Why Mild Steel is Acceptable For Re-Enactment Weapons

I make most of my weapons about of medium to high carbon steel to ensure that they perform well for the modern consumer. However, if you're a re-enactor and looking for weapons that perform like historical weapons, mild steel might not be the worst choice.

A 13th century sword made of EN9 steel with similar properties to some of the very high quality medieval steels

Throughout history, steel quality has varied. People were able to make good-quality steels that were capable of being hardened and tempered to produce a tough blade with good edge retention.

The biggest problem is that mild steel can bend under extreme impacts and dull quite fast. This is seen as inferior by modern consumers, however many historical blades displayed these qualities too.

The majority of medieval blades were made from bloomery steel and less commonly, crucible steel. Both of these have their drawbacks compared to modern steels. Bloomery steel was often quite soft and malleable.

While some medieval smiths were able to select harder pieces for the edge, they were still left with a soft spine on the blade which could bend. There are many sources saying that blades would have to be bent back after combat, which indicates that this steel wasn't through-hardened as we expect with modern mono steels. This will be due to the core not having enough carbon.

The bending wasn't historically seen as a lack of quality in the blade as even traditional bladesmiths in Japan, who have a rich history of swordmaking and a living tradition, design their swords to bend rather than break. They do this by including a soft iron core and a harder steel on the edge that could be quenched.

Crucible steel is often romanticised as being a medieval super steel. It usually has a high carbon content and higher purity than bloomery steel due to the lack of oxidation in the crucible. However, the method of mixing charcoal with the iron ore produces steel with an extremely high carbon content - much higher than what we would see in usable steels today. This means that the steel was often harder in its anneled state but any heat treatment process would make the blade extremely brittle that not even tempering could save it. Oftentimes, crucible steel blades simply weren't heat-treated.

A Norman sword made from 1095 high carbon steel which has a similar carbon content to some crucible steels

As we can clearly see, medieval swords would often bend in combat which we try to avoid by buying high-quality steels today. Mild steel would be a better analogue for what would be commonly found in the era due to the fact that it can be bent by impact and returned to its shape by simply bending it over your knee.

The construction of mediaval swords was obviously more nuanced than forging a sword form a mono steel. However, the mechanical properties of mild steel in many of the softer swords made throughout history is undoubtedley quite similar.

Not all mediaval weapons were made form low quality steels but many munitions-grade items were. In re-enactment battles most people wil be impersonating normal soldiers who, in the period, would not have been able to afford the best-quality wepons. Therefore I believe that using mild steel weapons as sharps for cutting tests and blunts for reenactment would give us a more accurate picture of how medieval weapons performed.

Medieval blades were often heat treated in some way but with different results compared to what we expect on modern replicas. Often times, bloomery steel would be shallow hardening partially due to the carbon added to the steel from forging in a charcoal forge, meaning they would gain a certain amount of spring-like qualities but no way near what we can achive today. They could still take a set if the blade was bent too far. Through chemical testing it is also shown that medieval sword blades could vary in hardness from 23 to 58 Rockwell within the same blade.

A roughly-made mild steel speerhead

Mild steel is often considered un-hardenable. However, when quenched, it can be shallow-hardening as small amounts of martensite can form on the outer layer, giving it a very slight boost in edge retention and mild spring like qualitites. This essentially creates a blade that performs in a similar way to what many medieval blades would.

In conclusion while medieval steels varied significantly in quality and properties, re-enactors who care about providing an accurate view of medieval warfare should be more open to using mild steel weapons while demonstrate historical warfare, as their properties are very similar to many weapons you would have found on the mediecal battlefield. While high quality weapons are common in re-enactment I believe it's also important to show off the lower quality items that would have been common throughout history to create a more accurate picture of the past.