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

[Rich Maynard]

Theres a world of difference between hardening the surface (which =
'packing'
is claimed to do) and increasing the resistance of metal parts to =
cracking
(which this article talks about)

Rich M.

> -----Original Message-----
> From: theforge-bounces at mailman.qth.net=20
> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of=20
> schade at acegroup.cc
> Sent: 10 January 2007 20:57
> To: Sponsored by ABANA; mspencer at tallships.ca
> Subject: Re: [TheForge] Re: Shot-peening article- history and usages
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> It was an interesting article and seemed to support the idea that =20
> packing or "peening" in this case would harden the surface...
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> http://www.americanheritage.com/articles/magazine/it/2007/3/=20
> 2007_3_51.shtml
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> "Shot peening prevents this kind of metal failure because it =20
> pre-stresses
> a part=92s surface with permanent compressive stresses. These=20
> counteract the tension stresses that result from loading the=20
> part. In addition, the shot-peening process nullifies stress=20
> risers because it applies a layer =20
> of
> compressive stresses to the total part=92s surface. This prevents a =20
> failure
> crack from starting."
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> But if I remember right from the last ten or so times this=20
> subject came =20
> up packing (forging at a dark red of black heat) did not harden the =20
> surface.
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> Am I dreaming again?
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> Bob
> ___________________
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> On Jan 10, 2007, at 2:18 PM, Mike wrote:
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> >
> > That a good piece.  Thanks for posting the URL.
> >
> > They had a shotpeen tower at the Hamilton Standard aircraft=20
> plant near=20
> > Hartford, Conn. where I had a summer job circa 1960.  They=20
> shotpeened=20
> > the propeller blades, about 5' or 6' long, that I=20
> subsequently glued=20
> > deicers and rubberized fabric to.  Made a terrific racket=20
> when it was=20
> > running.  I didn't realize at the time that it was Hot Stuff.
> >
> >
> > - Mike
> >
> > --=20
> > Michael Spencer                  Nova Scotia, Canada       .~.
> >                                                            /V\
> > mspencer at tallships.ca                                     /( )\
> > http://home.tallships.ca/mspencer/                        ^^-^^
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