Basic Metallurgy of Swords

in Blade

In your martial arts journey you are likely to own a variety of swords, and will almost absolutely face a multitude of choices. How do you choose? How do you pick the right one? Well, the first question is the reason for this article. The second question, however, has an easy answer -- there is no such thing as "the right one". You should be thinking instead of "the right tool for the job". Different sword strengths and geometries will be more appropriate for different actions. You need to let the functionality dictate which sword to use for that particular job. So, on to answer the first question, this will also help guide you in the second.

Before you buy, you should take some time to study these issues. If necessary, take this check list along with you.

There are three primary issues you should always consider when looking to own a sword.

1) The quality of the Steel.
2) The quality of the Heating and Tempering.
3) The geometry of the blade.

1) The quality of the steel. There is a dizzying array of steels available on the market today, but you can simplify everything with a couple simple categories. A simple format is to divide the types into Stainless Steels and High Carbon Steels.

Stainless Steels are those blades which have had chromium added to the metal in order to retard the propensity to rust. This is a very good thing when you are dealing with general kitchen and field knives. However, it is a horrible thing when you are dealing with swords. In general, cheap swords are made with Stainless Steel. It is used because it is easy to manufacture. The problem is that the addition of chromium also creates a physical limitation in the tempering of the blade. In essence, it prevents the blade from being tempered to a point where it is flexible and resists breaking. In simple words, it keeps the blade too hard. Too hard is a problem because the blade is then prone to breaking. This will probably be clearer after I describe Heating & Tempering and geometry.

High Carbon steels are preferable for swords because they maintain their flexibility and "toughness". Toughness is very different from "hardness". In fact, they are diametrically opposed to each other. Let me illustrate. "Tough" is like a lead pipe. You can beat it against concrete and it will most likely bend, rather than break. "Hard" is like glass. Glass is very hard, and will take a very keen edge, but is brittle and prone to breaking with moderate contact. High Carbon steels can be tempered to proper toughness for the required job. Stainless Steels have a limitation and cannot be made "tough". Therefore High Carbon steels are preferred for sword blades.

Another generalized grouping you must be aware of for Chinese Weaponry, is the difference between "Asian Spring Steel" and "Western Spring Steel". You will hardly ever hear them referred to in these terms, but I like using them because it clarifies a lot of misconceptions.

Western Spring Steel is usually a very specific type of steel. Normally 5160 (low chromium, medium carbon steel) that is extremely tough and very well suited for swords, knives, and axes. Its cost is low and readily available to sword makers around the world because this is the steel that is used in car and truck springs. Hence, the name.

Asian Spring Steel, on the other hand, is just about any hodge-podge of gathered and melted together steel that will bend to some extent and hopefully "spring' back to close to its original shape. It is normally full of impurities, can have hidden fissures that will allow the blade to break unpredictably (and very dangerously), is very cheap, and should normally be avoided. Unfortunately, this is what you will find most Asian weapons are made of and they have flooded the martial arts community. They are cheap and dangerous. Besides, if you really want to learn your swordsmanship, these will actually work against you because they lack realistic weight, balance, and rigidity. They can almost, normally, be much too floppy to be realistic.

2) Heating & Tempering. Without getting into the technical details, all "steels" must go through a forging process where the metal is heating and then cooled to the desired temper. That is, heating the steel hardens it, and then a tempering process softens (correct term is "tempers") the steel to the desired toughness. It is a curious physical property of steel that it cannot be heated to a certain point and that is it. The steel must be taken to the hardness level and then drawn back to the desired toughness level. Hopefully you noticed that "tempered" and "drawn" steel are many times used interchangeably.

This is somewhat redundant, but I will say it again. If the blade is left too "hard" it can be broken with a moderate, or even a soft hit to the right spot. This is why stainless steel is a dangerous problem. Stainless Steel cannot be tempered for toughness.

Here is a huge point to be remembered -- It does no good whatsoever to start with very high quality steel and then ruin it through improper heating and tempering. You will have a much better blade if you started with low quality steel, but subjected it to a superior and carefully calibrated heating and tempering process.

You want a blade that is hard enough to take a keen edge (nice, sharp, cutting edge), yet at the same time tough enough to handle the rigors of battle. There is an artful balance between the two.

3) Geometry of the blade. Unfortunately this is often one of the most overlooked aspects when selecting a sword, or knife, for that matter. Put simply, a short, thick object is harder to break than a long, thin object. Take this thought over to the shape of a knife or sword blade. A short blade that is ¼" in thickness will be difficult to break. You may even be tempted to improperly use it as a small pry bar. A long blade that is the same ¼" in thickness will be easier to bend, or perhaps even break (depending on the temper). The shape of the blade is critical to how much work the blade will tolerate over the entire surface and at the edge.

Not only is the length and curvature (or lack thereof) extremely important to the functionality of the blade, but so is the width and thickness. A long blade will give you reach, but at the expense of increasing the propensity to bend or break. A curved blade shortens the distance, but improves portability and drawing effectiveness (pulling the blade out of the sheath quickly). A wide blade increases the surface tension (resistance to damage) but also increases weight and decreases the ability to wield the sword (control and swiftness). A thick blade also increases the weight (allowing for greater follow-through and making it harder to block the swing), but will also decrease the cutting performance if it is too thick. Conversely, a thin blade decreases the weight, making the sword swifter, but increases the propensity towards edge damage.

I know this is a lot to think about. I want you to get a basic understanding for some of the aspects that go into a proper sword that will do the job effectively. I want you to have the background knowledge for the basic thing that should always be at the forefront of your decision making process -

The right tool for the job.

You do not want to use a long, thin blade to parry a heavy, thick, medieval type sword. You do not want to use a heavy chopping blade when doing finesse work and selective cutting. This is why so many cultures have developed so many different types of blades for so many different uses.

The person you are buying your sword from should be able to answer your questions and help you through this process. Seek and get help from professionals that know what they are talking about and can help you.

If you have any doubts on any of this, you are more than welcome to call us at 1-800-508-0825 and we will do our best to answer your questions. You can also visit us at http://www.ValleyMartialArts.com for more information. A good sword does not have to be expensive, but a cheaply made sword can be very dangerous.

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Rafael Kosche has 1 articles online

Rafael Kosche
800-508-0825
http://www.ValleyMartialArts.com

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Basic Metallurgy of Swords

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This article was published on 2010/04/02