Manufacturing method of cold-rolled pipes from alpha- and pseudo-alpha-alloys based on titanium

FIELD: metallurgy.

SUBSTANCE: manufacturing method cold-deformed pipes from α- and pseudo-α-alloys based on titanium involves melting of an ingot, forging of an ingot in β- and α+β-region with ending of forging in α+β-region into an intermediate shell with forging reduction of 2 to 3; piercing is performed at the temperature that is by 30-50°C higher than Tpp, by multiple-cone rolls and a mandrel with the specified geometry with water supply to a deformation zone, rolling of the shell is performed at the temperature that is by 10-90°C lower than Tpp; straightening of the pipe shell is performed at the temperature of 350-400°C, cold rolling is performed with drawing coefficient of 1.5-4.5 at several stages by alternation with intermediate annealing processes at the temperature equal to 600-750°C, and further heat treatment with the ready dimension at the temperature of 580÷650°C.

EFFECT: high mechanical properties of manufactured pipes, as well as high quality of pipe surface.

4 dwg, 3 tbl

 

The invention relates to pipe production, namely the cold rolling of tubes from α - and pseudo-α-alloys based on titanium. The invention can be used for the manufacture of products intended for use in various fields of national economy, such as nuclear power, shipbuilding, aviation, mechanical engineering, chemical industry, etc.

Cold rolling of tubes has a number of advantages in comparison with the extrusion and hot rolling, the most important of which are:

(a) receiving tubes with precise geometric dimensions and especially with small eccentricity of the outer diameter relative to the inner;

b) high quality surface tubes;

in) high yield;

d) receiving the pipe with the ratio of the diameter to the wall thickness of 150:1 or more;

d) a high degree of metal deformation per pass (50-60%);

(e) achieve a significant hardening of the metal pipe during rolling due to compression as the diameter and wall thickness, etc.

Billet for cold rolling of the hot-deformed pipes serve the tubular stock.

The complex properties of titanium alloys as structural materials for the manufacture of pipes of particular technical and economic interest note (Ostrenko V. J. and Tr.�would of titanium and its alloys. - M.: metallurgy, 1987, 60 p.): low density in comparison with steels, high mechanical properties, high level of special characteristics (heat resistance, creep, creep strength, low cycle fatigue, fracture toughness, erosion and cavitation resistance, low induced radiation, etc.), corrosion resistance, processability.

The structure of alloys based on titanium defines the most important quality criteria of semi-finished products, has a significant diversity and extraordinary influence on mechanical properties. The peculiarity of pipes manufactured from alloys based on titanium is that the workpiece for the production of ingots are obtained by vacuum arc melting, in which the processes of melting, casting and solidification combined and separate control them is almost impossible. There is a significant overheating of the melt and form a coarse-grained structure of ingots, with significant heterogeneity in the cross section and coarse-grained lamellar microstructure. This makes them highly reduced deformability and low complex performance properties of products.

To improve the technological and operational properties required in the formation of fine-grained (grain size of the phases is not more than 150÷200 μm) of the microstructure. �besides, achievement in the semis of structurally homogeneous condition, it is important to assess the quality of pipes methods of ultrasonic testing, which is widely used in their manufacture. In the case vysokotirazhnoj and grain structure of titanium alloy when conducting ultrasonic testing significantly reduced the level of acoustic noise, increases the marginal sensitivity of the method, limited to these noises, and the material becomes more "transparent", i.e. having a minimum level of structural interference that creates the possibility of defects minimum size. This implies the extension of the work products, and, consequently, reducing the cost of machines and aggregates by use of products with defects of the correct size.

A method for manufacturing cold-deformed tubes of two-phase alloys based on titanium (Patent RF №2463376, IPC C22F 1/18, WV 3/00, publ. 20.12.2011), which includes ingot smelting, forging ingot in β-region or β - and α+β region with the end of the forging in the α+β region in the intermediate workpiece with a given ukonom. The intermediate preform was prepared ukonom not less than about 1.35, from the intermediate workpiece is made of a checker, pressed into the tubular workpiece and thermoablative at a temperature of 30-40°C below the temperature TPPand then carry out a rolling t�abnoy billet intermediate surface treatment, etching and heat treatment. The hood when rolling is determined by a specified formula. Received the pipes are characterized by high physical and mechanical properties due to the exclusion of education intergranular microcracks.

