Letter: Letters : Feel the steel

From Ronald Yochum

Pittsburgh, Pennsylvania

Michael Judge discusses the creation of a stronger, stiffer, lighter alloy
made from metals reinforced with microscopic wires of another metal (“It takes
two”, 8 March, p 36).

The process for creating the new alloy may be a breakthrough, but a similar
alloy has been around for hundreds of years. The material is called Damascus steel.
It has been used for generations by knife and sword makers in Japan.

Damascus steel is created by taking two steels, often one softer than the
other, and putting them together like plywood. They are then hammered flat, and
the flattened piece folded over and over and hammered flat again, sometimes
hundreds of times.

Much like the strength of a piece of plywood, Damascus steel is extremely
strong. There were even reports of Japanese swords cutting clear through
Russian soldiers’ gun-barrels during the Russo-Japanese War.

The process that Judge refers to is different from making Damascus steel in
that it disperses metal A throughout metal B, not in alternative layers, but
more like an evenly-distributed foam which is then drawn out, leaving filaments
of one metal inside the other. The molecular structure of the two dissimilar
metals creates a situation where if there was a crack in metal A, the crack
wouldn’t travel through the entire forged piece because it would be stopped by
the dissimilar angle of the molecular structure of metal B, thereby preventing
failure of the entire piece of metal. Much the same is true of Damascus
steel.

This process is intriguing, though, because it brings the fantastic strengths
of Damascus steel without the cost and labour intensity involved in manufacture.
It would be interesting to see whether the new alloy can withstand the corrosive
effects of the electrochemical reaction that occurs between metals when in the
presence of an electrolyte.