On states of aluminum profiles to visit and SNiPY

Tempers of aluminum alloys

Состояние алюминиевого сплава отражает историю обработки материала алюминиевого изделия или полуфабриката (деформационную и/или термическую). Химический состав сплава и его состояние однозначно определяют структуру материала и его механические свойства. Indicating products made of aluminum and aluminum alloys without specifying their condition does not make any sense!

In the current GOST 8617-81, GOST 22233-2001 and SNiP 2.03.06-85 (updated, SP 128.13330), Unfortunately, there is no uniform approach to the definition and designation of states for extruded aluminum profiles. Moreover, domestic designations differ from those accepted in international practice. Therefore, there is uncertainty and confusion (see. table and figure 1 below). This can lead to incorrect ordering of aluminum products., improper manufacture and incorrect delivery, especially when exporting and importing.

States of aluminum alloys in GOST 8617-81

States are applied:

  • Without designation - without heat treatment (hot-pressed);
  • M - annealed;
  • T - hardened and naturally aged;
  • T1 - hardened and artificially aged;
  • Т5 - not fully hardened and artificially aged.

States of aluminum alloys in GOST 22233-2001

For the AD31 alloy, the following states are applied:

  • T - hardened and naturally aged;
  • T1 - hardened and artificially aged;
  • Т5 - not fully hardened and artificially aged
  • Т1 (22) and Т1 (25) - hardened and artificially aged with increased strength.

For international alloys 6060 and 6063 the following states apply:

  • T4 - hardened and naturally aged;
  • T6 - hardened and artificially aged;
  • Т5 - not fully hardened and artificially aged
  • T64 – hardened and artificially aged [under-aged, approx. author];
  • T66 – hardened and artificially aged with increased strength.

States of aluminum alloys in SNiP 2.03.06-85

  • M - annealed;
  • T - hardened and naturally aged;
  • T1 - hardened and artificially aged;
  • T5 - not fully hardened and artificially aged.

Moreover, only in this SNiP there is one more state:

“T4 - not completely hardened and naturally aged”.

Such a state – “not fully hardened and naturally aged” -absent in GOST 8617 and GOST 22233. Therefore, it is difficult to order it from the manufacturers of aluminum profiles.. In GOST 22233 T4 designation is used in international “sense”, as "hardened and naturally aged" and only for alloys 6060 and 6063.

For a similar condition there is an international designation T1 (which coincides with the domestic designation T1 for the condition "hardened and artificially aged") - see. table.

About condition T5

В EN 515 it is defined as: "Chilled from hot deformation temperature and then aged".

In domestic documents, this condition is called "not fully hardened and artificially aged", which does not quite reflect the essence of the matter.

With proper technology control, the hot deformation temperature can be higher than the quenching temperature, and the alloy can reach full quenching when properly cooled from this temperature. In that, properly, is the essence of reaching the T6 state when quenching on an extrusion press.

About T4 states, T6, T64, T66

By definition of T4 state, T6 , Т64 and Т66 include hardening from separate furnace heating. However, in practice, for alloys 6060 and 6063 these states are obtained by press hardening. In this case, unlike the T5 state, produced, least, additional control of the temperature of the profiles at the exit from the matrix.

In the tables of the EN standard 755-2 in terms of mechanical properties for pressed products from most alloys of the 6xxx series and some alloys of the 2xxx and 7xxx series, the note clearly indicates, that these states can be achieved by press hardening (and not with separate heating) - see. Figure 2. The T5 state is also achieved by cooling the profiles on the press from the pressing temperature. However, in contrast to the T5 state, to achieve the T6 states, additional technology control is required, for example, control of the temperature of the profiles at the exit from the matrix.

Joint designation of alloy and condition

GOST 8617-81

Alloy designation and condition designation are separated by a dot.

for instance, for the AD31 alloy in the hardened and artificial state, the designation is used: АД31.Т1.

GOST 22233-2001 for alloy AD31 and SNiP 2.03.06-85

Alloy designation and condition designation are written together, without space.

for instance, for the AD31 alloy in the hardened and artificial state T1, the designation is used: АД31Т1.

GOST 22233-2001 alloys 6060 and 6063

Alloy designation and condition designation are written separated by a space.

for instance, alloy 6060 in the hardened and artificial state T6, the designation is used: 6060 T6.

Foreign regulatory and technical documents

In the European technical literature, the designations of the alloy and the state are used as with a space between them., for example, 6060 T6, and with a hyphen (no dash!), for example 6060-T6. standard EN 515, which gives definitions of all states, does not give any instructions on this.

In American documents, between the designation of the alloy and the condition, they put a hyphen (not a dash!), for example, 6060-T6.

In our opinion, the most convenient and unambiguous is the "American" version, i.e, for example, 6060-T6. .

conclusions

1) The simultaneous use of domestic and international designations of the states of aluminum alloys in various regulatory documents can cause confusion, a, exactly, wrong product order, improper manufacture and incorrect delivery.

2) It would be reasonable to:

  • completely switch to the international designation system for the states of aluminum alloys, for example, by EN 515;
  • when designating alloy and condition, put a hyphen between them, for example, 6060-T6;
  • introduce the international definition of the state T5: instead of “not fully hardened”, use: “cooled from the pressing temperature”;
  • for international states T4, T6, T64, T66 in GOST 22233 clearly indicate the possibility of achieving them by hardening on the press.

Table - Designations of the states of aluminum alloys in various regulatory documents (to increase – click on the table) sostoyaniya-tablica

 

sostoyaniya-gost-snip

Figure 1 - Designations of the states of aluminum alloys in GOST and SNiP
(for increase – click on the picture)

sostoyaniya-en755

Note with – Properties can be achieved by press hardening

Figure 2 - Table of mechanical properties in DIN EN 755-2
for extruded alloy profiles 6060
(for increase – click on the picture)