Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

5.1.5.9 Heat treatment of aluminium alloys and its verification
During age hardening of aluminium or titanium alloys, the hardness and
conductivity of the material change simultaneously so that the degree of
hardening may be obtained by measuring the conductivity of the test
specimen and comparing it with a standard of that material with a known
hardness. The operator must be aware of the effects of discontinuities and liftoff
on the meter readings. As can be seen from FIG.5.21 a typical conductivity
of 35% IACS could have a Rockwell B hardness of either 20 or 85, from this
we can see that conductivity measurements for heat damage must be
accompanied with hardness testing to confirm true condition. In the
manufacturing industry, conductivity alone can be used to confirm material
Temper after heat treatment.
Charlie Chong/ Fion Zhang