The disadvantages of this method is that the action of this method is narrowly specialized and confined to the production of pipes of two-phase titanium alloys. In addition, the rolling of cold-deformed tubes made from extruded pipe blanks, which are characterised by an increased metal consumption (by 15-30% compared with rolling) as a result of drilling the center hole before pressing operation and availability of the press residue, insufficient dimensional accuracy, in particular the varying wall thickness, the presence of deep scoring on the surface. Also a limiting factor in the production of hot-pressed to the workpiece is limited by the length of the billet during the extrusion.

A method for manufacturing tubes of non-ferrous metals and alloys (Russian Federation Patent No. 2048219, IPC WV 23/00, WV 3/00, WV 19/02, publ. 20.11.1995) is a prototype that provides hot screw firmware and rollers on the mandrel, in a three-roll calibers formed mnogogolosnyj the rollers, with the angle of inclination of the conical generatrix to the rolling axis at the entrance to the caliber 7-25° more than first�d toe of the mandrel, with compression on the input portion comprising 0.3 to 0.8 times the compression before the toe of the mandrel. The method also includes rollers stitched liner in rolls, having two crimp section (comb), separated by intermediate areas of calibration and rolling, and the angle of inclination of the generatrix to the rolling axis of one of them on 1,5-5,0° is smaller and the other larger than the angle of inclination of the generatrix of the input section of the piercing rolls to the rolling axis. The method allows to increase the yield and to improve the stability of the process in the processing wirausaha metals.

The disadvantage of this method is unstable primary and secondary grip the workpiece when the firmware, because of the angle of the inlet cone 4-8°. The geometric shape of the mandrel is not optimal, since it does not fully accounted for the greater tendency of titanium alloys to stick and tear and their low thermal conductivity. As a result, the surface of the mandrel having a large friction force, under the influence of which is an intensive heating of the metal, to withstand technological temperature range during piercing of billets of titanium alloys, as well as the intensive wear of the surface of the mandrel. The result is a buildup pressed (sew) of metal on the surface of the mandrel, causing not�stabilnosti flashing process, the formation of defects on the workpiece surface and the distortion of its geometrical dimensions, these further defects are inherited in subsequent operations and can lead to marriage. Method does not regulate thermal deformation parameters of the manufacturing process of non-ferrous pipes, in particular from alloys based on titanium, which does not guarantee receipt of the microstructure with the required quality.

The object of the invention is:

- a method of processing α - and pseudo-α-alloys based on titanium, allowing to get in the pipes of fine-grained (grain size less than 100 microns) microstructure;

- achieving a structurally homogeneous state in the finished product, providing transparency for ultrasonic quality control of semi-finished products and products;

- improve the surface quality and geometric precision manufactured tubes;

- improved stability of the technological process;

- quick change from one size to another;

- increase tool life.

The technical result is achieved by carrying out the invention, is the creation of an economic process for the manufacture of pipes from α - and pseudo-α-titanium alloys, which are combined steps of forming the geometric dimensions and surface quality products with �riesame the regulated formation of the microstructure, providing high technological and operational properties of the products.

Said technical result is achieved in that in the method of manufacturing a cold-rolled pipes from α - and pseudo-α-alloys based on titanium, including ingot smelting, forging ingot in a cylindrical billet for several transitions with alternating deformation in β and (α+β)-fields, and the last transition of the forging is carried out in (α+β)-region, machining, receiving tubular billet deformation, editing, annealing, surface treatment of pipe billets, cold rolled with intermediate finishing and finishing operations edit forging of the ingot in a cylindrical billet finish ukonom from 2 to 3 after heating in (α+β)-area piercing and rolling of lead in a single setup, the firmware is carried out at a temperature of 30-90°C above the temperature of polymorphic transformation (CCI) mnogogolosnyj the rollers, the angle of inclination of the input generatrix of the cone is equal to 5-1°, calibrating phase 3-1°, plot vanishing 2-1° on a water-cooled mandrel with a crimping sleeve consisting of conical and spherical plots, with constitutive radius R of the spherical section of the mandrel, calculated by the formula:

where d0- he steers the diameter of the mandrel, mm,

the diameter of the nose of the mandrel is equal to 2±10 mm, in the nose there is a hole from which the deformation zone to supply water under pressure from 1.0 to 2.0 MPa, and the between the surfaces of deformable metal and the mandrel is formed steam the shirt, subsequent rolling tubular blanks is carried out after the cooling-down in air to a temperature of 10-90°C below the CCI, the edit pipe billets produced at a temperature of 350-400°C, subsequent oxidative annealing at a temperature of 600±20°C, cold rolling is performed with the elongation factor of 1.5-4.5 in several stages, alternating with an intermediate annealing at a temperature equal to 600-750°C, and heat treatment on the finished size in vacuum resistance furnace at a temperature of 580÷650°C.

