What’s up guys?!?! This is Michael with Michael Talks Metal back for another talk on some Aluminum today.

Our last video introduced you to the numbering system that identifies the common alloy chemistry and what the alpha portion of the “temper” designation means.

Today we are taking a deeper dive into the subdivisions of the T tempers before we move on to talking about specific alloys in the 2xxx, 6xxx, and 7xxx series.

Common examples of alloy and temper….

2011-T3, 2024 -T4, 2024-T351, 7075-T6, 7075 – T73511…lots of numbers here.  What does it all mean?

All the heat treatable alloys are strengthened by precipitation hardening. Cold working can supplement the heat treatment in achieving the required properties as shown in some tempers. Cold work that does not affect the properties is not prohibited in other tempers.

A two step process that first creates a uniform distribution of the chemical elements  .. is called a  solution treatment.  This is done by heating the alloy to about 900 degrees F and then  quenching to cool rapidly, usually in water.

The second step….precipitation or ageing … allows some of the elements to form particles within the structure that results in strengthening the alloy.

In some alloys this can occur at room temperature and is termed naturally aged.  When the precipitation step requires heating its termed artificially aged.

Time and temperature for each step vary by alloy and are typically performed by the producing mill.

T1 temper indicates the alloy was cooled from an elevated temperature shaping process like hot rolling, then naturally aged resulting in a stable condition and not  subsequently cold worked to increase strength

T2 is like T1 but cold worked and naturally aged.

T3   solution heat treated, cold worked and naturally aged….Our 2011-T3 example is typically cold drawn and naturally aged in bar products.

T4  solution heat treated and naturally aged…2017-T4  would not require any cold work between solution treatment and ageing to achieve properties

T5  cooled from an elevated temperature shaping process and then artificially aged.  6063 – T5 extrusions would be aged after cooling from the extrusion temperature.

T6 solution treated and artificially aged…Our example of 7075-T6

T7  solution heat treated and stabilized… 7075-T7351 from our examples.

More on the extra digits in just a minute

T8  solution heat treated, cold worked, and then artificially aged. 2011-T8 would be an example here

T9  solution heat  treated, artificially aged and then cold worked

T10  cooled from elevated temperature shaping ,cold worked and then artificially aged.

An additional digit represents a variation of that temper…..so for example a T73 or T76 is a variation of a T7 temper or T62 is a variation of a T6

Wow… seems like we covered all  permutations in the first couple of digits after the “T”, but we often see even more numerals.   What the heck are they?

Glad you asked.

Add an additional “51” and it indicates stress relieved by stretching.

For example a T651 temper is aT6 that is stress relieved by stretching and T7351 is stress relieved T73.

add a ZERO and that T6510 is a T6 extrusion with only stretching for stress relief.  add a 1 instead of 0 and T6511 is an extrusion that may receive minor straightening in addition to the stretch for stress relief.

Looks like we have covered most of the “code” that describes the alloy and temper for the heat treatable alloys and as you can see there are a whole lot of requirements contained in that string.   Even more detail can be in the individual specification, so check the specs!     Twice or maybe thrice!

Hope you enjoyed the temper talk today! Tune in next week for more riveting discussion on Aluminum. If you made it this far, please consider subscribing. If you have missed any previous videos, click here. Thanks again for watching, this is Michael with Michael Talks Metal, OUT!