Mechanical Quality of Sword Blades Past & Present

Before the 15th century, steel was an expensive material and swords were usually made up of several pieces. For example a thin steel core, sandwiched between two iron layers, or steel edges welded onto the sides of an iron piece. Specific measurements of two 17th century rapier blade fragments from Solingen, interestingly still feature the iron-steel-iron sandwich construction^​1​.

During the 15th century, large bloomeries for steel production were functional and provided the material to be used for single-piece, all-steel sword blades. This development went in tandem with armour production (which probably was the driving force behind this development).

Metallurgically analysed blades from the 15th to the 17th century which were made from steel with a carbon content between 0.2 and 0.8% and actually being heat-treated, exhibit edge hardness values in the range from 317VPH (33HRC) to 540VPH (52.1HRC)^​2​.

Modern spring-steel, like 1.5026 (56Si7), contains:

• 0.52-0.6% C
• 1.6-2% Si
• 0.6-0.9% Mn

This steel can have a realistic maximum hardness of 56HRC. With proper annealing to make a sword blade durable for continuous sparring use, it will be around 50-52HRC. This is still far superior to any 15-17th century period blade concerning hardness. Due to the high silicon content of modern spring steel, blades will also perform better in the area of flexibility and toughness. Furthermore, improved temperature control of the whole heat-treatment process increases replicability greatly.

In the past, forging was a nessecity for economic and manufacturing reasons. The bladesmith had to minimize waste and sometimes make a comprimise by combining high quality and inferior materials. Today, forging a swordblade from a steel billet has no practical advantage. Quite to the contrary, as industrially manufactured steel conforms to high standards of homogeneous microstructure and mechanical properties. Trying to keep those intact as much as possible will yield a reliable product.

https://en.wikipedia.org/wiki/Rockwell_scale