Full hardening press for aluminum profiles

For thermally hardenable alloys 6xxx reinforcing components are magnesium and silicon. therefore, to achieve the maximum potential of the alloy for hardening by aging, natural or artificial, in pressed profiles from 6xxx series alloys, for example, alloys 6060 and 6063, need to be sure, that before the aging operation, the solid solution contains the maximum possible magnesium and silicon content for this alloy.

T6 temper – full hardening

The usual way to maximize magnesium and silicon, available to highlight hardening phases during aging, consists, speaking scientifically, in heat treatment of alloy to solid solution. This is usually called just quenching.. The goal of quenching is to, чтобы полностью перевести в твердый раствор алюминия все (Mg, Si)-частицы перед операцией старения.

For most alloys of the 6xxx series, the quenching heating temperature is in the range from 515 by 540 oC, with excerpt from 10 minutes to 1 hours depending on the thickness of the product and the type of furnace. Cooling after heating should be fast enough - in the air, compressed air, jets of water or immersion in water depending on the alloy, profile thickness and its shape. This is the condition of thermally hardened alloys., hardened with separate heating and then artificially aged is designated according to the international classification T6.

T5 state – incomplete hardening in the press

For all aluminum alloys of the 6xxx series and some alloys of the 2xxx and 7xxx series, the thermally hardened state T5 is provided, which is obtained by artificial aging profiles, which were accelerated cooled at the exit of the press.

Международные стандарты так и называют это состояние: «охлажденный с температуры горячего формования и искусственно состаренный». Our standards, for example, GOST 8617 and GOST 22233, называют профили в этом состоянии более определенно и слегка негативно: «неполностью закаленные и искусственно состаренные».

If there was no complete dissolution when pressing profiles, for example, magnesium and silicon in a solid solution of aluminum and / or cooling on the press was not fast enough, the, really, quenching will be incomplete. Therefore, the tensile strength requirements, for example, alloy 6063 in state T5 on 30 MPa below, than in the T6 condition.

Strength of aluminum profiles in T5 and T6 states

Strength aluminum alloys AD31, 6060 and 6063 in T5 states, Т6 (Т1 в отечественных обозначениях) при толщине стенки до 3 мм (для сравнения) можно выразить следующими «формулами», which follow from the requirements for them standard GOST 22233-2001:

  • для состояния Т6 (Т1):
    6060-T6 = 190 MPa
    АД31Т1(22) = 6060-Т66 = 6063-Т6 = 215 MPa
    АД31Т1(25) = 6063-Т66 = 245 MPa
  • для состояния Т5:
    6060-T5 = 160 MPa
    AD31T5 = 6063-T5 = 175 MPa.

State T66 differs from the usual state of T6 in increased strength due to special control of manufacturing technology of profiles.

Full hardening in the press – state T6

The practice of manufacturers of aluminum profiles has long been shown, that complete quenching of the alloy can be achieved not only after separate heating, but also directly on the press. Для этого необходимо обеспечить полное растворение всех (Mg2Si)-частиц в заготовке до или в ходе прессования и предотвратить образование новых частиц при охлаждении профиля. If such measures have been taken in the press, then after artificial aging a condition is achieved with a strength not lower than, and sometimes higher, than in the T6 condition.

T6 state during press quenching according to EN 755-2

The European standard EN 755-2 defines the requirements for the strength properties of extruded products, including, profiles. In tables with strength requirements for the part of thermally hardened alloys, the same note is present 5 для состояний Т6 (а также Т4 – для естественного старения): «Свойства могут быть получены путем закалки на прессе». To these alloys, which can reach the state of T6 during hardening in the press, all 6xxx series alloys apply, including the most “running” – 6060, 6063, 6061, 6082 and 6005, а также некоторые сплавы серии 2ххх (2007, 2011, 2017A i 2030) и серии 7ххх (7003, 7005 (аналог нашего 1915), 7020 and 7022). This entry is EN 755-2 recorded and "legitimized" the long-term practice of obtaining the strength properties of the T6 state during hardening in a press instead of more expensive hardening with separate heating. Thus, if the pressed products after quenching on the press and artificial aging satisfy the requirements for the strength properties of the T6 state, then it is assigned a state of T6, although formally hardening did not take place with separate heating, and in the press.

T5 and T6 states in GOST and DSTU standards

Domestic requirements for the mechanical properties of extruded aluminum profiles determine interstate standards GOST 8716 and GOST 22233-2001, а также украинский ДСТУ Б В.2.6-3-95 (ГОСТ 22233-93). По точности изготовления профили для ограждающих конструкций подразделяют на три типа: нормальной точности, повышенной точности и особой (прецизионной) точности. Normal accuracy generally corresponds to the accuracy of manufacturing general purpose profiles according to GOST 8617-81.

GOST 8617-81: состояния Т5 и Т1

Applies to general purpose extruded aluminum profiles made of AD0 grades, AD1, HELL and aluminum alloys, по сериям: АМц – Д1, D16, AK4, AK6 – AMg2, AMg3, AMg5, AMg6 - AD31, AD33, AD35, AB – 1915, 1925 GOST 4784, as well as some alloys according to industry normative and technical documentation. T5 state is already present in this standard., instead of T6, its domestic equivalent is applied - state T1.

GOST 22233-2001: состояния Т5, T6, T64, T66 and T1

Combines requirements for extruded aluminum alloy profiles AD31, as well as its international analogues - alloys 6060 and 6063 для ограждающих конструкций зданий (окон, facades, entrances to shops and t. P.), а также комбинированных («теплых») профилей из них. (Об особенностях химического состава сплавов АД31, 6060 and 6063 in GOST 22233-2001 look. here). GOST 22233-2001 include requirements for the mechanical properties of profiles in T5 and T6 states for international alloys 6060 and 6063, а также Т5 и Т1 (эквивалент Т6) для отечественного сплава АД31. При этом состояние Т6 идет в двух вариантах: «обычном» – T6 and “reinforced” - T66, as well as unmatched, with increased ductility – T64. Similarly, у состояния Т1 для сплава АД31 также есть два варианта: «обычное» Т1(22) – «усиленное»Т1(25).

ДСТУ Б В.2.6-3-95 (ГОСТ 22233-93): Т5 и Т1

Valid in Ukraine for extruded profiles made of alloys AD31 and 1915 for building envelopes, including, and in states T5 and T1. На комбинированные («теплые») профили в Украине действует отдельный ДСТУ Б В.2.6-30:2006.

GOSTs about hardening in a press for T6 state

Any notes, as in EN 755-2, о возможности получения состояния Т6 (или Т1) при закалке профилей на прессе в стандартах ГОСТ 8617-81, GOST 22233-2001 и ДСТУ Б В.2.6-3-95 (ГОСТ 22233-93) нет. Therefore, what our standards, unlike European EN 755-2, do not give a formal basis for obtaining profiles in T6 or T1 states directly by quenching on a press.

See. also Hardening aluminum alloys extrusion press