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High Tech from the Dark Ages

Hey folks,

I don’t know if anyone would be interested in this, but there’s a
wonderful article in the Winter 2007/Volume 22/No.3 issue of
(American Heritage of) Invention & Techology which is ultimately
about work hardening metal, but which the article calls shot peening.

They begin the story by explaining that the first instance of this
process (though a closely guarded secret at the time) was in the
making of Spanish swords. If you were wealthy you would travel to
Toledo where blacksmiths “had developed blades that were thin and
lightweight and had beautiful proportions. They also could take and
hold a keen edge. But most important, they had a characteristic
unmatched by those from other sword makers: Toledo swords were so
tough that they could be bent almost double, over and over, without
breaking. That made them virtually indestructible in battle.”

The story goes on to explain that it was in the manufacture of
automobiles that the process used to make these swords was
"rediscovered". Specifically in the use of steel shot to descale

If you happen to teach, this would be a wonderful reading
assignment. The closing paragraph says it better than I:

“The serendipitous rediscovery of this millennium-old peening
process has given engineers a way to design parts that will
accept higher loads, or to extend their fatigue life safely. The
explanation of how the process works has led to a better
understanding of how metals fail. Over the decades this knowledge
has been the basis for many other improvements and cost savings
in metal casting, forging, and fabrication technology. That’s why
I think that the basics of shot peening and peen forming should
be required in all college mechanical, aeronautical, and
structural engineering curricula.”

Cool stuff.

This is a quarterly publication, so you should find it available on
newstands for several months. There’s a picture of Don Adams on the
cover using his shoe phone (cover story is about the evolution of the
cell phone). The title of the article is the subject line of this
post. (They are online at - but it
doesn’t appear that the most current issue is uploaded yet).