The invention is illustrated by drawings, where Fig.1 shows mnogokolesny swath of Fig.2 - water-cooled mandrel used in the firmware of Fig.3 - microstructure of cold rolled pipe ø 50×5 mm from the pseudo-α-alloy PTM, Fig.4 - microstructure of cold rolled pipes of α-alloy VT1-0 size Ø 51 mm×4.5 mm.

The invention is based on the fact that when thermo-mechanical modes of the proposed treatment, the formation of the geometry of the product agreed with the regulated processes of recrystallization and phase transformations in the blanks from α - and pseudo-α-alloys based on titanium, in which is formed a fine-grained microstructure with high �the degree of homogeneity.

Forging of the ingot in the rod at a temperature of β-region on the first passages destroys cast structure. Subsequent forging in the (α+β)-areas with a total ukonom 2 to 3 destroys high angle grain boundaries so-called "semihot hardening", during which the metal gets enough energy, contributing to the process of recrystallization during subsequent processing slab heating to temperatures of β-region.

The obtained cylindrical workpiece is heated to temperatures above CCI for 30-90°C (β-region) and producing operation of the firmware through holes, with the following positive factors:

1. Deformation in the β-region at a temperature above the CCI 30-50°C after performing the previous operations of forging is accompanied by recrystallization structure with grain refinement.

2. Deformation shape change occurs under favorable temperature conditions, since the metal in the β-region has a good supply of plasticity.

It is known that titanium alloys have a low coefficient of friction at a temperature of firmware, smaller inertial forces due to the lower specific weight and tend to be broadening, and therefore, there are preconditions for the emergence of an unstable process.

To ensure a stable process of firmware pulling efforts provided mnogogolosnyj rolls (Fig.1), to�which the angle of inclination of the input generatrix of the cone is equal to 1 5 -1°, calibrating phase 2 is $ 3-1°, plot vanishing 3 is equal to 2-1°. This geometry is chosen empirically and provides sufficient pulling force on the contact surface of the rolls to overcome the resistance of the metal, and the vanishing of the rear end of the sleeve on the gage section of the mandrel.

The main deformation of the metal is carried out at the site of breakdown of the cone mandrel. Profile crimp cone mandrel determines the nature of changes in the wall thickness of the workpiece along the length of the deformation zone. For optimum distribution of strain along the length of the deformation zone was designed water-cooled mandrel, which has a compression cone consists of two zones: spherical 4 and 5 conical (Fig.2). The plot of the mandrel with a tapered profile of the mandrel provides private compression wall, which increases in the course of rolling. With the increase of the private compress the walls of the increment of the diameter of the pipe by cross rolling is increased. So by the end of the deformation of the metal substantially departs from the mandrel, which ensures the vanishing of the sleeve. Forming the radius of the spherical section 4 of the mandrel is calculated by the formula:

where d0- he steers the diameter of the mandrel.

Experimentally it was determined the optimal diameter of the nose of the mandrel 5, which is achieved sravnitel�but a small axial resistance and a high durability. This diameter was equal to 20 mm. Also in the nose of the mandrel has openings 6 for supplying water which is under pressure from 1.0 to 2.0 MPa in the deformable cavity between the metal and the surface of the mandrel. The water pressure serves to maintain the optimal temperature. This produces steam "shirt", which not only protects the metal from overheating, but also protects the surface of the mandrel from deposition of metal, thereby improving the quality of internal pipe surface. In the process of cooling-down stitched billets before rolling to a temperature of at 10-90°C below the CCI occurs in alloys polymorphic β→α-transformation, α-phase is in the form of plates. During rolling of α-plates undergo deformation. The shape varies from straight to curved. The curves α-plates, and the presence in the structure of a large number of twins and shear bands, the beginning of the dynamic processes or metadynamic recrystallization provides a favorable state of the metal for subsequent annealing tubes.

After the operation of rolling of the tubular billet is subjected to edit at a temperature of 400-450°C. At this temperature for α - and pseudo-α-alloys have creep, sufficient for effective correction of errors of geometric shapes.

