What’s up guys? Michael with Michael Talks Metal, back for the 150 th video about our favorite topic… metals and alloys.
Last week we showed a test report for an Aluminum 7075 alloy in a T7351 temper manufactured to AMS 4124.
In addition to the mechanical properties, we have something reported as “COND – % IACS” on the same line. COND for conductivity. Electrical conductivity.
What does electrical conductivity have to do with the mechanical properties?
The requirements for this temper ” T7351″ include a minimum for the mechanical properties, but it is also an “overaged” temper for increased resistance to stress corrosion. The additional aging at higher temperatures increases the electrical conductivity of the alloy.
The combination of satisfying the minimum strength requirements and a minimum conductivity requirement of 40 % IACS assure that the material will perform as required.
Sounds simple so far. Wait…. the test report shows 38.7 %.
When the conductivity is below 40%, we have to look at the yield strength.
If the conductivity is 38.0 to 39.9 and the yield does not exceed the 56.0 ksi minimum by more than 11.9 ksi; the product is acceptable. In our example, our yield strength is reported at 59.1 ksi and the minimum is 56.0 ksi , so we have conforming material.
Typically the conductivity is required to be measured on the sample used for tensile testing.
When there are multiple tensile tests, each sample is also tested for conductivity.
So what does IACS mean?
IACS is the International Annealed Copper Standard. Conductivity is then expressed as a comparative percentage of this arbitrarily selected standard.
Specifications and part requirements can alter what we have shown you today so for the 150th time CHECK THE SPECS!!!!! Twice So this is Michael with Michael Talks Metal, remember for other videos on aluminum alloys and tempers…check the website for more info www.michlinmetals.com
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