[TheForge] Dont put your tongue on a frozen anvil round 2

[Grover Richardson]

Yes. Mike.  How's it going, I think I agree with what you said.

Wouldn't constant use of an anvil also cause "micro-peening<G>," but in a
bigger way<G>.  I have a real cheap anvil, and I have dents in the top
surface of it where folks have missed the hot metal, sometimes me I am sad
to say.  Yes, I do understand that a "good" anvil shouldn't have dents in
the top, but it works, I can afford it, and more importantly, it's something
I can lift easily<G>.

I have seen compression spalling (earing over on the working surface due to
excessive wear) in hammers from the civil war.  In fact all the tools that I
saw at a local display were seriously used and abused.  I suspect that
either they were the ones left behind as useless, or someone was desparate
to get the job done<G>.  Then again, we don't know who made them, under what
conditions, or what quality of metal was used.

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Mike Spencer
Sent: Thursday, September 30, 2004 4:27 PM
To: theforge at mailman.qth.net
Cc: theforge at mailman.qth.net
Subject: Re: [TheForge] Dont put your tongue on a frozen anvil round 2



> Not enough information.  Depends upon the anvil, depends upon how hard 
> you hit it, depends upon where you hit it, depends on how cold it is.

Another thought:  Catastrophic crack failures begin at micro-cracks, [1]
whether or not the margin of safety has been reduced greatly by a
combination of hydrogen/sulfur/whatever embrittlement and low temps. So if
you're obliged to use a very cold anvil and are worried, it might be helpful
to have your anvil shotpeened.  This tends to close up micro-cracks and put
a shallow layer of the surface in compression -- sort of pre-stressing in
the direction opposite to the tension that encourages crack propagation.

I don't know just what kind of finish that would leave on the working face
but it would be worth a try.  The only place I've actually seen this in use
was for 6' long aluminum propeller blades but I'm sure it's a widespread
technology.


[1]  I'm not so sure about compression spalling but I think that's more
     complicated and unlikely to happen to anvils used for hand
     hammering.

- Mike

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                                           /V\ 
mspencer at tallships.ca                                     /( )\
http://home.tallships.ca/mspencer/                        ^^-^^

-- 


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