Hot rolled pipe merchantable�the mechanical process on the outer and inner surfaces to remove defects and gas-saturated layer after hot deformation. Next, the workpiece is subjected to oxidative etching and annealing at a temperature of 600±20°C to ensure a sufficient level of metal plasticity, as well as education on the workpiece surface oxide layer during cold rolling acts as a "podmazochnaja" layer that ensures no buildup of metal on the surface of the gauges during cold rolling and the mandrel. Cold rolling is carried out with the elongation factor from 1.5 to 4.5 for several transitions. This range hood is due to the receipt of a predetermined geometric dimensions of the product performing a process of recommendations for cold-formed titanium alloys without breaking. In between cold rolling pipe is etched, if necessary - sandblasted (possibly polishing) to remove from the pipe surface defects that could be formed in the process of cold rolling, annealing at a temperature of 740-760°C. Annealing between cold rolling and the final amount needed to eliminate internal stress, reduce the hardness and increase ductility of the metal. On the finished size will conduct a final annealing in a vacuum furnace at a temperature of 700-780°C. the Annealing is performed in a vacuum furnace in order to avoid the absorption of metal and to provide the required level content� of hydrogen.

The invention is illustrated by concrete examples of manufacturing cold rolled pipes.

Example 1. Made of cold-rolled pipe size ø 50×5 mm titanium pseudo-α-alloy PTM on compliance with requirements THAT 14-3-820-79, CCI=935°C.

Pipe produced according to the process scheme:

Ingot→forging in β-region for several transitions→forging in the (α+β)-region, Forging reduction=2÷3, T=CCI-30°C→fur. processing width: 130 mm→zacentrus blanks→heating T=CCI+30-50°C→firmware on PVP ⌀100×width: 64×18 mm→reeling at T=CCI-10-90°C size width: 88×⌀54×17 mm→edit at a temperature of 400-450°C→fur. machining (turning, boring) ø 85×⌀56×14.5 mm→etching→annealing T=600°C, 60 min→cold rolling width: 65×ø 48×8.5 mm (exhaust 2,13)→etching→annealing T=760°C, 60 min→cold rolling ⌀50×⌀40×5 mm (exhaust 2,09), edit.

Mechanical properties are shown in table 1. Also the pipes have passed tests for flattening before receiving clearance between splashimage surfaces N=35,405 mm.

Table 1
No. sampleσ0.2MPa, kgf/mm2σinMPa, kgf/mm2δ, %σ0.2MPa, kgf/mm2 σinMPa, kgf/mm2
Test temperature of 350°C
145257527,5232315
(46,1)(58,6)(23,6)(32,1)
244857525,2241317
(45,1)(58,7)(24,5)(32,3)
344157225,2232315
(44,9)(58,3)(23,7)(32,1)
444557223,8228313
(45,4) (58,4)(23,2)(31,9)
Requirements specifications THAT 14-3-820-79382480-66720176245
(39)(49-68)(18)(25)

Geometry requirements of the pipes are given in table 2.

Table 2
Diameter of pipe, mmTolerances on the outside diameter of the pipe. The increased accuracy of productionWall thickness, mmMaximum deviations of the wall thickness of pipes. The increased accuracy of production
Field tolerance, mm beyond 14-3-820Actual field tolerance, mmField tolerance, mm beyond 14-3-820Actual field tolerance, mm
505
of 49.5-50.5 per49,8 of 50.34,5-5,54,7-5,2
Compliance with THE 14-3-820ACC.Compliance with THE 14-3-820ACC.

In Fig.3 shows the microstructure of cold rolled pipe ø 50×5 mm from the pseudo-α-alloy PTM in the longitudinal direction at magnification ×200. The grain size d=0,95-2.36 microns.

Example 2. The manufacture of pipes of alloy VT1-0 size ⌀51×4.5 mm for compliance with the requirements of GOST 22897-86. CCI=920°C.

Pipe produced according to the process scheme:

The ingot width: 740 mm→forging bar width: 140 mm β-region→machining to ø 130 mm→zacentrus billet→heating T=990-1010°C→piercing and rolling mill PVP 40-80 width: 88×⌀54×17 mm→edit→machining (turning, boring) ⌀to 85.5×ø 56 x 14,75 mm.→etching→annealing T=700°C→cold rolling to size width: 65×ø 48×8.50 mm→etching→annealing T=700°C→cold rolling on the size ⌀51×ø 42×4.5 mm→etching→annealing in a vacuum furnace T=650°C→edit.

