"Bob Engelhardt" wrote in message ...

Can anybody (Ed ... ?) see anything in the linked photo that might say
something about the break? I left the photo big (2000 x 1200) to keep
details.

It's the shank of an SDS max drill bit. Carbide tipped, so I thought
the shank would be mild. Yet, to me, the break looks like that of hard
steel.

Does the varying color mean anything?

http://home.comcast.net/~bobengelhar...42_resized.jpg

Thanks,
Bob

=================================================

That's interesting. Fracture mechanics is something I haven't dealt with in
20 years, and I never could say anything conclusive about fractures, but it
looks like some kind of shear fracture. In general, the darker area in one
of these fractures indicates fatigue, and the brighter areas indicate
brittle fracture.

It doesn't mean the metal was brittle. If it really was fatigue that started
it, the rest just shows where the remaining metal was overloaded.

I doubt if the shank is anything less than a good tool steel. Mild steel
wouldn't take the pounding. Beyond that, I don't know.

--
Ed Huntress