Several years ago, I became interested in all things blacksmith.  I paid
for some one on one time with a professional blacksmith who was interested
in armor and sword making, but who made his living doing ornamental iron
work for home and hearth in a small village near me. Anyway, most of what I
had read  about tool steel and tool making  was wrong, (according to him).
Crucible steel has a much longer history than most of us are aware.  There
is also a documentary I found on that tube site about a smithy recreating
one of these legendary swords from scratch - it's worth a watch if you are
interested in this stuff.
For those interested, you can also google this article (I just copied and
pasted the abstract below)
Claudio

Crucible steel in medieval swords
 Alan Williams
 ABSTRACT
 Many Viking-age swords bear an inscription on the blade such as VLFBERHT –
thought to be a maker’s name. It has become evident that some of these were
made of crucible steel. In the past much attention has been focused upon
one particular type of crucible steel,
wootz
, and its characteristic surface pattern, indicative of Oriental sword
blades of high quality, often called ‘Damascus’ steel. Crucible steel,
however, without any such pattern, was also used for making swords. There
is written as well as metallographic evidence of a trade in such steel to
western Europe, apparently by the Vikings, and liquid steel was a material
familiar to medieval chemists.
 Keywords:
 Viking, sword, metallography, Ulfberht, crucible steel,