Mechanical properties are shown in table 3.

Table 3
No. sample σ0.2MPa, kgf/mm2σinMPa, kgf/mm2δ, %
134349124,6
(49,73)(71,2)
235048828,6
(of 50.75)(70,76)
Requirements specifications GOST 22897-86216343-56824
(22)(an excerpt) p. 35-58)

Also the pipes have passed tests for flattening before receiving clearance between splashimage surfaces N=35,45 mm.

In Fig.4 shows the microstructure of the cold rolled pipes of α-alloy VT1-0 size ⌀51×4.5 mm in the longitudinal direction at magnification ×200. The grain size d=7,5-8,0 ám.

The obtained pipe according to its mechanical properties and geometrical parameters exceed the requirements of regulatory and technical documentation, the technology is based on using standard process equipment, provide�Ecevit stability and fast reconfiguration of the production process of one standard size to another, creates favorable conditions of operation of the tool, and obtained on the finished product vysokooborotnye and the fine grain titanium alloy allows you to limit the level of structural noise in the ultrasonic inspection process.

A method of manufacturing a cold-rolled pipes from α - and pseudo-α-alloys based on titanium, including ingot smelting, forging ingot in a cylindrical billet for several transitions with alternating deformation in β and (α+β)-fields, and the last transition of the forging is carried out in (α+β)-region, machining, receiving tubular billet deformation, editing, annealing, surface treatment of pipe billets, cold rolled with intermediate finishing and finishing operations correction, wherein the forging of the ingot in a cylindrical billet finish ukonom from 2 to 3 after heating in (α+β)-region, receive the tubular stock is carried out by piercing and rolling a single setup, the firmware is carried out at a temperature of 30-50°C above the temperature of polymorphic transformation (CCI) mnogogolosnyj the rollers, the angle of inclination of the input generatrix of the cone is equal to 5-1°, calibrating phase 3-1°, plot vanishing 2-1° on a water-cooled mandrel with a crimping sleeve consisting of conical and spherical plots, forming a spherical radius R�about plot of the mandrel, calculated by the formula:
R=4900+(d0-23,669)22sin(arctgd0-23,669140-3)
where d0- he steers the diameter of the mandrel, mm,
the diameter of the nozzle mandrel equal to 20±10 mm, and the holes in the spout to the deformation zone to supply water under pressure from 1.0 to 2.0 MPa with the provision of education steam jacketed between the surfaces of deformable metal and the mandrel, the subsequent rolling tubular blanks is carried out after the cooling-down in air to a temperature of 10-90°C below the CCI, the edit pipe billets produced at a temperature of 350-400°C, subsequent oxidative annealing is carried out at a temperature of 600±20°C, cold rolling is performed with the elongation factor of 1.5-4.5 in several stages, alternating with an intermediate annealing at a temperature of, is $ 600-750°C, and a final heat treatment on the finished size is carried out in vacuum resistance furnace at a temperature of 580÷650°C.



 

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FIELD: metallurgy.

SUBSTANCE: proposed method comprises hot forming of slab, hot rolling and teat treatment of plate, whereat hot forming if carried out in one step. Immediately after reaching required thickness in slab forming it is quickly cooled to the depth of 20-30 mm at the rate of at least 50°C/min. Subsequent hot lengthwise rolling at performed at first step in α+β-area by partial reduction with deformation degree εi varying from 3% to 5% to total deformation ε=25…30% with breaks between passes of 8 to 12 s. At second step, it is performed in β-area from heating temperature determined by definite formula. At the next step rolling is performed in α+β-are with breaks and heating in lengthwise or transverse directions with total degree of deformation e after every break to 60%.

EFFECT: homogeneous fine-grain microstructure, high and stable mechanical properties, high precision, no surface defects.

FIELD: metallurgy.

SUBSTANCE: invention relates to production of thin sheets from ingot of pseudo-alpha titanium alloy. Proposed method comprises forming ingot of alloy Ti-6.5Al-2.5Sn-4Zr-1Nb-0.7Mo-0.15Si into slab and machining of the latter. Then, said slab is heated to temperature exceeding that of polymorphic transition, deformation and multistep rolling to semi-finished rolled stock with regulated total degree of deformation and degree of deformation in a pass. Sheets are stacked, stacks are rolled to finished size and subjected to multipass rolling with regulated total deformation, sheets are extracted from the stack and subjected to finishing.

