...A rough measure can be had by having the bar Magnafluxed. If there is
any
intragranular tearing, it should show up as microcracks.

That should read "intergranular tearing." Fatigue is a phenomenon that
occurs BELOW the elastic limit, from repetitive cycling. The tearing I'm
talking about is a result of strain failure BEYOND the elastic limit, and
which could hasten actual fatigue failure.

It could take the form of cracks that start on the surface, and which will
show up clearly with Magnafluxing, but the insideous form is tearing that
occurs just below the surface. Again, it's unlikely that you have a problem
that won't show up with Magnafluxing.

--
Ed Huntress