Aluminium T6 versus T651 — the difference.


Temper is a measure of a metal’s resistance to bending or kinking. In this post we look at the difference between T6 and T651. These tempers are bestowed by heating, quenching and cooling in a controlled way.

At Isizwe Metals we only stock T651.


There is no real difference in the mechanical properties of T6 and T651. The tempers, alloy composition and most metallurgical properties are similar. Both tempers have identical corrosion performance. The difference between the two is in the method of manufacture. The method has an effect on performance in certain applications.

T6 temper requires only solution heat treatment followed by artificial ageing. T651 is also heat treated and aged. But between the treatments the plate is stretched to flatten and relieve stresses. A plate gets quenched in water coolant after heat treating it. This is a complex process that leads to a high level of stresses induced into the plate. The process can distort the plate and create uneven flatness. In the case of the T651, the plate is stretched in a separate operation before ageing. The stretching removes all the quenched in stresses.
When the T651 plate gets machined it exhibits “post-machining stability”. It will not distort or buckle like the T6 as metal gets removed or the shape changed.

The T6 plate is not required to be stretcher levelled. And most often a roller levelling technique gets used to achieve an acceptable flatness. This process is much cheaper than stretching the plate. But does not relieve the quenching stresses. What it comes down to is the T6 plate’s temper can distort when the plate gets machined or cut. T651 is a safer general option.

Source: afsa.org.za

6082 specifications

Alloy 6082Isizwe-Metals_6082_Aluminium_Bridge

Outstanding Characteristics
Medium strength alloy with good corrosion resistance.

Standard Commodities
Plate; sheet; extrusions.

Typical Uses
For stressed structural applications, such as bridges, cranes, roof trusses, transport applications.Beer barrels; milk churns. Bridle plates for man cages and ore skips.

6082 Data Sheet PDF and information referenced from AFSA.org.za

7075 specifications

Alloy 7075Aluminium_7075

Outstanding Characteristics
Very high strength.

Standard Commodities

Typical Uses
Aircraft structures. Armaments – forgings.

7075 Data Sheet PDF and information referenced from AFSA.org.za

Returns / Refunds

At Isizwe Metals we strive for high standards of service. When placing an order keep in mind that our high speed saws offer tolerances of +/- 0.5 mm. If a mistake was made on our side we need to be notified within 7 days of you receiving the material.

If the mistake was made on your side we are unfortunately not able to accept returns. So please be careful when selecting your custom measurement.

Delivery / Collection

All orders are typically sent out within 3 – 6 working days. Once your material is with our courier company (SkyNet) you will receive a notification and be able to track your material. Delivery can take between 1 – 3 days depending on your location.

Please note we only deliver to the following major cities:

Cape Town
East London
Port Elizabeth
Richards Bay
If you select the collection option at check out and want to pick up the material at our warehouse you can. Or arrange a courier to collect it. You will receive a notification when the material it is ready for collection.

The address is 102 Plane Road, Spartan, Kempton Park, Johannesburg.

R100 Minimum Order Amount

We have a minimum order amount of R100. If you do not have this minimum in your cart you will be unable to continue with your transaction.

Payment / How To Order

Simply enter your measurements you require and follow the prompts on the form. We will then send you a confirmed quote with the banking details. After receiving the payment we will proceed with the cut and send it out for dispatch. Order from anywhere in South Africa and at whatever time you please. Quote Calculator

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