Download Metallurgical sleuthing sheds light on Viking

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3/20/2009
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Interest
Metallurgical sleuthing sheds light
on Viking trade routes, swordsmithing,
& counterfeiters
I
Although beautiful,
this sword from the
Germanic National
Museum,
Nurnberg,
Germany, is a made
of a low-carbon
steel and is a
contemporary
counterfeit. The
inscription is
+VLFBEHT+.
Credit: Alan
Williams
n the Middle Ages, there were two techniques for making steel for swords. Europeans used the
bloomery process of heating iron ore with charcoal and chemically reducing it into a solid mass of
metal and slag known as a bloom, which consists of iron, slag, and steel. The steel portions had to be
separated from the bulk of the bloom. In
Asia steel was made by the crucible
process which involved heating
pieces of bloomery iron for days
in sealed crucibles with a
carbon-containing material until enough
carbon had been absorbed for steel to be
formed as a liquid and easily separated from the slag.
A collaboration between scientists at the National Physical Laboratory
(NPL) in Teddington, U.K. and curators at the Wallace Collection, London,
U.K. provided evidence revealing that the West has imported steel from the East at
least since the Middle Ages when the Vikings brought high-carbon crucible steel
back from Central Asia.
About 100 Viking-era swords bearing the maker’s inscription, +VLFBEHR+T
(for Ulfbehrt), have been found scattered around northern
This authentic
Europe (see map). Using a highly calibrated scanning electron
Ulfbehrt sword was
microscope, NPL microscopists analyzed the structures and
made of a very
carbon contents, and determined that the swords were made of
high-carbon steel
imperfectly melted steel consisting of a mixture of iron and
(~1.4% C) and
would have been very
carbonaceous materials heated together to give high-carbon
hard. It is from the
steel. NPL’s results match descriptions of ancient sword
Wurttemberg
making in Herat (now in Afghanistan) described by ninth
Landesmuseum,
century Arab philosopher and writer Al-Kindi. This information
Stuttgart, Germany.
links to a known Viking trade route down the Volga and across
The maker’s
the Caspian Sea to Iran; however, until now it was not known
inscription is
that Vikings had brought
+VLFBERH+T.
crucible steel back to
Credit: Alan
Scandinavia and integrated
Williams
ancient Arab steelmaking
methods with their own swordsmithing.
Because the swords forged from crucible steel were the
best available by far, enterprising counterfeiters would have been
very tempted to replicate the swords, perhaps by welding small
pieces of bloomery steel onto a billet of iron and forging it
into a blade before quenching. The sharp edge that could be formed
might deceive less discerning customers, but with a depth of only a
few millimeters, the sword would not have survived many
sharpenings. The inferior versions were sometimes inscribed to help
convince the gullible; however, similar to modern-day counterfeits,
the markings were often misspelled.
Acknowledgments: Dr. Alan Williams, Wallace Collection, London,
U.K. and Mr. Tony Fry, National Physical Laboratory, Teddington, U.K.
Viking trade routes
and locations of
Ulfbehrt sword
discoveries. Credit:
Alan Williams
4
For a scholarly article on the history and metallurgy of medieval
Viking swords, see Williams, Alan, “Crucible steel in medieval swords” in Metals and Mines, edited by
S. LaNiece, D. Hook, and P. Craddock (Archetype Press with the British Museum, London, 2007),
233-241. ISBN 978-1-904982-19-7.
For more information visit www.npl.co.uk or www.wallacecollection.org.
ADVANCED MATERIALS & PROCESSES/APRIL 2009