SU707373A1 - Method of thermal treatment of aluminium-lithium wased alloys - Google Patents

Description

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The invention relates to the metallurgy of non-ferrous alloys and can be used at metallurgical and machine-building plants in the manufacture of semi-finished products and parts made of aluminum alloys.

In recent years, great attention has been paid to the doping of aluminum alloys of various systems with lithium. The most widely researched and found .; industrial use of the alloy developed on the basis of the systems AG-Cu-Ll-Mn-Cd (VAD-23) and Al-Mg-Li (01420 Aluminum alloys with lithium are thermally hardened and alloyed and quenched with subsequent artificial aging.

Aluminum alloys with lithium (01420 and VAD-23) can be subjected to quenching and artificial aging according to the modes temperature 120 ° C, holding 12-48 hours and temperature, holding 1824 hours 1.

However, these modes, providing enhanced plasticity, do not provide: They have a maximum level of mechanical properties.

The optimal mode of artificial aging j provides them with the maximum strength for alloys with lithium; the temperature is 160 ° C + 170 C and the duration of the retention is 10-24 h 2.

However, such a mode of artificial aging, which ensures the maximum strength of the alloys, does not ensure the stability of the mechanical properties and does not last much longer. A longer cycle of artificial aging leads to an increase in energy consumption and a decrease in the capacity of thermal units.

The purpose of the invention is to stabilize the mechanical properties and shorten the heat treatment cycle for the alloy.

This is achieved; by applying two-step aging: the first 0 step at a temperature of 145-155 C for 3-4 hours and the second step at a temperature of 180-19 degrees for 3-4.

The two-stage mode of artificial aging (5) provides a reduction of 5 the duration of the heat treatment cycle. In addition, the aging according to the proposed mode leads to a more uniform and more dispersed decomposition of the solid solution through the body and 0 grain boundaries and, as a result,

.- "J- .-. To more stable mechanical bonds with some increase in plasticity. nosti. Example. Samples of the profile size of mm from the alloy of the Al-Mg-Li system (01.420) were thermo-treated according to the standard mode providing maximum strength: quenching - heating temperature 450 + 5 ° С, holding for 45 min, air cooling and artificial aging at temperature 170 + 5s for 1b hours, as well as according to the proposed mode: quenching is the same, artificial test is the first step at a temperature in the range of 145-155 ° C for 3-4 hours and the second step at a temperature in the range of 180-190 ° C for 3-4 hours

Artificial mode

Aging system

Known (prototype) 165С (16 h)

Offered.

 (3 hours) + 180s (3 hours) 155 ° С (3.5 hours) + 185С (3.5 hours) 3) 150С (4 hours) + 190s (4 hours) 1550s (4 hours) (3.5 hours ) 1450s (3 hours) + 190 ° С (3 hours) 155 ° С (3 hours) + 190С (3 hours). 145 ° С (3 h) + 190 ° С (4 h) 155 ° С (4 h) (4 h) Known (prototype) 170 ° С (16 h)

-Li Offered 145С (3 hours) + 180С (3 hours)) 155s (3,5 4) -fl85 ° C (3,5 hours)

 (4 hours) +190 С

 (4 h) (4 h) 155 ° С (4 h) -И85С (3.5 h) 155 ° С (3 h) (W h) 145 ° С (3 h) + 190 s (3 h) (3 h) (4 h) (4 h) + 190 ° C (4 h)

Mechanical properties

 2 G, I

KGDF kg / mm I%

49-52 3-6

5-7

51-52

The same the same ii

7-11

31-35

9-11

33-35 Ditto

(4 hours)

P

 Example 2: Samples from a sheet of 4x1200x2000 mm in size from an alloy of the Al-Cu-U-Mn-Cd - () system were thermally processed according to the standard mode providing maximum strength: quenching - heating temperature 520 + 5С, over 60 min, cooling in water 4 with a temperature of 20 ° C and artificial aging at a temperature of 165 + 5 C for 16 h, and also according to the proposed mode: hardening is the same, artificial aging is the first step at a temperature in the interior of 145-155 ° C , flow- 3-4 hours and the second stage at a temperature in the range of 180-190 ° C for 3-4 hours. The results of the mechanical tests of the samples from examples 1 and 2 are shown in the table.

As can be seen from the table, the use of the proposed method for the heat treatment of aluminum alloys based on AlyMini with lithium allows one to shorten the cycle of artificial aging by 1.5–3 times and to obtain more stable maximum

properties at the same level with some beating of plasticity in comparison with t by treatment according to the well-known single-stage aging regime.

The application of the proposed method allows the doK | | atit time of production of industrial aluminum semi-finished products and increase the throughput of thermal units. invention The method of heat treatment of alloys based on aluminum with lithium, including quenching and artificial aging, characterized in that, in order to stabilize the mechanical properties and shorten the heat treatment cycle, aging is carried out in. two steps, first at 145-155С for 3-4 hours, then at 180-190 seconds for 3-4 hours. Sources of information taken into account during the examination 1. Industrial deformed sintered and cast aluminum alloys. Reference Manual, 1972, p. 22b. 2. Industrial deformable sintered and cast alloys. Cnpaifeo4Hoe manual. 1972, p. 213-215.

Claims (1)

Claim The method of heat treatment of aluminum-lithium-based alloys, including hardening and artificial aging, characterized in that, in order to stabilize the mechanical properties and reduce the heat treatment cycle, aging is carried out in. two steps, first at 145-155 · ^ for 3-4 hours, then at 180-190 ° С for 3-4 hours