Tempers of aluminum alloys – important for welding


Inside the wrought and cast lots are two completely different types of aluminum alloys – thermally hardenable and thermally neuprochnyaemye. The former are able to increase their strength properties as a result of heat treatment (sequences of heating and cooling), and the second - no. This difference is very important when considering the impact. arc welding aluminum, more precisely – welding components from aluminum alloys.

Thermally unstrengthened aluminum alloys

Series 1xxx, 3xxx and 5xxx deformable aluminum alloys are thermally non-hardenable and can only be hardened by cold deformation, often called freaking. Series 2xxx, 6xxx and 7xxx deformable aluminum alloys are thermally hardenable. 4xxx series includes both heat hardenable, so thermally unstrengthened alloys. Cast alloys of 2xxx.x series, 3xxx.x, 4xxx.x and 7xxx.x are thermally hardenable. Hardening by hardening is not usually applied to cast alloys..

Thermally unstrengthened alloys achieve optimum mechanical properties as a result of hardening, that is, as a result of cold plastic deformation.

Thermally hardenable aluminum alloys

Heat-hardening alloys obtain optimal mechanical properties as a result of heat treatment, usually - quenching, quenching and artificial aging. When heated for hardening, the alloy is heated to an elevated temperature (about 530 ° C), to completely dissolve all alloying elements or components in aluminum. Then follows hardening., water or air, to obtain a supercooled alloy solution at room temperature.

Hardening is usually followed by aging.. Aging is the allocation of alloying elements and components from a supersaturated solution of an alloy, providing increase in strength properties. When heated for hardening, the alloy is heated to an elevated temperature (about, which is called natural aging, and aging at elevated temperatures, near 160 ° C, which is called artificial aging. Many thermally hardenable alloys are used in welded structures precisely in the state after quenching and artificial aging..

Symbol states aluminum alloys

The system of notation of various states of aluminum alloys indicates these states of the aluminum alloy material in the form of an extension to indicate alloy. State symbols include a series of letters and numbers, which immediately follow the alloy designation and are associated with a hyphen (dash), for example, 6061-T6, 6063-T4, 5052-H32 and 5083-H112.

The designation of the state of the aluminum alloy material begins with the letter H or the letter T. The letter H indicates a freewheeling, and the letter T is for thermal hardening.

The first number after the letter H indicates one of the four basic cold-worked states of the material:

  • H1 - Only chartered
  • H2 - Caked and partially annealed
  • H3 - Chipped and stabilized
  • H4 - Coated and varnished or painted.

The second digit after the letter H indicates the degree of autofrettage:

  • Hx2 - Quartered
  • Hx4 - Half Chipped
  • Hx6 - Three Quartered
  • Hx8 - Fully Chipped
  • Hx9 - Charted over full chartered

More information about harting, including, about the approach to it of domestic standards, can see here, and here.

The first digit after the letter T indicates one of ten basic thermally hardened states of the material:

  • T1 - Naturally aged after cooling from hot temperature molding (for example, pressing)
  • T2 - cured after cooling by hot temperature molding and then naturally aged
  • T3 - Tempered, caked and naturally aged
  • T4 - Hardened and Naturally Aged
  • T5 - Artificially aged after cooling from temperature hot forming process
  • T6 - Hardened and artificially aged
  • T7 - Hardened and Stabilized (over-aged)
  • T8 - Tempered, caked and artificially aged
  • T9 - Tempered, artificially aged and caked
  • T10 - Hot-formed after cooling from the temperature of the hot forming process and then artificially aged

Additional numbers may indicate residual stress relief., for example, Тх51 or Тхх51 (removal of residual stresses by tensile) or Тх52 or Тхх52 (removal of residual stresses by compression).