viscosity and corrosion resistance properties.

21 cl, 6 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: aluminium-based alloy contains the following, wt %: zinc 0.5-0.7; titanium 0.1-0.13; silver 1.1-1.3; nickel 0.25-0.5; copper 0.15-0.25; cobalt 0.7-0.9; aluminium - the rest.

EFFECT: alloy is characterised with increased strength.

1 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy of protecting alloys on base of aluminium and can be implemented at production of protectors for aluminium heat exchangers on airplanes, sea and river vessels, domestic heaters and also fuselages of hydroplanes and vessels out of aluminium alloys for protection from corrosion. Protecting deformed alloy on aluminium base contains following components, wt %: zinc 1.8-3.0, magnesium 0.4-0.8, silicon 0.3-0.6, tin 0.03-0.07, indium 0.06-0.07, aluminium - the rest.

EFFECT: production of protecting alloy possessing upgraded mechanical properties which facilitates fabrication of protectors of various shape, small dimensions and big length.

2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to deformed thermally hardened high-tensile aluminium alloys Al-Zn-Mg-Cu designed for fabrication of all kinds of deformed semi-finished products, including thin sheets used in aircraft and machine engineering and other branches of industry. Deformed alloy on base of aluminium and an item out of it contain the following components, wt %: zinc 2.5-4.0, magnesium 4.1-6.5, copper 0.2-1.0, iron to 0.25, silicon to 0.15, scandium 0.005-0.3, zirconium 0.005-0.25, nickel and/or cobalt to 0.1, titanium to 0.15, boron and/or carbon to 0.05, at least one element out of group: hafnium to 0.15, molybdenum to 0.15, cerium to 0.15, manganese to 0.5, chromium to 0.28, yttrium to 0.15, vanadium to 0.15, niobium to 0.15, aluminium and unavoidable impurities - the rest, also ratio of Mg contents to Zn contents is more or equal to 1.1.

EFFECT: production of alloy and items out of it possessing raised strength properties at simultaneous increased wear-resistance, reduced rate of crack growth, increased durability of welded connections and reduced density, which results in increased resource and reliability of items operation and in reduced weight of structures.

3 cl, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to aluminium-based alloys which can be applied in dishware and coin production. Aluminium-based alloy contains, wt %: zinc 1.3-1.8; titanium 0.01-0.015; silver 1.3-1.8; nickel 1.3-1.8; cobalt 1.3-1.8; indium 0.2-0.3; the rest is aluminium.

EFFECT: production of alloy of enhanced hardness.

1 tbl

FIELD: metallurgy.

SUBSTANCE: particularly it concerns alloys on aluminium basis, which can be used in automotive industry. Aluminium-based alloy contains the following components, wt %: zinc 2.0-2.5; antimony 0.01-0.015; titanium 0.01-0.015; boron 0.007-0.009; beryllium 0.001-0.002; cobalt 0.6-0.9; the rest is aluminium.

EFFECT: production of alloy of enhanced hardness.

1 tbl

FIELD: metallurgy.

SUBSTANCE: particularly it concerns alloys on aluminium basis, which can be used in automotive industry. Alloy on aluminium base contains the following elements, wt %: zinc 2.0-2.5; antimony 0.01-0.015; titanium 0.1-0.15; boron 0.007-0.009; beryllium 0.001-0.002; copper 0.1-0.15; silver 0.1-0.15; cobalt 0.2-0.3; the rest is aluminium.

EFFECT: production of alloy of enhanced hardness.

1 tbl

FIELD: metallurgy.

SUBSTANCE: aluminum based protective alloy comprises, in mass %, 4-5 of zinc, 0.01-0.06 of indium, 0.01-0.1 solder, 0.01-0.1 of zirconium, and aluminum the remainder.

EFFECT: enhanced corrosion protection.

2 tbl

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