Warring States or late Spring Autumn Bronze Sword
(circa 500 BC)
sword is an interesting example of metallurgy from the Warring States
or possibly the late
Spring and Autumn period. The sword is interesting because it has a
length of 66 cm. and a bi-metallic structure.
A bi-metallic sword is made of different alloys used for different parts cast as a single unit. This sword's blade is made of a yellowish high tin content alloy that provides the hardness required for sharp cutting edges. The handle/hilt is made of a reddish high copper content alloy that provides high strength and flexibility to prevent breakage. It's likely that the high copper alloy continues far into the blade as a high strength spine because there is little sense in attaching a copper handle to a tin/bronze blade, which could then break off easily at the handle.
The manufacture may involve the use of multiple stone moulds, one for the hilt and spine and another for the blade itself. After the high copper content spine is cast in the first mould, the second mould is used to cast the rest of the blade including the edges. Without cross sectioning the sword, it's hard to say exactly what's inside or what the shape of such an internal spine would be
The sword has
another curious feature that may also tie it to the Spring Autumn
period, it is missing the two small rings from its hilt although there
are makings where these rings would have been. One of the most famous
swords, the sword of Goujian, who was the King of Yue at the end of the
Spring Autumn period, is also missing the two rings from its handle and
there are marks where the rings would have been. The sword of Goujian
is 55.6 cm. long.
Left and right images show the sword edge on and blade side on respectively. One aspect of these swords is their thinness, which is required to make the swords light and maintain good balance. The blade is well tapered starting just after the hilt.
Comparison to a standard length 45 cm. Warring States Sword (right)
bellow compare the sword with a classic 45 cm. Warring States sword, edge on and broadside. Both swords are balanced with their pommels resting on a flat piece of glass. As measured, there is only a 0.1 degree difference in angle between the two swords!
shows the joint area between blade
and hilt. The area just below the handguard shows the natural reddish
color of the low tin content bronze used for the hilt and probably the
spine of the
sword. The blade is everywhere a more yellowish bronze. Right image
compares the sword's hilt the hilt of a shorter Warring States sword.
The two bands where the rings would have been on the grip are marked
A 63 cm. sword. http://www.youngmuseum.com/the_richard_nable_collection.htm