[TheForge] Re: Shot-peening article- history and usages

[schade at acegroup.cc]

It was an interesting article and seemed to support the idea that  
packing or "peening" in this case would harden the surface...

http://www.americanheritage.com/articles/magazine/it/2007/3/ 
2007_3_51.shtml

"Shot peening prevents this kind of metal failure because it  
pre-stresses
a part’s surface with permanent compressive stresses. These counteract
the tension stresses that result from loading the part. In addition, the
shot-peening process nullifies stress risers because it applies a layer  
of
compressive stresses to the total part’s surface. This prevents a  
failure
crack from starting."

But if I remember right from the last ten or so times this subject came  
up packing (forging at a dark red of black heat) did not harden the  
surface.

Am I dreaming again?

Bob
___________________





On Jan 10, 2007, at 2:18 PM, Mike wrote:

>
> That a good piece.  Thanks for posting the URL.
>
> They had a shotpeen tower at the Hamilton Standard aircraft plant near
> Hartford, Conn. where I had a summer job circa 1960.  They shotpeened
> the propeller blades, about 5' or 6' long, that I subsequently glued
> deicers and rubberized fabric to.  Made a terrific racket when it was
> running.  I didn't realize at the time that it was Hot Stuff.
>
>
> - Mike
>
> -- 
> Michael Spencer                  Nova Scotia, Canada       .~.
>                                                            /V\
> mspencer at tallships.ca                                     /( )\
> http://home.tallships.ca/mspencer/                        ^^-^^
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