EFFECT: high and uniform strength and plastic properties.

1 dwg, 2 tbl

FIELD: metallurgy.

SUBSTANCE: proposed method comprises smelting of alloy, making slab, machining its surface, hot, warm, and cold rolling, sintering and ageing. Smelted is pseudo-beta-titanium alloy with aluminium content not higher than 5.0 wt % and molybdenum equivalent No eq. ≥ 12 wt %, calculated by the following formula: Mo eq. wt % = %Mo + %Ta/4 + %Nb/3.3 + %W/2 + %V/1.4 + %Cr/0.6 + +%Fe/0.5 + %Ni/0.8 + %Mn/0.6 + %Co/0.9. Semi-finished 8-2 mm-thick rolled stock produced in hot and cold rolling is subjected, prior to cold rolling, to quenching at Tpt+(20-50°C) for 0.1-0.5 h with cooling. Cold rolling is performed to sheet thickness of 6-1 mm in signal-phase beta-state in two and more steps in several passes with 1-6%-reduction in one pass and total reduction at every step of 30-50%. Note here that intermediate quenching is carried out between said steps in conditions identical to quenching of semi-finished rolled stock before cold rolling.

EFFECT: high-quality rolled thin sheets.

5 dwg, 2 tbl

FIELD: process engineering.

SUBSTANCE: invention is intended for increasing quality of sheets and ruling out pollution originating in forming special magnesium alloys doped with high-toxicity light-volatile elements that form, in heating and forming, harmful oxides, and may be used in production of sheets for anodes of electrochemical current sources. Proposed method comprises placing round ingot in tubular shell, hearing the workpiece and its hot and warm rolling to requited sheet thickness.

EFFECT: higher quality of sheets and process efficiency.

5 tbl

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy, particularly, to forming semis from titanium alloy BT6 and may be used in machine building, aircraft engineering and medicine. Proposed method comprises annealing at 850°C with holding for an hour in furnace to create globular (α+β)-structure and multipass rolling combined with affecting semis to pulsed electric current with density of 50-200 A/mm2, frequency of 830-1000 Hz, pulse duration of 100-120 ms to ensure total true strain degree of e>1 and to form nanocrystalline structure in semi. Note that, after every pass, semi is water cooled. Higher forming capacity of alloy is provided for.

EFFECT: higher strength at optimum ductility.

5 cl, 1 dwg, 1 tbl, 1 ex

FIELD: process engineering.

SUBSTANCE: proposed method comprises making ingots or powder billets. The latter are subjected to hot thermo mechanical machining, including sandwich rolling and finish cold rolling. Foil material mechanical properties are stabilised and material structure is blended in sandwich rolling at semi-finished rolled stock thickness of 2-4 mm with premade fine structure wherein grain width does not exceed 10 mcm while its length makes 40 mcm. Sandwich is composed of a set of semi-finished rolled billet and two steel covering plates. Note here that top covering plate thickness is 1.4-1.8 times larger than that of bottom plate. Hot rolling of sandwich is started from 950±50°C in several passes with total deformation of 70-90%. After annealing at 920±70°C and sandwich disassembly, cold rolling of every billet is performed at total deformation of 40-70% with intermediate vacuum annealing at 920±70°C.

EFFECT: higher foil quality made from titanium aluminide-based alloys based on Ti2AlNb orthorhombic phase.

2 cl, 4 dwg, 2 tbl

FIELD: process engineering.

SUBSTANCE: invention relates to metallurgy, particularly, to production of 90-150 mm-dia tubes from superhard Al-Zn-Mg-Cu-system-based aluminium alloys to be used in aerospace engineering, oil-and-gas industry, and nuclear engineering. Method of production of 90-150 mm-dia tubes from superhard Al-Zn-Mg-Cu-system-based aluminium alloys comprises semicontinuous casting with modification of structure to grain size equal to dendritic parameter and stepwise casting blending. Note here that second stage temperature is cooled to that of production of 90-150 mm-dia tubes from superhard Al-Zn-Mg-Cu-system-based aluminium alloys to room temperature. Then machining for forming is performed followed by tube forming. Tubes are annealed at temperature of minimum stability of solid solution and held for 1-2 hours and cooled to 150°C. Note tubes are subjected to cold rolling, tempering, straightened and artificial ageing.

EFFECT: better mechanical properties, longer life.

6 tbl, 1 ex

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